3-D CFD analysis of relative humidity distribution in greenhouse with a fog cooling system and refrigerative dehumidifiers

The distribution of humidity in a greenhouse was studied using three-dimensional (3-D) computational fluid dynamics (CFD). The calculations were validated using experimental data from a single-span greenhouse without plants. Two types of humidity distribution were considered: humidifying using a fog cooling system, and dehumidifying using refrigerative dehumidifiers in addition to a fog cooling system. The simulation errors of RH were 0.1-18.4% with a fog cooling system and 1.1-13.1% with a fog cooling system and refrigerative dehumidifiers at each observation point. Contour maps were obtained from the 3-D CFD simulations to locate any non-uniformity in humidity distribution. The use of refrigerative dehumidifiers reduced the overall difference of humidity between the middle and bottom zones of a greenhouse, but the local distribution of humidity was uneven, especially close to the dehumidifiers. This study suggests that the developed 3-D CFD model can be a useful tool in designing and evaluating greenhouses with various configurations.