The main reason for the limited usage of biodiesel is it tends to oxidize when exposed to air. It is anticipated that the addition of an antioxidant along with graphene nano particle improves combustion of diesel-biodiesel blend. In the present research biodiesel made from the transesterification of waste cooking oil is used. Three synthetic antioxidants butylated hydroxytoluene (BHT), 2(3)-t-butyl-4-hydroxyanisole (BHA) and tert butylhydroquinone (TBHQ) along with 30 ppm of graphene nano particle were added at a volume fraction of 1000 ppm to diesel–biodiesel blends (B20). The performance and emission tests were performed at constant engine speed of 1500 rpm. Because of the inclusion of graphene nano particles, surface area to the volume ratio of the fuel is augmented enhancing the mixing ability and chemical responsiveness of the fuel during burning causing superior performance, combustion and emission aspects of compression ignition engine. The results revealed that there was a slight increase in brake power and brake thermal efficiency of about 0.29%, 0.585%, 0.58% and 6.22%, 3.11%, 3.31% for B20GrBHT1000, B20GrBHA1000 and B20GrTBHQ1000, respectively, compared to B20. Additionally, BSFC, HC and NO_x emissions were reduced to considerable levels for the reformed fuel.

Combustion of biodiesels has inherent problems due to their high viscosity and low volatility. This paper relates the modification of engine combustion chamber design, for inducing turbulence to improve the combustibility of combustible mixture. A survey of literature shows that experimental studies have not been done on a tri-chambered piston for evaluating influence on the performance and emission characteristics using diesel blends as well. The objective of this work is to study the effect of combustion chamber geometry and injection pressure on performance and emissions of a biodiesel (Jatropha) fuelled multi-chambered piston diesel engine. The performance and emission characteristics were studied and it has been noticed that for the engine under consideration 200 bar injection pressure gives optimum performance.

Pilot-fueling and nozzle-injection pressure are significant injection parameters, and they have significant impacts on modern vehicles for enhancing the engine output, in addition to meeting rigorous tailpipe-exhaust emission standards. In this current work, the influence of the pilot-fueling pressure and nozzle-opening pressure (NOP) on the engine performance and tailpipe outcomes from a compression-ignition (CI) engine at a higher injection pressure and varying load conditions was investigated using a waste cooking oil (WCO) biodiesel (B20). The experiments were executed in a high-pressure CRDi-fitted diesel engine at the start of pilot fueling (SOPF) (timing: 23° bTDC), and at the start of the main fueling (SOMF) (timing: 33° bTDC). The results showed that the combined influence of the pilot-fueling and nozzle-opening pressure induced a remarkable enhancement in the BTE, by 25.13%, and the BSFC decreased by 13.88%, compared with diesel at 10% pilot fueling. Carbon monoxide, hydrocarbon, and smoke emissions were drastically reduced for the higher pilot-fueling quantity by 21.05%, 16.66%, and 33.10%, respectively, compared with the diesel at 10% pilot fueling. With the implementation of the pilot-fueling strategy, there is no effect on the NOx reduction.

The ever-increasing demand for transport is sustained by fossil fuel-based internal combustion (IC) engines fitted with catalytic converters (CCs) while alternative options and fuels are still emerging. Biodiesel seems to be a potential alternate to diesel, but the formation of NO_x and smoke are major issues. This study aimed to explore the effect of B100 Pongamia biodiesel on the performance of CCs and to assist the designers of compression ignition engines. This study included a comparison of deposits on the catalytic converter (CC) in the cases of diesel fuel and biodiesel. Forensic examination of the spent CCs after 250 h was performed by characterization using SEM/EDS. The amount and composition of the deposits were compared for the diesel and biodiesel, and the effectiveness of the CC. The study revealed that the efficiency of the CC increased in biodiesel. The amount of soot and deposits was greater at the engine side of the spent CC with diesel, including the atomic percentage (At. %) of C, while the minimum deposits and C At. % in the spent CC were at the exhaust side with biodiesel. Oxygen content in the deposits was greater in biodiesel. The efficiency and effectiveness of the CC increased with the biodiesel.