Effect of swirl ratio on NG/diesel dual-fuel combustion at low to high engine load conditions

Dual fuel combustion has garnered attention in recent years because of its potential for reducing emissions of oxides of nitrogen (NOx) and particulate matter (PM) while sustaining diesel-like fuel conversion efficiencies. However, most dual fuel combustion strategies suffer from higher engine-out hydrocarbon (HC) and carbon monoxide (CO) emissions, leading to poor combustion efficiencies, especially at low loads. The present work examined computationally the effect of in-cylinder swirl on diesel-ignited methane dual fuel combustion with a focus on devising strategies for improving part-load combustion efficiencies. For this purpose, diesel-methane dual fuel combustion was studied on a heavy-duty single cylinder research engine (SCRE) platform using CONVERGE computational fluid dynamics (CFD) software. A typical low load condition (IMEP = 5.1 bar) was selected at an engine speed of 1500 rpm and a relatively high methane percentage energy substitution (PES) of 80 percent (because experiments show poorer combustion efficiencies at high methane PES) at a nominal diesel injection timing of 2 degrees BTDC (358 CAD). The closed cycle simulation was first validated with experimental results (cylinder pressure and heat release histories as well as engine-out exhaust emissions) for neat diesel and diesel-methane dual fuel combustion, respectively. Subsequently, the influence of increasing swirl ratio from 0 to 1.5 on diesel-methane dual fuel combustion was characterized. Analysis of the computational results showed that peak cylinder pressure and heat release rate increased with increasing swirl ratio while the combustion duration (as determined by CA10-80) decreases from 25 CAD at a swirl ratio of 0.05 to nearly 15 CAD at a swirl ratio of 1.5. Indicated-specific hydrocarbon (ISHC) and indicated-specific carbon monoxide (ISCO) emissions decreased by about 60 percent and 50 percent, respectively, when swirl ratio was increased from 0.05 to 1.2; however, these reductions were accompanied by a 26 percent increase in indicated-specific NOx (ISNOx) emissions under these conditions. Therefore, the present study indicates that swirl optimization is a potentially viable strategy for reducing engine-out HC and CO emissions and for improving low-load combustion efficiencies in dual fuel engines, assuming additional NOx mitigation strategies are also employed simultaneously.

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High efficiency ethanol-diesel dual-fuel combustion: A comparison against conventional diesel combustion from low to full engine load

Fuel ◽

10.1016/j.fuel.2018.05.034 ◽

2018 ◽

Vol 230 ◽

pp. 440-451 ◽

Cited By ~ 32

Author(s):

Vinícius B. Pedrozo ◽

Ian May ◽

Wei Guan ◽

Hua Zhao

Keyword(s):

High Efficiency ◽

Fuel Combustion ◽

Dual Fuel ◽

Diesel Combustion ◽

Engine Load ◽

Dual Fuel Combustion

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Experimental Investigation of Dual-Fuel Combustion Characteristics inside a Gas Turbine Combustor

International Conference on Machine Learning, Electrical and Mechanical Engineering (ICMLEME'2014) Jan. 8-9, 2014 Dubai (UAE) ◽

10.15242/iie.e0114035 ◽

2014 ◽

Keyword(s):

Experimental Investigation ◽

Gas Turbine ◽

Fuel Combustion ◽

Combustion Characteristics ◽

Dual Fuel ◽

Gas Turbine Combustor ◽

Dual Fuel Combustion

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Study on dual fuel combustion in an optical research engine by infrared diagnostics varying methane quantity and engine speed

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2020.115623 ◽

2020 ◽

Vol 178 ◽

pp. 115623 ◽

Cited By ~ 1

Author(s):

Ezio Mancaruso ◽

Michele Todino ◽

Bianca Maria Vaglieco

Keyword(s):

Engine Speed ◽

Fuel Combustion ◽

Dual Fuel ◽

Dual Fuel Combustion ◽

Infrared Diagnostics

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Diesel CNG - The Potential of a Dual Fuel Combustion Concept for Lower CO2 and Emissions

10.4271/2015-26-0048 ◽

2015 ◽

Cited By ~ 6

Author(s):

Hans Juergen Manns ◽

Maximilian Brauer ◽

Holger Dyja ◽

Hein Beier ◽

Alexander Lasch

Keyword(s):

Fuel Combustion ◽

Dual Fuel ◽

Dual Fuel Combustion

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Mapping the combustion modes of a dual-fuel compression ignition engine

International Journal of Engine Research ◽

10.1177/14680874211018376 ◽

2021 ◽

pp. 146808742110183

Author(s):

Jonathan Martin ◽

André Boehman

Keyword(s):

Direct Injection ◽

Fuel Combustion ◽

Dual Fuel ◽

Compression Ignition ◽

Compression Ignition Engine ◽

Combustion Modes ◽

Si Engines ◽

Dual Fuel Combustion ◽

Soot Emissions ◽

Ci Engines

Compression-ignition (CI) engines can produce higher thermal efficiency (TE) and thus lower carbon dioxide (CO2) emissions than spark-ignition (SI) engines. Unfortunately, the overall fuel economy of CI engine vehicles is limited by their emissions of nitrogen oxides (NOx) and soot, which must be mitigated with costly, resource- and energy-intensive aftertreatment. NOx and soot could also be mitigated by adding premixed gasoline to complement the conventional, non-premixed direct injection (DI) of diesel fuel in CI engines. Several such “dual-fuel” combustion modes have been introduced in recent years, but these modes are usually studied individually at discrete conditions. This paper introduces a mapping system for dual-fuel CI modes that links together several previously studied modes across a continuous two-dimensional diagram. This system includes the conventional diesel combustion (CDC) and conventional dual-fuel (CDF) modes; the well-explored advanced combustion modes of HCCI, RCCI, PCCI, and PPCI; and a previously discovered but relatively unexplored combustion mode that is herein titled “Piston-split Dual-Fuel Combustion” or PDFC. Tests show that dual-fuel CI engines can simultaneously increase TE and lower NOx and/or soot emissions at high loads through the use of Partial HCCI (PHCCI). At low loads, PHCCI is not possible, but either PDFC or RCCI can be used to further improve NOx and/or soot emissions, albeit at slightly lower TE. These results lead to a “partial dual-fuel” multi-mode strategy of PHCCI at high loads and CDC at low loads, linked together by PDFC. Drive cycle simulations show that this strategy, when tuned to balance NOx and soot reductions, can reduce engine-out CO2 emissions by about 1% while reducing NOx and soot by about 20% each with respect to CDC. This increases emissions of unburnt hydrocarbons (UHC), still in a treatable range (2.0 g/kWh) but five times as high as CDC, requiring changes in aftertreatment strategy.

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