Assignment

Submitted to:-

Mam Rabia Sabir

Submitted by:-

Fahad Kamran

Reg no:-
Uw-18-ChE-bSC-006

Chemical Engineering Department

WAH ENGINEERING COLLEGE

UNIVERSITY OF WAH
Q1:-
(a)
Features of shell and tube heat ex-changer according to TEMA Design:-
 TEMA requirements also serve to standardize exchanger thermal performance.
 The tubes may be permanently positioned inside the shell (fifixed tubesheet exchanger) or may be
removable for ease of cleaning and replacement (flfloating-head or U-tube exchanger).

(b)

SHELL ADVANTAGES DIS-ADVANTAGES DIAGRAM

TYPE
E Wide application for Reverse heat transfer possible
single-phase, boiling, and with even number
condensing services of tube passes and no fouling
Temperature crossa possible
without reverse heat transferb
with a single tube pass

F Temperature change for Longitudinal bafflfle can leak if

shell-side flflow streams can be not welded
higher than E-shell. Thermal conduction across
Fewer shells-in-series needed to longitudinal bafflfle
achieve multiple Removable bundles more costly to
shell passes maintain

G Suitable for horizontal shell-side Fewer tube-pass options with

reboilers removable bundle
Split flow Thermal conduction across
lowers entrance/exit velocities longitudinal bafflfle
Lowers vibration potential Temperature profifile not ideal as
Improved tube support under compared with
nozzle counter- or co-current flflow in
E-shell
H Suitable for horizontal shell-side More nozzles than G-shell
reboilers Thermal conduction across
Double split flflow lowers longitudinal bafflfle
entrance/exit velocities and Temperature profifile not ideal as
provides additional tube support compared with
compared to G-shell counter- or co-current flflow
(c)
Q2:-
(a) Gesketed Plate and Frame Heat Exchanger:-
The concept behind a heat exchanger is relatively simple – heating or cooling one medium by transferring
heat between it and another one.
In a gasketed plate heat exchanger, the plates are fitted with elastomeric gaskets which seal the channels and
direct the media into alternate channels. The plate pack is assembled between a frame plate and a pressure
plate, and compressed by tightening bolts fitted between these plates. The channel plates and the pressure
plate are suspended from an upper carrying bar and fixed in position by a lower guiding bar, both of which
are fixed to the support column. The design allows easy cleaning and simple capacity modification (by
removing or adding plates).

The heat transfer area of a gasketed plate heat exchanger consists of a series of corrugated plates, assembled
between a frame and pressure plates to retain pressure. Gaskets act as seals between the plates. Fluids
normally run counter-currently through the heat exchanger. This gives the most efficient thermal
performance and enables a very close temperature approach, ie the temperature difference between the
exiting process medium and the entering service medium.
For heat sensitive or viscous media, co-current flow can be used to let the coldest fluid meet the hottest
when entering the heat exchanger. This minimizes the risk of the media overheating or freezing.
Plates are available with various pressing depths, angles of chevron pattern and various corrugation shapes,
all carefully designed and selected to achieve optimal performance. Depending on the application, each
product range has its own specific plate features.
The distribution area ensures fluids are evenly distributed across the entire heat transfer surface and help
avoid stagnant zones that may cause fouling.
While high flow turbulence between plates results in higher heat transfer, the consequence is pressure drop.
Our thermal design engineers can help you design and select the model and configuration that is suitable for
your application so that it delivers maximum thermal performance with minimum pressure drop.

Gasketed plate heat exchangers for modern requirements:-

 Highest thermal efficiency and close temperature approach

 Compact units - space saving, easy to service and maintain

 Maximum uptime - less fouling, stress, wear and corrosion

 Flexible - easy to adapt to changed duty requirements

Advantages:-
Flexibility: Simple disassembly enables the adaptation of PHEs to new process requirements by simply
adding or removing plates, or rearranging the number of passes. Moreover, the variety of patterns of plate
corrugations available, together with the possibility of using combinations of them in the same PHE, means
that various conformations of the unit can be tested during optimization procedures.
Good temperature control: Due to the narrow channels formed between adjacent plates, only a small
volume of fluid is contained in a PHE. The device therefore responds rapidly to changes in process
conditions, with short lag times, so that the temperatures are readily controllable. This is important when
high temperatures must be avoided. Furthermore, the shape of the channels reduces the possibility of
stagnant zones (dead space) and areas of overheating.
Low manufacturing cost: As the plates are only pressed (or glued) together, rather than welded, PHE
production can be relatively inexpensive. Special materials may be used to manufacture the plates in order to
make them more resistant to corrosion and/or chemical reactions.
Efficient heat transfer: The corrugations of the plates and the small hydraulic diameter enhance the
formation of turbulent flow, so that high rates of heat transfer can be obtained for the fluids. Consequently,
up to 90% of the heat can be recovered, compared to only 50% in the case of shell-and-tube heat
exchangers.
Compactness: The high thermal effectiveness of PHEs means that they have a very small footprint. For the
same area of heat transfer, PHEs can often occupy 80% less floor space (sometimes 10 times less),
compared to shell-and-tube heat exchangers
(b) Shell and Plate Heat Exchanger:-
Shell-and-plate exchangers consist of a welded pack of circular plates that is, in turn, welded inside a
cylindrical shell. They combine the advantages of compact and thermally effificient plate technology with
ease of mechanical design and a fully welded cylindrical pressure vessel. This robust construction can
accommodate design pressures as high as 150 bar and temperatures up to 900 C. A number of different plate
materials are supported, including 304L and 316L stainless steels, duplex stainless steel, titanium and
Hastelloy . Specialized welding techniques make this technology possible, and companies capable of
performing this work arelimited. However, due to the mechanical advantages of these exchangers compared
to gasketed plate-frame units, their use in the process industries is expected to increase.
A PHE consists of a pack of thin rectangular plates with portholes, through which two fluid streams flow,
where heat transfer takes place. Other components are a frame plate (fixed plate), a pressure plate (movable
plate), upper and lower bars and screws for compressing the pack of plates (Figure 2). An individual plate
heat exchanger can hold up to 700 plates. When the package of plates is compressed, the holes in the corners
of the plates form continuous tunnels or manifolds through which fluids pass, traversing the plate pack and
exiting the equipment. The spaces between the thin heat exchanger plates form narrow channels that are
alternately traversed by hot and cold fluids, and provide little resistance to heat transfer.
Arrangement of a plate heat exchanger:-
The simplest types of arrangements of plate heat exchangers are those in which both fluids make just one
pass, so there is no change in direction of the streams. These are known as 1-1 single-pass arrangements, and
there are two types: countercurrent and concurrent. A great advantage of the single-pass arrangement is that
the fluid inlets and outlets can be installed in the fixed plate, making it easy to open the equipment for
maintenance and cleaning, without disturbing the pipework. This is the most widely used single-pass design,
known as the U-arrangement. There is also a single-pass Z-arrangement, where there is input and output of
fluids through both end plates
(c)Plate Fin Heat Exchanger:-
A plate-fin heat exchanger is a type of heat exchanger design that uses plates and finned chambers to
transfer heat between fluids. It is often categorized as a compact heat exchanger to emphasise its relatively
high heat transfer surface area to volume ratio. The plate-fin heat exchanger is widely used in many
industries, including the aerospace industry for its compact size and lightweight properties, as well as
in cryogenics where its ability to facilitate heat transfer with small temperature differences is utilized.

Aluminum alloy plate fin heat exchangers, often referred to as Brazed Aluminum Heat Exchangers, have
been used in the aircraft industry for more than 60 years and adopted into the cryogenic air separation
industry around the time of the second world war and shortly afterwards into cryogenic processes in
chemical plants such as Natural Gas Processing. They are also used in railway engines and motor
cars.[citation needed] Stainless steel plate fins have been used in aircraft for 30 years and are now becoming
established in chemical plant.

Originally conceived by an Italian mechanic, Paolo Fruncillo. A plate-fin heat exchanger is made of layers
of corrugated sheets separated by flat metal plates, typically aluminium, to create a series of finned
chambers. Separate hot and cold fluid streams flow through alternating layers of the heat exchanger and are
enclosed at the edges by side bars.

Heat is transferred from one stream through the fin interface to the separator plate and through the next set
of fins into the adjacent fluid. The fins also serve to increase the structural integrity of the heat exchanger
and allow it to withstand high pressures while providing an extended surface area for heat transfer.

A high degree of flexibility is present in plate-fin heat exchanger design as they can operate with any
combination of gas, liquid, and two-phase fluids. Heat transfer between multiple process streams is also
accommodated,with a variety of fin heights and types as different entry and exit points available for each
stream.

The main four type of fins are: plain, which refer to simple straight-finned triangular or rectangular
designs; herringbone, where the fins are placed sideways to provide a zig-zag path;
and serrated and perforated which refer to cuts and perforations in the fins to augment flow distribution and
improve heat transfer.

A disadvantage of plate-fin heat exchangers is that they are prone to fouling due to their small flow channels.
They also cannot be mechanically cleaned and require other cleaning procedures and proper filtration for
operation with potentially-fouling streams.

The cost of plate-fin heat exchangers is generally higher than conventional heat exchangers due to a higher
level of detail required during manufacture. However, these costs can often be outweighed by the cost
saving produced by the added heat transfer.
Plate-fin heat exchangers are generally applied in industries where the fluids have little chances of fouling.
The delicate design as well as the thin channels in the plate-fin heat exchanger make cleaning difficult or
impossible.

Applications of plate-fin heat exchangers include:

 Natural gas liquefaction

 Cryogenic air separation
 Ammonia production
 Offshore processing
 Nuclear engineering
 Syngas production
 Aircraft cooling of bleed air and cabin air
References:-

 https://www.alfalaval.com/products/heat-transfer/plate-heat-exchangers/gasketed-plate-and-frame-heat-
exchangers/#:~:text=The%20heat%20transfer%20area%20of%20a%20gasketed%20plate%20heat%20e
xchanger,as%20seals%20between%20the%20plates.&text=While%20high%20flow%20turbulence%20
between,the%20consequence%20is%20pressure%20drop.
 https://en.wikipedia.org/wiki/Plate_fin_heat_exchanger
 https://www.intechopen.com/books/heat-transfer-studies-and-applications/modeling-and-design-of-plate
-heat-exchanger