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    Combined effects of nozzle hole variation and piston bowl geometry modification on performance characteristics of a diesel engine with energy and exergy approach
    (Elsevier Ltd., 2022) Praveena, V.; Leenus Jesu Martin, M.; Varuvel, Edwin Geo
    This experimental work aims to address the challenges of waste management. Biomass waste is converted into useful fuel and considered as a replacement to conventional fuel in CI engines. In this context, the grape marc and grape pomace are crushed and further processed to produce grapeseed oil. The grapeseed oil is further trans esterified to produce grapeseed seed oil methyl ester. The present study aims in examining the effect of varying piston shapes and nozzle profile on energy and exergy rates of a CI engine run with grapeseed oil methyl ester (GSME) blended with cerium oxide nano particles. The CeO2 nano particles were suspended in the base fuel at a concentration of 100 ppm and stability tests were conducted. The experiments were performed on a single cylinder, water cooled diesel engine with rated power of 5.2 kW. The research work includes two additional piston shapes namely, toroidal and shallow deep and two additional nozzle profiles viz. 4 hole and 5-hole nozzle. The hemispherical shape and 3-hole nozzle were considered as the standard one. Energy and exergy analysis were done on the experimental data to understand the exergy associated with cooling water, exhaust gas and unaccounted losses. The energy and exergy rates show that increase in nozzle hole number, decreases the destructive availability of the system. The exergetic efficiency of 32.8% is higher proving that toroidal shape and 5-hole nozzle profile is comparatively better and suitable for effective engine operation. HC, CO and smoke emissions reduced considerably by 14.4%–30% by the engine modification. Brake thermal efficiency was improved from 28.2% to 31.02% for CI engine with biodiesel. The paper addresses the gap in fuel modification clubbed with engine modification using biomass waste derived fuel. Exergy and energy analysis further add value to this current experimental work.
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    Combined effects of various strategies to curtail exhaust emissions in a biomass waste fueled CI engine coupled with SCR system
    (Elsevier B.V., 2021) Praveena, V.; Martin, M. Leenus Jesu; Geo, V. Edwin
    This study is an exhaustive investigation on engine performance and combustion features of a conventional diesel engine charged with biodiesel produced from biomass waste. Grapeseed oil methyl ester resulted in poor thermal efficiency with enormous quantity of harmful emissions. As an effort to reduce the engine pollutants, Grapeseed oil methyl ester was doped with zinc oxide nano particles, engine cylinder shape modification and exhaust gas recirculation method was used. Hydrocarbons, carbon monoxide and smoke emissions reduced considerably, whereas reduction in nitrogen oxide emissions was low. Selective catalytic reduction technique at optimized mass flow rate of aqueous urea solution minimized the nitrogen oxide emissions by 76.9% compared to grapeseed oil methyl ester without compromise in brake thermal efficiency.
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    Experimental assessment on the performance, emission and combustion characteristics of a safflower oil fueled CI engine with hydrogen gas enrichment
    (Elsevier Ltd, 2022) Praveena, V.; Joseph Shobana Bai, Femilda Josephin; Balasubramanian, Dhinesh; Devarajan, Yuvarajan; Aloui, Fethi; Varuvel, Edwin Geo
    Inducting hydrogen with biodiesel in a compression ignition (CI) engine contributes to improvising the performance characteristics of the engine and minimize long-term issues. Combustion of hydrogen along with intake air impacts positively in air quality by preventing the formation of toxic emissions like hydrocarbons (HC) and carbon monoxide (CO). The benefits of hydrogen such as good diffusion rate, lesser ignition energy and fast flame propagation rate promotes a more homogenously mixed air fuel ratio. This experimental work focuses on enhancement of the performance and combustion characteristics of a direct injection compression ignition (DICI) engine by enriching the biodiesel with various levels of hydrogen gas supplement at the intake manifold. The brake thermal efficiency of the engine with safflower oil biodiesel is 31.15 % which is far inferior to that of diesel with 34 %. As an effort to improve the performance characteristics of the CI engine, hydrogen gas is inducted at 4 %, 8 % and 12 % energy share. HC, CO and smoke emission decreases by 15.09 %, 34.6 % and 18 % respectively compared to neat biodiesel at full load of 5.2 kW. An opposite trend is observed in NOx emissions which are raised from 1650 ppm to 1852 ppm. A 12.2 % increase in NOx emissions are realized due to homogenous flammable mixture that combusts closer to Top dead center (TDC). The hydrogen enrichment with safflower oil biodiesel influences the combustion characteristics in a positive vein except for the NOx emissions, which could be minimized through the use of retrofit devices like selective catalytic reducer, diesel oxidation catalyst etc.
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    A systematic review on biofuel production and utilization from algae and waste feedstocks- a circular economy approach
    (Pergamon-Elsevier Science Ltd, 2024) Praveena, V.; Martin, Leenus Jesu; Matijosius, Jonas; Aloui, Fethi; Pugazhendhi, Arivalagan; Varuvel, Edwin Geo
    Energy demand on a global measure grows continuously due to increased population, industrialization and economic growth. Fossil fuel resources that are currently available are definitely not sufficient to meet the growing demand. In addition, the continuous emissions from automobiles and industrial sectors should be attended to so that a complete remedial and sustainable alternative for fossil fuels is obtained. The appropriate replacement for fossil fuel is biofuel, as they are renewable and eco-friendly. First generation and second generation biodiesel derived from various sources are extensively researched and experimented practically by the past researchers. This article summarizes a continuous and comprehensive assessment of different feedstocks needed for third and fourth generations of biodiesel. Various sources of feedstock, steps for biodiesel production, yield of biodiesel obtained through different methods, properties of biodiesel like fatty acid profile, density, viscosity, cetane number, flash point, cloud point, economic feasibility and considerations are also discussed. Third generation biodiesel like microalgae can be widely used in CI engines. It is observed that their performance and combustion analysis in a CI engine is determined by the physico chemical properties of obtained biodiesel and nature of feedstock. Species selection and cultivation methods of microalgae, future perspectives of cultivating techniques and lipid production are summarized in detail. Fourth generation biodiesel like solar fuels and synthetic biomass production are covered, though their application in various energy fields is still not revealed. The type of transesterification that best suits the free fatty acid profile of fuel is selected and other reaction parameters like reaction time, reaction temperature, catalyst quantity and oil methanol molar ratio are explained individually for third generation feedstocks. Proper adoption of suitable methods would help in yielding the maximum biodiesel. Future energy demand can be dealt with by the combination of various third and fourth generation oil feedstocks.