Study on thermal property of a solar collector applied to solar greenhouse

The problem of low indoor ambient temperatures during the cold season has been a restrictive factor affecting the excellent quality and high yield of plants in solar greenhouses. In this study, a building -integrated, efficient and aesthetical solar collector applicable to heating the solar greenhouse was described. To study the thermal property of the solar collector, a three-dimensional Computational Fluid Dynamics model of the solar collector was proposed. The accuracy of the model was verified through a field test on a solar water heating system equipped with solar collectors. The results indicate that the developed model can predict the thermal property of the solar collector with acceptable accuracy. Increasing solar irradiance, enhancing collector water flow velocity, raising indoor ambient temperature, and decreasing inlet water temperature are beneficial for improving the thermal property of the solar collector. The solar water heating system can collect surplus heat during the daytime for nighttime heating. With an inlet water temperature below 13.8 degrees C, the heat collection efficiency was above 100%. Increasing the collector water flow velocity from 0.4 to 0.6 cm/s resulted in an enhancement of the heat collection efficiency by less than 2%. The solar water heating system can improve the indoor temperature environment, with the indoor ambient temperature raising by an average of 3.2 degrees C. Furthermore, the solar water heating system is an assembled system that is suited for various greenhouses. Through the analysis of thermal property and economy that the heating system has significant prospects of promotion.