Port Fuel Injection Engines Research Articles

Effects of continuous variable valve timing and duration on fuel/air mixture formation

With increasing global regulations on particulate emissions, the particulate matter and number released under cold start and high-load conditions have become crucial. Under such conditions, the particulate emissions from port fuel injection engines can be significant and comparable to those from gasoline direct injection engines. In this case, fuel evaporation and mixture formation contribute to the reduction in particulate emissions. One method to improve these characteristics is to enhance the in-cylinder flow and turbulence kinetic energy. Therefore, in this study, we investigated the effect of in-cylinder flow enhancement on the particulate emissions reduction in port fuel injection engines. Simulations were conducted with various intake valve timings and durations under cold-start conditions. We then performed engine experiments to confirm the reduction in particulate number. The results showed that the relationship between the intake valve open timing and piston speed was crucial. Opening the intake valve to its maximum value slightly after the point of peak piston velocity resulted in a higher flow intensity and turbulence kinetic energy during the compression stroke. In addition, the experimental results indicated that improving the in-cylinder flow using continuous variable valve timing reduced the particulate number by 27.51 %.

Computational Fluid Dynamics (CFD) Validation and Investigation the Effect of Piston Bowl Geometries Performance on Port Fuel Injection-Homogeneous Charge Compression Ignition (PFI-HCCI) Engines

Computational Fluid Dynamics (CFD) Validation and Investigation the Effect of Piston Bowl Geometries Performance on Port Fuel Injection-Homogeneous Charge Compression Ignition (PFI-HCCI) Engines

Characterization of in-cylinder spatiotemporal flame and solid particle emissions for ethanol-gasoline blended in gasoline direct injection engines

Stricter regulations for internal combustion engines have necessitated the inclusion of eco-friendly fuels with conventional ones to reduce gas and solid emissions. Gasoline direct injection (GDI) engines, however, have been found to produce more particle number and mass emissions than port fuel injection engines. To address this, bioethanol fuel has been selected as an additive eco-friendly fuel for gasoline, with the aim of reducing particle emissions. In this study, we quantitatively characterize in-cylinder spatiotemporal flame to feature combustion performance and particle emissions for ethanol fuel in the GDI combustion chamber. We examined three engine combustion modes differed in equivalence ratio and injection strategy to produce various combustion results to quantify combustion performance and particle emission characteristics. Using an eight-channel non-intrusive flame luminosity sensor in one cylinder, we measured the flame front and its propagation direction. At the tailpipe, we measured particulate emissions using an engine exhaust particle sizer and a micro soot sensor coupled with a catalytic stripper that removed semi-volatile compounds. Our study found that increasing ethanol fuel content for different combustion modes resulted in distinct combustion and flame development. The particle size distribution also showed different patterns at each combustion mode, depending on the ethanol content. Lean combustion modes yielded high diffusion flame intensity compared to stoichiometric combustion mode, which resulted in a larger amount of particle formation. The physical properties of ethanol fuel were found to predominantly determine the fuel-air mixture quality, combustion process, and flame development at each combustion mode. An increase in ethanol fuel content at lean-homogeneous mode resulted in higher diffusion flame intensity and larger particle emissions. Our comparative study of flame and solid particles for ethanol fuel content improves the understanding of in-cylinder combustion processes and their correlations.

Challenges and feasibility of a six-stroke engine using water direct injection

As fuel efficiency and exhaust regulations have become more stringent, many studies have been conducted to improve fuel efficiency. One interesting proposal is to develop a six-stroke engine using water injection. However, there is a lack of research on this concept, and existing studies have only taken a theoretical approach or did not involve comparisons with a four-stroke engine, obscuring the feasibility of a six-stroke engine using water injection. So, in this study, we performed experiments and simulations of a six-stroke engine using water injection and compared the results with those of a four-stroke engine. We optimized the exhaust valve lift profile through simulation for an actual exhaust cam of the six-stroke engine, and modified a four-stroke port fuel injection engine to a six-stroke engine. Then, through experiments and simulations, we evaluated the feasibility and the challenges of building a six-stroke engine using water injection. We used the CONVERGE v2.4 software application and validated the simulation models through the results of experiments. Using these models, we conducted simulations with various injection timings, masses, and water temperatures. The results indicate that the cylinder wall is cooled due to continuous water injection making evaporation unstable and that wall-temperature control is required in order to realize a six-stroke engine using water injection. In a simulation assuming the constant temperature of the wall, as additional strokes are added, the indicated mean effective pressure (IMEP) decreases by about 0.4 bar compared to that of the four-stroke engine, and only about 40% of this loss is recovered through water injection. The wall evaporation ratio is more critical to the feasibility of the six-stroke engine using water injection than other parameters. We show that it is very difficult to achieve a six-stroke engine using water injection unless a significant amount of heat energy for evaporation is brought from sources other than the mixture in the cylinder. The challenges of a six-stroke engine using water injection were cylinder temperature control and latent heat of water. If excessive cooling does not occur, such as in steam injection, IMEP can increase due to an increase in mass. However, this is very ideal case. It is difficult to obtain energy elsewhere for evaporation, and due to the latent heat of water, the mixture is inevitably cooled down making it difficult to realize this concept of six-stroke engine.

Mixture formation characteristics and feasibility of methanol as an alternative fuel for gasoline in port fuel injection engines: Droplet evaporation and spray visualization

Under the background of energy saving and emission reduction, methanol is considered an ideal alternative fuel for gasoline because of its renewability, high combustion efficiency and low emissions, while an issue is the cold start of methanol port fuel injection engines. To comprehensively understand the underlying mechanisms and the feasibility of methanol as a substitute of gasoline, a suspension method was first used to investigate the evaporation characteristics of methanol and gasoline droplets at low temperatures. Then an optical intake port was constructed based on the outer contour modification strategy and an optical distortion correction algorithm was proposed. The effects of inlet temperature, inlet flow rate and injection pressure on spray characteristics of methanol and gasoline were comparatively investigated. In addition, the influence of valve temperature on the characteristics of spray impingement on a valve was studied. The results showed that the difference between the evaporation rates of methanol and gasoline was small at 60–90 °C. The difference became obvious when the temperature was below 60 °C or above 90 °C. Reducing the ambient humidity may reduce this difference and improve the cold start performance of methanol engines. A higher inlet temperature slightly increased the spray area. A higher inlet flow rate and injection pressure significantly increased the spray area, but also caused serious wet wall problem. From the point of view of spray in the port, methanol was a feasible substitute for gasoline in the presence of inlet flow and at low injection pressure of 6 bar. The valve temperature should exceed 200 and 230 °C for methanol and gasoline, respectively to form vapor films that prevent fuel adhesion onto the valve. However, methanol may not be a suitable alternative fuel for gasoline when spray directly impacted on the valve in port fuel injection engines due to its much smaller spray area.

Mixture Distribution in Spark Ignited Port Fuel Injection Engines: A Review

Abstract Modern gasoline engines have to meet increased stringent emission requirements along with the demand of a better fuel economy. This has led to a transition from carburetor to port fuel injection (PFI) mode in developing world for engines comprising mostly of two- and three-wheeler segments and small-scale power generation sets. Therefore, a thorough understanding on mixture formation and combustion phenomenon is needed to further enhance PFI engines. Planar laser-induced fluorescence (PLIF) has proved to be a successful optical diagnostic technique that can provide very high spatial resolution images of fuel distribution in the region of interest. This has led to a direct visualization of fuel distribution with evaluation of both spatial and temporal variations. It has furthered understanding of various engines parameters that affect mixture formation process. Various exciting concepts about fuel stratification have been proposed over the years for enhanced engine operations at lean equivalence ratios. These have been verified and optimized by information gathered from PLIF. In this review article, the authors explain mixture formation process right from the point of fuel injection in intake manifold, the subsequent formation of fuel films and its impact on engine operation. Several PLIF studies on fuel distribution, its spatial and cycle-to-cycle inhomogeneities, effects of injection timing, flow field, equivalence ratio and engine speed on mixture formation have been discussed in separate subsections. Furthermore, studies involving concepts of fuel stratification have also been briefly discussed.

ANALYSIS OF IN-CYLINDER FLOW FIELDS USING PROPER ORTHOGONAL DECOMPOSITION-BASED QUADRUPLE DECOMPOSITION

In order to meet increasingly stringent emission norms coupled with a heightened requirement of performance, there has been an unabated effort toward improvement in the combustion process of modern internal combustion engines. One of the major impediments of enhanced combustion in spark-ignited port fueled engines are combustion variations. These variations are especially dominant at low-load, low-speed operations. Cycle-to-cycle variation (CCV) in in-cylinder flow fields is one of the major contributors of such combustion variations. Therefore, in this work, CCV of in-cylinder flow fields of an optical port fuel injection engine was analyzed at part load (50% throttle opening) and low speed (1200 rpm) with the help of proper orthogonal decomposition. Flow fields were subsequently decomposed into four components, namely, mean, coherent, transition, and turbulent parts. CCV of flow fields was studied using several metrics based on kinetic energy and the relevance index. It was found that the share of mean energy is a better metric for CCV quantification based on kinetic energy. Interestingly, it was observed that the mean part, though consistent in its flow structure for various cycles, has a lot of variation in kinetic energy at early compression stroke. Also, a weak mean flow coupled with a strong coherent flow structure opposing the mean flow produces the largest deviation in a flow field from its corresponding ensemble-averaged field. Furthermore, even though the coherent and transition parts are comprised of comparable energy, it was the coherent part that showed large variations in kinetic energy. Hence, the mean and coherent parts are mainly responsible for CCV in flow fields.

Investigation of Cylinder Deactivation (CDA) Application on a Naturally Aspirated Engine

Increasing oil prices and emission legislation have forced automotive company to investigate new methods and technologies to reduce the harmful effect produced from the motor vehicle, particularly CO2 (Carbon-Dioxide).A lot of studies and research have been put into in order to achieve a zero emission vehicle with the usage of electricity rather than fossil fuel, but the challenge to cost and environmental effect makes an IC engine is still being the predominant power plant for automobile in this century. One of the popular techniques among engine manufacturers to have a better engine efficiency is cylinder deactivation. Cylinder deactivation is a promising method to reduce the fuel consumption and emission by forced the engine to operate at higher load. However, the higher combustion pressure and extreme temperature at firing cylinders will result in higher NOx composition. This paper will investigate further the engine performance, fuel economy and emission by using one-dimensional (1-D) simulation tool. A standard 1.6 litre naturally aspirated four in-line cylinders, port fuel injection engine is modelled and correlated to the measured test data. The model is then simulated with cylinder deactivation mode by deactivating the intake and exhaust valves at cylinders no 2 and no 3 as well as fuel injection at various engine speeds at part load conditions to show improvements in fuel consumption, CO2 emissions, pumping losses and effects on CO and NOx emission. This correlated model is then used to investigate the application of EGR in order to reduce the emission level. Also, the effects on in-cylinder combustion as well as pumping losses are presented. The study shows that the application of EGR is very significant for engine with CDA mechanism to ensure the overall engine fuel consumption and emissions are reduced simultaneously.

Numerical Comparative Study on the In-Cylinder Mixing Performance of Port Fuel Injection and Direct Injection Gas-Fueled Engine

In recent decades, research on alternative fuel engines is becoming more and more popular. Compressed natural gas (CNG) has the advantages of abundant reserves and a lower cost. It can reduce vehicle emissions relatively quickly and has little impact on the entire transportation infrastructure. As the fourth generation of a gas fuel supply method, gas fuel direct injection (DI) technology can effectively avoid volumetric efficiency reduction and power reduction problems of the port fuel injection (PFI) method. However, the former’s mixing path and duration are shortened greatly, which often leads to poor mixing uniformity. In order to improve the in-cylinder mixing uniformity, the in-cylinder mixing process of the CNG-fueled engine is taken as the research object in this study. The computational fluid dynamics (CFDs) models of the mixing process for the PFI and DI modes are established, and their mixing uniformities are compared. Besides, based on the authors’ previous research, the influence mechanism of the piston crown shape and fuel injection angle on the mixing process of the CNG DI engine is explored. The results show that the probability distribution frequency (PDF) of the best mixture concentration region (BMCR) is as high as 72% for the PFI mode, which is much higher than for the DI mode. The shorter jet impingement distance of the flat top piston leads to higher turbulent kinetic energy (TKE) intensity, and the in-cylinder mixing uniformity will be improved. When gas fuel is injected into an area with a higher in-cylinder TKE, the average in-cylinder TKE will be higher, and the in-cylinder mixture will be more homogeneous.

Numerical investigation of hydrogen enriched natural gas effects on different characteristics of a SI engine with modified injection mechanism from port to direct injection

This research investigates two main stages of conversion of port fuel-injected engine to direct-injection. The firs one is the modification of Injection mechanism of CNG direct-injection engine. The second stage is the investigation of Hydrogen effects as an alternative gaseous additive on CNG. The Results were measured at different injection pressures (15, 20, and 25 bar) and various hydrogen enrichment as additive fuel to CNG. At the first stage, results show that compared to the Gasoline port injection system, a CNG direct-injection engine can decrease CO2 emission up to 59.5% and increase NOx emission up to 56.9%. In the second stage, when Hydrogen being used in the fuel mixture, and an increase in the injection pressure (from 15 to 25 bar) in the DI engine along with 30%HCNG applies, the amounts of engine power and torque enhanced about 5.92% and 6.55%, respectively. Also, fuel conversion efficiency increased by up to 6.87% with 25 bar of injection pressure compared to conventional system. Emission reduction up to 32.5% for CO observed in case of using 40%HCNG relative to pure CNG. NOx emission had a reverse correlation with Hydrogen concentration, it increased about 22.5% while using 40% of Hydrogen in volumetric blend HCNG.

Reproducibility of the 10-nm Solid Particle Number Methodology for Light-Duty Vehicles Exhaust Measurements

Many countries worldwide have introduced a limit for solid particles larger than 23 nm for the type approval of vehicles before their circulation in the market. However, for some vehicles, in particular for port fuel injection engines (gasoline and gas engines) a high fraction of particles resides below 23 nm. For this reason, a methodology for counting solid particles larger than 10 nm was developed in the Particle Measurement Programme (PMP) group of the United Nations Economic Commission for Europe (UNECE). There are no studies assessing the reproducibility of the new methodology across different laboratories. In this study we compared the reproducibility of the new 10 nm methodology to the current 23 nm methodology. A light-duty gasoline direct injection vehicle and two reference solid particle number measurement systems were circulated in seven European and two Asian laboratories which were also measuring with their own systems fulfilling the current 23 nm methodology. The hot and cold start emission of the vehicle covered a range of 1 to 15 × 1012 #/km with the ratio of sub-23 nm particles to the >23 nm emissions being 10–50%. In most cases the differences between the three measurement systems were ±10%. In general, the reproducibility of the new methodology was at the same levels (around 14%) as with the current methodology (on average 17%).

Effect of fuel injection timing and injection pressure on performance in a hydrogen direct injection engine

The in-cylinder hydrogen fuel injection method (diesel engine) induces air during the intake stroke and injects hydrogen gas directly into the cylinder during the compression stroke. Fundamentally, because hydrogen gas does not exist in the intake pipe, backfire, which is the most significant challenge to increasing the torque of the hydrogen port fuel injection engine, does not occur. In this study, using the gasoline fuel injector of a gasoline direct-injection engine for passenger vehicles, hydrogen fuel was injected at high pressures of 5 MPa and 7 MPa into the cylinder, and the effects of the fuel injection timing, including the injection pressure on the output performance and efficiency of the engine, were investigated. Strategies for maximizing engine output performance were analyzed.The fuel injection timing was retarded from before top dead center (BTDC) 350 crank angle degrees (CAD) toward top dead center (TDC). The minimum increase in the best torque ignition timing improved, and the efficiency and excess air ratio increased, resulting in an increase in torque and decrease in NOx emissions. However, the retardation of the fuel injection timing is limited by an increase in the in-cylinder pressure. By increasing the fuel injection pressure, the torque performance can be improved by further retarding the fuel injection timing or increasing the fuel injection period. The maximum torque of 142.7 Nm is achieved when burning under rich conditions at the stoichiometric air-fuel ratio.

Numerical Investigations of Injection Timing Effects on a GDI Engine Performance: Part B, In-Cylinder Emission Formation and Oxidation Process

The emphasis on environmental protection and energy security has promoted automobile engine technology toward low emission and economy. While the traditional port fuel injection engine can hardly meet the latest regulations and requirements, the gasoline direct injection (GDI) engine becomes a hot research topic because of its potential to reduce fuel consumption and emissions. Since injection timing has a determining effect on overall engine performance, this paper aimed to investigate the injection timing effects on mixture formation and emissions. A validated three-dimensional numerical simulation model of a 4-stroke GDI engine combustion chamber was adopted. In a previous work (Part A), the in-cylinder combustion process has been discussed. In this study, the simulation results demonstrate that with the injection timing advancing, the fuel–gas mixture was more uniformly distributed and combusted more completely; the CO, UHC, and soot had decreased sharply by 80.6, 99.2, and 97.5%; the NOx emission increased by 151.7%. The optimized injection timing for this case was 300 CA BTDC. Moreover, this paper studied the in-cylinder views of injection timing effects on mixture formation and emission, providing reference to optimize injection of GDI engine.

Gasoline Direct Injection Engine Emissions of OC and EC: Laboratory Comparisons with Port Fuel Injection Engine

To better understand carbonaceous aerosol emissions from gasoline vehicles, a gasoline direct injection (GDI) vehicle with and without a gasoline particle filter (GPF) installed and a port fuel injection (PFI) vehicle were tested on a chassis dynamometer using standard emission drive cycles. Carbonaceous particles emitted from the vehicles were collected on quartz filters and analyzed using three different thermal optical protocols to assess the sensitivity of organic carbon (OC) and elemental carbon (EC) emission estimates to the methods, showing OC obtained by the IMPROVE and EC by the NIOSH protocol was the lowest. Compared to the PFI vehicle, the GDI vehicle had higher EC and OC emissions under cold-start cycles by 1415% and 46%, respectively. However, the OC emission from the PFI vehicle was higher than GDI during an aggressive driving cycle by 146%. By considering OC collected on a quartz filter behind a Teflon filter, the emissions from PFI vehicle were found to be more volatile than the GDI vehicle. This is consistent with the OC forming characteristics for GDI and PFI engines, which are pyrolyzed particles from incomplete combustion and incomplete volatilization of fuel droplets, respectively. Generally, the particle phase OC emissions from gasoline engines are more volatile than other sources (e.g., biomass burning), supported by the very low level of pyrolyzed organic carbon (POC) and small differences among protocols in the current study. Once the GDI vehicle was equipped with a GPF, the removal efficiency of EC was > 98%, but OC emissions could increase as a result of regeneration, suggesting that the effect of a GPF on total carbon emitted to the atmosphere needs further evaluation, especially considering the formation of secondary organic aerosol.

Research on evaporation and mixture process in gdi engine using numerical simulation method

GDI engines indicated an improvement in fuel efficiency and reducing emission in comparison with intake port-fuel injection engines. This study research the behaviors of injected fuel into the GDI engine chamber for a part load. The study focus on the mixture process after fuel injection in compression stroke (from 60oCA BTDC to 40oCA BTDC). The study results indicated that the gasoline evaporation process will absorb an amount of heat from compressed air. This is an advantage factor for increasing of compression ratio. During the injection process and after injection, the fuel within the combustion chamber nearly touches the top surface of the piston. Moreover, the study also shows the vapor delay timing of fuel in the chamber.

Optical screening investigations of backfire in a large bore medium speed hydrogen engine

Further improvement of hydrogen combustion in port fuel injection engines is limited by backfire. To overcome this drawback of hydrogen port fuel injection engines it is essential to locate and understand the reasons for the inflammation of a backfiring cycle. To contribute to this understanding a minimal invasive lateral optical access was developed for a medium speed large bore engine. The access uses a UV enhanced endoscope to investigate the OH radical’s natural chemiluminescence to locate the inflammation of a backfiring cycle in the combustion chamber. The investigations are carried out at high engine load. The optical investigations were based on a thermodynamic screening. This included the variation of the start of the hydrogen port fuel injection and the engine’s backpressure. These experiments prove the influence of exhaust backpressure and the start of injection on the probability of backfire. As higher backpressure leads to an increased probability of backfire, the SoI strategy has also a decisive influence. An optimum start of injection timing with less backfire under high backpressure was experimentally determined at 300°CA with respect to 720°CA as FTDC. The conducted optical investigations show that backfire starts by ignition by hot residual gasses during the first cycle located under the exhaust valves. Furthermore, the results show ongoing combustion in the intake manifold leading to serious damage of the engine if not prohibited.

Effect of the operation strategy and spark plug conditions on the torque output of a hydrogen port fuel injection engine

A port injection engine that supplies hydrogen to the intake manifold or port exhibits a low intake air amount and torque output. The torque output is limited by backfire. In the present study, the performance and efficiency of a port injection-type hydrogen engine using the fuel injector of a natural gas engine is investigated at various engines speeds under wide open throttle conditions and two operation strategies, i.e., limiting nitrogen oxide emission and maximizing the torque. The increase in electrode temperature is reduced by increasing the heat rating number of the spark plug or reducing the ignition energy applied to the spark plug. Even when the ignition energy is reduced, as the minimum ignition energy of hydrogen is very low, it does not eliminate backfire. However, when a cold-type spark plug is used, backfire is effectively suppressed, resulting in an increase in the maximum torque and a decrease in efficiency.

Effect of boosting on a performance and emissions in a port fuel injection natural gas engine with variable intake and exhaust valve timing

Recently, many studies have been conducted on the conversion of conventional fossil fuels to alternative fuels. Natural gas is one of the best alternative fuels because it is a low-carbon fuel. In natural gas engines, port fuel injection is generally adopted rather than direct injection because of the compatibility of the injection system in a positive ignition engine. However, methane, of which the global warming potential is 28 times than that of carbon dioxide, is highly likely to emit during the valve overlap in port fuel injection engines. The methane slip phenomenon could be reduced by changing the intake and exhaust valve timing. However, few studies have discussed engine performance and emission characteristics through valve timing changes in natural gas engines. Therefore, in this study, experiments were conducted under the valve timing variations with/without boosting in a natural gas engine. Through experiments, it was possible to investigate the trend of engine performance and methane emission according to the change in the intake and exhaust valve timing. As a result, under the boosted condition, the intake valve timing could only be advanced up to 45 CAD bTDC and the exhaust valve timing could only be retarded by 27.4 CAD bBDC. This is because the methane slip phenomenon increased and it resulted in a decrease of engine torque when the intake valve timing was excessively advanced or the exhaust valve timing was inordinately retarded under the boosted condition. In addition, considering a level of methane emission equivalent to EURO-6, the valve timings were optimized for each engine speed point of 1000–2500 rpm under boosted high load conditions. It was found that the trend of intake valve timing of the natural gas engine was unlike that of the conventional gasoline engine under the low engine speed of less than 2500 rpm.

On Direct Injection of Supercritical Water into Spark Ignition Engines as a Strategy for Heat Recovery

A novel heat recovery strategy for internal combustion engines is proposed. The aim is to recover thermal energy from the engine exhaust gases and through cylinder walls to heat pressurized water to supercritical conditions and to directly inject such supercritical water into the combustion chamber. Herein, this strategy is applied to a spark ignition, four‐stroke, port fuel injection engine. An in‐house solver, which includes a heat exchanger model, has been developed to conduct numerical simulations of the apparatus. At first, the engine model has been validated by comparing the results with experimental measurements. Then, a parametric analysis has been conducted to maximize the engine efficiency by varying the injection start timing, the injector diameter, and the water/fuel ratio. A single‐objective genetic algorithm has been used to select the optimal set of such parameters. Finally, a multiobjective genetic algorithm has been used to maximize the engine efficiency and minimize the exhaust gas–water heat exchanger size. The results show that the proposed approach may lead to a significant increase in the engine efficiency, up to about 12%.

Using an oxidation flow reactor to understand the effects of gasoline aromatics and ethanol levels on secondary aerosol formation

Fuel type and composition affect tailpipe emissions and secondary aerosol production from mobile sources. This study assessed the influence of gasoline fuels with varying levels of aromatics and ethanol on the primary emissions and secondary aerosol formation from a flexible fuel vehicle equipped with a port fuel injection engine. The vehicle was exercised over the LA92 and US06 driving cycles using a chassis dynamometer. Secondary aerosol formation potential was measured using a fast oxidation flow reactor. Results showed that the high aromatics fuels led to higher gaseous regulated emissions, as well as particulate matter (PM), black carbon, and total and solid particle number. The high ethanol content fuel (E78) resulted in reductions for the gaseous regulated pollutants and particulate emissions, with some exceptions where elevated emissions were seen for this fuel compared to both E10 fuels, depending on the driving cycle. Secondary aerosol formation potential was dominated by the cold-start phase and increased for the high aromatics fuel. Secondary aerosol formation was seen in lower levels for E78 due to the lower formation of precursor emissions using this fuel. In addition, operating driving conditions and aftertreatment efficiency played a major role on secondary organic and inorganic aerosol formation, indicating that fuel properties, driving conditions, and exhaust aftertreatment should be considered when evaluating the emissions of secondary aerosol precursors from mobile sources.