Abstract
This study researches the effect of phase change materials (PCMs) containing carbonized rice husks (CRHs) in wood plastic composites (WPCs) as roof finishing materials on roof-surface and indoor temperatures. A cool roof miniature model was prepared, and measurements were taken using three fixed temperatures of 30 to 32 °C, 35 to 37 °C, and 40 to 42 °C. Sodium sulfate decahydrate (Na2SO4·10H2O) and paraffin wax were selected as the PCMs. CRHs were used as additives to improve the thermal conductivities of the PCMs. At lower fixed temperatures such as 30 to 32 °C and 35 to 37 °C, the rates of increase of the surface temperatures of roofs containing CRHs with Na2SO4·10H2O, and paraffin wax, were observed to gradually decrease compared to those of the roofs without PCMs. The indoor temperatures for the above-mentioned PCMs containing CRHs were maintained to be lower than those of the indoors without PCMs. Additionally, as the CRH content in the PCM increased, the rates of increase of the roof-surface and indoor temperatures decreased due to a faster roof heat absorption by PCMs through the improved thermal conductivity of CRHs. However, under higher artificial temperatures such as 40 to 42 °C, Na2SO4·10H2O with CRHs exhibited no effect due to being out of latent heat range of Na2SO4·H2O. For paraffin wax, as CRH content increased, their roof- surface and indoor temperatures decreased. Especially, the surface temperature of the roof containing paraffin contained 5 wt.% CRHs reduced by 11 °C, and its indoor temperature dropped to 26.4 °C. The thermal conductivity of PCM was enhanced by the addition of CRHs. A suitable PCM selection in each location can result in the reduction of the roof-surface and indoor temperatures.
Highlights
Direct exposure of construction surfaces to sunlight has been observed to increase the temperature in buildings; this is because of the higher heat storage and lower heat emission of materials such as concrete or metal deck [1–6]
phase change materials (PCMs) used for cool roof system applications are materials capable of absorbing or releasing thermal energy in the form of latent heat during the solid–liquid transition, and are extensively economy areas duedue to sustained heat source temperature, high energy applied in inmany manyenergy energy economy areas to sustained heat source temperature, high density, energy and repeated utilizationutilization
The aim of this study was to research the attainment of reduced roof-surface and indoor temperatures through fast roof heat absorption by improving the thermal conductivity of PCMs the addition additionofofCRHs
Summary
Direct exposure of construction surfaces to sunlight has been observed to increase the temperature in buildings; this is because of the higher heat storage and lower heat emission of materials such as concrete or metal deck [1–6]. Convex husks can energy storage capability by acapability simple impregnation method and increase heat maximize the energy storage by a simple impregnation method the andspecific increasearea the for specific transfer in PCMs. area for heat transfer in PCMs. The aim of this study was to research the attainment of reduced roof-surface and indoor temperatures through fast roof heat absorption by improving the thermal conductivity of PCMs the addition additionofofCRHs. CRHs.InIn addition, study aimed to minimize the energy in latent through the addition, thethe study aimed to minimize the energy loss loss in latent heat heat storage retrieval progress removing phase segregationthat thatisisnot not completely completely soluble storage and and retrieval progress by by removing thethe phase segregation during melting and the supercooling problems that remain molten PCMs during crystallization to ensure timely release of the heat of fusion. To apply the cool roof system, a cool roof miniature model was prepared
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