Publications

Abstract

Recent days the tampering procedure, often known as unauthorized and deliberate alteration of vehicle parts, has an impact on many vehicle functions. In reality, contemporary tampering methods are becoming more sophisticated and are able to mimic authentic signals using unique control mechanisms. The main motivations among others of tampering is the increase of engine output and the manipulation of the Emission After Treatment System in order to save money by preventing the need for costly repairs for malfunctioning diesel engine emissions control systems. Along with numerous other nations, the European Commission predicted an increase in the number of modified vehicles. An information system for identifying and notifying potential tampering or inadequate engine performance/maintenance issues with a vehicle is presented in this paper. The basic idea is based on comparing vehicle parameter values retrieved from On-Board Diagnostic with factory values or vehicle performance values recorded by independent agencies. Read more.

Presented at the ITS European Congress 2023

Authors: Nikos Dimokas, Dimitris Margaritis, Andrew Winder.

Abstract

The impact of road transport on local air quality and its share of total greenhouse gases is considerable. Although there are efforts toward the development and commercialization of green and electric vehicles, it is necessary also to optimize the emissions of the existing fleet. As part of the MODALES project, a mobile application has been developed to guide the driver for optimum emission driving style including tyre and brake particle emissions. As part of the application, an innovative score calculation system has been developed taking into account tyre and brake emissions, using a weighted aggregate emission value. Parametric weights have been selected in line with air quality and cost of health. Read more.

Presented at the ITS European Congress 2023

Authors: Engin Özatay, Orhan B. Alankuş.

Abstract

PM10 emissions generated from the brake wear of passenger car per braking event during three test driving cycles (WLTP, LACT, and WLTP-Brake) were studied using a finite element analysis (FEA) approach in combination with the relationship among the mass emitted rate of airborne particles versus local contact pressure and sliding speed. In addition, PM10 emissions were measured per braking event during the WLTP-Brake cycle on a brake dynamometer using an electrical low-pressure impactor (ELPI+) to validate the proposed FEA approach. The simulated and experimental results for WLTP-Brake illustrated that the proposed simulation approach has the potential to predict PM10 from brake wear per braking event, with an R2 value of 0.93. The FEA results of three test driving cycles showed that there was a gradient rise in pad wear on both sides from the inner to outer radii. The simulated PM10 emission factors during the WLTP, LACT, and WLTP-Brake were 7.9 mg km-1, veh-1, 9.8 mg km-1 veh-1, and 6.4 mg km-1 veh-1, respectively. Among three test driving cycles, the ratio of PM10 to total brake wear mass per braking event was the largest for the LACT, followed by WLTP and WLTP-Brake. From a practical application perspective, reducing the frequency of high-speed braking may be an effective way to decrease the generation of PM10 emissions. Read more.

Published on Chemosphere

Authors: Ye Liu, Haibo Chen, Chuhan Yin, Matteo Federici, Guido Perricone, Ying Li, Dimitris Margaritis, Yang Shen, Junhua Guo, Tangjian Wei.

Abstract

Tyre wear generates not only large pieces of microplastics but also airborne particle emissions, which have attracted considerable attention due to their adverse impacts on the environment, human health, and the water system. However, the study on tyre wear is scarce in real-world driving conditions. In the present study, the left-front and leftrear tyre wear in terms of volume lost in mm3 of 76 taxi cars was measured about every three months. This study covered 22 months from September 2019 to June 2021 and included more than 500 measurements in total. Some of the data was used to evaluate the effects of vehicle type and tyre type on tyre wear. In addition, a machine learning method (i.e., Extreme gradient boosting (XGBoost)) was used to probe the effect of driving behaviour on tyre wear by monitoring
real-time driving behaviour. The current statistical results showed that, on average, the tyre wear was 72 mgveh−1 km−1 for a hybrid car and 53 mg veh−1 km−1 for a conventional internal combustion engine car. The average tyre wear measured for a taxi vehicle configuration featuring winter tyres was 160 mg veh−1 km−1, which was 1.4 and 3.0 times as much as those with all-season tyres and summer tyres, respectively. The wear rate of left-front tyres was 1.7 times higher than that of left-rear tyres. The XGBoost results indicated that compared to driving behaviour, tyre type and tyre position had more important effects on tyre wear. Among driving behaviours, braking and accelerating events presented the most considerable impact on tyre wear, followed by cornering manoeuvres and driving speed. Thus, it seems that limiting harsh braking and acceleration has the potential to reduce tyre wear significantly. Read more.

Published on Science of the Total Environment

Authors: Ye Liu, Haibo Chen, Sijin Wu, Jianbing Gao, Ying Li, Zihao An, Baohua Mao, Ran Tu, Tiezhu Li.

Abstract

Automobile emissions are significantly dependent on the after- treatment system performance,  which  is  partly  determined  by  exhaust  temperature.  Regarding diesel passenger cars, after- treatment systems generally include diesel oxidation catalyst (DOC), diesel particulate filter (DPF), and selective catalytic reduction (SCR). The layouts affect their temperature variations because of the heat loss and thermal capacity of tailpipes and after- treatment systems. As for the origi-nal layout of DOC+DPF+SCR, nitrogen oxides (NOx) emissions are the main concerns  of  diesel  vehicle  emissions,  especially  under  cold- start  conditions. Ammonia  Creation  and Conversion  Technology (ACCT)  system  shows  excel-lent performance of reducing cold- start NOx emissions; additionally, the damage costs of individual exhaust emissions are different greatly, which may change the priority of emission reductions when considering monetary penalty. In this article, the impacts of the after- treatment system layouts on the exhaust emis-sion reductions were investigated based on a diesel passenger car; additionally, SCR and ACCT systems as the De- NOx devices were adopted individually in cor-responding scenarios; the after- treatment system layouts were assessed from the viewpoints of both emission factors and monetary penalty. The results indicated that the ACCT system presented much better NOx reduction effectiveness than SCR system over different layouts. NOx reduction efficiency was very sensitive to vehicle operation conditions over the upstream layouts of NOx reduction de-vices. The layout- 1 of DOC+ACCT+DPF showed the lowest global emission fac-tors from the diesel passenger car. DPF was much easier to achieve regeneration under the original layout conditions due to its shortest distance to the engine. The layout- 2 of ACCT+DOC+DPF had the minimum monetary penalty factor of exhaust emissions from this diesel passenger car. Read more.

Published on Energy Science & Engineering

Authors: Jianbing Gao, Haibo Chen, Ye Liu, Ying Li.

Abstract

Traffic and vehicle simulations are often developed individually. However, vehicle performance is heavily affected by traffic conditions. Cosimulations of traffic and vehicle under real-road situations can reflect the semi-real-world performance of vehicles, with traffic conditions being taken into considerations. This paper proposed an approach to combine the traffic and vehicle simulations that are realized by simulation of urban mobility (SUMO) and GT-Suite software, respectively. Read more.

Published on Energy Science & Engineering

Authors: Jianbing Gao, Haibo Chen, Kaushali Dave, Junyan Chen, Dongyao Jia.

Abstract

Road transportations still play a dominant role in goods delivery, and driving behaviours significantly affect the fuel economy of heavy-duty trucks. Plenty of fossil fuel is wasted as a result of unreasonable driving behaviours even in the case of highly experienced drivers. The objective of this paper is to analyse drivers’ behaviours over two segments of motorways and estimate the potential benefits of fuel saving caused by a change in driving habits during national and international goods delivery. Drivers’ habits on motorways change depending on the road situations. In the acceleration process, the fuel consumption rates are huge even under low-speed conditions. The truck fuel consumption rates are
exaggerated by positive road slopes, but still dominated by acceleration. Accelerations are generally in normal distributions, with the median value being approximately 0.5 m/s2. The speed ranges corresponding to each gear enlarge with the increase in gear number. The potentials of annual fuel saving for parts of European Union countries are nearly 2 3 106 m3 by adopting proper driving behaviours.vely. Read more.

Published on Jounrnal of AUTOMOBILE ENGINEERING

Authors: Jianbing Gao, Haibo Chen, Kaushali Dave, Junyan Chen, Ying Li, Tiezhu Li and Biao Liang.

Abstract

The switch to electric vehicles (EVs) has been incentivised by governments all over the world to reduce the use of fossil fuels and improve air quality. However, whether such a move could effectively lower the levels of pollutants as much as expected is still controversial. This study estimates the impact values of exhaust and nonexhaust emissions emitted from internal combustion engine vehicles (ICEVs) and their equivalent EVs from an economic-environmental perspective, expressed as monetary impact values, so as to ascertain the environmental effect of the switch to equivalent EVs from ICEVs. These monetary impact values were calculated according to the emission factors and damage costs of these pollutants. The results indicate that the particulate matter (PM) monetary impact values of equivalent EVs may exceed those of ICEVs, which depends primarily on the extent of regenerative braking and road type. The monetary impact values of total pollutants decrease for the move from diesel passenger cars to their equivalent EVs with 0% regenerative braking. For the conversion of petrol passenger cars to their equivalent EVs with 0% regenerative braking, however, the total monetary impact values increase on both urban and rural roads. These results can be useful for the economic-environmental assessment of vehicle exhaust and non-exhaust emissions. Read more.

Published on Journal of Cleaner Production

Authors: Ye Liu, Haibo Chen, Ying Li, Jianbing Gao, Kaushali Dave, Junyan Chen, Tiezhu Li,
Ran Tu

Abstract

Nitrogen oxides (NOx) and particulate number (PN) emissions are the main concerns of the passenger cars in the real-world driving. NOx and PN emissions are greatly dependent on the driving behaviors which differ significantly between standard driving cycles and real-world driving. However, the significant contribution regions (short durations corresponding to high proportions of total emissions) of NOx and PN emissions regarding different driving behaviors (e.g. vehicle speed and acceleration) are still uncovered. NOx20% and NOx50% refer to instantaneous NOx emission rates when NOx emission rates are ranked from high to low level where the sums of NOx emission rates being higher than NOx20% and NOx50% correspond to 20% and 50% of total NOx emissions, respectively. t20% and t50% are corresponding durations where NOx emission rates are higher than NOx20% and NOx50%. In this paper, three Euro-6 compliant direct injection gasoline passenger cars and a diesel passenger car are tested in a real-world driving trial in which nineteen drivers are involved. Novel key performance indicators with reference to the regimes of specific NOx and PN contributions to total emissions are defined. Instantaneous NOx and PN emissions are monitored using a portable emission measurement system (PEMS) in the test. The results indicate that the maximum and minimum average speed over the four cars being approximately 32.3 km/ h s and 42.6 km/h, respectively. Average PN emission factor of the diesel car is the lowest among the four given cars. Average t20% and t50% corresponding to NOx20% and NOx50% are lower than 3% and 12%, respectively, for all the passenger cars; additionally, these two parameters show the same pattern. The corresponding t20% and t50% variations of the Euro-6a gasoline car and the diesel car are much lower than the other two. Average acceleration corresponding to 20% and 50% of total NOx  emissions for the given diesel car is approximately 1.25 m/s2 and 0.6 m/s2, respectively, being much higher than that of the other three gasoline cars (lower than 1 m/s2 and 0.4 m/s2 respectively) over the specific driving route and drivers. The average PN20% and  N50% of the given diesel car are approximately 7 × 107#/s and 3 × 107#/s respectively, being much lower than the three given gasoline cars (higher than 8 ×109#/s and 2 ×109#/s respectively) under the given test conditions; the corresponding t20% and t50% are lower than 4% and 17% respectively for all the three gasoline cars. Read more.

Published on Journal of Hazardous Materials

Authors: Jianbing Gao, Yufeng Wang, Haibo Chen, Juhani Laurikko, Ye Liu, Ari-Pekka Pellikka,
Ying Li

Abstract

This study implemented real-world tests in Nanjing, China formeasuring emission factors (EFs) of air pollutants, including Carbon Monoxide (CO), Hydrocarbon (HC), Nitrogen Oxides (NOx), and Particulate Matter (PM) from ten construction machines in three operational modes (idling, moving, and working) with a Portable Emission Measurement System. The idling mode shows the least variation of EFs, and its average CO EFs can be higher than the moving and working modes by 43% and 34%, respectively. The working mode generates the highest emission for all other pollutantswith the highest variation. The EFs suggested by the Guide (an official guidebook for developing emission inventory in China) are in general lower than the measured EFs, and the gap becomes larger for older machines. The EFs of CO, NOx, and PM of China Stage II machines are 24%, 120%, and 66% higher than those of the Guide, respectively. The differences go up as high as 126%, 1066%, and 559% for China Stage I machines, indicating the upgrade of engine technology from Stage I to Stage II, as well as the effect of machine deterioration. The result of this study reveals the effectiveness of stringent emission standards in controlling. Read more.

Published on Science of the Total Environment

Authors: Ran Tu, Tiezhu Li, Chunsheng Meng, Jinyi Chen, Zhen Sheng, Yisong Xie, Fangjian Xie, Feng Yang,
Haibo Chen, Ying Li, Jianbing Gao, Ye Liu

Abstract

This paper evaluates the effect of the electrification of the small, medium, and large internal combustion engine (ICE) passenger cars on the levels of total particulate matter (PM). The total mean PM10 and PM2.5 emission factors (EFs) on urban, rural, and motorway roads are in the range of 26.13 􀀀 39.57 mg km􀀀 1 veh􀀀 1 and 13.39 􀀀 18.44 mg km􀀀 1 veh􀀀 1, respectively, from small to large ICE passenger cars. Correspondingly, the total mean PM10 and PM2.5 non-exhaust EFs on urban, rural, and motorway roads range from 27.76 to 43.43 mg km􀀀 1 veh􀀀 1 and 13.17 –19.24 mg km􀀀 1 veh􀀀 1 from equivalent small to large electric vehicles (EVs) without regenerative braking. These results show that the total non-exhaust PM from the equivalent EVs may exceed all PM from ICE passenger cars, including exhaust particle emissions, which are dependent mainly on the extent of regenerative braking, followed by passenger car type and road type. PM10 EFs for equivalent EVs without regenerative braking on urban, rural, and motorway roads are all higher than those from ICE cars. As for PM2.5, most of the equivalent
EVs require different extents of regenerative braking to reduce brake emissions to be in line with all particle emissions from relative ICE cars. Read more.

Published on Journal of Hazardous Materials

Authors: Ye Liu, Haibo Chen, Jianbing Gao, Ying Li, Kaushali Dave, Junyan Chen,
Matteo Federici, Guido Perricone

Abstract

With emission standards becoming stricter, nitrogen oxides (NOx) and particle number (PN) emissions are the main concerns of modern passenger cars, especially for the real-world driving. In this paper, two direct injection (DI) petrol passenger cars and a diesel passenger car are tested on the same routes, driven by the same driver. Instantaneous NOx and PN emissions are monitored by a portable emission measurement system (PEMS) in the tests. During the real-world driving, the exhaust temperatures of the two petrol cars are sufficiently high to ensure high efficiency of three-way catalysts (TWCs). On the other hand, the exhaust temperatures of the diesel car in some sections of the route are lower than the crucial light-off temperature of the selective catalytic reduction (SCR) below which its effectiveness in NOx reduction would be much affected. NOx and PN concentrations are low during motorway driving for the petrol passenger car equipped with a gasoline particulate filter (GPF); however, they are high and change frequently in the whole  journey for the petrol passenger car without a GPF. NOx emission factors are quite low over most of the driving sections for the diesel car, but some significant high peaks are observed in the acceleration process. NOx emission distributions over speed and acceleration are similar for both petrol cars; and they differ significantly from the diesel counterpart. Particle size from the diesel car is the largest, followed by the petrol car with a GPF. Read more.

Published on Science of the Total Environment

Authors: Jianbing Gao, Haibo Chen, Ye Liu, Juhani Laurikko, Ying Li, Tiezhu Li, Ran Tu.

Abstract

Nitrogen oxides (NOx) emissions from passenger cars are significantly dependent on after-treatment techniques, cold start conditions, and driving behaviours. The widely-used selective catalytic reduction (SCR) technique has low effectiveness of reducing NOx emissions during the cold start period or at low speeds. As a new technique, ammonia creation and conversion technology (ACCT) system can further decrease NOx emissions to achieve cleaner travelling. The correlations between driving behaviours and NOx emissions are different for vehicles equipped with SCR and ACCT systems over cold start and warm start driving cycles. In this paper, the effect of SCR and ACCT systems on the correlations between driving behaviours and NOx emissions were explored based on worldwide harmonized light vehicle test cycles (WLTC). The results indicated that vehicle fuel consumption rates almost linearly increased with acceleration when the acceleration was higher than
0.5 m/s2. For cold start situations, vehicle speed range of 55 km/h~ 100 km/h presented the lowest NOx emission factors over SCR and ACCT scenarios. SCR efficiency was lower than 60% for the vehicle speed range of 25 km/h~ 40 km/h, and the efficiency of ACCT system was higher than 65% in the corresponding speed range. Regarding the warm start scenarios, average catalyst efficiency was higher than 80% for SCR system over the speed range of 25 km/h~ 40 km/ h, and ACCT efficiency was higher than 95% for all the speed and acceleration ranges. Applications of ACCT systems provided a possibility of meeting stricter emission regulations, and the relationships between driving behaviours and NOx emissions provided the guidance for eco-driving to achieve cleaner travelling. Read more.

Published on Journal of Cleaner Production

Authors: Jianbing Gao, Haibo Chen, Ye Liu, Ying Li, Tiezhu Li, Ran Tu, Biao Liang,
Chaochen Ma.