Results in Engineering (Dec 2022)
Comparative evaluation of energy, performance, and emission characteristics in dual-fuel (CH4/Diesel) heavy-duty engine with RCCI combustion mode
Abstract
This paper tries to approach the combustion phase of RCCI by changing the input parameters of the engine, a dual-fuel methane/natural gas engine, to compare the performance of the engine under the influence of modifications in these factors. The effect of the most important factors on the combustion of the RCCI engine including the start time of single-stage injection, two-stage injection schedule, compression ratio, the amount of injection with high reactivity and the angle of injection, numerically (CONVERGE-CFD) and Laboratory test are analyzed. The results show that CO, NOX and HC pollutants increase with a delay in the onset of single-stage injection. The results for different two-stage injection schedules show that by doubling the injection time of the second stage, the temperature inside the chamber and the rate of heat released decrease. But the data for changing the compression ratio from 11.5 to 19 indicate that the temperature of the mixture at the end of the compression phase has increased by more than 700 K, which will be directly related to the ignition start time and the combustion duration. In addition, increasing the compression ratio reduces the production of CO and HC pollutants. For smaller amounts of high reactive fuels, the maximum temperature moves to areas farther away from the top dead center, increasing CO and HC emissions. Also, using a larger injection angle (from 55° to 70°) will reduce CO, NOX and HC pollutants because more diesel fuel is trapped in the gaps and squish regions.
