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Water-diesel emulsion fuel has been found as a prominent alternative fuel by various researchers. Alike this technology, cow-urine (Bos indicus urine) emulsified diesel fuel (GMD emulsion) has been explored in this study. Making of homogeneous and stable emulsion is a crucial aspect in this approach while maintaining the diesel standards. Hence, the applicability of this fuel has been examined based on physicochemical properties for diesel engine application. The stability was assessed by creaming index, droplet size, Pdi, and interfacial tension. The minimum droplet size (278 nm) and 0.282 Pdi was obtained with 5.72 HLB value, 4% (v/v) surfactant, and 10% (v/v) of cow-urine through ultra-sonication. The optimized 10% GMD emulsion was found stable for more than 80 days. Viscosity and density of the fuel got increased with cow-urine and surfactant; however, they found within the standard limits. The physicochemical analysis exhibited the feasibility of the GMD emulsion for diesel engine application. [ABSTRACT FROM AUTHOR]

Out of various strategies to extenuate the diesel engine emissions, use of water-blended diesel fuel in emulsified form is found to be a prominent option. The studies carried out by various researchers give quite inconsistent results for optimum water concentration, surfactant concentration, and HLB value. An effort has been made in this paper to analyze this inconsistency of water concentration and surfactant for engine emissions and performance along with the effect of compression ratio. The work has been carried out on a non-road, constant rpm, VCR (variable compression ratio) diesel engine. Different emulsions of 5%, 10%, 15%, and 20% water-in-diesel with 3% emulsifier concentration were tested on the diesel-optimized engine at CR 21. The results showed that emulsion of 15% water-in-diesel is optimal on the basis of emissions and performance. Further, the selected 15% emulsion is tested with 4% emulsifier concentration. It improved the stability of emulsion and performance of the engine with slight adverse effects on the NOx emissions. Then, emulsion with 4% surfactant and 15% water is tested to determine optimum compression ratio for emulsified fuels. CR 20 is found in optimum. Remarkably 9.28% improvement in BTE is observed reaching up to 23.89% as compared to 21.86% with bare diesel. 25.1% reduction in NOx and more than 50% reduction in smoke is observed. Overall, it is concluded that the water-blended diesel emulsion could serve as a fuel-efficient cleaner combustion technology and needs to be standardized. Abbreviations HLB: Hydrophile–Lipophile Balance; Cv: Calorific Value; W/D: Water in Diesel; PM: Particulate matter; RPM: Rotation per minute; HC: Hydrocarbon; CR: Compression Ratio; EGT: Exhaust Gas Temperature; BTE: Brake Thermal Efficiency; NOx: Oxides of Nitrogen; BSFC: Brake specific fuel consumption [ABSTRACT FROM AUTHOR]

Aligning to water-in-diesel emulsion technology, a newer work has been proposed in this study by introducing gomutra-in-diesel emulsion (GMD emulsion) fuel for application in CI engine. Experimental investigations have been performed in this study for ignition delay and combustion duration to understand the underlying mechanisms of combustion with this fuel. The complete work has been performed over a variable compression ratio (VCR) stationary diesel engine. Emulsions of different gomutra-in-diesel (5%, 10%, 15% and 20%) concentrations were taken for the study. The ignition delay was found to be 24°, 27°, 29°, 32°, and 34° crank angle (CA) with diesel, 5%, 10%, 15%, and 20% water-in-diesel emulsions respectively. The effect of injection timing on the engine performance was also analysed. It was observed that the combustion duration got decreased by a maximum of 12 degrees CA with 20% GMD emulsion. It is estimated that after the optimisation of other engine parameters like injection pressure and compression ratio, the performance of the engine could further be improved. [ABSTRACT FROM AUTHOR]

The rapid depletion of conventional fuel reserves and the increase in environmental pollution prompted the search for a sustainable energy solution. Biodiesel is one of the most promising energy substitutes with similar properties as conventional diesel fuel. Surplus availability of palm oil makes it suitable for biodiesel production. Due to the lack of availability of review articles that cover the entire process of palm biodiesel production and its optimum use in diesel engines, the authors were motivated to write this article. Cultivation parameters of palm trees, extraction of oil, and physicochemical properties of palm oil–based biodiesel are explained in this review. The production of palm biodiesel from raw oil can be done through pyrolysis, micro-emulsification, blending, hydro-esterification, and transesterification processes. For high biodiesel yield and less cost of operation, the transesterification method is adopted. The performance and emission parameters of diesel engines that operated on palm biodiesel and its blends are also explained. There is a decrease in brake thermal efficiency and an increase in brake-specific fuel consumption observed with the use of palm biodiesel in diesel engines. A reduction in CO and HC emissions and an increase in NOx emissions are found due to the oxygenating nature of palm biodiesel. This article provides the scientific approach to find out the optimum parameters for palm biodiesel production and its efficient use in compression ignition engines. [ABSTRACT FROM AUTHOR]

This study investigates the characterization of the hydroxy-diesel fueled compression ignition engine under dual fuel (DF) mode on a stationary modified engine. Hydroxy gas (HHO) is supplied along with diesel at three different flow rates of 0.25, 0.50, and 0.75 lpm. A significant reduction in emission parameters was obtained in carbon monoxide, unburnt hydrocarbon and smoke emission as ~58%, ~60%, and ~49%, respectively under the DF mode (at 0.75 lpm HHO and 10 kg load). However, a slight increment in nitrogen oxides (NO X) emission is observed due to the O 2 contents in HHO gas. It increases the reaction temperature and results in increasing the NO X emission. The brake thermal efficiency and brake specific energy consumption also improved and found to be ~6.5% and ~6% at the optimized condition. Combustion analysis shows the rate of pressure rise increased due to quicker combustion and decreased combustion duration. A numerical simulation has been performed to optimize the engine load and HHO flow rate using the Hybrid Entropy-VIKOR technique. In addition, a good agreement has been found between simulation and experimental values for performance and emission parameters. The results can be further improved by optimizing the engine operating parameters, i.e., injection pressure, compression ratio, and injection timing in the near future. Overall it can be concluded the HHO can be considered as a prominent alternative fuel for the CI engine with increased efficiency and lower emissions. Image 1 • Engine performance parameters (BTE and BSEC) improved with the hydroxy energy share. • Significant reduction in HC, CO, and smoke emission was observed with the HHO addition. • ROPR, in-cylinder MGT, and NHRR improved for D+0.75HHO mixture. • The engine operating parameters were optimized using the hybrid Entropy-VIKOR approach. [ABSTRACT FROM AUTHOR]

Latest research on fuels focused on exploring better alternatives for compression ignition engines. A large number of studies reported that the properties of biodiesel are comparable with traditional diesel fuel, which makes it a suitable alternative source of energy. Among various available feedstocks, waste cooking oil is considered as the most viable source for biodiesel production. Apart from being economical, it also reduces waste disposal issues. High free fatty acids and water content in waste cooking oil cause the production of biodiesel difficult. In order to overcome this difficulty, two-step transesterification method is preferred for commercial-scale biodiesel production. Several factors like catalyst concentration, alcohol to oil molar ratio, reaction temperature, and time of reaction affect the yield of biodiesel. This article provides a comprehensive review of biodiesel production from waste cooking oil and its use in compression ignition engines. In this review, fatty acid composition, pre-treatment process, catalytic and non-catalytic approaches of biodiesel production with their advantages and limitations are included. The effect of transesterification reaction parameters on biodiesel yield is also covered. The high viscosity of biodiesel than diesel fuel causes an increase in brake specific fuel consumption and a decrease in brake thermal efficiency of engines. Significant reduction in CO, HC, PM, and smoke emissions are identified; however, NO X and CO 2 emissions found increased due to the oxygenating nature of biodiesel. Overall, it could be concluded that biodiesel produced from waste cooking oil serves as a cleaner and economical alternative source of fuel for compression ignition engines. [Display omitted] • Approximately 30% of per capita edible oil consumption is generated as waste. • Two-step transesterification is the most efficient method for biodiesel production. • Yield of biodiesel is most influenced by the type of catalyst and its concentration. • Brake specific fuel consumption increases due to poor atomization of biodiesel. • CO, HC, PM, and smoke emissions from engine exhaust are reduced significantly. [ABSTRACT FROM AUTHOR]

• Classification of biodiesel generations on the basis of the type of feedstocks is covered. • Botanical description and growth condition requirements of jatropha are discussed. • Physicochemical properties and fatty acid profile of jatropha biodiesel are analyzed. • Production of biodiesel from jatropha oil with different techniques is summarized. • Performance and emissions characteristics of C.I. engine fuelled with jatropha biodiesel are reviewed. Due to limited reserves of conventional fossil fuels and their negative impact on global climate and human health, researches are focused to find the alternate energy substitute. Comparable properties of biodiesel make it one of the most promising alternatives of conventional diesel fuel. Jatropha curcas oil (non-edible oil) belongs to the second-generation of biodiesel. In this review, the physicochemical properties, fatty acids distribution, stability of jatropha oil are discussed in detail. The change in fatty acid profile affects the fuel properties, performance and emissions of diesel engines operated on jatropha biodiesel. Oxidation stability of jatropha biodiesel is poor due to the high amount of unsaturated fatty acids. Blending, thermal cracking, micro-emulsification, and transesterification are four basic approaches for production of biodiesel. Transesterification is the most adoptive method due to less expensive operation and high product yield. This article also highlighted the performance and emissions of compression ignition engines operated on jatropha biodiesel and its blends. The lower calorific value of jatropha biodiesel is responsible for the decrease in brake thermal efficiency and an increase in brake specific fuel consumption. High availability of oxygen in jatropha biodiesel reduces HC, CO, and PM emissions, while NOx emission increases significantly. This article provides the most of details of optimum parameters for jatropha biodiesel production and its efficient use in diesel engines. [ABSTRACT FROM AUTHOR]