Characteristics optimization of composite phase-change wall during intermittent heating process

Abstract

The indoor thermal environment under an intermittent heating condition can be maintained by rationally utilizing the heat storage and release processes of the composite phase-change wall (composite-PCW), leading to heating time and energy consumption reductions. In order to optimize its heat storage and release processes, the influences of different parameters on the dynamic thermal processes of composite-PCW were studied, including the position and thickness of phase-change material (PCM), phase transition temperature, phase-change latent heat, and PCM thermal conductivity, according to two typical intermittent conditions summarized by experimental data. With large heat storage efficiency η and small heat loss rate ε, the optimized composite-PCW that was adaptive for intermittent heating was the composite-PCW with 10 mm PCM integrated to the wall inside. Its phase-transition temperature was 19–20 °C (66.2–68 °F), the phase-change latent heat was 220 kJ/kg (95.58 btu/lb), and the thermal conductivity was 0.4 W/(m·K) (0.23 btu/(ft·h·°F)) at liquid states and 0.8 W/(m·K) (0.46 btu/(ft·h·°F)) at solid states.