Water depth effect on energy, exergy losses, and exergy efficiency of solar still with wick materials: an experimental research.

This study analyzes the energy and exergy destruction of a solar still with black painted wick materials (SS with BPWM) at different salt water depths (Wd) of 1, 2, and 3 cm. The coefficients of heat transfer for evaporative, convective, and radiant heat transfer have been calculated for a basin, water, and glass. The thermal efficiency and exergy losses caused by basin material, basin water, and glass material were also determined. An SS with BPWM at Wd of 1, 2, and 3 cm has produced a maximum yield of 0.4, 0.55, and 0.38 kg per hour, respectively. An SS with BPWM at Wd of 1, 2, and 3 cm has produced a daily yield of 1.95, 2.34, and 1.81 kg, respectively. From the SS with BPWM at Wd of 1, 2, and 3 cm, respectively, daily yields of 1.95, 2.34, and 1.81 kg were obtained. The highest exergy loss of the glass material, basin material, and basin water for the SS with BPWM at 1 cm Wd was 728.7, 133.4, and 123.8 W/m2, respectively. The SS with BPWM's thermal and exergy efficiency are 41.1 and 3.1% at 1 cm Wd, 43.3 and 3.9% at 2 cm Wd, and 38.2 and 2.9% at 3 cm Wd, respectively. The results show that compared to the exergy loss of basin water in SS with BPWM at 1 and 3 cm Wd, the basin water exergy loss of SS with BPWM at 2 cm Wd is minimal.

Energy and exergy analysis of conventional acrylic solar still with and without copper fins.

A detailed exergy analysis of a conventional and copper finned acrylic solar still has been presented in this manuscript. The evaporative, convective, and radiative heat transfer coefficient of water-glass has been calculated. Also energy efficiency, exergy destruction of basin, water, and glass has been determined. Conventional acrylic solar still with fins produced maximum hourly output of 1.24 kg and it produced daily output of 5.08 kg. The conventional acrylic solar still without fins produced maximum hourly output of 0.94 kg and it produced daily output of 3.75 kg. The maximum exergy destruction of the basin, water, and glass for the conventional acrylic solar still with fins are 655.206, 83.35, and 90.48 W/m2, respectively, and conventional acrylic solar still without fins are 616.28, 122.34, and 48.64 W/m2, respectively. The energy and exergy effectiveness of the conventional acrylic solar still with fins are 32 and 2.81%, respectively, and without fins are 24.93 and 1.69%, respectively. The study reveals that exergy destruction of water in the case of still with fins is minimum as related to the exergy destruction of water in the case of still without fins.

Inferences on the effects of geometries and heat transfer fluids in multi-cavity solar receivers by using CFD.

This paper discusses about the design and analysis of a novel multi-cavity tubular receiver developed for small- and medium-scale concentrated solar power applications from the existing basic baffle-plated volumetric receiver model which is used in large-scale applications. The design and analysis work has been completed to enhance the thermal performance of cavity receivers for the average solar power input of 12 kW with a dish concentrator of 15 m2 aperture area. This was carried out by replacing the baffle plates from the conventional basic volumetric receiver with multi-cavity tubes, keeping the heat transfer area as constant. The tubular arrangement improves the flow and heat transfer characteristics through minimized pressure drop. The receiver models with aluminum, copper, and silicon carbide materials have been analyzed using commercially available CFD software ANSYS-FLUENT for different flow rates of air and water. The computational analysis reveals that the thermal performance of a modified multi-cavity tubular receiver model made up of SiC material is better than receiver model with aluminum and copper materials. The maximum energy efficiency of 21.11% and 75.81% are achieved by the heat transfer fluids air and water, respectively. The maximum efficiency is achieved at the flow rate of 1.35 l/min and 0.9 l/min for the heat transfer fluids air and water, respectively. The study concludes that the multi-cavity tubular configurations may be well suited for small-scale CSP applications than the volumetric receivers with foams, rods, honeycomb, and baffle-plated structures.