A detail simulation of reactivity controlled compression ignition combustion strategy in a heavy-duty diesel engine run on natural gas/diesel fuel

Abstract

The aim of this study is to investigate in details the effects of a number of combustion parameters to optimize the reactivity controlled compression ignition operation running on natural gas and diesel fuel. In the present work, a singlecylinder heavy-duty diesel engine with a specially modified bathtub piston bowl profile for reactivity controlled compression ignition operation is studied and simulated through commercial software. A broad load range from 5.6 to 13.5 bar indicated mean effective pressure at a constant engine speed of 1300 r/min, fixed amount of diesel fuel mass, and with no exhaust gas recirculation is considered. The results from the developed model confirm that the model can accurately simulate the reactivity controlled compression ignition combustion. Also, by focusing on the time of formation of certain important radicals in combustion, the start of combustion and the time of natural gas dissociation are accurately predicted. Furthermore, the influence of some parameters such as different diesel fuel injection strategies, intake temperature, and intake pressure on the reactivity controlled compression ignition combustion is evaluated and the limitation of the engine operation at low temperature combustion is investigated.

Multi-input–multi-output optimization of reactivity-controlled compression-ignition combustion in a heavy-duty diesel engine running on natural gas/diesel fuel

“…26 The sub-models used in the present simulation are the turbulent dispersion by Gosman and Ioannides, 27 the coalescence/collision (wall jet) by Naber and Reitz, 28 the evaporation by Dukowicz, 29 the break-up (standard wave) by Liu and Reitz, 30 and the diesel nozzle flow by Kunsberg-Sarre et al 31 A 60° sector (assuming six injection holes, each hole located in one-sixth segment of a cylindrical grid) three-dimensional (3D) computational grid which is used for the present simulation of RCCI combustion is depicted in Figure 2. 15 The developed simulation model is verified by the experimental data of Walker et al 14 and is explained in detail by the present authors in Ebrahimi et al 15…”

“…In order to implement the DOEs concept—factorial method—in the proposed RCCI combustion simulation, the effects of several important input factors on the engine performance should be studied. Based on the experimental and simulation works, 14,15 among the effective input factors, some factors such as engine speed, equivalence ratio, amount of diesel fuel mass per cycle, mass fuel ratio of methane per diesel, and amount of methane mass per cycle are considered to be constant. Also, based on the works by Walker et al 14 and Ebrahimi et al, 15 EGR percentage is set to be zero, diesel fuel is injected in the combustion chamber in a single stage, and the bathtub profile is selected for the piston bowl profile.…”

“…Based on the experimental and simulation works, 14,15 among the effective input factors, some factors such as engine speed, equivalence ratio, amount of diesel fuel mass per cycle, mass fuel ratio of methane per diesel, and amount of methane mass per cycle are considered to be constant. Also, based on the works by Walker et al 14 and Ebrahimi et al, 15 EGR percentage is set to be zero, diesel fuel is injected in the combustion chamber in a single stage, and the bathtub profile is selected for the piston bowl profile. Therefore, for a further comparison of the results with those of the experimental work and the present authors’ earlier simulation work, 14,15 the current optimization study only focuses on the effect of three control factors on the engine performance as response variables at 9.4 bar IMEP g (mid-load range).…”

“…7–11 Natural gas (NG) as the low-reactivity fuel has become more demanding and has been the subject of many studies. 12–15 NG is a mixture of methane, ethane, propane, butane, pentane, and other elements such as sulfur, carbon dioxide, and nitrogen at different proportions. However, methane is the dominant element in NG; generally, methane is accepted as the representative for natural gas.…”

Simulation of Dual Fuel Combustion of Direct Injection Engine with Variable Natural Gas Premixed Ratio

“…This phase with lower rate is due to the premixed combustion of the diesel fuel and is increased by increasing the ratio of injection of the high-reactive diesel fuel as can be seen in Figure 6. The second phase of the combustion is considered as the high temperature heat release (HTHR) having higher rate and is influenced by the combustion of the premixed natural gas [16]. Based on the results, increasing the premixed ratio of natural gas to 90% reduces LTHR and HTHR significantly which is an indicator of the occurrence of partial/misfire burning and flame quenching in the cylinder.…”