Numerical analysis of the combustion process of oxymethylene ethers as low-carbon fuels for compression ignition engines

Abstract

Mitigation of the carbon footprint of internal combustion engines is mandatory to ensure a future for this technology. Within this scope, e-fuels are considered a potential solution to replace conventional fossil fuels. However, in some cases, their physical and chemical properties are so different that its application in conventional engines is complex. For this reason, this work focuses on the study of oxymethylene ethers (OMEX) as a potential low-carbon fuel alternative. The aim is to improve the understanding of the combustion process of these e-fuels when they replace fossil Diesel in internal combustion engines under equivalent operating conditions. To achieve this objective, a computational fluid dynamics model of an optical compression ignition engine has been developed. The operating conditions chosen are representative of a medium load point of the engine, which coincide with experimental work previously done on this platform. n-Heptane was used as surrogate of fossil Diesel while OMEX was simulated as a simpler mixture of oxymethylene ether molecules. Results show remarkable differences between Diesel and OMEX. This fuel provides lower equivalence ratio fields. Thus, oxidation reactions are promoted in wider areas within the combustion chamber, leading to a faster combustion process. Besides, the soot formation is also drastically decreased in comparison to the other fuel. These results have been corroborated with experimental information.

LES and RANS Spray Combustion Analysis of OME3-5 and n-Dodecane

“…The entire combustion process was shown not to exceed equivalence ratios greater than two for OME, which is, of course, in stark contrast to the combustion of n-paraffinic fuel like n-dodecane. These observations were confirmed for a single-cylinder optically accessible diesel engine in [18] using the same RANS setup and injection strategy and also recently by García-Oliver et al [19] utilizing a different simulation setup and injection strategy but the same OME fuel. However, the simulations could not reproduce the strong OH* chemiluminescence signal in the spray center axis and the peak intensity near the flame lift-off length in either the constantpressure vessel or the single-cylinder engine.…”

A numerical analysis of hydrotreated vegetable oil and dimethoxymethane (OME1) blends combustion and pollutant formation through the development of a reduced reaction mechanism

“…In other words, the amount of CO 2 released during their combustion is the same as the one utilized while producing them. 14 Among e-fuels, polyoxymethylene dimethyl ethers often denoted as oxymethylene ethers (OME x ) are getting serious attention of researchers in the last decade. OME x are hydrocarbons having a chemical formula of CH 3 O-(CH 2 O) x -CH 3 where x varies from 1 to 6.…”

Analysis of Particle Number Emissions in a Retrofitted Heavy Duty-Spark Ignition Engine Powered by LPG

“…In this context, retrofit old engines to operate on low-carbon fuels as a medium-term solution during the energy transition [13]. This approach first reduces the environmental impact associated with the production of new engines [14] and, secondly, lowers CO2 emissions, which are directly related to the carbon content of the fuel [15].…”