Thermofluids analysis of combustion, emissions, and energy in a biodiesel (C11H22O2) / natural gas heavy-duty engine with RCCI mode (Part I: Single/ two -stage injection)

Abstract

• The effects of fuel injection strategy for using the concept of RCCI combustion in a heavy-duty biodiesel engine have been investigated. • For the first time in a heavy-duty biodiesel engine, biodiesel fuel (C 11 H 22 O 2 ) as a new fuel has been used in this level. • Changing the high reactivity fuel injection time from -40° to -60°, the rate of heat released decreases but output power increases. • The mass of HC and CO pollutants has drastically decreased with the onset of injection earlier. One of the novel methodologies used to increase energy efficiency and reduction of environmental pollutants in internal combustion engines is the idea of low-temperature combustion (LTC) especially reactivity controlled compression ignition (RCCI). Given that the ultimate goal of RCCI combustion is combustion controllability through in-cylinder reactivity stratification by using two different fuels, there are many modifiable factors, which can be improved or adjusted. The aim of this research is to use the concept of RCCI combustion in a biodiesel (C 11 H 22 O 2 ) / natural gas heavy-duty engine and the performance and amount of pollutants of engine output is evaluated and compared by modifying the input parameters (different fuel injection strategy). Accordingly, numerical simulations have been carried out to study combustion in the geometry of the Caterpillar 3401E engine with CONVERGE computational fluid dynamic software and the SAGE combustion model. Results show that: By changing the biodiesel injection time (from -40° to -60°), although, the rate of heat released decreases, output work and Indicated mean effective pressure (IMEP) increase. By increasing the lag of time between the first and second injections (in Cases 1–3), the IMEP will increase from 6.9 to 8.2 bar and the work from 1686 to 1997 J. In Cases (7–9), the mass of HC and CO pollutants has drastically decreased with the onset of injection earlier, whereas the mass of NOx pollutants has increased.