Thermal Performance of Air Receiver Filled with Porous Material for 5KWt Dish Solar Collector

초록

The thermal Performance of a volumetric air receiver filled with porous material for 5kWt dish solar thermal system installed in Inha University, Korea, is experimentally investigated. The diameter of the parabolic dish is 3.2 m, and its focal length is 2m. It consists of 10 small pieces of glass which have their own curvatures, and the effective reflecting area is 5.9 m2. The reflectivity of the glass is 0.95, and the rim angle of the dish is 43.85°. The thermal capacity of the system is about 5 kW thermal. The aperture diameter of the cylindrical-shape receiver which is made of stainless steel is 100 mm, and the height is 210mm. A quartz window is installed at the receiver aperture to minimize the convective heat loss and prevent air leakage. In order to increase the heat transfer area, porous material (nickel-alloy) is inserted into the receiver. Experiments are being carried out to investigate the thermal performance variation of the receivers with several design parameters such as the shape of the receiver, the volume and the shape of the porous material, the flow directions and the flow rate of air, etc. In the present paper, the relation between the thermal efficiency and the air flow rate is shown as the first step of the work. Air flows into the upper part of the receiver, which is the opposite side of the aperture. After the air flows through the inside receiver, it goes out of the receiver through 3 exits which are located near the aperture. The results show that the system efficiency and receiver efficiency increase as the volume flow rate increases as expected.