The energy impact of adaptive cruise control in real-world highway multiple-car-following scenarios

Abstract Background Surging acceptance of adaptive cruise control (ACC) across the globe is further escalating concerns over its energy impact. Two questions have directed much of this project: how to distinguish ACC driving behaviour from that of the human driver and how to identify the ACC energy impact. As opposed to simulations or test-track experiments as described in previous studies, this work is unique because it was performed in real-world car-following scenarios with a variety of vehicle specifications, propulsion systems, drivers, and road and traffic conditions. Methods Tractive energy consumption serves as the energy impact indicator, ruling out the effect of the propulsion system. To further isolate the driving behaviour as the only possible contributor to tractive energy differences, two techniques are offered to normalize heterogeneous vehicle specifications and road and traffic conditions. Finally, ACC driving behaviour is compared with that of the human driver from transient and statistical perspectives. Its impact on tractive energy consumption is then evaluated from individual and platoon perspectives. Results Our data suggest that unlike human drivers, ACC followers lead to string instability. Their inability to absorb the speed overshoots may partly be explained by their high responsiveness from a control theory perspective. Statistical results might imply the followers in the automated or mixed traffic flow generally perform worse in reproducing the driving style of the preceding vehicle. On the individual level, ACC followers have tractive energy consumption 2.7–20.5% higher than those of human counterparts. On the platoon level, the tractive energy values of ACC followers tend to consecutively increase (11.2–17.3%). Conclusions In general, therefore, ACC impacts negatively on tractive energy efficiency. This research provides a feasible path for evaluating the energy impact of ACC in real-world applications. Moreover, the findings have significant implications for ACC safety design when handling the stability-responsiveness trade-off. </jats:sec

Fuel consumption and CO2 emissions of passenger cars over the New Worldwide Harmonized Test Protocol

AbstractIn 2014 the United Nations Economic Commission for Europe (UNECE) adopted the global technical regulation No. 15 concerning the Worldwide harmonized Light duty Test Procedure (WLTP). Having significantly contributed to its development, the European Commission is now aiming at introducing the new test procedure in the European type-approval legislation for light duty vehicles in order to replace the New European Driving Cycle (NEDC) as the certification test.The current paper aims to assess the effect of WLTP introduction on the reported CO2 emissions from passenger cars presently measured under the New European Driving Cycle and the corresponding test protocol. The most important differences between the two testing procedures, apart from the kinematic characteristics of the respective driving cycles, is the determination of the vehicle inertia and driving resistance, the gear shifting sequence, the soak and test temperature and the post-test charge balance correction applied to WLTP. In order to quantify and analyze the effect of these differences in the end value of CO2 emissions, WLTP and NEDC CO2 emission measurements were performed on 20 vehicles, covering almost the whole European market. WLTP CO2 values range from 125.5 to 217.9g/km, NEDC values range from 105.4 to 213.2g/km and the ΔCO2 between WLTP and NEDC ranges from 4.7 to 29.2g/km for the given vehicle sample. The average cold start effect over WLTP was found 6.1g/km, while for NEDC it was found 12.3g/km. For a small gasoline and a medium sized diesel passenger car, the different inertia mass and driving resistance is responsible 63% and 81% of the observed ΔCO2 between these two driving cycles respectively, whereas the other parameters (driving profile, gear shifting, test temperature) account for the remaining 37% and 19%

An experimental study on the impact of biodiesel origin on the regulated and PAH emissions from a Euro 4 light-duty vehicle

This study investigates the impact of mid-high biodiesel blends on the criteria and PAH emissions from a pick-up diesel vehicle. The vehicle was a Euro 4 (category N1, subclass III) compliant common rail light duty vehicle fitted with a diesel oxidation catalyst. Emission and fuel consumption measurements were performed on a chassis dynamometer using constant volume sampling (CVS) technique, following the European regulations. All measurements were conducted over the NEDC and Artemis driving cycles. Aiming to evaluate the fuel impact on emissions, a soy-based biodiesel, a palm-based biodiesel, and an oxidized biodiesel obtained from used frying oils were blended with an ultra low sulfur diesel at proportions of 30%, 50% and 80% by volume. CO2 emissions and fuel consumption exhibited increases with biodiesel over all driving conditions which ranged up to 5%. NOx emissions were found to be above the Euro 4 limit and increased with biodiesel between 5% and 10% except for the blends prepared with the palm-based methyl ester. The emissions of PM, HC, and CO decreased with the addition of biodiesel reaching maximum reductions in the order of 10%, 30% and 20% respectively; however, some increases were observed over the NEDC which may be attributed to cold-start. Sharp increases in most PAH, nitro-PAH and oxy- PAH compounds were observed with the application of biodiesel. These increases were particularly noticeable with the use of the oxidized blends, a phenomenon that it is related with the type and quality of this fuel. The emissions were also affected by the operating conditions of the engine. It was found that most PAH compounds were decreased as the mean speed and load of the driving cycle increased.JRC.F.9-Sustainable Transport (Ispra

An experimental study on the impact of biodiesel origin on the regulated and PAH emissions from a Euro 4 light-duty vehicle

This study investigates the impact of mid-high biodiesel blends on the criteria and PAH emissions from a pick-up diesel vehicle. The vehicle was a Euro 4 (category N1, subclass III) compliant common rail light duty vehicle fitted with a diesel oxidation catalyst. Emission and fuel consumption measurements were performed on a chassis dynamometer using constant volume sampling (CVS) technique, following the European regulations. All measurements were conducted over the NEDC and Artemis driving cycles. Aiming to evaluate the fuel impact on emissions, a soy-based biodiesel, a palm-based biodiesel, and an oxidized biodiesel obtained from used frying oils were blended with an ultra low sulfur diesel at proportions of 30%, 50% and 80% by volume. CO2 emissions and fuel consumption exhibited increases with biodiesel over all driving conditions which ranged up to 5%. NOx emissions were found to be above the Euro 4 limit and increased with biodiesel between 5% and 10% except for the blends prepared with the palm-based methyl ester. The emissions of PM, HC, and CO decreased with the addition of biodiesel reaching maximum reductions in the order of 10%, 30% and 20% respectively; however, some increases were observed over the NEDC which may be attributed to cold-start. Sharp increases in most PAH, nitro-PAH and oxy-PAH compounds were observed with the application of biodiesel. These increases were particularly noticeable with the use of the oxidized blends, a phenomenon that it is related with the type and quality of this fuel. The emissions were also affected by the operating conditions of the engine. It was found that most PAH compounds were decreased as the mean speed and load of the driving cycle increased. © 2011 Elsevier Ltd. All rights reserved

Effect of biodiesel origin on the regulated and PAH emissions from a modern passenger car

This study investigates the impact of low concentration biodiesel blends on the regulated and polycyclic aromatic hydrocarbon (PAH) emissions from a modern passenger vehicle. The vehicle was Euro 4 compliant fitted with a direct injection common-rail diesel engine and a diesel oxidation catalyst. Emission and fuel consumption measurements were performed on a chassis dynamometer using constant volume sampling (CVS) technique, following the European regulations. All measurements were conducted over the type approval New European Driving Cycle (NEDC) and the real-traffic based Artemis driving cycles. Aiming to evaluate the fuel impact on emissions, a soy-based, a palm-based, and a rapeseed oil based biodiesel were blended with an ultra low sulphur diesel at proportions of 10, 20, and 30 % by volume. The experimental results revealed that emissions of PM, HC and CO decreased with biodiesel over most driving conditions. Some increases were observed over the NEDC which may be attributed to the cold-start effect and to certain fuel characteristics. NOx emissions were found higher with biodiesel especially during Artemis operation. CO2 emissions and fuel consumption followed similar patterns and increased with biodiesel. PAH emissions presented discordant results, leading to the hypothesis that the influence of biodiesel source material was particularly strong on the formation of these pollutants. Both increases and decreases were observed in PAH, nitrated PAH and oxygenated PAH compounds with the use of biodiesel blends. Overall, biodiesel at low blending ratios may adversely impact toxic emissions and ultimately alter urban air quality. © 2011 SAE International.JRC.F.8-Sustainable Transport (Ispra

Effect of biodiesel origin on regulated and particle-bound PAH (polycyclic aromatic hydrocarbon) emissions from a Euro 4 passenger car

This study investigates the impact of low concentration biodiesel blends on the regulated and particle-bound polycyclic aromatic hydrocarbon (PAH) emissions from a modern passenger car. Emissions measurements were performed on a chassis dynamometer using constant volume sampling technique, following the European regulations. All measurements were conducted over the New European Driving Cycle (NEDC) and the Artemis driving cycles. Aiming to evaluate the fuel impact on emissions, a soy-based, a palm-based, and a rapeseed oil based biodiesel were blended with diesel fuel at proportions of 10, 20, and 30% by volume. The emissions of PM, HC, and CO decreased with biodiesel over most driving conditions. Some increases were observed over the NEDC, which may be attributed to the cold-start effect and to certain fuel characteristics. NOx emissions increased with biodiesel and strongly were dependent to the degree of unsaturation of the fuel. CO2 emissions and fuel consumption followed similar patterns and increased with biodiesel. PAH emissions presented discordant results, leading to the hypothesis that the influence of biodiesel source material was particularly strong on the formation of these pollutants. Both increases and decreases were observed in PAH, nitrated PAH and oxygenated PAH compounds with the use of biodiesel blends. © 2011 Elsevier Ltd

The impact of soy-based biodiesel on PAH, nitro-PAH and oxy-PAH emissions from a passenger car operated over regulated and nonregulated driving cycles

This study explores the impact of neat soy-based methyl ester and its 50% v/v blend with low sulphur automotive diesel on PAH, nitro-PAH and oxy-PAH emissions of a Euro 2 compliant diesel passenger car tested on a chassis dynamometer. Emission measurements were evaluated for the certification NEDC, a hot-start UDC (urban part of NEDC) and the non-legislated Artemis driving cycles which simulate urban, rural and highway driving conditions in Europe. Overall, 16 PAHs, 4 nitro-PAHs and 6 oxy-PAHs were determined in the exhaust. The results obtained, showed that PAH emissions decreased with the addition of biodiesel during all driving modes. However, their nitrated and oxygenated products were found to increase with biodiesel compared to diesel fuel. The use of pure biodiesel led in some increases in PAH emissions when compared to its 50% blend. PAH emissions were also found to be adversely influenced by cold-start conditions and certain fuel properties. © 2010 Elsevier Ltd. All rights reserved

Impact of straight vegetable oil-diesel blends application on vehicle regulated and non-regulated emissions over legislated and real world driving cycles

Straight vegetable oil (SVO) has been considered as a possible alternative to fossil diesel-engine fuel since the development of diesel engines. In Europe, SVOs achieved a measurable share in biofuels market reaching 4%. This study attempts to identify the impact of untreated SVO application on fuel consumption and emissions, regulated and non-regulated, on a Euro 3 common rail diesel passenger car. Three different vegetable oils (cottonseed, sunflower, and rapeseed) were blended with diesel fuel, on a 10-90% v/v ratio each. Chassis dynamometer measurements were conducted including both regulated and non-regulated pollutants. In the case of rapeseed oil-diesel blend, carbonyl compounds (10 aldehydes and ketones) were investigated. In addition to the legislated procedure (NEDC), the Artemis driving cycles were used for quantifying the fuels&apos; impact over realistic driving conditions. Results indicate that all blends have limited effects on gaseous pollutants and vehicle performance. Statistically significant increases on CO2, CO and HC were recorded over NEDC in the order of 3, 39 and 31%. Reductions were observed on PM emissions particularly for the sunflower oil blends, while NOx remained at baseline levels. Comparison with the emission levels measured when using esterified fuels of the same feedstocks suggests that SVO presence does not affect engine exhaust in the same way as biodiesel. The vegetable oil presence in the fuel appeared to suppress the formation of nucleation mode particles. Straight rapeseed oil increased carbonyl compound emissions over all cycles tested and resulted in higher acroleine/acetone presence in the carbonyl compound composition. © 2011 Elsevier Ltd