Proposed Modifications for Models of Heat Transfer Problems Involving Partially Melted Phase Change Processes

Abstract

Abstract Air conditioning electricity consumption in summer represents a challenge in many areas with hot and humid climates. When incorporated into lightweight residential building walls, phase change materials (PCMs) can increase the effective thermal mass of the wall, which in turn will shift part of the cooling load to off-peak times and lower the peak space cooling load of the building. From analyses of experimental data, it was found that it was very likely that the PCMs, once integrated into the walls, would “start” the phase change process from partially melted states. Currently used simulation models, including the most widely accepted models, such as the effective heat capacity method and the enthalpy method, come short when handling phase change processes that start from partially melted states. The characteristics of how the heat is absorbed or released during the phase change process were studied through experimental and theoretical analyses. A differential scanning calorimeter (DSC) method and its detailed steps, used to obtain latent heat of fusion distribution along the phase change temperature range, are presented. Based on the DSC test data, a modified PCM model for a paraffin-based PCM was developed.