–(33))。 Also for the same reason, all the values related to cost are taken from the work of Caputo et al。 [6] who tried all the case studies by GA approach。 

In the SA approach upper and lower bounds for the optimization variables are given in Table 1。 All the values of discounted operating costs are computed with ny = 10 yr, annual discount rate (i) = 10%, energy cost (Ce) = 0。12 €/kW h and an annual amount of work hours H = 7000 hr/yr。 

Table 3 shows the optimized parameters of the case studies obtained using SA and comparison with the optimized parameters obtained by Caputo  et  al。 [6] using GA approach, while Figure 3 shows the cost comparison of both the approaches for all the three  case studies。 From Table 3 it is clear that the pro- posed SA approach has ability to reduce the total cost 

Table 2。 Process inputs and physical properties for different case studies 

–3 –1     –1

–1     –1

2 –1

Condition Mass flow, kg/s   Tinput / C   Toutput / C    / kg m    Cp / kJ kg   K    / Pa s   K / W m   K      Rfouling / m  K  W   

Case 1 

Shell side: methanol 27。80 95。00 40。00 750。00 2。84 0。00034 0。19 0。00033 

Tube side: sea water 68。90 25。00 40。00 995。00 4。20 0。0008 0。59 0。0002 

Case 2 

Shell side: kerosene 5。52 199。00 93。30 850。00 2。47 0。0004 0。13 0。00061 

Tube side: crude oil 18。80 37。80 76。70 995。00 2。05 0。00358 0。13 0。00061 

Case 3 

Shell side: oil 43。60 114。00 66。00 820。00 2。17 0。00024 0。13 0。00070 

Tube side: cooling water 45。38 26。00 50。00 993。00 4。17 0。00068 0。63 0。00015 

Table 3。 Optimal heat exchanger geometry using different optimization methods