Analytical model of a PCM-air heat exchanger

This paper presents an analysis of a tubular heat exchanger which utilizes the latent heat of a phase-change material (PCM). In the heat exchanger, the PCM melts inside tubes while air flows across the tube banks. The sensible heat capacity of the liquid PCM and the tubes' material is considered small in comparison with the latent heat of melting. This assumption allows to derive and solve a system of partial differential equations which describe heat transfer and melting of the PCM inside the tubes and heat transfer in the air for the entire system. An analytical solution is obtained and compared with the results of a numerical solution. Simple formulas are found for the overall heat exchange parameters, like heat transfer rate, stored energy and total melting time. In addition, the model predicts the results for separate tubes depending on the tube location in the system. The effect of the model assumptions on the results and applicability of the analytical solution to the real heat exchangers are demonstrated.