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Diesel spray experimentation at controlled high-temperature and high-pressure conditions is intended to provide a more fundamental understanding of diesel combustion than can be achieved in engine experiments. This level of understanding is needed to develop the high-fidelity multi-scale CFD models that will be used to optimize future engine designs. Several spray chamber facilities capable of high-temperature, high-pressure conditions typical of engine combustion have been developed, but because of the uniqueness of each facility, there are uncertainties about their operation. For this paper, we describe results from comparative studies using constant-volume vessels at Sandia National Laboratories and IFP.

A model which calculates the hydrocarbon emissions from an SI engine is presented. The model was developed in order to obtain a better under-standing of experimental results from an engine operating on different fuels and lubricants. The model is based on the assumptions that fuel is stored in crevices and oil film during intake and compression followed by desorption during expansion and exhaust. The model also calculates the amount of desorbed material that undergoes in cylinder oxidation and exhaust port oxidation. The model succesfully predicts the trends followed by varying different engine parameters. The effect of changing the lubricant is of the same order of magnitude as found experimentally, but the effect of changing the fuel could not be predicted very well by the model. A possible explanation is, that the lubricant film thickness varies due to viscosity variations of the oil film, when the fuel is dissolved in the film.

The aim of this study is to evaluate the existing chemical kinetic mechanism reduction techniques. From here, an appropriate reduction scheme was developed to create compact yet comprehensive surrogate models for both diesel and biodiesel fuels for diesel engine applications. The reduction techniques applied here were Directed Relation Graph (DRG), DRG with Error Propagation, DRG-aided Sensitivity Analysis, and DRG with Error Propagation and Sensitivity Analysis. Nonetheless, the reduced mechanisms generated via these techniques were not sufficiently small for application in multi-dimensional computational fluid dynamics (CFD) study. A new reduction scheme was therefore formulated. A 68-species mechanism for biodiesel surrogate and a 49-species mechanism for diesel surrogate were successfully derived from the respective detailed mechanisms.

This work is an extension to a previously reported work on chemical kinetic mechanism reduction scheme for large-scale mechanisms. Here, Perfectly Stirred Reactor (PSR) was added as a criterion of data source for mechanism reduction instead of using only auto-ignition condition. As a result, a reduced n-hexadecane mechanism with 79 species for diesel fuel surrogate was successfully derived from the detailed mechanism. Following that, the reduced n-hexadecane mechanism was validated under auto-ignition and PSR conditions using zero-dimensional (0-D) closed homogeneous batch reactor in CHEMKIN-PRO software. Agreement was achieved between the reduced and detailed mechanisms in ignition timing predictions and the reduced n-hexadecane mechanism was able to reproduce species concentration profiles with a maximum error of 40%. Accordingly, two-dimensional (2-D) Computational Fluid Dynamic (CFD) simulations were performed to study the spray combustion phenomena within a constant volume bomb.

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.

The described investigation was carried out under the umbrella of IEA Advanced Motor Fuels Agreement. The purpose was to evaluate the emissions of carbon monoxide (CO), unburned hydrocarbons (HC), nitrogen oxides (NOx), particulate matter (PM) and polycyclic aromatic hydrocarbons (PAH) from vehicles fuelled by Fischer Tropsch (FT) based diesel and gasoline fuel, compared to the emissions from ordinary diesel and gasoline. The comparison for diesel fuels was based on a literature review, whereas the gasoline comparison had to be based on our own experiments, since almost no references were found in this field. In this context measurement according to the Federal Test Procedure (FTP) and the New European Driving Cycle (NEDC) were carried out on a chassis dynamometer with a directly injected gasoline vehicle. Experiments were carried out with a reference fuel, a fuel based 70% on FT and an alkylate fuel (Aspen), which was taken to be the ultimate formula of FT gasoline.

An experimental study has been carried out on the homogeneous charge compression ignition (HCCI) combustion of Dimethyl Ether (DME). The study was performed as a parameter variation of engine speed and compression ratio on excess air ratios of approximately 2.5, 3 and 4. The compression ratio was adjusted in steps to find suitable regions of operation, and the effect of engine speed was studied at 1000, 2000 and 3000 RPM. It was found that leaner excess air ratios require higher compression ratios to achieve satisfactory combustion. Engine speed also affects operation significantly.

A novel base metal-palladium catalytic coating was applied on commercial silicon carbide wall flow diesel filters and tested in an engine test bench. This catalytic coating limits the NO2 formation and even removes NO2 within a wide temperature range. Soot combustion, HC conversion and CO conversion properties are comparable to current platinum-based coatings, but at a lower cost. This paper compares the results from engine bench tests of present commercial solutions as regards NO2-, HC-, CO-removal and soot combustion with the novel coating. Furthermore, emission test results from base metal-palladium coated diesel particulate filters installed on operating taxis and related test cycle data are presented. A significant reduction in NO2 emission compared to present technology is measured.

The low auto-ignition temperature, rapid evaporation and high cetane number of dimethyl ether (DME) enables the use of low-pressure direct injection in compression ignition engines, thus potentially bringing the cost of the injection system down. This in turn holds the promise of bringing CI efficiency to even the smallest engines. A 50cc crankcase scavenged two-stroke CI engine was built based on moped parts. The major alterations were a new cylinder head and a 100 bar DI system using a GDI-type injector. Power is limited by carbon monoxide emission but smoke-free operation and NOx < 200ppm is achieved at all points of operation.

Seven shapes of piston crowns have been evaluated for their ability to reduce HCCI knock and transmission of combustion noise to the engine. The performance of each piston crown was evaluated with measurements of cylinder pressure, engine vibration and acoustic sound pressure measured one meter away from the engine. The experiments were conducted in a diesel engine that was run in HCCI combustion mode with a fixed quantity of DME as fuel. The results show that combustion knock is effectively suppressed by limiting the size of the volume in which the combustion occurs. Splitting the compression volume into four smaller volumes placed between the perimeter of the piston and the cylinder liner increased the noise to a higher level than that generated with a flat piston crown. This was due to resonance between the four volumes. Using eight volumes instead decreased the noise.

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.

The utilisation of producer gas - from thermal gasification of biomass - as a fuel for spark ignition gas engines is of vital importance to the ongoing effort of making biomass gasification a commercially feasible technology. Tests have been carried out with a 1.1 litre four-cylinder natural aspirated SI engine in conjunction with a two-stage gasifier with a nominal thermal input of 100 kW. The fuel-gas is produced from wood chips in order to get a CO2 neutral fuel for combined heat and power production. The producer gas has a very low tar and particulate content and high hydrogen content. As the gasifier was operated with varying fuel properties, engine tests were made with different fuel-gas compositions. The engine tests showed that producer gas has a power and efficiency advantage compared to natural gas when operating the engine at lean burn conditions. The engine was operated at air/fuel ratios varying from stoichiometric to extremely lean burn (λ>3).

Investigations were made concerning the formation of combustion chamber deposits (CCD) in SI gas engines fueled by producer gas. The main objective was to determine and characterise CCD and PAH formation caused by the presence of the light tar compounds phenol and guaiacol in producer gas from an updraft gasifier. The work was based on previous work regarding the assumption that phenol is a soot precursor and therefore could lead to CCD formation. Laboratory experiments were conducted, where pyrolysis products of the single tar components were collected on small aluminium plates. The experiments showed that guaiacol formed significant amount of deposits. The structure observed was a lacquer type of deposit. It was determined that there was no distinct deposit formation due to phenol. Experiments were conducted with a 0.48 litre one-cylinder high compression ratio SI engine fueled by synthetic producer gas.

The paper describes the optimization of a 50 cc crankcase scavenged two-stroke diesel engine operating on dimethyl ether (DME). The optimization is primarily done with respect to engine efficiency. The underlying idea behind the work is that the low weight, low internal friction and low engine-out NOx of such an engine could make it ideal for future vehicles operating on second-generation biofuels. Data is presented for the performance and emissions at the current state of development of the engine. Brake efficiencies above 30% were obtained despite the small size of the engine. In addition, efficiencies near the maximum were found over a wide operating range of speeds and loads. Maximum bmep is 500 kPa. Results are shown for engine speeds ranging from 2000 to 5000 rpm and loads from idle to full load. At all speeds and loads NOx emissions are below 200 ppm and smokeless operation is achieved. Design improvements relative to an earlier prototype are described.

This work presents the experimental investigation of Diesel Particulate Filter (DPF) regeneration and a calibration procedure of a 1D DPF simulation model based on the commercial software AVL BOOST v. 5.1. Model constants and parameters are fitted on the basis of a number of steady state DPF experiments where the DPF is exposed to real engine exhaust gas in a test bed. The DPF is a silicon carbide filter of the wall flow type without a catalytic coating. A key task concerning the DPF model calibration is to perform accurate DPF experiments because measured gas concentrations, temperatures and soot mass concentrations are used as model boundary conditions. An in-house-developed raw exhaust gas sampling technique is used to measure the soot concentration upstream the DPF which is also needed to find the DPF soot burn rate.

The liquefied natural gas (LNG)-fueled ships were provisioned to meet the strict emission legislation in the marine application since 2000. However, the scientific approach of burning the low-emission natural gas in lean combustion uncovered that the engine suffers from high methane slip emission. Serious questions are raised about the quantity of methane slip during marine conditions when the load varies in multiple frequencies and amplitudes. Previous studies by these authors explained how methane slip increases during load oscillation. This paper examined several practical methods to reach stable combustion in transient conditions to reduce the methane slip. Employing Proportional-Integral-Derivative (PID) controllers in a closed loop, implementing open-loop lookup tables, model predictive controller (MPC), and an innovated solenoid method are performed in a high-fidelity medium-speed natural gas spark-ignition (SI) engine model.

Development of numerical tools for quantitatively assessing biofuel combustion in Internal Combustion Engines and facilitating the identification of optimum operating parameters and emission strategy are challenges of engine combustion research. Biofuels obtained through e.g. a Fischer-Tropsch process (FT) are complex mixtures of wide ranges of high molecular weight hydrocarbons in the diesel and naphtha boiling range dominated by C10-C18 hydrocarbons in n-alkane, iso-alkane, alkenes, aromatic and oxygenate classes. In this paper modeling of combustion in a rapid compression machine has been performed using model compounds from a given FT biofuel distribution as surrogate fuels. Furthermore, the detailed mechanism has been reduced by applying an automatic necessity analysis removing redundant species from the detailed model.

Engine experiments were carried out on a six cylinder DI-diesel engine using synthetic fuel and lubricant containing no PAH (Polycyclic Aromatic Hydrocarbons) [1]. By selectively doping the fuel and oil with pyrene, the effect of fuel and oil originating PAH on the exhaust emissions could be investigated. The experimental results are analyzed in a new way by suggesting a general transport model for PAH. By estimating as many transport quantities as possible it is attempted to gain knowledge about the most dominant mechanisms. The main finding is not surprisingly that for commercial fuels containing substantial concentrations of PAH, the by far major contributor to exhaust PAH is unburned fuel PAH. The concentration of PAH in the oil sump affects only weakly the PAH concentration in the exhaust for engines operating on commercial fuels. The PAH desorbing from the liner are getting burned efficiently, thereby being insignificant.

Engine experiments were carried out in order to investigate the mechanisms involved in connection with the emission of lubricant related polyaromatic hydrocarbons (PAH) from a D.I. diesel engine. In the experiments only the mechanisms related to pyrene emissions were investigated, since synthetic fuels and lubricants containing pyrene as the only aromatic compond were used. Particulate matter (PM) and the soluble organic fraction (SOF) of PM as well as PAH emissions were measured for different engine conditions at different levels of pyrene in the lubricant and the fuel. Possible mechanisms of PAH transportation from the lubricant to the exhaust gas are discussed based on the experimental results, as well as the importance of fuel and lubricant to SOF and PAH emissions.

Due to increasing problems with corrosive wear in marine Diesel Engines, caused by sulphuric acid, it is necessary to understand the mechanism of corrosion. Based on experience with large marine diesel engine operation, a mechanism model is proposed and verified by comparison with practical experience. From operation of engines it is known that the corrosion problem is most severe where the lubrication of the liner is most unsatisfactory. Therefore, most effort is put into modelling the formation and transportation of acid in the lubricant film area. Results from modelling the risk of corrosion during different engine operation conditions are presented.