Conjugate simulation of solar honeycomb receiver for high temperature heat absorption at constant incident heat flux

Conjugate radiation-convection-conduction simulation was conducted for a solar volumetric receiver of silicon carbide honeycomb for high temperature heat absorption at 1,000°C and higher. Simulation was made for three cases of channel cell size: 0.6mm; 1.5mm; 2.9mm. At two levels of incident heat flux 1,400 kW m and 4,200 kW m, air mass flux was changed variously for optimization of working conditions. When the cell size is reduced from d = 2.9 mm to 0.6 mm, the receiver efficiency together with the air temperature at the receiver exit increase at each level of incident heat flux. At 1,400 kW m, the receiver efficiency exceeds 0.8 when the air temperature is as high as 1000°C in the case of the smallest cell size: d = 0.6 mm. At 4,200 kW m , the efficiency surpasses 0.80 when the air temperature is almost 1500°C in the case of d = 0.6 mm. The heat losses from the receiver was analyzed through budget of energy balance equation. It was found that the thermal radiation was attenuated by reduction of channel cell size which resulted in enhancement of the receiver efficiency. The mean temperature at the top edge of the receiver decreased with the reduction of channel size in consistency with the attenuation of thermal radiation. The numerical result demonstrated that the reducing cell size is essential to absorb concentrated solar light at very high temperatures beyond 1000°C and higher.