Evaluation of direct evaporative cooling system (fan-pad) in greenhouse under different environmental conditions

The cultivation of greenhouse crops is an advance in agricultural production technology that is increasing from temperate to warmer regions. However, greenhouse protects crops in a bad weather condition, but high temperature and humidity in the tropics have a converse effect on a production of crops. Therefore, in these regions, it is necessary to reduce the temperature inside the greenhouse. Since the design of the cooling system is highly dependent on environmental conditions, it is difficult to develop an appropriate system that provides local climate conditions for product growth. Therefore, in this research, the performance of fan-pad cooling system was studied in different climatic conditions. For this purpose, the greenhouse environment was first modeled using TRNSYS software. After verifying the model with experimental results, the system's ability to cool the greenhouse and system performance was evaluated relative to the parameters of air velocity, temperature and humidity ratio. The results showed that in ambient conditions with dry bubble temperature and humidity ratio less than 40˚C and 0.015 kg/kg, direct evaporative cooling system (fan-pad) at an air velocity of 1.25 m/s was a suitable method for cooling the greenhouse and provides suitable conditions for product growth. The cultivation of greenhouse crops is an advance in agricultural production technology that is increasing from temperate to warmer regions. However, greenhouse protects crops in a bad weather condition, but high temperature and humidity in the tropics have a converse effect on a production of crops. Therefore, in these regions, it is necessary to reduce the temperature inside the greenhouse. Since the design of the cooling system is highly dependent on environmental conditions, it is difficult to develop an appropriate system that provides local climate conditions for product growth. Therefore, in this research, the performance of fan-pad cooling system was studied in different climatic conditions. For this purpose, the greenhouse environment was first modeled using TRNSYS software. After verifying the model with experimental results, the system's ability to cool the greenhouse and system performance was evaluated relative to the parameters of air velocity, temperature and humidity ratio. The results showed that in ambient conditions with dry bubble temperature and humidity ratio less than 40˚C and 0.015 kg/kg, direct evaporative cooling system (fan-pad) at an air velocity of 1.25 m/s was a suitable method for cooling the greenhouse and provides suitable conditions for product growth. Also, the results showed that in the case of moisture content greater than 0.015 kg/kg, the evaporative cooling system alone could not cool the greenhouse.