Theoretical Study of the Aspect Ratio of a Solar Still with Double Slopes

A. Madhlopa
Energy Systems Research Unit, University of Strathclyde, James Weir Building, Glasgow, United Kingdom

J. A. Clarke
Energy Systems Research Unit, University of Strathclyde, James Weir Building, Glasgow, United Kingdom

Ladda ner artikelhttp://dx.doi.org/10.3384/ecp110573873

Ingår i: World Renewable Energy Congress - Sweden; 8-13 May; 2011; Linköping; Sweden

Linköping Electronic Conference Proceedings 57:27, s. 3873-3880

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Publicerad: 2011-11-03

ISBN: 978-91-7393-070-3

ISSN: 1650-3686 (tryckt), 1650-3740 (online)


Clean water is essential for good health which influences the social and economic development of any nation. However; there is limited access to safe water on a global scale. This challenge can be overcome through a multi-faceted approach; including the development of appropriate technologies for water treatment and decision-making tools. Solar distillation is one of the commonest non-conventional methods for improving the quality of water. In this vein; the most widely-exploited solar distillation system is a conventional solar still; which has a thin layer of saline water in a shallow basin with a transparent cover over the water and one or two slopes. The productivity of a solar distillation system is influenced by design; climatic and operational factors; with solar radiation being the most influential meteorological parameter. It is therefore necessary to optimize solar radiation that effectively reaches the base of the solar still. Previous attempts have sought to improve the design characteristics of conventional solar stills through the consideration of system geometry and optical properties of construction materials. One of the important geometric parameters is the ratio (R) of length to width (aspect ratio) of the still base. For a single-slope solar still (SSS); R has been examined in preceding studies. Nevertheless; there is a paucity of information on the aspect ratio of a double-slope solar still. In this study; a state-of-the-art software (ESP-r) was used to simulate the variation of effective insolation with R for a double-slope solar still (DSS) in the east-west and north-south orientations and a SSS facing south. Meteorological data captured at the University of Strathclyde (55o 52' N; 4o 15' W) and Guantanamo Bay (19o 54' N; 14o 51' E) was employed in this analysis. Simulation results show that the optical performance of a DSS was lower (in both orientations) than that of a SSS at both sites. The DSS collected more solar energy in the eastwest than north-south orientation; for a given value of R. In addition; effective insolation increased with R to an optimum level for both the DSS and SSS. Approximate optimum values of R were 3.0 and 2.0 for the University of Strathclyde and Guantanamo Bay respectively. However; the optimum value of R was not sensitive to the orientation of the DSS at the two sites. Further; the DSS and SSS exhibited the same optimal value of R at a specific site. It appears that R significantly affects solar collection in a DSS.


Aspect ratio; Effective insolation


[1] G.N. Tiwari; H.N. Singh; R. Tripathi; Present status of solar distillation; Solar Energy 75; 2003; pp.367-373. doi: 10.1016/j.solener.2003.07.005.

[2] WHO; World Health Statistics 2008; World Health Organization; 2008.

[3] H.P. Garg; H.S. Mann; Effect of climatic; operational and design parameters on the year round performance of single-sloped and double-sloped solar still; under Indian arid zone conditions. Solar Energy 18; 1976; pp.159-164. doi: 10.1016/0038-092X(76)90052-9.

[4] A.S. Nafey; M. Abdelkader; A. Abdelmotalip; A.A. Mabrouk; Parameters affecting solar still productivity. Energy Conversion and Management 41; 2000; pp.1797-1809. doi: 10.1016/S0196-8904(99)00188-0.

[5] K. Mukherjee; G.N. Tiwari; Economic analysis of various designs of. conventional solar stills. Energy Conversion and Management 26; 1986; pp.155-157. doi: 10.1016/0196-8904(86)90049-X.

[6] B.W. Tleimat; E.D. Howe. Comparison of plastic and glass condensing covers for solar stills. Solar Energy 12; 1969; pp.293-304. doi: 10.1016/0038-092X(69)90044-9.

[7] H.M. Qiblawey; M. Banat; Solar thermal desalination technologies. Desalination 220; 2008; pp.633-644. doi: 10.1016/j.desal.2007.01.059.

[8] R. Tripathi; G.N. Tiwari; Performance evaluation of solar still by using the concept of solar fraction. Desalination 169; pp.2004; 69-80.

[9] P.I. Cooper; W.R.W. Read; Design philosophy and operating experience for Australian stills. Solar Energy 16; 1974; pp.1-8. doi: 10.1016/0038-092X(74)90037-1.

[10] P.I. Cooper; The absorption of radiation in solar stills; Solar Energy 12; 1969; pp.333-346. doi: 10.1016/0038-092X(69)90047-4.

[11] M.A. Samee; U.K. Mirza; T. Majeed; N. Ahmad. Design and performance of a simple solar still. Renewable and Sustainable Energy Reviews 11; 2007; pp.543-549. doi: 10.1016/j.rser.2005.03.003.

[12] A.K. Singh; G.N. Tiwari; P.B. Sharma; E. Khan; Optimization of orientation for higher yield solar still for a given location; Energy Conversion and Management 36; 1995; pp.175-187. doi: 10.1016/0196-8904(94)00045-2.

[13] V.K. Dwivedi ; G.N. Tiwari; Experimental validation of thermal model of a double slope active solar still under natural circulation mode; Desalination 250; 2010; pp.49-55 doi: 10.1016/j.desal.2009.06.060.

[14] M.E. El-Swify; M.Z. Metias; Performance of double exposure still; Renewable Energy 26; 2002; pp.531-547. doi: 10.1016/S0960-1481(01)00160-4.

[15] J.A. Clarke; Energy simulation in building design; Butterworth-Heinemann; 2nd edition; 2001; pp.212-255.

[16] R. Perez; P. Ineichen; R. Seals; J. Michalsky; R. Stewart; Modelling daylight availability and irradiance components from direct and global irradiance; Solar Energy 44; 1990; pp.271-289. doi: 10.1016/0038-092X(90)90055-H.

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