Correlation formulation for optimum tilt angle for maximizing the solar radiation on solar collector in the Western Himalayan region

Solar tracking devices are efficacious in maximizing solar irradiation collection. However, higher price makes these systems less frequently used. As an alternative, optimum tilt angle estimation has the advantage that it does not involve tracking cost expenditure. In this study, optimum tilt angles for different months have been computed for Hamirpur, Himachal Pradesh, India (L 31° 42′ N). Several mathematical models and statistical tools have been employed to forecast the monthly optimum tilt angles for the selected site. Different scenarios have been presented by considering five, four, three, and two annual adjustment models to increase the practical usage of the estimated optimum tilt angles. Additionally, cost-benefit analysis has also be performed on the PV panels. Based on the results, it has been concluded that model M − 11, with three annual adjustments, stipulates maximum benefits over the other models. This study can serve as fundamental guidance for setting up solar energy plants in this specified region with the highest efficiency

Assessment of braking performance of lapinus–wollastonite fibre reinforced friction composite materials

Brake friction materials comprising of varying proportions of lapinus and wollastonite fibres are designed, fabricated and characterized for their chemical, physical, mechanical and tribological properties. Tribological performance evaluation in terms of performance coefficient of friction, friction–fade, friction–recovery, disc temperature rise (DTR) and wear is carried out on a Krauss machine following regulations laid down by Economic Commission of Europe (ECE R-90). The increase in wollastonite fibre led to an increase in density and hardness whereas void content, heat swelling, water absorption and compressibility increased with the increased in lapinus fibre. The performance coefficient of friction, friction–fade behaviour and friction–stability have been observed to be highly dependent on the fibre combination ratio i.e. coefficient of friction, fade and friction–stability follow a consistent decrease with a decrease in the lapinus fibre content, whereas the frictional fluctuations in terms of μmax − μmin have been observed to increase with a decrease in lapinus fibre content. However, with an increase in wollastonite fibre content in formulation mix, a higher wear resistance and recovery response is registered. The worn surface morphology has revealed topographical variations and their underlying role in controlling the friction and wear performance of such brake friction composites

Experimental investigation on overall thermal performance of fluid-flow in a rectangular channel with discrete V-pattern baffle

This work presents the results of an experimental study of thermohydraulic performance of rectangular channel having discrete V-pattern baffle attached on the broad wall. Measurements have been carried out for the aspect channel ratio of 10, Reynolds number from 3000 to 21000, relative baffle height value of 0.50, relative baffle pitch value of 1.5, relative gap width value of 1.0, flow attack angle value of 60°, and relative discrete distance values of 0.26 to 0.83. The heat transfer and friction factor data obtained were compared with the data obtained from a smooth wall channel under similar operating conditions. In comparison to the smooth wall channel the discrete V-pattern baffle channel enhanced the Nusselt number and friction factor by 3.89 and 6.08 times, respectively. The overall thermal performance parameter is found superior for the relative discrete distance of 0.67. Discrete V-pattern baffle roughness shape has also been shown to be overall thermal performance higher in comparison to other continuous (without discrete) V-pattern baffle shape rectangular channel

Exergy based modeling and optimization of solar thermal collector provided with impinging air jets

The irreversible absorption of solar energy accompanied by emission for conversion into thermal energy takes place at the cost of exergy losses from the collector and the effectiveness of this conversion is evaluated in terms of exergy efficiency based upon second law of thermodynamics. Presented in this paper is the exergetic efficiency of impinging jet solar thermal collector and its comparison with that of conventional solar collector. The effect of flow Reynolds number, jet diameter, streamwise and spanwise pitch between the jets on exergetic efficiency of impinging jet solar air collector during conversion of solar energy into thermal energy has been studied based upon the correlations developed for heat transfer coefficient and friction factor in the range of investigated flow and geometric parameters. The results reveal that the impinging air jets extract the absorbed exergy from the absorber to the air flowing beneath with higher efficiency than that of the conventional solar air collector. Also, the design plots have been prepared for jet plate parameters with temperature rise parameter in order to obtain an optimum parameter values that would deliver maximum exergetic efficiency for desired value of temperature rise. Design procedure has also been discussed to evaluate the optimum parameters with respect to operating conditions. Keywords: Solar thermal collector, Jet impingement, Exergy, Heat transfer, Optimizatio

Experimental investigation of an indirect solar dryer integrated with phase change material for drying valeriana jatamansi (medicinal herb)

In this study, an experimental investigation of an indirect solar dryer integrated with phase change material has been carried out for drying Valeriana Jatamansi. The experimentation has been performed under the climatic conditions of Himalayan region, Solan (latitude − 30.91°N, longitude − 77.09°E), Himachal Pradesh (India) in the month of October-November 2016. Paraffin RT-42 has been used as a phase change material in the dryer. Using this system, the moisture content of rhizomes reduced from 89% to 9% in 5 days as compared to heat pump drying and shade drying, which took 8 days and 14 days, respectively. Results of present study infer that the drying time using phase change material in this setup has reduced by 37.50% and 64.29% when compared to heat pump drying and shade drying, respectively. The dried rhizomes obtained are of superior quality in terms of colour, texture, aroma and bio-medical constituents. Analyses show that by using present setup, total valepotriates obtained were 3.47% as compared to traditional shade drying which yield 3.31%

Application of silver nanoparticles synthesized from Raphanus sativus for catalytic degradation of organic dyes

Biosynthesis of metal nanoparticles is gaining more importance owing to its simplicity, economical, sustainable route of synthesis of nanoparticles and ecofriendliness. Based on the search to improve and protect the environment by decreasing the use of toxic chemicals and eliminating biological risks in biomedical applications, the present article reports an environment friendly and unexploited methods for biofabrication of silver nanoparticles (AgNPs) using Raphanus sativus leaf extract. The synthesized AgNPs were characterized by UV-vis spectroscopy and transmission electron microscopy (TEM). The absorption spectrum of the dark brown color silver colloids showed a single and prominent peak at 431nm, indicating the presence of AgNPs. Further, catalytic degradation of methylene blue (organic dye) by using AgNPs was measured spectrophotometrically. The results revealed that biosynthesized AgNPs was found to be impressive in degrading methylene blue and can be used in water purification systems

Experimental investigation of effect of flow attack angle on thermohydraulic performance of air flow in a rectangular channel with discrete V-pattern baffle on the heated plate

In this work, the effect of angle of attack ( α a ) of the discrete V-pattern baffle on thermohydraulic performance of rectangular channel has been studied experimentally. The baffle wall was constantly heated and the other three walls of the channel were kept insulated. The experimentations were conducted to collect the data on Nusselt number ( N u b ) and friction factor ( f b ) by varying the Reynolds number ( Re ) = 3000–21,000 and angle of attack ( α a ) from 30° to 70°, for the kept values of relative baffle height ( H b / H ) = 0 . 50 , relative pitch ratio ( P b / H ) = 1 . 0 , relative discrete width ( g w / H b ) = 1 . 5 and relative discrete distance ( D d / L v ) = 0 . 67 . As compared to the smooth wall, the V-pattern baffle roughened channel enhances the Nusselt number ( N u b ) and friction factor ( f b ) by 4.2 and 5.9 times, respectively. The present discrete V-pattern baffle shapes with angle of attack ( α a ) of 60° equivalent to flow Reynolds number of 3000 yields the greatest thermohydraulic performance. Discrete V-pattern baffle has improved thermal performance as compared to other baffle shapes’ rectangular channel

Application of silver nanoparticles synthesized from

Biosynthesis of metal nanoparticles is gaining more importance owing to its simplicity, economical, sustainable route of synthesis of nanoparticles and ecofriendliness. Based on the search to improve and protect the environment by decreasing the use of toxic chemicals and eliminating biological risks in biomedical applications, the present article reports an environment friendly and unexploited methods for biofabrication of silver nanoparticles (AgNPs) using Raphanus sativus leaf extract. The synthesized AgNPs were characterized by UV-vis spectroscopy and transmission electron microscopy (TEM). The absorption spectrum of the dark brown color silver colloids showed a single and prominent peak at 431nm, indicating the presence of AgNPs. Further, catalytic degradation of methylene blue (organic dye) by using AgNPs was measured spectrophotometrically. The results revealed that biosynthesized AgNPs was found to be impressive in degrading methylene blue and can be used in water purification systems