Energy demand and emissions of a passenger vehicle fueled with CNG, gasohol, hydrous ethanol and wet ethanol based on the key points of the WLTC.

Interest in utilizing advanced lean-burn gasoline and diesel engines has increased in the last decades due to their reduced greenhouse gas emissions and increased fuel economy. One impediment to the increasing use of these engines, however, is the need to develop corresponding catalytic systems for controlling pollutant emissions. In particular, although still far from the fuel neutral United States (US) approach, European (EU) legislation limits for Nitrogen Oxides (NOx) emissions are becoming more and more severe and also type approval procedures are going to radically change with the introduction of Worldwide harmonized Light vehicles Test Cycle (WLTC) and Real Driving Emission (RDE) tests. Considering that test bench and chassis dyno experimental campaigns are costly and require a vast use of resources for the generation of data; therefore, reliable and computationally efficient simulation models are essential in order to identify the most promising technology mix to satisfy emission regulations and fully exploit advantages of diesel and lean-burn gasoline when minimizing the side effect of their emissions. Therefore, the aim of this work is to develop reliable models of the individual aftertreatment components and to calibrate the kinetic parameters based on experimental measurements which can be further used as a virtual test rig to evaluate the effectiveness of each technology in terms of reducing pollutant emissions. In the current work, a brief introduction regarding the passenger car emissions, regulations and control technologies, including in-cylinder control techniques and aftertreatment systems, is provided in Chapter 1. In addition, simulation modelling approaches for aftertreatment applications are discussed. More details about specific aftertreatment components are discussed in the next chapters. As an example, the modeling of a Selective Catalytic Reduction coated on Filter (SCR-F), on the basis of Synthetic Gas Bench (SGB) reactor data is presented in Chapter 2; focusing, in particular, on estimation of ammonia storage capacity, NOx conversion and soot reduction due to passive regeneration. LNT is analyzed in Chapter 3, focusing on the reactor-scale Synthetic Gas Bench (SGB) experiments and calibration of the 1D simulation model for two case studies with the aim to characterize Oxygen Storage Capacity (OSC), NOx Storage and Reduction (NSR) and light-off. The calibrated 1D simulation model is thereafter validated, in Chapter 4, for one of the case studies using engine-out emissions, mass flowrate and temperature traces over Worldwide harmonized Light vehicles Test Cycle (WLTC) as the boundary condition for the inlet of LNT for full-size component. Afterwards, the LNT model calibrated in Chapter 3 is, in Chapter 5, further reduced and linearized with reasonable assumptions to be used as a plant-model with very low computational requirement and in real time applications such as Electronic Control Unit (ECU)/ Hardware-in-the-Loop (HiL) systems. Finally, after discussing NOx control systems in previous chapters, modeling of Diesel Oxidation Catalyst (DOC), which plays a fundamental role not only for the CO and HC conversion, but also for promoting the oxidation of NO into NO2, is discussed in Chapter 6. It is worth noting that depending on the complexity of the kinetic model, different optimization tools are implemented for the calibration; as an example, Brent method is used for calibration of SCR-F kinetic model, likewise, Genetic Algorithm (GA) is used for the calibration of the DOC kinetic parameters; however, for more complex kinetic schemes like LNT both manual and automatic optimization is required to evaluate the most suitable reaction pathways and kinetic parameters. Accordingly, after development of the kinetic model for each aftertreatment component and validation of the full-scale model, further investigations could be devoted to combining the models in order to simulate the whole aftertreatment system and assess the performance over different driving cycles.

In this paper, the effects of biodiesel on performance and emission of the current and new-coming regulation cycles, namely the New European Driving Cycle (NEDC) and the Worldwide Harmonized Light Vehicles Test Cycle (WLTC), were investigated by conducting tests on a passenger car, a Euro-5 Ford Fiesta, equipped with a 1.5-L diesel engine. In a two-axle chassis dynamometer test bed, NEDC and WLTC were performed with pure diesel and biodiesel-to-diesel blend (30% biodiesel, 70% diesel in volume). A substantial reduction in CO (34%, 55%), HC (33%, 40%), and particulate number (PN) (22%, 31%) emissions was observed respectively for both the NEDC and WLTC when biodiesel was used. Besides, it was found that the WLTC has higher load and velocity profile compared to the NEDC. Moreover, lower CO, HC, and PN emissions were observed with B30 fuel under WLTC compared to the NEDC. Nevertheless, slightly higher CO2 and substantially higher NOx emissions were observed for the WLTC compared to the NEDC.

Increasing the use of renewable biofuels in internal-combustion-engine (ICE) vehicles is a key strategy for reducing greenhouse gas emissions and conserving fossil fuels. Hybrid vehicles used in urban environments significantly reduce fuel consumption compared to conventional internal-combustion-engine cars. In hybrid vehicles integrating electric propulsion with biofuels offers even more significant potential to lower fuel consumption. One would like to think they should also be less polluted in all cases, but some results show that the opposite is true. This study’s aim was to evaluate a hybrid vehicle’s energy and environmental performance using different gasoline–bioethanol blends. A Worldwide Harmonized Light Vehicles Test Cycle (WLTC) study was conducted on a Toyota Prius II hybrid vehicle to assess changes in energy and environmental performance. During the WLTC test, data were collected from the chassis dynamometer, exhaust gas analyser, fuel consumption meter, and engine control unit (ECU). The collected data were synchronised, and calculations were performed to determine the ICE cycle work, brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), pollutant emissions (CO, HC, and NOx), CO2 mass emissions per cycle, and brake specific pollutant emissions per kilometre. The study shows that the performance of the hybrid vehicle’s ICE is strongly influenced by the utilisation of electrical energy stored in the battery, especially at low and medium speeds. As the bioethanol concentration increases, the engine’s ECU advances the ignition timing based on the knock sensor signal. A comprehensive evaluation using the WLTC indicates that increasing the bioethanol concentration up to 70% improves the energy efficiency of the hybrid vehicle’s internal combustion engine and reduces pollutant and CO2 emissions.

<div class="section abstract"><div class="htmlview paragraph">Light commercial vehicles are an indispensable element for the transport of people and the delivery of goods, especially on extra-urban and long-distance routes. With a view to sustainable mobility, it is necessary to think about hybridizing these vehicles to reduce the fuel consumption as well as greenhouse gas emissions and particulate matter. These types of vehicles are generally powered by diesel and travel many kilometers a day. On the other hand, the use of light commercial vehicles in battery electric vehicle (BEV) configuration has already been started but is not receiving widespread recognition. In this panorama, starting from a study already developed for the hybridization of a plug-in light commercial vehicle in Worldwide harmonized Light vehicles Test Cycle (WLTC) condition, the simulation analysis has been extended to the plug-in hybrid vehicle (PHEV) operating in real driving emission conditions (RDE). In particular, using Advisor software, a vehicle has been simulated in different plug-in hybrid configurations. The software has been validated with real operation data of a euro 6 diesel engine. The general hypothesis underlying the research consists in the possibility of using these vehicles in totally electric mode in the city and in hybrid mode outside urban centers; with the aim of reducing polluting emissions in populated city but completing the delivery mission during all phases of vehicle operation. The PHEV simulations have been performed on both WLTC and RDE condition. In the latter mode, particular attention has been devoted to the interpretation of data from GPS sensor: like the slope of the route or the presence of tunnels. The success of the simulation depends on a correct and careful reconstruction of the GPS data. Three vehicles with different hybridization factors have been simulated: 0.44, 0.56, and 0.67, respectively, with power equal to that of the base vehicle. The battery packs have been sized for the three hybrid vehicles and simulations were carried out in both Charge Depleting and Charge Sustaining configuration. In charge depleting for the highest hybrid configuration (HF=0.66), the results demonstrate that a reduction of up to 80% and 76% in fuel can be saved While a reduction up to 75% and 45% in NOx emissions can be achieved on WLTC and RDE cycle, respectively. On the other hand, when the battery is discharged, for HF=0.67, although consumption can be reduced by up to 45%, NOx emissions also increase by 183% even if ICE operation mode has to be better optimize for hybrid operation. Finally, even if the hybrid solutions is really convenient if compared to the conventional vehicle in terms of fuel savings and NOx pollutant emissions, about a realistic estimation of the CO2 reduction that can be achieved the use of electrical energy must be take into account.</div></div>

Engine and exhaust control technologies applied to compressed natural gas (CNG) transit buses have advanced from lean-burn, to lean-burn with oxidation catalyst (OxC), to stoichiometric combustion with three-way catalyst (TWC). With this technology advancement, regulated gaseous and particulate matter emissions have been significantly reduced. Two CNG transit buses equipped with stoichiometric combustion engines and TWCs were tested on a chassis dynamometer, and their emissions were measured. Emissions from the stoichiometric engines with TWCs were then compared to the emissions from lean-burn CNG transit buses tested in previous studies. Stoichiometric combustion with TWC was effective in reducing emissions of oxides of nitrogen (NOX), particulate matter (PM), and nonmethane hydrocarbon (NMHC) by 87% to 98% depending on pollutants and test cycles, compared to lean combustion. The high removal efficiencies exceeded the emission reduction required from the certification standards, especially for NOX and PM. While the certification standards require 95% and 90% reductions for NOX and PM, respectively, from the engine model years 1998–2003 to the engine model year 2007, the measured NOX and PM emissions show 96% and 95% reductions, respectively, from the lean-burn engines to the stoichiometric engines with TWC over the transient Urban Dynamometer Driving Schedule (UDDS) cycle. One drawback of stoichiometric combustion with TWC is that this technology produces higher carbon monoxide (CO) emissions than lean combustion. In regard to controlling CO emissions, lean combustion with OxC is more effective than stoichiometric combustion. Stoichiometric combustion with TWC produced higher greenhouse gas (GHG) emissions including carbon dioxide (CO2) and methane (CH4) than lean combustion during the UDDS cycle, but lower GHG emissions during the steady-state cruise cycle. Implications: Stoichiometric combustion with three-way catalyst is currently the best emission control technology available for compressed natural gas (CNG) transit buses to meet the stringent U.S. Environmental Protection Agency (EPA) 2010 heavy-duty engine NOX emissions standard. For existing lean-burn CNG transit buses in the fleet, oxidation catalyst would be the most effective retrofit technology for the control of NMHC and CO emissions.

Fuel consumption and emission performance from light-duty conventional/hybrid-electric vehicles over different cycles and real driving tests

The article considers the issues of non-repeatability of exhaust emission and fuel consumption test results for road vehicles tested on a chassis dynamometer. Empirical results of passenger car tests on a chassis dynamometer in the WLTC (Worldwide Harmonized Light Vehicles Test Cycle) test were used. Tests were conducted in four repeated sets to assess the repeatability of the test results. The road emission of hydrocarbons, non-methane hydrocarbons, carbon monoxide, nitrogen oxides, particulate matter and carbon dioxide, the road number of particulate matter and operational fuel consumption were determined. The coefficient of variation of the values measured in the four tests was determined, taken as a measure of the repeatability of the test results. The coefficient of variation of the road emission of carbon dioxide and operational fuel consumption is the lowest. No significant differences were found in the values of the measured exhaust emission.

The paper presents results of considerations on the repeatability of the passenger car test results obtained in the WLTP procedure on a chassis dynamometer. The research concerned the aspects of exhaust emissions and fuel consumption. Measurements were carried out in the WLTC test with a cold engine start and then in four WLTC (Worldwide harmonized Light vehicles Test Cycle) tests with a hot engine start. The following values were measured: average specific distance emissions of hydrocarbons, non-methane hydrocarbons, carbon monoxide, nitrogen oxides, particulate matter and carbon dioxide, specific distance particulate number, and operational fuel consumption. Thus, it was possible to assess the impact of the engine's thermal state at start-up on the test results and the nature of test results repeatability with the start-up of a hot engine. The repeatability of the test results was assessed based on the coefficient of variation obtained in the individual tests and the relationship of the maximum difference between measurement results values in the individual tests for a hot engine start. The obtained test results turned out to be very diverse for the considered parameters and indicated low repeatability. Values of carbon dioxide emissions and operational fuel consumption were definitely the least varied in individual hot engine start tests. The exhaust emission of particulate matter varied the most in individual test iterations. However, the specific distance particulate number was relatively similar between individual tests, less so than the exhaust emission of other pollutants. In the case of different engine thermal state at start-up, the emitted particulate number varied the most in the test results, while the emission of carbon dioxide and operational fuel consumption varied the least. The repeatability of executing the velocity process in WLTC tests at hot engine and cold engine start-up was also examined as processes determining exhaust emissions and fuel consumption. These tests were much more repeatable than the exhaust emission and fuel consumption.

The performance analysis of electric vehicles (EVs) under varying drive cycles is crucial for optimizing energy efficiency and range. This research focuses on evaluating EV performance by simulating and analyzing behavior across diverse driving conditions, represented by standardized drive cycles. These cycles, such as the Worldwide Harmonized Light Vehicles Test Cycle (WLTC) and urban driving cycles, replicate real-world driving patterns, including acceleration, deceleration, and speed variations. The study investigates key performance indicators, including energy consumption, battery state of charge, and motor efficiency, under each drive cycle. By comparing these metrics, the impact of different driving styles and environments on EV performance is assessed. This analysis provides valuable insights for improving EV design, battery management systems, and energy optimization strategies. Ultimately, this research aims to enhance the overall efficiency and practicality of EVs for widespread adoption. Key Words : Electric vehicle (EV); Drive Cycle Performance Analysis ;Energy Consumption ; Battery State of Charge (SOC) ; Motor Efficiency; Optimization, Range; WLTC (Worldwide Harmonized Light Vehicles Test Cycle)

Vehicular emissions of soot vary with the driving conditions and fuel properties. In 2017, China’s central government released a policy to promote ethanol blended gasoline fuels, and this policy will be rolled out nationwide in 2020. It is necessary to characterize the emission differences between traditional vehicular fuels used in China and ethanol blended fuels. In this study, black carbon (BC) emissions from three gasoline light-duty passenger vehicles (LDPVs) were measured using the New European Driving Cycle (NEDC) and the Worldwide harmonized Light vehicles Test Cycle (WLTC) . This study utilized three fuels, namely, two E10 fuels and a traditional gasoline (E0). The experimental results showed that the use of E10 blends (gasoline containing 10% ethanol) reduced BC emissions by 7–38%. Based on phase-separated analysis, BC emissions in the initial driving phase and the high-speed phase (e.g., the 1st ECE-15 phase in the NEDC and the extra-high speed phase in the WLTC) represented the majority (86–96%) of the total BC emissions, and the emission factors during the 1st ECE-15 phase (NEDC) and the low-speed phase (WLTC) were 0.36 mg km–1 and 0.37 mg km–1 lower, respectively, for the ethanol-blended fuels than the ethanol-free fuel. Furthermore, we found that using ethanol-blended fuels could reduce the mass concentration of the BC emitted during cold starts, which lasted 53–95 s for the tested vehicles, by 4.28 ± 4.19 mg km–1 and 2.06 ± 0.17 mg km–1 in the NEDC and the WLTC, respectively.

The idle start-go (ISG) system has been widely used, but there have been few relevant studies of its effect on emissions. This paper investigates fuel economy, total hydrocarbon (THC), carbon monoxide (CO), nitrogen oxides (NOx), particulate mass (PM), and particle number (PN) emissions from China VI gasoline direct injection (GDI) vehicles with and without ISG. Three test cycles were performed under hot start conditions, that is, the worldwide harmonized light vehicle test cycle (WLTC), the China light-duty vehicle test cycle (CLTC), and the USA federal test procedure-75 (FTP-75). About 28 idling phases were selected to specifically analyze the influence of ISG system. The results reveal that ISG system helps decrease fuel consumption, THC and CO emissions but aggravates NOx and solid PN emissions. Also, ISG system increases the proportions of sub-23 nm and nucleation-mode particle emission. Idling time plays a role in fuel economy, THC and CO emissions, while accelerated speed affects the emissions of THC, CO, NOx, and PN.

Pollutant emissions and diesel oxidation catalyst performance at low ambient temperatures in transient load conditions

Selective catalytic reduction filter (SDPF) technology constitutes a critical methodology for controlling nitrogen oxide (NOx) and particulate matter emissions from light-duty diesel vehicles. A series of SDPFs with different sulfur poisoning times and concentrations were prepared using the worldwide harmonized light vehicles test cycle (WLTC). Bench testing revealed that sulfur poisoning diminished the catalyst’s NH3 storage capacity, impaired the transient NOx reduction efficiency, and induced premature ammonia leakage. After multiple sulfur poisoning incidents, the NOx reduction performance stabilized. Higher SO2 concentrations accelerated catalyst deactivation and hastened the attainment of this equilibrium state. The characterization results for the catalyst indicate that the catalyst accumulated the same sulfur content after tail gas poisoning with different sulfur concentrations and that sulfur existed in the form of SO42−. The sulfur species in low-sulfur-poisoning-concentration catalysts mainly included sulfur ammonia and sulfur copper species, while high-sulfur-poisoning-concentration catalysts contained a higher proportion of sulfur copper species. Neither species type significantly altered the zeolite coating’s crystalline structure. Sulfur ammonia species could easily lead to a significant decrease in the specific surface area of the catalyst, which could be decomposed at 500 °C to achieve NOx reduction performance regeneration. In contrast, sulfur copper species required higher decomposition temperatures (600 °C), achieving only partial regeneration.

<div class="htmlview paragraph">Exhaust emissions of three vehicles fueled with compressed natural gas (CNG) were compared with emissions of three counterpart gasoline vehicles. The natural gas vehicles were tested on four CNG fuels covering a wide range of pipeline natural gas compositions. The gasoline vehicles were tested on AQIRP Industry Average gasoline and a reformulated gasoline meeting California 1996 regulatory requirements.</div> <div class="htmlview paragraph">Nonmethane hydrocarbon (NMHC) and toxic air pollutant emissions of the CNG vehicles were about one-tenth those of their counterpart gasoline vehicles, while methane emissions were about ten times those of the gasoline vehicles. Carbon monoxide (CO) and nitrogen oxides (NO<sub>x</sub>) emissions were more variable among the three vehicle pairs. CO emissions ranged from 20 to 80% lower with CNG than with gasoline, and NO<sub>x</sub> ranged from 80% lower with CNG to equivalent to gasoline.</div> <div class="htmlview paragraph">Comparing the four CNG fuels, methane increased about 40%, NMHC decreased about 40%, and reactivity-weighted emissions decreased about 15% when CNG fuel methane content increased from 91 to 98% of fuel hydrocarbons (86 to 97% of total gas composition). There were no statistically significant effects on CO, NO<sub>x</sub> or toxic air pollutants.</div> <div class="htmlview paragraph">Fuel economy expressed as miles per million BTUs was about 20% lower for the CNG vehicles than for their gasoline counterparts. Reactivity-weighted emissions (RWE), calculated to estimate differences in potential ozone forming characteristics of emissions, were about 90% lower for the three CNG vehicles than for their gasoline counterparts when the calculation was based on NMHC emissions alone, and about 80% lower when exhaust methane and CO were included. The fuel effects on RWE parallel the effects on NMHC mass.</div> <div class="htmlview paragraph">Reformulated test gasoline C<sub>2</sub> representing California Phase 2 gasoline, tested in the gasoline vehicles, had consistently lower NMHC, CO, and NO<sub>x</sub> and toxics emissions than AQIRP Industry Average gasoline. The average decreases in the three emissions were 24%, 21%, 12% and 36%, respectively. These results are consistent with other AQIRP data for these fuels.</div>

Experimental investigations carried out on a single-cylinder four-stroke motorcycle spark ignition engine operating on gasoline and natural gas are reported in the present paper when compressed natural gas (CNG) and hydrogen were used as fuel. The investigations were carried out by mixing a small percentage of hydrogen (5 to 30%) with CNG and supplied to the engine. Hydrogen and CNG were mixed in a developed mixer and supplied through the inlet manifold system. Performance and emission tests carried on the engine with this system showed a considerable improvement in power output and in thermal efficiency as well as reduction in brake specific energy consumption (BSEC), hydrocarbon (HC) and carbon monoxide (CO) emissions. Power loss associated with CNG utilization had improved with the addition of hydrogen fuel (20-30%) was observed. The combustion analysis was carried out for different rates of hydrogen addition. The rapid rate of burning of CNG-air mixture with the addition of hydrogen showed higher energy release rate, leading to higher cylinder pressures. Hydrogen blended with CNG enabled leaner operation and showed an improvement in BMEP and environmental benefit. Key words: Hydrogen, CNG, CO emissions, spark engine, fuel mixer