Year-round comparative study of three types of solar desalination units

Simulations of three different types of solar stills were performed to compare their productivity using typical meteorological year data of a remote location (Marmul) in Oman. These are the regenerative, conventional, and still with double-glass-cover cooling. Several system parameters were also investigated with respect to their effect on the productivity, namely, water with and without dye in the lower basin, basin heat loss coefficient, mass of water in the basins, and mass flow rate into the double-glass cover. The regenerative still had more than 70% higher productivity in comparison with the conventional still. If the stills are appropriately insulated, the conventional still had higher productivity than the double-glass-cover cooling. Increasing the water in the lower basin moderately reduced the productivity of the three stills. Increasing the water film thickness on top of the lower glass had no effect on the productivity of the still with double-glass-cover cooling, but slightly lowered the productivity of the regenerative still.

Generally, hour-by-hour, year-round simulations are necessary to draw solid conclusions on the performance of thermal devices operating under variable conditions such as weather. Furthermore, the use of typical meteorological data is essential for comparative studies of the performance of thermal devices. The results indicate that the regenerative still gives more than 70% higher productivity in comparison with a conventional still. If the stills are appropriately insulated, the conventional still [1] G.N. Tiwari and V.S. Rao, Transient performance of single basin solar still with water flowing over glass cover, Desalination, 49 (1984) 231–239. [2] G.N. Tiwari, Madhuri and H.P. Garg, Effect of water flow over the glass cover of a single basin solar still with an intermittent flow of waste hot water in the basin, Energy Convers. Mgmt., 25 (1985) 315–322. [3] S.A. Lawrence, S.P. Gupta and G.N. Tiwari, Effect of heat capacity on the performance of solar still with water flow over the glass cover, Energy Convers. Mgmt., 30 (1990) 277–285. [4] B.A/K. Abu-Hijleh, Enhanced solar still performance using water film cooling of the glass cover, Desalination, 107 (1996) 235–244. [5] B.A/K. Abu-Hijleh and H.A. Mousa, Water film cooling over the glass cover of a solar still including evaporations effects, Energy, 22 (1996) 43–48. [6] G.N. Tiwari and R. Kamal, eds., Solar Energy and Energy Conservation, Wiley Eastern, New Delhi, 1992, pp. 32–149. [7] M.K. Abu-Arabi, Y.H. Zurigat, H. Al-Hinai and S. Hiddabi, Modeling and performance analysis of a solar desalination unit with double glass cover cooling, Desalination, 143 (2002) 173–182. [8] A.K. Singh and G.N. Tiwari, Thermal evaluation of regenerative active solar distillation under thermosyphon mode, Energy Convers. Mgmt., 34 (1993) 697–706. [9] J. Prakash and A.K. Kavanthekar, Performance prediction of a regenerative solar still, Int. J. Solar Wind Tech., 3 (1984) 119–131. [10] H. Al-Hinai, M.S. Al-Nassri and B.A. Jubran, Parametric investigation of a double-effect solar still in comparison with a single-effect solar still, Desalination, 150 (2002) 75–83.