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How well can mPEMS measure gas phase motor vehicle exhaust emissions?

Ford Motor Company-Diep Vu, Joseph Szente, Michael Loos, Matti Maricq
  • Technical Paper
  • 2020-01-0369
To be published on 2020-04-14 by SAE International in United States
“Real world emissions” is an emerging area of focus in motor vehicle related air quality. These emissions are commonly recorded using portable emissions measurement systems (PEMS) designed for regulatory application, which are large, complex and costly. Miniature PEMS (mPEMS) is a developing technology that can significantly simplify on-board emissions measurement and potentially promote widespread use. Whereas full PEMS use analyzers to record NOx, CO, and HCs similar to those in emissions laboratories, mPEMS tend to use electrochemical sensors and compact spectroscopic detectors for their small size and low cost. The present work evaluates this approach by comparing measurements of NOx, CO, CO2 and HC emissions from five commercial mPEMS to both laboratory and full regulatory PEMS measurements. It further examines the use of vehicle on-board diagnostics data to calculate exhaust flow, as an alternative to on-vehicle exhaust flow measurement. The evaluations include two vehicle types, gasoline direct injection and diesel, and employ the US EPA and Worldwide Harmonized Light duty drive cycles. The results show that two classes of electrochemical NOx sensors are capable of…
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Numerical Modeling of Spray Formation under Flash-boiling Conditions

ANSYS Inc-Mingyuan Tao, Long Liang, Yue Wang, Ellen Meeks
  • Technical Paper
  • 2020-01-0328
To be published on 2020-04-14 by SAE International in United States
Flash boiling occurs in sprays when the ambient gas pressure is lower than the saturation pressure of the injected fuel. In the present work, a numerical study was conducted to investigate solid-cone spray behaviors under various flash-boiling conditions. A new spray cone angle correlation that is a function of injection parameters was developed and used for spray initialization at the nozzle exit to capture plume interactions and the global spray shape. The spray-breakup regime control was adjusted to enable catastrophic droplet breakup, characterized by Rayleigh-Taylor (RT) breakup, near the nozzle exit. The model was validated against experimental spray data from five different injectors, including both multi-hole and single-hole injectors, with injection pressure varying from 100 to 200 bar. Different fuels, including iso-octane, n-heptane, n-pentane, ethanol, and n-butanol, were investigated under a wide range of flash-boiling conditions, in which flash boiling was induced by high injected fuel temperature, ranging from 323 to 493 K, and/or low ambient gas pressure, ranging from 0.1 bar to atmospheric. It is found that flash boiling can significantly increase the spray…
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A path towards high efficiency SI combustion in a CFR engine: Cooling the intake to sub-zero temperatures

King Abdullah University of Science & Technology-Sufyan M. Jan, Abdulrahman Mohammed, Ali Elkhazraji, Jean-Baptiste Masurier
University of California-Robert Dibble
  • Technical Paper
  • 2020-01-0550
To be published on 2020-04-14 by SAE International in United States
Textbook engine thermodynamics predicts that SI (Spark Ignition) engine efficiency η is a function of both the compression ratio CR of the engine and the specific heat ratio γ of the working fluid. In practice the compression ratio of the SI engine is often limited due to “knock”. When this knock limit is reached, increase in heat transfer losses result in reduction in efficiency. One way to lower the end-gas temperature is to cool the intake gas before inducting it into the combustion chamber. With colder intake gases, higher CR can be deployed, resulting in higher efficiencies. In this regard, we investigated the indicated efficiency of the standard Waukesha CFR engine. The engine is operated in the SI engine mode. The engine was operated with three different mediums using the same fuel Methane (Gas). First is Air + Methane at room temperature, second was O2 + Argon + Methane gas mixture at room temperature, and lastly O2 + Argon +Methane at sub-zero conditions. We replace the Air by an Oxygen-Argon mixture to increase the specific…
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The study on the influence of factors on vehicle refueling emission test

China Automotive Technology and Research-Chunbei Dai, Taiyu Zhang, Chongzhi Zhong, Qiang Chen, Jiaxing Sun, Xiaoliang Wu, Tiefei Yu
  • Technical Paper
  • 2020-01-1070
To be published on 2020-04-14 by SAE International in United States
Two vehicles with ORVR system which are met with the US standard are studied. A comparative of refueling emissions test under different refueling rate and different refueling temperature are studied. The HC chemical analysis was carried out for the fuel gas emission from a sample car. The results show that with the increase of the refueling rates, the refueling emissions decline at first, and then gradually stabilize; with the increase of the refueling temperature, the results of refueling emissions show a gradual increase. Under the condition of 37 L / min refueling flow rate and 20 ℃ fuel temperature, 14 kinds of alkanes were emitted from the fuel, in which isobutane, isopentane and n-pentane were the highest emissive components, accounting for 57.66% of the total amount of VOCs.
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Investigation of the operating conditions on the water and thermal management for a polymer electrolyte membrane fuel cell by one-dimensional model

Tongji Universtiy-Xuhui Wang, Yaqian Dong, Sichuan Xu
  • Technical Paper
  • 2020-01-0856
To be published on 2020-04-14 by SAE International in United States
Water and thermal management is an essential issue that influences performance and durability of a polymer electrolyte membrane fuel cell (PEMFC). Water content in membrane decides its ionic conductivity and membrane swelling favors the ionic conductivity, resulting in decreases in the membrane’s ohmic resistance and improvement in the output voltage. However, if excessive liquid water can’t be removed out of cell quickly, it will fill in the pores of catalyst layer (CL) and gas diffusion layer (GDL) then flooding may occur. It is essential to keep the water content in membrane at a proper level. In this work, a transient isothermal one-dimensional model is developed to investigate effects of the relative humidity of inlet gas and cell temperature on performance of a PEMFC. Comprehensive physical and chemical phenomenon inside the cell is included, especially the mass transfer of hydrogen, oxygen, vapor and liquid water in gas channels, GDL and CL and non-frozen membrane water in ionomer. Phase change between vapor and liquid water is also considered. The cell’s performances at the conditions of the different…
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Different methods to improve the exhaust gas temperature in modern stage V off-road diesel engine over transient emission cycles.

Turku University of Applied Sciences-Mika Lauren, Toomas Karhu, Miika Laivola, Jan Ekman
University of Vaasa-Seppo Niemi, Kirsi Spoof-Tuomi
  • Technical Paper
  • 2020-01-0903
To be published on 2020-04-14 by SAE International in United States
This paper presents several methods to improve the exhaust gas temperature of a modern diesel engine. A high exhaust gas temperature is needed to improve the after-treatment system efficiency and particulate filter regeneration in low engine loads. This study is based on experimental measurements of a Stage 5 level off-road diesel engine. The effect of the different heating methods determined over steady state runs and emission and performance are presented with standard emission transient test procedure (NRTC). In the first step of the study, an intake air restriction and an exhaust gas restriction method are compared. The intake restriction produces better fuel economy over the measuring cycle. However, with the exhaust restriction, higher exhaust gas temperature can be achieved in low engine loads. In the second phase of study, the intake air restriction method was implemented in the research engine. In addition, active waste gate controlling and injection retardation methods were taken in use for heating purposes. The engine performance was determined with normal calibration and with high exhaust temperature calibration. The differences to the…
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Identifying the driving processes of Diesel spray injection through mixture fraction and velocity field measurements at ECN Spray A

Eindhoven University of Technology-Bart Somers
IFP Energies Nouvelles-Louis-Marie Malbec, Gilles Bruneaux
  • Technical Paper
  • 2020-01-0831
To be published on 2020-04-14 by SAE International in United States
Diesel spray mixture formation is investigated at target conditions using multiple diagnostics and laboratories. High speed Particle Image Velocimetry (PIV) is used to measure the velocity field inside and outside the jet simultaneously with a new frame straddling synchronisation scheme. The PIV measurements are carried out in the Engine Combustion Network Spray A target conditions, enabling direct comparisons with mixture fraction measurements previously performed in the same conditions, and forming a unique database at diesel conditions. A 1D spray model, based upon mass and momentum exchange between axial control volumes and near-Gaussian velocity and mixture fraction profiles is evaluated against the data. The 1D spray model quantitatively predicts the main spray characteristics (average mixture fraction and velocity fields) within the measurement uncertainty for a wide range of parametric variations, verifying that a Diesel spray becomes momentum controlled and has a Gaussian profile. A required input to the model is the jet angle, which is obtained experimentally. Although an expected result for a gas jet, this is the first time that combined datasets of velocity and…
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Large Eddy Simulations of Supercritical and Transcritical Jet Flows using Real Fluid Thermophysical Properties

King Abdullah University of Science & Technology-Hong G. Im
Universidad de Oviedo-Adrian Pandal
  • Technical Paper
  • 2020-01-1153
To be published on 2020-04-14 by SAE International in United States
A satisfactory understanding of the complex phenomena of supercritical jet mixing is still lacking. When the injected fuel temperature and pressure are at supercritical conditions, the fuel spray becomes similar to gas jet situation and it leads to steady shock structures (Mach disk). The negligible effect of the interfacial surface tension force due to the supercritical conditions produces a diffuse interface. In order to understand supercritical jet flows further, well resolved large eddy simulations (LES) of a n-dodecane jet mixing with surrounding nitrogen are conducted. A real fluid thermodynamic model is used to account for the fuel compressibility and variable thermophysical properties due to the solubility of ambient gas and liquid jet using the cubic Peng-Robinson equation of state (PR-EOS). A molar averaged homogeneous mixing rule is used to calculate the mixing properties. The thermodynamic model is coupled with a pressure-based solver to simulate multispecies reacting flows. The numerical model is based on a second order accurate method implemented in the open source OpenFOAM-6 software. First, to evaluate the present numerical model of sprays, 1D…
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Fast Catalyst Light-off with Dynamic Skip Fire

Tula Technology Inc.-Xi Luo, Sam Hashemi, Ram Subramanian, Anastasios Arvanitis, Matthew Younkins
  • Technical Paper
  • 2020-01-0313
To be published on 2020-04-14 by SAE International in United States
Catalytic aftertreatment is commonly used to reduce toxic gas emission from internal combustion (IC). Fast catalyst light-off time is always been a challenge for automobile IC engine application. This paper experimentally studied the thermal management and toxic gas emission from spark ignition (SI) engine cold start period with dynamic skip fire (DSF). The study has found that DSF can improve up to 100 °C exhaust gas temperature at catalyst inlet, and the exhaust enthalpy increased up to 20% for catalyst heating. 10% ~20% cold start CO and HC reduction can be achieved because of increasing exhaust gas temperature and enthalpy. Dynamic air pumping can further increase 30 °C exhaust gas temperature on top of DSF benefit, and nearly doubled catalyst heating power which reduced more than 50% cold start HC emission.
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Empirical Modeling of Electrical Discharge in an Inert Medium at High-speed Flows

Michigan Technological University-Mary P. Zadeh, Henry Schmidt, Seong-Young Lee, Jeffrey Naber
  • Technical Paper
  • 2020-01-1120
To be published on 2020-04-14 by SAE International in United States
Energy discharge models have been used to gain insights into the spark discharge process and early flame kernel development in spark-ignition engines. However, the existing models are reported to be applicable for a limited range of gas pressures and flow fields. This study aims to evaluate these models and propose an improved one to predict the spark ignition at pressurized conditions up to 45 bar and high-speed flows up to 32 m/s. The model captures the spark discharge behavior that has been observed experimentally in an optically accessible constant-volume combustion vessel. This includes discharge characteristics and the occurrence of the spark blowouts and re-strikes. Results indicate that the voltage and current waveforms of the spark discharge are correlated to the flow velocity across the spark plug gap. Further investigations were performed to study the stretching rate of the spark channel under the high crossflow.