Wind turbine-inclined still collector integration with solar still for brackish water desalination Mohamed A. Eltawil a,b, ⁎, Zhao Zhengming a a The State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing, 100084, China b Agricultural Engineering Department, Kafrelsheikh University, Box 33516, Egypt abstract article info Article history: Received 11 December 2007 Accepted 19 June 2008 Available online 4 October 2009 Keywords: Wind turbine Solar stills Water desalination Hot water Water quality This paper presents a new hybrid desalination system that constitutes of wind turbine (WT) and inclined solar water distillation (ISWD) integrated with main solar still (MSS). The new developed system is designed, fabricated and evaluated under actual environmental conditions. A small wind turbine is used to operate a rotating shaft fitted in the MSS to break boundary layer of the basin water surface. Also, an ISWD system which consists of an inclined flat solar absorber plate covered with black-wick medium is attached to the exit of MSS. The system can produce distilled and hot water. The heating and evaporating processes take place in MSS as well as ISWD, and then the water are condensing on the glass covers. The system was tested at different water depths (0.01, 0.02 and 0.03 m), different water flow rates (25.0, 41.7 and 58.3 ml/min) and two modes of operation as due south and tracking the sun. Variation of ambient conditions, and water temperatures and outputs were used to evaluate each parameter. It was found that, increasing water depths at the same flow rate caused a decrease in the distilled water productivity. The amount of fresh water per square meter from the ISWD could be higher than the MSS with a range of 26.55 to 29.17% when the system is due south, while it ranged from 27.1 to 32.93% when the system is tracking the sun. The average daily efficiency of MSS and ISWD ranged from 67.21 to 69.59 and 57.77 to 62.01% when the system was due south, while it ranged from 66.81 to 69.01 and 57.08 to 62.38% when the system was tracking the sun, respectively. The water product cost is found to be 0.662 and 0.552 RMB/l (1 US $ = 7.43 RMB) when the system was due south and tracking the sun, respectively. The electricity annual savings is found to be 195.22 RMB/kWh/m 2 . The distilled water quality as well as hot remaining water is good enough for domestic usage. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Large quantities of fresh water are required in many parts of the world for agricultural, industrial and domestic uses. A very small fraction, about 0.3%, of the available water resources is available as fresh water [1]. In the arid areas of the world, small and remote communities have critical problems associated with providing safe water supplies. Specific water quality problems include salinity, iron, manganese, fluoride, heavy metals, bacterial contamination, and pesticide/herbicide residues [2]. Lack of fresh water is a prime factor in inhibiting regional economic development. A chronic drinking water shortage is one of the most important issues in the developing countries, and drinking water from dirty water sources causes serious damage to health. Desalination processes consume significant amounts of energy, and many countries in the world, particularly those suffering from severe water shortages, cannot afford the energy required for desalination. Fortunately, many of those countries lie in areas with high insolation rates. Therefore, solar distillation of water can be a practical alternative which offers life to those regions where the lack of fresh water hinders development. Solar energy can be used to produce fresh water directly in a solar still or indirectly where the thermal energy from a solar energy system is supplied to a desalination unit. It has been shown that solar distillation remains the most favourable process for the sup- plying of water to small communities. Renewable energies are expected to have a flourishing future and an important role in the domain of brackish and seawater desalination in remote areas. Conventional technologies to treat water supply systems consist of simple settling, disinfection with chlorine or iodine, reverse osmosis water systems or ion exchange water softeners. Simple disinfection reduces harmful bacteria, but does not reduce salinity or remove heavy metals. Several types of solar stills exist, the simplest of which is the single- basin type. Solar stills could, however, be considered attractive for domestic purposes, especially in areas having no access to the electric grid and low labor cost. An improved version with enhanced efficiency needs more complex constructional, operational and maintenance Desalination 249 (2009) 490–497 ⁎ Corresponding author. The State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing, 100084, China. Tel.: +86 10 62773237; fax: +86 10 6279415. E-mail address: eltawil69@yahoo.co.in (M.A. Eltawil). 0011-9164/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2008.06.029 Contents lists available at ScienceDirect Desalination journal homepage: www.elsevier.com/locate/desal