3D numerical modelling and experimental validation of an asphalt solar collector

Abstract

Research about renewable technologies for thermal energy collection is crucial when critical problems such as climate change, global warming or environmental pollution are concerned. Transforming solar energy into thermal energy by means of asphalt solar collectors might help to reduce greenhouse gas emissions and fossil fuel consumption. In this paper, a laboratory-scale asphalt solar collector formed by different slabs has been characterized by applying numerical techniques. An experimental test where the thermal performance of the collector was determined for three values of heat exchange fluid flow rate was carried out for the validation of the numerical model. Then, the CFD model was used to analyse the thermal response of the collector according to the following parameters: flow rate, solar irradiance, size and thickness. Results show that increasing values of heat exchange fluid flow rate result in better thermal performances. Likewise, increasing values of irradiance and size of the collector lead to higher values of thermal performance, although other parameters should also be considered for the final design of the system. Finally, under the conditions here considered, the thickness of the collector turned out not to be as significant as expected in relation to its thermal response. The combination of experimental tests and CFD codes can be considered a powerful tool for the characterization of asphalt solar collectors without incurring significant costs related to experimental field tests.

Evaluation of Stone Mastic Asphalt Containing Ceramic Waste Aggregate for Cooling Asphalt Pavement

“…Once the heat flux density at the boundary of the pavement structure is prescribed, the thermodynamic boundary condition can be regarded as the second type, namely the Neumann condition, which is defined as: where n x , n y , and n z are direction cosines of the outward normal to the pavement surfaces, respectively, and (t) is the prescribed heat flux density at the pavement structure boundary (W/m 2 ). As for asphalt pavement exposed to the outdoor environment, the heat flux density (t) at the pavement surface includes solar radiation q s , convection heat transfer q c , and thermal irradiation q r [ 43 ], as presented in Figure 6 .…”

“…While absorbing the radiation emitted from the environment, the asphalt pavement also radiates energy in the form of long-wave radiation. According to the Stefan–Boltzmann law [ 43 ], the thermal irradiation q r between the pavement surface and adjacent air can be defined by using the following formula: where e is the emissivity coefficient of the asphalt pavement surface, here e = 0.81; C s is the Stefan–Boltzmann constant, C s = 5.6697 × 10 −8 W m −2 K −4 ; and T * is the absolute zero degree, T * = −273 °C.…”

Direito De Acesso À Coleta Seletiva E O Descumprimentro Das Metas Pelo Município De São Paulo

“…Quando se busca a redução da temperatura de pavimento taxas de fluxo mais altas reduzem com mais eficiência a temperatura do pavimento, no entanto, quando se busca uma maior eficiência no aquecimento de fluido, menores taxas de fluxo conseguem absorver mais energia (ALONSO-ESTÉBANEZ et al, 2017;GAO et al, 2010;SHAOPENG;MINGYU;JIZHE, 2011).…”

Energy harvesting from pavements and roadways: A comprehensive review of technologies, materials, and challenges

“…Alonso‐Estébanez et al presented numerical modeling and experimental validation of a laboratory scale ASC, to study the effects of flow rate, solar irradiance, size, and thickness. It was found that increase of flow rate, irradiance, and size increased the thermal performance of ASC, while the impact of thickness was relatively insignificant.…”