Investigation of Diesel and CNG Combustion in a Dual Fuel Regime and as an Enabler to Achieve RCCI Combustion

Dahodwala, Mufaddel; Joshi, Satyum; Koehler, Erik; Franke, Michael

doi:10.4271/2014-01-1308

Cited by 44 publications

(28 citation statements)

References 7 publications

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“…At low load operations as φ a equals to 3.25, the power is increased by 0.17 kW (3.7%) at substitution rates of 20% and reduced by 0.26 kW (5.7%) at substitution rates of 40% compared to that of pure diesel operation. As shown in Figure 4, the combustion phasing is retarded and the peak in-cylinder pressure decreases with the increase of substitution rate, especially at 80% substitution rate which was observed previously [24,25]. It can be explained that too lean a mixture and a smaller pilot diesel injection slow down the burn rate and most of the NG-air mixture is burned in the post-combustion period during the expansion stroke as the instantaneous heat release rate (HRR) trace expresses the same phenomenon with increasing substitution rate [26].…”

Section: Power Outputsupporting

confidence: 73%

Experimental Study on the Effects of Air Supply Control on Combustion and Emissions Performance at Medium and Low Load for a Dual-Fuel Diesel Engine

et al. 2018

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Lowering the amount of excess air is believed to increase the density of the air-fuel mixture and help improve the combustion rate for compression ignition engines. This paper proposes an approach of adding a throttle body at the intake pipe to control the excess air ratio with reduction of air supply to achieve a better balance between the power, emissions and fuel efficiency at medium and low load of a natural gas dual-fuel diesel engine converted from a conventional diesel engine. Various experiments in both pure diesel and dual-fuel mode under intermediate engine speed are performed with the proposed critical method of excess air ratio control. The experimental results reveal that better excess air ratio is very beneficial for the power output and brake specific energy consumption in dual-fuel combustion under medium and low load conditions. Moreover, the substitution rate can reach as high as 40% under low load conditions with throttle control.

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Section: Power Outputsupporting

confidence: 73%

Experimental Study on the Effects of Air Supply Control on Combustion and Emissions Performance at Medium and Low Load for a Dual-Fuel Diesel Engine

et al. 2018

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“…Then, they computationally studied DI-NG (direct injection of natural gas) in RCCI engine and found out that the DI-NG concept creates enhanced stratification of the NG fuel portion and avoids excessive premixing, which tempers the RoPR, thus enables higher load operation [20]. Dahodwala et al [21] experimentally investigated Diesel/CNG combustion to achieve RCCI combustion. It was demonstrated that RCCI combustion could be achieved at low loads, which enabled even higher CNG substitution and lower emissions.…”

Section: Introductionmentioning

confidence: 98%

Effects of diesel injection strategy on natural gas/diesel reactivity controlled compression ignition combustion

Paykani

Kakaee

Rahnama

et al. 2015

Energy

135

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“…Similar CO emissions trends were also reported by other researchers [15,19,20]. Numerous experimental studies reported the effect of diesel fuel quantity and injection timing on CO emissions from NG-diesel dual fuel engines [26,[34][35][36]. For example, Liu et al [26] experimentally studied the effect of pilot fuel quantity on the emission characteristics of a NG-diesel dual fuel engine.…”

Section: Co Emission From Ng-diesel Dual Fuel Enginesupporting

confidence: 74%

A Numerical Investigation of Natural Gas-Diesel Dual Fuel Engine Combustion and Emissions Using CFD Model

Yu¹

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Natural gas (NG)-diesel dual fuel engines have been highlighted for their fuel flexibility and high thermal efficiency comparable to diesel engines. However, the addition of NG to compression ignition diesel engines was reported to elongate ignition delay and to increase the emissions of carbon monoxide (CO), unburned methane (CH4), and nitrogen dioxide (NO2). Past research on dual fuel engines has focused on the experimental research on the engine performance, combustion process, and exhaust emissions. The research on detailed mechanism dominating the impact of CH4 on formation of CO and NO2 in cylinder, and the mechanism for CH4 to survive the combustion process and slip through the cylinder is limited. The examinations of these mechanisms require the simulation of dual fuel engine combustion using a CFD model coupled with chemical kinetic mechanism. This research numerically investigates the combustion process and exhaust emissions from two NG-diesel dual fuel engines using a CFD model coupled with a reduced primary reference fuel (PRF) chemistry. The CFD model used is Converge-SAGE model with a maximum of 300000 grid points. The fuel chemistry used is a reduced PRF mechanism with 45 species and 142 reactions including a reduced NOx mechanism with 4 species and 12 reactions. The CFD model with reduced PRF chemistry has been validated against experimental data measured in a single-cylinder compression-ignition engine over a wide range of CH4 substitution ratio. A post-processing tool has been developed to calculate, analyze, and visualize the instantaneous rate of production (ROP) of key species in each cell with the known temperature, pressure, and species concentration exported by CFD code. The simulation results are further post-processed to numerically investigate the combustion process and the formation mechanism of CO, and NO2 in a dual fuel engine. The mechanism for CH4 to survive the main combustion process and post-combustion oxidation process is numerically examined. The research on NO2 formation identified NO+HO2→NO2+OH as the key reaction dominating the increased formation of NO2 in dual fuel engines. The HO2 necessary for the formation of NO2 emitted by the engine is produced through the post-oxidation of CH4 that survived the main combustion process. The CO emitted from the NG-diesel dual fuel engine is formed through the oxidation of CH4 during the late

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Investigation of Diesel and CNG Combustion in a Dual Fuel Regime and as an Enabler to Achieve RCCI Combustion

Cited by 44 publications

References 7 publications

Experimental Study on the Effects of Air Supply Control on Combustion and Emissions Performance at Medium and Low Load for a Dual-Fuel Diesel Engine

Experimental Study on the Effects of Air Supply Control on Combustion and Emissions Performance at Medium and Low Load for a Dual-Fuel Diesel Engine

Effects of diesel injection strategy on natural gas/diesel reactivity controlled compression ignition combustion

A Numerical Investigation of Natural Gas-Diesel Dual Fuel Engine Combustion and Emissions Using CFD Model

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