Experimental study on the heat transfer characteristics of different walls with phase change materials in summer

Abstract

The incorporation of phase change materials (PCMs) into building walls is a novel strategy for reducing heating and cooling energy consumption. The location of the PCM layer has an important influence on the non-stationary heat transfer characteristics and insulation performance of the wall. In this study, a novel experimental device was designed to test PCM and normal walls simultaneously in a two-sided artificial environment. This aimed to avoid the errors that occur when such walls are tested separately. Brick walls were constructed with a PCM layer on the outside, middle (sandwiched), or inside of the wall. One side of the wall was subject to a fluctuating air temperature to simulate summer outdoor conditions, while the other side was subjected to a constant temperature to simulate indoor air-conditioned conditions. Using sensors placed at various locations on the walls and test apparatus, characteristics such as temperature distribution and surface heat flow density were tested. The wall with the PCM layer on the outside surface exhibited the best insulation performance. Compared with ordinary wall, the maximum temperature of its inner surface was 0.2 °C lower, its surface heat flow density was 19.6% lower, its average heat transfer coefficient was 19.94% lower, and its temperature delay time was 1.33 h longer. The conclusions of this study provide a basis for determining the optimal location for PCM layers on building walls.