Design method of general heat exchanger networks with heat pumps based on thermal energy discretization and matching

Abstract

The design method of a general heat exchanger network with heat pumps (GHEN) is significant owing to its wide application in different industrial and building processes. However, the thermal energy grade of the energy pocket cannot be fully used in the pinch method, and the thermodynamic meaning of the optimal solution cannot be clearly explained by the mathematical programming method. In this paper, a design method with as little high-grade energy use as possible is proposed for GHENs based on thermal energy discretization and matching (TEDM). This method obeys thermodynamic laws and designs GHENs through programming. Two types of advanced systems, an absorption heat exchanger and a composite district heating substation, were designed using the TEDM method to demonstrate its correctness and practicability. The energy and economic performance of a GHEN in an actual scenario were analyzed and compared with a system designed using the pinch method. The results indicated that the advanced systems presented in the literature can be easily constructed using the TEDM method. Compared with the system designed using the pinch method, the exergy consumption and operational cost of the system designed using the TEDM method decreased by 14.9% and 30.9%, respectively. The TEDM method provides a more promising alternative to the pinch method for the design of GHENs.