Summary The drying needs of agricultural, industrial process heat requirements and for space heating, solar energy is one of the prime sources which is renewable and pollution free. As the solar energy is inconsistent and nature dependent, more often there is a mismatch between the solar thermal energy availability and requirement. This drawback could be addressed to an extent with the help of thermal energy storage systems combined with solar air heaters. This review article focuses on solar air heaters with integrated and separate thermal energy storage systems as well as greenhouses with thermal storage units. A comprehensive study was carried out in solar thermal storage units consisting of sensible heat storage materials and latent heat storage materials. As the phase change heat storage materials offer many advantages over the sensible heat storage materials, the researchers are more interested in this system. The charging and discharging characteristics of thermal storage materials with various operational parameters have been reported. All the possible solar air heater applications with storage units have also been discussed.

Li-ion batteries play a vital role in electromechanical devices. The heat load on such batteries varies with time and application which falls as high-temperature rise and it causes severe damages on a device and reduces the life cycle. It will be a big challenge in future decades of electronic devices and the electric car revolution. To overcome such difficulties, this work is considered for thermal management of small Li-ion batteries to check the possibilities through the micro heat pipe. Due to the high impact of Nanotechnology in heat transfer science, Acetone, De-ionized water, and Tetrahydrofuran fluids are blended with Graphene Oxide Nanoparticles to prepare the Nanofluids by ultrasonic method. Here, Tetrahydrofuran is a new combination of Nano-working fluid and not addressed by pre-researchers. Tetrahydrofuran-graphene Nanofluid provides 61% of improved thermal conductivity than the other two fluids which accelerates the heat transfer rate with reduced thermal resistance in the range of 0.09- 0.640C/W. To validate the experimental results, a real-time study has been done on Li-ion batteries for a day and ensured the reduction of overheat issues. Hence, the present work will support the Li-ion battery to work in an optimal temperature range in a new way of micro heat pipe with Nanofluid.

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The research article presented here mainly focuses on the influence of pre and post-injection (split in to three injections) technique that was used to improve the ethanol fuel combustion in compression ignition mode (CI), with and without zirconia surface coating. Combustion simulation results and experimental results were investigated and compared with different experimental conditions. This research was used (95% Ethanol +5% water) as a fuel in a four stroke single cylinder variable compression ratio (VCR) engine. The VCR engine was used to optimize compression ratio (28.8:1) and conducted various experiments. Performance and exhaust emissions of NOx, CO and HC were compared with ethanol fuel split injection mode, single injection mode and diesel fuel mode. Brake thermal efficiency of pre and post injection mode was better than direct injection (DI) ethanol mode. The VCR engine operating with ethanol fuel split injection mode showed peak brake thermal efficiency (BTE) of 29%, which is nearly operating range in the baseline diesel engine. Ethanol fuel was mixed with 3% castorene R40 (lubrication oil) oil by volume due to fully soluble in alcohol fuels. It was used both air and liquid cooled engines running on methanol and ethanol fuel. Pre and post ethanol injection mode was 54.4 % reduction of Oxides of nitrogen (NOx) compared with single injection mode of operation. In comparison of diesel mode operation with zirconia coating was 3.8% increased than without coating.