A Report on “Study of Heat Transfer Coefficient in a Double Pipe What

Exchanger”

Samiha Raisa Alam

1802028
Level-3 Term-2
Dept. of Chemical Engineering
Bangladesh University of Engineering and Technology

Date of Performance: 19.12.2022

Date of Submission: 09.01.2023

Group: 06 (1802026, 1802027, 1802028, 1802029, 1802030)

Submitted to:
Athkia Fariha
Lecturer
Dept of Chemical Engineering
Bangladesh University of Engineering and Technology
Summary:
Experimental Setup

 Apparatus
1. Double Pipe Heat Exchanger
2. Boiler (for supply of saturated steam)
3. Steam trap
4. Flow meter (for flow rate measurement of inlet water)
5. Pressure gauge
6. Thermometer
7. Bucket and stopwatch (for flow rate measurement of condensate)

 Experimental Procedure
The double pipe heat exchanger and all other equipment are arranged according to the
schematic diagram. The experiment is begun by passing water through the inlet pipe and
the flowrate is observed and noted from the flow meter. the saturated steam is also
allowed to pass through the annulus and the pressure is adjusted at 5 psig, 10 psig and 15
psig respectively. The pressure valve is used to minimize deviation of the pressure from
the desired one. The necessary data (inlet and outlet temperatures, pressure, condensate
flowrate etc.) are observed and noted. The temperatures are obtained from the
thermometers placed within the tube, and pressure is read from the pressure gauge. Flow
rate of condensate is determined by collecting a portion of it in a bucket and recording the
time with a stopwatch. At a specific pressure, the flow rate of water is changed to obtain
different sets of readings.
  Schematic Diagram of Experimental Setup

Figure 1: Schematic Diagram for the Experimental Setup for the Study of Double Pipe Heat Exchanger.
Results and Discussion

 Observed Data

Pipe length= 7 ft 4 inch

Nominal diameter =1inch
Schedule no = 40

Table 1: Observed Data for the steam pressure, water temperature, water flowrate and the condensate
flowrate

Water Temperature (℃) Steam Flow Rate

Steam
No. of Water Flow
Pressure
Observation Inlet Outlet Rate (L/s) Condensate Time
(psig)
Temp Temp Weight (kg) (s)

1 24.5 45.0 0.19 0.910 120

2 24.5 40.0 0.50 1.420 120

5
3 24.5 34.0 0.63 1.319 120

4 24.5 33.0 0.64 1.443 120

1 24.5 38.0 0.38 1.167 120

2 24.5 37.0 0.48 1.279 120

10
3 24.5 35.0 0.57 1.361 120

4 24.5 34.5 0.61 1.291 120

1 24.5 39.0 0.39 1.351 120

2 24.5 37.0 0.51 1.364 120

15
3 24.5 35.5 0.60 1.389 120

4 24.5 35.0 0.61 1.480 120

  Calculated Data

Table 2: Physical Properties of Water at Average Temperature.

Steam Obs. Temperature Average Specific Density Viscosity Thermal

Pressure, No. difference Water Heat , ρ (kgm- , µ(Pa.s) conductivity,
P between temperature, Capacity, 3) ×10-4 km(Wm-1K-1)
(psig) outlet and Tm(℃) Cpm
inlet, ∆T (Jkg-1K-1)
(℃)

1 20.5 34.75 4179 993.9 7.25 0.625

2 15.5 32.25 4179 994.8 7.65 0.622

5
3 9.5 29.25 4179 995.5 8.11 0.618

4 8.5 28.75 4179 995.8 8.21 0.615

5 13.5 31.25 4179 995.1 7.79 0.62

6 12.5 30.75 4179 995.3 7.87 0.619

10
7 10.5 29.75 4179 995.5 8.02 0.618

8 10.0 29.50 4179 995.5 8.08 0.62

9 14.5 31.75 4179 995.0 7.73 0.619

10 12.5 30.75 4179 995.3 7.87 0.618

15
11 11.0 30.00 4179 995.4 7.98 0.618

12 10.5 29.75 4179 995.5 8.02 0.618

Table 3: Calculated Data for The Saturation Temperature Of Steam, Heat Of Condensation, Mass
Flowrate Of Water, Mass Flowrate Of Condensate, Heat Given Up By Steam, Heat Taken Up By Water.

Steam Obs Steam Heat of Mass Mass Rate of Rate of

Pressure, No. Saturation Condensation, flowrate flowrate of Heat Heat taken
P temperature, λ (kJ/kg) of water, condensate, given up up by
(psig) Ts (℃) Mw(kg/s) Mc(kg/s) by water,
steam ,Qc Qw (W)
(W)

5 1 108.37 2234.3 0.18884 0.00758 16943.44 16177.91

2 108.37 2234.3 0.49695 0.01183 26439.22 32189.69

3 108.37 2234.3 0.62616 0.01099 24558.68 24858.75

4 108.37 2234.3 0.63610 0.01203 26867.46 22595.08

10 1 115.25 2215.5 0.37768 0.00973 21545.74 21307.50

2 115.25 2215.5 0.47707 0.01066 23613.54 24921.05

3 115.25 2215.5 0.56652 0.01134 25127.46 24858.75

4 115.25 2215.5 0.60628 0.01076 23835.09 25336.40

15 1 120.93 2199.5 0.38762 0.01126 24762.70 23488.09

2 120.93 2199.5 0.50689 0.01137 25000.98 26478.61

3 120.93 2199.5 0.59634 0.01158 25459.21 27413.15

4 120.93 2199.5 0.60628 0.01233 27127.17 26603.22

Table 4: Calculated Data for Mean Heat Rate, LMTD, Experimental Overall Heat Transfer Co-Efficient,
Velocity Of Water And The Reynolds Number.

Steam Obs Mean LMTD, Experimental Wall Velocity Reynolds

Pressure,P . No. heat ∆Tlm(℃) Overall heat temperature, of water, Number,
(psig) rate ,Qm transfer co- Tw (℃) v (ms-1) Re
(W) efficient, UOE
(W/m2.K)

5 1 16560.68 73.14 961.85 71.56 0.339286 12558.39

2 29314.45 75.86 1641.66 70.31 0.892049 31320.38

3 24708.71 79.02 1328.25 68.81 1.123192 37225.29

4 24731.27 79.54 1320.78 68.56 1.140677 37355.56

10 1 21426.62 83.82 1085.94 73.25 0.677753 23375.70

2 24267.29 84.35 1222.23 73.00 0.855937 29227.05

3 24993.10 85.39 1243.35 72.50 1.016221 34057.98

4 24585.74 85.65 1219.37 72.38 1.087535 36177.36

15 1 24125.40 88.98 1151.75 76.34 0.695659 24177.06

2 25739.80 90.04 1214.47 75.84 0.909433 31053.74

3 26436.18 90.82 1236.56 75.47 1.069814 36030.21

4 26865.19 91.08 1253.04 75.34 1.087535 36448.02

Table 5: Calculated Data For Prandtl Number, Water Side Heat Transfer Co-Efficient, Nusselt Number,
Film Temperature, Density At Film Temperature, Viscosity At Film Temperature, Thermal Conductivity
At Film Temperature.

Steam Obs. Prandtl Water Nusselt Film Density of Viscosit Thermal

pressure No. Number side heat Number temperature water at, y of Conductivity
,P , transfer , , Tf, ρ f ¿ Water of water at, kf
(psig) Pr co- (Nu) Tf (℃) kg/m3) at, µf (W/m.K)
efficient , ×10-4
hi (Pa.s)
(W/m2.K
)

5 1 4.85 1713.57 74.03 80.76 971.2 3.49 0.670

2 5.14 3612.41 156.81 79.83 971.6 3.54 0.670

3 5.48 4211.06 183.98 78.70 971.9 3.59 0.670

4 5.58 4226.40 185.55 78.51 972.0 3.60 0.670

10 1 5.25 2869.72 124.97 83.75 968.8 3.36 0.672

2 5.31 3439.28 150.02 83.56 968.9 3.36 0.672

3 5.42 3907.33 170.71 83.19 969.0 3.37 0.672

4 5.45 4119.74 179.41 83.09 969.0 3.37 0.672

15 1 5.22 2937.41 128.13 87.49 966.7 3.23 0.674

2 5.32 3606.31 157.56 87.11 966.8 3.24 0.674

3 5.40 4080.51 178.27 86.83 967.1 3.25 0.674

4 5.42 4125.19 180.23 86.74 967.1 3.25 0.674

Table 6 :Calculated data for the steam side heat transfer co-efficient, Theoretical overall heat transfer
co-efficient, reciprocal of the experimental overall heat transfer co-efficient, reciprocal of the theoretical
heat transfer co-efficient.

Steam Obs Steam Theoretical Experimental Theoretical (1/v)0.8

pressure No. side heat overall heat 1/UOE 1/UOT (m2.K/W) (s/m)
(psig) transfer transfer co- (m2.K/W)
co- efficient UOT
efficient (W/m2.K)
ho
(W/m2.K)

1 7978.56 1080.41 0.001040 0.000926 2.3744

2 7885.77 1811.18 0.000609 0.000552 1.0957

5
3 7783.79 1977.50 0.000753 0.000506 0.9112

4 7766.54 1980.50 0.000757 0.000505 0.9001

1 7784.69 1559.24 0.000921 0.000641 1.3650

2 7773.55 1751.35 0.000818 0.000571 1.1325

10
3 7745.37 1890.76 0.000804 0.000529 0.9872

4 7739.72 1949.87 0.000820 0.000513 0.9351

1 7739.96 1581.62 0.000868 0.000632 1.3369

2 7712.85 1800.04 0.000823 0.000556 1.0789

15
3 7692.16 1936.09 0.000809 0.000517 0.9474

4 7686.88 1947.99 0.000798 0.000513 0.9351

 Graphical Representation
The Nusselt number versus Reynolds number for each pressure was plotted on a log-log plot.
This revealed a linear relationship in logarithmic scale such that Nusselt number increased with
increasing Reynolds number.

Nu vs Re (5 psig)

f(x) = 0.00447257968363738 x + 17.6355725825026

R² = 0.999805590794122
Nu

60.00
10000
Re

Figure 2: Log-Log Plot of Nusselt Number vs Reynolds Number for a Steam Pressure of 5 psig.

Nu vs Re (10 psig)

f(x) = 0.0042605494955705 x + 25.4369791745126

R² = 0.999965205636032
Nu

100.00
20000.00
Re

Figure 3: Log-Log Plot Of Nusselt Number Vs Reynolds Number For A Steam Pressure Of 10 psig.
 Nu vs Re (15 psig)

f(x) = 0.0042363344503343 x + 25.7917778371159

R² = 0.999956459999853
Nu

100.00
20000
Re

Figure 4: Log-Log Plot of Nusselt Number vs Reynolds Number for a Steam Pressure of 15 psig.

The Dittus-Boelter equation was applied to determine the Nusselt number from the
corresponding Reynolds numbers and Prandtl numbers [Nu=0.023× (Re) 0.8×(Pr)1/3]. Both
dimensionless numbers used in the equation had varied for each observation. As a result, the
Nusselt numbers varied accordingly. The plots of the Nusselt number versus Reynolds number
show that for each pressure, the Dittus-Boelter equation provided a similar estimation. The
 hi vs v (5 psig)
10000.00

f(x) = 3166.26537352762 x + 674.173132700953

R² = 0.995720340730566
hi

1000.00
0.2 2
Velocity, v

Figure 3: Waterside Heat Transfer Co-Efficient Hi Vs Velocity Of Water In Tube (V) For A Steam
Pressure Of 5 Psig.

hi vs v (10 psig)

f(x) = 3041.98762273191 x + 817.752459545715

R² = 0.999508238433272
hi

2000.00
0.5
Velocity, v

Figure 6: Waterside Heat Transfer Co-Efficient H i Vs Velocity Of Water In Tube (V) For A Steam
Pressure Of 10 Psig.
 hi vs v (15 psig)

f(x) = 3036.19611457191 x + 831.480432906935

R² = 0.999679890071346
hi

2000.00
0.5
Velocity, v

Figure 7: Waterside Heat Transfer Co-Efficient H i Vs Velocity Of Water In Tube (V) For A Steam
Pressure Of 15 Psig.

Experimental Linear (Experimental)

Theoretical Linear (Theoretical)
0.001100

0.001000

0.000900

0.000800
1/U

0.000700

0.000600

0.000500

0.000400
0.5000 0.7000 0.9000 1.1000 1.3000 1.5000 1.7000 1.9000 2.1000 2.3000 2.5000
(1/v)^0.8

Figure 4: 1/U Vs (1/v)0.8 For A Steam Pressure Of 5 Psig.

 Experimental Linear (Experimental)
Theoretical Linear (Theoretical)
0.001000

0.000900

0.000800

0.000700
1/U

0.000600

0.000500

0.000400
0.8000 0.9000 1.0000 1.1000 1.2000 1.3000 1.4000
(1/v)^0.8

Figure 9: 1/U Vs (1/v)0.8 For A Steam Pressure Of 10 Psig.

Experimental Linear (Experimental)

Theoretical Linear (Theoretical)
0.000900

0.000850

0.000800

0.000750

0.000700

0.000650
1/U

0.000600

0.000550

0.000500

0.000450

0.000400
0.8000 0.9000 1.0000 1.1000 1.2000 1.3000 1.4000
(1/v)^0.8

Figure 10: 1/U Vs (1/v)0.8 For A Steam Pressure Of 15 Psig.

 Discussion
Safety Precautions:
Industrial Relevance
Appendix

 Sample Calculation:

For observation No. 03 (5 psig steam pressure),

Water inlet temperature, T1 = 24.5 oC
Water outlet temperature, T2 = 34 oC
(T 1+T 2) (24.5+34 ) o
Mean temperature of water, Tm = = C = 29.25 oC
2 2
Properties at mean temperature, Tm= 29.25oC :
Density of water, ρm = 995.50 kg/m3 [3]
Viscosity of water, μm = 8.11 x 10-4 Pa.s [3]
Thermal conductivity of water, km = 0.618 W/m.oC [3]
Specific heat of water, Cp= 4179 J/kg.K [3]

Volumetric flow rate of water, Ww =0.63 L/s

0.63 ×995.50
Mass flow rate of water, Mw = W w × ρm = ( ) kg/s = 0.62616 kg/s
1000

Mass of condensate collected Wc = 1.319 kg

Condensate collection time, tc = 120 s
Wc 1.319
Mass flow rate of condensate, MC = =( ) kg/s = 0.01099 kg/s
tc 120

Rate of heat taken by water, Qw = Mw × Cp× (T2-T1)

= 0.62616 × 4179.00 × (34-24.5) J/s
= 24858.75 W

Heat of condensation of steam at 5 psig (1.3578 bar), λs = 2234.3 kJ/kg [5]

Rate of heat given by steam, Qc = Mc × λs
= (0.01099 × 2234.3) kJ/s
= 24558.68 J/s
Mean rate of heat flow,
QW +QC 24558.68+24858.75
Qm = = J /s = 24708.71 J/s
2 2

Saturation temperature of steam at 5psig (1.3578 bar), Ts = 108.37 oC [5]

Temperature difference at inlet,

ΔT1 = Ts - T1 = (108.37 – 24.5) oC = 83.87 oC
Temperature difference at outlet,
ΔT2 = Ts - T2 = (108.37 – 34) oC = 74.37 oC
Log mean temperature difference,
ΔT 1 −ΔT 2
ΔT 1 83.87−74.37
ln 83.87
ΔT 2 ln
74.37
o
ΔTlm = = C = 79.02 oC

For 1 in. nominal diameter & schedule 40 steel tube,

The outside surface per linear feet, Ao = 0.344 ft2/ft. [1]
Inside diameter (ID) of the pipe, Di = 1.049 in. = 0.027 m. [1]
Outside diameter (OD) of the pipe, Do = 1.32 in. = 0.033 m. [1]
Tube length = 7 ft. 4 in. = 88 in. = 7.33 ft. [1]
Outside area available for heat transfer, Ao = 0.344×7.33 ft2 = 23.54 x 10-2 m2.

Qm
Experimental overall heat transfer coefficient, UOE = ΔT lm . A0
24708.71 2 o
= −2 W/m . C
79.02× 23.54 ×10
= 1328.25 W/m2.oC
Now,
 0.62616
Ww 1000
Velocity of water flow, v = = 2 m/s = 1.123 m/s
Ai 0.02665
3.1416 ×( )
4

Di × ρ× v 0.027 ×995.50×1.123
Reynolds number of water, Re = = (− 4) = 37225.29
μm 8.11×10

C P × μm 4179 ×8.11× 1 0−04

Prandtl no. of water, Pr = = = 5.48
km 0.618

1
Nusselt number of water, Nu=0.023 × ℜ0.8 × Pr 3 = 183.98

Water side heat transfer coefficient for turbulent flow using Dittus-Boelter equation,
km
hi = 0.023 × D i ×(Re)0.8 ×(Pr)1/3

0.618
= 0.023× × (37225.29)0.8× (5.48)1/3
0.027

= 4211.06 W/m2.oC

T s+T m 108.37+29.25
Wall temperature, Tw= = ℃=68.81 ℃
2 2

Film temperature, Tf = Ts - 0.75 × (Ts-Tw)

= 108.37 - 0.75× (108.37–68.81) oC
= 78.70 oC

Properties of condensate at film temperature, Tf = 78.70oC:

Density, ρf = 971.9 kg/m3 [3]

Viscosity of condensate, μf = 3.59 ×10−4 kg/m.s [3]

Thermal conductivity of condensate, kf = 0.67 W/m.oC [3]

Steam side heat transfer coefficient using Nusselt equation for film type condensation,
 k 3 . ρ 2 . g . λS
f f 0. 25
0 . 725×[ ]
ho = D 0 (T S −T W )μ f

=0.725 ׿ W/m2.oC
= 7783.79 W/m2.oC

Carbon-steel metal’s thermal conductivity, kM = 43 W/m.oC [3]

Theoretical overall heat transfer coefficient,

UOT = ¿
= ¿ W/m2.oC
= 1080.41 W/m2.oC

1 1
Now, = =¿ 0.000753 m2.oC/W
U OE 1328.25

1 1
= = 0.000506 m2.oC/W
U OT 1 977 .50

1 1
= 0.8
v
0.8 ¿ ¿ (s/m)
References
[1] Kern, D. Q. (1050). Process Heat Transfer, International Edition, Mcgraw-hill Book
Company.
[2] Franzini, J. B., Finnemore, E. J., & Daugherty, R. L. (1997). Fluid mechanics with
engineering applications. New York: McGraw-Hill.
[3] Holman, J. P., and Bhattacharyya, Souvik. Heat Transfer-In Si Units. Tata McGraw-Hill
Education, 2002.
[4] Foust, A. S., L. A. Wenzel, C. W. Clump, L. Maus, and Andersen, L. B. (1980).
Principles of Unit Operations, 2nd Edition., New York: John Wiley & Sons.
[5] Felder, R. M., & Rousseau, R. W. (1986). Elementary principles of chemical processes.
New York: Wiley.