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Stringent emission regulations and the depletion of conventional fuel sources drive research on green fuels, additives, and the optimization of fuel injection and exhaust gas recirculation. This study analyzes the impact of butanol additives in diesel and cashew shell liquid biodiesel (CSLB) blends under optimal operating conditions. CSLB was produced with an 85.43% yield from waste cashew nut shell liquid under optimal conditions: a methanol/CSL molar ratio (MR) of 20:1, a process temperature (PT) of 70 °C, and a 4 wt% industrial waste-derived heterogeneous catalyst (IC), using the desirability function approach in the RSM-CCD model. The catalyst was characterized using XRD, FTIR, and BET analyses to confirm its catalytic activity. Engine performance improvements were achieved with specific modifications, including 4° CA timing retardation, 15% split injection, and a 20% exhaust gas recirculation rate when using CSLB blends. In common rail direct injection (CRDI) experimental investigations, diesel and CSLB blends were combined with butanol additives (2.5%, 5%, and 10%) and compared to the baseline test. Incorporating 10% butanol, with its higher latent heat, resulted in a lower combustion temperature, reducing NO x emissions by 47.09% in CSLB10. Additionally, the additive’s lower viscosity and higher oxygen content enhanced atomization, reducing CO (33%) and smoke (23.02%) emissions. However, a slight increase in CO 2 (8.92%) and a decrease in HC emissions (27.14%) were observed in CSLB10. Improved combustion characteristics, reflected in higher peak pressure and heat release rate, resulted in a 4.75% increase in brake thermal efficiency and a 13.92% reduction in brake-specific energy consumption compared to ideal conditions. Overall, this study explores the impact of butanol additives on the performance and emissions of CRDI engines fuelled with CSLB blends derived from waste cashew nut shell liquids, providing insights for sustainable fuel optimization.

This study explores the impact of compression ratio (CR) and fuel blends on the combustion properties of a diesel engine fueled by conventional diesel and biodiesel derived from Moringa oleifera. The research was conducted on a single-cylinder diesel engine with variable compression ratio (VCR) and common rail direct injection (CRDI), utilizing diesel and Moringa oleifera biodiesel blends MB10, MB20, and MB30. The experimental conditions included varying the CR between 15:1 and 18:1, maintaining an injection timing of 23°before top dead center, injection pressure set at 600 bar, and an engine speed of 1500 rpm under 100% load. The findings revealed that increasing the CR raises cylinder pressure (CP), cumulative heat release rate (CHRR), and rate of pressure rise (ROPR) for all the tested fuel blends. Notably, the diesel exhibited the highest CP of 70.83 bar, CHRR of 1.36 kJ, and ROPR of 6.42 bar/°CA (degree per crack angle) at a CR of 18:1. Among the biodiesel blends, MB30 showed the highest CP of 69.21 bar, while MB10 displayed highest CHRR and ROPR of 1.5 kJ and 6.17 bar/°CA, respectively. Furthermore, the net heat release rate (NHRR) and mean gas temperature (MGT) decreased with rising CR for all tested fuels. At a lower CR of 15:1, the diesel showcased the highest NHRR and MGT of 69.75 J/°CA and 1303.69 °C, respectively, whereas, in the case of biodiesel blends, MB20 demonstrated the highest values of 67.53 J/°CA and 1287.39 °C, respectively, at the same CR. Meanwhile, the ignition delay (ID) and combustion period diminish with a rise in the CR for all tested fuel blends. At a higher CR of 18:1, the minimum ID and combustion duration for diesel were reported as 17°CA and 15°CA, respectively. For the biodiesel blends, MB10 and MB30 showed a minimum ID of 16°CA, while MB10 and MB20 exhibited minimum combustion duration of 15°CA at the same CR.

Limited fossil fuel reservoir capacity and pollution caused by them is the big problem in front of researchers. In the present paper, an attempt was made to find a solution to the same. The conventional fuel injection system was retrofitted with a simple version of the common rail direct injection system for the small diesel engine. Further, the effect of injection system parameters was observed on the performance and emission characteristics of the retrofitted common rail direct injection diesel engine. The parameters such as injection pressure, the start of pilot injection timing, the start of main injection timing and quantity of percentage fuel injection during the pilot and main injection period were considered for experimental investigation. It was observed that all the evaluated parameters were found vital for improving the engine’s performance and emission characteristics. The retrofitted common rail direct injection system shows an average 7% rise in brake thermal efficiency with economic, specific fuel consumption. At the same time, much more reduction in hydrocarbon, carbon monoxide and smoke opacity with a penalty of a slight increase in nitrogen oxides.

This paper demonstrates the study of performance, combustion and emission characteristics of a common rail diesel injection (CRDI) engine with the influence of exhaust gas recirculation (EGR) (5, 15 and 25%) at various fuel injection pressures (400, 500 and 600 bar) under the effective load conditions (0, 25, 50, 75 and 100%). The experiments were carried out in a controlled manner using the CRDI engine fuelled with 80% (D80) diesel (98% purity) blended with 20% (B20) tallow biodiesel. The engine has been operated at a rated speed of 1500 rpm on all load conditions, fuel injection timings of 10°, 15° and 20° bTDC, fuel injection pressures of 400, 500 and 600 bar, respectively. Combustion-influenced performance characteristics such as variation of in-cylinder pressure and net heat release rate in J deg−1 are also studied with the above operating conditions. It was observed that the usage of 20% biofuel blend shows considerable improvement in combustion, and it further enhances with an increase in the injection pressures. Besides, EGR (up to 25%) reduced significant pollutants at higher operating pressures (600 bar) at higher load conditions. It was also observed that CO2 emission increased with increase in the % EGR with an increase in the load conditions. However, for CO emission increased up to 50% load condition and subsequently tends to decrease due to improved combustion at higher load; hence higher temperature. NOx, smoke opacity continue to increase with the increase in pressure and the percentage increase in EGR due to its attainment of adiabatic temperature, which leads to the pathway for the Zeldovich mechanism. The present work shows light on the usage of tallow methyl ester produced from the wastes in the tannery industry as alternate biofuel operating the CRDI engines without compromising its combustion and emission characteristics to deliver the same power as petro-diesel.

For improving engine performance, combustion and controlling emissions from compression ignition (CI) engines, common rail direct injection (CRDI) technology offers limitless possibilities by controlling fuel injection parameters such as fuel injection pressure, start of injection (SOI) timing, rate of fuel injection and injection duration. CRDI systems available commercially are quite complex and use a large number of sensors, hardware and analytical circuits, which make them very expensive and unfeasible for cheaper single cylinder engines, typically used in agricultural sector and decentralized power sector. This paper covers experimental investigations of a simpler version of CRDI system developed for a constant-speed, single-cylinder engine. Modifications in the cylinder head for accommodating solenoid injector, designing injector driver circuit and development of high pressure stage controls were some of the engine modification and development tasks undertaken. SOI timing is an important parameter for improving engine’s combustion characteristics. SOI timings were varied between 25° and 40° BTDC for investigating engine’s performance, emissions and combustion characteristics. Advanced fuel injections showed higher heat release rate (HRR), cylinder pressure and rate of pressure rise (RoPR) because of relatively longer ignition delay experienced. Lowest brake specific fuel consumption (BSFC) was obtained for 34° CA BTDC SOI. Reduction in engine out emissions except NO x was observed for advanced fuel injection timings for this newly developed CRDI system.