Advances in Diesel-LNG Internal Combustion Engines

Abstract

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...

A review on regulations, current status, effects and reduction strategies of emissions for marine diesel engines

“…The reduction in NOx emissions of biodiesel blend was also reported in two four-stroke six-cylinder supercharged marine auxiliary diesel engines [68][69][70]. However, the use of biodiesel in some multi-cylinder marine diesel engines yielded higher NOx emissions [61][62][63][64][65][66][67][68][69][70][71][72][73][74].…”

“…Properties of biodiesel, methanol, LNG, HFO, MDO and diesel[5,61,62,63,64].Biodiesel contains about 11% oxygen and has a trivial amount of sulphur and high centane number. Biodiesel can be applied to diesel engines in a simple way by blending with any proportion of diesel.…”

Decarbonization in Shipping Industry: A Review of Research, Technology Development, and Innovation Proposals

“…In addition, LNG originates from methane, which allows diversification of fossil fuel supplies. Under standard temperature and pressure conditions, LNG is a gas, hence LNG vaporizes, mixes and burns much better than diesel, thus achieving reduced emissions of regulated pollutants [99].…”

Future Power Train Solutions for Long-Haul Trucks

“…However, they point to a trade-off between NOX and hydrocarbon emissions from a dual fuel engine and state that the hydrocarbon and CO emissions may increase by more than 100 times. In another review, Boretti [167] concludes that the key properties of an LNG injector are its high pressure, fast actuation, high atomization, and flow rate, and that these lead to a better performance than diesel with reduced emissions of PM, NOx, and CO2.…”