Experimental study of breathable and heterogeneous phase change material (B&H-PCM) wall for all-season thermal performance enhancement

Abstract

Physical parameters of existing building walls are relatively stable, making it difficult to meet the thermal requirements under different seasons. In this study, phase change materials (PCMs) with different thermal conductivities and melting points were adopted to form a breathable heterogeneous phase change material (B&H-PCM) wall to achieve the year-round heating and cooling load reduction. The effects of operation parameters on B&H-PCM and ventilated block (VB) wall were experimentally analyzed. As the hot air inlet temperature rose from 30 to 80 °C in winter, the heat storage capacity and liquefaction ratio continuously increased. The PCM heat storage rate was maximized at 50 °C with 26.7 %, and the liquefaction ratio of internal PCM was 100 % at 60 °C. As the air inlet velocity went up in winter/summer, the heat storage/dissipation capacity increased and the heat storage/dissipation rate changed oppositely. The maximum heat storage rate was 36 % at 0.5 m/s in winter, and the maximum heat dissipation rate was 58.7 % at 3 m/s in summer. The external/internal heat capacity and thermal resistance of B&H-PCM wall were 5.9/7.2 and 1.1/0.8 times of VB wall respectively, indicating that B&H-PCM wall had a better heat storage and resistance capacity both in winter and summer.