A new model for plate heat exchangers with generalized flow configurations and phase change

A new model has been developed for the analysis of plate heat exchangers with multi-fluid, multi-stream and multi-pass configurations. The model divides the entire heat exchanger into multiple slices in the direction of fluid flow. For the channels in each slice, the wall temperatures are assumed to be constant such that each channel can be solved without the need of knowing the fluid condition in the adjacent channels. In the top level, all the slices are iterated using a successive substitution approach. The model is capable of handling both single-phase and two-phase flow. In general, plate heat exchangers are used with two to three fluids, but the model is capable of handling more than three fluids wherein each fluid can undergo phase change. The model was verified against the P-NTU closed form expressions for single-phase flow in plate heat exchangers with various flow configurations. The model was validated against in-house experimental data for single-phase water, two-phase ammonia and R22 boiling. The effect of discretization and the speed up on multiple cores was investigated.