Effect of hydraulic flow rate, injection timing, and exhaust gas recirculation on particulate and gaseous emissions in a light-duty diesel engine

Abstract

Nozzle hydraulic flow rate is a critical parameter that affects the combustion process and plays a vital role in the production of emissions from a diesel engine. In this study, injection characteristics, such as normalized injection rate and spray tip penetration, were analyzed for different hydraulic flow rate injectors with the help of spray experiments. To further investigate the effects of hydraulic flow rate on engine-out particulate and gaseous emissions, engine experiments were performed for different values of hydraulic flow rate in multiple injectors. Various operating conditions and loading configurations were examined, and the effects of varying start of injection and exhaust gas recirculation rates for different hydraulic flow rates were analyzed. A separate Pegasor Particle Sensor (PPS-M) sensor was used to measure and collect data on the particle number, and an analysis was conducted to investigate the relation of particle number with hydraulic flow rate, injection timing, and exhaust gas recirculation rate. Results of the spray experiment exhibited a decreasing injection duration and increasing spray tip penetration with increasing hydraulic flow rate. Effect of hydraulic flow rate on combustion and emission characteristics were analyzed from engine experiment results. Least ignition delay was achieved using a smaller hole diameter, retarded injection timing, and lowest EGR%. Higher hydraulic flow rate with retarded injection timing and higher EGR% helped in reduction of NOx emissions and brake-specific fuel consumption, but particulate emissions were increased. Best particulate matter–NOx trade-off was achieved with lowest hydraulic flow rate.

Review of morphological and chemical characteristics of particulates from compression ignition engines

“…Lowering the EGR rate and advancing the SoI timing reduce PM emissions (Figure 4). 99 However, their effects on PM reduction are reduced by decreasing the hydraulic flow rate (HFR; the volume of fuel flow per unit time) due to improved fuel-air mixture strength. Lower compression ratio (CR) engines emit higher PM than higher CR engines (Figure 5).…”

Evaluation of different injectors-swirl configurations on combustion and emissions characteristics in a medium-duty compression ignition diesel engine

“…Hydraulic nozzle flowrate has been broadly studied in diesel engines, finding that a reduction in flowrate can have beneficial effects on soot formation and NOx. 25,26 Rollbusch 27 found that a lower hydraulic flowrate can promote less soot by means of a higher mean relative air-to-fuel ratio at medium loads, while the same effect was not present at full loads. Reducing hole diameter in the nozzle can affect the local mixing rate, which translates into better gas entrainment that can be associated with lower fuel consumption.…”