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Monitoring NO2 Production of a Diesel Oxidation Catalyst

2012-01-24
A combination of laboratory reactor measurements and vehicle FTP testing has been combined to demonstrate a method for diagnosing the formation of NO2 from a diesel oxidation catalyst (DOC). Using small cores from a production DOC and simulated diesel exhaust, the laboratory reactor experiments are used to support a model for DOC chemical reaction kinetics. The model we propose shows that the ability to produce NO2 is chemically linked to the ability of the catalyst to oxidize hydrocarbon (HC). For thermally damaged DOCs, loss of the HC oxidation function is simultaneous with loss of the NO2 production function. Since HC oxidation is the source of heat generated in the DOC under regeneration conditions, we conclude that a diagnostic of the DOC exotherm is able to detect the failure of the DOC to produce NO2. Vehicle emissions data from a 6.6 L Duramax HD pick-up with DOC of various levels of thermal degradation is provided to support the diagnostic concept.
Technical Paper

Knock Detection and Estimation Based on Heat Release Strategies

2011-04-12
2011-01-1409
Engine knock has been studied extensively over the years. Its undesired effects on drivability, its potential to damage an engine, and its impact on limiting the compression ratio are the main reasons why it remains a current topic of research. This paper focuses on exploiting the connection between auto-ignition and knock. A new method based on the frequency analysis of the heat release traces is proposed to detect and estimate auto-ignition/knock robustly. Filtering the heat release signal with the appropriate bandwidth is crucial to avoid misdetection. The filter settings used in this paper are found using spectral analysis of the heat release signal. By using the proposed method, it is possible to detect auto-ignition/knock even under the presence of undesired sensor resonance effects and noise from mechanical and electrical sources.
Technical Paper

Cellulosic Ethanol Fuel Quality Evaluation and its Effects on PFI Intake Valve Deposits and GDI Fuel Injector Plugging Performance

2013-04-08
2013-01-0885
The U.S. Renewable Fuel Standard 2 (RFS2) mandates the use of advanced renewable fuels such as cellulosic ethanol to be blended into gasoline in the near future. As such, determining the impact of these new fuel blends on vehicle performance is important. Therefore, General Motors conducted engine dynamometer evaluations on the impact of cellulosic ethanol blends on port fuel injected (PFI) intake valve deposits and gasoline direct injected (GDI) fuel injector plugging. Chemical analysis of the test fuels was also conducted and presented to support the interpretation of the engine results. The chemical analyses included an evaluation of the specified fuel parameters listed in ASTM International's D4806 denatured fuel ethanol specification as well as GC/MS hydrocarbon speciations to help identify any trace level contaminant species from the new ethanol production processes.
Technical Paper

Experimental Investigation of Light-Medium Load Operating Sensitivity in a Gasoline Compression Ignition (GCI) Light-Duty Diesel Engine

2013-04-08
2013-01-0896
The light-medium load operating range (4-7 bar net IMEP) presents many challenges for advanced low temperature combustion strategies utilizing low cetane fuels (specifically, 87-octane gasoline) in light-duty, high-speed engines. The overly lean overall air-fuel ratio (Φ≺0.4) sometimes requires unrealistically high inlet temperatures and/or high inlet boost conditions to initiate autoignition at engine speeds in excess of 1500 RPM. The objective of this work is to identify and quantify the effects of variation in input parameters on overall engine operation. Input parameters including inlet temperature, inlet pressure, injection timing/duration, injection pressure, and engine speed were varied in a ~0.5L single-cylinder engine based on a production General Motors 1.9L 4-cylinder high-speed diesel engine.
Journal Article

Calculation of Heating Value for Diesel Fuels Containing Biodiesel

2013-04-08
2013-01-1139
Biodiesel, a fuel comprised of mono-alkyl esters of long-chain fatty acids also known as Fatty Acid Methyl Esters(FAME), derived from vegetable oils or animal fats, has become an important commercial marketplace automotive fuel in the United States (US) and around the world over last few years. FAME biodiesels have many chemical and physical property differences compared to conventional petroleum based diesel fuels. Also, the properties of biodiesel vary based on the feedstock chosen for biodiesel production. One of the key differences between petroleum diesel fuels and biodiesel is the energy content. The energy content, or heating value, is an important property of motor fuel, since it directly affects the vehicle fuel economy. While the energy content can be measured by combustion of the fuel in a bomb calorimeter, this analytical laboratory testing is time consuming and expensive.
Journal Article

Gasoline DICI Engine Operation in the LTC Regime Using Triple- Pulse Injection

2012-04-16
2012-01-1131
An investigation of high speed direct injection (DI) compression ignition (CI) engine combustion fueled with gasoline injected using a triple-pulse strategy in the low temperature combustion (LTC) regime is presented. This work aims to extend the operation ranges for a light-duty diesel engine, operating on gasoline, that have been identified in previous work via extended controllability of the injection process. The single-cylinder engine (SCE) was operated at full load (16 bar IMEP, 2500 rev/min) and computational simulations of the in-cylinder processes were performed using a multi-dimensional CFD code, KIVA-ERC-Chemkin, that features improved sub-models and the Chemkin library. The oxidation chemistry of the fuel was calculated using a reduced mechanism for primary reference fuel combustion chosen to match ignition characteristics of the gasoline fuel used for the SCE experiments.
Journal Article

Fundamental Approach to Investigate Pre-Ignition in Boosted SI Engines

2011-04-12
2011-01-0340
A comprehensive experimental and theoretical approach was undertaken to understand the phenomenon of pre-ignition and to assess parameters to improve or even eliminate it completely. Oil mixing with fuel was identified as the leading theory of self ignition of the fuel. End of compression temperature has to meet a minimum level for pre-ignition to take place. In this work a comprehensive list of parameters were identified that have a direct and crucial role in the onset of pre-ignition including liner wetting, injection targeting, stratification, mixture motion and oil formulation. Many secondary effects were identified including ring dynamics, ring tension, spark plug electrode temperature and coolant temperature. CFD has been extensively used to understand test results including wall film, A/F ratio distribution and temperature at the end of compression when looked at in the context of fuel evaporation and mixing.
Technical Paper

Effects of Fuel Corrosion Inhibitors on Powertrain Intake Valve Deposits

2011-04-12
2011-01-0908
Corrosion inhibitors (CIs) have been used for years to protect the supply and distribution hardware used for transportation of fuel from refineries. The impact of these inhibitors on spark ignited fuel systems, specifically intake valve deposits, is known and presented in open literature. However, the relationship of the additive concentrations to the powertrain intake valve deposit performance is not understood. This paper has two purposes: to present and discuss a market place survey of corrosion inhibitors and how they vary in concentration in the final blended fuel; and, to show how the variation in the concentrations of the CIs impact the operation and performance of vehicles, specifically, the effects on intake valve deposit formation. Commercially available corrosion inhibitor packages for both gasoline and ethanol blended fuels, specifically E85 fuels, were studied for their chemical compositions, and their impact on valves for a port fuel injection (PFI) engine.
Journal Article

Effects of Gasoline and Ethanol Fuel Corrosion Inhibitors on Powertrain Intake Valve Deposits

2013-04-08
2013-01-0893
Corrosion inhibitors (CIs) have been used for years to protect the supply and distribution hardware used for transportation of fuel from refineries and to buffer the potential organic acids present in an ethanol blended fuel to enhance storage stability. The impact of these inhibitors on spark-ignition engine fuel systems, specifically intake valve deposits, is known and presented in open literature. However, the relationship of the corrosion inhibitors to the powertrain intake valve deposit performance is not understood. This paper has two purposes: to present and discuss a second market place survey of corrosion inhibitors and how they vary in concentration in the final blended fuel, specifically E85 (Ethanol Fuel Blends); and, to show how the variation in the concentrations of the components of the CIs impacts the operation and performance of vehicles, specifically, the effects on intake valve deposit formation.
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