Experimental investigation and theoretical modelling of heat transfer in circular solar ponds by lumped capacitance model

The present study develops a lumped capacitance model for modelling the heat transfer in a salinity gradient solar pond. This model is used to analyze the transient energy behaviour in each zone of the pond incorporating many processes that affect the performance of a solar pond. The effect of various parameters such as different solar attenuation models, thickness of each zone, heat loss from the pond's surface, and the wall-shading effect on the temperature of the storage zone would be investigated. The validity of the model is tested against experimental data for a small circular pond constructed in Urmia University, and a good agreement between theoretical and experimental data for the temperature in the storage zone has been obtained. The results indicated that the heat loss from the pond's surface occurs mostly by evaporation rather than radiation and convection. In addition, it is observed that the upper convective zone thickness should be as thin as possible and the lower convective zone thickness may be designed based on the application needs. It is concluded that wall-shading effect has a significant effect on the storage temperature of a small pond, however, the effect is found to be small in the large pond. (C) 2017 Elsevier Ltd. All rights reserved.