Thermal performance evaluation of a compact two-fluid finned heat exchanger integrated with cold latent heat energy storage

Abstract

To alleviate the mismatch between thermal energy supply and demand, the use of latent heat thermal energy storage of phase change materials is a reliable and effective solution in thermal systems. The present work aims to introduce an innovative finned-plate air-liquid heat exchanger with phase change material partially embedded in the fins' gap providing airside cooling by thermal energy storage during coolant shutdown periods. The thermal performance and accompanying phase change process are studied using a three-dimensional computational fluid dynamic approach. The developed model is validated with corresponding experimental data at the same geometry and operating conditions. The system performance is examined time-dependently considering the charging/discharging processes of the phase change material. The effect of air mass flow rate variation is studied, and the results are discussed in terms of fluids temperature, heat transfer rates, and the phase change material phase transition process. The results demonstrate that the heat exchanger stores excess thermal energy during the charging process, which is later discharged for air cooling during demand periods. It is observed that the use of phase change material provides a cooling load of 188 kJ and over 9 min of extra cooling time for the airside in the discharging process. The share of latent heat transfer in the discharging process is calculated at an average of 54% of the total heat transfer. Obtained results reveal that increasing the air mass flow rate can reduce the rate of discharged cold thermal energy and cooling time. The presented thermal management system offers a unique solution to manage passenger thermal comfort in hybrid and electric vehicles with a start-stop function. The introduced system could provide efficient cabin air cooling and enable effective energy savings during short periods of engine shutdown.