Thermofluids analysis of combustion, emissions, and energy in a biodiesel (C11H22O2) / natural gas heavy-duty engine with RCCI mode (Part II: Fuel injection time/ Fuel injection rate)

Abstract

Among the measures that improve the combustion process and reduce emissions in the design of dual-fuel engines is the use of the RCCI combustion strategy. This paper attempts to investigate the effects of biodiesel and diesel fuels, fuel injection time, and fuel injection rate in the RCCI combustion mode. In this study, using CONVERGE CFD commercial software and SAGE combustion model for the simulation. Accordingly, the geometry of a biodiesel (C11H22O2) / natural gas dual-fuel engine (Caterpillar 3401E) was exploited for experimental tests and numerical simulations. Results show that: The pressure inside the combustion chamber is especially greater from -12° to +10° crank angle for biodiesel, in fact, the maximum pressure for biodiesel fuel is approximately equal to 9.12 MPa and for diesel fuel is equal to 8.9 MPa. The mass of HC emissions for the two fuels is almost equal, but the mass of CO emissions for biodiesel is higher than diesel. By reducing the duration of fuel injection from 16° to 8° crank angle, the mass of soot is facing a decreasing trend, and this amount lowers from 0.065 to 0.00086 mg. Moreover, the indicated mean effective pressure (IMEP) and production work have increased from Case A (8 and 16 mg biodiesel in the first and second injection) to C (16 and 8 mg biodiesel in the first and second injection), and the knocking rate is reached from 3.4 to 6.6.

Keywords

• Biodiesel (C11H22O2)
• Fuel injection timing
• NOx
• CO
• HC
• Dual fuel