Study on soil temperature distribution and cold/heat zoning method of solar greenhouse based on thermal superposition principle

Solar greenhouse can be realized in the winter counter-season production, soil temperature is to ensure that the normal growth of crops is one of the key factors. Grasp the solar greenhouse soil heat transfer characteristics and its temperature change law, the solar greenhouse thermal environment effectively create an important significance. This study intends to start from the greenhouse soil temperature distribution characteristics, based on the principle of heat transfer superposition, combined with a large number of measured results, analyzes the soil temperature along the greenhouse span. Further, combining with the geometric characteristics of solar greenhouse and plant growth law, this study proposes a mechanism for optimizing the winter thermal environment of large-span solar greenhouses and its design method for mechanized operation. The research results show that, influenced by the special structure, the soil temperature of the greenhouse presents the distribution law of low south and high north, which directly leads to the poor growth of crops in the south side. The mathematical model of soil temperature effectively reflects the dynamic change law of soil temperature, and the measured results verify the validity of the model. The concept of cold/heat zoning of solar greenhouse and its design method proposed in this study are scientific and feasible. In winter, compared with the control solar greenhouse, the indoor air and soil temperature of the new greenhouse increased by 1.11 °C and 0.36 °C, the energy consumption for active heating is reduced by 2889.92 MJ, the construction space increased by 27.3 %, and the land utilization rate increased by 9.5 %. The result of this study provides new concepts and methods for the scientific design of solar greenhouse.