Total cost target for heat exchanger networks considering simultaneously pumping power and area effects

A total cost targeting method based on pinch technology for heat exchanger network (HEN) synthesis is presented, which combines existing targeting methods for the grass-roots design problem with a new method for simultaneous targeting of network area and pumping power cost (i.e., optimum pressure drops of streams). The overall targeting problem is formulated so as to minimize the total annual cost, which includes the capital costs of heat exchangers and pumping devices, as well as the utilities costs and the electricity costs to run the pumping equipment. This leads to a problem that can be solved as a non-linear optimization problem for a specified minimum approach temperature. The resulting solution of this mathematical model gives the optimal values of pressure drops and match-dependent heat-transfer coefficients of the streams. Thus, no assumed heat-transfer coefficients or fixed allowable pressure drops need to be used, as is the case with previous targeting methods based on pinch technology. Two examples are presented to illustrate the capabilities of the proposed method.