Thermal Performance Comparisons of Glass Evacuated Solar Collectors Usng Different Absorbing Tubes

초록

The thermal performance of a glass evacuated tube solar collector is numerically investigated. The solar collector considerer in this paper consists of a two-layered glass tube and an absorber tube that has fins. The air is used as a working fluid. The length and the diameter of this glass tube are 1,200mm and 37mm, respectively. In this paper, four different shapes of absorber tubes are considered, and the performance of each solar collector is compared to find the best shape of the absorber tube for the solar collector performance. From the calculation, it is known that the performance of the solar collector is a strong function of the incidence angle of solar radiation and absorber tube’s shape. The result shows that the thermal performance of the plate fin absorbers and rectangular duct fin absorber is sensitive to the incidence angle of solar irradiation. On the other hand, the thermal performance of the circular fin absorber is independent of the incidence angle. However, the effect of the diffuse radiation and the shadow due to the neighbor tubes are not considered in this paper. So, these effects will be investigated for more accurate results