A Computational Investigation of the Impact of Multiple Injection Strategies on Combustion Efficiency in Diesel???Natural Gas Dual-Fuel Low-Temperature Combustion Engines
| Autor: | Kalyan K. Srinivasan, Lorenzo Bartolucci, Vincenzo Mulone, Stefano Cordiner, Sundar Rajan Krishnan |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
020209 energy
Energy Engineering and Power Technology 02 engineering and technology Combustion computer.software_genre Methane Settore ING-IND/08 03 medical and health sciences chemistry.chemical_compound Diesel fuel Geochemistry and Petrology Natural gas Low temperature combustion 0202 electrical engineering electronic engineering information engineering Computer Aided Design Process engineering 030304 developmental biology 0303 health sciences Renewable Energy Sustainability and the Environment business.industry Mechanical Engineering Dual (category theory) Fuel Technology chemistry Environmental science Multiple injection business computer |
| Popis: | Dual-fuel diesel–methane low-temperature combustion (LTC) has been investigated by various research groups, showing high potential for emissions reduction (especially oxides of nitrogen oxide (NOx) and particulate matter (PM)) without adversely affecting fuel conversion efficiency in comparison with conventional diesel combustion. However, when operated at low load conditions, dual-fuel LTC typically exhibits poor combustion efficiencies. This behavior is mainly due to low bulk gas temperatures under lean conditions, resulting in unacceptably high carbon monoxide (CO) and unburned hydrocarbon (UHC) emissions. A feasible and rather innovative solution may be to split the pilot injection of liquid fuel into two injection pulses, with the second pilot injection supporting CO and UHC oxidation once combustion is initiated by the first one. In this study, diesel–methane dual-fuel LTC is investigated numerically in a single-cylinder heavy-duty engine operating at 5 bar brake mean effective pressure (BMEP) at 85% and 75% percentage of energy substitution (PES) by methane (taken as a natural gas (NG) surrogate). A multidimensional model is first validated in comparison with the experimental data obtained on the same single-cylinder engine for early single pilot diesel injection at 310 crank angle degrees (CAD) and 500 bar rail pressure. With the single pilot injection case as baseline, the effects of multiple pilot injections and different rail pressures on combustion and emissions are investigated, again showing good agreement with the experimental data. Apparent heat release rate and cylinder pressure histories as well as combustion efficiency trends are correctly captured by the numerical model. Results prove that higher rail pressures yield reductions of HC and CO by 90% and 75%, respectively, at the expense of NOx emissions, which increase by ∼30% from baseline still remaining at very low level (under 1 g/kWh). Furthermore, it is shown that postinjection during the expansion stroke does not support the stable development of the combustion front as the combustion process is confined close to the diesel spray core. |
| Databáze: | OpenAIRE |
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