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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]

In the current work, n-butanol-diesel blends were tested on a small size agriculture-based compression ignition (CI) engine. Taguchi analysis was carried out to identify the optimum blending ratio and engine operating parameters. Experiments were conducted with n-butanol/diesel blends (10–20% by volume) by varying compression ratio (CR) (17.5–19.5), injection timing (21–25 CA btdc) and injection pressure (200–220 bar). The 20% n-butanol/diesel blend (BU20) showed better results of performance and emissions at increased CR under similar operating conditions. When engine was fueled with BU20, reduction in Smoke, NOx (Nitrogen-oxides) and CO (Carbon-monoxide) were observed to be 49.03%, 13.68% and 5.88%, respectively, in comparison to diesel. However, HC (Hydrocarbons) were found to be higher by 11.76% for BU20 as compared to diesel. [ABSTRACT FROM AUTHOR]

The continuous rise in environmental pollution has attracted the attention of researchers in clean alternative fuels for internal combustion engines. In the present study, experimental investigations were carried out on a small size, modified, variable compression ratio diesel engine with n-butanol-diesel blends (10–25% by volume) as fuel to determine the optimum blending ratio and operating parameters for reduced emissions. Full Factorial design approach was employed for modeling and analysis of experimental data. The experiments were planned and performed in three distinct phases at a constant speed of 1500 rpm and at varying engine load (12, 16, 20 and 24 Nm). The engine loads, blending ratio, compression ratio, injection timing and injection pressure were taken as input parameters and their effects on engine performance and emissions were investigated experimentally and analytically. In the modeling work, reduced quadratic and cubic prediction models were developed, checked for normality and homogeneity and parameters were optimized for desired responses. The optimum results were observed with twenty percent n-butanol-diesel blend (B20) at a higher compression ratio of 19.5 as compared to 18.5 for diesel under similar operating conditions. Brake thermal efficiency improved by 5.54% and smoke & nitrogen oxides decreased by 59.56% & 15.96% respectively for B20 in comparison to diesel at full load condition. Results of the study show that n-butanol-diesel blend is a potential fuel to reduce emissions from diesel engines with improved performance. A close match between experimental results and prediction results reveals that the developed models can be used with adequacy to optimize similar type of diesel engines using n-butanol-diesel blends. [ABSTRACT FROM AUTHOR]