Numerical Analysis of the Effect of Ground Dampness on Heat Transfer between Greenhouse and Ground

Abstract

This paper deals with the problem of the influence of ground dampness on heat exchange between greenhouse and ground. The effect of humidity on the distribution of ground temperature fields was analyzed. The analysis was performed based on the analytical numerical method in the WUFI®plus software. The computational tool was used after a validation process. Research and simulations were conducted on the example of a real single-span greenhouse located in Southern Poland. The results of indoor and outdoor air temperature measurements were used to determine the boundary conditions, while the measured ground temperatures were used to compare with the results of theoretical calculations. Three variants were used for calculation analysis, assuming different levels of ground dampness. Analysis of the test results showed that during the summer period, dry ground provides 8% more thermal energy to the interior of the greenhouse than the damp ground, and provides 30% more thermal energy than wet ground. In the transition period (autumn/spring), the ground temperature fields are arranged parallel to the floor level, while the heat flux is directed from the ground to the interior of the greenhouse, regardless of the ground dampness level. During this period, the ground temperature ranges from 4.0 °C to 13.0 °C. Beneficial effect of dry ground, which contributes to maintaining an almost constant temperature under the greenhouse floor, was found in winter.