Effect of melting point on thermodynamics of thin PCM reinforced residential frame walls in different climate zones

Abstract

Energy consumption in building sector has increased dramatically over the past two decades. The incorporation of phase change materials (PCMs) into building envelopes is considered as an effective thermal energy storage strategy to improve building thermal performance and reduce space heating/cooling load. Despite significant efforts in PCMs technologies and their applications to buildings, how to effectively improve energy efficiency of latent heat generated from PCMs for building energy and how to select proper PCMs for buildings under different climate zones still post great challenges. Lack of systematic and comprehensive studies in these gaps hinder their broad applications in the building sector. To meet the need, this study aims to numerically explore the impacts of critical design parameters including PCM layer location, thickness, and the loading conditions associated with different climate zones and months on the selection of the PCM melting point. COMSOL Multiphysics® software is used to simulate multilayer walls containing PCM to unveil the thermal performance under various climate loading conditions. The results reveal that selecting proper PCM melting point according to those design parameters reduces the indoor peak temperature and temperature oscillation, and thus diminishes the energy consumption by the heating, ventilation, and air conditioning (HVAC) system to regulate the indoor temperature. The optimal PCM melting point is in direct proportion to the input loading conditions, suggesting that a higher PCM melting point is needed for a building envelope subjected to higher input temperature associated with climate zones. Results also show that PCM with a melting point within the occupant thermal comfort zone can increase indoor thermal comfort duration more effectively for the “moderate” climate loading conditions. The findings are expected to assist engineers with better utilization of the PCM-based building envelope in different climate regions.