Mathematical modelling and experimental study of a solar distillation system

The production of potable water from saltwater or brackish water using solar distillation has been practised for many years in different parts of the world. However, little attention has been paid to the feasibility of this technique in Iran. In this work, a solar still with a basin area of 0.9 m2 and a glass cover in the form of a pyramid has been designed and constructed, and its performance is studied experimentally in Mashhad, Iran. Also, the performance of the solar still is modelled where a small fan was utilized to enhance the daily productivity of freshwater. In addition to the effect of forced convection caused by a fan, the effects of the water depth, the insulation thickness of the basin base, and the wind velocity have been investigated. The empirical results have been compared with the results obtained from the mathematical model and good agreement has been obtained. The results show that the use of a low-cost fan with negligible power can be an effective and economical way of enhancing the evaporation rate and hence freshwater production. Based on the mathematical model, the daily productivity of freshwater increases up to ∼ 56 per cent at a Reynolds number of 35 000. Finally, an effective range for the wind velocity as well as insulation thickness is presented in order to optimize the production rate of freshwater.

[1]  Varun,et al.  Solar stills: A review , 2010 .

[2]  H. N. Singh,et al.  Present status of solar distillation , 2003 .

[3]  R. Dunkle,et al.  Solar water distillation: the roof type still and the multiple effect diffusor , 1961 .

[4]  Nagamany Nirmalakhandan,et al.  Sustainable desalination using solar energy , 2010 .

[5]  E. Delyannis,et al.  Desalination by using alternative energy: Review and state-of-the-art , 2007 .

[6]  H. M. Ali.  Experimental study on air motion effect inside the solar still on still performance , 1991 .

[7]  G. N. Tiwari,et al.  Monthly performance of passive and active solar stills for different Indian climatic conditions , 2004 .

[8]  Gholamreza Karimi,et al.  Mathematical modelling of solar stills in Iran , 1995 .

[9]  A. A. El-Sebaii.  Effect of wind speed on some designs of solar stills , 2000 .

[10]  E. Delyannis,et al.  Historic background of desalination and renewable energies , 2003 .

[11]  B. Abu-Hijleh.  Effect of water emissivity on solar still efficiency , 2003 .

[12]  V. E. Denny,et al.  Laminar Film Condensation From a Steam-Air Mixture Undergoing Forced Flow Down a Vertical Surface , 1971 .

[13]  H. M. Ali.  Effect of forced convection inside the solar still on heat and mass transfer coefficients , 1993 .

[14]  Zhang Xiaoyan,et al.  A group of improved heat and mass transfer correlations in solar stills , 2002 .

[15]  W. Beckman,et al.  Solar Engineering of Thermal Processes , 1985 .

[16]  Romdhane Ben Slama,et al.  Hybrid solar still by heat pump compression , 2010 .

[17]  Pr. Kaabi Abdenacer,et al.  Impact of temperature difference (water-solar collector) on solar-still global efficiency , 2007 .

[18]  A. E. Kabeel,et al.  Cost analysis of different solar still configurations , 2010 .

[19]  K. Srithar,et al.  Performance analysis in stepped solar still for effluent desalination , 2009 .

[20]  B. A. Jubran,et al.  Effect of climatic, design and operational parameters on the yield of a simple solar still , 2002 .

[21]  R. Ishiguro,et al.  Heat and Mass Transfer With Liquid Evaporation Into a Turbulent Air Stream , 1986 .

[22]  H. M. Ali.  Mathematical model of the solar still performance using forced convection with condensation process outside the still , 1991 .

[23]  T. V. Arjunan,et al.  Active solar distillation--A detailed review , 2010 .