Performance of a Simplified Computational Fluid Dynamics Model for a Phase Change Material-Water Finned Heat Exchanger Under Different Orientations

Abstract

The prevalent numerical models for simulating axially finned heat exchangers with phase change materials (PCMs) and water asthe heat transfer fluid rely on computational fluid dynamics (CFD) techniques, with a primary focus on phase change modeling.However, the computational demands of these models, incorporating phase change effects and resolving PCM movement in theliquid state, are substantial. From experiments suggesting that conduction in the solidified PCM around the finned tube domi-nates heat transfer during the heat discharge process, this article introduces a simplified CFD-based model in which convectiveflow of the PCM is neglected. The model is experimentally validated using a 1-m-long axially finned heat exchanger prototypewith four fins, recording temperatures under different water flow rates and orientations (horizontal and vertical). Results showthat the proposed model predicts outlet water temperature satisfactorily, with absolute errors below 1.0°C and 2.2°C for the hori-zontal and vertical orientations, respectively. Additionally, the model can capture the temperature trend inside the PCM for thehorizontal orientation.