Prospective fuels for diesel low temperature combustion engine applications: A critical review

Thanks to its properties and production pathways, ethanol represents a valuable alternative to fossil fuels, with potential benefits in terms of CO2, NOx, and soot emission reduction. The resistance to autoignition of ethanol necessitates an ignition trigger in compression-ignition engines for heavy-duty applications, which in the current study is a diesel pilot injection. The simultaneous direct injection of pure ethanol as main fuel and diesel as pilot fuel through separate injectors is experimentally investigated in a heavy-duty single cylinder engine at a low and a high load point. The influence of the nozzle hole number and size of the diesel pilot injector on ethanol combustion and engine performance is evaluated based on an injection timing sweep using three diesel injector configurations. The tested configurations have the same geometric total nozzle area for one, two and four diesel sprays. The relative amount of ethanol injected is swept between 78 – 89% and 91 – 98% on an energy basis at low and high load, respectively. The results show that mixing-controlled combustion of ethanol is achieved with all tested diesel injector configurations and that the maximum combustion efficiency and variability levels are in line with conventional diesel combustion. The one-spray diesel injector is the most robust trigger for ethanol ignition, as it allows to limit combustion variability and to achieve higher combustion efficiencies compared to the other diesel injector configurations. However, the two- and four-spray diesel injectors lead to higher indicated efficiency levels. The observed difference in the ethanol ignition dynamics is evaluated and compared to conventional diesel combustion. The study broadens the knowledge on ethanol mixing-controlled combustion in heavy-duty engines at various operating conditions, providing the insight necessary for the optimization of the ethanol-diesel dual-injection system.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of the diesel pilot injector configuration on ethanol combustion and performance of a heavy-duty direct injection engine

Giramondi

Jäger

Norling

et al. 2021

“…In addition, low combustion temperature can also cause incomplete conversion of fuel to CO2, thereby reducing efficiency and increasing CO and HC emissions. To solve these shortcomings, a large number of combustion control strategies have been proposed and examined both experimentally and numerically that can be organized into four main categories including variable compression ratio [16][17], variable intake conditions [18][19][20], regulated Exhaust Gas Recirculation (EGR) [21][22][23][24] and adjustable fuel blends [25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

“…To solve these shortcomings, a large number of combustion control strategies have been proposed and examined both experimentally and numerically that can be organized into four main categories including variable compression ratio, 16,17 variable intake conditions, 18–20 regulated Exhaust Gas Recirculation (EGR), 21–24 and adjustable fuel blends. 25–27…”

Section: Introductionmentioning

confidence: 99%

A numerical study of the effects of oxy-fuel combustion under homogeneous charge compression ignition regime

Mobasheri

Aïtouche

Peng

et al. 2021

The European Union (EU) has recently adopted new directives to reduce the level of pollutant emissions from non-road mobile machinery engines. The main scope of project RIVER for which this study is relating is to develop possible solutions to achieve nitrogen-free combustion and zero-carbon emissions in diesel engines. RIVER aims to apply oxy-fuel combustion with Carbon Capture and Storage (CCS) technology to eliminate NOx emissions and to capture and store carbon emissions. As part of this project, a computational fluid dynamic (CFD) analysis has been performed to investigate the effects of oxy-fuel combustion on combustion characteristics and engine operating conditions in a diesel engine under Homogenous Charge Compression Ignition (HCCI) mode. A reduced chemical n-heptane-n-butanol-PAH mechanism which consists of 76 species and 349 reactions has been applied for oxy-fuel HCCI combustion modeling. Different diluent strategies based on the volume fraction of oxygen and a diluent gas has been considered over a wide range of air-fuel equivalence ratios. Variation in the diluent ratio has been achieved by adding different percentages of carbon dioxide for a range from 77 to 83 vol.% in the intake charge. Results show that indicated thermal efficiency (ITE) has reduced from 32.7% to 20.9% as the CO2 concentration has increased from 77% to 83% at low engine loads while it doesn’t bring any remarkable change at high engine loads. It has also found that this technology has brought CO and PM emissions to a very ultra-low level (near zero) while NOx emissions have been completely eliminated.

“…These components can be additives but also other fuels, such as environmentally friendly biodiesel, at low but lubricity-imparting levels. [12][13][14][15][16][17] In literature, lubricity studies related to ULSD and alternative fuels have been mostly conducted by employing ASTM D-6079 (ISO 12156; Standard Test Method for Evaluating Lubricity of Diesel Fuels by the High-Frequency Reciprocating Rig (HFRR)). The method specifies and restricts the load, speed, motion, and contact metals for practical purposes and reports the mean wear scar diameter (MWSD) as an average of the two wear scar diameter (WSD) taken at two different axes, as a test measure.…”

Section: Introductionmentioning

confidence: 99%

Lubricity assessment of ultra-low sulfur diesel fuel (ULSD), biodiesel, and their blends, in conjunction with pure hydrocarbons and biodiesel based compounds

Tat

Çelik

et al. 2021

This research aimed to investigate the lubricity and wear properties of ultra-low sulfur diesel fuel (ULSD) blended with biodiesel and doped with biodiesel-based organic compounds. In this work, neat n-dodecane served as a surrogate for ultra-low sulfur diesel fuel (ULSD), Fischer Tropsch, and renewable diesel fuels. Additionally, some pure hydrocarbons were also investigated for unsaturation and carbon chain length. Tribological characterization was conducted on quenched and tempered AISI 4140 steel, substituting diesel fuel pump material, and using the ball-on-disc technique. The wear rates of biodiesel samples were about 2–4 times less than the vegetable oils. Esterification improves the lubricity of vegetable oils. The wear rate of biodiesel is about 5–7 times greater than that of fossil base commercial Eurodiesel fuel. Using biodiesel as an additive had a significant effect on the lubricity of pure n-dodecane, adding 2 wt% biodiesel resulted in 5–7 times wear rate reduction that equivalent to the lubricity level of commercial Eurodiesel fuel. Wear rates of pure hydrocarbons showed that wear is reduced with increasing chain length and unsaturation.