Investigation of diesel engine characteristics under pilot injection mode using diesel-DTBP blends

Numerous studies have blended cetane number improver (CNI) in diesel engine fuels for compensating the drop in cetane number (CN) when alcohol/biodiesel fuel is blended with diesel fuel. However, the studies that focused on using CNI with neat diesel fuel (D100) are very limited. Moreover, the majority of the earlier studies that used CNI are based on conventional single injection (SI) only. The presented work experimentally investigates the influence of adding CNI in D100 on diesel engine combustion under pilot injection (PI) mode which can be of significant novelty. The importance of CNI is more significant under PI mode because it leads to more complete combustion of pilot fuel before the main injection starts. Di-Tert-Butyl Peroxide (DTBP) was used as CNI and added into D100 in concentration of 1% by volume. The SI with D100 was considered as a reference condition and the test engine was operated at fixed load and speed of 90% and 1600 rpm respectively. Preliminary experiments conducted with D100 showed that implementing PI offers a considerable reduction in nitrogen oxides (NO_x) emissions compared to SI while increasing smoke emissions. When DTBP was added in D100, it caused more complete and faster combustion of pilot fuel before commencement of main injection. The obtained results revealed that diesel/DTBP blend under PI mode with 10% pilot quantity and - 24° after top dead center (ATDC) pilot injection timing offered 20.8% and 64.29% reduction in NO_x and hydrocarbon (HC) emissions respectively compared to the reference conditions while increasing smoke emissions by 71.42%.