Effect of advanced biofuels on WLTC emissions of a Euro 6 diesel vehicle with SCR under different climatic conditions

Abstract

Hydrotreated vegetable oil (HVO), a glycerol-derived biofuel (blended with diesel fuel at 20% v/v, Mo·bio®) and biodiesel produced through the esterification of residual free fatty acids from the palm oil industry (pure and blended with diesel fuel at 20% v/v), all of them considered as advanced biofuels as defined in the Directive EU/2018/2001, were tested in a Euro 6 diesel vehicle equipped with ammonia-SCR. Tests were carried out in a chassis dyno at warm (24°C) and cold (−7°C) ambient conditions following the Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). The efficiency of the SCR when changing the fuel was also analysed. Regarding vehicle performance, fuel properties were mainly relevant at warm conditions. Because of the lower EGR rate, NOx emissions upstream of the SCR were higher at cold temperature, mainly during the low and the extra-high speed phases of the WLTC. CO and THC emissions were only important at the beginning of the cycle and at −7°C. HVO presented advantages regarding these compounds, while the worse cloud point of biodiesel led to higher emissions. As expected, engine-out NOx emissions were very sensitive to the EGR rate, HVO showing a slightly better behaviour because of its high cetane number. The SCR efficiency was mainly affected by the exhaust gas temperature, although fuel-derived effects were also significant. In fact, a more appropriate NO2/NOx ratio at the catalyst inlet for HVO and a higher hydrocarbon concentration at the low-speed phase for B20 contributed to a lower tail-pipe NOx emissions at −7°C. The oxygen content of biodiesel-based fuels (B100 and B20) led to lower particle number with respect to diesel fuel. Despite its nil aromatic content, the higher EGR rate and the extremely superior autoignition trend of HVO led to higher particle number under high engine load and warm conditions.

Sustaining COVID-19 pandemic lockdown era air pollution impact through utilization of more renewable energy resources

“…The transport sectors accounts for one-fifth of global CO 2 emission which is equivalent to 60% of global oil consumption. Consequently, the use of ethanol, biodiesel and hydrogen will play a vital role in future ( Calle-Asensio et al., 2021 ). The EU has shown serious commitment to reduce the greenhouse emissions through the use of renewable energy fuels.…”

Special issue: THIESEL 2020 Conference on Thermo- and Fluid-Dynamic Processes in Direct Injection Engines

“…While in the special edition dedicated to the THIESEL 2018 conference, the papers reflected that improving Diesel and gasoline injection and combustion were still important issues to comply with emission regulations, the trend initiated already a few years back to bring new ways of controlling these has been consolidated in THIESEL 2020. Research has turned toward alternative fuels, such as biofuels (Calle-Asensio et al 1 ), ethanol (Giramondi et al 2 ), and natural gas (Winter et al 3 ). Studies presented in the THIESEL 2020 papers comprise the evaluation of advanced biofuels on the performance and regulated emissions of a Euro6 light-duty Diesel vehicle, 1 to injection strategies to enhance auto-ignition and combustion of ethanol fuel in CI heavy duty engines 2 and injection strategies optimization for dual gas-fuel.…”

“…Research has turned toward alternative fuels, such as biofuels (Calle-Asensio et al 1 ), ethanol (Giramondi et al 2 ), and natural gas (Winter et al 3 ). Studies presented in the THIESEL 2020 papers comprise the evaluation of advanced biofuels on the performance and regulated emissions of a Euro6 light-duty Diesel vehicle, 1 to injection strategies to enhance auto-ignition and combustion of ethanol fuel in CI heavy duty engines 2 and injection strategies optimization for dual gas-fuel. 3 The importance of reducing CO 2 emissions has led to studies about improving engine efficiency in a significant manner.…”

Impacts of the exhaust gas recirculation (EGR) combined with the regeneration mode in a compression ignition diesel engine operating at cold conditions

“…2 In order to fulfill these regulations, the internal combustion engine architecture is being continuously studied and improved by testing different strategies and systems that allow to reduce the impact of these pollutant emissions in the environment. 3,4 In this context, a widely known strategy used and improved during the last years is the exhaust gas recirculation (EGR) in its two configurations, the low pressure (LP) EGR, with a more complex architecture, and a more simple one, the high pressure (HP) EGR. 5,6 These strategies are presented as an effective solution to reduce the NO x emissions levels in different engine operating points, even working at cold conditions, when the pollutant emissions are largely critical due to the combustion degradation.…”