The early and late injection timing is known to have significant effects on the emission, performance and combustion characteristics of an internal combustion engine (ICE) fuelled by hydrogen enriched compressed natural gas employing exhaust gas recirculation (CNG-H2-EGR). However, different injection timings has different effects on the emission characteristics of the ICE which are difficult to be distinguished (increase or decrease the rate of emission of NO, CO and UHC). Therefore, the impact of the early and late injection timing on the emission characteristics of the ICE engine fuelled by hydrogen enriched compressed natural gas with the usage of exhaust gas recirculation (DI-CNG-H2-EGR) is not perfectly understood. The primary objective of this research is to experimentally study the effects of early and late injection timing on the emission characteristics of internal combustion engine fuelled by CNG-H2 employing EGR. The experiment was conducted on part-throttle, constant engine speed of 2000rpm, with different fractions of hydrogen gas of 0%, 28% and 46% and EGR percentage of 0%, 15%, 30% and 45%. The result showed that for a given percentage of hydrogen gas, the late injection timing gives more drastical reduction in the emission characteristics of DI-CNG-H2-EGR compared to early injection timing. This might be due to mixture stratification occasioned by late injection timing. Furthermore, the result also suggests that the percentage of EGR that guaranteed the best emission control for the DI-CNG-H2-EGR lies between 15% and 30% (i.e. 15% for BSNO, 30% for BSUHC and 30% for BSCO). From the foregoing analysis, it can technically be concluded that the late injection timing is more effective strategy to achieve low emission characteristics in DI-CNG-H2-EGR engine as compared to early injection timing.
Volume 11 | Issue 1
Pages: 31 - 41