A novel thermal management strategy for building envelopes: Design and performance evaluation of composite walls integrated with phase change radiation unit

Abstract

When phase change material (PCM) are passively integrated into building envelopes, thermal hysteresis and the low thermal conductivity of PCM extend the heat absorption/release cycle, thereby reducing the ability of PCM to regulate the indoor environment under summer external disturbances. This paper proposes a strategy involving the use of phase change materials with enhanced thermal conductivity within radiation cooling panel to form phase change radiation unit. These unit, when combined with conventional building walls, create an active phase change wall (APW), introducing a new thermal management system for building envelopes. First, a sensitivity analysis was conducted to assess the impact and importance of the parameters of composite phase change material (CPCM) on the heat gain of the inner surface. Subsequently, the thermal performance of the APW was systematically studied by varying the transition temperature, transition temperature range, and parameters (latent heat, thermal conductivity and thickness) of CPCM. The results show that incorporating APW enhances the thermal storage and regulation capabilities of the building. Compared to traditional building walls, the thermal storage and adjustment capability (TSAC) value increased by an average of 144.1 %. Sensitivity analysis indicates that the transition temperature of PCM is the primary factor affecting heat gain, followed by parameters such as thickness, latent heat, and density, while the effect of specific heat capacity on heat gain is negligible. Additionally, an increase in latent heat and thickness significantly affect thermal performance, but their increases should not exceed a certain threshold. It is recommended that the thermal conductivity should be between 1–3 W/(m·K), the transition temperature be 26 °C, and the transition temperature range be 4 K.