IMPROVEMENT OF EVAPORATIVE COOLING SYSTEM EFFICIENCY IN GREENHOUSES

Abstract

An assisted evaporative cooling system is proposed and analyzed to get higher cooling efficiency in hot and arid environments such as Saudi Arabia. For this purpose, a two-stage evaporative cooling experimental setup consisting of a direct evaporative cooling and indirect evaporative cooling was designed, constructed, and tested.

The obtained data showed that, the hourly average solar radiation flux incident outside and transmitted into the greenhouse was 555.7 and 298.7 W/m², respectively, consequently, the effective transmittance of the covering material was on the average 53.75%.  The temperature and relative humidity of outdoor air, respectively, were 37.3ºC and 21.8%, dry and wet-bulb temperatures just leaving the cooling coil were 29.4ºC and 18.8ºC, respectively, and dry-bulb temperatures of air just leaving the direct evaporative cooling were 22.8ºC. The obtained results also revealed that, the overall effectiveness of the combining cooling system was more than 100%. Thus, this system environmentally clean and energy efficient system, which considered as an alternative to the mechanical, vapour compression systems. It can also conclude that, this combining cooling system can use in various climatic conditions as an environmentally clean and energy efficient system.