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Technical Paper

Application of a Biodegradable Lubricant in a Diesel Vehicle

The IEA Advanced Motor Fuels Agreement has initiated this project concerning the application of biodegradable lubricants to diesel and gasoline type vehicles. Emission measurements on a chassis dynamometer were carried out. The purpose of these measurements was to compare the emissions of CO, CO2, NOx, THC, PM, lubricant-SOF and PAH from one diesel and one gasoline type vehicle using biodegradable lubricants and conventional lubricants. This paper describes the results of the experiments with the diesel type vehicle only. Lubricant consumption and fuel consumption are other important parameters that have been evaluated during the experiments. Both vehicle types were operated on conventional crude oil based fuels and alternative fuels. The diesel vehicle was operated on conventional diesel fuel from a Danish fuel station, low sulfur diesel from Sweden and biodiesel, which was bought at a fuel station in Germany.
Technical Paper

The Role of Post Flame Oxidation on the UHC Emission for Combustion of Natural Gas and Hydrogen Containing fuels.

In-cylinder post flame oxidation of unburned hydrocarbons from crevices in a lean burn spark ignition engine has been examined for natural gas and mixtures of natural gas and a hydrogen containing producer gas. For this purpose a model was developed to describe the mixing of cold unburned reactants from crevices and hot burned bulk gas and to describe the oxidation of the unburned fuel. The post oxidation was described by a single step chemical reaction mechanism instead of detailed chemical kinetics in order to reduce the calculation time. However, the exploited Arrhenius expressions used to describe the chemical reactions were deduced from a detailed reaction mechanism. Different detailed reaction mechanisms were compared with results from combustion reactor experiments. Experiments and simulations were compared at different pressures and excesses of air similar to the conditions present during in-cylinder post oxidation.
Technical Paper

Analysis of UHC Emission from a Natural Gas SI Engine Using Fast Response FID and a Heat Release Model

Lean burn operation is often used for improving the efficiency of SI engines. However, as a draw back, this method leads to a higher emissions of Unburned Hydro-Carbons, UHC, compared to stoichiometric combustion. In order to gain a better understanding of what is causing the higher UHC emission at lean burn condition, engine experiments have been carried out on a four-cylinder natural gas fueled SI engine. The concentration of UHC in the exhaust manifold and the HC concentration in the vicinity of the spark plug have been measured during the experiments using a Fast Response FID (FFID) analyzer. Using a model describing the outflow from the cylinder during the exhaust stroke and the measured UHC concentration in the manifold near the exhaust valve, the UHC emissions from the individual cycles have been determined. The investigation showed that under lean burn conditions, cycle by cycle variation had a significant importance on the total UHC emission from the engine.
Technical Paper

Hydrocarbon Emission from Combustion of Mixtures of Natural Gas and Hydrogen Containing Producer Gas in a SI Engine

Engine experiments have been conducted on a gas fueled SI engine. The engine was fueled with natural gas and mixtures of natural gas and hydrogen containing producer gas in order to examine the effect of addition of producer gas on the combustion process and the engine-out emissions. The experiments showed that addition of producer gas decreased the UHC emission at conditions leaner than λ=1.40. The CO emission was increased by addition of producer gas. This was mainly caused by unburned fuel CO from the producer gas. No effect of producer gas on the NOx emission was detected. Formaldehyde, which is suspected to cause odor problems from natural gas fired engine based power plants, was measured using FTIR. The investigation showed that the formaldehyde emission was decreased significantly by addition of producer gas to natural gas.
Technical Paper

Hydrocarbon Emissions from a SI Engine Using Different Hydrogen Containing Gaseous Fuels

Experiments have been conducted on a gas fueled spark ignition engine using natural gas and two hydrogen containing fuels. The hydrogen containing fuels are Reformulated Natural Gas (RNG) and a mixture of 50% (Vol.) natural gas and 50% (Vol.) producer gas. The producer gas is a synthetic gas with the same composition as a gas produced by gasification of biomass. The hydrocarbon emission, measured as the percentage of hydrocarbons in the fuel, which passes unburned through the engine, was for the mixture of natural gas and producer gas up to 50% lower than the UHC emissions using natural gas as fuel. The UHC emission from the experiments using reformulated natural gas was 15% lower at lean conditions. Furthermore, both hydrogen-containing fuels have a leaner lean burn limit than natural gas. The combustion processes from the experiments have been analyzed using a three-zone heat release model, which is taking the effect of crevices into account.
Technical Paper

A Three-Zone Heat Release Model for Combustion Analysis in a Natural Gas SI Engine. -Effects of Crevices and Cyclic Variations on UHC Emissions

A thermodynamic analysis based on a pressure-time history measured during the combustion in a SI engine is a commonly used tool used for analyzing the combustion process. Both one-zone and two-zone models have been applied for this purpose. One of the major sources of the emission of unburned hydrocarbons from SI engines is the presence of crevices in the combustion chamber where a part of the unburned fuel-air mixture is trapped during the compression and the combustion. In this paper a three-zone heat release model including the effect of crevices is presented. The model is based on a thermodynamic analysis of three connected zones consisting of burned gas, unburned gas and gas trapped in crevices. Engine experiments have been carried out on a natural gas SI engine. The results from these experiments have been analyzed by the model.
Technical Paper

Application of a Bituminous Fuel in Diesel Engines

Engine experiments with a 0.964 l. DI diesel engine have been carried out applying mixtures of diesel and bitumen as fuel. These investigations showed that there is an increase in emissions of CO, NOx, PM1 and SOF2 as the share of bitumen in the fuel increases. Sampled PM from the exhaust gas from a 0.296 ltr. DI diesel engine was analysed for its contents of 16 specific PAH-compounds. The results showed that the emission of PAH in the exhaust gas was significantly lower for mixtures of bitumen/diesel than for mixtures of heavy-fuel-oil/diesel. Seven different components where detected. Analysis of soot deposits from the combustion chamber and of the crank case lubricant concerning magnesium, vanadium and nickel have been carried out. The results showed that 2-5% of the amount of metals in the injected fuel could be found in the engine lubricant. Only a small amount of magnesium and vanadium was detected in the soot.
Technical Paper

Emissions from a Diesel Vehicle Operated on Alternative Fuels in Copenhagen

A new diesel van with a reference weight of 1661 kg and a pre-chamber engine with a displacement of 2400cc was tested on a chassis dynamometer. The fuel consumption and emissions of carbon monoxide, unburned hydrocarbons, nitrogen oxides, carbon dioxide, particulate matter and associated organic material (SOF) as well as PAH (Polycyclic Aromatic Hydrocarbons) were measured under different driving conditions. The driving patterns used were recorded with a chase car at real traffic conditions on several roads in Copenhagen. The emissions were measured using different kind of diesel fuels as well as RME and biodiesel. CO, CO2, HC, and NOx levels generally decreased with increasing average speed of the driving cycle for all fuels tested. Cold start emissions were generally higher than for warm start.
Technical Paper

Unburned Hydrocarbon Emissions from SI Engines Using Gaseous Fuels

Experimental investigations with a combustion bomb have been carried out with mixtures of methane and producer gas produced by thermal gasification of biomass. The investigations showed that the lamin ar flame speed increased and the amount of UHC decreased for increasing amount of producer gas in the fuel. Application of mathematical models for calculations of quench distances near the bomb walls and post oxidation reactions has led to the conclusion that the amount of unburned fuel is reduced primarily due to a promotion of post oxidation processes. Engine experiments have been carried out applying mixtures of natural gas and gasification gas as fuel for different air-fuel ratios. These investigation showed that substituting 16% (Vol.) of the natural gas by producer gas resulted in a decrease of 50% (Vol.) of the UHC from the combustion for lean mixtures.
Technical Paper

Simulation of HC-Emissions from SI-Engines - A Parametric Study

Earlier modelling of SI engine HC-emissions indicated that the absorption/desorption of fuel HC in the oil film played a rather important role for the engine-out HC-emissions. However, recent experimental results seem to indicate that this mechanism does not play a major role. Therefore, we updated a previous model in order to obtain a better understanding of the absorption/desorption phenomenon. The upgraded absorption/desorption model has been combined with the MIT ring/liner lubrication model and applied to a single cylinder engine with known lubrication characteristics. The calculations have been carried out for steady-state and warm-up conditions. Compared to earlier results we found that due to an essentially smaller oil film thickness calculated by the lubrication model the absorption/desorption process exhibits a much faster response than previously estimated.
Technical Paper

Conventional Event Based Engine Control

Many existing production engine controllers use event (or constant crank angle increment) based sampling and computation systems. Because the engine events are synchronized to the internal physical processes of an engine, it is widely accepted that this is the most logical approach to engine control. It is the purpose of this paper to deal with this assumption in detail and to illuminate various failures of it in practical systems. The approach of the paper is in terms of overall general control system design. That is to say that the problem of event based engine control is considered as a general control problem with its standard components: 1. modelling (engine plus actuator/sensor), 2. specification of desired performance goals, 3. control system design method selection and 4. experimental testing.
Technical Paper

Nonlinear, Closed Loop, SI Engine Control Observers

Conventional electronic engine control systems suffer from poor transient air/fuel ratio control accuracy. This is true of speed-throttle, speed-density, and mass air flow (MAF) control systems with either single point (or central) or port fuel injection. The reason for this is that they fail to 1. compensate for the nonlinear dynamics of the fuel film in the intake manifold or in the vicinity of the intake valves. 2. estimate correctly the air mass flow at the location of the injector(s). This paper presents a nonlinear fuel film compensation network and a nonlinear closed loop observer. The nonlinear fuel film compensator gives improved global cancellation of the fuel film dynamics, while the closed loop observer has improved robustness with respect to modelling error and measurement noise. The closed loop observer is based on a modified constant gain extended Kalman filter.