Comparative study on stepped solar distillers internally loaded with different masses of phase change material
Rahul Grewal, Mahesh Kumar
Abstract
This experimental work discusses the thermo-enviro-economic analyses for effect of mass of paraffin wax as phase change material (PCM) on solar distillation in inclined stepped solar still (SSS). Three identically designed SSS units, namely, S1, S2, and S3 respectively, laden with 0.45, 0.90, and 1.35 kg of PCM filled in copper tubes are fabricated and tested at 25 mL/min flow rate. The findings of the experimental study manifested that the performance of SSS unit is significantly improved as the mass of the PCM is increased. The amount of distillate produced by units S1, S2, and S3 are respectively, 1.99, 2.12, and 2.18 kg. The distillate obtained from S3 unit is 8.4% and 2.6% more than S1 and S2 units, respectively. The average values of energy and exergy efficiencies of this unit are evaluated as 31.53% and 2.15%, respectively. This unit is capable to mitigate 8.28 t of CO2 per year which is 7.6% and 2.1% higher than that of units S1 and S2, respectively. Carbon credit earned by units S1, S2 and S3 are respectively, $114.78, $121.58, and $124.23. The carbon credit earned from S3 unit is the highest among tested units which inferred that unit S3 is environmentally friendlier. The total productive cost of environmentally and thermally supreme unit S3 is evaluated as $0.30 which is 6.67% and 3.34% higher than that of S1 and S2 units, respectively. The study shows that the use of PCM in solar distillation has the potential to improve its productivity which helps to eradicate the scarcity of potable water. Highlights The effect of mass of paraffin wax loading on the performance of stepped solar still is presented. Thermo-enviro-economic performance of system is observed to improve with increase in mass of paraffin wax loading. The system loaded with 1.35 kg paraffin wax is found best in environmental conservation and can mitigate 8.28 t CO2 per year. The total productive cost per day of the unit having maximum mass of paraffin wax is $0.30.