Spatial temperature distribution and ground thermal storage in the plastic greenhouse: An experimental and modeling study

The precise regulation of the indoor thermal environment in plastic greenhouses is impacted by the spatial distribution of indoor air temperature and soil temperature fluctuations. This study used a scaled-down model to take the preliminary experiment to demonstrate the dynamic spatial temperature variation in a plastic greenhouse. Then, by considering the dynamic change in solar orientation, a transient model of a real-size plastic greenhouse coupling soil and indoor microenvironment was developed, validated, and then applied to investigate the spatial temperature distribution in the plastic greenhouse. In addition, a method for measuring the soil capability for effective thermal conversion was proposed. Results showed that the indoor air temperature varied significantly with height. The temperature difference between the air near the roof surface and the air within the building peaked at 13.3 degrees C at 12:00 and was just 2 degrees C at 9:00. The soil temperature increased, and soil temperature peaks delayed sequentially with the soil depths. The daily fluctuation of soil temperature decreased with increasing soil depth, and the temperature remained stable at the depth of 0.45 m. In addition, with an effective heat conversion rate of 40.3 %, the soil regulated the indoor thermal environment as a heat source. This paper provides a reference for the indoor thermal environment regulation of plastic greenhouses for the purpose of saving energy in agricultural production.