Modern Diesel Engines Research Articles

Exhaust Gas Recirculation Control based on Artificial Neural Network

In this paper, the new exhaust gas recirculation (EGR) control scheme for Diesel engine is proposed. EGR is so far the most promising approach to reduce in-cylinder NOx formation. The design of EGR control system for modern Diesel engine is based on MAP which is obtained from experiments. The many experiments with different engine speed and loads are necessary. MAP from experiments is not accurate, cannot be used for all the range exactly in case of engine running conditions. Therefore, it is very difficult to design PID controller based on MAP. Moreover, the robust performance cannot be achieved. To overcome these problems, the control scheme based on artificial neural network (ANN) is proposed. This controller has good robust performance and rapid adjustment. From experiments, the system using this controller can achieve good performance.

Effect of soot accumulation in a diesel particle filter on the combustion process and gaseous emissions

Particulate filters are massively used in new diesel vehicles to reduce particulate emissions below the regulation limits. The setting of filters in the exhaust lines imposes various changes in the engine working conditions, including increased back-pressure, resulting in some fuel penalty. In this work, the filter loading process was investigated in a modern common-rail diesel engine equipped with diesel oxidation catalyst and diesel particulate filter. The engine was fuelled with EN-590 diesel fuel and run in a highly emissive operating mode selected among those reproducing the New European Driving Cycle. During the test the intake/exhaust conditions, intake charge, injection and combustion timing, fuel consumption and regulated emissions were measured. It was observed that the EGR (exhaust gas recirculation) ratio decreased from 30% down to 21%, shifting the combustion process away from its design parameters. In consequence, nitrogen oxides emissions increased around 60% along the test, compromising the objectives of the emission regulations. A 4% increase in fuel consumption throughout the test was measured, this value being higher than that expected from previous literature. An energy balance revealed that such penalty was caused by increased pumping losses and, especially, by higher energy losses via exhaust gas temperature and engine coolant.

First Online Measurements of Sulfuric Acid Gas in Modern Heavy-Duty Diesel Engine Exhaust: Implications for Nanoparticle Formation

To mitigate the diesel particle pollution problem, diesel vehicles are fitted with modern exhaust after-treatment systems (ATS), which efficiently remove engine-generated primary particles (soot and ash) and gaseous hydrocarbons. Unfortunately, ATS can promote formation of low-vapor-pressure gases, which may undergo nucleation and condensation leading to formation of nucleation particles (NUP). The chemical nature and formation mechanism of these particles are only poorly explored. Using a novel mass spectrometric method, online measurements of low-vapor-pressure gases were performed for exhaust of a modern heavy-duty diesel engine operated with modern ATS and combusting low and ultralow sulfur fuels and also biofuel. It was observed that the gaseous sulfuric acid (GSA) concentration varied strongly, although engine operation was stable. However, the exhaust GSA was observed to be affected by fuel sulfur level, exhaust after-treatment, and driving conditions. Significant GSA concentrations were measured also when biofuel was used, indicating that GSA can be originated also from lubricant oil sulfur. Furthermore, accompanying NUP measurements and NUP model simulations were performed. We found that the exhaust GSA promotes NUP formation, but also organic (acidic) precursor gases can have a role. The model results indicate that that the measured GSA concentration alone is not high enough to grow the particles to the detected sizes.

The Effect of the Position of Oxygen Group to the Aromatic Ring to Emission Performance in a Heavy-Duty Diesel Engine

In this paper the soot-NOx trade-off and fuel efficiency of various aromatic oxygenates is investigated in a modern DAF heavy-duty diesel engine. All oxygenates were blended to diesel fuel such that the blend oxygen concentration was 2.59 wt.-%. The oxygenates in question, anisole, benzyl alcohol and 2-phenyl ethanol, have similar heating values and cetane numbers, but differ in the position of the functional oxygen group relative to the aromatic ring. The motivation for this study is that in lignin, a widely available and low-cost biomass feedstock, similar aromatic structures are found with varying position of the oxygen group to the aromatic ring. From the results it becomes clear that both the soot-NOx trade-off and the volumetric fuel economy (i.e. ml/kWh) is improved for all oxygenates in all investigated work points. In general, the improvement in the soot-NOx trade-off correlated with the position of the functional oxygen group to the ring, with better overall emission behavior observed as the oxygen group was further from the ring. No distinct trend was observed with respect to fuel economy

다운 스피딩이 NEDC 모드 연비에 미치는 기여도 산출에 관한 연구

Development trend of modern HSDI diesel engine is now focusing on low fuel consumption and emission because of strong interest in global environmental protection. Two big branches of criteria for modern diesel engine development are down sizing and down speeding. Down sizing keeps engine operation condition to the direction of higher load and thus pursuing for better thermal efficiency. But this may cause degraded vehicle dynamic performance because of reduced back up torque. Down speeding keeps engine operation condition to the direction of slightly higher load and lower engine speed. Therefore reduction of back up torque can be limited within flat torque area. This study analyzed fuel economy effect of down speeding on a vehicle powered by HSDI diesel engine in aspect of engine friction work, intake and exhaust pumping work, exhaust hat loss and thermal loss of fuel leakage of fuel injection system. Contribution factor of each engine and vehicle related parameters under basic and down speeding condition were compared and work balance of down speeding during NEDC was analyzed.

Emissions of PCDD/Fs, PCBs, and PAHs from legacy on-road heavy-duty diesel engines

Exhaust emissions of seventeen 2,3,7,8-substituted polychlorinated dibenzo-p-dioxin/furan (PCDD/F) congeners, tetra–octa PCDD/F homologues, 12 WHO 2005 polychlorinated biphenyl (PCB) congeners, mono–nona chlorinated biphenyl homologues, and 19 polycyclic aromatic hydrocarbons (PAHs) from three legacy diesel engines were investigated. The three engines tested were a 1985 model year GM 6.2J-series engine, a 1987 model year Detroit Diesel Corporation 6V92 engine, and a 1993 model year Cummins L10 engine. Results were compared to United States’ mobile source inventory for on-road diesel engines, as well as historic and modern diesel engine emission values. The test fuel contained chlorine at 9.8ppm which is 1.5 orders of magnitude above what is found in current diesel fuel and 3900ppm sulfur to simulate fuels that would have been available when these engines were produced. Results indicate PCDD/F emissions of 13.1, 7.1, and 13.6pg International Toxic Equivalency (I-TEQ)L−1 fuel consumed for the three engines respectively, where non-detects are equal to zero. This compares with a United States’ mobile source on-road diesel engine inventory value of 946pg I-TEQL−1 fuel consumed and 1.28pg I-TEQL−1 fuel consumed for modern engines equipped with a catalyzed diesel particle filter and urea selective catalytic reduction. PCB emissions are 2 orders of magnitude greater than modern diesel engines. PAH results are representative of engines from this era based on historical values and are 3–4 orders of magnitude greater than modern diesel engines.

Comparison of Methods for Online Measurement of Diesel Particulate Matter

Gravimetric analysis is the regulatory method for diesel particulate mass measurement. Because of issues such as adsorption/volatilization artifacts, it faces obstacles in measuring ultra low level emissions from modern diesel engines. Alternative methods of suspended particle mass measurement have been developed that show improvements in time resolution, sensitivity, and accuracy. Three size-resolved methods were considered here. Two methods rely on converting number size distributions obtained using a scanning mobility particle sizer (SMPS). Conversion techniques were based on effective density measurements and the Lall-Friedlander aggregate model. The third method employs the Universal Nanoparticle Analyzer (UNPA) to measure the aggregate size distribution from which mass is calculated. Results were compared with mass concentrations obtained using gravimetric analysis. The effective density conversion resulted in mass concentrations that were highly correlated (R(2) >0.99) with filter mass. The ratios to filter mass concentration were found to be 0.99 ± 0.04, 0.45 ± 0.03, and 0.45 ± 0.19 for the effective density conversion, the Lall-Friedlander conversion, and the UNPA, respectively, for a wide range of engine operating conditions. In addition, the diesel aerosol mass distributions measured by the online techniques are in agreement to within 15-20% with respect to the mass median diameter, while discrepancies were observed in the mass concentration.

Effects of gasoline–diesel and n-butanol–diesel blends on performance and emissions of an automotive direct-injection diesel engine

In the present paper, results of an experimental investigation carried out in a modern diesel engine running at different operating conditions and fuelled with blends of gasoline–diesel and n-butanol–diesel, are reported. The exploration strategy was focused on the management of injection pressure and timing to achieve a condition in which the whole amount of fuel was delivered before ignition. The aim of the paper is to evaluate the effects of fuel blends, which have low cetane number (CN) and are more resistant to auto-ignition than diesel fuel, on performance and engine-out emissions. Blends were mixed by the baseline diesel (D00) with 40% of commercial unleaded gasoline (G40) and 40% of n-butanol (B40). Fuel consumption and engine-out gaseous and smoke emissions from fuel blends were measured and compared to the neat diesel fuel. The investigation was performed on a turbocharged, water-cooled, direct-injection diesel engine, equipped with a common-rail injection system. The engine equipment included an exhaust gas recirculation system controlled by an external driver, a piezo-quartz pressure transducer to detect the in-cylinder pressure signal and a current probe to acquire the energizing current to the injectors. Engine tests were carried out at two engine operating conditions: 2000 r/min at 0.5 MPa and 2500 r/min at 0.8 MPa brake mean effective pressure, exploring the effect of start of injection, O2 concentration at intake and injection pressure on combustion behaviour and engine-out emissions. Taking advantages of the higher resistance of G40 and B40 to auto-ignition, it was possible to extend the range in which a partial premixed combustion was achieved. The management of injection pressure, O2 concentration at intake and injection timing allowed partial premixed combustion to be obtained by extending the ignition delay, both for diesel fuel and blends. The longer ignition delay and the better mixing before combustion made more advanced injection timings, which reduced smoke and nitrogen oxide emissions, possible. The joint effect of higher resistance to auto-ignition and higher volatility of n-butanol and gasoline improved the emissions of the blends compared to the neat diesel fuel, with a low penalty on fuel consumption.

Floating clamping mechanism of PT fuel injector and its dynamic characteristics analysis

PT fuel injector is one of the most important parts of modern diesel engine. To satisfy the requirements of the rapid and accurate test of PT fuel injector, the self-adaptive floating clamping mechanism was developed and used in the relevant bench. Its dynamic characteristics directly influence the test efficiency and accuracy. However, due to its special structure and complex oil pressure signal, related documents for evaluating dynamic characteristics of this mechanism are lack and some dynamic characteristics of this mechanism can’t be extracted and recognized effectively by traditional methods. Aiming at the problem above-mentioned, a new method based on Hilbert-Huang transform (HHT) is presented. Firstly, combining with the actual working process, the dynamic liquid pressure signal of the mechanism is acquired. By analyzing the pressure fluctuation during the whole working process in time domain, oil leakage and hydraulic shock in the clamping chamber are discovered. Secondly, owing to the nonlinearity and nonstationarity of pressure signal, empirical mode decomposition is used, and the signal is decomposed and reconstructed into forced vibration, free vibration and noise. By analyzing forced vibration in the time domain, machining error and installation error of cam are revealed. Finally, free vibration component is analyzed in time-frequency domain with HHT, the traits of free vibration in the time-frequency domain are revealed. Compared with traditional methods, Hilbert spectrum has higher time-frequency resolutions and higher credibility. The improved mechanism based on the above analyses can guarantee the test accuracy of injector injection. This new method based on the analyses of the pressure signal and combined with HHT can provide scientific basis for evaluation, design improvement of the mechanism, and give references for dynamic characteristics analysis of the hydraulic system in the interrelated fields.

Feasibility study for SOFC-GT hybrid locomotive power part II. System packaging and operating route simulation

This work assesses the feasibility of Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT) hybrid power systems for use as the prime mover in freight locomotives. The available space in a diesel engine-powered locomotive is compared to that required for an SOFC-GT system, inclusive of fuel processing systems necessary for the SOFC-GT. The SOFC-GT space requirement is found to be similar to current diesel engines, without consideration of the electrical balance of plant. Preliminary design of the system layout within the locomotive is carried out for illustration. Recent advances in SOFC technology and implications of future improvements are discussed as well. A previously-developed FORTRAN model of an SOFC-GT system is then augmented to simulate the kinematics and power notching of a train and its locomotives. The operation of the SOFC-GT-powered train is investigated along a representative route in Southern California, with simulations presented for diesel reformate as well as natural gas reformate and hydrogen as fuels. Operational parameters and difficulties are explored as are comparisons of expected system performance to modern diesel engines. It is found that even in the diesel case, the SOFC-GT system provides significant savings in fuel and CO2 emissions, making it an attractive option for the rail industry.

Hybrid Cooled Metal Stack Technology (HCMST) for HT PEM fuel cell stack for Combined Heat and Power

High Temp PEM fuel cell technology is very well suited for technology CHP applications. The operating temperature is high enough for the integrated system with a matching reformer to produce high value heat, that can be used for district heating and hot water production. At the same time the high temperature polymer membranes, when operating in the range 160 to 200 degrees C, are very forgiving regarding CO content in the reformate, end this fact makes it possible to design and build a much simpler and cheaper reformer than I the cast for a conventional low temp PEM fuel cell system. However, until now very few robust designs have seen daylight, and the power density of HT PEM fuel cells has been very low. Metacon has developed a novel design, made to provide very high reliability and long life, at the same time as giving high power density. This novel design is founded in the understanding of the real operating conditions of such a fuel cell. It is easy to see that the conditions of a HT PEM fuel cell are very similar to those of an engine for a modern personal car: The temperature is cycled between ambient temperature and around 200 deg C, there are also pressure changes and stresses due to thermal expansion and temperature gradients during start- up and stop. The design developed and patented by Metacon is taking full consequences of these facts. The internal stack cooling is based on pressurized casing, high speed air circulation, and the external cooling uses circulating water, exactly as in a modern diesel engine.

Experimental Studies on the Influence of Diesel Engine Operating Parameters on Properties of Emitted Soot Particles

Physical and chemical properties of emitted soot particles are influenced by diesel engine operating parameters. In order to find correlations between the in-cylinder processes of combustion and the engine-out properties of soot particles, parameter studies were carried out on a modern light duty production diesel engine (turbo direct injection, TDI) and an optically accessed single cylinder diesel engine (single cylinder). Several techniques have been combined to analyze the combustion process as well as the emitted particles. The size of emitted soot particles of the TDI engine has been determined by a scanning mobility particle sizer (SMPS), and soot samples have been analyzed by a high-resolution transmission electron microscope (HR-TEM) and by thermogravimetry (TG). In addition, the internal combustion in an optically accessed single cylinder engine has been observed by time resolved spectroscopy as well as OH*- and C2-imaging. It turns out that in both cases, increasing injection pressure leads to a decreasing soot particle agglomerate and primary particle size with decreasing oxidation temperature.

Performance and emissions of a Euro5 small diesel engine fuelled with biodiesel

This article describes the effects of using neat biodiesel on a modern small displacement passenger car diesel engine, highlighting the need for a specific adjusted electronic control unit (ECU) calibration for biodiesel. Engine performance were evaluated at full load with a standard ECU calibration as well as with an ECU calibration specifically adjusted for biodiesel; Break Specific Fuel Consumption (BSFC) and exhaust emissions was then evaluated at seven part load operating conditions, representative of the New European Driving Cycle (NEDC). Tests showed that through recalibration it is possible to obtain the same performance measured under diesel operation, with benefits in terms of engine-out emissions, especially as far as smoke emissions are concerned. Moreover, particle number and size distribution at engine outlet were also evaluated at part load operating conditions, showing a significant reduction of particle number and mass with biodiesel.

MD2-4 Application of the Optical Connectivity Method to a Real Size Heavy Duty CIDI-Injector : Application of the Optical Connectivity Method(MD: Measurement and Diagnostics,General Session Papers)

Injection systems of modern diesel engines are the key to increase the fuel efficiency and to lower pollutant emissions. Therefore, a detailed understanding of the spray generated by the injector nozzle is crucial to optimize the process of the mixture formation and thus the combustion process. Up to now, the spray behavior in the near nozzle field is not completely understood. Standard optical diagnostic methods are known to fail visualizing the near nozzle region due to the high optical density of the diesel spray. One approach to address this challenge is the optical connectivity method, described by Charalampous et al.. It can be used to measure the length of the continuous liquid jet core in sprays. Here, the laser light is directed through the injection nozzle to illuminate the liquid jet internally. The spray breakup interrupts a further light transfer and thus limits the illuminated area to the liquid core. While so far a specially designed injector was necessary, in this work a new approach is invented where the laser light is guided by an optical fiber into the sack hole through one of the injector holes of an unmodified stock injector. The feasibility of this approach is demonstrated on a heavy duty diesel injector with fuel pressures up to 80 MPa, being adapted to the large high pressure injection chamber of the Institute of Technical Combustion in Hannover. Other than in, no additional tracer fuel was necessary, as the direct stray light yielded enough signal intensity. First results of the transient behavior of the liquid core length are discussed.

Diesel vehicles and sustainable mobility in the U.S.

Concerns regarding global warming and energy security have increased the importance of decreasing emissions of CO2 from vehicles. Diesel vehicles have higher fuel economy and lower CO2 emissions than their gasoline counterparts. On a well-to-wheels per vehicle per km basis it has been estimated that diesel light-duty vehicles in 2015 will emit 14–27% less CO2 than their gasoline counterparts. We estimate here that on a gCO2/kWh at peak torque, diesel medium-duty vehicles currently have an approximately 10% CO2 advantage over their gasoline counterparts. At light and moderate loads the CO2 advantage for medium-duty diesels with SCR after-treatment will be greater than 10% (reflecting pumping losses when gasoline engines are operated at low and moderate loads). Emission of NOx, HCs, and PM from diesel (and gasoline) vehicles has decreased substantially over the past decade and further reductions are anticipated in the future. In addition to the heavy-duty segment, which diesels currently dominate, modern diesel engines are likely to continue to play an important role in the medium-duty segment, and perhaps also in the light-duty segment in a transition to more sustainable mobility.

Feasibility study of the potential use of chemistry based emission predictions for real-time control of modern diesel engines

The feasibility of using chemical kinetics-based prediction of emission species for real-time control of modern diesel engines is investigated. A previously developed fast, physics-based model is used as a representative example. The temporal variation of temperature required for the computation of the reaction rate constants is obtained from the solution of the energy equation. The effects of composition and temperature on the thermo-physical properties of the working fluid are included in the computations. Issues relating to model complexity, computation time, and fidelity are discussed in the context of both equilibrium and finite rate chemistry for use in the real time environment. The set of model inputs and tunable parameters is assessed for real-time use against the standard sensor set available on modern diesel engines. Results show that use of physics-based quasi-dimensional models is promising but may need complex variable mappings for real-time application.

New Indicated Mean Effective Pressure (IMEP) model for predicting crankshaft movement

Indicated Mean Effective Pressure models (IMEP) are essential to estimate the indicated torque in internal combustion engine; they also provide important information about the mechanical efficiency of the engine thermodynamic cycle which describes the conversion of the fuel combustion energy into mechanical work. In the past, many researches were made to improve the IMEP prediction and measurement techniques at different engine operating conditions. In this paper, we proposed a detailed IMEP model which separately describes the IMEP-Low pressure and the IMEP-High pressure of a modern diesel engine; the IMEP is the direct subtraction result between these two variables. We firstly studied the evolution of the IMEP HP and IMEP LP with respect to the engine’s variables and then we deduced the variables of influence and the form of the equations that can be used to develop the models. Finally, the models’ coefficients were determined based on experimental data collected on a steady state test bench and using the least square regression method. In addition, the IMEP HP model results were compared to transient experimental data collected on a chassis dynamometer test bench; the model results are in excellent agreement with the experimental data.

Effect of intake valve closure modulation on effective compression ratio and gas exchange in turbocharged multi-cylinder engines utilizing EGR

Advanced combustion strategies including premixed charge compression ignition, homogeneous charge compression ignition, and lifted flame combustion are promising approaches for meeting increasingly stringent emissions regulations and improving fuel efficiency in next generation powertrains. Variable valve actuation and closed-loop control promise to play a key role in the promotion and control of these advanced combustion modes. For example, modulation of intake valve closure timing dictates the effective compression ratio and influences the total amount of charge trapped inside the cylinder, and in so doing allows manipulation of the in-cylinder reactant concentrations and temperature prior to and during the combustion process. The effort described here uses data from, and an experimentally-validated simulation model for, a multi-cylinder engine with variable geometry turbocharging, cooled exhaust gas recirculation, and fully flexible variable valve actuation. This effort’s intent is to determine the control authority over the gas exchange process and effective compression ratio when intake valve closure timing modulation is included on a modern turbocharged diesel engine, as well as to lay the groundwork for closed-loop control design for the promotion and control of advanced combustion modes. The engine testbed at Purdue provides a unique opportunity to pursue these objectives for turbocharged engines with exhaust gas recirculation, as it is the only such engine system in academia outfitted with multi-cylinder fully-flexible valve actuation. A method to estimate in-cylinder temperature at top dead centre is also described. Candidate control architectures for both steady state and transient operation are introduced.

Soot Modeling for Advanced Control of Diesel Engine Aftertreatment

Diesel particulate filters (DPFs) are well assessed aftertreatment devices, equipping almost every modern diesel engine on the market to comply with today’s stringent emission standards. However, an accurate estimation of soot loading, which is instrumental to ensuring optimal performance of the whole engine-after-treatment assembly, is still a major challenge. In fact, several highly coupled physical-chemical phenomena occur at the same time, and a vast number of engine and exhaust dependent parameters make this task even more daunting. This challenge may be solved with models characterized by different degrees of detail (0-D to 3-D) depending on the specific application. However, the use of real-time, but accurate enough models, may be the primary hurdle that has to be overcome when confronted with advanced exhaust emissions control challenges, such as the integration of the DPF with the engine or other critical aftertreatment components (selective catalytic reduction or other NOx control components), or to properly develop model-based OBD sensors. This paper aims at addressing real time DPF modeling issues with special regard to key parameter settings, by using the 1-D code called ExhAUST (exhaust aftertreatment unified simulation tool), which was jointly developed by the University of Rome Tor Vergata and West Virginia University. ExhAUST is characterized by a novel and unique full analytical treatment of the wall that allows a highly detailed representation of the soot loading evolution inside the DPF porous matrix. Numerical results are compared with experimental data gathered at West Virginia University engine laboratory using a MY2004 Mack®MP7-355E, an 11 liter, 6-cylinder, inline heavy-duty diesel engine coupled to a Johnson Matthey CCRT diesel oxidation catalyst + CDPF, catalyzed DPF exhaust aftertreatment system. To that aim, the engine test bench was equipped with a DPF weighing system to track soot loading over a specifically developed engine operating procedure. Results indicate that the model is accurate enough to capture soot loading and back pressure histories with regard to different steady state engine operating points, without a need for any tuning procedure of the key parameters. Thus, the use of ExhAUST for application to advanced after-treatment control appears to be a promising tool at this stage.

Effect of different nozzle geometries using Pure Rapeseed Oil in a modern Diesel engine on combustion and exhaust emissions

Effect of different nozzle geometries using Pure Rapeseed Oil in a modern Diesel engine on combustion and exhaust emissions