Influence of PCM design parameters on thermal and optical performance of multi-layer glazed roof

Abstract

Phase change material (PCM) applied in the multi-layer glazed roof can decrease energy consumption of building and increase thermal comfort by improving its thermal energy storage capacity. In present work, a numerical model was developed to provide a tool to determine thermal and optical performance of a multi-layer glazed roof filled with phase change material for developing engineering analyses. The model was validated by the experimental results measured in a multi-layer glazed roof test facility. The influences of air convection and PCM design parameters on thermal and optical performance of the multi-layer glazed roof filled with PCM were also investigated by the model. The results show that a good agreement was obtained between experimental data and simulations. The influence of air convection on the thermal and optical performance of multi-layer glazed roof is weak for different PCM melting temperatures and thicknesses, except for its effect on the interior temperature. Considering that the maximum and minimum interior temperatures are key parameters to analyze the thermal performance of multi-layer glazed roof, the air convection process should be considered. The influences of PCM thickness and melting temperature on optical performance are big. The PCM thickness has also serious influences on the thermal performance, which include interior temperature, temperature time lag, temperature difference of the interior surface and the upper surface of air layer, and total transmitted energy. With the PCM thickness increasing, the variation of temperature difference of the interior surface and the upper surface of air layer in one day experiences multiple peaks and troughs. Considering influence of PCM design parameters on both thermal and optical performance of glazed roof, thickness of 12–20 mm and melting temperature of 16–18 °C was recommended.