Development of a Humidification–Dehumidification System in a Quonset Greenhouse for Sustainable Crop Production in Arid Regions

This paper presents a pilot design for a humidification–dehumidification system in a Quonset greenhouse. The objective of this study was to investigate the potential of saline/brackish water evaporation and freshwater condensation to provide an alternative source of freshwater for irrigation in a greenhouse. Two humidifiers, each comprising a wall of evaporative cooling pads were used to increase water vapour inside the greenhouse as much as possible; and two dehumidifiers (i.e. condensers) condensed the water vapour. Preliminary testing of the performance of the greenhouse showed an increase in water vapour close to saturation after the second wall of cooling pads. The temperature of the water flowing in the dehumidifiers was always lower than the dew-point temperature of the air passing through them. Hence, condensation could occur and was observed on the dehumidifier. However, condensation was insufficient to result in a measurable quantity. Recommendations for design improvements of condenser are suggested.