Experimental investigation and design of a solar desalination unit which work with humidification-dehumidification process

Abstract

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.

Solar desalination is an appropriate method for providing fresh water by using renewable solar energy. Solar desalination with humidification and dehumidification process is one of the most effective methods among solar desalination units. This technique presents several advantages such as flexibility in capacity, moderate installation and operating costs, simplicity, possibility of using low temperature energy (geothermal, solar, recovered energy or cogeneration), etc. Processes that are used in this method are the open water cycle- open air cycle, open water cycle- closed air cycle and closed water cycle- closed air cycle. Process used in this work is a open water-closed air cycle type, in which air is circulated in the unit by forced or natural draft between the humidifier and condenser. In this paper, the different effective parameters such as rate of water flow entering condenser, internal temperature to the humidifier, natural and forced air flow, etc were examined. With the temperature increase of water entering humidifier, the amount of produced steam and, as a result, fresh water was increased. However, for temperature increase of water which exits from collector the mass of salty water inflow should be decreased. This decrease of water flow causes reduction of desalinated water in the condenser section of the unit. Results show that there is an optimum rate of salty water flow entering to the unit. Besides, a considerable difference in production of present work with almost others were observed for natural and forced air flow.