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CONTENTS
Section Page

SCOPE ............................................................................................................................................................3

REFERENCES.................................................................................................................................................3
DESIGN PRACTICES .............................................................................................................................3
COMPANY TECHNICAL REPORTS .......................................................................................................3
OTHER REFERENCES...........................................................................................................................3

BACKGROUND ...............................................................................................................................................3

SCREENING PROCESS FOR UTILIZING FINNED TUBE TECHNOLOGY ...................................................3

HEAT TRANSFER COEFFICIENTS........................................................................................................4
FOULING.................................................................................................................................................4
CORROSION ..........................................................................................................................................4

GRASSROOT DESIGN VERSUS EXISTING EXCHANGER MODIFICATION ...............................................4

GRASSROOT DESIGN ...........................................................................................................................4
Economics ............................................................................................................................................4
EXISTING EXCHANGER MODIFICATION .............................................................................................4
Tubeside Pressure Drop.......................................................................................................................5
Shellside Pressure Drop.......................................................................................................................5
Tube Vibration ......................................................................................................................................5
Economic Incentives.............................................................................................................................5

SPECIFYING FINNED TUBES ........................................................................................................................5

FIN SPACING AND HEIGHT...................................................................................................................6
FIN SHAPE..............................................................................................................................................6
FIN THICKNESS .....................................................................................................................................6
MINIMUM TUBE WALL THICKNESS......................................................................................................6
LANDS ....................................................................................................................................................6
INTERNAL TUBE ENHANCEMENTS .....................................................................................................6

THERMAL AND HYDRAULIC ANALYSIS ......................................................................................................7

THEORY..................................................................................................................................................7

CALCULATION PROCEDURE FOR EXTERNAL LOW FIN TUBES..............................................................7

COMPUTER PROGRAMS ......................................................................................................................7
HAND CALCULATION FORMS...............................................................................................................7
SECTION IX-D MODIFICATIONS ...........................................................................................................7
Estimation Method Calculation Form, Shell and Tube Heat Exchangers (No Change of Phase) ........7
SECTION IX-E MODIFICATIONS ...........................................................................................................9
Heat Transfer Calculation Form for Kettle and Internal Reboilers ........................................................9

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CONTENTS
Section Page
Heat Transfer Calculation Form For Vertical Tubeside Thermosiphon Reboilers ..............................10
DESIGN PRACTICE IX-F MODIFICATIONS.........................................................................................10
I. Zone Duties and Temperatures......................................................................................................10
II. Shellside Condensation.................................................................................................................10
III. Tubeside Condensation................................................................................................................11

NOMENCLATURE.........................................................................................................................................12

TABLES
Table 1 Physical Data For Typical Low-Finned Tubes (Customary Units)................................15
Table 1M Physical Data For Typical Low-Finned Tubes (Metric Units) .......................................17
Table 2 Fins Dimensions For Various Tube Materials (Customary) .........................................19
Table 2M Fins Dimensions For Various Tube Materials (Metric) .................................................19

FIGURES
Figure 1 Sketch Of A Low Finned Tube Showing Typical Cross-Section And Geometry...............21
Figure 2 Heat Transfer Coefficient Correction For Low-Finned Tubes ............................................20
Figure 3 Weighted Fin Efficiencies For Low-Finned Tubes (Customary Units)...............................21
Figure 3M Weighted Fin Efficiencies For Low-Finned Tubes (Metric Units) ......................................22
Figure 4 Pressure Drop Correction For Low-Finned Tubes.............................................................23
Figure 5 Shell Side Maldistribution Correction ................................................................................24

APPENDICES
Appendix A-1 Estimation Method Calculation Form (Customary Units) Shell And Tube
Heat Exchangers (No Change Of Phase) ..................................................................25
Appendix A-1M Estimation Method Calculation Form (Metric Units) Shell And Tube Heat
Exchangers (No Change Of Phase)...........................................................................33
Appendix A-2 Example Problem (Customary Units) Shell And Tube Heat Exchangers
(No Change Of Phase)...............................................................................................41
Appendix A-2M Example Problem (Metric Units) Shell And Tube Heat Exchangers
(No Change Of Phase)...............................................................................................49

Revision Memo
12/99 Added new sections on Finned Tube Screening Process, Grassroot vs.
Debottlenecking Applications, and Specifying Finned Tubes.
Revised required modifications to calculations in Sections IX-D, IX-E, and IX-F.
Updated NOMENCLATURE.

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SCOPE
This practice deals with the application of external low finned tube technology. It addresses specific issues, including; the
screening process for choosing finned tubes, special considerations for both debottlenecking and grassroot applications,
specifying finned tubes, and accounting for the thermal and hydraulic effects of finned tubes on heat exchanger operation.
Low finned tubes are especially economical when the shellside resistance to heat transfer is greater than three times the inside
resistance. This is typically true for coolers, condensers, and reboilers, and is often the case with oil-to-oil exchangers.
Low finned tubes can be used to increase heat transfer in an existing shell, simply by retubing the bundle with low fins. When
this route will give the desired heat transfer, it is always cheaper than providing an additional shell.

REFERENCES
DESIGN PRACTICES
Section IX-A Heat Exchanger Equipment - Exchanger Types and Applications
Section IX-C Heat Exchanger Equipment - Design Considerations for Shell and Tube Exchangers
Section IX-D Heat Exchanger Equipment - Calculation Procedure, No Change of Phase
Section IX-E Heat Exchanger Equipment - Calculation Procedure, Vaporization
Section IX-F Heat Exchanger Equipment - Calculation Procedure, Condensation

COMPANY TECHNICAL REPORTS

1. Field Applications of Double Enhanced Tubes in Shell-and-Tube and Air-Cooled Heat Exchangers, ER&E Report No.
EE.108E.94, December 1994.
2. Heat Transfer Performance Enhancement Using HiTRAN Inserts, ER&E Report No. 94.ESC4.010, 1994.
3. Enhancing Heat Exchanger Performance with Turbulence Promoters, ER&E Report No. EE.14E.88, January, 1988.
4. Enhanced Heat Transfer Technologies for Improving Heat Exchanger Performance, ER&E Report No. EE.49E.88,
November, 1988.
5. Survey of Tube-Side Heat Transfer Enhancement Techniques, ER&E Report No. EE.20E.83, March, 1983.

OTHER REFERENCES
1. Heat Transfer Research Inc. (HTRI), Design Manuals
2. Heat Transfer Research Inc. (HTRI), Computer Support Volume
3. Third Exxon Heat Exchanger Forum (October 29 - 31, 1957); Topic 3D-2
4. W. O. Weber Article, Humble Oil & Ref. - Baytown, TX (Chem. Engr. Vol 67, No. 6, Page 149 (1960))

BACKGROUND
Externally finned tubes, also commonly known as Integral-Fin Tubes (IFT) or Low Fin Tubes, have extended external heat
transfer surface area that is approximately 2.5 times greater than that of the same diameter plain surface tubes. The extended
surface area is achieved by a cold-rolling process that produces short fins ranging in density from 11 to 40 fins/in. (430 to 1575
fins/meter) and in height from 0.030 to 0.060 in. (0.75 to 1.5 mm). Figure 1 is a sketch of a typical low-finned tube.
The low-finned technology, developed in the late 1940's, has been successfully applied in both clean and fouling services. In
the 1960's and 1970's, finned tubes started becoming available in a wide range of corrosion resistant materials. Whereas early
finned tube production was driven by the manufacturing techniques available at that time, there have been significant
manufacturing and performance improvement developments associated with fin shape and fin density (i.e., fin spacing). Unlike
other heat transfer enhancement technologies that have specialized application in vaporizing or single-phase streams, finned
tubes have been used very effectively in single-phase, condensing, and vaporizing services.

SCREENING PROCESS FOR UTILIZING FINNED TUBE TECHNOLOGY

This section covers general items that need to be addressed when considering an application for external low finned tube
technology. It is important to consider these items for finned tube applications in both new designs and existing exchanger
modifications. The next section, GRASSROOTS DESIGN VERSUS EXISTING EXCHANGER MODIFICATION, addresses
issues specific to the two types of applications.

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SCREENING PROCESS FOR UTILIZING FINNED TUBE TECHNOLOGY (Cont)

HEAT TRANSFER COEFFICIENTS

In order for the utilization of externally finned tubes to be beneficial, the shellside heat transfer coefficient must be lower than the
tubeside heat transfer coefficient. The incentive for using finned tube technology increases as the difference between shellside
and tubeside heat transfer coefficients increases and is especially attractive when the outside resistance is three or more times
the inside resistance. When the shellside coefficient is not greater than the tubeside coefficient, it is unlikely that there will be
significant economic incentive to using finned tubes over standard plain (i.e., bare) tubes.

FOULING
There is not a single general answer to the question of whether externally finned tubes can be used when the shellside stream
fouls. Research and experiences, some within Exxon from more than 20 years ago (Other References 3 and 4) has shown that
there are types of fouling for which finned tubes foul less and are easier to clean than bare tubes. In other cases, where a
foulant formed between the fins and expanded during formation or correct corrosion resistant material was not available, tube
failure has occurred. With the currently available range of materials and tube geometries, many fouling applications can be
considered for a finned tube application.

CORROSION
The corrosion rate of the tube material must be considered when applying externally finned tubes. As shown in Table 2, finned
tubes are available in a wide range of materials. The thickness of the fin depends on several factors, but is mainly controlled by
the tube material and the fin spacing (i.e., number of fins per in. or meter). In general, the corrosion rates of higher alloy tube
materials, such as titanium, are low and therefore standard fin thickness is adequate. However, when a corrosive service uses a
low alloy tube, such as carbon steel, the designer should consider the effect of corrosion rate on fin thickness. A corrosion rate
that is high relative to fin thickness may result in the fins corroding away in an unacceptably short period of time. When this
situation is encountered, the designer should consider using tubes that have thicker fins or consider upgrading the metallurgy.
See the "Specifying Finned Tubes" section below for more information on choosing the right type of finned tube.

GRASSROOT DESIGN VERSUS EXISTING EXCHANGER MODIFICATION

Finned tubes can be installed during the design of a new heat exchanger or as a modification to an existing heat exchanger.
Implementing finned tubes during a grassroot design can result in an exchanger that is smaller in size, while implementing
finned tubes to an existing exchanger can increase the exchanger's heat transfer capacity.

GRASSROOT DESIGN
Using finned tubes can reduce an exchanger's size by either a reduction in tube count, shorter tube length, or a decrease in the
number of required shells. In general, the size of the reduction increases as the difference between the shellside and tubeside
coefficient increases, where the tubeside coefficient is larger than the shellside coefficient.

Economics
Although a finned tube exchanger will be smaller than the required plain tube exchanger(s), the finning process adds additional
cost to each tube. The effect this has on the tube price per unit length depends on the tube material. On a percentage basis,
the increase in price per foot is less for higher alloy tubes compared to low alloy tubes. For example, the per unit length cost for
carbon steel tubes may increase 75% for a finned tube, while the per unit length cost for titanium may increase 20%.
In addition, since exchangers that use externally finned tubes weight less and are more compact, the overall installation costs
are less than that required for a plain tube exchanger.

EXISTING EXCHANGER MODIFICATION

Fin tube technology can be used as a debottlenecking or revamping tool for an existing plain tube heat exchanger. The fact that
the diameter over the finned (DOF) portion of the tube is equal to or less than the diameter of the unfinned (Do) portion (see
Figure 1), permits this type of tube to be physically installed in the same diameter holes as would be required for bare tubes. By
adding finned tubes, the heat transfer area is increased without any additional modifications to the exchanger. For example, the
tube-for-tube replacement of bare tubes in a water-cooled condenser provides 2.5 or more times the condensing surface area
compared to plain tubes, while retaining the same shell, piping, insulation, and other total erected costs that would be
associated with the purchase of a new, larger heat exchanger.

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GRASSROOT DESIGN VERSUS EXISTING EXCHANGER MODIFICATION (Cont)

In addition to the requirements stated in the above section, SCREENING PROCESS FOR UTILIZING FINNED TUBE
TECHNOLOGY, listed below are several items to consider before applying externally finned tubes to an existing plain tube heat
exchanger.

Tubeside Pressure Drop

Although the tube count and tube OD will remain identical to the original bare tube arrangement, changing to externally finned
tubes results in an increase in tubeside pressure drop. This is caused by the reduction in tube inside diameter necessary to
produce the required fin height and tube wall thickness under the fin. For example, if a tube 1 in. (25.4 mm) OD tube is specified
to have a fin height (see section SPECIFYING FINNED TUBES) of 0.049 in. (1.25 mm) with an average wall thickness of 0.065
in. (1.65 mm), the resulting inside diameter in the finned section will be 0.772 in. (18.34 mm), which is 11% less than the tube
inside diameter of a 1 in. (25.4 mm) OD bare tube with a tube wall thickness of 0.065 in. (1.65 mm). With all other parameters
constant, in general, tubeside pressure drop is inversely proportional to tube inside diameter to the fifth power. Therefore, a
5
reduction in tube inside diameter of 11% may increase the tubeside pressure drop by approximately 80% (1/.89 = 1.79) In
finned tube applications where metallurgy has been upgraded, the new corrosion rate may allow a reduction in the required tube
wall thickness under the fin. This reduction could help offset the tube inside diameter penalty on pressure drop. However,
before any wall thickness reduction is made, a flow induced vibration analysis for the new operating conditions must be
performed. See Section IX-C for more information on flow induced vibration.

Shellside Pressure Drop

The addition of externally finned tubes to an existing exchanger generally results in an decrease in shellside pressure drop. The
decrease in pressure drop is a result of the effectively larger gap between adjacent tubes caused by the fin spacing. The
magnitude of the decrease in pressure drop will vary for each application. Depending on other factors, such as vibration and
tube unsupported length, it may be possible to offset the change in pressure drop by altering the baffle arrangement. See
Section IX-C, for additional information on shellside pressure drop in shell and tube heat exchangers.

Tube Vibration
A vibration analysis should be performed when replacing existing plain tubes with externally finned tubes. A vibration analysis is
required because a finned tube has a different natural frequency and critical velocity than a plain tube with the same tube wall
thickness and diameter. In addition, finned tubes may also affect the shellside velocity and vortex shedding frequency (see
Section IX-C, Flow Induced Vibration). When adding finned tubes and upgrading metallurgy, the lower corrosion rate of the
upgraded metallurgy allows for the use of thinner walled tubes. The thinner tube wall may increase the potential for tube
vibration.

Economic Incentives
In debottlenecking and revamping applications, the incentive for replacing plain tubes with finned tubes is to increase a unit's
capacity either by allowing for an increase in product throughput or to transfer more heat for the same operating condition.
Since finned tubes require no additional modifications, they can provide an effective alternative to adding additional shells or
replacing an existing exchanger.

SPECIFYING FINNED TUBES

The geometry (e.g., FPI, fin height, fin thickness) of a finned tube depends on many factors but is strongly influenced by both
the fin tube manufacturer and the tube material. The example fin tube dimensions listed in Table 1 can be used for scoping
purposes. Whenever considering the application of finned tube technology, the designer should contact the fin tube
manufacturer and obtain the correct tube dimensions. The designer must supply the vendor with the following information: tube
material, tube OD, allowable minimum wall thickness under the fins. The vendor can then supply the geometrical parameters
including, fin spacing, fin height, minimum wall thickess, and average fin thickness, for the various option(s) available.

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SPECIFYING FINNED TUBES (Cont)

FIN SPACING AND HEIGHT

The choices that a designer has for fin spacing depends on the tube material and the manufacturer from whom the tubes are
being purchased. For example, carbon steel finned tubes are commonly available with fin spacing per in. (FPI) of 11,19, 26 and
36. However, it is unlikely that one individual manufacturer will make all four variations. In general, manufacturers try to obtain
an outside surface area that is at least 2.5 times the surface area of a plain tube with the same OD. Therefore, if a manufacturer
makes a tube that has a higher fin spacing (e.g., 19 FPI or 748 fins/meter) the tube will usually have fins that have a larger fin
height than a tube that has lower fin spacing. Table 2 shows commonly available number of fins per in. for a given tube
material. As shown in the table, titanium tubes are only available in FPIs above 30 (1180 fins/meter). The high fin count is
required to compensate for the low fin height, which is a result of a manufacturing limitation caused by the hardness of titanium.
Depending on the manufacturer, titanium finned tubes may have a FPI between 30 and 43 (1180 and 1693 fins/meter).
Finned tubes, like closely spaced parallel plates, can retain liquid between the fins by capillary (surface tension) forces. The
retained liquid covers the heat transfer surface and makes it less effective. This condition usually occurs during condensation.
The HTRI computer models account for this reduction in heat transfer. The penalty is proportional to both the fin density
(fins/length) and the surface-tension-to-density-ratio of the process fluid. For example, water produces a high flooding penalty.
Therefore streams condensing steam would generally only benefit from finned tubes with low fin density (e.g., 11 fins/in. or 433
fins/meter).
In single phase application where the shellside Reynolds Number is below 500, consider using tubes with fin spacing no greater
than 11 fins per inch (433 fins per meter). Closely spaced fins will be less effective because of the low shellside mixing.

FIN SHAPE
When integral-fin tubes (IFT) were first manufactured, the fin shape was determined by the manufacturing technology available.
Since then, research has shown that the shape of the fin can significantly enhance heat transfer performance in addition to
increasing the surface area. In single phase applications with low conductivity metal, shorter, more closely-spaced fins provide
area enhancement with higher fin efficiency than longer fins. For condensing service, the actual shape of the fin, in addition to
length, affects the heat transfer coefficient and removal of condensate. Some manufacturers have developed special fin shapes
for condensation. In vaporizing service, especially reboilers, finned tubes with special shaped fins (e.g., Wieland GEWA-T see
Figure 6B of Section IX-A) provide significant enhancement in heat transfer over traditional finned tubes.

FIN THICKNESS
Fin thickness is important with low alloy materials that have high corrosion rates. Fin thickness varies depending on the
manufacturer, tube material, and fin spacing. Table 2 lists the range of fin thickness for commonly available finned tubes. The
fin thickness should be considered relative to expected tube life and corrosion rate.

MINIMUM TUBE WALL THICKNESS

As shown in Figure A, the minimum wall thickness, for finned tubes occurs under the fin. The difference between the minimum
wall thickness and the average wall thickness depends on the tolerances of the manufacturing process.

LANDS
Lands are unfinned areas on the tube. These areas are at each end where the tube is within the tubesheet and sometimes at
intermediate points to provide support where the tube passes through the support baffles. Because the finned outside diameter
on some manufacturers tubes is smaller than the unfinned ends, a land area can provide tighter fit where the tube passes
through the baffle. This can be helpful in a case where tube vibration is a problem. However, manufacturing technology is now
available to produce finned tubes with the finned outside diameter equal to the unfinned ends. For such tubes, lands at the
baffles provide negligible additional support. Finned tube applications in Exxon generally use tubes without land areas at the
baffles.

INTERNAL TUBE ENHANCEMENTS

External finned tubes can also be combined with one of the tube side enhancements described in Section IX-A. Such
combined technologies (e.g., IFT with integral tube side ribs/fins) are commercially available and are in successful applications
at Exxon affiliates. Combinations of finned tubes with insertable type turbulence promoters or continuous, on-line mechanical
cleaning devices (see Section IX-A for descriptions) can also be very cost effective and are in Exxon affiliate applications. For
additional information see the ER&E Technical Reports in the reference section.

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THERMAL AND HYDRAULIC ANALYSIS

THEORY
In general the shell side heat transfer coefficient for a bare tube hbare, is related to the total duty Q, bare tube outside surface
area Abare, and the difference in temperatures between the bare outside tube wall and the shell side fluid bulk temperature ∆T,
as expressed in the following equation:
Q = (hbare) (Abare) (∆T)

For low-finned tubes the following differences between bare tubes and low-finned tubes must be accommodated:
• The outside surface area must account for the extra surface of the fins.
• The tubewall temperature must account for the variation along the height of the fin (i.e., fin efficiency).
The following equation shows the required modifications for low-finned tube application:
Q = (hbare Abare + hfin ηf Afin) (∆T)

where:
Abare = Total outside bare tube surface area, ft2 (m2)
Afin = Total outside fin surface area , ft2 (m2)
ηf = Theoretical fin efficiency, Dimensionless
hbare = Bare tube heat transfer coefficient , Btu/hr ft2F (W/m2 K)
hfin = Fin tube heat transfer coefficient , Btu/hr ft2F (W/m2 K)
Q = Heat duty, Btu/hr (W)
For the purpose of manual calculations it will be assumed that hfin = hbare so the equation reduces to:
Q = hbare (Abare + ηf Afin) (∆T)

CALCULATION PROCEDURE FOR EXTERNAL LOW FIN TUBES

COMPUTER PROGRAMS
HTRI's computer programs are recommended for exchanger thermal and hydraulic modeling. The programs have the capability
to accurately model externally finned tube exchangers. The HTRI programs also perform a simplified vibration analysis.

HAND CALCULATION FORMS

This section specifies the modifications required to the hand-calculations in Sections IX-D, IX-F, and IX-E to account for the
effect that externally finned tubes have on heat transfer and pressure drop. This method is applicable only to low fins and
cannot be used for other types of extended surface exchangers. Results from these hand calculations should be verified by an
HTRI computer program.
The dimensions necessary to calculate pressure drop and heat transfer across banks of low-finned tubes are illustrated in
Figure 1.

SECTION IX-D MODIFICATIONS

Required modifications to calculation form in Section IX-D Calculation Procedure, No Change of Phase are identified below.
See Section IX-D for any undefined nomenclature. In addition, Tables A-1 and A-1M, of Section IX-G, provide a detailed
calculation form which includes the modifications necessary to account for finned tubes when applied in single phase
applications.

Estimation Method Calculation Form, Shell and Tube Heat Exchangers (No Change of Phase)

1. Values for single tube outside area per unit length, AT, (equal to AO′) should be obtained from Table 1 or 1M of this
section.
2. Values for tube wall thickness in finned section, l , should be defined as:
dr − di′
l = Eq. (1)
2

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CALCULATION PROCEDURE FOR EXTERNAL LOW FIN TUBES (Cont)

3. Equations using tube inside diameter, di, (e.g. velocity, mass velocity, and Reynolds Number) should be revised to use
inside diameter of the low-finned tube, d′i , where d′i is shown in Figure 1.

4. Equations using inside fouling resistance based on outside surface area, rio, should be revised to use, rio′ , to account for
finned surface area, where:

 AO′ 
rio′ = ri   (AO′ / Al′ obtained from Table 1 or 1M) Eq. (2)
 AI′ 

5. Equations using inside heat transfer coefficient based on outside surface area, hio, should be revised to use, h′io, to account
for the finned surface area, where:

 Al′ 
h′io = hio   Eq. (3)
 AO′ 

6. Equations using wall resistance, rw, should be revised to use, rw′ , where:

l [dr + 2 N′f (12 l′ ) (dr + 12 l′ )]

rw′ = (Customary) Eq. (4)
(12) k w (d r − l )

l [dr + 2 N′f (1000 l′ ) (dr + 1000 l′ )]

rw′ = (Metric) Eq. (4)M
1000 k w (d r − l)

7. Number of finned tubes, NTT′, should be calculated as:

As
NTT′ = (AO′ is obtained from Table 1) (Customary) Eq.(5)
(L − 0.5) AO′

As
NTT′ = (AO′ is obtained from Table 1M) (Metric) Eq. (5)M
(L − 0.15) AO′

8. In the "Iteration, Shellside" subsection, equations using outside diameter, do, should be revised to use, DEQ, to account for
the low-finned tube equivalent diameter, DEQ, instead of the bare tube outside diameter, where:

DEQ = dr + (DOF – dr) N′f t ′f Eq. (6)

9. The calculation of Total Flow Reynolds Number, Rext, should be revised to account for the low-finned tube equivalent
diameter as follows:

(DEQ) (G ′xt )
Re ′xt = (Customary) Eq. (7)
29 µ b

(DEQ) (G′xt )
Re ′xt = (10 −3 ) (Metric) Eq. (7)M
µb

10. Equations using the shellside heat transfer coefficient, hs, should be revised to use, h′o , to account for the finned surface
area, where:
−2 / 3 0.14
1  c p µb   µb 
h′o = = 0.415 c p (G′xt ) (FFB h ) ( ji )     β α fh (Customary) Eq. (8)
 k 
R ′o    µw 

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CALCULATION PROCEDURE FOR EXTERNAL LOW FIN TUBES (Cont)

−2 / 3 0.14
1  cp µb   µb 
h′o = = 7.5 c p (G′xt ) (FFBh ) ( ji )     β α fh (Metric) Eq. (8)M
 0.414 k 
R ′o    µw 

where: αfh is the finned tube heat transfer coefficient correction factor from Figure 2 in Section IX-G
β is the shellside maldistribution correction factor from Figure 5
11. The shellside bundle friction term, HF, needs to be revised to use HF′ to account for the low finned tubes as follows:

 12 (f ) (L) (m)   1 
HF′ = 0.00875     [Fs ] (Customary) Eq. (9)
 (a) (PR) (DEQ) (n)   φ 

 1000 (f ) (L) (m)   1

HF′ = 0.00875     [Fs ] (Metric) Eq. (9)M
 (a) (PR) (DEQ) (n)   φ 

where: Fs is from Table 4 Section IX-D (December, 1995)

Overall Calculations
1. The calculated, clean overall heat transfer coefficient, Uc, as indicated on page 17 of Section IX-D should be revised to
account for the weighted fin efficiency, Ew (obtained from Figure 3 or 3M) as follows:
1
U′c = Eq. (10)
R ′c

where: R′c is defined below:

R ′o
R ′c = R ′io + rw′ + Eq. (11)
Ew

2. The calculated, fouled overall heat transfer coefficient as indicated on page 17 of Section IX-D should be revised to
account for the weighted fin efficiency, Ew (obtained from Figure 3 or 3M) as follows:
1
′ =
UD Eq. (12)
R ′t

where: R′t is defined below:

R ′o
R ′t = R io
′ + rio′ + rw′ + + ro′ Eq. (13)
Ew

SECTION IX-E MODIFICATIONS

Required modifications to the Section IX-E procedure are identified below. See Section IX-E for any undefined nomenclature.

Heat Transfer Calculation Form for Kettle and Internal Reboilers

Exchanger Geometry
1. Equations using inside diameter, di, (e.g. velocity, mass velocity, and Reynolds number) should be revised to use inside
diameter of the low-finned tube, d′i ,where d′i is shown in Figure 1.

2. Ratio of outside to inside surface area, AOl, should be obtained from Table 1 or 1M using AOl′. All equations using AOl
should be revised to use AOl′, to account for the finned surface area.

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CALCULATION PROCEDURE FOR EXTERNAL LOW FIN TUBES (Cont)

Nucleate Boiling Calculations
The design practice for vaporization determines an average shellside boiling coefficient, hab, based on correction factors as
shown on page 22 item 12. The finned tube correction, Ff, already accounts for the difference between bare tube outside
surface and low-finned tube outside surface, Fs, as well as fin efficiency, Fe. When using low-finned tubes, incorporate the
correction factors.
1. Equations using wall resistance, rw ,should be revised to use, rw′ , were:

l [dr + 2 N′f (12 l′ ) (dr + 12 l′ )]

rw′ = (Customary) Eq. (14)
(12) k w ( dr − l )

l [dr + 2 N′f (1000 l′ ) (dr + 1000 l′ )]

rw′ = (Metric) Eq. (14)M
1000 k w dr − l

Heat Transfer Calculation Form for Vertical Tubeside Thermosiphon Reboilers

The annular external finned tubes discussed in this design practice, should not be used in vertical thermosiphon reboilers when
the shellside fluid is condensing. The condensing fluid flowing in the vertical direction does not effectively utilize the external
finned surface area. Other heat transfer enhancement technologies are available, such as the Double Enhanced Tube-Internal
Nucleate Boiling and Shellside Longitudinal Finned Tube shown in Figure 6A Section IX-C (December 1995).

DESIGN PRACTICE IX-F MODIFICATIONS

Required modifications to the Section IX-F procedure are identified below. See Section IX-F for any undefined nomenclature.

I. Zone Duties and Temperatures

1. No modifications required.

II. Shellside Condensation

Note, external annular finned tubes should not be used in vertical shellside condensing applications for reasons indicated in the
previous section.
1. In all equations, the total exchanger area, A , refers to the total (bare plus finned) outside surface area.
2. Equations using inside diameter, di, (e.g. velocity, mass velocity, and Reynolds number) should be revised to use inside
diameter of the low-finned tube, d′i , where d′i is shown in Figure 1.
3. Revise calculation of number of tubes, Nt ,in step 6 on page 22 and step 7 on page 35 of Section IX-F as follows:
As
Nt = (Customary) Eq. (15)
(L − 0.5) AO′

As
Nt = (Metric) Eq. (15)M
(L − 0.0152) AO′

4. All equations using tube inside coefficient referred to the outside area hio should be revised to use tube side inside
coefficient referred to finned area, h′io , where:

 Al′ 
′ = hio 
hio  Eq. (16)
 AO′ 

5. Equations using inside fouling resistance based on outside surface area, rio should be revised to use rio′ , where:

 AO′ 
rio′ = rio   Eq. (17)
 Al′ 

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CALCULATION PROCEDURE FOR EXTERNAL LOW FIN TUBES (Cont)

6. Equations using tube wall resistance rw should be revised to use rw′ where rw′ is calculated as follows:

l [dr + 2 N′f (12 l ′ ) (dr + 12 l ′ )]

rw′ = (Customary) Eq. (18)
(12) k w (d r − l)

l [dr + 2 N′f (1000 l ′ ) (dr + 1000 l ′ )]

rw′ = (Metric) Eq. (18)M
1000 k w (dr − l)

7. Values for Adh, Ads, refer to the outside surface area including the finned area.
8. All shell side heat transfer coefficients calculated per procedures used in Section IX-D should be multiplied by Ew, obtained
from Figure 3 or 3M of this section to correct for fin efficiency.
9. All shell side condensing coefficients (hλ) calculated per Section IX-F should be multiplied by the weighted fin efficiency,
Ew, obtained from Figure 3 or 3M of this section.
10. For Note 1 on page 49, Section IX-F (June, 1994), tube sizes refer to the plain tube end outside diameter, do.
11. Correct maximum area per shell in Note 2 on page 49, Section IX-F (June, 1994) by multiplying the values by:
 AO′   di′ 
    Eq. (19)
 Al′   do 

III. Tubeside Condensation

1. In all equations, the total (bare plus finned) exchanger area, A, refers to the total outside area.
2. Equations using inside diameter, di, (e.g. velocity, mass velocity, and Reynolds number) should be revised to use the inside
diameter of the low-finned tube, di.
3. Calculation for number of tubes, Nt, should be revised as follows:
As
Nt = (Customary) Eq. (20)
(L − 0.5 ) AO′

As
Nt = (Metric) Eq. (20)M
(L − 0.0152) AO′

4. Equations using tube inside heat transfer coefficient referred to the outside area should be revised to use tube inside
coefficient referred to finned area.
5. Equations using inside fouling resistance based on outside surface area, rio, should be revised to use r′io , where:

AO′ 
rio′ = rio   Eq. (21)
 Al′ 
6. Equations using tube wall resistance, rw, should be revised to use r′w where r′w is calculated as follows:

l [dr + 2 N′f (12 l ′ ) (dr + 12 l ′ )]

r w′ = (Customary) Eq. (22)
(12) k w (d r − l)

l [dr + 2 N′f (1000 l ′ ) (dr + 1000 l ′ )]

rw′ = (Metric) Eq. (22)M
1000 k w (dr − l)

7. Values for Adh, Ads, Asc, refer to the outside surface area including the finned area.
8. For Note 1 on page 49, Section IX-F (June, 1994), tube sizes refer to the plain tube end outside diameter, O.D.
9. Correct maximum area per shell in Note 2 on page 49, Section IX-F (June, 1994) by multiplying the values by:
 AO′   d′i 
    Eq. (23)
 Al′   O.D. 

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NOMENCLATURE
a = Tube row spacing factor, dimensionless
A = Bundle outside surface area (bare + finned), ft2 (m2)
As = Surface area per shell, ft2 (m2)
Al′ = Finned tube inside surface area per unit length, ft2 / ft (m2 /m)
AO′ = Finned tube outside surface area per unit length, ft2/ ft (m2 /m)
AOl′ = Finned tube ratio of outside to inside surface area, dimensionless
AT = Single tube outside surface area per unit length, ft2/ ft (m2 /m)
Ax = Free flow area between baffles, ft2 (m2)
BC = Baffle cut as percent of (DS)
(BC)e = Effective baffle cut factor, dimensionless
cp = Specific heat, Btu/lb °F (kJ/kg °C)
di = Unfinned end inside diameter, in. (mm)
d′i = Inside diameter of finned section for low-finned tube, in. (mm)
do = Plain tube end outside diameter, in. (mm)
dr = Root diameter of finned tube, in. (mm)
DEQ = Projected equivalent outside diameter of low finned tubes, in. (mm)
DN = Nominal nozzle I.D., in. (mm)
DOF = Tube outside diameter (over fins), in. (mm)
DOTL = Diameter of bundle outer tube limit, in. (mm)
DS = Shell inside diameter, in. (mm)
DSNI = Shell side inlet nozzle I.D., in. (mm)
DSNO = Shell side outlet nozzle I.D., in. (mm)
DTNI = Tube side inlet nozzle I.D., in. (mm)
DTNO = Tube side outlet nozzle I.D., in. (mm)
Ew = Weighted fin efficiency, dimensionless
f = Non-isothermal friction factor, dimensionless
fis = Isothermal friction factor, dimensionless
Fn = Correction factor for log mean temperature difference, dimensionless
Fs = Shell side pressure drop correction factor, dimensionless
FFBh = Crossflow fraction for heat transfer, dimensionless
FFBp = Crossflow fraction for pressure drop, dimensionless
Gr = Grashof Number, dimensionless
G′xt = Total cross-flow mass velocity with finned tubes, lb/hr ft2 (kg/sm2)
hio = Inside film coefficient based on tube outside surface area, Btu/hr ft2 °F (W/m2 °C)
h′io = Inside film coefficient, corrected to outside finned tube area, Btu/hr ft2 °F (W/m2 °C)

h′o = Outside film coefficient based on finned tube, Btu/hr ft2 °F (W/m2 °C)

HF′ = Finned tube shellside friction term, dimensionless

HM = Shell side momentum term, dimensionless
ji = Stanton number type heat transfer factor, dimensionless
k = Thermal conductivity, Btu/hr ft2 °F (W/m2 °C)
kw = Thermal conductivity of tube wall at average tube temperature, Btu/hr ft2 °F (W/m2 °C)
Ke = Tube side pressure drop coefficient, dimensionless

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NOMENCLATURE (Cont)
L = Tube length, ft (m)
L′ = Tube length between baffles, ft (m)
Le = Effective tube length, ft (m)
LBCC = Central baffle pitch, in. (mm)
LI = Tube flow length, in. (mm)
LMTD = Log mean temperature difference for true counter current flow °F (°C)
l = Tube wall thickness under the fin, in. (mm)
l′ = Fin height, ft (m)
m = Shell side flow factor, dimensionless
MTD = Corrected log mean temperature difference, °F (°C)
n = Baffle spacing to bundle diameter ratio, dimensionless
N = Number of tubes per pass
N′f = Number of fins per unit length, in.-1 (mm-1)
Np = Number of shells in parallel
NT = Total number of shells
Nt = Number of tubes per bundle
NTP = Number of tube passes per shell
NTT′ = Number of finned tubes per bundle
p = Baffle flow factor, dimensionless
Pr = Prandtl number, dimensionless
PR = Tube pitch ratio, dimensionless
PT = Tube pitch, in. (mm)
∆Pe = Tube entrance, expansion, and turnaround pressure drop, psi (kPa)
∆Pexch = Total nozzle to nozzle shell side pressure drop, psi (kPa)
∆Pn = Tube side nozzle pressure drop, psi (kPa)
∆Ps = Shell side pressure drop (excluding nozzles), psi (kPa)
∆Psn = Shell side nozzle pressure drop, psi (kPa)
∆Pt = Tube side frictional pressure drop, psi (kPa)
(∆Pt)nn = Total tube side nozzle pressure drop, psi (kPa)
Q = Rate of heat transfer, Btu/hr (W)
ri = Inside fouling factor referred to tube inside surface area, hr ft2 °F/Btu (m2 °C/W)
rio = Inside fouling factor referred to outside surface area, hr ft2 °F/Btu (m2 °C/W)
rio′ = Inside fouling factor referred to tube outside surface area of low-finned tube, hr ft2 °F/Btu (m2 °C/W)

ro′ = Shell side fouling factor, based on finned tube hr ft2 °F/Btu (m2 °C/W)

rw′ = Resistance of low-finned tube wall at average wall temperature, hr ft2 °F/Btu (m2 °C/W)
RB = Geometry factor, dimensionless
RC = Reynolds number correction factor, dimensionless
R′c = Total resistance (clean) to heat transfer for finned tube, hr ft2 °F/Btu (m2 °C/W)
Re = Reynolds number, dimensionless
Re ′xh = Low-finned tube cross flow Reynolds number for heat transfer, dimensionless

Re ′xp = Low-finned tube cross flow Reynolds number for pressure drop, dimensionless

Re ′xt = Low-finned tube total flow Reynolds number, dimensionless

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NOMENCLATURE (Cont)
R′io = Inside resistance to heat transfer corrected to outside area of low-finned tube , hr ft2 °F/Btu (m2 °C/W)

R′o = Outside film resistance to heat transfer based on low-finned tube, hr ft2 °F/Btu (m2 °C/W)

R′t = Total resistance (duty) to heat transfer based on low-finned tubes, hr ft2 °F/Btu (m2 °C/W)
SC = Baffle spacing correction factor, dimensionless
STT = Tube sheet material allowable stress at design temperature, lb/sq. in. (kPa)
t1 = Inlet temperature of fluid being heated, °F (°C)
t2 = Outlet temperature of fluid being heated, °F (°C)
t′f = Average fin thickness, in. (mm)
T1 = Inlet temperature of fluid being cooled °F (°C)
T2 = Outlet temperature of fluid being cooled, °F (°C)
TDS = Shell side design temperature, °F (°C)
TDT = Tube side design temperature, °F (°C)
TM = Tube sheet design temperature, °F (°C)
TSb = Bulk temperature of shell side fluid, °F (°C)
TSin = Inlet temperature of shell side fluid, °F (°C)
TSout = Outlet temperature of shell side fluid, °F (°C)
TTb = Tube side fluid bulk temperature, °F (°C)
TTin = Inlet temperature of tube side fluid, °F (°C)
TTout = Outlet temperature of tube side fluid, °F (°C)
TTT = Total tube sheet thickness, ft (m)
Tw = Average wall temperature, °F (°C)
∆Ta = Terminal temperature difference, °F (°C)
∆Ts = Shell side temperature difference, °F (°C)
U′c = Overall clean coefficient of heat transfer for low-finned tubes, Btu/hr ft2 °F (W/m2 °C)

U′d = Calculated overall fouled coefficient of heat transfer for low finned tube, Btu/hr ft2, °F (W/m2 °C)
U′o = Overall duty coefficient of heat transfer for low-finned tubes, Btu/hr ft2 °F (W/M2 °C)
Vn = Tube side average nozzle fluid velocity, ft/sec (m/s)
Vt = Fluid velocity in tubes, ft/sec (m/s)
W = Tube side mass rate Lb/hr (kg/s)
Ws = Shell side mass rate, Lb/hr (kg/s)
Xt = Length perpendicular to flow direction across a tube field for a single gap, ft (m) [see HTRI design manual
Volume 1 Figure (2.2.1)]
Yth = Tube side heat transfer correlation factor
αfh = Low finned tube heat transfer correction, dimensionless
β = Heat transfer baffle cut correction, dimensionless
β′ = Coefficient of thermal expansion used in Grashof Number, °F-1 (°C-1)
ε = Short tube laminar flow correction factor, dimensionless
η = Transitional flow heat transfer proration factor, dimensionless
ηf = Theoretical fin efficiency, dimensionless
λ = Tube length correction, dimensionless
γ✶ = Natural convection correction, dimensionless
µb = Viscosity at bulk temperature, cP (mPa s)

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NOMENCLATURE (Cont)
µw = Viscosity at wall temperature, cP (mPa•s)
ρ = Density, lb/ft3 (kg/m3)
φ = Viscosity correction for wall temperature
ψ = Low Prandtl Number correction factor, dimensionless
ψp = Natural convection correction factor, dimensionless
ξ = Baffle correction factor, dimensionless

TABLE 1
PHYSICAL DATA FOR TYPICAL LOW-FINNED TUBES (CUSTOMARY UNITS)

Note: These valves are for scoping purposes only.

• fins per inch = 11
• fin height = 0.117 in.
• fin thickness = 0.011 in.

PLAIN TUBE END FINNED SECTION

WALL
O.D. DOF dr d′′i l′ AO′
(in.)
THICKNESS
(in.) (in.) 2 AO′/Al′
(in.) (in.) (in.) (ft /ft)

0.75 0.058 0.736 0.502 0.452 0.025 0.526 4.51

0.75 0.065 0.736 0.502 0.440 0.031 0.526 4.65
1.00 0.065 0.986 0.752 0.684 0.034 0.743 4.20
1.00 0.072 0.986 0.752 0.674 0.039 0.743 4.28

Note: These valves are for scoping purposes only.

• fins per inch = 19
• fin height = 0.057 in.
• fin thickness = 0.018 in.

PLAIN TUBE END FINNED SECTION

WALL
O.D. DOF dr d′′i l′ AO′
(in.)
THICKNESS
(in.) (in.) 2 AO′/Al′
(in.) (in.) (in.) (ft /ft)

0.75 0.042 0.741 0.627 0.577 0.025 0.508 3.40

0.75 0.047 0.741 0.627 0.565 0.031 0.508 3.48
0.75 0.058 0.741 0.627 0.553 0.037 0.508 3.57
0.75 0.065 0.741 0.627 0.539 0.044 0.508 3.66
0.75 0.083 0.741 0.627 0.511 0.058 0.508 3.90
0.75 0.095 0.741 0.627 0.479 0.074 0.508 4.21
0.75 0.109 0.741 0.627 0.459 0.084 0.508 4.44
1.00 0.058 0.991 0.877 0.803 0.037 0.695 3.35
1.00 0.065 0.991 0.877 0.789 0.044 0.695 3.41
1.00 0.083 0.991 0.877 0.761 0.058 0.695 3.55
1.00 0.095 0.991 0.877 0.729 0.074 0.695 3.73

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TABLE 1 (Cont)
PHYSICAL DATA FOR TYPICAL LOW-FINNED TUBES (CUSTOMARY UNITS)

Note: These valves are for scoping purposes only.

• fins per inch = 28
• fin height = 0.037 in.
• fin thickness = 0.012 in.

PLAIN TUBE END FINNED SECTION

WALL
O.D. DOF dr d′′i l′ AO′
(in.)
THICKNESS
(in.) (in.) 2 AO′/Al′
(in.) (in.) (in.) (ft /ft)

0.75 0.049 0.750 0.676 0.620 0.028 0.521 3.216

0.75 0.065 0.750 0.676 0.578 0.049 0.521 3.450
0.75 0.083 0.750 0.676 0.546 0.065 0.521 3.643
0.75 0.109 0.750 0.676 0.510 0.083 0.521 3.888
1.00 0.049 1.000 0.926 0.870 0.028 0.704 3.088
1.00 0.065 1.000 0.926 0.828 0.049 0.704 3.244
1.00 0.083 1.000 0.926 0.796 0.065 0.704 3.385
1.00 0.109 1.000 0.926 0.760 0.083 0.704 3.538

Note: These valves are for scoping purposes only.

• fins per inch = 36
• fin height = 0.026 in.
• fin thickness = 0.012 in.

PLAIN TUBE END FINNED SECTION

WALL
O.D. DOF dr d′i l′ AO′
(in.)
THICKNESS
(in.) (in.) 2 AO′/Al′
(in.) (in.) (in.) (ft /ft)

0.75 0.049 0.750 0.698 0.642 0.028 0.5 2.98

0.75 0.058 0.750 0.698 0.628 0.035 0.5 3.05
0.75 0.065 0.750 0.698 0.614 0.042 0.5 3.11
0.75 0.072 0.750 0.698 0.600 0.049 0.5 3.19
0.75 0.083 0.750 0.698 0.568 0.065 0.5 3.36
0.75 0.109 0.750 0.698 0.532 0.083 0.5 3.60
1 0.058 1.0 0.948 0.878 0.035 0.671 2.92
1 0.065 1.0 0.948 0.864 0.042 0.671 2.97
1 0.072 1.0 0.948 0.850 0.049 0.671 3.01
1 0.083 1.0 0.948 0.818 0.065 0.671 3.14
1 0.109 1.0 0.948 0.782 0.083 0.671 3.27

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TABLE 1M
PHYSICAL DATA FOR TYPICAL LOW-FINNED TUBES (METRIC UNITS)

Note: These valves are for scoping purposes only.

• fins per meter = 433
• fin height = 2.972 mm
• fin thickness = 0.279 mm

PLAIN TUBE END FINNED SECTION

WALL
O.D. DOF dr d′′i l′ AO′
(mm)
THICKNESS
(mm) (mm) 2 AO′/Al′
(mm) (mm) (mm) (m /m)

19.05 1.473 18.695 12.751 11.481 0.635 0.160 4.51

19.05 1.651 18.695 12.751 11.177 0.787 0.160 4.65
25.4 1.651 25.045 19.101 17.373 0.864 0.226 4.20
25.4 1.829 25.045 19.101 17.121 0.990 0.226 4.28

Note: These valves are for scoping purposes only.

• fins per meter = 748
• fin height = 1.448 m
• fin thickness = 0.457 mm

PLAIN TUBE END FINNED SECTION

WALL
O.D. DOF dr d′′i l′ AO′
(mm)
THICKNESS
(mm) (mm) 2 AO′/Al′
(mm) (mm) (mm) (m /m)

19.05 1.067 18.822 15.926 14.656 0.635 0.155 3.40

19.05 1.194 18.822 15.926 14.352 0.787 0.155 3.48
19.05 1.473 18.822 15.926 14.046 0.940 0.155 3.57
19.05 1.651 18.822 15.926 13.690 1.118 0.155 3.66
19.05 2.108 18.822 15.926 12.980 1.473 0.155 3.90
19.05 2.413 18.822 15.926 12.166 1.880 0.155 4.21
19.05 2.769 18.822 15.926 11.658 2.134 0.155 4.44
25.4 1.473 25.172 22.276 20.396 0.940 0.212 3.35
25.4 1.651 25.172 22.276 20.040 1.118 0.21 3.41
25.4 2.108 25.172 22.276 19.330 1.473 0.212 3.55
25.4 2.413 15.172 22.276 18.516 1.880 0.21 3.73

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
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TABLE 1M (Cont)
PHYSICAL DATA FOR TYPICAL LOW-FINNED TUBES (METRIC UNITS)

Note: These valves are for scoping purposes only.

• fins per meter = 1102
• fin height = 0.94 mm Metric Units
• fin thickness = 0.305 mm

PLAIN TUBE END FINNED SECTION

WALL
O.D. DOF dr d′′i l′ AO′
(mm)
THICKNESS
(mm) (mm) 2 AO′/Al′
(mm) (mm) (mm) (m /m)

19.05 1.245 19.050 17.170 15.748 0.711 0.159 3.216

19.05 1.651 19.050 17.170 14.680 1.245 0.159 3.450
19.05 2.108 19.050 17.170 13.686 1.651 0.159 3.643
19.05 2.769 19.050 17.170 12.954 2.108 0.159 3.888
25.4 1.245 25.400 23.520 22.098 0.711 0.215 3.088
25.4 1.651 25.400 23.520 21.030 1.245 0.215 3.244
25.4 2.108 25.400 23.520 20.218 1.651 0.215 3.385
25.4 2.769 25.400 23.520 19.304 2.108 0.215 3.538

Note: These valves are for scoping purposes only.

• fins per meter = 1417
• fin height = 0.66 mm
• fin thickness = 0.30 mm

PLAIN TUBE END FINNED SECTION

WALL
O.D. DOF dr d′′i l′ AO′
(mm)
THICKNESS
(mm) (mm) 2 AO′/Al′
(mm) (mm) (mm) (m /m)

19.05 1.245 19.05 17.729 16.307 0.711 0.152 2.98

19.05 1.473 19.05 17.729 15.951 0.889 0.152 3.05
19.05 1.651 19.05 17.729 15.596 1.067 0.152 3.11
19.05 1.829 19.05 17.729 15.240 1.245 0.152 3.19
19.05 2.108 19.05 17.729 14.427 1.651 0.152 3.36
19.05 2.769 19.05 17.729 13.513 2.108 0.152 3.60
25.4 1.473 25.4 24.079 22.301 0.889 0.205 2.92
25.4 1.651 25.4 24.079 21.946 1.067 0.205 2.97
25.4 1.829 25.4 24.079 21.590 1.245 0.205 3.01
25.4 2.108 25.4 24.079 20.777 1.651 0.205 3.14
25.4 2.769 25.4 24.079 19.863 2.108 0.205 3.27

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TABLE 2
FINS DIMENSIONS FOR VARIOUS TUBE MATERIALS (CUSTOMARY)

Note: This table lists the common range of fin dimensions for various tube materials. The fin height and thickness depends on
the tube material, fin spacing, and the manufacturer.

NUMBER OF FINS TYPICAL FIN THICKNESS TYPICAL HEIGHT

MATERIAL
PER INCH (in.) (in.)
Carbon Steel 11,19✶, 26, 36 0.010 – 0.013 0.035 – 0.059
Copper Alloys (e.g., Admiralty) 19,26,40 0.0070 – 0.012 0.056 – 0.059
Nickel Alloys 28,30,36 0.011 – 0.012 0.026 – 0.035
Austenitic Stainless Steels (e.g., Type 304,316) 16,26,28 0.010 – 0.016 0.035 – 0.059
Ferritic Stainless Steels (e.g., Type 405,430) 26 0.011 – 0.013 0.049 – 0.052
Titanium 30,32,36,43 0.010 – 0.016 0.022 – 0.032
✶
Most common.

TABLE 2M
FINS DIMENSIONS FOR VARIOUS TUBE MATERIALS (METRIC)

Note: This table lists the common range of fin dimensions for various tube materials. The fin height and thickness depends on
the tube material, fin spacing, and the manufacturer.

NUMBER OF FINS TYPICAL FIN THICKNESS TYPICAL HEIGHT

MATERIAL
PER METER (mm) (mm)
Carbon Steel 433,748,1024,1417 0.25 – 0.33 0.89 – 1.5
Copper Alloys (e.g., Admiralty) 748,1024,1575 0.18 – 0.30 1.42 – 1.5
Nickel Alloys 1102,1181,1417 0.28 – 0.30 0.66 – 0.89
Austenitic Stainless Steels (e.g., Type 304,316) 630,1024,1102 0.25 – 0.41 0.89 – 1.5
Ferritic Stainless Steels (e.g., Type 405,430) 1024 0.28 – 0.33 1.24 – 1.32
Titanium 1181,1260,1417,1693 0.25 – 0.41 0.56 – 0.81

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FIGURE 1
SKETCH OF A LOW FINNED TUBE SHOWING
TYPICAL CROSS-SECTION AND GEOMETRY

tf
l′

do d'i dr DOF

DP9Gf01

Note: All primed symbols refer to low finned tube.

FIGURE 2
HEAT TRANSFER COEFFICIENT CORRECTION FOR LOW-FINNED TUBES

1.0
Low-Finned Tube Heat Transfer Correction, α fh

7.0
5.0
4.0

2.0

1.0
0.7
0.5
0.4
0.3

0.2

0.1
1 2 3 4 5 6 7 101 2 3 4 5 6 7 102 2 3 4 5 6 7 103 2 3 4 5 6 7 104 2 3 4 5 6 7 105

Effective Heat Transfer Reynolds Number, Re′xh DP9GF02

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FIGURE 3
WEIGHTED FIN EFFICIENCIES FOR LOW-FINNED TUBES (CUSTOMARY UNITS)

Kw = 117 Kw = 223
Kw = 9 Kw = 26 Kw = 64
0.99 0.99

0.98 0.98
Cop
per
Weighted Fin Efficiency, Ew

0.95 Alu 0.95

min
um
Adm
iralt
0.90 y 0.90

C. S
teel
0.80 0.80
Sta
inle
ss
0.70 0.70

0.60 0.60

0.50 0.50

0.40 0.40
10 20 30 40 50 70 100 200 300 400 500 700 1000

1
+ ro
ho DP9Gf03

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FIGURE 3M
WEIGHTED FIN EFFICIENCIES FOR LOW-FINNED TUBES (METRIC UNITS)

Kw = 111 Kw = 202 Kw = 386

0.99
Kw = 45
0.98
Kw = 156 Cop
per
Weighted Fin Efficiency, Ew

Alu
min
0.95 um
Adm
iralt
y
0.90
C. S
tee
l
0.80 Sta
inle
ss

0.70

0.60

0.50

0.40
100 200 300 400 500 700 1000 2000 3000 4000 5000 7000 10,000

1
+ ro DP9Gf3M
ho

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FIGURE 4
PRESSURE DROP CORRECTION FOR LOW-FINNED TUBES

2.0

1.9
Low-Finned Tube Pressure Drop Correction, α fp

1.8

1.7

1.6

1.5

1.4

1.3

1.2

1.1

1.0
1 2 3 4 5 6 7 8 102 2 3 4 5 6 7 8 103 2 3 4 5 6 7 8 104

′ xp
Crossflow Reynolds Number, Re
DP9Gf04

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FIGURE 5
SHELL SIDE MALDISTRIBUTION CORRECTION

1.0

(RB)
0.1
Shellside Maldistribution

0.9
0.08
Correction, β

0.06
0.8
0.04

0.02
0.7

Use 0.6 Min. Do Not Extrapolate 0.01

0.6
5 10 20 30 40 50

Effective Baffle Cut, (BC)e, Percent

DP9GfB

Note: β = Correction Factor Reflecting Heat Transfer Inefficiency caused by recirculating eddies due to very small baffle
cuts or to small baffle cut overlap and large shell diameter.

β is given as a function of the effective baffle cut factor (BC)e and a geometry factor (RB) which are defined as follows:
(BC)e = X (BC)

 (PT)   (LBCC) 
(RB) = X 2    
 (DS)   (DS) 

X = 1 for segmental baffles,

= 2 for double-segmental baffles for which if (BC)e is calculated greater than 50,
use (BC)e = 50

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APPENDIX A-1

ESTIMATION METHOD CALCULATION FORM (CUSTOMARY UNITS)

SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
PROCESS ______________ REFINERY AND LOCATION ______________ CALC. BY____________
EXCHANGER NO. E ______________ DATE ____________
1. Terminal Conditions and MTD
Fluid Being Cooled T1 = ________, T2 = ________, T1 – T2 = ________, T1 − T2
R = = ________
t 2 − t1
Fluid Being Heated t2 = ________, t1 = ________, t 2 – t1 = ________, t 2 − t1
j = = ________
T1 − t1
T1 – t2 = ________, T2 – t1 = ________, T1 – t1 = ________
LMTD (T1 − t 2 ) − (T2 − t1) = ________°F
=
(T − t2 )
ln 1
(T2 − t1)
Ns Np
Fn = ________ for ________ shells in series ________ shells in parallel
(Figure 2 in IX-D, ________ for ________ shells in series ________ shells in parallel
December 1995)
________ for ________ shells in series ________ shells in parallel
MTD = Fn (LMTD) = ( ) ( ) = ________°F
= ( ) ( ) = ________°F
2. Bulk Temperatures
Tube side (Heated) TTin = ________, TTout = ________°F
Fluid (Cooled)
TTin + TTout = ________°F
TTb =
2
Shell side (Heated) TSin = ________, TSout = ________°F
Fluid (Cooled)
TSin + TSout = ________°F
TSb =
2

Estimated wall temperature Tw = TTb + 0.6 (TSb – TTb) ________°F

3. Properties of Fluids
Tubes Shell
ρ = __________________ lb/ft3 __________________ lb/ft3
µb = __________________ cP __________________ cP
cp = __________________ Btu/lb °F __________________ Btu/lb °F
k = __________________ Btu/hr ft2 °F/ft __________________ Btu/hr ft2
°F/ft
µw = __________________ cP __________________ cP

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APPENDIX A-1 (Cont)

ESTIMATION METHOD CALCULATION FORM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
4. Flow Rates and Name of Fluids
Tubes Shell
Fluid
Name / Phase = __________/__________ __________/__________
Total Mass Rate __________________ lb/hr _________________ lb/hr
W = Total mass rate/Np = __________________ lb/hr Ws = Total mass rate/NP = _________________ lb/hr
5. Fouling Factors
ri = __________________ hr ft2 °F/Btu
r′o = __________________ hr ft2 °F/Btu
6. Mechanical Design Features
TEMA Type: ___ ___ ___ Tubes Shell
Design Temperature = __________________ °F _________________ °F
Design Pressure = __________________ psig _________________ psig
Nozzle Size DTNI = __________________ in. DSNI = _________________ in.
DTNO = __________________ in. DSNO = _________________ in.
7. Exchanger Geometry
First Trial Second Trial Third Trial
Tube O.D. (do), in. = _______________ ________________ _______________
Tube I.D. ( d′i ), in. = _______________ ________________ _______________

Tube pitch (PT), in. = _______________ ________________ _______________

dr − d′i
Tube wall thickness (l ) in. = = _______________ ________________ _______________
2
Tube length (L), ft = _______________ ________________ _______________
Tube flow length (LI), in. = _______________ ________________ _______________
LI = (24) L for U tubes
LI = (12) L for all others
TEMA exchanger type = _______________ ________________ _______________
Single tube area/length AT, ft2/ft = _______________ ________________ _______________
AT = AO′ from (Table 1) in IX-G
Baffle spacing (LBCC), in. = _______________ ________________ _______________
Tube length between baffle (L′), ft = _______________ ________________ _______________
Baffle type (Segmental or Double Segmental) = _______________ ________________ _______________
Shell inside diameter (DS), in. = _______________ ________________ _______________
Bundle diameter (DOTL), in. = _______________ ________________ _______________
Number of tube side passes (NTP) = _______________ ________________ _______________
(for U tubes minimum number is 2)
8. Iteration, Tube Side
a. Heat duty = Q, Btu/hr = _______________ ________________ _______________
b. Assumed value of U′o , Btu/hr ft2 °F = _______________ ________________ _______________

c. A = Q / U′o (MTD), ft2 = _______________ ________________ _______________

d. As = A/NT, ft2 = _______________ ________________ _______________

e. Tube metal = _____, kw = _____, DOF = _____, in. d′i = _____ in., l′ = _____ ft, L = _____ ft, l = _____ in.

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APPENDIX A-1 (Cont)

ESTIMATION METHOD CALCULATION FORM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
f. Tube pitch (PT) and layout = _______________ ________________ _______________
hr ft 2 oF = _______________ _______________ _______________
g. rio′ = (AO′ / Al′) ri,
Btu

l [dr + 2 N′f (12 l ′ ) (dr + 12 l ′ ) hr ft 2 oF

h. rw′ = ,
12 k w (d r − l) Btu
= _______________ _______________ _______________
i. NTT′ = _______________ _______________ _______________
j. N = NTT′/NTP = _______________ _______________ _______________
W = _______________ _______________ _______________
k. Vt = , ft/s
19.625 ρ N (d′i ) 2
l. Heat Transfer Coefficient
6.32 W 124 ρ Vt (di′ ) = _______________ _______________ _______________
(1) Re ′ = =
µ b (di′ ) N µb
(2) For Water
0.26
368 ( Vt ) 0.7  TTb  Btu
′ =
hio   ,
 AO′   100  hr ft 2 oF
(di′ ) 0.3  
 Al′ 
= _______________ _______________ _______________
(3) Fluids other than water = _______________ _______________ _______________
2.42 c p µb = _______________ _______________ _______________
(a) Pr =
k
(b) If Re ≥ 10,000 = _______________ _______________ _______________
0.264 0.8 0.4 p  AO′  Btu
′ =
hio R e Pr φ /  
di′  Al′  hr ft 2 oF
= _______________ _______________ _______________
φP = (µb/µw)0.167 for liquids = _______________ _______________ _______________
0.5 = _______________ _______________ _______________
 TT + 460 
=  b  for heating gases
 Tw + 460 
 
= 1.0 for cooling gases = _______________ _______________ _______________

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APPENDIX A-1 (Cont)

ESTIMATION METHOD CALCULATION FORM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
(c) If Re < 10,000 = _______________ _______________ _______________
(1) ∆T = Tw – TTb, °F = _______________ _______________ _______________
1 1
−
ρx ρy = _______________ _______________ _______________
(2) β′ =
 1 
( t x − t y )  

 ρ av 
 (d′ ) 3 ρ 2 β′ ∆T 
(3) Gr = 4.13 (10)4  i  = _______________ _______________ _______________
 (µ b ) 2 

(d) If Re ≤ 2000 = _______________ _______________ _______________

(1) From Figure 1.5 in IX-D, = _______________ _______________ _______________
December, 1995 determine λ✶
(2) From Figure 1.6 in IX-D, = _______________ _______________ _______________
December 1995 determine ε
(3) λ = d′i / Ll + ε = _______________ _______________ _______________

(4) From Figure 1.7 in IX-D, = _______________ ________________ _______________

December 1995 determine Ψ
 0.14 
12 k   µb   AO′ Btu
2.5 + 4.5 [R e + λ *]
0.37
(5) ′ =
hio Pr 0.17   ψ ,
d′i   µw   Al′ hr ft 2 oF

= _______________ ________________ _______________
(e) If 2000 < Re < 10,000 = _______________ ________________ _______________
Btu
(1) ( h′io )turb @ Re = 10,000 [from (b)],
hr ft 2 oF
= _______________ ________________ _______________
Btu
(2) ( h′io )iam @ Re = 2,000 [from (d)],
hr ft 2 oF
= _______________ ________________ _______________
(3) η = 1.25 – Re/8000 = _______________ ________________ _______________
Btu
(4) h′io = η ( h′io )iam + (1 – η) ( h′io )turb,
hr ft 2 oF
= _______________ ________________ _______________
(f) Tw = TTb + Uo ( R′io + rio′ ) (TSb – TTb), °F
= _______________ ________________ _______________
(g) Evaluate (µb / µw)0.14 for laminar flow
or φP for turbulent flow and make
necessary corrections to heat transfer = _______________ ________________ _______________
coefficients

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APPENDIX A-1 (Cont)

ESTIMATION METHOD CALCULATION FORM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
m. Pressure Drop
(1) Nozzle Pressure Drop,
0.051 W = ________________ ________________ _______________
(a) Vn = , ft/s
(DTNI) (DTNO ) ρ

ρ Vn2 = ________________ ________________ _______________

(b) ∆Pn = , psi
5152
(2) Entrance, Expansion, and Turn-around
(a) From Table 4 in IX-D determine Ke = ________________ ________________ _______________
Ke ρ Vt2
(b) ∆Pe = , psi = ________________ ________________ _______________
9274
(3) Frictional Pressure Drop
(a) From Figure 1.8 in IX-D, December = ________________ ________________ _______________
1995 evaluate fis
(b) From Figure 1.9 in IX-D, December = ________________ ________________ _______________
1995 evaluate φ
(c) From Figure 1.10 in IX-D, December = ________________ ________________ _______________
1995 evaluate ψp
(d) f = fis φ ψp = ________________ ________________ _______________
2
5.19 [ ρ ( Vt ) (NTP) L ]
(e) ∆Pt = f , psi = ________________ ________________ _______________
10 3 d′i
(4) (∆Pt)nn = Ns [∆Pn + ∆Pe + (Ft) (∆Pt)], psi = ________________ ________________ _______________
get value of Ft from Table 4 in IX-D,
December 1995
9. Iteration, Shell Side
Tube row spacing factor
a = 1.0 for Square Pitch
a = 0.867 for all others = _______________ _______________ ______________
DEQ = dr + [DOF – dr] N′f ( t′f ), in. = _______________ _______________ ______________

Pitch Ratio (PR) = PT/DEQ = _______________ _______________ ______________

Baffle Space to Bundle Diameter ratio (n)
n = LBCC / DOTL = _______________ _______________ ______________
Shell side flow factor (m)
m = 0.5 for J shell
m = 2.0 for F shell
m = 1.0 for E shell
Baffle flow factor (p)
p = 1.0 for segmental baffles
p = 0.5 for double-segmental baffles = _______________ _______________ ______________
Baffle Correction factor (ξ)
ξ = 1.0 for segmental baffles
ξ = 0.8 for double-segmental baffles = _______________ _______________ ______________

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APPENDIX A-1 (Cont)

ESTIMATION METHOD CALCULATION FORM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
Estimated tube wall temperature (Tw), °F
Tw = TSb – 0.3 (TSb – TTb) = _______________ _______________ ______________
Wall viscosity correction (φ)
0.14
µ 
φ =  b  = _______________ _______________ ______________
 µw 
Total cross flow mass velocity ( G′xt ), lb/hr ft2

 PR   (m) (p)   Ws 
G′xt = 144     = _______________ _______________ ______________
 PR − 1  n   (DOTL )2 

Total flow Reynolds Number ( Re ′xt ),

(DEQ) (G ′xt ) = _______________ _______________ ______________

Re ′xt =
29 µ b
Nominal Crossflow fraction (FFBn) Figure 1.1 in IX-D, = _______________ _______________ ______________
December 1995
Baffle Spacing Correction (SC) Figure 1.2 in IX-D, = _______________ _______________ ______________
December 1995
Reynolds Number Correction (RC) Figure 1.3 in IX-D, = _______________ _______________ ______________
December 1995
Cross flow fraction for pressure drop (FFBp)
FFBp = (FFBn) (SC) (RC) (Maximum = 1.0) = _______________ _______________ ______________
Cross flow Reynolds Number for ∆P ( Re ′xp )

Re ′xp = ( Re ′xt ) (FFBp) = _______________ _______________ ______________

Shell side friction factors (f) Figure 1.4 in IX-D, = _______________ _______________ ______________
December 1995
Cross flow fraction for heat transfer (FFBh)
FFBh = FFBp + 0.125 (Maximum = 1.0) = _______________ _______________ ______________
Cross flow Reynolds Number for heat transfer ( Re ′xh )

Re ′xh = ( Re ′xt ) (FFBh) = ________________ ________________ ______________

Shell side heat transfer factor (j) Figure 1.4 in IX-D, = ________________ ________________ ______________
December 1995
Obtain αfh from Figure 2 in IX-G = ________________ ________________ ______________
Obtain β from Figure 5 of IX-G = ________________ ________________ ______________
Shell side film coefficient ( h′o ) Btu/hr ft2 °F
−2 / 3 0.14
 c p µb   µb 
h′o = 0.415 cp ( G′xt ) (FFBh) (j)  


µ

 β α fh
 k   w 
= ________________ ________________ ______________
Shell side Friction Term (HF′)

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APPENDIX A-1 (Cont)

ESTIMATION METHOD CALCULATION FORM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
 12 ( f ) (L ) (m)   1 
HF′ = 0.00875     (Fs ) = ________________ ________________ ______________
 (a )(PR)(DEQ)(n)   φ 
(Get value of Fs from Table 4 in IX-D, December 1995)
Shell side momentum term (HM)
 (12) (L ) (m) 
HM = 0.00168 (n)2.6  − 1 .0  = ________________ ________________ ______________
 ( n ) (DOTL ) 
Obtain value of αfp from Figure 4 in IX-G
Shell side pressure drop without Nozzle (∆ P′s ), psi
2
(0.3 ) [HF′ + HM]  (G′xt ) (FFBp )   1
∆Ps′ =
ρ
  ξ
( )
  α fp
=________________ ________________ ______________
 10,000   

Nominal shell nozzle I.D. (DN), in.

DN = (DSNI) (DSNO) = ________________ ________________ ______________

Shell side nozzle pressure drop (∆Psn), psi

2
0.84  Ws 
∆Psn =  = ________________ ________________ ______________
ρ 2
 (1000 ) (DN) 
Total shell side pressure drop (∆Pexch), psi
∆Pexch = Ns [∆P′s + ∆Psn] = ________________ ________________ ______________
Calculated Tube wall temp. (Tw), °F
 1.0 
Tw = TSb – Uo   (TS b − TTb ) = ________________ ________________ ______________
 h′o 
Calculate viscosity correction (φ)
0.14
µ  = ________________ ________________ ______________
φ =  b 

 µw 
Using calculated value of φ correct hs and ∆Ps
10. Overall calculations
Inside resistance referred to outside area ( R′io ), hr ft2 °F/Btu
1 = _______________ _______________ ______________
′ =
R io
′
hio
Outside resistance ( R′o ), hr ft2 °F/Btu
1 = _______________ _______________ ______________
R ′o =
h′o
Obtain value of fin efficiency, Ew, from Figure 3 in = _______________ _______________ ______________
IX-G
Total clean resistance ( R′c ), hr ft2 °F/Btu

 R′  = _______________ _______________ ______________

′ +  o
R ′c = R io  + rw′
 Ew 
Calculated overall fouled coefficient ( U′c ), Btu/hr ft2 °F

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
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IX-G 32 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
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APPENDIX A-1 (Cont)

ESTIMATION METHOD CALCULATION FORM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
1 = _______________ _______________ ________________
U′c =
R ′c

Calculated overall clean coefficient ( U′D ), Btu/hr ft2 °F

1
′ =
UD = _______________ _______________ ________________
 R′ 
R ′io + rw′ + rio′ +  o  + ro′
 Ew 
Tubesheet thickness (TTT), ft
(C1) (DS + 2.5 ) (P / STT )0.5 + 1.0 = _______________ _______________ ________________
TTT =
12.0
C1 = 0.625 for u-tubes, 1.0 for all others
P = higher of shell side or tube side design pressure
Effective tube length (Le), ft
Le = L – TTT = _______________ _______________ ________________
Effective heat transfer area per shell (As), ft2
As = (NTT) (Le) (AT) = _______________ _______________ ________________
Total Effective heat transfer area (A), ft 2

A = (As) (NT) = _______________ _______________ ________________

Overall duty coefficient (Uo), Btu/hr ft2 °F
Q
U′o =
( A) (MTD )
U′D − U′o = _______________ _______________ ________________
% Overdesign = x 100
U′o
(Normally required for Copper alloys)
a. For coolers. (Cooling Water on tube side)
i) Clean conditions, °F
′
R io
TM = TDT + [TDS − TDT ] = _______________ _______________ ________________
R ′c
ii) Fouled conditions, °F
′ + rio′ ) (TDS – TDT)
TM = TDT + Uo ( R io = ________________ ________________ ________________

iii) Controlling case, °F

Larger of the clean or fouled = ________________ ________________ ________________
b. For exchangers
i) Tube side fluid being cooled
TM = TDT – 0.1 (TDT – TDS) = ________________ ________________ ________________
ii) Shell side fluid being cooled
TM = TDT + 0.3 (TDS – TDT) = _______________ ________________ ________________

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CALCULATION PROCEDURE, Section Page
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ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-1M

ESTIMATION METHOD CALCULATION FORM (METRIC UNITS)

SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
PROCESS ______________ REFINERY AND LOCATION ______________ CALC. BY____________
EXCHANGER NO. E ______________ DATE ____________
1. Terminal Conditions and MTD
Fluid Being Cooled T1 = ________, T2 = ________, T1 – T2 = ________, T1 − T2
R = =________
t 2 − t1
Fluid Being Heated t2 = ________, t1 = ________, t 2 – t1 = ________, t 2 − t1
j = =________
T1 − t1
T1 – t2 = ________, T2 – t1 = ________, T1 – t1 = ________
LMTD (T1 − t 2 ) − (T2 − t1) = ________°C
=
(T − t2 )
ln 1
(T2 − t1)
Ns Np
Fn = ________ for ________ shells in series ________ shells in parallel
(Figure 2 in IX-D) ________ for ________ shells in series ________ shells in parallel
________ for ________ shells in series ________ shells in parallel
MTD = Fn (LMTD) = ( ) ( ) = ________°C
= ( ) ( ) = ________°C
2. Bulk Temperatures
Tube side (Heated) TTin = ________, TTout = ________°C
Fluid (Cooled)
TTin + TTout = ________°C
TTb =
2
Shell side (Heated) TSin = ________, TSout = ________°C
Fluid (Cooled)
TSin + TSout = ________°C
TSb =
2

Estimated wall temperature Tw = TTb + 0.6 (TSb – TTb) ________°C

3. Properties of Fluids
Tubes Shell
ρ = __________________ kg/m3 __________________ kg/m3
µb = __________________ Pa•s __________________ Pa•s
cp = __________________ kJ/kg °C __________________ kJ/kg °C
k = __________________ W/m °C __________________ W/m °C
µw = __________________ Pa•s __________________ Pa•s
4. Flow Rates and Name of Fluids
Tubes Shell
Fluid
Name / Phase = __________/__________ __________/__________
Total Mass Rate __________________ Kg/s __________________ Kg/s

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
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IX-G 34 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
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APPENDIX A-1M (Cont)

ESTIMATION METHOD CALCULATION FORM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
W = Total mass rate/Np = __________________ Kg/s W s = Total mass rate/NP = ________________ Kg/s
5. Fouling Factors
ri = __________________ m2 °C/W
ro′ = __________________ m2 °C/W
6. Mechanical Design Features
TEMA Type: ___ ___ ___ Tubes Shell
Design Temperature = __________________ °C ________________ °C
Design Pressure = __________________ kPa ________________ kPa
Nozzle Size DTNI = __________________ mm DSNI = ________________ mm
DTNO = __________________ mm DSNO = ________________ mm
7. Exchanger Geometry
First Trial Second Trial Third Trial
Tube O.D. (do), mm = _______________ ________________ ______________
Tube I.D. ( d′i ), mm = _______________ ________________ ______________

Tube pitch (PT), mm = _______________ ________________ ______________

dr − d′i
Tube wall thickness (l) mm = = _______________ ________________ ______________
2
Tube length (L), m = _______________ ________________ ______________
Tube flow length (LI), mm = _______________ ________________ ______________
LI = (24) L for U tubes
LI = (12) L for all others
TEMA exchanger type = _______________ ________________ ______________
Single tube area/length AT, m2/m = _______________ ________________ ______________
AT = AO′ from (Table 1M) in IX-G
Baffle spacing (LBCC), mm = _______________ ________________ ______________
Tube length between baffle (L′), m = _______________ ________________ ______________
Baffle type (Segmental or Double Segmental) = _______________ ________________ ______________
Shell inside diameter (DS), mm = _______________ ________________ ______________
Bundle diameter (DOTL), mm = _______________ ________________ ______________
Number of tube side passes (NTP) = _______________ ________________ ______________
(for U tubes minimum number is 2)
8. Iteration, Tube Side
a. Heat duty = Q, MW = _______________ ________________ ______________
b. Assumed value of U′o , W/m2 °C = _______________ ________________ ______________

c. A = Q/ U′o (MTD), m2 = _______________ ________________ ______________

d. As = A/NT, m2 = _______________ ________________ ______________

e. Tube metal = _____, kw = _____, DOF = _____ mm, d′i = _____ mm, l ′ = _____ m, L = _____ m, l = _____ mm
f. Tube pitch (PT) and Layout = _______________ ________________ ______________
= _______________ ________________ ______________
m oC
2
g. rio′ = (AO′ / Al′) ri,
W

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 HEAT EXCHANGE EQUIPMENT DESIGN PRACTICES
CALCULATION PROCEDURE, Section Page
EXXON LOW-FINNED TUBES IX-G 35 of 56
ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-1M (Cont)

ESTIMATION METHOD CALCULATION FORM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
l [dr + 2 N′f (1000 l ′ ) (dr + 1000 l ′ ) W
h. ′ =
rw ,
1000 k w (dr − l) m2 oC
= _______________ ________________ ______________
i. NTT′ = _______________ ________________ ______________
j. N = NTT′/NTP = _______________ ________________ ______________

W (1.273 x 10 6 = _______________ ________________ ______________

k. Vt = , m/s
2
ρ N (di′ )
l. Heat Transfer Coefficient
1273 W ρ Vt (di′ ) (10 −3 ) = _______________ ________________ ______________
(1) Re ′ = =
µ b (di′ ) N µb
(2) For Water
0.26
(1.27 x 10 4 ) ( Vt ) 0.7  1.8 TTb + 32  W
h′io =   ,
 AO′   100  m oC
2
(d′i ) 0.3  
 Al′ 
= _______________ ________________ ______________
(3) Fluids other than water = _______________ ________________ ______________
c p µb = _______________ ________________ ______________
(a) Pr = (103 )
k
(b) If Re ≥ 10,000 = _______________ ________________ ______________
22 k 0.8 0.4 p  AO′  , W = _______________ ________________ ______________
′ =
hio R e Pr φ /  
di′  Al′  m2 oC
φP = (µb/µw)0.167 for liquids = _______________ ________________ ______________
0.5
 TT + 273 
=  b  for heating gases = _______________ ________________ ______________
 Tw + 273 
 
= 1.0 for cooling gases = _______________ ________________ ______________
(c) If Re < 10,000 = _______________ ________________ ______________
(1) ∆T = Tw – TTb, °C = _______________ ________________ ______________
1 1
−
ρx ρy = _______________ ________________ ______________
(2) β′ =
 1 
( t x − t y )  

 ρ av 
 (d′ ) 3 ρ 2 β′ ∆T 
(3) Gr = (9.82 x 10-9)  i  = _______________ ________________ ______________
 (µ b ) 2 

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
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IX-G 36 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
December, 1999 PROPRIETARY INFORMATION - For Authorized Company Use Only

APPENDIX A-1M (Cont)

ESTIMATION METHOD CALCULATION FORM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
(d) If Re ≤ 2000 = _______________ ________________ ______________
(1) From Figure 1.5 in IX-D = _______________ ________________ ______________
determine λ✶
(2) From Figure 1.6 in IX-D = _______________ ________________ ______________
determine ε
(3) λ = d′i / Ll + ε = _______________ ________________ ______________

(4) From Figure 1.7 in IX-D = _______________ ________________ ______________

determine Ψ
 0.14 
10 3 k   µb   AO′ W
2.5 + 4.5 [(R e + λ *)λ ]
0.37
(5) h′io = Pr0.17   ψ ,
di′   µw   Al′ 2 o
m C

= _______________ ________________ ______________

(e) If 2000 < 10,000 = _______________ ________________ ______________
W
(1) ( h′io )turb @ Re = 10,000 [from (b)],
m oC
2

= _______________ ________________ ______________

W
(2) ( h′io )iam @ Re = 2,000 [from (d)],
m2 oC
= _______________ ________________ ______________
(3) η = 1.25 – Re/8000 = _______________ ________________ ______________
W
(4) h′io = η (h′io )iam + (1 − η) (hio
′ ) turb ,
m oC
2

= _______________ ________________ ______________

′ + rio′ ) (TSb – TTb), °C
(f) Tw = TTb + Uo ( R io
= _______________ ________________ ______________
(g) Evaluate (µb / µw)0.14
for laminar flow
or φP for turbulent flow and make
necessary corrections to heat transfer = _______________ ________________ ______________
coefficients
m. Pressure Drop
(1) Nozzle Pressure Drop,
1.273 W x 106 = ________________ ________________ ______________
(a) Vn = , m/s
(DTNI) (DTNO ) ρ

ρ Vn2 = ________________ ________________ ______________

(b) ∆Pn = , kPa
1112
(2) Entrance, Expansion, and Turn-around
(a) From Table 3 in IX-D determine Ke = ________________ ________________ ______________
K e ρ Vt2
(b) ∆Pe = , kPa = ________________ ________________ ______________
2000

EXXON RESEARCH AND ENGINEERING COMPANY - FLORHAM PARK, N.J.

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CALCULATION PROCEDURE, Section Page
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ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-1M (Cont)

ESTIMATION METHOD CALCULATION FORM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
(3) Frictional Pressure Drop
(a) From Figure 1.8 in IX-D evaluate fis = _______________ ________________ _______________
(b) From Figure 1.9 in IX-D evaluate φ = _______________ ________________ _______________
(c) From Figure 1.10 in IX-D evaluate ψp = _______________ ________________ _______________
(d) f = fis φ ψp = _______________ ________________ _______________
[ ρ ( Vt ) 2 (NTP) L ]
(e) ∆Pt = 2 f , kPa = _______________ ________________ _______________
d′i
(4) (∆Pt)nn = Ns [∆Pn + ∆Pe + (Ft) (∆Pt)], kPa = _______________ ________________ ______________
get value of Ft from Table 4 in IX-D,
December 1995
9. Iteration, Shell Side
Tube row spacing factor
a = 1.0 for Square Pitch
a = 0.867 for all others = _______________ ________________ ______________
DEQ = dr + [DOF – dr] N′f (t ′f ) , mm = _______________ ________________ ______________

Pitch Ratio (PR) = PT/DEQ = _______________ ________________ ______________

Baff. Space to Bundle Dia ratio (n)
n = LBCC / DOTL = _______________ ________________ ______________
Shell side flow factor (m)
m = 0.5 for J shell
m = 2.0 for F shell
m = 1.0 for E shell
Baffle flow factor (p)
p = 1.0 for segmental baffles
p = 0.5 for double-segmental baffles = _______________ ________________ ______________
Baffle Correction factor (ξ)
ξ = 1.0 for segmental baffles
ξ = 0.8 for double-segmental baffles = _______________ ________________ ______________
Estimated tube wall temperature (Tw), °C
Tw = TSb – 0.3 (TSb – TTb) = _______________ ________________ ______________
Wall viscosity correction (φ)
0.14
µ 
φ =  b  = _______________ ________________ ______________
 µw 
Total cross flow mass velocity ( G′xt ), kg/s m2

 PR   (m) (p)   Ws 
G′xt = 106     = _______________ ________________ ______________
 PR − 1  n   (DOTL )2 

Total flow Reynolds Number ( Re ′xt ),

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APPENDIX A-1M (Cont)

ESTIMATION METHOD CALCULATION FORM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
−3
(DEQ) (G′xt ) (10 )
R ′ext = = _______________ ________________ ______________
µb
Nominal Crossflow fraction (FFBn) Figure 1.1 in IX-D, = _______________ ________________ ______________
December 1995
Baffle Spacing Correction (SC) Figure 1.2 in IX-D, = _______________ ________________ ______________
December 1995
Reynolds Number Correction (RC) Figure 1.3 in IX-D, = _______________ ________________ ______________
December 1995
Cross flow fraction for pressure drop (FFBp)
FFBp = (FFBn) (SC) (RC) (Maximum = 1.0) = _______________ ________________ ______________
Cross flow Reynolds Number for ∆P ( Re ′xp )

Re ′xp = (Re ′xt ) (FFBp) = _______________ ________________ ______________

Shell side friction factor (f) Figure 1.4 in IX-D, = _______________ ________________ ______________
December 1995
Cross flow fraction for heat transfer (FFBh)
FFBh = FFBp + 0.125 (Maximum = 1.0) = _______________ ________________ ______________
Cross flow Reynolds Number for heat transfer ( Re ′xh )

Re ′xh = (Re ′xt ) (FFBh) = _______________ ________________ ______________

Shell side heat transfer factor (j) Figure 1.4 in IX-D = _______________ ________________ ______________
Obtain αfh from Figure 2 in IX-G = _______________ ________________ ______________
Obtain β from Figure 5 in IX-G = _______________ ________________ ______________
Shell side film coefficient ( h′o ) W/m2 °C
−2 / 3 0.14
 c p µb   µb 
h′o = 7.5 c p (G′xt ) (FFB h ) ( j)  

  β α fh
 k   µw 
= ________________ ________________ ______________
Shell side Friction Term (HF′)
 1000 ( f ) (L ) (m)   1 
HF′ = 0.00875     (Fs ) = ________________ ________________ ______________
 (a )(PR)(DEQ)(n)   φ 
(Get value of Fs from Table 4 in IX-D)
Shell side momentum term (HM)
 (1000 ) (L ) (m) 
HM = 0.00168 (n)2.6  − 1. 0  = ________________ ________________ ______________
 ( n ) (DOTL ) 
Obtain value of αfp from Figure 4 in IX-G
Shell side pressure drop without Nozzle (∆Ps), kPa
2
(0.3) [HF′ + HM]  (G′xt ) (FFB p )   1
∆Ps′ =
ρ
    α fp
ξ
( ) =________________ ________________ ______________
 10,000   
Nominal shell nozzle I.D. (DN), mm
DN = (DSNI) (DSNO) = ________________ ________________ ______________

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ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-1M (Cont)

ESTIMATION METHOD CALCULATION FORM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
Shell side nozzle pressure drop (∆Psn), kPa
2
24.31  Ws (10 4 ) 
∆Psn =   = ________________ ________________ _______________
ρ 2
 (DN) 
Total shell side pressure drop (∆Pexch), kPa
∆Pexch = Ns [∆ P′s + ∆Psn] = ________________ ________________ ______________

Calculated Tube wall temp. (Tw), °C

 1.0 
Tw = TSb – U′o   (TS b − TTb ) = ________________ ________________ _______________
 h ′o 
Calculate viscosity correction (φ)
0.14
µ  = ________________ ________________ _______________
φ =  b 

 µw 
Using calculated value of φ correct hs and ∆Ps
10. Overall calculations
Inside resistance referred to outside area ( R′io ), hr m2 °C/W
1
′ =
R io = ________________ ________________ _______________
′
hio

Outside resistance ( R′o ), m2 °C/W

R ′o = 1/ h′o = ________________ ________________ _______________

Obtain value of fin efficiency, Ew, from Figure 3M in IX-G = ________________ ________________ _______________
Total clean resistance ( R′c ), m2 °C/W

 R′ 
′ +  o
R ′c = R io  + rw′ = ________________ ________________ _______________
 Ew 
Calculated overall clean coefficient ( U′c ), W/m2 °C
1
U′c = = ________________ ________________ _______________
R ′c
Calculated overall clean coefficient ( U′D ), W/m2 °C
1
′ =
UD = ________________ ________________ _______________
 R′ 
R ′io + rw′ + rio′ +  o  + ro′
 Ew 
Tubesheet thickness (TTT), ft
(C1) (DS + 64 ) (P / STT )0.5 + 25.0
TTT = = ________________ ________________ _______________
1000
C1 = 0.625 for u-tubes, 1.0 for all others
P = higher of shell side or tube side design pressure
Effective tube length (Le), m
Le = L – TTT = ________________ ________________ _______________
Effective heat transfer area per shell (As), ft2

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IX-G 40 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
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APPENDIX A-1M (Cont)

ESTIMATION METHOD CALCULATION FORM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
As = (NTT) (Le) (AT) = _______________ ________________ _______________
Total Effective heat transfer area (As), m2
A = (As) (NT) = _______________ ________________ _______________
Overall duty coefficient (Uo), w/m2 °C
Q
U′o =
( A) (MTD )
U′D − U′o
% Overdesign = x 100 = _______________ ________________ _______________
U′o
(Normally required for Copper alloys)
Tubesheet Temperature, TM:
a. For coolers. (Cooling Water on tube side)
i) Clean conditions, °C
′
R io
TM = TDT + [TDS − TDT ] = ______________ ________________ _______________
R ′c
ii) Fouled conditions, °C
′ + rio′ ) (TDS – TDT)
TM = TDT + Uo ( R io = _______________ ________________ _______________

iii) Controlling case, °C

Larger of the clean or fouled = _______________ ________________ _______________
b. For exchangers
i) Tube side fluid being cooled
TM = TDT – 0.1 (TDT – TDS) = _______________ ________________ _______________
ii) Shell side fluid being cooled
TM = TDT + 0.3 (TDS – TDT) = _______________ ________________ _______________

EXXON RESEARCH AND ENGINEERING COMPANY - FLORHAM PARK, N.J.

 HEAT EXCHANGE EQUIPMENT DESIGN PRACTICES
CALCULATION PROCEDURE, Section Page
EXXON LOW-FINNED TUBES IX-G 41 of 56
ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-2

EXAMPLE PROBLEM (CUSTOMARY UNITS)

SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
PROCESS ______________ REFINERY AND LOCATION ______________ CALC. BY ____________
EXCHANGER NO. E – 001_________ DATE ____________
1. Terminal Conditions and MTD
Fluid Being Cooled T1 = __193___, T2 = __137___, T1 – T2 = ___53___, T1 − T2
R = = ____1.93
t 2 − t1
Fluid Being Heated t2 = __117.5_, t1 = ___90___, t2 – t1 = ___27.5_, t 2 − t1
j = = ____0.275
T1 − t1
T1 – t2 = ___72.5_, T2 – t1 = ___47___, T1 – t1 = __100___
LMTD (T1 − t 2 ) − (T2 − t1) = ___58.83°F
=
(T − t2 )
ln 1
(T2 − t1)
Ns Np
Fn = ____0.92 for ____1___ shells in series ____1___ shells in parallel
(Figure 2 in IX-D, ________ for ________ shells in series ________ shells in parallel
December 1995)
________ for ________ shells in series ________ shells in parallel
MTD = Fn (LMTD) = ( 0.92 ) ( 58.83 ) = __54.12_°F
= ( ) ( ) = ________°F
2. Bulk Temperatures
Tube side (Heated) TTin = ___90__, TTout = __117.5_°F
Fluid (Cooled)
TTin + TTout = __103.75°F
TTb =
2
Shell side (Heated) TSin = __190___, TSout = __137___°F
Fluid (Cooled)
TSin + TSout = __163.5_°F
TSb =
2

Estimated wall temperature Tw = TTb + 0.6 (TSb – TTb) __139.6_°F

3. Properties of Fluids
Tubes Shell
ρ = _______61.82______ lb/ft3 ________0.358_____ lb/ft3
µb = ________0.657_____ cP ________0.0129____ cP
cp = ________0.998_____ Btu/lb °F ________0.571_____ Btu/lb °F
k = ________0.367_____ Btu/hr ft2 °F/ft ________0.024_____ Btu/hr ft2 °F/ft
µw = ________0.605_____ cP ________0.0126____ cP

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
Section Page CALCULATION PROCEDURE,
IX-G 42 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
December, 1999 PROPRIETARY INFORMATION - For Authorized Company Use Only

APPENDIX A-2 (Cont)

EXAMPLE PROBLEM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
4. Flow Rates and Name of Fluids
Tubes Shell
Fluid
Name / Phase = _Water____/_Liquid__ __Methane_/__Vapor
Total Mass Rate ______74,000______ lb/hr ______67,000_____ lb/hr
W = Total mass rate/Np = ______74,000______ lb/hr Ws = Total mass rate/NP = ______67,000______ lb/hr
5. Fouling Factors
ri = ________0.002_____ hr ft2 °F/Btu
ro′ = ________0.001_____ hr ft2 °F/Btu
6. Mechanical Design Features
TEMA Type: AJL Tubes Shell
Design Temperature = _______300________ °F ______300________ °F
Design Pressure = _______300________ psig ______300________ psig
Nozzle Size DTNI = _________3.07_____ in. DSNI = ________12.09_____ in.
DTNO = _________3.07_____ in. DSNO = ________12.09_____ in.
7. Exchanger Geometry
First Trial Second Trial Third Trial
Tube O.D. (do), in. = ________0.75____ ________________ _______________
Tube I.D. ( d′i ), in. = ________0.459___ ________________ _______________

Tube pitch (PT), in. = ________0.9375__ ________________ _______________

dr − di′
Tube wall thickness (l) in. = = ________0.084___ ________________ _______________
2
Tube length (L), ft = _______16.0_____ ________________ _______________
Tube flow length (LI), in. = ______192.0_____ ________________ _______________
LI = (24) L for U tubes
LI = (12) L for all others
TEMA exchanger type = _______AJL_____ ________________ _______________
Single tube area/length AT, ft2/ft = ________0.508___ ________________ _______________
AT = AO′ from (Table 1) in IX-G
Baffle spacing (LBCC), in. = _______15.68____ ________________ _______________
Tube length between baffle (L′), ft = ________1.307___ ________________ _______________
Baffle type (Segmental or Double Segmental) = _______SEG_____ ________________ _______________
Shell inside diameter (DS), in. = _______15.25____ ________________ _______________
Bundle diameter (DOTL), in. = _______14.0_____ ________________ _______________
Number of tube side passes (NTP) = ________2______ ________________ _______________
(for U tubes minimum number is 2)
8. Iteration, Tube Side
a. Heat duty = Q, Btu/hr = ____2,030,600___ ________________ _______________
b. Assumed value of U′o , Btu/hr ft2 °F = _______45.7_____ ________________ _______________

c. A = Q/Uo (MTD), ft2 = ______821______ ________________ _______________

d. As = A/NT, ft2 = ______821______ ________________ _______________
e. Tube metal = _CS__, kw = _29.6, DOF = 0.741 in., d′i = 0.459 in., l ′ = 0.00475 ft, L = _16.0 ft, l = 0.084 in.

EXXON RESEARCH AND ENGINEERING COMPANY - FLORHAM PARK, N.J.

 HEAT EXCHANGE EQUIPMENT DESIGN PRACTICES
CALCULATION PROCEDURE, Section Page
EXXON LOW-FINNED TUBES IX-G 43 of 56
ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-2 (Cont)

EXAMPLE PROBLEM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
f. Tube pitch (PT) and Layout = _(0.9375) 30° ∆___ ________________ _______________
= ________0.00888_ ________________ _______________
hr ft 2 oF
g. rio′ = (AO′ / Al′) ri,
Btu

l [dr + 2 N′f (12 l ′ ) (dr + 12 l ′ ) hr ft 2 oF

h. rw′ = ,
12 k w (d r − l) Btu

= ________0.00092_ ________________ _______________

i. NTT′ = ______102______ ________________ _______________
j. N = NTT′/NTP ________________ _______________
W
k. Vt = , ft/s = ________5.67____ ________________ _______________
19.625 ρ N (d′i ) 2
l. Heat Transfer Coefficient
6.32 W 124 ρ Vt (di′ )
(1) Re ′ = = = ___30,400_______ ________________ _______________
µ b (di′ ) N µb
(2) For Water
0.26
368 ( Vt )0.7  TTb  Btu
h′io = ,
 AO′   100  hr ft 2 oF
(d′i )0.3  
 Al′ 
= ______357______ ________________ _______________
(3) Fluids other than water = _______________ ________________ _______________
2.42 c p µb
(a) Pr = = _______________ ________________ _______________
k
(b) If Re ≥ 10,000 = _______________ ________________ _______________
0.264 0.8 0.4 p  AO′  Btu
′ =
hio R e Pr φ /  ,
di′  Al′  hr ft 2 oF

= _______________ ________________ _______________

φP = (µb/µw)0.167 for liquids = _______________ ________________ _______________
0.5
 TT + 460 
=  b  for heating gases = _______________ ________________ _______________
 Tw + 460 
 
= 1.0 for cooling gases = _______________ ________________ _______________
(c) If Re < 10,000 = _______________ ________________ _______________
(1) ∆T = Tw – TTb, °F = _______________ ________________ _______________
1 1
−
ρx ρy
(2) β′ = = _______________ ________________ _______________
 1 
(t x − t y )  

 ρ av 

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
Section Page CALCULATION PROCEDURE,
IX-G 44 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
December, 1999 PROPRIETARY INFORMATION - For Authorized Company Use Only

APPENDIX A-2 (Cont)

EXAMPLE PROBLEM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
 (d′ ) ρ β′ ∆T 
3 2
(3) Gr = 4.13 (10)4  i  = _______________ ________________ _______________
 (µ b ) 2 

(d) If Re ≤ 2000 = _______________ ________________ _______________

(1) From Figure 1.5 in IX-D, = _______________ ________________ _______________
(December 1995) determine λ✶
(2) From Figure 1.6 in IX-D, = _______________ ________________ _______________
(December 1995) determine ε
(3) λ = d′i / Ll + ε = _______________ ________________ _______________

(4) From Figure 1.7 in IX-D, = _______________ ________________ _______________

(December 1995) determine Ψ
 0.14 
12 k   µb   AO′ Btu
2.5 + 4.5 [R e + λ *]
0.37
(5) h′io = Pr 0.17   ψ ,
d′i   µw   Al′ hr ft 2 oF

= _______________ ________________ _______________
(e) If 2000 < Re < 10,000 = _______________ ________________ _______________
Btu
(1) ( h′io )turb @ Re = 10,000 [from (b)],
hr ft 2 oF
= _______________ ________________ _______________
Btu
(2) ( h′io )iam @ Re = 2,000 [from (d)],
hr ft 2 oF
= _______________ ________________ _______________
(3) η = 1.25 – Re/8000 = _______________ ________________ _______________
Btu
(4) h′io = η (h′io )iam + (1 − η) (hio
′ ) turb ,
hr ft 2 oF
= _______________ ________________ _______________
′ + rio′ ) (TSb – TTb), °F
(f) Tw = TTb + Uo ( R io
= _______________ ________________ _______________
(g) Evaluate (µb / µw)0.14 for laminar flow
or φP for turbulent flow and make
necessary corrections to heat transfer = _______________ ________________ _______________
coefficients
m. Pressure Drop
(1) Nozzle Pressure Drop,
0.051 W = __________6.48__ ________________ _______________
(a) Vn = , ft/s
(DTNI) (DTNO ) ρ

ρ Vn2 = __________0.504_ ________________ _______________

(b) ∆Pn = , psi
5152
(2) Entrance, Expansion, and Turn-around
(a) From Table 4 in IX-D determine Ke = __________3.2___ ________________ _______________

EXXON RESEARCH AND ENGINEERING COMPANY - FLORHAM PARK, N.J.

 HEAT EXCHANGE EQUIPMENT DESIGN PRACTICES
CALCULATION PROCEDURE, Section Page
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ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-2 (Cont)

EXAMPLE PROBLEM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
Ke ρ Vt2
(b) ∆Pe = = __________0.896_ ________________ _______________
9274
(3) Frictional Pressure Drop
(a) From Figure 1.8 in IX-D, (December = __________0.0068 ________________ _______________
1995) evaluate fis
(b) From Figure 1.9 in IX-D, (December = __________0.99__ ________________ _______________
1995) evaluate φ
(c) From Figure 1.10 in IX-D, (December = __NOT REQ'D.____ ________________ _______________
1995) evaluate ψp
(d) f = fis φ ψp = __________0.00673 ________________ _______________
2
5.19 [ ρ ( Vt ) (NTP) L ]
(e) ∆Pt = f , psi = __________4.84__ ________________ _______________
10 3 d′i
(4) (∆Pt)nn = Ns [∆Pn + ∆Pe + (Ft) (∆Pt)], psi = __________8.8___ ________________ _______________
get value of Ft from Table 4 in IX-D,
(December 1995)
9. Iteration, Shell Side
Tube row spacing factor
a = 1.0 for Square Pitch
a = 0.867 for all others = __________0.867_ ________________ _______________
DEQ = dr + [DOF – dr] N′f (t ′f ) , in. = __________0.666_ ________________ _______________

Pitch Ratio (PR) = PT/DEQ = __________1.4077 ________________ _______________

Baffle Space to Bundle Diameter ratio (n)
n = LBCC / DOTL = __________1.12__ ________________ _______________
Shell side flow factor (m)
m = 0.5 for J shell
m = 2.0 for F shell
m = 1.0 for E shell = __________0.5___
Baffle flow factor (p)
p = 1.0 for segmental baffles
p = 0.5 for double-segmental baffles = __________1.0___ ________________ _______________
Baffle Correction factor (ξ)
ξ = 1.0 for segmental baffles
ξ = 0.8 for double-segmental baffles = __________1.0___ ________________ _______________
Estimated tube wall temperature (Tw), °F
Tw = TSb – 0.3 (TSb – TTb) = ________145.6___ ________________ _______________
Wall viscosity correction (φ)
0.14
µ 
φ =  b 

= __________1.0___ ________________ _______________
 µw 

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
Section Page CALCULATION PROCEDURE,
IX-G 46 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
December, 1999 PROPRIETARY INFORMATION - For Authorized Company Use Only

APPENDIX A-2 (Cont)

EXAMPLE PROBLEM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
Total cross flow mass velocity ( G′xt ), lb/hr ft2

 PR   (m) (p)   Ws 
G′xt = 144    
 PR − 1  n   (DOTL )2  = _____70,817_____ ________________ _______________

Total flow Reynolds Number ( Re ′xt ),

(DEQ) (G′xt )
Re ′xt = = ____126,074_____ ________________ _______________
29 µ b
Nominal Crossflow fraction (FFBn) Figure 1.1 in IX-D, = __________0.683_ ________________ _______________
December 1995
Baffle Spacing Correction (SC) Figure 1.2 in IX-D, = __________1.3___ ________________ _______________
December 1995
Reynolds Number Correction (RC) Figure 1.3 in IX-D, = __________1.0___ ________________ _______________
December 1995
Cross flow fraction for pressure drop (FFBp)
FFBp = (FFBn) (SC) (RC) (Maximum = 1.0) = __________0.8879 ________________ _______________
Cross flow Reynolds Number for ∆P ( Re ′xp )

Re ′xp = (Re ′xt ) (FFBp) = ____111,941_____ ________________ _______________

Shell side friction factor (f) Figure 1.4 in IX-D = __________0.09__ ________________ _______________
Cross flow fraction for heat transfer (FFBh)
FFBh = FFBp + 0.125 (Maximum = 1.0) = __________1.0___ ________________ _______________
Cross flow Reynolds Number for heat transfer ( Re ′xh )

Re ′xh = (Re ′xt ) (FFBh) = ____126,074_____ ________________ _______________

Shell side heat transfer factor (j) Figure 1.4 in IX-D, = __________0.0035 ________________ _______________
December 1995
Obtain αfh from Figure 2 in IX-G, December 1995 = __________1.2___ ________________ _______________
Obtain β from Figure 5 of IX-G, December 1995 = __________0.9___ ________________ _______________
Shell side film coefficient ( h′o ) Btu/hr ft2 °F
−2 / 3 0.14
 c p µb   µb 
h′o = 0.415 cp ( G′xt ) (FFBh) (j)  


µ

 β α fh
 k   w 
= ________129.2___ ________________ _______________
Shell side Friction Term (HF′)
 12 ( f ) (L ) (m)   1 
HF′ = 0.00875     (Fs ) = __________0.0787 ________________ _______________
 (a )(PR)(DEQ)(n)   φ 
(Get value of Fs from Table 4 in IX-D, December 1995)
Shell side momentum term (HM)
 (12) (L ) (m) 
HM = 0.00168 (n)2.6  − 1 .0  = __________0.0124 ________________ _______________
 ( n ) (DOTL ) 
Obtain value of αfp from Figure 4 in IX-G
Shell side pressure drop without Nozzle (∆ P′s ), psi

EXXON RESEARCH AND ENGINEERING COMPANY - FLORHAM PARK, N.J.

 HEAT EXCHANGE EQUIPMENT DESIGN PRACTICES
CALCULATION PROCEDURE, Section Page
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ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-2 (Cont)

EXAMPLE PROBLEM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
2
(0.3) [HF′ + HM]  (G′xt ) (FFB p )   1
∆ P′s =
ρ
  ξ
( )
  α fp
=____________3.77_ ________________ _______________
 10,000   
Nominal shell nozzle I.D. (DN), in.
DN = (DSNI) (DSNO) = __________12.09_ ________________ _______________

Shell side nozzle pressure drop (∆Psn), psi

2
0.84  Ws 
= ___________0.49_ ________________ _______________
∆Psn =  2 
ρ  (1000 ) (DN) 
Total shell side pressure drop (∆Pexch), psi
∆Pexch = Ns [∆ P′s + ∆Psn] = ___________4.3__ ________________ _______________

Calculated Tube wall temp. (Tw), °F

 1.0 
Tw = TSb – U′o   (TS b − TTb ) = ________________ ________________ _______________
 h′o 
Calculate viscosity correction (φ)
0.14
µ  = ________________ ________________ _______________
φ =  b 
 µw 
Using calculated value of φ correct hs and ∆Ps
10. Overall calculations
Inside resistance referred to outside area ( R′io ), hr ft2 °F/Btu
1
′ =
R io = _________0.002801 ________________ _______________
′
hio
Outside resistance ( R′o ), hr ft2 °F/Btu

R ′o = 1/ h′o = __________0.00774 ________________ ______________

Obtain value of fin efficiency, Ew, from Figure 3 in

IX-G
Total clean resistance ( R′c ), hr ft2 °F/Btu = ________________ ________________ _______________

 R′ 
′ +  o
R ′c = R io  + rw′ = __________0.01146 ________________ _______________
 Ew 
Calculated overall fouled coefficient ( U′c ), Btu/hr ft2 °F
1
U′c = = __________87.3__ ________________ _______________
R ′c
Calculated overall clean coefficient ( U′D ), Btu/hr ft2 °F
1
′ =
UD
 R′  = __________46.9__ ________________ _______________
R ′io + rw′ + rio′ +  o  + ro′
 Ew 

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
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IX-G 48 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
December, 1999 PROPRIETARY INFORMATION - For Authorized Company Use Only

APPENDIX A-2 (Cont)

EXAMPLE PROBLEM (CUSTOMARY UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
Tubesheet thickness (TTT), ft
(C1) (DS + 2.5 ) (P / STT )0.5 + 1.0
TTT = = ___________0.28_ ________________ _______________
12.0
C1 = 0.625 for u-tubes, 1.0 for all others
P = higher of shell side or tube side design pressure
Effective tube length (Le), ft
Le = L – TTT = __________15.72_ ________________ ________________
Effective heat transfer area per shell (As), ft 2

As = (NTT) (Le) (AT) = _________814.5__ ________________ ________________

Total Effective heat transfer area (A), ft2
A = (As) (NT) = _________814.5__ ________________ ________________
Overall duty coefficient ( U′o ), Btu/hr ft2 °F
Q
U′o = __________46.1__ ________________ ________________
( A) (MTD )
U′D − U′o
% Overdesign = x 100 = __________+1.7__ ________________ ________________
U′o
(Normally required for Copper alloys)
Tubesheet Temperature, TM:
a. For coolers. (Cooling Water on tube side)
i) Clean conditions, °F
′
R io
TM = TDT + [TDS − TDT ] = _______________ ________________ ________________
R ′c
ii) Fouled conditions, °F
TM = TDT + U′o (R io
′ + rio′ ) (TDS – TDT) = _______________ ________________ ________________

iii) Controlling case, °F

Larger of the clean or fouled = _______________ ________________ ________________
b. For exchangers
i) Tube side fluid being cooled
TM = TDT – 0.1 (TDT – TDS) = _______________ ________________ ________________
ii) Shell side fluid being cooled
TM = TDT – 0.3 (TDS + TDT) = ______________ ________________ ________________

EXXON RESEARCH AND ENGINEERING COMPANY - FLORHAM PARK, N.J.

 HEAT EXCHANGE EQUIPMENT DESIGN PRACTICES
CALCULATION PROCEDURE, Section Page
EXXON LOW-FINNED TUBES IX-G 49 of 56
ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-2M
EXAMPLE PROBLEM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
PROCESS ______________ REFINERY AND LOCATION ______________ CALC. BY____________
EXCHANGER NO. E – 001_________ DATE ____________
1. Terminal Conditions and MTD
Fluid Being Cooled T1 = __87.8__, T2 = __58.3__, T1 – T2 = __29.5__, T1 − T2
R = =___1.93_
t 2 − t1
Fluid Being Heated t2 = __47.5__, t1 = __32.2__, t2 – t1 = __15.3__, t 2 − t1
j = =___0.275
T1 − t1
T1 – t2 = __40.3__, T2 – t1 = __26.1__, T1 – t1 = __55.6__
LMTD (T1 − t 2 ) − (T2 − t1) = __32.68_°C
=
(T − t2 )
ln 1
(T2 − t1)

Fn = ___0.92_ for ____1___ shells in series ____1___ shells in parallel

(Figure 2 in IX-D) ________ for ________ shells in series ________ shells in parallel
________ for ________ shells in series ________ shells in parallel
MTD = Fn (LMTD) = ( 0.92 ) ( 32.68 ) = _30.07___°C
= ( ) ( ) = ________°C
2. Bulk Temperatures
Tube side (Heated) TTin = __32.2__, TTout = ___47.5°C
Fluid (Cooled)
TTin + TTout = ___39.85°C
TTb =
2
Shell side (Heated) TSin = __87.8__, TSout = ___58.3_°C
Fluid (Cooled)
TSin + TSout = ___73.05°C
TSb =
2

Estimated wall temperature Tw = TTb + 0.6 (TSb – TTb) ___59.78°C

3. Properties of Fluids
Tubes Shell
ρ = ______990.59______ kg/m3 ________5.73______ kg/m3
µb = ________0.000665__ Pa•s ________0.0000129_ Pa•s
cp = ________4.177_____ kJ/kg °C ________2.392_____ kJ/kg °C
k = ________0.634_____ W/m °C ________0.0415____ W/m °C
µw = ________0.000610__ Pa•s ________0.0000126_ Pa•s
4. Flow Rates and Name of Fluids
Tubes Shell
Fluid
Name / Phase = __WATER___/__LIQUID__
__METHANE_/__VAPOR__
Total Mass Rate _______9.324______ Kg/s _______8.442______ Kg/s
W = Total mass rate/Np = _______9.324______ Kg/s Ws = Total mass rate/NP = _______8.442______ Kg/s

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
Section Page CALCULATION PROCEDURE,
IX-G 50 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
December, 1999 PROPRIETARY INFORMATION - For Authorized Company Use Only

APPENDIX A-2M (Cont)

EXAMPLE PROBLEM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
5. Fouling Factors
ri = ________0.000352__ m2 °C/W
ro = ________0.000176__ m2 °C/W
6. Mechanical Design Features
TEMA Type: AJL Tubes Shell
Design Temperature = _____148.9________ °C _____148.9_______ °C
Design Pressure = ____2069__________ kPa ____2069_________ kPa
Nozzle Size DTNI = ______77.93_______ mm DSNI = _____307.09______ mm
DTNO = ______77.93_______ mm DSNO = _____307.09______ mm
7. Exchanger Geometry
First Trial Second Trial Third Trial
Tube O.D. (DO), mm = ______19.05_____ ________________ ______________
Tube I.D. ( d′i ), mm = ______11.658____ ________________ ______________

Tube pitch (PT), mm = ______23.8125___ ________________ ______________

d − d′i
Tube wall thickness (l) mm = r = _______2.134____ ________________ ______________
2
Tube length (L), m = _______4.877____ ________________ ______________
Tube flow length (LI), mm = ____4877_______ ________________ ______________
LI = (24) L for U tubes
LI = (12) L for all others
TEMA exchanger type = _____AJL_______ ________________ ______________
Single tube area/length AT, m2/m = _______0.155____ ________________ ______________
AT = AO′ from (Table 1M) in IX-G
Baffle spacing (LBCC), mm = _____398.2______ ________________ ______________
Tube length between baffle (L′), m = _______0.398____ ________________ ______________
Baffle type (Segmental or Double Segmental) = _____SEG_______ ________________ ______________
Shell inside diameter (DS), mm = _____387.4______ ________________ ______________
Bundle diameter (DOTL), mm = _____355.6______ ________________ ______________
Number of tube side passes (NTP) = _______2_______ ________________ ______________
(for U tubes minimum number is 2)
8. Iteration, Tube Side
a. Heat duty = Q, MW = _______0.59472__ ________________ ______________
b. Assumed value of U′o , W/m2 °C = _____259.3______ ________________ ______________

c. A = Q/ U′o (MTD), m2 = ______76.0______ ________________ ______________

d. As = A/NT, m2 = ______76.0______ ________________ ______________

e. Tube metal = __CS_, kw = 52.06, DOF = 18.82 mm, d′i = 11.658 mm, l ′ = 0.001448 m, L = 4.877 m, l = 2.134 mm
f. Tube pitch (PT) and Layout = _(23.8125) 30° ∆__ ________________ ______________
W
g. rio′ = (AO′ / Al′) ri , = _______0.001563_ ________________ ______________
2 o
m C
l [dr + 2 N′f (12 l ′ ) (dr + 12 l ′ ) W
h. rw′ = ,
12 k w (d r − l) 2 o
m C
= _______0.000159_ ________________ ______________

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 HEAT EXCHANGE EQUIPMENT DESIGN PRACTICES
CALCULATION PROCEDURE, Section Page
EXXON LOW-FINNED TUBES IX-G 51 of 56
ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-2M (Cont)

EXAMPLE PROBLEM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
i. NTT′ = _____102_______ ________________ _______________
j. N = NTT/NTP = ______51_______ ________________ _______________
6
W (1.273 x 10 = _______1.73_____ ________________ _______________
k. Vt = , m/s
ρ N (di′ ) 2
l. Heat Transfer Coefficient
1273 W ρ Vt (di′ ) (10 −3 ) = __30,050________ ________________ _______________
(1) Re ′ = =
µ b (di′ ) N µb
(2) For Water

0.26
(1.27 x 10 4 ) ( Vt ) 0.7  1.8 TTb + 32  W
h′io =   ,
 AO′   100  m oC
2
(d′i ) 0.3  
 Al′ 
= ___2028.6_______ ________________ _______________
(3) Fluids other than water = _______________ ________________ _______________
c p µb
(a) Pr = (103 ) = _______________ ________________ _______________
k
(b) If Re ≥ 10,000 = _______________ ________________ _______________
22 k 0.8 0.4 p  AO′  , W
′ =
hio R e Pr φ /   = _______________ ________________ _______________
d′i  Al′  m2 oC
φP = (µb/µw)0.167 for liquids = _______________ ________________ _______________
0.5
 TT + 273 
=  b  for heating gases = _______________ ________________ _______________
 Tw + 273 
 
= 1.0 for cooling gases = _______________ ________________ _______________
(c) If Re < 10,000 = _______________ ________________ _______________
(1) ∆T = Tw – TTb, °C = _______________ ________________ _______________
1 1
−
ρx ρy
(2) β′ = = _______________ ________________ _______________
 1 
(t x − t y )  

 ρ av 
 (d′ ) 3 ρ 2 β′ ∆T 
(3) Gr = (9.82 x 10-9)  i  = _______________ ________________ _______________
 (µ b ) 2 

(d) If Re ≤ 2000 = _______________ ________________ _______________

(1) From Figure 1.5 in IX-D = _______________ ________________ _______________
determine λ✶
(2) From Figure 1.6 in IX-D = _______________ ________________ _______________
determine ε

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
Section Page CALCULATION PROCEDURE,
IX-G 52 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
December, 1999 PROPRIETARY INFORMATION - For Authorized Company Use Only

APPENDIX A-2M (Cont)

EXAMPLE PROBLEM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
(3) λ = d′i / Ll + ε = _______________ ________________ _______________

(4) From Figure 1.7 in IX-D = ______________ ________________ _______________

determine ϕ
 0.14 
10 3 k   µb   AO′ W
2.5 + 4.5 [(R e + λ *)λ ]
0.37
(5) ′ =
hio = hio Pr0.17   ϕ/ ,
di′   µw   Al′ 2 o
m C

= ______________ ________________ _______________

(e) If 2000 < 10,000 = _______________ ________________ _______________
W
(1) ( h′io )turb @ Re = 10,000 [from (b)],
m oC2

= _______________ ________________ _______________

W
(2) ( h′io )iam @ Re = 2,000 [from (d)],
m oC
2

= _______________ ________________ _______________

(3) η = 1.25 – Re/8000 = _______________ ________________ _______________
W
(4) h′io = η (h′io )iam + (1 − η) (hio
′ ) turb ,
m oC
2

= _______________ ________________ _______________

′ + rio′ ) (TSb – TTb), °C
(f) Tw = TTb + Uo ( R io
= _______________ ________________ _______________
(g) Evaluate (µb / µw)0.14 for laminar flow
or φP for turbulent flow and make
necessary corrections to heat transfer = _______________ ________________ _______________
coefficients
m. Pressure Drop
(1) Nozzle Pressure Drop,
1.273 W x 106
(a) Vn = , m/s = ______1.973_____ ________________ _______________
(DTNI) (DTNO ) ρ

ρ Vn2 = ______3.468_____ ________________ _______________

(b) ∆Pn = , kPa
1112
(2) Entrance, Expansion, and Turn-around
(a) From Table 3 in IX-D determine Ke = ______3.2_______ ________________ _______________
Ke ρ Vt2
(b) ∆Pe = , kPa = ______6.17______ ________________ _______________
2000
(3) Frictional Pressure Drop
(a) From Figure 1.8 in IX-D evaluate fis = ______0.0068____ ________________ _______________
(b) From Figure 1.9 in IX-D evaluate φ = ______0.99______ ________________ _______________
(c) From Figure 1.10 in IX-D evaluate ψp = __NOT REQ'D.___ ________________ _______________
(d) f = fis ϕ ψp = ______0.00673___ ________________ _______________

EXXON RESEARCH AND ENGINEERING COMPANY - FLORHAM PARK, N.J.

 HEAT EXCHANGE EQUIPMENT DESIGN PRACTICES
CALCULATION PROCEDURE, Section Page
EXXON LOW-FINNED TUBES IX-G 53 of 56
ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-2M (Cont)

EXAMPLE PROBLEM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
2
[ ρ ( Vt ) (NTP) L ]
(e) ∆Pt = 2 f , kPa = _____33.39_____ ________________ _______________
d′i
(4) (∆Pt)nn = Ns [∆Pn + ∆Pe + (Ft) (∆Pt)], kPa = _____60.73_____ ________________ _______________
get value of Ft from Table 3 in IX-D
9. Iteration, Shell Side
Tube row spacing factor
a = 1.0 for Square Pitch
a = 0.867 for all others = ______0.867____ ________________ _______________
DEQ = dr + [DOF – dr] N′f ( t ′f ), mm = _____16.916____ ________________ _______________

Pitch Ratio (PR) = PT/DEQ = ______1.4077___ ________________ _______________

Baff. Space to Bundle Dia ratio (n)
n = LBCC / DOTL = ______1.2______ ________________ _______________
Shell side flow factor (m)
m = 0.5 for J shell
m = 2.0 for F shell
m = 1.0 for E shell = ______0.5______ ________________ _______________
Baffle flow factor (p)
p = 1.0 for segmental baffles
p = 0.5 for double-segmental baffles = ______1.0______ ________________ _______________
Baffle Correction factor (ξ)
ξ = 1.0 for segmental baffles
ξ = 0.8 for double-segmental baffles = ______1.0______ ________________ _______________
Estimated tube wall temperature (Tw), °C
Tw = TSb – 0.3 (TSb – TTb) = _____63.09_____ ________________ _______________
Wall viscosity correction (φ)
0.14
µ 
φ =  b  = ______1.0______ ________________ _______________
 µw 
Total cross flow mass velocity ( G′xt ), kg/s m2

 PR   (m) (p)   Ws 
G′xt = 106    
2
 PR − 1  n   (DOTL)  = _____96.1______ ________________ _______________

Total flow Reynolds Number ( R′ext ),

(DEQ) (G′xt ) (10 −3 )

R ′ext = = ___126,020_____ ________________ _______________
µb
Nominal Crossflow fraction (FFBn) Figure 1.1 in IX-D = ______0.683____ ________________ _______________
Baffle Spacing Correction (SC) Figure 1.2 in IX-D = ______1.3______ ________________ _______________
Reynolds Number Correction (RC) Figure 1.3 in IX-D = ______1.0______ ________________ _______________
Cross flow fraction for pressure drop (FFBp)
FFBp = (FFBn) (SC) (RC) (Maximum = 1.0) = ______0.8879___ ________________ _______________
Cross flow Reynolds Number for ∆P ( R′exp )

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
Section Page CALCULATION PROCEDURE,
IX-G 54 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
December, 1999 PROPRIETARY INFORMATION - For Authorized Company Use Only

APPENDIX A-2M (Cont)

EXAMPLE PROBLEM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
R ′exp = (R ′ext ) (FFBp) = ___111,893_____ ________________ _______________

Shell side friction factor (F) Figure 1.4 in IX-D = ______0.09_____ ________________ _______________
Cross flow fraction for heat transfer (FFBh)
FFBh = FFBp + 0.125 (Maximum = 1.0) = ______1.0______ ________________ _______________
Cross flow Reynolds Number for heat transfer ( R′exh )

R ′exh = (R ′ext ) (FFBh) = ___126,020_____ ________________ _______________

Shell side heat transfer factor (f) Figure 1.4 in IX-D = ______0.0035___ ________________ _______________
Obtain αfh from Figure 2 in IX-G = ______1.2______ ________________ _______________
Obtain β from Figure 5 in IX-G = ______0.9______ ________________ _______________
Shell side film coefficient ( h′s ) W/m2 °C
−2 / 3 0.14
 c p µb   µb 
h′s = 7.5 cp ( G′xt ) (FFBh) (j)  


µ

 β α fh
 k   w 
= ____705.1______ ________________ _______________
Shell side Friction Term (HF′)
 1000 ( f ) (L ) (m)   1 
HF′ = 0.00875     (Fs ) = ______0.0787___ ________________ _______________
 (a )(PR)(DEQ)(n)   φ 
(Get value of Fs from Table 3 in IX-D)
Shell side momentum term (HM)
 (1000 ) (L ) (m) 
HM = 0.00168 (n)2.6  − 1. 0  = ______0.0124___ ________________ _______________
 (n) (DOTL ) 
Obtain value of αfp from Figure 4 in IX-G
Shell side pressure drop without Nozzle (∆Ps), kPa
2
(0.3) [HF′ + HM]  (G′xt ) (FFB p ) 
∆ P′s =
ρ
 
 1
( )
  α fp = _____26.0______ ________________ _______________
 10,000  ε
Nominal shell nozzle I.D. (DN), mm
DN = (DSNI) (DSNO) = ____307.09_____ ________________ _______________

Shell side nozzle pressure drop (∆Psn), kPa

2
24.31  Ws (10 4 ) 
∆Psn =   = ______3.4______ ________________ _______________
ρ 2
 (DN) 
Total shell side pressure drop (∆Pexch), kPa
∆Pexch = Ns [∆ P′s + ∆Psn] = _____29.4______ ________________ _______________

Calculated Tube wall temp. (Tw), °C

 1.0 
Tw = TSb – U′o   (TS b − TTb ) = _______________ ________________ _______________
 h ′s 

EXXON RESEARCH AND ENGINEERING COMPANY - FLORHAM PARK, N.J.

 HEAT EXCHANGE EQUIPMENT DESIGN PRACTICES
CALCULATION PROCEDURE, Section Page
EXXON LOW-FINNED TUBES IX-G 55 of 56
ENGINEERING Date
PROPRIETARY INFORMATION - For Authorized Company Use Only December, 1999

APPENDIX A-2M (Cont)

EXAMPLE PROBLEM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
Calculate viscosity correction (φ)
0.14
µ  = _______________ ________________ _______________
φ =  b 

 µw 
Using calculated value of φ correct hs and ∆Ps
10. Overall calculations
Inside resistance referred to outside area (R′io), hr m2 °C/W
1
R ′io = = ______0.000493_ ________________ _______________
′
hio
Outside resistance ( R′o ), m2 °C/W

R ′o = 1/ h′s = ______0.001418_ ________________ _______________

Obtain value of fin efficiency, Ew, from Figure 3M in = _______________ ________________ _______________
IX-G
Total clean resistance ( R′c ), m2 °C/W

 R′ 
R ′c = R ′io +  o  + rw′ = ______0.00216_ ________________ _______________
 Ew 
Calculated overall clean coefficient ( U′c ), W/m2 °C
1
U′c = = ____462.9______ ________________ _______________
R ′c

Calculated overall clean coefficient ( U′D ), W/m2 °C

1
′ =
UD
 R′  = ____256.4______ ________________ _______________
R ′io + rw′ + rio′ +  o  + ro′
 Ew 
Tubesheet thickness (TTT), ft
(C1) (DS + 64 ) (P / STT )0.5 + 25.0
TTT = = ______0.084____ ________________ _______________
1000
C1 = 0.625 for u-tubes, 1.0 for all others
P = higher of shell side or tube side design pressure
Effective tube length (Le), m
Le = L – TTT = ______4.793____ ________________ _______________
Effective heat transfer area per shell (As), ft2
As = (NTT) (Le) (AT) = _____75.78_____ ________________ _______________
Total Effective heat transfer area (As), m2
A = (As) (NT) = _____75.78_____ ________________ _______________
Overall duty coefficient (Uo), w/m2 °C
Q
U′o = = ____260.99_____ ________________ _______________
( A) (MTD )
U′D − U′o
% Overdesign = x 100 = _____- 1.76_____ ________________ _______________
U′o
(Normally required for Copper alloys)

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 DESIGN PRACTICES HEAT EXCHANGE EQUIPMENT
Section Page CALCULATION PROCEDURE,
IX-G 56 of 56 LOW-FINNED TUBES EXXON
Date ENGINEERING
December, 1999 PROPRIETARY INFORMATION - For Authorized Company Use Only

APPENDIX A-2M (Cont)

EXAMPLE PROBLEM (METRIC UNITS)
SHELL AND TUBE HEAT EXCHANGERS (NO CHANGE OF PHASE)
First Trial Second Trial Third Trial
Tubesheet Temperature, TM:
a. For coolers. (Cooling Water on tube side)
i) Clean conditions, °C
′
R io
TM = TDT + [TDS − TDT ] = _______________ ________________ _______________
R ′c
ii) Fouled conditions, °C
′ + rio′ ) (TDS – TDT)
TM = TDT + Uo ( R io = _______________ ________________ _______________

iii) Controlling case, °C

Larger of the clean or fouled = _______________ ________________ _______________
b. For exchangers
i) Tube side fluid being cooled
TM = TDT – 0.1 (TDT – TDS) = _______________ ________________ _______________
ii) Shell side fluid being cooled
TM = TDT + 0.3 (TDS – TDT) = _______________ ________________ _______________

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