Utilization of Hydrotreated Vegetable Oil (HVO) in a Euro 6 Dual-Loop EGR Diesel Engine: Behavior as a Drop-In Fuel and Potentialities along Calibration Parameter Sweeps

Abstract

This study examines the effects on combustion, engine performance and exhaust pollutant emissions of a modern Euro 6, dual-loop EGR, compression ignition engine running on regular EN590-compliant diesel and hydrotreated vegetable oil (HVO). First, the potential of HVO as a “drop-in” fuel, i.e., without changes to the original, baseline diesel-oriented calibration, was highlighted and compared to regular diesel results. This showed how the use of HVO can reduce engine-out emissions of soot (by up to 67%), HC and CO (by up to 40%), while NOx levels remain relatively unchanged. Fuel consumption was also reduced, by about 3%, and slightly lower combustion noise levels were detected, too. HVO has a lower viscosity and a higher cetane number than diesel. Since these parameters have a significant impact on mixture formation and the subsequent combustion process, an engine pre-calibrated for regular diesel fuel could not fully exploit the potential of another sustainable fuel. Therefore, the effects of the most influential calibration parameters available on the tested engine platform, i.e., high-pressure and low-pressure EGR, fuel injection pressure, main injection timing, pilot quantity and dwell-time, were analyzed along single-parameter sweeps. The substantial reduction in engine-out soot, HC and CO levels brought about by HVO could give the possibility to implement additional measures to limit NOx emissions, combustion noise and/or fuel consumption compared to diesel. For example, higher proportion of LP EGR and/or smaller pilot quantity could be exploited with HVO, at low load, to reduce NOx emissions to a greater extent than diesel, without incurring penalties in terms of incomplete combustion species. Conversely, at higher load, delayed main injection timings and reduced rail pressure could reduce combustion noise without exceeding soot levels of the baseline diesel case.

Internal Combustion Engines and Carbon-Neutral Fuels: A Perspective on Emission Neutrality in the European Union

“…More specifically, E-fuel can be defined as all fuels produced by using renewable electricity from renewable sources (hydro, wind, or solar) with low carbon emissions, making them renewable fuels of non-biological origin used as feedstock or as an energy carrier with the purpose of mainstreaming renewable energy in transport vehicles [11]. On the other hand, synthetic fuels obtained either by pyrolysis or by catalytic hydrogenation of any triglyceride of biological origin are currently designated by different names, such as green diesel [12][13][14][15][16], renewable diesel [17][18][19][20][21][22], bio-hydrogenated diesel (BHD) [23][24][25], hydrogenated vegetable oils (HVOs) [26][27][28][29], alternative fuels [29][30][31][32][33], or advanced biofuels [34][35][36]. Furthermore, according to Figure 1, in the last decade, there has been an impressive increase in scientific publications that address the transformation of vegetable fats and oils into alkanes through different deoxygenation processes [36].…”

“…On the other hand, despite the doubts that have arisen regarding the immediate future of combustion thermal engines, with a horizon very close in 2035 [40], it cannot be forgotten that both spark ignition (SI) and compression ignition (CI) internal combustion engines (ICEs), mainly powered by fossil fuels [41][42][43], are actually the primary mobility sources nowadays [26], as indicated in Figure 3. Additionally, ICE diesel engines represent a significant proportion of these thermal engines, both in passenger cars and heavy-duty In summary, several "green fuels" have emerged as products of some pyrolysis or (hydro)cracking processes using different fats and oils as feedstocks [38].…”

Solid Particle Number (SPN) Portable Emission Measurement Systems (PEMS) for Heavy-Duty Applications

“…There are also some other boundary conditions that need further testing. For example, active regeneration events, different ambient temperatures, and different fuels such as hydrotreated vegetable oil (HVO) and CNG have received high attention over the past few years [47][48][49][50][51]. We are not aware of any other study assessing PEMS for heavy-duty vehicles.…”

The Impact of BioLPG’s on Carbon Footprint: A Context of European Countries

“…The method yields Propane [bioLPG] as a byproduct and HVO biodiesel (commonly known as "green" diesel as the primary product when carried out under carefully regulated temperature and pressure conditions [5]. From this angle, bioLPG appears to be a promising drop-in fuel-that is when replacing fossil LPG, it does not require any modifications to the infrastructure or equipment that will be used [6], and it also has fewer adverse environmental effects related to energy generation [7].…”