Enhancement of droplets quality for fog cooling system in a naturally-ventilated greenhouse using centrifugal and axial fans

Abstract

A fog cooling system (FCS) is applied to maintain the desired air temperature and humidity in a greenhouse. For the effective application of this system, sizes of fog particles belonging to the criteria of less than 60 μm in diameter and its uniformity are important parameters that need to be achieved. The objective of this research is to analyze usage of centrifugal and axial fans in order to enhance quality of fog particles that generated through 0.1-mm nozzles. Horizontally installed nozzles with both centrifugal and axial fans to create finer and more uniform fog particles was compared with horizontal nozzles with centrifugal fans only and with axial fans only. The centrifugal fans are installed 80 cm in front of nozzles while the axial fans are installed behind nozzles. The sizes of fog particles resulted by centrifugal fan, axial fan, and both axial and centrifugal fans are 11.90 μm 5.280 μm and 2.69 μm respectively. The use of both fans produces the most delicate fog particles. Electricity consumption for both fans is the smallest compare to the other electrical appliances on FCS (relay, pump, pressure release valve). Additional electricity power consumption per hour due to the use of both fans is 25 W.