Thermal analysis of a composite wall with reflective materials, phase change materials and autoclaved aerated concrete

In order to reduce the heat gain of the building envelope in summer, a novel composite wall (ARPCM) incorporating autoclaved aerated concrete (AAC), phase change materials (PCMs), and reflective materials is proposed and fabricated, which enables it to reflect solar radiation during the daytime, store heat, and dissipate heat through radiation at night. In this study, the primary experiments were conducted to determine the absorptivity/emissivity of the reflective materials and the DSC of the PCM. Next, a mathematical model of the ARPCM wall was established and validated against field measurements with good agreement. Afterwards, a systematic parametric studies examined key factors including reflectivity of reflective materials, PCM thickness, and placement location. The results illustrated that: (1) ARPCM walls with reflectivity of ρ=0.7, 0.5, and 0.3 exhibited interior surface temperatures that were 0.31 °C, 1.06 °C, and 1.45 °C higher than those of the reference wall (ρ=0.8), (2) the temperature oscillation of the ARPCM wall with the PCM installed on the inner side is 0.15 °C, and the decrement factor is 0.9%. In addition, in the design of ARPCM walls, it is essential to enhance the solar radiation reflectivity of surface reflective materials, position the PCM layer on the outer structural layer of the wall, and moderately increase its thickness, to effectively reduce the wall’s heat gain in summer. Overall, the ARPCM wall exhibited good potential in engineering applications.