Page 298 - Design and Operation of Heat Exchangers and their Networks

284 Design and operation of heat exchangers and their networks

Example H2C4
This example is also taken from Bjork and Westerlund (2002). The problem
data are listed in Table 6.20. Their reported TAC was 139,083$/yr;
however, the network was not given. Till now, the best network was
obtained by Huang and Karimi (2012, 2013) with the simultaneous
synthesis approach based on the stagewise hyperstructure. The network is
shown in Fig. 6.20, which contains three splits and one bypass. There are
six independent variables, which can be optimized. The revised TAC of
the network is 122,940$/yr.

Table 6.20 Problem data for H2C4 (Bjork and Westerlund, 2002).
2
_
Stream T in (°C) T out (°C) C (kW/K) α (kW/m K) Cost ($/kWyr)
H1 180 75 30 2
H2 240 60 40 2
C1 40 230 20 1.5
C2 120 260 15 1.5
C3 40 130 25 2
C4 80 190 20 2
HU 325 325 1 120
CU 25 40 2 20
2
Heat exchanger cost¼8000+50A 0.75 $/yr (A in m )
Total annual cost ($/yr)
Solutions in the literature Reported Revised
Huang and Karimi (2012, 2013) 123,398 122,940
Bjork and Westerlund (2002) 139,083 –
Bergamini et al. (2007) 140,367 131,692

22.65 2250
180 75
H1
(30)
(29.51761) 3777
240 (20.03153) 60
H2
(40)
(21.16799)
230 40 C1
305 (20)
305 (19.83485)
260 120
C2
(15)
877.3 453
130 917.8 743 40 C3
(25)
190 80
C4
(20)
2200
Fig. 6.20 Optimal solution for Example H2C4 (Huang and Karimi, 2012, 2013),
TAC¼ 122,940$/yr.