Tenth International Water Technology Conference, IWTC10 2006, Alexandria, Egypt 249 PV AND THERMALLY DRIVEN SMALL-SCALE, STAND-ALONE SOLAR DESALINATION SYSTEM WITH VERY LOW MAINTENANCE NEEDS Hassan E. S. Fath*, Samy M. Elsherbiny and Alaa A. Hassan Mech. Eng. Dept., Alexandria Univ., Alexandria, Egypt E-mail h_elbanna_f@yahoo.com Matthias Rommel, Marcel Wieghaus and Joachim Koschikowski Fraunhofer Institute for Solar Energy Systems ISE, Germany Mostafa Vatansever Fentec, Turkey ABSTRACT This paper presents the thermal performance of a membrane distillation (MD) solar desalination unit located in the Mechanical Engineering Department site, Alexandria University, Alexandria, Egypt. The unit is designed and installed as a part of a partially funded European Commission (EC) project named; “PV and thermally driven small-scale, stand-alone desalination system with very low maintenance needs (SMADES)”. The basic innovative MD principle and module is highlighted. The Alexandria MD unit is described and the unit performance is presented for the 6-months of its operation period. The unit performance covers; the transient changes in the unit productivity, unit feed water, brine and product water temperatures and conductivities, unit salt rejection, solar collector and MD process efficiencies. The unit performance, in clear and cloudy days, for typical summer and winter months, is presented. For a sunny day, of 7.25 kWh/day say, the results indicate that the unit produces about 11.2 liter/day for every square meter of collector area. The relatively high productivity, above that of the conventional solar still, is due to the partial recovery of the condensation energy. The overall unit productivity has been correlated against the solar irradiation as: 1.67 - .day) (kWh/m radiation Daily 1.666 .day) (lit/m production Daily 2 2 × = Keywords: Desalination, Membrane Distillation, Solar Energy INTRODUCTION The international rapid developments, the industrial growth, and population explosion all over the world have resulted in a large escalation of demand for fresh water. On the other hand, the surface water (rivers and lakes) pollution caused by industrial and agricultural wastes and the large amount of sewage, limit the suitability of many fresh