Utilization of ensemble random vector functional link network for freshwater prediction of active solar stills with nanoparticles

Experimental investigation on dish solar distiller with modified absorber and phase change material under various operating conditions

The shortage of potable water is a global problem. One of the techniques used to participate solving this problem is the solar distiller. The main demerit of solar distiller is its low output yield. So, this work aims at improving the freshwater productivity of a dish solar distiller by enlarging its absorber surface area and increasing its evaporation rate. As a result, the effect of using three different shapes of absorber liner was investigated: convex dish absorber, stepped absorber, and corrugated surface over the stepped absorber. In addition, the absorber of dish distiller was covered by a cotton wick to enlarge the wetted surface area. Also, different water depths (1.0, 2.0, 3.0, 4.0, and 5.0 cm) in dish distiller with stepped absorber were investigated. Moreover, the distance below basin liner was occupied by energy storing medium (paraffin wax + titanium oxide nanoparticles). The performances of dish distiller, dish distiller with stepped absorber, and dish distiller with corrugated absorber were evaluated and compared to that of a conventional solar distiller. Experimental results revealed that the performance of dish distiller with corrugated absorber, wick, and energy storing material was higher than that of dish distiller with stepped absorber, which was better than that of dish distiller, which was higher than that of conventional distiller. As well, the highest improvement in productivity of dish distiller with stepped absorber was 125% compared to conventional distiller and took place at 2-cm water depth. In addition, the productivity of dish distiller with corrugated absorber and wick was improved by 160% compared to that of conventional distiller. Additionally, the highest performance was obtained for dish distiller with corrugated absorber, wick, and energy storing material, where the productivity was augmented by about 183%, and the thermal efficiency reached 69.5%.

Improving the potable water generation through tubular solar still using eggshell powder (bio-based energy source) as a natural energy storage material - an experimental approach

The demand for fresh water is rapidly growing as a consequence of the increasing population and urbanization. Tubular solar still offers larger evaporative and condensing surface area as compared to single slope solar still. The aim of this study is to improve the performance of tubular solar still by employing eggshell powder (collected from Babcobb Broilers chicken) as the sensible energy storage material in form of bed, placed inside the basin of still to improve the water production. Results showed that the influence of eggshell powder as energy storage material in the basin improved the average water temperature by 3%, 6.2%, and 3.2% for the water thickness of 10, 15, and 20 mm, respectively. The usage of eggshells as a sensible energy storage in the basin augmented the peak hourly water yield by 67.64% with minimum water thickness. The total observed distillate output from the solar still is 1.45 kg without eggshell powder and 2.67 kg for with eggshell powder in the absorber at the lowest water thickness of 10 mm. TSS with eggshell powder as energy storage has a daily energy efficiency of 48.17%, 42.38%, and 36.38%, respectively, for water thicknesses of 10, 15, and 20 mm in the basin. Water thickness of 10, 15, and 20 mm has performance improvement ratios of 1.83, 1.81, and 1.78, respectively. Using cost analysis, it was found that the cost of drinkable water generated using eggshell as an energy storage material is 0.011$/kg, but the cost of water by traditional still without any storage material was 0.021$/kg.

Investigating the performance of dish solar distiller with phase change material mixed with Al2O3 nanoparticles under different water depths

The problem of potable water shortage all over the world made the scientists seek for solutions to overcome this problem. Solar distiller is one of the introduced solutions, but it demerited by the low freshwater output. In this proposed paper, a design modification includes the use of a convex dish absorber instead of the flat absorber liner. The modified solar distiller is nominated by dish solar distiller. The base of dish solar distiller was circular. In addition, a cotton wick was used as a wetting material for facilitating the evaporation process inside the distiller. Besides, the effect of different water heights in the clearance around the dish dome was investigated for 1, 3, 5, 7, 9, and 12 cm. Finally, the space under the dish absorber is filled with a phase change material of paraffin wax mixed with aluminum oxide nanoparticles. Experimental results revealed that the best dish height that provided the highest freshwater productivity was 9 cm, where the average daily yields of dish solar distiller (at 9 cm) and conventional distillers were reported as 4500 and 3000 mL/m².day, respectively. Then, the productivity of dish solar distiller was improved by around 50% over that of the conventional distiller. In addition, when using the phase change material, the average daily distillate of dish solar distiller was improved by approximately 95% compared to that of the conventional solar still, where the distillate of conventional still and dish solar distiller with phase change material at 9 cm water depth was 3580 and 6980 mL/m².day, respectively. Besides, the maximum thermal efficiency of dish solar distiller was obtained when using phase change material at 9 cm water depth, where it was 62.4% compared to 30% for the conventional distiller.

Applications of Heat Exchanger in Solar Desalination: Current Issues and Future Challenges

Solar desalination is a process to convert saline water into potable water by the application of solar energy. The enhancement of the distillate output of the solar desalination is low, so it is not considered as a method to produce potable water. A heat exchanger is an important device used for heat transfer applications. The present review article illustrates the application of a heat exchanger with a solar desalination system to enhance the distillate output. In the current review, it is found that the heat exchanger is an important device to improve the distillate productivity of the solar desalination system. Finally, the future work and future challenges of using a heat exchanger with a solar desalination system are presented.