Ravishankar Sathyamurthy

Experimental investigation of a semi circular trough solar water heater

This paper studies the experimental analysis of a semi circular trough absorber solar water heater with baffles for improving the outlet water temperature. To increase the contact time of water with solar radiation and decreasing the flow rate of water baffles are kept in the absorber at a distance of 0.1 m. Studies are conducted for different flow rates of water in the absorber and flow rates increased by 2, 4, 8 and 16 times the base value of 0.133 kg/min. Results show that there is an increase in the outlet water temperature by 66.5 and 50°C with respect to inlet temperature during summer and winter, respectively, with an average inlet temperature of 34°C at minimum mass flow. The maximum water temperature during summer and winter conditions are found as 65 and 60°C respectively. Also, results show that the percentage increase in temperature of outlet water and average water temperature depends on solar intensity.

Geometrical variations in solar stills for improving the fresh water yield—A review

AbstractWater consumption by humanity is one of the major yardsticks to assess its civilization. Humans depend on groundwater sources for drinking. Some of these underground water sources cannot be used for drinking due to pollution. To solve the issues related to drinking water, several methods are employed, and a promising one is solar desalination. This paper communicates a review of different geometrical shapes of solar still. The present study concludes that the geometry in the solar still significantly influences the yield of fresh water.

Theoretical analysis of a triangular pyramid solar still integrated to an inclined solar still with baffles

Abstract This paper presents the theoretical analysis of a triangular pyramid solar still integrated to an inclined solar still with baffles. The performance of the solar still depends on water mass inside the basin. The yield of triangular pyramid solar still is increased by integrating it to an inclined solar still with baffles. Analytically, the water mass inside the basin is increased from 20 to 100 kg. Theoretical results show that the increase in water mass decreases the yield from 6% to 46% during the daytime, whereas due to thermal energy storage at higher mass, the yield during the nighttime increases from 46% to 86% with integration. Similarly, a triangular pyramid solar still is theoretically analysed for its performance.

Experimental Validation of Fresh Water Production Using Triangular Pyramid Solar Still with PCM Storage

In the study work effect of PCM on the triangular pyramid solar still was experimentally investigated for the climatic condition of Chennai. Experimental studies were conducted and the use of PCM on storage was compared with a solar still without PCM and the PCM used is paraffin wax. The latent heat energy storage is increased with the use of paraffin wax while the energy stored is utilized during the absence of solar radiation by rejecting its heat through the basin to water for further evaporation. The temperatures of various elements of the solar still were measured using a thermocouple. Results show that there is an increase in productivity of 20% when compared to the solar still without PCM.

Enhancing the thermal performance of Al2O3/DI water nanofluids in micro-fin tube equipped with straight and left-right twisted-tapes in turbulent flow regime

ABSTRACT This article communicates the thermal performance, heat transfer rate, and friction factor of Al2O3/DI water nanofluids at different concentrations in a micro-finned tube with tube helical inserts for different twist ratios. The thermal performance, heat transfer coefficient, and friction of the present study is also compared with a plain tube for validation. From the study, it is identified that the micro-finned tube with tube insert performance is higher as compared with a plain tube. Similarly, an empirical relation for Nusselt number (Nu) and friction factor (f) is estimated for straight twisted tube and left-right combination. The deviation between experimental and theoretical values for left-right twist and straight twist is found as 3 and 7% for Nusselt number and 7 and 9% for friction factor, respectively. Similarly, while analyzing the thermal performance, it was found that the maximum performance achieved was with a micro-fin tube with left-right twist with nanofluid concentration of 0.2%.

Economic and exergy investigation of triangular pyramid solar still integrated to inclined solar still with baffles

ABSTRACT This paper presents the detailed exergy and economic investigation of triangular pyramid solar still under passive and active mode of operation. For validation, experiments were carried out at different water depth maintained inside the basin under a continuous flow of water from an inclined solar still. Results confirm that the effect of integration rises the exergy efficiency during the offshine period, whereas during the sunshine hours the exergy efficiency decreases when the maintained the depth of water inside basin decreases. Similar study on economic analysis shows that the net pay back period increases from 5.6 to 11.4 with an increase in the water depth at an average selling price of water Rs 5/kg in a standalone triangular pyramid solar still.

Effect of forced cover cooling technique on a triangular pyramid solar still

Abstract In the present study a triangular pyramid solar still is theoretically analysed by flowing air over the entire surface of the glass from the top to analyse the improvement in yield of fresh water. The effect of water mass and wind velocity was theoretically analysed. The results show that there is a significant improvement in the yield of fresh water to about 10.1 kg/m2 with a maximum velocity of air (U = 40 m/s) at a least water mass of 20 kg inside the basin. For practical cases the yield of fresh water depends on naturally occurring wind velocity and the results show that the improvement in yield is 104% with an increase in velocity from 0.5 to 4 m/s.

Effects of electric potential, NaCl, pH and distance between electrodes on efficiency of electrolysis in landfill leachate treatment

ABSTRACT This study investigated the effects of different parameters on the removal efficiencies of organic and inorganic pollutants in landfill leachate treatment by electrolysis. Different parameters were considered such as the electric potential (e.g., 24, 40 and 60 V), hydraulic retention time (HRT) (e.g., 40, 60, 80, 100 and 120 min), sodium chloride (NaCl) concentration (e.g., 1, 3, 5 and 7%), pH (e.g., 3, 7 and 9), electrodes materials [e.g., aluminum (Al) and iron (Fe)] and distance between electrodes (e.g., 1, 2 and 3 cm). The best operational condition of electrolysis was then recommended. The electric potential of 60 V with HRT of 120 min at 5% of NaCl solution using Al as anode and Fe as cathode (kept at a distance of 3 cm) was the most efficient condition which increased the removal efficiencies of various parameters such as turbidity, salinity, total suspended solids (TSS), total dissolved solids (TDS), biochemical oxygen demand (BOD), chemical oxygen demand (COD) and heavy metals (e.g., Zn and Mn). The higher removal percentages of many parameters, especially COD (94%) and Mn (93%) indicated that the electrolysis is an efficient technique for multi-pollutants (e.g., organic, inorganic and heavy metals) removal from the landfill leachate.

Investigation on LPG-Biogas Blends in Spark Ignition Engine

Internal combustion engines normally operate with the nonrenewable sources such as petrol and diesel, which are diminishing at a faster rate. To avoid these problem alternative sources of energy must be opted for the operation of internal combustion engines. In this work biogas is selected as an alternative source of energy for the working of internal combustion engines but possess some limitations due to its high auto ignition temperature and high CO2 content in it. To overcome the limitations biogas is blended with LPG at different proportions of 5%, 10%, 15% are done. The modification of the internal combustion engine is performed to convert it into a gas engine and the tests are conducted on the modified engine with different proportions of blending at various loads. Based on the results of the test conducted the performance characteristics are analyzed.

Passive solar still: recent advancements in design and related performance

Present review paper mainly focuses on different varieties of solar stills and highlights mostly the passive solar still with advanced modifications in the design and development of material, single and multi-effect solar still with augmentation of different materials, energy absorbing, insulators, mechanisms of heat and mass transfer to improve the loss of heat and enhance the productivity of solar still. The cost-benefit analysis along with the progressive advancement for solar stills is the major highlights of this review. To increase the output of solar still nowadays, applications of advance modifications is one of the promising tools, and it is anticipated that shortly more vigor will be added in this area with the modifications in designs of solar stills.