Analysis of the Dynamic Characteristics of Cross-Flow Heat Exchangers with Both Fluids Unmixed : On the Transient Responses to a Step Change in the Inlet Temperature

Abstract

The transient responses to a step change in an inlet temperature are analyzed as an important example of dynamic characteristics of cross-flow heat exchangers with both fluids unmixed. The numerical calculations are performed by two methods, namely, a method expanding a finite difference method used by Myers et al. to calculate accurately in the case where temperature changes discontinuously, and a central finite difference method to calculate more accurately with a small number of nodes in large values of a heat capacity of a solid wall. Consequently, the effects of an initial condition and the various parameters concerning heat transfer performance on the transient responses in the temperature efficiency are shown.