Enhancement of evaporative cooling system in a greenhouse using geothermal energy

In desert climates cooling greenhouses are needed to protect crops from extremely high temperature. In Iraq, outside air temperature can reach 50 degrees C during the summer, which makes greenhouses unworkable in this season. So, this work was trying to overcome this situation and to examine the feasibility of greenhouse cooling using groundwater in the indirect-direct evaporative cooling (IDEC) unit. For this purpose, a two-stage evaporative cooling experimental setup consists of one indirect evaporative cooling heat exchanger and three pads as a direct evaporative cooling designed, constructed, and analyzed. A series of experimental tests were carried out in June, July, and August 2015 during the summer of Baghdad with different parameters. The results show that the use of groundwater enhanced IDEC unit efficiency up to 108% compared with a direct evaporative cooling efficiency that recorded 77.5%. Using covering layers reduced the intensity of solar entering the greenhouse from 15% for a single layer to 40% in the case of two layers with one layer of green mesh. The IDEC system using groundwater gives decreasing in the greenhouse temperature by about 12.1 degrees C -21.6 degrees C and increasing relative humidity from 8% to 62% compared with the ambient conditions. (C) 2017 Elsevier Ltd. All rights reserved.