Heat storage process analysis in a heat exchanger containing phase change materials

Abstract

• One of the most effective methods of thermal energy storage is the use of phase change materials (PCMs). • The highest thermal energy storage in these materials occurs during the phase change process. Accurate analysis of the PCMs behavior will result in the optimal use of these materials. • The performance of a shell and tube heat exchanger containing PCMs is analyzed using the modeling results of PCMs. • The effect of PCMs type, HTF temperature, heat exchanger outer diameter, and fins number are analyzed. The need for energy storage has increased due to increased energy consumption and unbalanced consumption curves. The energy storage improves the availability and efficiency of energy resources. One of the most effective methods of thermal energy storage is the use of phase change materials (PCMs). PCMs are organic or inorganic compounds capable of absorbing and storing latent heat within themselves. The highest thermal energy storage in these materials occurs during the phase change process. Accurate analysis of the PCMs behavior will result in the optimal use of these materials. In this paper, the performance of a shell and tube heat exchanger containing PCMs is analyzed using the modeling results of PCMs. The Crank-Nicolson numerical solution in MATLAB software is used to solve the heat transfer equations with governing boundary conditions. After confirming the validation of the proposed method, the effect of PCMs type, the heat transfer fluid (HTF) temperature, the heat exchanger outer diameter and fins number on the heat exchanger performance is analyzed. The results showed that, the use of materials with more latent heat leads to store more thermal energy in the lower temperature ranges. Also, as the HTF temperature increases, the temperature difference between the HTF and the PCM increases and therefore, the amount of stored energy and the speed of energy storage will increase. It is also shown that, by increasing the number of fins and the use of six fins instead of four fins, the amount of equilibrium temperature and stored thermal energy will increase.