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Currently, the vehicle industry is confronted with issues such as the depletion of fossil resources, an increase in crude oil costs, and stricter emission regulatory standards. In this scenario, the use of viable alternatives to diesel as a fuel is necessary. This study discusses the combined effects of injection time and exhaust gas recirculation (EGR) on neat algal biodiesel-powered diesel engines. The transesterification technique was used to extract algal oil methyl ester (AOME), and the majority of the fuel qualities of AOME were quite comparable to diesel. The practicality of neat AOME for diesel engines operating at varied injection timings such as 19º BTDC, 23º BTDC, and 27º BTDC was investigated. The results of the tests revealed that advanced injection timing has a 3.02% higher BTE than standard fuel injection timing at maximum load for the AOME. Compared to other injection timings at full load, the neat AOME at 27º BTDC has better combustion characteristics and lower exhaust emissions. At full load, however, NOx emissions were higher. NOx emission was reduced by 35.24% when AOME was burned at 27º BTDC combined with 10% exhaust gas recirculation (EGR) compared to 27º BTDC without EGR. [ABSTRACT FROM AUTHOR]

An existing diesel engine was fitted with a common rail direct injection (CRDi) facility to inject fuel at higher pressure in CRDi mode. In the current work, rotating blades were incorporated in the piston cavity to enhance turbulence. Pilot fuels used are diesel and biodiesel of Ceiba pentandra oil (BCPO) with hydrogen supply during the suction stroke. Performance evaluation and emission tests for CRDi mode were carried out under different loading conditions. In the first part of the work, maximum possible hydrogen substitution without knocking was reported at an injection timing of 15° before top dead center (bTDC). In the second part of the work, fuel injection pressure (IP) was varied with maximum hydrogen fuel substitution. Then, in the third part of the work, exhaust gas recirculation (EGR), was varied to study the nitrogen oxides (NOx) generated. At 900 bar, HC emissions in the CRDi engine were reduced by 18.5% and CO emissions were reduced by 17% relative to the CI mode. NOx emissions from the CRDi engine were decreased by 28% relative to the CI engine mode. At 20%, EGR lowered the BTE by 14.2% and reduced hydrocarbons, nitrogen oxide and carbon monoxide by 6.3%, 30.5% and 9%, respectively, compared to the CI mode of operation. [ABSTRACT FROM AUTHOR]