Two new designs of wind towers were tested side by side with a conventional wind tower in the city of Yazd, Iran. All the towers were of identical dimensions. The two new designs were one with wetted column, consisting of wetted curtains hung in the tower column, and the other one with wetted surfaces, consisting of wetted evaporative cooling pads mounted at its entrance. The air temperature leaving the wind towers with evaporative cooling provisions were much lower than the air temperature leaving the conventional design, and its relative humidity much higher. The air-flow rate was reduced slightly in these new towers. It was found that the wind tower with wetted column performs better with high wind speeds whereas the tower with wetted surfaces performs better with low wind speeds. It is recommended that these new designs of wind towers should be manufactured in different sizes and incorporated in the designs of new buildings. They can replace the evaporative coolers currently employed in Iran, and other hot arid regions, with considerable saving in electrical energy consumption. r

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In this paper, the behavior of a salt-gradient solar pond with the square cross-section has been studied experimentally and numerically. A small-scale solar pond were designed and built to provide quantitative data. A two-dimensional, transient heat and mass transfer model has been solved numerically by using finite-control-volume method. In this study, all the thermo-physical properties are variable as the function of temperature and salt concentration. Numerical results as obtained for the experimental pond have been satisfactorily compared and validated against measured data. Furthermore, the wall shading effect has been elaborated to improve the agreement between two sets of results. The temperature of the storage zone is predicted well by the model. It also can be observed that the initial concentration profile is preserved with time. The stability of the pond in time has been investigated in order to distinguish the critical zones. Finally, the application of an energy analysis gives an efficiency of about 12% for the pond.