Dual-mode passive thermal management for outdoor electrical houses based on the coupling of phase change thermal storage and radiative cooling

Outdoor electrical houses face significant challenges of thermal accumulation under high-temperature conditions, which can lead to equipment failure and threaten grid stability. To address this issue, this study introduces a dual-mode passive thermal management strategy using a phase change-radiative cooling coupled material (PCM-RC) applied to building envelopes. The material combines a shape-stabilized phase change material (PCM) base with high latent heat (106.32 kJ/kg) and a radiative cooling (RC) overlay featuring high solar reflectance (91 %) and strong mid-infrared emissivity (93 %). A silane coupling agent enhances interfacial adhesion between the two functional layers. The RC layer minimizes solar heat gain through high reflectivity and continuous radiative heat dissipation, while the PCM layer provides transient thermal storage through latent heat absorption, thereby delaying indoor temperature rise and attenuating heat flux penetration. Experimental tests under ambient temperatures above 40 °C show that the PCM-RC coating remarkably reduces roof and wall surface temperatures by up to 19.9 °C and 17.3 °C, respectively, compared to conventional enclosures, maintaining indoor electrical equipment within a safe operational temperature range. This work demonstrates a feasible and efficient approach to passive thermal management for electrical infrastructure, with strong potential for application in practical engineering fields involving rigorous thermal regulation and temperature control.