Numerical and experimental evaluation of technological solutions for the compliance of environmental legislation in light-duty passenger vehicles

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1 Numerical and experimental evaluation of technological solutions for the compliance of environmental legislation in light-duty passenger vehicles Ana Margarida Neves Taborda* *Department of Mechanical Engineering, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais 1, Lisboa, Portugal; Abstract: This work includes an experimental and a numerical analysis to assess the impacts of fuel efficiency and NO x emission reduction technologies on a light-duty passenger vehicle. The solutions analyzed were Stop/Start, vehicle mass reduction up to kg, drag coefficient reduction, variation of tyre dimension, as well as SCR and Lean NO x Trap systems. For this purpose, a reference EURO 6 diesel vehicle was monitored under real-world driving conditions with a PEMS and the experimental data obtained, after processed, was used to build engine maps of fuel use and NO x emission on AVL Cruise software. The results obtained with Cruise were firstly validated with the experimental data (with errors up to 10,6% on fuel and 17,5% on NOx) and then the solutions implemented were tested individually and simulated on 48 real-world driving cycles. The results pointed to Stop/Start, mass reduction of kg and SCR as the most effective solutions in reducing fuel consumption and NO x emission up to 14,6% and 57,5%, respectively. The combination of these technologies was tested and the results showed up to 17% of fuel savings and a maximum NO x reduction of 58%. Despite all the efforts, real-world driving presents NO x emissions not yet compliant with standards, indicating the need for new strategies in order to face the environmental challenges. Key-Words: Diesel vehicles; AVL Cruise; Vehicle monitoring; NO x emissions; Fuel efficiency. 1. INTRODUCTION The transportation sector was responsible for around 30% of the world s energy consumption in 2013, of which 75% were pointed to road transportation, and with increasing expectations [1]. The increasing number of road vehicles has been contributing to the degradation of air quality, particularly in urban areas [2], due to the general use of fossil fuels on internal combustion engines (ICE). Around 90% of road vehicles use fossil fuels, resulting in the emission of pollutants, such as carbon monoxide (CO), nonmethane volatile organic compounds (NMVOC), nitrogen oxides (NO x ) and particulate matter (PM), which are known for atmospheric degradation but also for their harmful effects on human health [1, 3]. Moreover, the increasing emission of carbon dioxide (CO 2 ) into the atmosphere, released by ICE, also raises environmental concerns since it contributes to climate changes [4]. Considering that around 53% of the European Union (EU) passenger car fleet are Diesel vehicles, which are the main source of NO x and PM emissions, the problem worsens [5]. To address the former issues, several entities and countries made commitments, agreements and legislation in order to car makers meet target values for CO 2 and pollutant emission limits. The pollutant emission limit values were introduced in 1992 with EURO 1 standard and became more stringent over the years, being now EURO 6 the current standard [6]. Vehicle certification is performed by private entities in a controlled environment on a chassis dynamometer, following the procedures of EURO standards. The test cycles are standardized and aim to simulate specific driving conditions. In EU the cycle currently in use is the New European Driving Cycle (NEDC) which consists of an urban part (low loads and velocities) and an extra-urban segment (higher velocities and loads), reaching a top speed of 120 km/h and an average speed of 34 km/h [7]. However, the certification test representativeness is being questioned by several studies claiming great discrepancies between test certification results and real-world emissions [8 10], having major deviations being recorded in CO 2 and NO x values, the latter regarding Diesel vehicles, due to its reduced coverage of the engine operational range, existence of flexibilities (such as the possibility of manufacturers to take off extra equipment from the test vehicle to reduce weight), etc. [10, 11]. In order to overcome these issues, new sets of certification procedures are being prepared. One of the attempts to increase test representativeness is the introduction (in 2017) of a new test cycle, the World Harmonized Light Vehicles Test Procedure (WLTP), based on real data from different world regions. The new test procedures are set to be stricter than the current ones, while the new test cycle is more transient 1

2 and demanding than NEDC to better simulate on-road conditions [8, 11, 12]. Still, it is a chassis dynamometer test cycle and continues to have the drawbacks associated with this type of test, therefore the European Commission has agreed with a new certification package, consisting on vehicle on-road monitoring, the Real Drive Emissions (RDE) to be implemented in 2017, as a complementary certification measure. RDE foresees a conformity factor between the laboratory results and on-road values of 2.1 (110%) until 2019, which will be reduced to 1.5% (50%) until 2021, and then it will be abolished [13, 14]. Given the tightening of the legislation and vehicle type approval tests, vehicle manufacturers have to draw new strategies and incorporate more solutions in their vehicles in order to achieve the expectations. There are already several technologies and solutions that contribute to higher efficiency and to lower the emissions, some requiring considerable investment, such as hybrid and electric vehicles, and others, more widespread at reasonable costs [5, 15] namely, Stop/Start, weight reduction, improved aerodynamics and NO x conversion technologies. Stop/Start is a step towards vehicle hybridization and is present in almost all new vehicles, cutting out idle consumption. It is estimated to allow for a fuel saving of around 5,3% overall [16], and 12,2% in urban driving [17]. Reductions of 10% in vehicle weight translate into a CO 2 reduction between 2,7 to 3,6% and as the weight is reduced, CO 2 decreases in a linear way, according with [18]. Other sources estimate that a kg reduction can save around 0,15-0,38 l/km or up to 1 l/km of fuel [19, 20]. The effects of drag forces are more important at high velocities, but in overall some studies point towards fuel saving of about 3% for a 20% C D reduction [21] and even to a CO 2 reduction of 0,6-1,2% to 1,2-2,4% for a 5 to 10% reduction in the aerodynamic drag over the NEDC cycle [18]. Regarding exhaust gas treatment in Diesel vehicles, the main challenge is to control NO x emissions and for that purpose there are two main technologies available to comply with EURO 6 standards: SCR which reduces NO x by injecting an urea solution and LNT, an adsorber which traps NO x molecules which regenerates from time to time (reduces NO x and expels it). There are 2 types of commercial SCR: a standard SCR and a fast SCR. The difference between them is the reaction that occurs, where the standard uses O 2 as the reducing agent and the fast uses NO 2 to reduce NO. So as the standard needs to reduce NO 2 into NO and then to N 2 with help from oxygen, the fast SCR skips a step, having higher conversion efficiency in a wider range of the functioning temperature, which ranges between ~ 250 C to 600 C[22]. There are also different types of LNTs with different conversion efficiencies depending on the quantity of platinum in the substrate [22]. Both technologies are commercialized but have different performances according with the driving context. In general, LNTs are best suited for urban driving as they require lower temperatures to operate but at high loads they can saturate due to their limited storage capacity [23]. As for SCRs, they have particularly good results at high loads and high velocity cycles, with 95% efficiency [5, 23]. Even though the number of studies on the impact of these technologies is considerable, there are little literature based on real-world driving under different driving contexts and even fewer trying to understand the effect of the combination of different solutions. Consequently, the focus of this paper is to address the impacts on fuel consumption and NO x emission of Stop/Start systems, weight reduction, drag coefficient (C D ) reduction, transmission variation due to tyre dimension variation and exhaust gas treatment such as selective catalytic reduction (SCR) and lean NO x traps (LNT). 2. METODOLOGY 2.1 On-road monitoring The experimental, on-road tests were performed on a EURO 6 Diesel vehicle, representative of the Portuguese average car fleet. It has a 4 cylinder, inline, turbocharged, 1.5 Diesel engine ( rpm) and a 6 speed manual transmission. The vehicle curb weight is 1345 kg and C D =0,3, with integrated emission and fuel reduction technologies to achieve the EURO 6 standard, such as EGR, particulate filter and Stop/Start. However, the Stop/Start system was shut off during on-road tests to assure the correct operation of the 12V battery, which powered equipment installed on-board. The on-road tests were performed with a portable laboratory composed with an OBD scanner (OBDKey), GPS with barometric altimeter (GPSMap 76CSx) to measure altitude, exhaust gas analyzer (Horiba 2

3 MEXA-720 NO x ) to measure NO x concentration and a laptop with specific LabView program to collect and synchronize the data at 1Hz. The vehicle was monitored for 7499 seconds, approximately 2 hours, and was driven by a single driver through a specified route, including urban and extra-urban cycles, and subject to different driving styles. With this experiment it was intended to test different engine operation conditions, through the adequacy of the driving style, in order to collect a wide range of operation points, from high to low loads and speeds, including data from climbing performance. 2.2 Data collection and processing Data was collected for every second and stored by the LabView program, which was then downloaded for processing. The route was divided into 3 cycles according with the following characteristics: Cycle 1 Distance: 19 km; Average velocity: 29 km/h; Mix cycle: urban and extra-urban part; Cycle 2 - Distance: 25 km; Average velocity: 58,7 km/h; Mix cycle; Cycle 3 - Distance: 19 km; Average velocity: 23 km/h; Urban cycle. Since the fuel consumption was not directly measured, it was necessary to perform calculations based on the information of the O 2 concentration collected by the analyzer in the exhaust gas. Equation 1 gives the mass fuel burnt, in g/s, and it was obtained from a mass balance to the diesel combustion reaction in the presence of excess of air. m fuel = m arobd ( ) (14,5 + 73,52 %O 2 1 4,47 %O ) (32 + 3,76 28) 2 Equation 1 Also the NO x concentration (in ppm) needs to be converted into g/s. The conversion is represented on Equation 2 and is obtained by the chemical balance of diesel combustion in excess of air. ppmno x 10 6 (73,52 + 4,76 73,52 %O 2 1 4,76 %O ) 2 m arobd 1 ppmno Equation 2 x m NOx = 10 6 (14,5 + 73,52 %O 2 1 4,47 %O ) (32 + 3,76 28) 2 In order to have a correct mapping of the vehicle performance, some of the data points collected were filtered to overcome some delays resulting from OBD operation. From the continuous data points, after filtering the outliers, the fuel consumption and NO x emission maps, as function of engine load and speed, were obtained by considering only certain ranges of engine speed and iterating and refining the data. Figure 1- Torque as a function of engine speed with representation of isolines of fuel consumption in kg/h Figure 2- Torque as a function of engine speed with representation of isolines of NO x emission in kg/h These maps show how the engine is governed in terms of fuel consumption (fig.: 1) and NO x emissions (fig.: 2) and are, therefore, essential to model the vehicles real engine behaviour in the AVL Cruise software. 3

4 2.3 Vehicle modelling AVL Cruise is a commercial software for vehicle simulation that allows modelling all the vehicle components from the powertrain system to the chassis, as well as a great variety of vehicle configurations from the conventional ICE car to hybrids and heavy duty vehicles [24]. This tool can calculate vehicle fuel consumption and emissions for every kind of driving cycle and driving and braking performance. The methodology used by the program to perform the calculations can either be a forward facing or a backward facing methodology. The first uses a driver model to control the vehicle, simulates the vehicle s behaviour from there and the driving cycle may or may not be fully accomplished, depending on the skills of the driver s model and the vehicle s properties. Backward facing methodology applies reverse engineering by assuming that the driving cycle request was fully achieved and works back by calculating the tractive forces and so on, across all the components until it arrives to the value of the fuel consumed [7]. This method is computationally more efficient and was the one chosen for the calculations because all the cycles were in fact performed under real-world conditions by the reference vehicle or other with a bigger weight-power ratio. In order to build the vehicle model, besides the information from figures 1 and 2 required to model the engine, additional data such as vehicle weight, dimensions, gear ratios, final drive ratio, tire rolling radius, etc. needed to be introduced and was taken from vehicle s manufacturer manual [25]. The software also requires engine loss values to model the exhaust gas temperature, which were iterated until reaching an exhaust temperature curve similar to the typical exhaust temperature curves of the NEDC cycle [26]. 3. RESULTS 3.1 Software validation The first step towards a consistent analysis is the software and vehicle model validation by comparing experimental results with the numerical data obtained from AVL Cruise, regarding fuel consumption and NO x emission for the three cycles from the monitored route. Tables 1 and 2 present a comparison between the experimental results, the results from AVL Cruise model without engine mapping and the results of the vehicle modelled in the numerical tool with the engine characterization (from the information in Figures 1 and 2). Table 1- Comparison of fuel consumption results from the experimental data and the simulation with and without engine characterization, for three monitored cycles. Monitored vehicle Fuel consumption (l/km) Cycle 1 Cycle 2 Cycle 3 Fuel consumption (l/km) Fuel consumption (l/km) 8,1-5,9-6,9 - Cruise model 11,4 41,7 8,2 40,6 10,9 57,1 Characterized model 7,7-4,7 5,2-10,6 6,4-8,0 Table 2- Comparison of NO x emission results from the experimental data and the simulation with and without engine characterization, for three monitored cycles. NO x emission (g/km) Cycle 1 Cycle 2 Cycle 3 NO x emission (g/km) NO x emission (g/km) Monitored vehicle 1,080-0,918-0,733 - Cruise model 1,881 74,2 1,789 94,9 1, ,5 Characterized model 1,077-0,3 0,757-17,5 0,813 10,9 As can be seen from Tables 1 and 2, the Cruise model (which refers to the vehicle modelled on the software without engine characterization from the experimental data) provides results with relative errors between 40-57% in fuel consumption and between % in the NO x emission when compared with on-road data. On the other hand, the characterized model (and the only considered henceforward) has relative errors (in relation to the experimental results) between 4,7-10,6% for fuel consumption and 0,3-4

5 17,5% for NO x emission. This shows the importance of having a well-adjusted model of the engine operation. Cycle 1 has the most approximated results (4,7% error for fuel consumption and 0,3% error for NO x emission), since the characteristics of the cycle include both low and high engine speeds and loads, allowing for a good coverage of all engine operation regions, which helps minimize the errors associated with the engine map characterization. Nevertheless, the deviations presented by cycle 2 and 3 are also quite low (10,6% for fuel and 17,5% for NO x in cycle 2; 8% for fuel and 10,9% for NO x in cycle 3) and in accordance with results from other studies [27]. Considering these results, it can be assumed that both the software and model are reliable and suited to test fuel consumption and emission reduction solutions. 3.2 Fuel consumption and emission reduction technologies impact evaluation The introduction in the model of fuel use and pollutant emission reduction technologies was made individually resulting in 6 different vehicle model configurations: one for Stop/Start, one for mass reduction (held in 5 stages each reducing 20 kg), one for drag reduction (held in two stages), one for tyre variation (2 approved dimensions were tested: ± 2mm radius), another for SCR (1 standard and 1 fast) and the last for LNT (2 types of conversion efficiency). The energy and environmental performance of these solutions was tested for 48 real-world driving cycles taken from a previous study [28]. Of those, 18 were considered urban, 14 mix and 16 extra-urban cycles. Their average features are represented in table 4. Table 3 Average features of the driving cycles, divided by driving context. Time (s) Distance (m) Average velocity (km/h) Maximum velocity (km/h) Average negative acceleration (m/s 2 ) Average positive acceleration (m/s 2 ) Time in idling (%) Altitude (m) Urban Cycles ,8 20,5 76,4-0,60 0, Mix Cycles ,7 43,8 122,4-0,55 0, Extra-urban Cycles ,0 92,0 145,4-0,39 0, The influence of Stop/Start on fuel consumption and NO x emissions is presented on Figure 1. a) b) Figure 1- Influence of Stop/Start on fuel consumption (a) and NO x emission (b) for different driving contexts The results presented in Figure 1 a) show a general reduction of fuel consumption, especially in urban cycles (~ -1 l/km), resulting from the considerable amount of time spent on idling. Also, NO x emission (Figure 1 b)) benefits from the introduction of this system as it follows the fuel reduction trend (-0,05 g/km in urban and -0,03 g/km in mix cycles) with no changes in extra-urban cycles since fuel variation in Fig. 1 a) is insignificant. A kg weight reduction was tested in 5 steps and figures 7 and 8 present the results of the second (-40 kg) and fifth (- kg) stages. 5

6 a) b) Figure 2- Influence of weight reduction on fuel consumption (a) and NO x emission (b) for different driving contexts Weight reduction introduces considerable variations on the energy (Fig. 2 a)) and environmental (Fig. 2 b)) indicators under study, when over 40 kg. Unlike Stop/Start, the effects of this solution affect all of the driving categories in a similar way (~ -0,2 l fuel /km and ~ -0,03 to 0,05 g NOx /km for a kg reduction). For the drag reduction impact simulation, two different values of drag coefficient were considered, corresponding to the lowest values found on the vehicle class considered: C D =0,290; C D =0,285 [29]. a) b) Figure 3 - Influence of drag reduction on fuel consumption (a) and NO x emission (b) for different driving contexts The changes introduced by drag coefficient reduction are minimal (Figure 3 a) and b)) in urban and mix cycles (-0,02 and -0,06 l fuel /km), but on extra-urban cycles it plays a considerable role, reducing consumption by 0,15 l fuel /km, for a C D =0,285. Figure 4- Influence of SCR on NO x emission, for different driving contexts The results presented in Figure 4 show that SCR fast has a better performance than the standard version and, in both cases, the reduction of NO x emission is higher in mix cycles. Considering urban cycles, some show considerable reductions (first quartile has a major drop) but on average SCR effect on these cycles is not very significant due to the low temperatures recorded. On extra-urban cycles it can also be seen a 6

7 major drop on the first quartile but, on average, the reduction is also not significant due to the extreme temperatures (up to 2000 C) that the model is assuming for the exhaust gases (SCR operates up to 600 C). Figure 5 - Influence of LNT on NO x emission, for different driving context The results for LNT presented in Figure 5 show that the fast version accomplishes better performances, similarly for what was found for SCR. This technology reveals a big reduction in NO x emission for urban and mix cycles (-0,22 g/km and -0,25 g/km, respectively) for LNT fast. However, looking at the bar indicating the maximum value, it is noticeable that some of the urban cycles did not benefit from LNT influence due to the cycle s low temperature, which was below LNT s functioning temperature range ( C). Table 4 variation of fuel consumption due to the introduction of each technology (in %), for different driving contexts Urban Cycles Mix Cycles Extra-urban Cycles Stop/Start -14,6-3,5-0,4 20 kg -0,6-0,8-0,5 40 kg -1,2-1,5-1,1 Vehicle weight reduction 60 kg -1,9-2,3-1,7 80 kg -2,5-3,1-2,2 kg -3,2-3,8-2,8 C D reduction Tyres SCR LNT 0,290-0,1-0,7-1,7 0,285-0,2-1,0-2,5 Bigger dimension -0,1-0,5-0,1 Smaller dimension 0,4 0,3 0,2 Standard 0,7 0,0-0,8 Fast 0,7 0,0-0,8 Standard 0,7-0,1-0,8 Fast 0,8-0,1-0,8 From Tables 4 and 5 it is possible to observe the relative impact of each technology on fuel consumption and emissions. Tyre change does not have an expressive result, mainly because dimensions tested were very similar to the original one. Nevertheless it shows an interesting result, as it reveals a tendency for fuel consumption and NO x emission reduction with the increase of tyre radius, which affects the transmission (final drive). Stop/Start allows for fuel savings in urban driving of 14,6%, similar to the 12,2% found in [17]. For other driving contexts it not so effective, being considered insignificant in extra-urban driving. As for NO x, Stop/Start contribution to the emissions reduction is directly related with fuel consumption reduction, but its effect is highly dependent on the driving profile. 7

8 Table 5 variation of NO x due to the introduction of each technology (in %), for different driving contexts Urban Cycles Mix Cycles Extra-urban Cycles Stop/Start -6,1-3,7-0,2 20 kg -1,0-1,1-0,7 40 kg -2,0-2,2-2,0 Vehicle weight reduction 60 kg -3,0-3,3-2,0 80 kg -3,8-4,3-2,7 kg -4,7-5,3-3,4 CD reduction Tyres SCR LNT 0,290-0,2-1,0-2,0 0,285-0,4-1,5-3,2 Bigger dimension -0,1-0,2-0,4 Smaller dimension 0,1 0,4 0,5 Standard -4,9-49,5-14,4 Fast -9,4-57,5-19,2 Standard -8,0-15,3-3,7 Fast -28,2-31,2-5,9 Looking carefully to the relative variation that weight reduction introduces both in fuel consumption and NO x emission, it is possibly to observe a linear decreasing relation as the weight is reduced, as stated by [18]. Also, fuel savings of 1,7-2,3% to 2,8-3,8% for a weight reduction between 4,5% (60 kg) and 7,4% ( kg) were achieved, with comparable relative reductions on NO x emission. A C D of 0,285 corresponds to a reduction in 5% for this coefficient, which has accomplished 2,8% fuel savings and 3,2% less NO x emission in extra-urban cycles. Also for mix cycles it was attained 1% reduction in fuel consumption, supporting Fontaras and Samaras [18] results. SCR and LNT exhaust aftertreatment technologies provided the biggest impact on NO x reduction. For both technologies studied, the fast version has better performance (4,5-8% better for SCR and 2-20% better for LNT) and between the two solutions, SCR has a higher average NO x reduction across driving contexts. Nevertheless, LNT is better suited for urban applications than SCR, having 28,2% reduction versus only 9,4% reduction from SCR. Considering this analysis, the 3 most advantageous solutions (Stop/Start, SCR and kg weight reduction) were combined into one configuration, with the results presented on Figure 6 and Table 6. a) b) Figure 6 - Influence of technology combination on fuel consumption for different driving contexts 8

9 Table 6 variation of fuel consumption and NO x emission (in %) due to the technology combination, for different driving contexts Urban Cycles Mix Cycles Extra-urban Cycles Fuel consumption reduction (%) NO x emission reduction (%) The comparison of Table 6 with Tables 4 and 5 reveals that the fuel consumption variation is the sum of the reductions introduced by each individual technology, however for NO x in urban and mix cycles this is not the case. NO x emission variation in urban and mix cycles is less than the sum of the variation of the 3 solutions. Since this is not valid for extra-urban cycles, it was found that this phenomenon is related with the effect that Stop/Start system has on exhaust pipeline temperature, since it lowers the temperature by shutting the engine down. This temperature reduction affects SCR conversion efficiency. In order to overcome this situation, substituting SCR with LNT could be a solution, although it will certainly compromise the NO x reduction operation for extra-urban cycles but also for urban cycles with very low loads and exhaust temperatures, as they fall out the LNT s operating temperature range. Finally it is important to notice that none of the vehicle configurations is able to comply with the EURO 6 standard (for which the vehicle has been certified). The lowest value of NO x emission was obtained for the last configuration for mix cycles, ~ 0,33g/km, 4 times the limit (0,08 g/km). Since the cycles tested were from real-world driving, RDE should be considered with a conformity factor of 2.1 and so the limit would rise to 0,17g/km, still 2 times lower than the lowest emission average value registered. 4. CONCLUSIONS In order to reduce the adverse impact of road transportation on the environment, towards a more sustainable transportation sector, new regulatory measures are being introduced. Although the current measures and vehicle certification procedures have been considered unrepresentative of real-world operation, the new set of measures is aiming at a realistic evaluation. In order to cope with this new challenge and comply with the forthcoming limits, particularly NO x limits in the case of Diesel vehicles, several vehicle characteristics must be improved and new technology added. The objective of this study was to evaluate the potential of some low-cost technologies for fuel consumption and NO x emission reduction, in real-world driving, using a computational tool with experimental on-road data from a EURO 6 Diesel vehicle. The results show that change the tyre dimension by just a few millimeters introduces little variation, but reveals a trend of fuel consumption and emission reduction with the tyre s growing size. Stop/Start has a major influence on urban cycles, due to their high percentage of idling time, allowing for fuel savings of 14,6% which consequently lead to NO x emission reduction (6,1%). Although less relevant, it also has some impact in mix cycles with 3,5% fuel saving and NO x reduction of 3,7%. Drag coefficient reduction plays an important role in high speed cycles, such as extra-urban, where a 5% C D reduction leads to -2,5% fuel consumption and -3,2% NO x emission. A linear relation between vehicle s weight reduction and fuel consumption and emission reduction was observed. Also this solution produces similar effects in all driving contexts (~ -0,2 l fuel /km and ~ -0,03 to -0,05 g NOx /km), but only starts to have significant impacts over 40 kg. As for exhaust treatment technologies, SCR provides 2 to 3 times better overall results than LNT, however for urban cycles the latter has a significantly better performance (-28,2% NO x emission versus -9,4% from SCR). Based on individual values the three technologies with better average results (Stop/Start, SCR and kg weight reduction) were implemented together on the vehicle model and the results of this configuration show a sum of the individual benefits on fuel savings (4-17%), while on NO x reduction this was only observed for extra-urban cycles (23%). However, NO x emission variation in urban (14%) and mix (58%) cycles was less than the sum of the individual solutions, due to the reduced SCR conversion efficiency resulting from temperature drop in the exhaust line from Stop/Start operation. This shows the complexity of the interactions of the several technologies. 9

10 It was also found that the best vehicle configuration is not able to meet the current emission standards, having NO x values 4 to 10 times higher than EURO6. Even with RDE conformity factor, the lowest NO x emission value obtained for the best configuration in mix cycles (0,33 g/km), is still higher than the limit value of 0,17 g/km. Facing these results, there is the need to adequate the technological solutions to the context and for new strategies in order to comply with the incoming regulations. REFERENCES [1] IEA, Energy Balance - World Final Consumption, [Online]. Available: consumption. [Accessed: 01-Jan-2015]. [2] Twigg, M. V. Progress and future challenges in controlling automotive exhaust gas emissions, Appl. Catal. B Environ., vol. 70, no. 1 4, pp. 2 15, [3] European Environment Agency (EEA), Emissions of air pollutants from transport, Data and Maps, [Online]. Available: [Accessed: 10-Mar-2016]. [4] Thomas, M. Greenhouse gas and air pollutant emissions from EU transport, [5] Yang, L., Franco, V., Campestrini, A., German, J. and Mock, P. NOx control technologies for Euro 6 Diesel passenger cars: Market penetration and experimental performance assessment, [6] ICCT; DieselNet, EU: Light-duty: Emissions, [Online]. Available: transportpolicy.net/index.php?title=eu:_light-duty:_emissions. [Accessed: 05-Feb-2016]. [7] Mashadi B. and Crolla, D. Vehicle Powertrain Systems, First. John Wiley & Sons, Ltd, [8] Tietge, U., Mock, P., German, J., Bandivadekar, A., Ligterink, I. and Lambrecht, U. From laboratory to road: A 2015 update of official and real-world fuel consumption and CO2 values for passenger cars in Europe, [9] Weiss, M., Bonnel, P., Hummel, R., Manfredi, U., Colombo, R., Lanappe, G., Le Lijour, P. and Sculati, M. Analyzing on-road emissions of light-duty vehicles with Portable Emission Measurement Systems ( PEMS ), [10] Weiss, M., Bonnel, P., Hummel, R. and Steininger, N. A complementary emissions test for light-duty vehicles: Assessing the technical feasibility of candidate procedures, Publications Office of the European Union, Luxembourg, [11] Tietge, U., Mock, P., Zacharof, N. and Franco, V. Real-world fuel consumption of popular European passenger car models, [12] Mock, P., Kühlwein, J., Tietge, U., Franco, V., Bandivadekar, A. and German, J. The WLTP: How a new test procedure for cars will affect fuel consumption values in the EU, no. October, [13] European Commission, Vehicle emissions in real driving conditions_ Council gives green light to second package - Consilium, Press releases and statements, [Online]. Available: [Accessed: 18-Feb-2016]. [14] ICCT, The European real-driving emissions regulation, [15] Simmons, R., Shaver, G. M., Tyner, W. E. and Garimella, S. V. A benefit-cost assessment of new vehicle technologies and fuel economy in the U.S. market, Appl. Energy, vol. 157, pp. 1 13, [16] Bishop, J., Nedungadi, A., Ostrowski, G., Surampudi, B., Armiroli, P. and Taspinar, E. An Engine Start/Stop System for Improved Fuel Economy, [17] Fonseca, N., Casanova, J. and Valdés, M. Influence of the stop/start system on CO2 emissions of a diesel vehicle in urban traffic, Transp. Res. Part D Transp. Environ., vol. 16, no. 2, pp , [18] Fontaras G. and Samaras, Z. On the way to 130 g CO2/km-Estimating the future characteristics of the average European passenger car, Energy Policy, vol. 38, no. 4, pp , [19] Helms, H. and Lambrecht, U. The potential contribution of light-weighting to reduce transport energy consumption, Int. J. Life Cycle Assess., vol. 12, pp , [20] Schmidt, W.-P., Dahlqvist, E., Finkbeiner, M., Krinke, S., Lazzari, S., Oschmann, D., Pichon, S. and Thiel, C. Life cycle assessment of lightweight and end-of-life scenarios for generic compact class passenger vehicles, Int. J. Life Cycle Assess., vol. 9, no. 6, pp , [21] EPA, Cost and Effectiveness Estimates of Technologies Used to Reduce Light - duty Vehicle Carbon Dioxide Emissions, [22] Johnson, T. V. Review of diesel emissions and control, Int. J. Engine Res., vol. 10, no. 5, pp , [23] Mollenhauer, K. and Tschoeke, H. Handbook of Diesel Engines. Berlin, Heidelberg: Springer Berlin Heidelberg, [24] AVL Cruise, Cruise Product Description, Graz, [25] Nissan, All New Pulsar. [Online]. Available: [Accessed: 15-Mar-2016]. [26] Agudelo, A. F., García-Contreras, R., Agudelo, J. R. and Armas, O. Potential for exhaust gas energy recovery in a diesel passenger car under European driving cycle, Appl. Energy, vol. 174, pp , [27] Ghodke, P. R. and Suryawanshi, J. G. Optimisation of the 2.2 Liter High Speed Diesel Engine for Proposed Bharat Stage 5 Emission Norms in India, vol. 18, no. 1, pp , [28] Rolim, C. Impacts of adopting on board ICT and training on driving behavior, safety, energy and environment: application to light duty vehicles and buses, Instituto Superior Técnico, [29] Opel, New Opel Astra: Outstanding aerodynamics for best efficiency, [Online]. Available: [Accessed: 13-Apr-2016]. 10