Numerical Analysis of Double Pipe Heat Exchanger Using Different Internal Pipe Material in the melting process of PCM

Abstract

This study investigated the full melting times of Phase Change Materials (PCMs) stored in the space between two pipes in a double-pipe heat exchanger using a two-dimensional computational fluid dynamics (CFD) model. CaCl₂.6H₂O and Na₂SO₄.10H₂O, salt hydrates in the inorganic group, were used as PCM in the intermediate space. The inner pipe material through which the heat transfer fluid passes was changed in the heat exchanger and analyses were continued for aluminum and copper. The melting thermal behavior of the heat exchanger, which is designed as a thermal energy storage unit with CFD analysis, is modeled under optimum design conditions created according to the enthalpy-porosity approach. As a result, in the heat exchanger where CaCl₂.6H₂O is used as PCM, the full melting times of PCM were measured as 105 and 115 minutes if the inner tube was copper and aluminum and 130 and 140 minutes, respectively, when Na₂SO₄.10H₂O was used. In the case of using copper instead of aluminum as the inner tube material, it was observed that the melting time shortened by 8.7% in the heat exchanger with CaCl₂.6H₂O and by 7.1% in the heat exchanger with Na₂SO₄.10H₂O