Performance improvement of a passive solar still in a water desalination

International Journal of Environmental Science and Technology, Feb 2017

Using a solar energy in water desalination system is regarded as one of the most effective ways to resolve the problem of freshwater shortages in this world. Experimental and theoretical approaches were carried out to design and test multistage solar still. The experimental tests were conducted for five months in the city of Kirkuk, north of Iraq, at 43.39° longitudinal and 35.17° latitude. The performance requirement of the design is dependent on many factors such as circumstances, work and designation variables. Designating variables, mainly length, width, height and volume of each stage besides the number of all stages, are determined via theoretical analysis approach. The results obtained by both approaches have shown that there is a 10% deviation in still water productivity. Also, the results indicated that the minimum and maximum daily average of still water productivity is 1.7 and 3.8 kg. MATLAB software was employed to model and simulate the experimental processes of evaporation and condensation. The simulation model results were found to agree well with the experiments carried out in many other papers and studies. The test results reported that the system produces about 5 kg of clean water per day with 87% distillation efficiency and 26% of the overall efficiency due to heat losses in the system. Such system is not only promising, but can offer a new technology that can particularly be used in remote and rural areas. The theoretical calculations were compared with the experimental results, and there is a good agreement between the two .

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Performance improvement of a passive solar still in a water desalination

Performance improvement of a passive solar still in a water desalination F. M. Abed 0 1 2 M. S. Kassim 0 1 2 M. R. Rahi 0 1 2 0 Department of Mechanical Engineering, Tikrit University , Tikrit , Iraq 1 Editorial responsibility: Mohamed Fathy Yassin 2 Department of Mechanical Engineering, AL-Mustansiriyah University , Baghdad , Iraq Using a solar energy in water desalination system is regarded as one of the most effective ways to resolve the problem of freshwater shortages in this world. Experimental and theoretical approaches were carried out to design and test multistage solar still. The experimental tests were conducted for five months in the city of Kirkuk, north of Iraq, at 43.39 longitudinal and 35.17 latitude. The performance requirement of the design is dependent on many factors such as circumstances, work and designation variables. Designating variables, mainly length, width, height and volume of each stage besides the number of all stages, are determined via theoretical analysis approach. The results obtained by both approaches have shown that there is a 10% deviation in still water productivity. Also, the results indicated that the minimum and maximum daily average of still water productivity is 1.7 and 3.8 kg. MATLAB software was employed to model and simulate the experimental processes of evaporation and condensation. The simulation model results were found to agree well with the experiments carried out in many other papers and studies. The test results reported that the system produces about 5 kg of clean water per day with 87% distillation efficiency and 26% of the overall efficiency due to heat losses in the system. Such system is not only promising, but can offer a new technology that can particularly be used in remote and rural areas. The theoretical calculations were compared with the experimental results, and there is a good agreement between the two . Solar still; Multistage parabolic type; Distilled water; Solar collector - Shortage of freshwaters is considered one of the most serious environmental problems facing today’s world. Most of the water available on earth is highly salty sea and ocean waters, which is not suitable for drinking. Thus, the world has no choice but to desalinate sea and ocean waters efficiently at low cost. Solar distillation process appears to be suitable to resolve this problem through purification of salty water. Distillation process uses solar radiation, which is a form of thermal energy produced by a multistage solar still connected to a parabolic trough collector to improve its performance and to increase production of distilled drinking water. Solar distillation uses simple device called solar distillates in a process similar to the natural evaporation of water by sun heat. Solar distillates are classified into two main types: positive still and active solar still which adds a number of external components such as concentrates or solar collectors. Also, it includes two types with multiple distillates that involving single and multiple basins. Basins are of many types with oblique cover, two way cover, ring cover and cone cover in addition to vertical distillates. ALKaraghouli and ALnaser (2004) conducted an experimental study on two stills, one with single basin and the other with double basin. Both have the same internal basin area (0.45 m2) with internal dimensions of 50 9 90 cm for each still. The study was conducted based on two types of stills, one a solar still with thermally insulated walls on both sides and the other without insulated walls. A glass double basin cover is tilted at 12 angle horizontally while the single basin cover is tilted at 36 angle horizontally as well. Tests were out on the two stills for the period from February to June. Results showed that the highest average daily production of distilled water is in June for both types due to high solar radiation rate in June, and the average production of distilled water by the isolated still is higher than those obtained without isolation. Results also showed that the daily production rate of water in the double basin still was higher than single basin still by 40% with the same operation conditions. Attaseth et al. (1985) have manufactured two vertical identical stills to study the effect of different lids made of glass and plastic on productivity rate. Based on the same experimental operating conditions in terms of operational system, design and weather conditions thus showed that the productivity of distilled water with a glass cover is higher than the using plastic cover by 10%. Akash et al. (2000) studied the effect of using five different angles of inclination a transparent cover (55 , 45 , 35 , 25 , 15 ) on the solar distilled productivity. The study was conducted in Jordan at different operating conditions. Results have shown that 35 Æ angle inclination is the best for the production of distilled water. Nijmeh et al. (2005) conducted a theoretical and experimental study throu (...truncated)


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F. M. Abed, M. S. Kassim, M. R. Rahi. Performance improvement of a passive solar still in a water desalination, International Journal of Environmental Science and Technology, 2017, pp. 1277-1284, Volume 14, Issue 6, DOI: 10.1007/s13762-016-1231-9