Experimental investigation of using an evaporation inhibitor layer in a solar still

This paper presents an experimental study of the effect of an evaporation inhibitor layer (EIL) on solar still performance in terms of productivity and production efficiency. The EIL effect significantly increases the temperature of water by restricting its reflection of sunlight. The resultant extra energy is transferred to brine to enhance the water evaporation rate. Olive oil was used as an inhibitor layer, and several experiments were carried out in a solar simulator with an evaporating dish that contained water. First, the temperature difference between two systems (one with and one without an EIL) was measured to determine the effect of the EIL. A temperature difference of 7.4 degrees C was recorded after two hours. Then, an EIL was applied to a new solar still, in which the evaporation rate was enhanced via still warming due to the effects of the EIL and direct solar radiation. This finding was validated by comparing the temperature and evaporation rates of solar stills with and without an EIL. The results confirm that under constant conditions and with equal surface areas, the water production in a solar still with an EIL is at least 28% higher than when an EIL is not used. Moreover, the results show that the cost of producing water using this technique is lower than when using other methods and has a considerably low payback time.