HEAT EXCHANGER USED IN
They are piece of equipment for efficient heat transfer.
Media may be separated by a solid wall or they may be in
They may be used in
example of Heat exchanger is found in an Internal
TYPES OF HEAT EXCHANGERS
Shell and tube exchangers.
Double pipe exchanger.
Plate heat exchangers.
Spiral heat exchangers.
Air cooled: cooling and condenser.
Fired and heaters.
SHELL AND TUBE HEAT EXCHANGER
• Common type of heat exchanger in oil refineries
and other large chemical processes.
• It consists of shell(a large pressure vessel) and a
set of tubes inside the shell known as tube
• One fluid runs through the tube and another
fluid flows over the tube to transfer the heat
between the two fluids.
• U-TUBE HEAT
configuration gives a
large surface area in a
A good shape for
It can be easily
STRAIGHT-TUBE HEAT EXCHANGER
ONE PASS TUBE-SIDE
TWO PASS TUBE-SIDE
DOUBLE-PIPE HEAT EXCHANGER
• It is made up of concentric inner and outer
• Cold and hot liquid respectively flows in the gap
of inner pipe and sleeve pipe and hence
exchange the heat at same time.
• Inner pipe- use U-tube to connect.
pipe-use direct pipe to connect both ends.
Structure is simple
transmission is large.
Easy to clean and
Flow rate is
appropriate and it is
possible to have
PLATE HEAT EXCHANGER
• Use metal plates to transfer heat between two
• Fluids are exposed to much larger surface area
because fluid spread out over the plates.
this facilitates the transfer of heat.
increase the speed of temperature change.
GASKETED-PLATE HEAT EXCHANGER
• Consists of a stack of closely spaced thin plates
clamped together in a frame.
• Thin gaskets seals the plates round their edges.
• These exchangers are used in food and beverage
industries as they can be readily taken part in
cleaning and inspection.
• Plate –heat exchanger
Plate thickness -0.5
Gap between plates1.5 to 5mm.
Plate surface area
range-0.03 to 1.5mm.
Plate width: length
ratio-2 to 3mm.
Maximum flow rate
of fluid is limited –
• Plates are attractive when
material cost is high.
• They are easy to maintain.
• Low approach temperature
can be used (as low as 1 degree
• They are more flexible.
• They are suitable for high
• They are not in good shape to
resist pressure (not suitable
for < than 30 bar).
• Selection of suitable gasket is
Plate-fin exchangers consist essentially of plates separated by
corrugated sheets, which form the fins.
• They are made up in a block and are often referred to as matrix
• They are usually constructed of aluminum and joined and sealed
• The main application of plate-fin exchangers has been in the
• such as air separation plants, where large heat transfer surface
areas are needed.
• They are now finding wider applications in the chemical processes
industry, where large surface area, compact, exchangers are
required. Their compact size and low weight have lead to some
use in off-shore applications.
SPIRAL HEAT EXCHANGER
• They are considered as plate heat exchanger in
which plates are formed into a spiral.
• Channels are formed between the plates through
which fluid flows.
• It is made up of long sheets-150-1800mm wide.
and gap between sheets- 4-20mm.
• Channels are closed by gasketed-end plates
bolted to an outer case.
• inlet and outlet nozzles are fitted to the case and
connect to channels.
AIR COOLED:COOLERS AND CONDENSERS
• Air-cooled exchangers should be considered when cooling water is
in short supply or expensive. They can also be competitive with
water-cooled units even when water is plentiful. Frank (1978)
suggests that in moderate climates air cooling will usually be the
best choice for minimum process temperatures above 650 c, and
water cooling for
• minimum processes temperatures below50 C. Between these
temperatures a detailed
• economic analysis would be necessary to decide the best coolant.
Air-cooled exchangers are used for cooling and condensing.
• Air-cooled exchangers consist of banks of finned tubes over which
air is blown or drawn
• by fans mounted below or above the tubes (forced or induced draft).
Only small rates of heat
transfer is required.
Storage vessels is used to
maintaining the temperature of
It is also used to promote heat
transfer in vessels.
These are considered
when cooling water is in
short supply or expensive.
These are used when high
temperature and high flow
rates are required.
Capacity of these heaters
3 to 100MW.
These heaters are directly
heated by the products of
combustion of a fuel.
Process feed-stream heaters; 60% of the feed vaporized.
Reboilers for the columns used small size direct-fired
Reformers for hydrogen production.