Energy, exergy, environmental benefits and economic aspects of novel hybrid solar still for sustainable water distillation

Abstract

In this work, a novel hybrid solar still which occupies less ground area has been proposed and investigated under the climatic conditions of Chennai, India. Hybrid solar still is formed by integrating basin solar still and vertical diffusion still. The proposed unit has been thermodynamically modeled and the effect of area ratio of basin to vertical absorber, diffusion gap, basin water depth, shade and feed water flow rate on unit’s performance has been investigated. Optimum vertical diffusion still absorber area to basin area ratio, diffusion gap, basin water depth and feed water flow rate are found to be 2.0, 0.02 m, 0.02 m and two & half times the condensate production rate in vertical diffusion solar still, respectively. Shading of vertical absorber is found to decline the overall condensate production rate in a rapid manner. Exergy efficiency, exergy destruction and improvement potential of each component of hybrid solar still for all months has also been reported. The hybrid solar still is found to have high performance in winter seasons rather than summer seasons. Maximum condensate productivity rate, thermal and exergy efficiency of the optimized hybrid solar still is about 13.79 kg/d, 56.17 % and 6.93 %, respectively. Condensate production cost per litre ranges between 1.10 INR/L to 3.83 INR/L depending on wick replacement frequency, interest rate and life span of the unit. Energy payback time and finance payback time of the unit is within 1.2 Year and within 4.0 Year, respectively. Net CO2 emission, SO2 emission and NO emission mitigated by the unit ranges between 23.4–63.1 tons, 168.0–453.8 kg and 68.6–185.6 kg, respectively. Reasonable condensate production rate with acceptable price and environmental benefits has made this proposed still more promising for practical applications.