الملخص الإنجليزي
Prolonged aridity in the Sultanate has resulted in freshwater deficit in some parts of the country. In coastal areas, the aridity coupled with overpumping of groundwater have often resulted in seawater intrusion. Looking for alternatives to provide freshwater for domestic, industrial and agricultural purposes is an ultimate goal for the government. An overview of these alternatives is described in this study. The use of solar radiation in greenhouses to desalinate saline/brackish water was proposed as an alternative to provide freshwater for irrigation. This study aims at constructing and preliminary testing a humidification-dehumidification system in a Quonset greenhouse for producing freshwater. The greenhouse was constructed and tested at the Agricultural Experiment Station (AES) of Sultan Qaboos University.
This greenhouse was modified to work with two humidifiers (i.e., evaporating pads), to increase water vapor inside the greenhouse as much as possible, and two dehumidifiers (i.e., condensers) to condense this water vapor. After evaporation, water leaving the humidifiers was cooler than the incoming water. This cooled water was pumped to the two dehumidifiers and acted as a coolant.
Preliminary testing of the performance of the greenhouse showed an increase in the amount of water vapor after the second humidifier. The temperature of the dehumidifiers was always lower than the dew-point temperature of the air passing through them. This meant that there was a potential for condensation. However, condensation was insufficient to result in a measurable quantity.
Possible reasons for this insufficient condensation were investigated. Finally, recommendations for improvements of the humidifiers and dehumidifiers were suggested.
