Diesel engines have extensive use in vehicles, power plants, and agriculture, but they pose significant challenges due to both regulated and unregulated emissions. As fossil fuel supplies diminish and pollution levels increase, it has become crucial to shift from conventional fuels to biodiesel and alternative additives. This experimental study investigates the emission and performance characteristics of a water‐cooled, three‐cylinder, four‐stroke compression ignition engine operating on blends of Jojoba methyl ester (JME) combined with additives such as carbon nanotube (CNT). JME was mixed with pure diesel in concentrations of 5% and 15% by volume, creating blends referred to as J5 and J15. CNT was added to these blends at a concentration of 20, 40, and 60 ppm. Emission and performance metrics were evaluated across engine speeds varying from 1200 to 2200 rpm. The findings revealed significant improvements, with brake thermal efficiency (BTE), brake power (BP), and torque increasing by 6.7%, 3.8%, and 3.8% respectively. A 2.6% reduction in brake‐specific fuel consumption (bsfc) was observed at 1600 rpm with the J5CNT60 blend. The introduction of Jojoba biodiesel into neat diesel resulted in reductions of 12.8%, 14.56%, 15.25%, and 7.27% in nitrogen oxide (NO _x ), carbon monoxide (CO), carbon dioxide (CO ₂ ), and unburned hydrocarbon (UHC) emissions, respectively. Although Jojoba biodiesel resulted in a slight increase in smoke opacity (SO) emissions by less than 1%, the addition of CNT led to a 2% decrease in SO emissions at 2000 rpm.

Adverse atmospheric conditions and health hazards originated due to the discharge of particulate matter (PM), hydrocarbons (HC), nitrogen oxides (NOx) and carbon monoxide (CO) are the fundamental challenges to the researchers working on diesel engine. The solution is to develop cleaner technologies to abate emissions from diesel engine exhaust. In this paper, a novel hybrid emission control unit composed of counter flow heat exchanger (HE), oil bath cleaning unit (OBCU) and exhaust gas recirculation (EGR), the combination abbreviated as HE-OBCU-EGR unit, was designed, fabricated and implemented on the exhaust manifold of Massey Ferguson (MF-260) tractor engine to reduce the regulated gaseous emissions. An experimental study was conducted to investigate the effects of HE-OBCU-EGR unit on the emissions of a four-stroke, three cylinder diesel engine equipped with an eddy-current dynamometer. The tests were conducted on engine speed of 1400 to 2000 rpm with an interval of 100 rpm at full load. The AVL DiTEST and AVL smoke meter were used to analyze the emissions including soot concentration (SC), pollution level (PL), filter smoke number (FSN), HC, NO_x and CO. The results obtained with HE-OBCU-EGR unit revealed 44.9%, 29.2%, 26.3%, 42.9% and 24.8% reduction in SC, PL, FSN, HC and NO_x emissions, whereas CO emissions were increased by 14.3% due to limited supply of oxygen from EGR. Results revealed that HE-OBCU-EGR unit may help to minimize the emissions of HC, SC, PL, FSN and NO_x but is not suitable to control CO emissions. To minimize the emissions of CO, this technology can be superposed with turbocharger or supercharger to enhance the availability of O₂ in the combustion chamber.

This experimental study investigates the impact of biodiesel derived from Jatropha oil and multiwalled carbon nanotubes (CNTs) on the performance and emissions of a diesel engine. The analysis involved five fuel conditions: pure diesel (D), diesel blended with 50% biodiesel (DB50), diesel blended with 80% biodiesel (DB80), diesel blended with 50% biodiesel and CNTs (DB50C), and diesel blended with 80% biodiesel and CNTs (DB80C). The results indicate that biodiesel blends, particularly those enhanced with CNTs, significantly improve fuel efficiency and engine performance. Blends with additives (DB50C and DB80C) exhibited higher brake power (BP) and lower brake‐specific fuel consumption (BSFC) across various engine speeds, indicating more effective energy conversion and better fuel economy. Moreover, emissions analysis revealed that biodiesel blends with CNTs significantly reduce harmful emissions. Emissions of carbon monoxide (CO), unburned hydrocarbons (UHCs), and nitrogen oxide (NO _x ) were consistently lower for DB50C and DB80C compared to D. The most notable reduction of 23.9% in NO _x emissions occurred at an engine speed of 2200, while CO and UHC emissions were reduced by 17.8% and 15.4%, respectively, at engine speeds of 1600 rpm. These findings suggest that the use of biodiesel with CNT additives not only increases combustion efficiency but also contributes to cleaner engine operation. This study emphasizes the potential of biodiesel, especially when combined with advanced nanoparticles, as a practical and environmentally friendly alternative to conventional diesel fuel.