Scribd
Upload
7 views9 pages

Week-12-Lec 1

The document discusses the fundamentals and design analysis of heat exchanger networks (HEN), emphasizing the pinch technique for heat integration to minimize utility usage. It outlines the synthesis of HEN, including the basic assumptions and goals such as minimizing the number of heat exchangers and optimizing stream matching. A test case with stream data is provided to illustrate the application of the pinch technique in designing efficient heat exchanger networks.

Uploaded by

Sreeram Gottumukkala
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
7 views9 pages

Week-12-Lec 1

The document discusses the fundamentals and design analysis of heat exchanger networks (HEN), emphasizing the pinch technique for heat integration to minimize utility usage. It outlines the synthesis of HEN, including the basic assumptions and goals such as minimizing the number of heat exchangers and optimizing stream matching. A test case with stream data is provided to illustrate the application of the pinch technique in designing efficient heat exchanger networks.

Uploaded by

Sreeram Gottumukkala
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 9

Heat Exchangers: Fundamentals and Design Analysis

Heat Exchanger Network Analysis by Pinch Technique


Prof. P. K. Das.
Mechanical Engineering
IIT KHARAGPUR

Reference: The Pinch Design Method For Heat Exchanger Networks by B. Linnhoff and E. Hindmarsh
Chemical Engineering Science Vol.38, No.5, pp.745-763, 1983

1
Heat Exchanger Network
Process Plant:
 Many streams need heating or cooling.
 Utilities like hot air , hot oil, steam for heating.
 Utilities like air, water, chilled water, refrigerant for cooling.
 Efforts to be made for reducing the use of utilities.
 This can be done by “ Heat Integration” .
 “ Heat Integration” implies heat exchange between the hot and cold streams.
 This reduces the use of utilities.
 However, this increases the number of heat exchangers.
 Heat exchanger synthesis means designing a network so that using minimum
number of heat exchangers, the use of utilities can also be minimized

2
Synthesis of Heat Exchanger Network (HEN)

 There are different techniques of synthesis of HEN.


 The pinch technique is very widely used.

3
Schematic representation of Heat Exchanger Network

C1 C2 C3
H1 RULE:
Minimum number of Heat
H2 Exchangers (𝑈𝑚𝑖𝑛 ) = 𝑁-1
𝑁=No. of process streams ( N1 ) + No.
H3
of utilities(N2)

4
Pinch Technique
Basic assumptions for present discussion:
 Logic Based- based on first and second law of thermodynamics.
 There is one hot utility and one cold utility of infinite capacity.
 Steady state operation.
 There is no restriction for matching the streams.
 All heat exchangers are without any phase change and without any heat generation or
reaction.
 Heat exchangers are assumed to be indirect contact and counter flow.

5
Table 1. Stream data for test case
STREAM NUMBER & HEAT CAPACITY FLOW RATE 𝑪𝒑 TS(℃) TT(℃)
TYPE kW/℃

(1) HOT 2 150 60

(2) HOT 8 90 60

(3) COLD 2.5 20 125

(4) COLD 3.0 25 100

𝜟𝑻𝒎𝒊𝒏 = 𝟐𝟎° 𝑪

6
4
3

2
1

20 ℃ 25 ℃ 60 ℃ 90 ℃ 100 ℃ 125 ℃ 150 ℃


Temperature
Goals of HEN synthesis
1) Minimum utility.
2) Stream matching.
3) No. of heat exchangers needed.
4) End temp of the heat exchangers.

7
T

Cold Hot
Utility Utility

8
Thank You!!

10

You might also like