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Table 2 Researches on designs of passive solar still

From: A comprehensive decade review and analysis on designs and performance parameters of passive solar still

S. no. Researchers Still type and geometry Parameters studied Modification/methods/analysis Results/achievements Conclusions/remarks
1. Abderachid and Abdencer (2013) Double slope symmetrical (DSS), and single slope double effect asymmetrical still (SSDAS), basin area—1 m2, condensing cover inclination—10°, 30°, and 45° (Fig. 10) Effect of orientation, tilt angle, and water depth Simulation study to compare the effect of DSS and SSDAS with different orientations and design parameters Asymmetrical double effect solar still gives higher distillate output than symmetrical double slope still South-North orientation of still, 10° tilt angle and 0.02 m water depth gives higher yield. However, these results are concluded only for one day data
2. Omara et al. (2013) Stepped solar still (SS), basin area—1.16 m2, cover inclination—30° (Fig. 11) Effect of internal reflectors SS with internal reflectors Increase of 75 and 57 % in productivity and 56 and 53 % in daily efficiency was observed in stepped solar still with and without internal reflectors, respectively SS with and without internal reflectors shows better output than conventional stills. However, daily efficiency of SS with and without reflectors is not increased significantly (3 %)
3. Rajaseenivasan and Murugavel (2013) Double slope single and double basin still, basin area—0.63 m2, cover inclination—30° Water depth, and solar radiation Theoretical and experimental validation of double slope single and double basin still Maximum production of 4.75 l/m2/day (85 % higher) with double basin still At lower water depth lower basin production is higher than upper basin
Cost and maintenance for double basin still are concluded higher than single basin still
4. Arunkumar et al. (2013b) Tubular solar still with rectangular basin, basin capacity—2 × 0.03 × 0.025 m Condensing cover cooling with water and air, cost analysis Compound parabolic concentrator concentric tubular solar still Distillate output of 1.5 kg/m2 day and 2.5 kg/m2 day with a cost of approximately $0.018 and $0.015 per kg water was observed with air and water cooling, respectively Water flow cooling gives more output than air flow cooling
Cost estimation of solar still in their study not includes maintenance, labor and other service charges
5. Ziabri et al. (2013) Cascade-type inclined solar still, basin area—1.16 m2, condensing cover inclination—20° Weir dimensions Weirs were constructed on each step of absorbing plate of inclined type of solar still 6.7 l/m2/day distillate was collected with modified cascade solar still Weir of appropriate size helps to improve the productivity of solar still. However, saline water flow rate can be optimized for better distillate output for the proposed still
6. Anubraj et al. (2013) Inclined solar still, basin size—1 × 0.75 × 0.157 m condensing cover inclination—25°, 30°, 35° Inclination angle (25°, 30°, 35°), wick materials (black cotton cloth, jute cloth, waste cotton pieces), energy storage and permeable materials (mild steel pieces, clay pot) Modification in design of inclined solar still with rectangular grooves and ridges on absorber plate 30° inclination angle facing south yield maximum of 3.77 l/day
Increase of 12 % productivity was observed using black cotton cloth in basin liner
Energy storage and wicks improve the performance of a solar still at low cost. However, thickness of the wick materials needs to be optimized for future work
7. Ahsan et al. (2014) Triangular solar still (TrSS), length, height, and width of TrSS—1, 0.44, and 0.5 m, respectively Water depth, solar radiation intensity, and ambient temperature TrSS fabricated with low, lightweight, and locally available materials Correlation formulated between water depth (d w) and distillate output (P d) as: P d = 3.84 − 0.47 d w, for 1 ≤ d w ≥ 6 cm Inverse relationship between daily productivity and water depth, and direct relationship with solar radiation. However, the suggested correlation has been formulated by collecting the data for 3 months only
8. Suneesh et al. (2014) V-type solar still, basin area—1.5 m2 (Fig. 12) Condensing cover cooling Cotton gauge top cover cooling (CGTCC) with and without air flow 4.3 l/m2 distillate with CGTCC and 4.6 l/m2 with air flow along with CGTCC CGTCC without air flow is cost-effective modification. However, hot water supply inside the still with CGTCC may be taken as an objective for increased distillate output
9. Sathyamurthy et al. (2014) Triangular pyramid solar still, basin area—1 m2 Energy storage material Paraffin wax in heat reservoir integrated with the still 20 % (4.3 l/day) increase in distillate using phase change material (PCM) Distillate output of solar still is improved using PCM, but it mainly depends on the specific heat capacity, latent heat of fusion, thermal conductivity and proper utilization of storage material
10. Arunkumar et al. (2012) Hemispherical solar still, basin diameter—0.95 m (Fig. 13) Cover cooling Hemispherical top cover, water quality and cost analysis 4.2 and 3.6 l/m2/day of distillate were observed with and without condensing cover cooling Condensing cover cooling improves the performance of solar still, but there are some vapor losses from the flowing water