How phase change materials affect thermal performance: Hollow bricks

The enhancement of rooftop thermal-insulation capability is a key issue in energy conservation in hot and humid climates, where flat roofs receive the greatest solar heat gain. During the process of melting or solidification, a phase change material (PCM) can effectively release or store a great amount of latent heat. As a result, PCM has often been applied for the purpose of environmental control. Experiments analysed the effects on thermal characteristics of adding PCM to conventional hollow thermal-insulation bricks. Two identical test models with untreated and PCM-treated bricks, respectively, were located nearby in field. They were exposed to solar radiation at the same time on typically clear summer days. PCM-treated bricks had a better daytime thermal insulation effect than ordinary hollow bricks. When the maximum outdoor temperature was 35.5°C, the maximum underside temperature of PCM-treated bricks was 31.7°C, which was 4.9°C lower than that of the untreated bricks. In addition, PCM-treated bricks can provide more effective indoor heat preservation at night when temperatures fall outdoors.