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Journal Article

A Fast Crank Angle Resolved Zero-Dimensional NOx Model Implemented on a Field-Programmable Gate Array

2013-04-08
2013-01-0344
In the automotive industry, the piezo-based in-cylinder pressure sensor is getting commercialized and used in production vehicles. For example, the pressure sensor offers the opportunity to design algorithms for estimation of engine emissions, such as soot and NO , during a combustion cycle. In this paper a zero-dimensional NO model for a diesel engine is implemented that will be used in real time. The model is based on the thermal NO formation and the Zeldovich mechanism using two non-geometrical zones: burned and unburned zone. The influence of EGR on combustion temperature was modeled using a well-known thermodynamic identity where specific heat at constant pressure is included. Specific heat will vary with temperature and the gas composition. The model was implemented in LabVIEW using tools specific for an FPGA (Field-Programmable Gate Array).
Technical Paper

Swirl and Injection Pressure Impact on After-Oxidation in Diesel Combustion, Examined with Simultaneous Combustion Image Velocimetry and Two Colour Optical Method

2013-04-08
2013-01-0913
After-oxidation in Heavy Duty (HD) diesel combustion is of paramount importance for emissions out from the engine. During diffusion diesel combustion, lots of particulate matter (PM) is created. Most of the PM are combusted during the after-oxidation part of the combustion. Still some of the PM is not, especially during an engine transient at low lambda. To enhance the PM oxidation in the late engine cycle, swirl together with high injection pressure can be implemented to increase in-cylinder turbulence at different stages in the cycle. Historically swirl is known to reduce soot particulates. It has also been shown, that with today's high injection pressures, can be combined with swirl to reduce PM at an, for example, engine transient. The mechanism why the PM engine out is reduced also at high injection pressures is however not so well understood.
Technical Paper

Radiocarbon and Hydrocarbon Analysis of PM Sources During WHTC Tests on a Biodiesel-Fueled Engine

2014-04-01
2014-01-1243
PM in diesel exhaust has been given much attention due to its adverse effect on both climate and health. As the PM emission levels are tightened, the portion of particles originating from the lubrication oil is likely to increase. In this study, exhausts from a biodiesel-fueled Euro 5 engine were examined to determine how much of the carbonaceous particles that originated from the fuel and the lubrication oil, respectively. A combination of three methods was used to determine the PM origin: chain length analysis of the hydrocarbons, determination of organic and elemental carbon (OC and EC), and the concentration of 14C found in the exhausts. It was found that the standard method for measuring hydrocarbons in PM on a filter (chain length analysis) only accounted for 63 % of the OC, meaning that it did not account for all non-soot carbon in the exhausts.
Technical Paper

A Study on In-Cycle Control of NOx Using Injection Strategy with a Fast Cylinder Pressure Based Emission Model as Feedback

2013-10-14
2013-01-2603
The emission control in heavy-duty vehicles today is based on predefined injection strategies and after-treatment systems such as SCR (selective catalytic reduction) and DPF (diesel particulate filter). State-of-the-art engine control is presently based on cycle-to-cycle resolution. The introduction of the crank angle resolved pressure measurement, from a piezo-based pressure sensor, enables the possibility to control the fuel injection based on combustion feedback while the combustion is occurring. In this paper a study is presented on the possibility to control NOx (nitrogen oxides) formation with a crank angle resolved NOx estimator as feedback. The estimator and the injection control are implemented on an FPGA (Field-Programmable Gate Array) to manage the inherent time constraints. The FPGA is integrated with the rest of the engine control system for injection control and measurement.
Technical Paper

Swirl and Injection Pressure Effect on Post-Oxidation Flow Pattern Evaluated with Combustion Image Velocimetry, CIV, and CFD Simulation

2013-10-14
2013-01-2577
In-cylinder flow pattern has been examined experimentally in a heavy duty optical diesel engine and simulated with CFD code during the combustion and the post-oxidation phase. Mean swirling velocity field and its evolution were extracted from optical tests with combustion image velocimetry (CIV). It is known that the post-oxidation period has great impact on the soot emissions. Lately it has been shown in swirling combustion systems with high injection pressures, that the remaining swirling vortex in the post-oxidation phase deviates strongly from solid body rotation. Solid body rotation can only be assumed to be the case before fuel injection. In the studied cases the tangential velocity is higher in the centre of the piston bowl compared to the outer region of the bowl. The used CIV method is closely related to the PIV technique, but makes it possible to extract flow pattern during combustion at full load in an optical diesel engine.
Technical Paper

A Study of In-Cylinder Fuel Spray Formation and its Influence on Exhaust Emissions Using an Optical Diesel Engine

2010-05-05
2010-01-1498
Increasingly stringent emission legislation as well as increased demand on fuel efficiency calls for further research and development in the diesel engine field. Spray formation, evaporation and ignition delay are important factors that influence the combustion and emission formation processes in a diesel engine. Increased understanding of the mixture formation process is valuable in the development of low emission, high efficiency diesel engines. In this paper spray formation and ignition under real engine conditions have been studied in an optical engine capable of running close to full load for a real HD diesel engine. Powerful external lights were used to provide the required light intensity for high speed camera images in the combustion chamber prior to ignition. A specially developed software was used for spray edge detection and tracking. The software provides crank angle resolved spray penetration data.
Technical Paper

Study of a Heavy Duty Euro5 EGR-Engine Sensitivity to Fuel Change with Emphasis on Combustion and Emission Formation

2010-04-12
2010-01-0872
A diesel engine developed for an international market must be able to run on different fuels considering the diesel fuel qualities and the increasing selection of biofuels in the world. This leads to the question of how different fuels perform relative to a standard diesel fuel when not changing the hardware settings. In this study five fuels (Japanese diesel, MK3, EN590 with 10% RME, EN590 with 30% RME and pure RME) have been compared to a reference diesel fuel (Swedish MK1) when run on three different speeds and three different loads at each speed. The experiments are run on a Scania 13l Euro5 engine with standard settings for Swedish MK1 diesel. In general the differences were not large between the fuels. NO x usually increased compared to MK1 and then soot decreased as would be expected. The combustion efficiency increased with increased RME contents of the fuel but the indicated efficiency was not influenced by RME except for at higher loads.
Journal Article

Towards a Model for Engine Oil Hydrocarbon Particulate Matter

2010-10-25
2010-01-2098
The drive to reduce particle emissions from heavy-duty diesel engines has reached the stage where the contribution from the lubricant can have a major impact on the total amount of particulate matter (PM). This paper proposes a model to predict the survival rate (unburnt oil divided by oil consumption) of the hydrocarbons from the lubricant consumed in the cylinder. The input data are oil consumption and cylinder temperature versus crank angle. The proposed model was tuned to correlate well with data from a six-cylinder heavy-duty diesel engine that meets the Euro 5 legislation without exhaust gas aftertreatment. The measured (and modelled) oil survival shows a strong correlation with engine power. The maximum oil survival rate measured (19%) was at motoring conditions at high speed. For this engine, loads above 100 kW yielded an oil survival rate of nearly zero.
Journal Article

Sensitivity Analysis Study on Ethanol Partially Premixed Combustion

2013-04-08
2013-01-0269
Partially Premixed Combustion (PPC) is a combustion concept which aims to provide combustion with low smoke and NOx with high thermal efficiency. Extending the ignition delay to enhance the premixing, avoiding spray-driven combustion and controlling the combustion temperature at an optimum level through use of suitable lambda and EGR levels have been recognized as key factors to achieve such a combustion. Fuels with high ignitability resistance have been proven to be a useful to extend the ignition delay. In this work pure ethanol has been used as a PPC fuel. The objective of this research was initially to investigate the required operating conditions for PPC with ethanol. Additionally, a sensitivity analysis was performed to understand how the required parameters for ethanol PPC such as lambda, EGR rate, injection pressure and inlet temperature influence the combustion in terms of controllability, stability, emissions (i.e.
Journal Article

An In-Cycle based NOx Reduction Strategy using Direct Injection of AdBlue

2014-10-13
2014-01-2817
In the last couple of decades, countries have enacted new laws concerning environmental pollution caused by heavy-duty commercial and passenger vehicles. This is done mainly in an effort to reduce smog and health impacts caused by the different pollutions. One of the legislated pollutions, among a wide range of regulated pollutions, is nitrogen oxides (commonly abbreviated as NOx). The SCR (Selective Catalytic Reduction) was introduced in the automotive industry to reduce NOx emissions leaving the vehicle. The basic idea is to inject a urea solution (AdBlue™) in the exhaust gas before the gas enters the catalyst. The optimal working temperature for the catalyst is somewhere in the range of 300 to 400 °C. For the reactions to occur without a catalyst, the gas temperature has to be at least 800 °C. These temperatures only occur in the engine cylinder itself, during and after the combustion.
Technical Paper

Modeling the Intake CO2-level during Load Transients on a 1-Cylinder Heavy Duty DI Diesel Engine

2009-09-13
2009-24-0039
For diesel engines the major exhaust problem is particulate matter and NOx emissions. To reduce NOx, exhaust gas recirculation (EGR) is often used. The behavior of the EGR-level will therefore influence the emissions and it is therefore valuable to keep track of the EGR-level. Especially during transients it is difficult to predict how the EGR-level varies. In this paper the CO2-level in the intake is modeled on a 1-cylinder diesel engine to predict the in cylinder behavior during transients. The model is based on simple thermodynamics together with the ideal gas law. Using this, the model is validated by experimental data during transients and the correlation between model and experiment is shown to be strong. Furthermore, the total tank volume is decreased to achieve a faster mixing with the intention of simulating the behavior of the CO2-level in a full-size engine which has a higher gas flow.
Technical Paper

Turbocharger Speed Estimation via Vibration Analysis

2016-04-05
2016-01-0632
Due to demanding legislation on exhaust emissions for internal combustion engines and increasing fuel prices, automotive manufacturers have focused their efforts on optimizing turbocharging systems. Turbocharger system control optimization is difficult: Unsteady flow conditions combined with not very accurate compressor maps make the real time turbocharger rotational speed one of the most important quantities in the optimization process. This work presents a methodology designed to obtain the turbocharger rotational speed via vibration analysis. Standard knock sensors have been employed in order to achieve a robust and accurate, yet still a low-cost solution capable of being mounted on-board. Results show that the developed method gives an estimation of the turbocharger rotational speed, with errors and accuracy acceptable for the proposed application. The method has been evaluated on a heavy duty diesel engine.
Technical Paper

Analysis of Soot Particles in the Cylinder of a Heavy Duty Diesel Engine with High EGR

2015-09-06
2015-24-2448
When applying high amount of EGR (exhaust gas recirculation) in Partially Premixed Combustion (PPC) using diesel fuel, an increase in soot emission is observed as a penalty. To better understand how EGR affects soot particles in the cylinder, a fast gas sampling technique was used to draw gas samples directly out of the combustion chamber in a Scania D13 heavy duty diesel engine. The samples were characterized on-line using a scanning mobility particle sizer for soot size distributions and an aethalometer for black carbon (soot) mass concentrations. Three EGR rates, 0%, 56% and 64% were applied in the study. It was found that EGR reduces both the soot formation rate and the soot oxidation rate, due to lower flame temperature and a lower availability of oxidizing agents. With higher EGR rates, the peak soot mass concentration decreased. However, the oxidation rate was reduced even more.
Technical Paper

The Application of Ceramic and Catalytic Coatings to Reduce the Unburned Hydrocarbon Emissions from a Homogeneous Charge Compression Ignition Engine

2000-06-19
2000-01-1833
An experimental and theoretical study of the effect of thermal barriers and catalytic coatings in a Homogeneous Charge Compression Ignition (HCCI) engine has been conducted. The main intent of the study was to investigate if a thermal barrier or catalytic coating of the wall would support the oxidation of the near-wall unburned hydrocarbons. In addition, the effect of these coatings on thermal efficiency due to changed heat transfer characteristics was investigated. The experimental setup was based on a partially coated combustion chamber. The upper part of the cylinder liner, the piston top including the top land, the valves and the cylinder head were all coated. As a thermal barrier, a coating based on plasma-sprayed Al2O3 was used. The catalytic coating was based on plasma-sprayed ZrO2 doped with Platinum. The two coatings tested were of varying thickness' of 0.15, 0.25 and 0.6 mm. The compression ratio was set to 16.75:1.
Technical Paper

CFD Studies of Combustion and In-Cylinder Soot Trends in a DI Diesel Engine - Comparison to Direct Photography Studies

2000-06-19
2000-01-1889
The main objective of this work is to develop a CFD model for studies of combustion and in-cylinder soot trends in a single cylinder DI diesel engine based on the Scania 14 liter V8 engine. The evaluation of the model is made with respect to ignition, cylinder pressure, heat release, onset of diffusion controlled combustion, liquid fuel spray penetration, in-cylinder soot distribution and exhaust soot level. The simulation results are compared to direct photography images and two-color calculations of temperature and soot distribution in a corresponding optical access test engine. This comparison shows good agreement concerning diffusion flame onset, liquid penetration, rate of heat release and local temperature distribution. Moreover, the prediction of in-cylinder soot distribution after end of injection also agrees well with the two-color calculation. To validate the model, the simulation is repeated for three different sets of operating conditions.
Technical Paper

Future Fuels for DISI Engines: A Review on Oxygenated, Liquid Biofuels

2019-01-15
2019-01-0036
Global warming and climate change have led to a greater interest in the implementation of biofuels in internal combustion engines. In spark ignited engines, biofuels have been shown to improve efficiency and knock resistance while decreasing emissions of unburned hydrocarbons, carbon monoxide and particles. This study investigates the effect of biofuels on SI engine combustion through a graphical compilation of previously reported results. Experimental data from 88 articles were used to evaluate the trends of the addition of different biofuels in gasoline. Graphs illustrating engine performance, combustion phasing and emissions are presented in conjunction with data on the physiochemical properties of each biofuel component to understand the observed trends. Internal combustion engines have the ability to handle a wide variety of fuels resulting in a broad range of biofuel candidates.
Technical Paper

Knock Sensor Based Virtual Cylinder Pressure Sensor

2019-01-15
2019-01-0040
Typically the combustion in a direct injected compression ignited internal combustion engine is open-loop controlled. The introduction of a cylinder pressure sensor opens up the possibility of a virtual combustion sensor which could enable closed-loop combustion control and thus the potential to counteract effects such as engine part to part variation, component ageing and fuel quality diversity. Closed-loop combustion control requires precise, robust and preferably cheap sensors. This paper presents a virtual cylinder pressure sensor based on the signal from the inexpensive but well proven knock sensor. The method used to convert the knock sensor signal into a pressure estimate included the stages: Phase correcting the raw signal, Filtering the raw signal, Scaling the signal to known thermodynamic laws and provided engine sensors signals and Reconstructing parts of the signal with other known models and assumptions.
Technical Paper

Particle Emission Measurements in a SI CNG Engine Using Oils with Controlled Ash Content

2019-01-15
2019-01-0053
Clean combustion is one of the inherent benefits of using a high methane content fuel, natural gas or biogas. A single carbon atom in the fuel molecule results, to a large extent, in particle-free combustion. This is due to the high energy required for binding multiple carbon atoms together during the combustion process, required to form soot particles. When scaling up this process and applying it in the internal combustion engine, the resulting emissions from the engine have not been observed to be as particle free as the theory on methane combustion indicates. These particles stem from the combustion of engine oil and its ash content. One common practice has been to lower the ash content to regulate the particulate emissions, as was done for diesel engines. For a gas engine, this approach has been difficult to apply, as the piston and valvetrain lubrication becomes insufficient.
Technical Paper

Agglomeration and Nucleation of Non-Volatile Particles in a Particle Grouping Exhaust Pipe of a Euro VI Heavy-Duty Diesel Engine

2019-01-15
2019-01-0044
The possibility of non-volatile particle agglomeration in engine exhaust was experimentally examined in a Euro VI heavy duty engine using a variable cross section agglomeration pipe, insulated and double walled for minimal thermophoresis. The agglomeration pipe was located between the turbocharger and the exhaust treatment devices. Sampling was made across the pipe and along the centre-line of the agglomeration pipe. The performance of the agglomeration pipe was compared with an equivalent insulated straight pipe. The non-volatile total particle number and size distribution were investigated. Particle number measurements were conducted according to the guidelines from the Particle Measurement Programme. The Engine was fuelled with commercially available low sulphur S10 diesel.
Technical Paper

Experimental Determination of the Heat Transfer Coefficient in Piston Cooling Galleries

2018-09-10
2018-01-1776
Piston cooling galleries are critical for the pistons’ capability to handle increasing power density while maintaining the same level of durability. However, piston cooling also accounts for a considerable amount of heat rejection and parasitic losses. Knowing the distribution of the heat transfer coefficient (HTC) inside the cooling gallery could enable new designs which ensure effective cooling of areas decisive for durability while minimizing parasitic losses and overall heat rejection. In this study, an inverse heat transfer method is presented to determine the spatial HTC distribution inside the cooling gallery based on surface temperature measurements with an infrared (IR) camera. The method utilizes a piston specially machined so it only has a thin sheet of material of a known thickness left between the cooling gallery and the piston bowl. The piston - initially at room temperature - is heated up with warm oil injected into the cooling gallery.
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