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 thermo-physical characteristic of novel multi-wall carbon nanotube-Therminol-55-based nanofluids for solar-thermal applications.

This work aims to develop a novel nanofluid using Therminol-55 (T-55) as heat transfer fluid and multi-wall carbon nanotubes (MWCNTs) as dispersants with various volume concentrations of 0.05, 0.1, 0.3, and 0.5% and assess its thermo-physical properties for solar-thermal applications. The pH values of nanofluid MWCNT/T-55 with various particle loading were too far-flung from the pH (I) value, which confirmed the good dispersion stability of nanofluid. The measured density shows tremendous deviation from predicted density with increasing MWCNT loading owing to the non-considering of microstructural parameters in Pak & Cho correlation predication. The highest augmentation in nanofluid thermal conductivity was 16.83% for 0.5 vol. % MWCNT at 60 °C. The maximum improvement in dynamic viscosity of nanofluid with 0.5 vol. % of MWCNT is found to be 44%, and this rise is reduced at higher temperatures. The thermal effectiveness of the nanofluids demonstrates that nanofluid with all volume fractions of MWCNTs was favorable at higher temperatures in the laminar region. Mouromtseff number ratio decreases with a rise in temperature and MWCNT volume concentration. It is concluded that the excellent thermo-physical properties and prolonged thermal stability of the MWCNT will be highly beneficial in improving the overall performance of various kinds of heat transfer fluids (HTFs) for process heating and solar-thermal applications.