Role of Phase Change Materials Containing Carbonized Rice husks on the Roof-Surface and Indoor Temperatures for Cool Roof System Application

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.

Comprehensive Assessment of Pcm Integrated Roof for Passive Building Design: A Study in Energo-Economics

“…They determined that a 2° inclination angle for the PCM layer yielded optimal results, with reductions in ceiling temperature of up to 2.38°C and daily heat gain reduced by up to 16% compared to non-PCM rooms. Kim et al [42] used PCMs with carbonised rice husks to lower roof surface and interior temperatures. Compared to roofs without PCMs, the combination reduced surface temperature to 74.6°C, with a maximum difference of 11°C.…”

Computational Fluid Dynamics for Cavity Natural Heat Convection: Numerical Analysis and Optimization in Greenhouse Application

“…In addition, various studies natural heat convection has being conducted in both theoretical and application regards, including modified turbulent modeling, computational fluid dynamics (CFD) and simulation, nanomaterial additives for thermal-physical improvement and practical engineering optimization, over recent years [18,19]. Shanmuganathan et al [20] experimented on building energy efficiency coupled with reflective coating under natural heat convection boundary conditions.…”

Nanoencapsulated Lauric Acid with a Poly(methyl methacrylate) Shell for Thermal Energy Storage with Optimum Capacity and Reliability

“…25 It is one of the most mass-produced fatty acids. 25 Thermal energy storage materials (TESMs) with a melting point of 40−45 °C are specifically suitable for the following applications: (1) thermal management (passive cooling) for roofs and walls in areas with summer daytime temperature often over 30 °C (it has been found that the application of TESMs (with a melting point in the range of 40−45 °C) for roof thermal management is significantly (e.g., 1.5−4°C 26 ) more effective on lowering the indoor temperature than the ones with a melting point in the range of 25−30 °C), (2) thermal management of a heat exchanger for greenhouse heating applications, 27 (3) thermal management (heat recovery) of a heat pump, 28 and (4) body and water warmer. 29 Therefore, lauric acid is the target PCM material in this study for creating size-tunable polymer-shelled lauric acid nanocapsules.…”