PN Emissions Research Articles

Particle number emissions from fully warmed gasoline vehicles at various ambient temperatures

Road vehicles have become the primary source of fine particles in many large cities. Vehicle hot-start PN emissions at various ambient temperatures were studied previously. Still, these studies used the same rolling resistance setting at different ambient temperatures and the tests at various ambient temperatures have similar PN emissions. Vehicles get larger resistance at cold ambient temperatures, so this experimental setting (same resistance at various ambient temperatures) is beyond the natural conditions. To evaluate how ambient temperatures affect the PN emissions from fully warmed vehicles, two vehicles were tested at four ambient temperatures: −10 °C, 0 °C, 23 °C, and 40 °C. Vehicle resistance variations under different ambient temperatures were taken into consideration. The observed results proved that PN emission would significantly deteriorate under cold conditions even when the vehicles are thoroughly warmed. The PN emission factor at −10 °C could be six times higher than at 23 °C. The deteriorated PN emission is caused by enhanced fuel enrichment and GPF regeneration, and larger vehicle resistance under cold ambient temperatures is the underlying reason for the increased PN emission. For the first time, this study proved that PN emission from fully warmed vehicles would significantly deteriorate when the ambient temperature decreases. The results could be used for emission models, inventory, and regulations.

Investigation on combustion and emission characteristics of a CRDI engine fueled with diesel cyclopentanol blends and verification through on-road real-time test

In this study, the combustion and emission characteristics of a diesel engine fueled with diesel cyclopentanol blends were experimentally studied through the engine bench test and real-time vehicle test. The results indicated that the cyclopentanol addition weakened the premixed combustion process and accelerated the diffusion combustion process, resulting in an increased peak cylinder pressure and peak combustion temperature. In addition, with the increase of cyclopentanol addition, the ignition delay prolonged, the combustion duration shortened and the heat released more concentratedly. The addition of cyclopentanol decreased both the PM number and volume concentrations significantly, while increased the NOx emission due to the increased peak combustion temperature. At 2000 r/min, CP10 had little effect on inhibiting the nucleation ultrafine particles (≤ 50 nm). Urban, rural and highway roads were considered for on-road real-time vehicle test. The results were consistent with the engine bench test. For urban, rural, and highway areas, the average PN emissions of CP20 were 4.948 × 106, 4.707 × 106, and 3.314 × 106 per cm3, respectively, while those for diesel were 5.755 × 106, 5.547 × 106, and 4.058 × 106 per cm3, respectively.

Effects of Polyoxymethylene Dimethyl Ethers Addition in Diesel on Real Driving Emission and Fuel Consumption Characteristics of a CHINA VI Heavy-Duty Vehicle

Polyoxymethylene dimethyl ethers (PODE), as the most potential oxygenated alternative fuel for diesel engines, is widely investigated. Considering the importance of research on real driving emissions (RDE) and the few studies focus on the emission characteristics of the PODE/diesel blended fuels under real driving conditions, a portable emission measurement system (PEMS) was applied to measure the RDE of a heavy-duty tractor fueled with diesel or PODE/diesel blends. The tests were carried out in accordance with the relevant regulations of the CHINA VI emission standards. The second-by-second data from PEMS and the OBD system were utilized to construct engine transient operating maps. The results indicated that the addition of PODE can still decrease CO and PN emissions significantly under real driving conditions, although the low load conditions are still the areas of high brake specific CO and brake specific PN emissions. The NOx emissions, however, were not reduced as the results of the steady-state experiment of the same model of the engine. Fuel mass consumption raised when PODE was added, while the overall brake thermal efficiency improved, especially for the blending ratio of 30%, up to 40.3%, which is higher than 38.4% of pure diesel operation.

An Analysis of Emissions from An Ethanol Flex-Fuel Vehicle under Two Distinct Driving Cycle Tests during Cold Start

Ethanol flex-fuel vehicles are introduced to Thailand’s market and believed that they provide an alternative way in terms of reducing crude oil and octane booster import. Many literatures suggested that they also helped to reduce some emission species including the greenhouse gas. However, sufficient proof of this flex-fuel vehicle comparing the conventional versus realistic driving cycle tests during cold starts is not clearly identified. This research focuses on the comparison of performance, fuel consumption, and emissions of a flex-fuel vehicle using Gasohol E10, E50, and E85 tested under the New European Driving Cycle (NEDC) and Bangkok Driving Cycle (BDC). Tests were done on a Chassis Dynamometer in the Automotive Emission Laboratory of the Pollution Control Department. Considering emission data from both test cycles, the more ethanol ratios in gasoline, the more CO, NMHC, NOx, CO2 and PN emissions reductions. On the contrary, HC emissions are increased but still under EURO4 standards. Fuel consumptions on E85 are increased around 30% compared to E10 for both test cycles. However, the pattern of driving cycles significantly impacts the amounts of CO/NOx emissions and fuel consumption. During cold start periods, regardless of percentages of ethanol blends, the amounts of HC and CO emissions for both test cycles are similar due to running engine in rich conditions by ECU management to warm three-way catalyst. On the contrary, NOx emissions are strongly related to frequent acceleration and deceleration sequences of the tested driving cycle.

Impact of driving style and traffic condition on emissions and fuel consumption during real-world transient operation

This study investigated the impact of driving style and traffic condition on emissions and fuel consumption using a selected range of real-world transient drive cycles, using both diesel and a diesel–biodiesel blend on a turbocharged diesel engine. Using 30 drivers, real-world measurements were performed with a Hyundai iLoad 2017 automatic diesel van in a typical urban driving route in Brisbane. From the on-road measurements, six different transient cycles were developed based on different driving styles (timid, normal and aggressive) and traffic conditions (off-peak and peak hour) according to the guidelines presented in the US Code of Federal Regulations, Title 40, Part 86. In this paper, engine operating parameters (engine speed and load), gaseous emissions (NOx, CO and CO2), particulate matter emissions (PM and PN), and fuel consumption were investigated in relation to driving style, traffic condition and fuel type, using different data analysis methods such as Kernel density estimation (KDE) and Analysis of variance (ANOVA). The investigation revealed that engine behaviour during real-world transient operation is entirely different from the steady-state operation, which results in significantly high emissions. Driving style has a strong influence on emissions, evident from emission results as well as ANOVA analysis. Aggressive driving generates a higher number of transient micro-trips which ultimately results in an overshoot in emissions. A moderate increment in CO2 and NOx emissions (up to 37% and 38% respectively) and a high increment in CO emission (up to 88%) was observed for the aggressive cycles. PM and PN emission increased significantly (up to 112% and 538% respectively) for aggressive cycles. Biodiesel showed a promising impact in PM and PN emission reduction (up to 71% PM and 68% PN respectively) regardless of the driving style and traffic condition. In general, off-peak cycles demonstrated more severe results for real-world transient emission generation because of comparatively higher sharp acceleration and turbocharger lag events. Fuel consumption is dominated by traffic conditions where peak hour cycles increased the brake-specific fuel consumption.

Study on the Emission Characteristics of Urban Buses at Different Emission Standards Fueled with Biodiesel Blends.

Biodiesel is a promising clean and alternative fuel that can meet the demand of energy saving and environmental protection. In this study, the effects of biodiesel blends on the gaseous and particulate emission characteristics of China-III, IV, and V urban buses were investigated based on a heavy chassis dynamometer. The results showed that the biodiesel blend resulted in a reduction in CO, THC, PN, and PM emission but an increase in the NOx and CO2 emission, and the effects were enhanced with the biodiesel ratio, which also depended on the bus speed. Simultaneously, the emission standards of buses had an obvious effect on the emissions and changed the effect of biodiesel on the emissions. A higher emission standard of the bus highlighted the effect of biodiesel on the emission. From China-III to China-IV to China-V buses, the comprehensive changes produced by B5 in the emissions increased from 5.57 to 6.78 to 6.83%, while for B10, a significant increase in the changes was obtained, reaching 12.98, 14.68, and 15.02%, respectively, for the three emission stage buses.

Study on pollutant emission characteristics of different types of diesel vehicles during actual road cold start

The current regulations of heavy-duty vehicles in China do not include the emissions in the cold start stage into the overall emission evaluation. However, the speed of heavy-duty diesel vehicles in the cold start stage is often low and the proportion of idle-conditions is large, resulting in the difference between the actual test results and evaluation results of emissions. Therefore, in order to accurately evaluate the impact of emission during cold start on the overall emission, in this study, the OBS-ONE portable vehicle emission test equipment was used to test the emission of three representative heavy-duty diesel vehicles with different types under actual road driving conditions, and the cumulative averaging (CA) method was adopted to calculate and analyze the test emission data.Firstly, the cold start emission of different types of heavy-duty vehicles was evaluated. The results show that the contribution rate of pollutant emission in the cold start stage is high, in which NOx emission accounts for 40–90% of the whole trip. It was unreasonable for regulations to exclude data in the cold start stage. The cold start duration of vehicle A is nearly 300 s longer than that of vehicle C, however, the NOx and PN emission factors of vehicle A are nearly 10 times and 100 times smaller than that of vehicle C at the cold start stage respectively. The cold start duration, fuel consumption and the emission factors in cold start stage of different types of heavy-duty diesel vehicles do not have a unified law. Secondly, the emission characteristics and differences of different types of heavy-duty vehicles are studied at the instantaneous level, and the internal mechanism causing the emission differences is explored and revealed. In the cold stage, CO2 emission shows a good correlation with the fuel consumption. CO, NOx emissions show a good correlation with the fuel consumption when the engine and post-treatment temperature are low, and CO and NOx emissions decrease with the increase of engine and post-treatment temperature. PN emissions are mainly related to the engine working state. Finally, the influence of dynamic parameters v·a and RPA on pollutant emission was analyzed. The results show that driving force is an important factor affecting CO2 emission, and RPA has no obvious correlation with emission at cold start stage.

Detailed characterization of particle emissions from battery fires

Lithium-ion (Li-ion) batteries that are becoming ubiquitous in various applications may be susceptible to thermal runaway when subjected to certain abuse factors. Fire ensuing from such a thermal runaway event results in significant release of gaseous and particle emissions that pose a critical safety risk to human health. This program was focused on performing detailed characterization of particle emissions from Li-ion battery systems that experience thermal runaway. Four identical lithium iron phosphate (LFP) modules and one nickel manganese cobalt oxide (NMC) module were each subjected to thermal runaway. Two LFP modules and the NMC module were triggered into runaway via nail-penetration, while the remaining two LFP modules were triggered into runaway via over-charging. Particle emissions were characterized in terms of particulate matter mass (PM2.5), real-time total (solid + volatile) and solid PN/size (5.6–560 nm), real-time black carbon, organic/elemental carbon partitioning and volatile fraction of PM2.5. Gaseous emissions were measured using a real-time Fourier Transform Infrared spectrometer. Results suggest that battery fires can result in significant particle and gaseous emissions that may be a function of initiation mechanism, battery chemistry, and cell arrangement within a module among other variables. LFP modules subjected to nail penetration yielded relatively less emissions as propagation was not observed. Over-charging LFP modules resulted in significant emissions that showed a continuous increase till peak levels were reached followed by a gradual decrease. PM2.5 emissions ∼380 g/h and total PN emissions ∼1.5E + 17 particles/h (or 1.3E07 part./cm3) were observed. Nail-penetration of the NMC module resulted in several distinct peaks due to propagation of runaway from cell-to-cell. This module resulted in the highest emission rates of 551 g/h of PM2.5 and 2.1E + 17 particles/h (or 1.9E07 part./cm3) of total PN.Copyright © 2022 American Association for Aerosol Research

Effects of lubricant-fuel mixing on particle emissions in a single cylinder direct injection spark ignition engine

Gasoline direct injection (GDI) engines emit less carbon dioxide (CO2) than port fuel injection (PFI) engines when fossil fuel conditions are the same. However, GDI engines emit more ultrafine particulate matter, which can have negative health effects, leading to particulate emission regulations. To satisfy these regulations, various studies have been done to reduce particulate matter, and several studies focused on lubricants. This study focuses on the influence of lubricant on the formation of particulate matter and its effect on particulate emissions in GDI engines. An instrumented, combustion and optical singe-cylinder GDI engine fueled by four different lubricant-gasoline blends was used with various injection conditions. Combustion experiments were used to determine combustion characteristics, and gaseous emissions indicated that the lubricant did not influence mixture homogeneity but had an impact on unburned fuels. Optical experiments showed that the lubricant did not influence spray but did influence wall film formation during the injection period, which is a major factor affecting particulate matter generation. Particulate emissions indicated that lubricant included in the wall film significantly affected PN emissions depending on injection conditions. Additionally, the wall film influenced by the lubricant affected the overall particle size and its distribution.

Plateau PEMS emission characteristics analysis of heavy-duty diesel vehicles with different technical routes

Real driving emission characteristics of heavy-duty diesel vehicles with different technical routes were conducted by portable emission measurement system (PEMS) tests at different altitudes of 1400 meter and 2300 meter. Results show that the use of EGR will lead to increased particulate matter emissions but has little effect of NOx emissions. The EGR application exhibits a large effect on the PN emission but a little effect on NOx emission. PN emissions were strongly correlated with engine load during the PEMS test. The higher the engine load, the higher the PN emissions even at lower altitudes. There are large differences in PEMS test results even at the same altitude.

Research on RDE performance for in-use vehicles especially at high altitude conditions in China

The real driving emissions (RDE) of an in-use gasoline an in use diesel light-duty (LD) vehicle , both are SUV type, are studied based on portable emission measurement system (PEMS). The gasoline vehicle complying with emission standard of China 6 with a mileage of about 50000 km, and the diesel vehicle in this study is complying with emission standard of China 5 with a mileage of about 130000 km for there are hardly any China 6 diesel vehicles in-use in major city. Special attentions are paid on their emission behaviors at high altitude conditions (1300 to 3000 m above sea level). It is observed that the RDE test approach is still feasible for revealing in-use real driving emissions at extremely high altitudes (>1300 m, which is beyond the upper limit of extended altitude conditions according to the Euro 6 regulation). The results reveals that for in-use China 6 gasoline vehicle, the efficient three way catalyst (TWC) is capable of handling NOx, CO emission sufficiently, accompany with port fuel injection that guarantees the RDE test results (NOx, PN, CO) fulfill the China 6 emissions standards (which are 35 mg/km, 6E11 #/km and 500 mg/km respectively). And for China 5 in-use diesel vehicle, EGR as the only NOx control means is not sufficient which brings extremely high real driving NOx emission, with the maximum value exceeds about 3.7 and 23.2 times of the China 5 and China 6 NOx emission limits, but on the other hand, the PN emission is only about 1% of the China 6 PN standard value for the usage of DPF.

Pollutant emission and CO2 emission at various vehicle loading for a heavy-duty commercial vehicle by EIL methodology

Pollutants and carbon dioxide (CO2) under different vehicle loading were investigated on a dump truck with a maximum designed total mass of 18000 kg. An engine-in-the-loop (EIL) methodology was applied to achieve the test consistency because EIL can use the same road, driver and vehicle model. The results show that the total CO2 emission increases while the brake specific CO2 emission decrease as the vehicle loading increases. Both the total and specific emissions of PN increase when vehicle loading increases. The effect regularity of increasing vehicle loading on NOx, THC and CO is not significant. It is necessary to comprehensively consider the changes in the raw exhaust due to the engine operation points changes and in the SCR catalytic efficiency derived from the SCR inlet temperature variation. The DPF generation is also need to be concerned because the CO2, PN and NOx emissions will rapidly increase during this period.

Influence of driving conditions on the emission characteristics of China VI heavy-duty vehicles

In order to study the feasibility of the low load cycle (LLC) condition applied to China’s heavy-duty trucks, this paper selects a China Ⅵ heavy-duty trucks with 100% load to study the pollutant emission and driving condition characteristics of LLC, C-WTVC and CHTC-HT on chassis dynamometer. Vehicle specific power (VSP) is adopted as analysis method. The results show that the emission of pollutants (NOX, PN, CO2) under LLC cycle is higher than that under C-WTVC and CHTC-HT. the NOx emission and PN emission of the LLC are about 1 order of magnitude and 3 orders of magnitude higher than those under C-WTVC and CHTC-HT respectively. Compared with C-WTVC and CHTC-HT, CO2 emission of the LLC has the highest total emission performance, while the average emission rate of each VSP interval has the lowest performance, about 3.7g/s.

Study on combustion and emissions of a hydrous ethanol/gasoline dual fuel engine with combined injection

Hydrous ethanol has lower cost and energy consumption during the production process than anhydrous ethanol. Many researchers used hydrous ethanol instead of anhydrous ethanol to manufacture hydrous ethanol-gasoline. The water ratio in hydrous ethanol (ω) determines the energy consumption in the production process of ethanol. However, no one researched the effects of different ω on combustion and emissions of hydrous ethanol-gasoline. So, we prepared five kinds of ethanol with different ω (0, 5%, 10%, 15%, 20% vol.) to research the effects of ω on combustion and emissions. This study adopted combined injection with hydrous ethanol direct injection plus gasoline port injection (HEDI + GPI). The engine speed was 1500 rpm, and λ was 1, the intake manifold absolute pressure was 48 kPa, the direct injection ratio was 20%, five spark timings varied from 5 °CA BTDC to 25 °CA BTDC. The results showed hydrous ethanol prolonged flame development and propagation duration, decreased Tmax and Pmax, delayed APmax. Water increased COVimep, but using hydrous ethanol at the reasonable spark timing would not significantly affect the stability. Meanwhile, when the spark timing was MBT, compared with GE (gasoline/anhydrous ethanol dual fuel) fuel, as ω in GEW (gasoline/hydrous ethanol dual fuel) fuels increased, torque and brake thermal efficiency improved by 1.69%, 1.13%, −0.01%, −0.77%; HC increased by 2.13%, 9.02%, 23.89%, 37.15%; CO decreased by 41.95%, 28.56%, 5.59%, 2.46%; NOx decreased by 10.10%, −0.75%, −0.17%, 4.18%; total PN emissions decreased by 24.07%, 69.57%, 36.34%, 32.45%. Meanwhile, more water caused the size of particles to drop, made particles smaller.

The Effect of Pure Oxygenated Biofuels on Efficiency and Emissions in a Gasoline Optimised DISI Engine

The negative impact of transport on climate has led to incentives to increase the amount of renewable fuels used in internal combustion engines (ICEs). Oxygenated, liquid biofuels are promising alternatives, as they exhibit similar combustion behaviour to gasoline. In this article, the effect of the different biofuels on engine efficiency, combustion propagation and emissions of a gasoline-optimised direct injected spark ignited (DISI) engine were evaluated through engine experiments. The experiments were performed without any engine hardware modifications. The investigated fuels are gasoline, four alcohols (methanol, ethanol, n-butanol and iso-butanol) and one ether (MTBE). All fuels were tested at two speed sweeps at low and mid load conditions, and a spark timing sweep at low load conditions. The oxygenated biofuels exhibit increased efficiencies, even at non-knock-limited conditions. At lower loads, the oxygenated fuels decrease CO, HC and NOx emissions. However, at mid load conditions, decreased volatility of the alcohols leads to increased emissions due to fuel impingement effects. Methanol exhibited the highest efficiencies and significantly increased burn rates compared to the other fuels. Gasoline exhibited the lowest level of PN and PM emissions. N-butanol and iso-butanol show significantly increased levels of particle emissions compared to the other fuels.

Modelling liquid film in modern GDI engines and the impact on particulate matter emissions – Part 1

This paper presents the details of a Computational Fluid Dynamics methodology to accurately model the process of mixture preparation in modern Gasoline Direct Injection engines, with particular emphasis on liquid film as one of the main causes of Particulate Matter formation. The proposed modelling protocol, centred on the Bai-Onera approach of droplets-wall interaction and on multi-component surrogate fuel blend models, is validated against relevant published data and then applied to a modern small-capacity GDI engine, featuring centrally-mounted spray-guided injection system. The work covers a range of part-load, stoichiometric and theoretically-homogeneous operating conditions, for which experimental engine data and engine-out Particle Number measurements were available. The results, based on the parametric variation of start of injection timing and injection pressure, demonstrate how both fuel mal-distribution and liquid film retained at spark timing, may contribute to PN emissions, whilst their relative importance vary depending on operating conditions and engine control strategy. Control of PN emissions and compliance with future, more stringent regulations remain large challenges for the engine industry. Renewed and disruptive approaches, which also consider the sustainability of the sector, appear to be essential. This work, developed using Siemens Simcenter CFD software as part of the Ford-led APC6 DYNAMO project, aims to contribute to the development of a reliable and cost-effective digital toolset, which supports engine development and diagnostics through a more fundamental assessment of engine operation and emissions formation.

Effect of engine control parameters on combustion and particle number emission characteristics from a SIDI engine fueled with gasoline-ethanol blends

In this study, the impact of engine control parameters on combustion behaviors and particle number emissions was investigated with a spark ignition direct injection (SIDI) engine used various gasoline-ethanol blended fuels. The SIDI engine was tested with the E0, E30 and E85 at a engine operation of 1500 rpm/1.5 BMEP. The combustion pressure and mass burn fraction (MBF) according to the control parameters and ethanol fractions were analyzed. To verify the PN oxidation characteristics of the ethanol blended fuels, the size-resolved PN emissions over the three-way catalyst (TWC) were determined with a DMS500. The peak pressure in the cylinder was similar regardless of the type of fuel and the particle emissions were reduced by 92 % compared to gasoline at the engine out position in the E85 fuel. The results show that gasoline-ethanol blends have potential as alternative fuels and are effective in reducing the particle emissions in internal combustion engines.

Sub-23 nm Solid Particle Number Emission Characteristics for a Heavy-duty Engine Fuelled with Compression Natural Gas

Cold and hot WHTC (World harmonized Transient-State Cycle) were separately run on the engine test bed for a heavy-duty natural gas engine fuelled with high calorific value natural gas and low calorific value natural gas. The particle emissions including PN10 (number of particles above 10nm) and PN23 (number of particles above 23nm) were measured. The results show that the transient emission of PN10 and PN23 have basically the same trends. The weighted specific emission of PN10 is 21.6 times of PN23. Cold start PN emissions account for a relatively large proportion. Fuel property has a great influence on the PN emissions of natural gas engines. The increase of carbon-containing fuels such as methane and ethane in the fuel gas will lead to a rapid increase in PN emissions especially in the cold start process. It is extremely important to strengthen the control of sub-23nm particulate emissions for heavy-duty natural gas engines.

Influence and strategy optimization of fuel injection timing on PN and fuel consumption

During the development of a CN Ⅵ light vehicle equipped with a GDI gasoline engine, the phenomenon of high PN appeared. In response to the operating conditions of the engine running in the WLTC cycle, a corresponding SOI sweep was performed on the dyno bench. The PN emissions of the engine has reduced by optimizing of SOI. The results show that when the SOI is sufficiently advanced, the oil film formed by the collision of the spray and the piston causes the PN emissions to increase significantly. In order to avoid the deterioration of the PN emissions, the SOI should be appropriately postponed. In the low load conditions, it is more appropriate to calibrate the SOI at 295°CA and 290°CA. In the medium speed area, it is more suitable to set it at 300°CA or later. The SOI in the higher speed area can be slightly advanced if necessary. And the impact of SOI on fuel consumption is more obvious at low speeds, but it is not obvious at the conditions of medium to high loads and speeds.

Study on fuel consumption and emission characteristics of China VI heavy duty vehicle based on vehicle specific power

This study selects a China VI heavy duty vehicle for PEMS test, and Based on the measurement results of vehicle specific power (VSP) parameters, the VSP calculation formula applicable to this study is proposed , And analyzes the distribution characteristics of VSP, and at the same time according to the fuel consumption and emission data of the actual road driving process collected by the vehicle, The effect of VSP on vehicle fuel consumption and emission characteristics and the correlation between the two are studied. Results show that VSP of the vehicle are mainly concentrated in the interval -10 ≤ VSP ≤ 10kw / t, in which the vehicle driving time accounts for about 99.3% of the total time; the correlation coefficient between VSP and average fuel consumption is about 0.93, there is a strong correlation; The changes of CO, CO2, NOX and PN with VSP all show as that under the same absolute value of VSP, the pollutants emission rate in the VSP> 0 interval is higher than the VSP <0 interval, in which the correlation between VSP and CO, CO2, PN emissions is more strong, but poorly correlated with NOX emissions.