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This study focuses on the enhancement of potable water productivity of an active double slope modified solar still (SS) considering the combined effect of solid rectangular fin, paraffin wax as a thermal energy storage medium, black cotton cloth as wick material, and an external condenser. The performance of three double slope SSs (modified, finned, and traditional) is evaluated considering five different cases. A comparative assessment of the performances of three double slope SSs is performed and it is perceived that the supreme productivities are 3.07, 2.70, and 2.46 L/m2 for modified, finned, and traditional SSs, respectively. The maximum efficiency of the modified SS with and without external condenser are found as 39.74% and 30%, respectively. An external condenser insertion in the modified SS boosts the productivity by approximately 10%. The average daily efficiency of the modified SS is 14.23% and 22.33% higher than the finned and traditional SS, respectively. The economic analysis is also conducted, and the cost per liter (CPL) values for traditional SS, the finned one, and the modified one are found as 0.0135, 0.0133, and 0.0117 $/L/m2, respectively. The novel modification of SS could be a propitious alternative to meet up the potable water demand in remote regions with low cost.

The study presents an analysis and suggests about how renewable sources of energy can be an alternative option to produce electricity in an off-grid area. A case study is done by surveying 235 households in an off-grid area. Techno-economic analysis of the hybrid energy system is employed by using Hybrid Optimization of Multiple Energy Resources (HOMER) software. Four solar-PV modules (each of 1kW), two biogas generators (each of 3kW), three diesel generators (each of 5kW), five batteries (each of 160 Ah) and 5kW converter is found to be the best configuration in terms of Cost of Energy (COE), environmental conditions and Renewable Fraction (RF). The Cost of Energy (COE), Net Present Cost (NPC), capital cost of this configuration is found BDT15.382, BDT10007224, and BDT2582433 respectively. The renewable fraction of this system is found 75% which indicates a lower emission compared with thegrid based system and stand-alone diesel system. Although the COE is higher than grid electricity, this system offers a cheaper option than using kerosene oil and solar home systems (SHSs).

article i nfo In the present study, the heat transfer performance and friction factor characteristics in a circular tube fitted with twisted wire brush inserts were investigated experimentally. The twisted wire brush inserts were fab- ricated with four different twisted wire densities of 100, 150, 200, and 250 wires per centimeter by winding a 1 mm diameter of the copper wire over a 5 mm diameter of two twisted iron core-rods. Heat transfer and friction factor data in tubes were examined for Reynolds number ranging from 7,200 to 50,200. The results indicated that the presence of twisted wire brush inserts led to a large effect on the enhancement of heat transfer with corresponding increase in friction factor over the plain tube. The Nusselt number and friction factor of using the twisted wire brush inserts were found to be increased up to 2.15 and 2.0 times, respective- ly, than those over the plain tube values. Furthermore, the heat transfer performance was evaluated to assess the real benefits of using those type of inserts and the performance was achieved 1.85 times higher compared to the plain tube based on the constant blower power. Finally, correlations were developed based on the data generated from this work to predict the heat transfer, friction factor, and thermal performance factor for tur- bulent flow through a circular tube fitted with the twisted wire brush inserts in terms of wire density (y), Reynolds number (Re), and Prandtl number (Pr).