Experimental Study On Sunshading Plate Solar Phase- Change Heat Collector

Shading is one of the main ways of building passive heat insulation. Solar and building integration technology is the main development direction of the solar energy utilization in the building.In this paper a new solar phase-change heat collector which integrated with the sunshading plate was designed and studied by detail experiment. A test platform for test the heat collecting performance and thermal insulation properties was built and the performance of heat collecting and the properties of thermal insulation was tested in detail. According to the experimental test the heat collecting performance, the thermal insulation properties and the influence factors were derived under the different structural patterns. The optimization programs and suggestions for improving the heat collecting performance and themal insulation property were proposed.The new solar phase-change heat collector could provide a new engineering application model.The experiment includes three groups of structural patterns based on sunshading plate surface color and the filled material of sunshading plate. Structural pattern 1, Silver surface and MG 58 phase-change material filled. Structural pattern 2, Black surface and MG 58 phase-change material filled. Structural pattern 3, Black surface and steel scrap filled. Each structural pattern includes two variables, the intensity of solar radiation and water flow in heat collection pipe.Heat collecting performances:The cumulative heat collections of three structural pattern of solar heat collector were 720.0kJ/m2～1740.0kJ/m2,780.0kJ/m2～2020.0kJ/m2 and 780.0kJ/m2～1940.0kJ/m2. The heat collecting efficiencies of three structural pattern of solar heat collector were 4.0%-11.8%,4.6%～12.3% and 4.2%～13.2%.The cumulative heat collection of solar heat collector grows linearly with the increase of the radiation intensity. The heat collecting efficiency of solar heat collector reduces with the increase of the radiation intensity. The cumulative heat collection and the heat collecting efficiency both grow linearly with the increase of water flow. Thermal performance of the solar heat collector increase after surface color of sunshading plate is painted black. The average improve rate of cumulative heat collection is 13.1%. The average improve rate of heat collecting efficiency is 0.8%. Replacing MG58 phase-change material by steel scrap, the growth rate of cumulative heat collection growing linearly with the radiation intensity increase goes lower. The growth rate of cumulative heat collection growing linearly with the water flow increase goes higher. The growth rate of heat collecting efficiency reducing with the radiation intensity increase goes higher. The growth rate of heat collecting efficiency growing linearly with the water flow increase goes higher. Cumulative heat collection increases gradually and the growth rate goes lower with the growth of time. The heat collecting efficiency of solar heat collector exponent decreases with the growth of time.Thermal insulation properties:The temperature rise of indoor air reduces 0.5℃～0.8℃ lower and the internal energy increment of indoor air reduces 0.64kJ/m3～1.04kJ/m3 when collector is working under structural pattern 1. The temperature rise of indoor air reduces 0.5℃～1.0℃ lower and the internal energy increment of indoor air reduces 0.65kJ/m3～1.30 kJ/m3 when collector is working under structural pattern 2. The temperature rise of indoor air reduces 1.0℃～1.5℃ lower and the internal energy increment of indoor air reduces 0.81kJ/m3～2.07 kJ/m3 when collector is working under structural pattern 3.The internal energy increment of indoor air grows linearly with the increase of the radiation intensity and reduces linearly with the increase of water flow under three structural patterns. Heat insulation properties of the solar heat collector goes worse after surface color of sunshading plate is painted black. The temperature rise of indoor air increases an average of 0.5℃ and the internal energy increment increases an average of 26.7%. Replacing MG58 phase-change material by steel scrap, the rising trend of indoor air temperature was more smoothly.