A plate type heat exchanger consists of corrugated metal plates clamped together in a frame. Fluids flow between the plates, which have a high surface area and induce turbulence, allowing for efficient heat transfer. Key advantages are compact size, ability to handle low flow rates, and the option to perform multiple duties with one unit. Design involves selecting the number and dimensions of plates based on flow rates, properties of the fluids, and heat transfer correlations or manufacturer charts.

1. DESIGN CONSIDERATIONS FOR
PLATE TYPE HEAT EXCHANGER
Arun S
CHEMICAL ENGINEERING

2. What is a plate type heat exchanger?
It’s a type of Heat Exchanger which consists of many corrugated
stainless-steel sheets separated by polymer gaskets and clamped into
a steel frame
•Plate heat exchangers transfer heat by placing thin, corrugated metal
sheets side by side and connecting them by gaskets.
•Flow of the substances to be heated and cooled takes place between
alternating sheets allowing heat to transfer through the metal sheets.

3. Assembly
 Instead of pipe passing through chamber, there are two
alternate chambers separated by a corrugated plate
 Plates are usually spaced by rubber gaskets
 The plates are pressed to form troughs at right angles to
the direction of flow of liquid which runs through the
channel
 Plates produce a large surface area ensuring maximum
heat transfer
 The number and size of the plates are determined by the
flow rate, physical properties of the fluids, pressure drop,
and temperature
 Mainly two forms of corrugations are seen
◦ Intermating corrugations
◦ Chevron corrugations

4.  The frame and the channel plates have portholes that allow process
fluids to enter altenating flow patterns
 These narrow gaps and high number of contact points which
change fluid flow direction combine to create a very high turbulence
between the plates.
 For a liquid-liquid heat exchanger whose usual fluid velocity is 0.2 to
1 m/s, the Reynolds No will be< 2100, but due to the presence of
corrugations the turbulent characteristics are achieved even at NRe
say about 400-500.
 Evidence of Turbulent characteristics is obtained by measuring heat
transfer coefficient which varies with 0.6 to 0.8 power of flow rate
and pressure which varies with 1.7 to 2 power of the flow rate
General Dimensions of PHE

5. Why Plate Heat Exchanger?
 High heat transfer area
 High heat transfer coefficient
 Compact and has lower floor space
requirements.
 By increasing the number of plates the area of
heat exchange can be increased
 Most suitable type heat exchangers for lower
flow rates and heat sensitive substances.
 Multiple duties can be performed by a single un

6. Design using correlations
 From the APV heat transfer handbook- Design and Application of
Paraflow- Plate Heat exchangers there are following correlations for
PHEs:
Where Np is the number of passages
w is the width of the plate
W is the mass flow rate
G is the mass velocity

7. Design using charts
 Only limited design correlations are available for the design of Plate
heat exchanger
 So the preliminary design is on the basis of certain charts by the
manufacturers.
 As per designing of plate and frame filter press by Christopher
Haslego, they introduced a set of certain charts which form the
basis of preliminary design.
 The use of the charts were on the basis of following points:
◦ Applicable for liquid-liquid design
◦ Valid for only single pass units
◦ Thermal conductivity of wetted material is same as that of SS
◦ For fluids with viscosity between 100cP to 500 cP , the 100 cP
line in the graph should be used.

8. A = q/U LMTDF.
the number of plates from, N=A/Ap, where A, is the area of a plate

11. Plate Fin Type Exchanger

12. Limitations…..
 Cost factor is on the higher side as most of the parts are
made of SS.
 Not suitable for liquids with high viscosity and
suspended matters.
 Often Fouling in plates, leads to requirement of
intermittent cleaning and this reduces the life of gaskets.
 Large difference in fluid flow rates cannot be handled.

13. Applications
 Widely used in diary and food
processing industries
 A whole heat exchange network can
be condensed to a plate heat
exchanger
 Pasteurisation of milk uses the plate
heat exchanger with three- four
sections
 Also used in food and cosmetics
industries.

14. References
 Perry’s Chemical Engineering
Handbook ,8th Edition,Don.W.Green,
Robert.H Perry
 Unit Operations of Chemical
Engineering, Seventh Edition,
Warren.L.McCabe, Julian.C.Smith
 Designing Plate and Frame Heat
Exchanger, Christopher Haslego and
Graham Polley