Research on creating the indoor thermal environment of the solar greenhouse based on the solar thermal storage and release characteristics of its north wall

Improving the solar thermal storage capacity of the north wall of the solar greenhouse can effectively enhance the indoor thermal environment during the night-time in winter. However, the indoor thermal environment is also influenced by the interaction between the spatial parameters of the solar greenhouse and outdoor meteorological conditions. Additionally, the heat storage and release performance of the north wall are dynamically affected by changes in the indoor thermal environment. This complicates the quantitative assessment of the impact of solar active–passive heat storage methods applied to north walls on the indoor thermal environment. Therefore, in this study, we develop a mathematical model that considers simplified calculations of the solar greenhouse's spatial parameters and the design method of an active–passive ventilation wall with latent heat storage, which was proposed in the early stage, for evaluating the impact of the solar thermal storage and release characteristics of the north wall on the indoor thermal environment of the solar greenhouse. This model is validated against measured data from the experimental solar greenhouse with high accuracy. Using this model, we analyze the quantitative reinforcement effects of a phase change composite wallboard and a solar collector system on the solar energy utilization of the north walls and its effects on the indoor thermal environment. Compared to ordinary solar greenhouses in Wuzhong, the application of a GH-20 composite phase change thermal storage wallboard to improve the passive solar energy utilization of the north wall can increase the solar energy contribution rate by 90.9%. Furthermore, integrating a multi-surface solar air collector with double-receiver tubes on the phase change composite wall can increase the solar energy contribution rate by 95.4%. Also, the experimental results reveal that the solar active–passive heat storage methods applied to the north wall can enhance the indoor thermal environment during night-time and increase cucumber yield by more than 10% in winter. This study provides a method reference for optimizing the active–passive solar thermal utilization of the solar greenhouse.