Greenhouse; Solar energy; Shading; Evaporative cooling; Thermal modeling
A mathematical model through flowing water film on shade cloth, stretched over the roofs and south wall of an even span greenhouse has been developed to study the effectiveness of cooling in greenhouse. The model was validated experimentally for the climate of Delhi during summer period, out of the data collected in the experiments conducted under three conditions, i.e. shaded with water flow, shaded and unshaded conditions of greenhouse. Parametric studies involving the effects of flow rate of water, length of roof, relative humidity of ambient air and absorptivity of shading material on the cooling performance of greenhouse room air temperature have been made with the help of the model. From the results it was found that the room air temperature was reduced by 6 and 2 °C in shaded with water flow and shaded conditions, respectively, as compared to unshaded conditions. Also the predicted room air temperatures were in fair agreement with the experimental values.