The effect of a fogging system on sensible and latent heat transfer in a rose greenhouse

The objectives of this study were to: evaluate the effects of a fogging system on sensible and latent heat transfer in a rose greenhouse, determine the efficiency of the fogging system, and investigate the cooling and humidifying effects of the fogging system in a plastic greenhouse. Bowen ratio (ß) was also calculated based on the rates of sensible and latent heat transfer. The ß can be used as an indicator of the conditions existing within the plant canopy in the greenhouses, The ß provided a means of estimating components of the energy balance of the plant environment. The experiments were carried out in a multi-span plastic greenhouse 105.6 m wide and 205 m long with 11 spans. The fogging system consisted of: a water softener and filters to prevent nozzle clogging, a water reservoir, pumps and a pressure regulator, and the fog generating nozzles. Three nozzle lines with 82 fog-generating nozzles were installed in each span of the plastic greenhouse. The results showed that the fogging system was able to keep the air temperature inside the PG 6.6°C lower than the outside. The air relative humidity inside the plasticgreenhouse was increased by 25% by means of the fogging system examined in this study. The results obtained from this experimental work showed that the greatest efficiency of the FS was 80%. The rate of sensible heat transfer varied from 6.9 W/m 2 to 476.5 W/m2, while the rate of the latent heat transfer changed between -87.9 W/m2 and -825.8 W/m2 in the plastic greenhouse. The ß ranged from -0.07 to -0.72 during the experimental period. The values of ß indicated that the sensible heat transfer occurred in a direction toward the plant canopy while the latent heat transferred away from it