Experimental performance evaluation of a stand-alone point-focus parabolic solar still

A stand-alone point-focus parabolic solar still (PPSS) was designed and fabricated for desalination of seawater or brackish water and purification of non-potable water. The system consists of a parabolic dish concentrator; a two axis sun tracker based on programmable logic controllers (PLCs) and two plate heat exchangers (PHEs) to preheat the salt water before entering the absorber located at the focal point as well as condense the generating steam. Distillate productivity of the PPSS was measured along with evaluation of the effects of environmental and operational parameters that includes: beam solar insolation, wind speed, air temperature, absorber wall temperature and raw water salinity under the climatic conditions of Tehran during October. The maximum productivity of 5.12 kg within 7 h in a day was measured with the maximum average solar insolation of 626.8 W/m2 and the absorber wall temperature of 150.7 °C. However, no significant effect of air temperature, wind speed, and water salinity on the productivity was observed. The maximum daily efficiency of 36.7% was calculated with a maximum hourly output of 1.5 kg/h. The quality of lab-prepared salt water samples was analyzed before and after desalination and the results comply with the WHO guidelines for drinking water quality.

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