Performance prediction of plate fin heat exchangers: A CFD and NTU-based approach

Compact heat exchangers play a major role in the heat transfer processes of aircraft air cycle systems, where their performance significantly influences on overall system effectiveness. Accurate performance prediction is crucial for optimizing both the heat exchanger and the air cycle systems. Traditional experimental methods for evaluating the performance of compact heat exchangers are resource-intensive and time-consuming, rendering them unsuitable for rapid design processes. This study proposes a performance prediction method combining the number of heat transfer unit (NTU) approach with computational fluid dynamics. A NTU model, based on the heat transfer characteristics of the fins, is constructed by improving the experimentally fitted NTU model previously developed by our research group. In this improved model, experimentally fitted parameters in the original model are replaced with numerical Colburn heat transfer factor of the fins. By eliminating dependence on experimental data, the method enhances the efficiency and accuracy of heat exchanger performance predictions. The proposed approach is validated on a ground experimental platform, with tests conducted on heat exchangers with three typical types of fins. Results show that the average error between predicted and experimental values is under 3 %. Furthermore, the validated method is used to predict the heat exchanger performance under various operating and structural conditions. The method proposed in this study provides an efficient solution for the design, optimization, and application of compact heat exchangers.