On effect of wind speed on passive solar still performance based on inner/outer surface temperatures of the glass cover

摘要

The thermal performance of a passive single basin solar still was investigated by computer simulation using the climatic conditions of Jeddah (lat. 21° 42' N, long. 39° 11' E), Saudi Arabia under the two conditions: (a) the temperatures of the inner T_(gi) and outer T_(go) surfaces of the still cover are equal and (b) the temperatures of the inner T_(gi) and outer T_(go) surfaces of the still cover are not equal. Effect of wind speed Von the daily productivity P_d of the still for these conditions was studied. It was indicated that for the condition T_(gi) = T_(go), there is a critical mass (depth) of basin water beyond which P_d increases as V increases until a typical velocity V_(t.) For basin water masses less than the critical mass, P_d was found to decrease with increasing V until V_(t.) After V_(t.) the change in P_d becomes insignificant. When T_(gi) ≠ T_(go),P_d was found to be less dependent on wind speed V for all investigated values of mass of basin water m_w in the range 0 < m_w < 100 kg. The rate of heat transfer by forced convection due to wind should be estimated on the basis of the temperature of the upper surface of the still cover.