Numerical Study on Thermal Efficiency of Large-Scale Flat-Plate Solar Collectors

The flat-plate solar collectors have better efficiency characteristics in low-temperature region. With the development of solar thermal utilization technology, the research of collectors suitable for different temperature requirements, application sites and personalized design of collectors will be a new direction in the future, and the flat-plate solar collectors used in solar heating system will be a development trend. Therefore, it is proposed that the flat-plate solar collectors should increase their collector efficiency and outlet temperature by increasing the scale. According to the heat transfer mathematical model of flat-plate solar collector, the relationship between heat-collecting area and collector efficiency was studied. In this paper, the 3-D physical models of the large-scale flat-plate solar collectors were established. The CFD software was used to simulate the operation characteristics of large-scale flat-plate solar collectors under different working conditions, and the heat loss, heat collection and thermal efficiency of different scale collectors were analyzed. It is shown that the instantaneous efficiency of large-scale collector is 1– 4% higher than that of parallel collector.