Economic and exergy analysis of passive solar still incorporated with an additional condensing surface material beneath the top glazing to enhance the productivity.

The main bottleneck haunting the wide dissemination of solar still is its poor yield per unit area. This study aims to overcome the above bottleneck by augmenting the yield of SS by increasing the surface area available for condensation by incorporating an acrylic chamber filled with water beneath the top glass surface. The solar still incorporated with acrylic basin (ACSS) was operated in two different methodologies and its performance was ascertained and compared with the conventional passive solar still (CPSS). The surface area available for condensation in CPSS and ACSS operating in two different modes were 0.52 m2 and 0.87 m2, respectively. The efficiency of the CPSS and ACSS operated in mode I was 24.28% and 28.94% respectively. On the other hand, the efficiency of the CPSS and ACSS operated in mode II was 26.61% and 31.29% respectively. The rate of evaporation of water from the basin of ACSS operated in mode II is enhanced by 42.74% when compared to the CPSS. The increment in evaporation rate can be attributed not only due to the increment in surface area available for condensation but also due to the supply of hot water present in the acrylic chamber to the basin of the ACSS operated in mode II depending on its yield for every half an hour. Meanwhile, replenishment of water in the acrylic chamber every 30 min by water at 30 °C, abets in reducing the lower surface temperature of acrylic chamber which aid in increasing the temperature difference between water in the basin and lower surface of acrylic chamber. Thus, the productivity of ACSS operated in mode II is higher than that of CPSS by 17.59%.

Exploring the photo-thermal conversion behavior and extinction coefficient of activated carbon nanofluids for direct absorption solar collector applications.

This work aims to explore the optical and thermal conversion characteristics of activated carbon-solar glycol nanofluids with various volume fractions namely 0.2, 0.4, and 0.6%, respectively. Kigelia africana leaves were synthesized into porous activated carbon nanomaterials by using the high-temperature sintering process and the pyrolysis process in a muffle furnace. The experimental investigation was carried out with different nanofluid concentrations by using the solar simulator. Nanofluids were heated with the assistance of a solar simulator test system and the convection/conduction heat loss was decreased by using the glass as an insulating material around the test section. Prepared nanofluid with 0.6 vol% activated carbon augmented the thermal conductivity by 14.36% at 60°C. The maximum temperature difference of 10°C was attained at 0.6% volume concentrations of nanofluid as compared with base fluid (solar glycol). In addition, maximum receiver efficiency of 94.51% was attained at 0.6% volume fractions of activated carbon-based nanofluid compared with solar glycol thru a light radiation time of 600 s. Moreover, activated carbon-based nanofluid exhibited significantly higher absorption efficiency as the majority of the radiation was absorbed by the nanofluid. It is concluded that activated carbon-based nanofluids could be a suitable low-cost highly stable material for developing working fluid for direct absorbance solar collector-based applications.