Thermodynamic optimization of geometric structure in the counterflow heat exchanger for an environmental control system

This paper shows that the internal geometric configuration of a component can be deduced by optimizing the global performance of the installation that uses the component. The example chosen is the counterflow heat exchanger that serves as condenser in a vapor-compression-cycle refrigeration system for environmental control of aircraft. The optimization of global performance is achieved by minimizing the total power requirement or the total entropy generation rate. There are three degrees of freedom in the heat exchanger configuration, which is subjected to two global constraints: total volume, and total volume (or weight) of wall-material. Numerical results show how the optimal configuration responds to changes in specified external parameters such as refrigeration load, fan efficiency, and volume and weight. In accordance with constructal theory and design [1], it is shown that the optimal configuration is robust: major features such as the ratio of diameters and the flow length are relatively insensitive to changes in the external parameters. (C) 2001 Elsevier Science Ltd. All rights reserved.