Inverse Problem Method to Optimize Cascade Heat Exchange Network in Central Heating System

In central heating systems, heat is often transferred from heat source to users by the heat network where several heat exchangers are installed at the heat source, substations, and terminals. In this article, the mathematical optimization model of the cascade heat exchange network with three-stage heat exchangers in a series is established. The aim is to maximize the cold fluid temperature for a given hot fluid temperature and overall heating capacity, the optimal heat exchange area distribution, and the medium fluid flow rates are determined through an inverse problem and variation method. The results show that the heat exchange areas should be distributed equally for each heat exchanger. It also indicates that in order to improve the thermal performance of the whole system, more heat exchange areas should be allocated to the heat exchanger where flow rate difference between two fluids is relatively small.