Experimental performance investigation of tilted solar still with basin and wick for distillate quality and enviro-economic aspects
Tilted wick type and stepped solar stills are well known for their increased distillate yield compared to basin type stills. In this study experiments were conducted on tilted solar still with basin and tilted solar still with wick to assess their performance, distillate quality, environmental benefits and economic feasibility. Distillate quality of both the tested units was superior. Annual average distillate yield of tilted solar still with basin was nearly 19.76% higher than that of the unit with wick. Maximum distillate yield of 4.99 L/d and 4.54 L/d was noticed for tilted solar still with basin and wick, respectively during April. Yearly average thermal and exergy efficiency was around 41.06% and 3.06% for the unit with basin and 33.83% and 2.88% for the unit with wick. Energy payback time of the unit with basin was around 2.80 yrs and it can prevent 17.65 tons of CO2emission during 20 yrs of life time. Distillate production cost was around 0.026 USD/L (Rs. 1.74/L) and 0.046 USD/L (Rs. 3.08/L) for an interest rate of 5% and 12%, respectively. Tilted solar still with basin has superior performance compared to that of unit with wick and can produce 21.76 L of distillate/USD invested on it.
Energy and environmental analysis of multi-effect active vertical solar desalination unit for Indian conditions
Environmental benefits and economic feasibility of evacuated multi-effect vertical solar desalination unit have been estimated for various coastal regions of India. Maximum annual average daily distillate yield and performance ratio of 29.43 kg/m2-d and 4.29 were recorded for Panaji. The unit was found to be capable of mitigating CO2, SO2 and NO emissions in the range of 74.74–137.65 tons, 730.53–989.70 kg and 225.75–404.27 kg, respectively, for considered east coast locations of India. Net CO2, SO2 and NO emission mitigation in the range of 115.01–149.36 tons, 872.07–1073.94 kg and 337.75–438.65 kg, respectively, was noticed for coastal regions in western part of India. Energy payback period of the unit was well below 1.5 yr for all the considered locations. Lowest distillate production cost of 0.79 INR/L and 0.73 INR/L was noticed for east and west coast region of India.
Performance investigation and enviro-economic analysis of active vertical solar distillation units
In this work, performance enhancement of vertical still by active mode operation was carried out using mathematical modeling. The reported model is validated with the mass transfer model that is usually employed for prediction of mass transfer in vertical stills. The two configurations considered for active mode operation are CVDS (cascaded vertical-double slope) still and CVSS (cascaded vertical-single slope) still. The optimum absorber area and gap between condensing and evaporating surface is 4m2 and 0.20m, respectively. Effect of shade on system performance has also been reported. CVDS and CVSS unit produces nearly 25.63% and 13.33% higher distillate than the passive vertical still of similar dimensions. The yield is found to decrease by 10% for every 5% increase in salinity of feed. Maximum yield of 24.06kg/d is recorded for CVDS unit during the month of April. CVDS unit has maximum energy payback period of 2.25 years and can mitigate at least 69.85 tons of CO2 emission during its life time of 20 years and can provide distilled water at 34.3 USD/kL or less. High yield, low water production cost and less ground area occupancy make the unit more feasible and competitive for rural and urban applications.
Active multi-effect vertical solar still: Mathematical modeling, performance investigation and enviro-economic analyses
In this paper, year round performance and enviro-economic analyses of active multi-effect vertical solar still were carried out using the developed comprehensive mathematical model. The optimum number of effects, mass flow rate of feed water and gap between the effects were found to be five, 7.20 kg/h and 0.05 m, respectively. Maximum annual average distillate yield of 6.78 and 21.29 kg/m2-d was noticed for the optimized unit under normal mode and low pressure mode operation. Maximum annual average Performance ratio (PR) and Solar energy Coefficient of Performance (SCP) of 5.59 and 3.03 was noticed under evacuated mode operation. Energy payback time and distilled water production cost of the evacuated unit treating 5 wt% saline water was around 1.37 yrs and Rs.2272.00/m3 (33.00 USD/m3), respectively and it can effectively mitigate at least 81.81 tons of CO2 emission during its life time of 20 yrs. Distilled water production cost of the evacuated unit was found to reduce from Rs.2270.00/m3 (33.00 USD/m3) to Rs.1310.00/m3 (19.00 USD/m3) by decreasing the interest rate from 12% to 5%. Salinity of feed water and interest rate at which the unit was financed played a major role in distilled water production cost.