Experimental Study on the Load Characteristics of Diesel-LNG Hybrid Diesel Engines

Wang, Shu Xin; Zhang, Jin; Jiang, S. Y.

doi:10.4028/www.scientific.net/amr.356-360.1375

Cited by 3 publications

(2 citation statements)

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“…Because of the cryogenic temperatures, LNG is more practical on large HDT continuously in movement than small passenger cars mostly parked. Diesel-LNG engines are becoming popular for ships and heavy-duty truck propulsion [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Advances in Diesel-LNG Internal Combustion Engines

Boretti

2020

Applied Sciences

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Diesel-LNG internal combustion engines (ICEs) are the most promising light and heavy-duty truck (HDT) powering solution for a transition towards a mixed electric-hydrogen renewable energy economy. The diesel-liquid CH 4 ICEs have indeed many commonalities with diesel-liquid H 2 ICEs, in the infrastructure, on-board fuel storage, and injection technology, despite the fact H 2 needs a much lower temperature. The paper outlines the advantages of dual fuel (2F) diesel-LNG ICEs developed adopting two high-pressure (HP) injectors per cylinder, one for the diesel and one for the LNG, plus super-turbocharging. The diesel-LNG ICEs provide high fuel energy conversion efficiencies, and reduced CO 2 , PM, and NOx emissions. Super-turbocharging permits the shaping of the torque curve while improving acceleration transients. Diesel-LNG ICEs may also clean up the air of background pollution in many polluted areas in the world. Computational results prove the steady-state advantages of the proposed novel design. While the baseline diesel model is a validated model, the 2F LNG model is not. The perfect alignment of the diesel and diesel-LNG ICE performances proven by Westport makes however the proposed results trustworthy. the lean-burn operation, with combustion occurring with excess air [23]. The reduction of both PM and NOx is achieved by after-treatment. As the after-treatment is imperfect, the diesel combustion strategies are dictated by the best trade-off between PM and NOx emissions.The use of a fuel with reduced carbon content, that is also gas in normal conditions, such as the NG, has major advantages in both CO 2 and engine-out PM emissions. Even if injected liquid, the NG rapidly vaporizes and quickly mixes with the air. The PM emissions are usually negligible. Not having the constraint of the best PM-NOx trade-off to design the injection profile, the injection profile can be shaped to achieve reduced NOx production. Thus, NG indirectly also permits to reduce the NOx engine-out emissions. NG (CH 4 ) has a smaller carbon-to-hydrogen ratio vs. the diesel (C 13.5 H 23.6 ) also featuring a higher lower heating value. Less CO 2 is emitted to produce the same output of the diesel with the same η. As NG is also gas in normal conditions, this practically reduces to zero the PM emissions. In the dual-fuel (2F) operation, the only PM originates from the pilot diesel.As NG is a low cetane but a high octane number fuel, it is difficult to use alone in a CI ICE The issue is solved by using the 2F diesel-NG design with the diesel-injection-ignition [24,25]. A small amount of the DI diesel fuel ignites mixed with air within the cylinder. The NG that is injected prior, or after the diesel, then burns premixed, i.e. diffusion. The first phase of combustion translates into a rapid pressure build-up. The rate of combustion of the second phase is determined by the injection rate of the NG.One issue with fuels that are gases under normal conditions is the specific volume, as the density of the gas under normal conditions is much lower than...

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Section: Introductionmentioning

confidence: 99%

Advances in Diesel-LNG Internal Combustion Engines

Boretti

2020

Applied Sciences

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“…This could drastically improve CO 2 emissions, while also improve the use of natural resources. By replacing a conventional diesel engine with a higher efficiency, diesel-liquefied natural gas (LNG) engine, there is the advantage of the C/H ratio of the fuel, the advantage of reduced depletion of natural resources, the advantage of reduced emissions of pollutants, starting from PM, the diversification of fuel sources, the security of the fuel sources, see references from [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], just to mention a few. The starting point for this work is given in [4], which describes the advantages of diesel-LNG engines.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of High-Pressure Direct Injection Dual-Fuel Diesel-Liquefied Natural Gas (LNG) Engines

Boretti¹

2020

Processes

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Dual fuel engines using diesel and fuels that are gaseous at normal conditions are receiving increasing attention. They permit to achieve the same (or better) than diesel power density and efficiency, steady-state, and substantially similar transient performances. They also permit to deliver better than diesel engine-out emissions for CO2, as well as particulate matter, unburned hydrocarbons, and nitrous oxides. The adoption of injection in the liquid phase permits to further improve the power density as well as the fuel conversion efficiency. Here, a model is developed to study a high-pressure, 1600 bar, liquid phase injector for liquefied natural gas (LNG) in a high compression ratio, high boost engine. The engine features two direct injectors per cylinder, one for the diesel and one for the LNG. The engine also uses mechanically assisted turbocharging (super-turbocharging) to improve the steady-state and transient performances of the engine, decoupling the power supply at the turbine from the power demand at the compressor. Results of steady-state simulations show the ability of the engine to deliver top fuel conversion efficiency, above 48%, and high efficiencies, above 40% over the most part of the engine load and speed range. The novelty of this work is the opportunity to use very high pressure (1600 bar) LNG injection in a dual fuel diesel-LNG engine. It is shown that this high pressure permits to increase the flow rate per unit area; thus, permitting smaller and lighter injectors, of faster actuation, for enhanced injector-shaping capabilities. Without fully exploring the many opportunities to shape the heat release rate curve, simulations suggest two-point improvements in fuel conversion efficiency by increasing the injection pressure.

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