Mechanism of hydrocarbon reduction using multiple injection in a natural gas fuelled/micro-pilot diesel ignition engine

Abstract

Research has shown that a large amount of natural gas (NG) is unburned at light loads in an NG fuelled/micro-pilot diesel compression ignition engine. A mechanism of unburned hydrocarbon (HC) reduction using multiple injections of micro-pilot diesel has been proposed in this paper. Multidimensional computations were carried out for a dual-fuel engine based on a modified CAT3401 engine configuration. The computations show that a split injection with a small percentage (e.g. 30 per cent of diesel in the second injection pulse) can significantly reduce HC, CO and NOx emissions. Based on parametric studies to optimize the timing of both of the injection pulses, HC emissions could be reduced by 90 per cent, with a reduction in CO emissions of 50 per cent and NOx emissions of 70 per cent in comparison to a single-injection pulse-base case configuration.

A numerical investigation on combustion and emission characteristics of a dual fuel engine at part load condition

“…Two step reactions are added to code from research work published by Micklow and Gong [9]. These two reactions include: …”

“…(13) and (14). Also six equilibrium reactions are considered in combustion process as follows [9,23,24]: Since the contribution of NO formation is greater than Nitrogen Dioxide (NO 2 ), so NO formation mechanism is studied mainly [28]. Extended Zeldovich's mechanism has been utilized for NO formation [23,24].…”

“…Micklow and Gong studied performance and emission characteristics of a dual fuel engine at part load conditions using KIVA-3V code. Results showed that 40% of methane remained unburned near the cylinder wall [9]. Kusaka et al used KIVA-3V code coupled with Chemkin-II for modeling of a dual fuel engine at part load conditions.…”

Reducing Diesel Engine Emission Using Reactivity Controlled Approach

“…Moreover, the simulation of the combustion process inside the engine is a very complex process because it is a result of the interaction between many phenomena that occur inside the combustion chamber, such as fuel injection, vaporization, mixing, turbulent motion, ignition, and flame prorogation [6]. The combustion process with details kinetics technique obtained by CFD is essential to better understand the phenomena which occur inside the engine, resulting in the possiblity to optimize the engine parameters for drawing the maximum benefit from the dual fuel engine [13]. Kim et al [14] have investigated the effect of the gasoline ratio, the injection pressure and the intake temperature on the engine performance and emissions.…”

“…Moreover, under fixed intake air temperature conditions, increased gasoline ration in the fuel raised HC and CO emission. Lopez et al [13] investigated the effect of different gasoline and diesel blends ratio on ignition delay and flame structure for diesel engine. The results confirmed that the soot formation is affected by the flame lift-off length which is related to the fuel reactivity.…”