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Technical Paper

Effect of Diamond-Like Carbon Coating on Anti-Scuffing Characteristics of Piston Pins

2019-04-02
2019-01-0184
It has been proposed that downspeeding combined with high boost levels would effectively reduce fuel consumption in heavy-duty diesel engines. Under low-speed and high-boost operating conditions, however, the in-cylinder gas pressure, which acts on the piston crown, is greater than the piston inertia force (such that there is no force reversal), over the entire range of crank angles. Therefore, the piston pin never lifts away from the main loading area (the bottom) of the connecting rod small-end bushing where the contact pressure against the piston pin is highest. In such operating conditions, lubricant starvation is easily induced at the interface between the piston pin and small-end bushing. Through carefully devised engine tests, the authors confirmed that the piston pin scuffing phenomenon arises when the boost pressure exceeds a critical value at which the no-force reversal condition appears.
Technical Paper

Kinetic Modeling of Ammonia-SCR and Experimental Studies over Monolithic Cu-ZSM-5 Catalyst

2019-01-15
2019-01-0024
Ammonia-selective catalytic reduction (SCR) systems have been introduced commercially in diesel vehicles, however catalyst systems with higher conversion efficiency and better control characteristics are required to know the actual emissions during operation and the emissions in random test cycles. Computational fluid dynamics (CFD) is an effective approach when applied to SCR catalyst development, and many models have been proposed, but these models need experimental verification and are limited in the situations they apply to. Further, taking account of redox cycle is important to have better accuracy in transient operation, however there are few models considering the cycle. Model development considering the redox reactions in a zeolite catalyst, Cu-ZSM-5, is the object of the research here, and the effects of exhaust gas composition on the SCR reaction and NH3 oxidation at high temperatures are investigated.
Technical Paper

Phenomenological Modeling and Experiments to Investigate the Combined Effects of High Pressure and Multiple Injection Strategies with EGR on Combustion and Emission Characteristics of a CRDI Diesel Engine

2019-01-15
2019-01-0056
Nowadays, due to stringent emission regulations, it is imperative to incorporate modeling efforts with experiments. This paper presents the development of a phenomenological model to investigate the effects of various in-cylinder strategies on combustion and emission characteristics of a common-rail direct-injection (CRDI) diesel engine. Experiments were conducted on a single-cylinder, supercharged engine with displacement volume of 0.55 l at different operating conditions with various combinations of injection pressure, number of injections involving single injection and multiple injections with two injection pulses, and EGR. Data obtained from experiments was also used for model validation. The model incorporated detailed phenomenological aspects of spray growth, air entrainment, droplet evaporation, wall impingement, ignition delay, premixed and mixing-controlled combustion rates, and emissions of nitrogen oxides (NOx) and diesel soot.
Technical Paper

Oxidative Deterioration Properties of FAME-Blended Diesel Fuel

2018-04-03
2018-01-0924
The correlation between newly approved EN 15751 and the internal diesel injector deposits (IDID) due to fuel oxidative deterioration has not been made clear. In the present research, the Rancimat method was slightly modified to research the relationship between fuel oxidative deterioration and the deterioration products generated from the fuel. After heating fuel at 120 to 150°C for a set period, insoluble deterioration products (IDID-like substances) were generated and their weights were measured. At the same time, the shifts of the conductivity in trap water were analyzed from a new perspective, and its relationship with the deterioration products was investigated. At 120°C and 130°C, conductivity rising rates after the inflection point (this set of data represents the rate of organic acid generation in the fuel, and we named “Oxidation rate”) exhibited a strong correlation with the quantity of deterioration products.
Journal Article

Chemical Reaction Processes of Fuel Reformation by Diesel Engine Piston Compression of Rich Homogeneous Air-Fuel Mixture

2017-11-15
2017-32-0120
To extend the operational range of premixed diesel combustion, fuel reformation by piston induced compression of rich homogeneous air-fuel mixtures was conducted in this study. Reformed gas compositions and chemical processes were first simulated with the chemistry dynamics simulation, CHEMKIN Pro, by changing the intake oxygen content, intake air temperature, and compression ratio. A single cylinder diesel engine was utilized to verify the simulation results. With the simulation and experiments, the characteristics of the reformed gas with respect to the reformer cylinder operating condition were obtained. Further, the thermal decomposition and partial oxidation reaction mechanisms of the fuel in extremely low oxygen concentrations were obtained with the characteristics of the gas production at the various reaction temperatures.
Technical Paper

Development of CNG/Diesel Dual-Compatible Engine Oil for Heavy-Duty Trucks in Thailand

2017-10-08
2017-01-2350
In Thailand, most heavy-duty trucks were equipped with diesel engine, while a small portion was equipped with compressed natural gas (CNG) engine. However, in the past few years the number of CNG fuel trucks in Thailand has increased significantly due to the cheaper cost of CNG. In general, the emphasis of heavy-duty diesel engine oil performance is on piston cleanliness and soot handling properties, while thermal and anti-oxidation properties are most critical for CNG engine oil performance. For truck fleet owners who operate both types of trucks, using the inappropriate oil that is not fit-for-purpose can adversely affect engine performance and reduce engine service lifespan under prolonged usage. A novel CNG/diesel engine oil was developed to meet both JASO DH-2 heavy-duty diesel engine oil performance and CNG engine oil performance. The candidate formulation was proved adequately fit for practical use regarding to thermal and anti-oxidation properties.
Technical Paper

Impingement and Adhesion on Cylinder Liners with Post Diesel Fuel Injections

2016-10-17
2016-01-2193
Diesel particulate filters (DPF) are widely used in diesel engines, and forced regeneration is necessary to remove particulate matter (PM) accumulating on the DPF. This may be achieved with fuel injected after the main combustion is complete, the socalled “post fuel injection”, and supplied to the diesel oxidation catalyst (DOC) upstream of the DPF. This increases the exhaust gas temperature in the DOC and the DPF is regenerated with the high temperature gas flow. In most cases, the post fuel injection takes place at 30-90CA ATDC, and fuel may impinge on and adhere to the cylinder liner wall in some cases. Buddie and Pischinger [1] have reported a lubricant oil dilution with the post fuel injection by engine tests and simulations, and adhering fuel is a cause of worsening fuel consumption. In this paper, the impingement and adhesion of post diesel fuel injections on the cylinder liner was investigated by an optical method with a high pressure constant volume chamber (ϕ110mm, 883cm3).
Technical Paper

Performance Improvements in a Natural Gas Dual Fuel Compression Ignition Engine with 250 MPa Pilot Injection of Diesel Fuel as an Ignition Source

2016-10-17
2016-01-2306
The engine performance and the exhaust gas emissions in a dual fuel compression ignition engine with natural gas as the main fuel and a small quantity of pilot injection of diesel fuel with the ultra-high injection pressure of 250 MPa as an ignition source were investigated at 0.3 MPa and 0.8 MPa IMEP. With increasing injection pressure the unburned loss decreases and the thermal efficiency improves at both IMEP conditions. At the 0.3 MPa IMEP the THC and CO emissions are significantly reduced when maintaining the equivalence ratio of natural gas with decreasing the volumetric efficiency by intake gas throttling, but the NOx emissions increase and excessive intake gas throttling results in a decrease in the indicated thermal efficiency. Under the 250 MPa pilot injection condition simultaneous reductions in the NOx, THC, and CO emissions can be established with maintaining the equivalence ratio of natural gas by intake gas throttling.
Technical Paper

A Study on the Effects of a Higher Compression Ratio in the Combustion Chamber on Diesel Engine Performance

2016-04-05
2016-01-0722
In order to improve the brake thermal efficiency of the engine, such as cooling and friction losses from the theoretical thermal efficiency, it is necessary to minimize various losses. However, it is also essential to consider improvements in theoretical thermal efficiency along with the reduction of the various losses. In an effort to improve the brake thermal efficiency of heavy-duty diesel engines used in commercial vehicles, this research focused on two important factors leading to the engine's theoretical thermal efficiency: the compression ratio and the specific heat ratio. Based on the results of theoretical thermodynamic cycle analyses for the effects of the above two factors, it was predicted that raising the compression ratio from a base engine specification of 17 to 26, and increasing the specific heat ratio would lead to a significant increase in theoretical thermal efficiency.
Technical Paper

Characterization of Emissions from Urea-SCR and DPF System for Heavy Duty Engine

2015-09-01
2015-01-2016
Urea selective catalyst reduction (SCR) systems have a high NOx conversion rate because the ammonia formed by the hydrolyzing urea solution reacts with NOx efficiently as a reducing agent. Systems combining urea-SCR and a diesel particulate filter (DPF) have been adopted in heavy duty vehicles to meet the post new long term emissions regulations in Japan. This study examined the emissions reduction performance of these systems after 160,000 km. The emissions that were examined included both regulated emissions (NOx, PM, HC, and CO) and unregulated emissions. As a result, the cleanness of diesel emissions from a urea-SCR and DPF system was confirmed.
Technical Paper

Influence of Fuel Volatility on Evaporation Characteristics of Diesel Sprays in Various Low Temperature and Low Density Surrounding Conditions Like at Early Pilot or Late Post Injections

2015-09-01
2015-01-1923
The diesel spray characteristics in early pilot and late post fuel injections in a constant volume chamber which can create the in-cylinder conditions of a diesel engine were visualized with high speed video. At the early pilot and late post fuel injection, there was a longer penetration of the liquid phase fuel spray as well as slower evaporation. With normal heptane the impingement of liquid spray with early pilot and post fuel injections can be avoided due to a faster evaporation. The penetration of liquid phase fuel spray increases significantly at low IMEP and late post injection conditions with diesel fuel.
Technical Paper

Development of Fuel Economy Engine Oil for Heavy Duty Diesel Engine

2015-09-01
2015-01-2034
More stringent emissions regulations, fuel economy standards, and regulations are currently being discussed to help reduce both CO2 and exhaust emissions. Vehicle manufacturers have been developing new engine technologies, such as downsizing and down-speeding with reduced friction loss, improved engine combustion and efficiency, heat loss recycling, power-train friction loss recycling, and reduced power-train friction loss. The use of more efficient fuel economy 5W-30 engine oils for heavy duty commercial vehicles has started to expand since 2009 in Japan as one technological solution to help reduce CO2 emissions. However, fuel economy 5W-30 oils for use in heavy duty vehicles in Europe are mainly based on synthetic oils, which are much expensive than the mineral oils that are predominantly used in Japan.
Journal Article

Molecular Structure of Hydrocarbons and Auto-Ignition Characteristics of HCCI Engines

2014-11-11
2014-32-0003
The chemical composition of marketed gasoline varies depending on the crude oil, refinery processes of oil refineries, and season. The combustion characteristics of HCCI engines are very sensitive to the fuel composition, and a fuel standard for HCCI is needed for HCCI vehicles to be commercially viable. In this paper, the effects of the structure of the fuel components on auto-ignition characteristics and HCCI engine performance were investigated. The engine employed in the experiments is a research, single cylinder HCCI engine with a compression ratio of 14.7. The intake manifold was equipped with a heater attachment allowing control of the intake air temperature up to 150 °C at 2000 rpm. Thirteen kinds of hydrocarbons, 4 kinds of paraffins, 3kinds of naphthenes, and 6 kinds of aromatics, were chosen for the investigation, and 20vol% of each of the pure hydrocarbons was blended with the 80 vol% of PFR50 fuel.
Technical Paper

Visualization Analysis of Diesel Combustion with Water and Diesel Fuel Emulsified Blend in a Constant Volume Chamber Vessel

2014-11-11
2014-32-0127
Diesel-like combustion of an emulsified blend of water and diesel fuel in a constant volume chamber vessel was visualized with high speed color video, further analyzing with a 2-D two color method and shadowgraph images. When the temperature at the fuel injection is 900 K, here while the combustion with unblended diesel fuel in the vessel is similar to ordinary diesel combustion with diffusive combustion, combustion with the emulsified fuel is similar to premixed diesel combustion with a large premixed combustion and very little diffusive combustion. With the emulsified fuel the flame luminosity and temperature are lower, the luminous flame and high temperature regions are smaller, and the duration of the luminous flame is shorter than with diesel fuel. This is due to promotion of premixing with increases in the ignition delay and decreases in the combustion temperature with the water vaporization.
Technical Paper

Development of Road's Gradient Anticipatory Algorithm for Hybrid Heavy Duty Truck

2014-09-30
2014-01-2377
For the purpose of reducing fuel consumption, a hybrid heavy duty truck was considered. Generally, HV (Hybrid Vehicle)'s energy is regenerated from deceleration energy in urban area. Hybrid heavy duty truck's energy is regenerated from potential energy on highway. Under this circumstance, some portion of energy may not be accumulated, because capacity of HV battery is limited. In order to maximize accumulating energy in the next descent, HV battery's energy shall be adequately reduced beforehand. This can be achieved by optimizing motor assist torque considering road's altitude and gradient. In this paper, performance of the algorithm is discussed.
Technical Paper

Emission Characteristics from After-Treatment System of Medium and Light Duty Engines

2014-04-01
2014-01-1501
1 To meet the Japan Post New-Long-Term (Japan 2009) emissions regulation introduced in 2009, The Hydrocarbon Selective Catalytic Reduction (HC-SCR) system for the NOx emission with a diesel fuel was chosen among various deNOx after-treatment systems (the Urea-SCR, the NOx storage-Reduction Catalyst and so on). The HC-SCR was adopted, in addition to combustion modification of diesel engine (mainly cooled EGR) as the New DPR system. The New DPR system for medium and light duty vehicles was developed as a world's first technology by Hino Motors. Advantages of the New DPR are compact to easy-to-install catalyst converter and no urea solution (DEF) injection (regardless urea infrastructure) as compared the Urea-SCR system.
Technical Paper

Mechanism of and Fuel Efficiency Improvement by Dimple Texturing on Liner Surface for Reduction of Friction between Piston Rings and Cylinder Bore

2014-04-01
2014-01-1661
Reducing friction between the piston ring and cylinder is an effective way of meeting the demand for lower fuel consumption in vehicle engines. To that effect, the authors have proposed a new and efficient friction reduction treatment for the cylinder. At first glance, this treatment seems similar to typical microtexture treatments, but it is built on a different approach. Through a rig tester, it was confirmed that optimizing the shape of the dimples and the treatment area for the cylinder improves FMEP between the piston ring and the cylinder liner by 17%. This report presents an analysis of the test results to explain the mechanism by which this effect is achieved. Fuel consumption was measured in an actual engine, and a maximum fuel consumption improvement of 3.2% was confirmed after conversion to the Japanese heavy duty vehicle fuel economy standards (Category T2). Lubricating oil consumption, blow-by and durability were also examined.
Technical Paper

A Study of the Rankine Cycle Generating System for Heavy Duty HV Trucks

2014-04-01
2014-01-0678
In heavy duty (HD) trucks cruising on expressway, about 60% of input fuel energy is wasted as losses. So it is important to recover them to improve fuel economy of them. As a waste heat recovery system, a Rankine cycle generating system was selected. And this paper mainly reports it. In this study, engine coolant was determined as main heat source, which collected energies of an engine cooling, an EGR gas and an exhaust gas, for collecting stable energy as much as possible. And the exergy of heat source was raised by increase coolant temperature to 105 deg C. As for improving the system efficiency, saturation temperature difference was expanded by improving performance of heat exchanger and by using high pressure turbine. And a recuperator which exchanges heat in working fluid between expander outlet and evaporator inlet was installed to recover the heat of working fluid at turbine generator. Then a working fluid pump was improved to reduce power consumption of the system.
Technical Paper

Effects of Alloying Elements on Wear Resistance of Automobile Cast Iron Materials

2014-04-01
2014-01-1011
Wear resistance is the important characteristics of cast iron materials for automobile components. Because the phenomenon of wear is a highly complicated mechanism involving many factors such as surface conditions, chemical reactions with lubricants, metals, and physics, it has not been fully explained. Therefore, it will be necessary to confirm and explain the wear mechanism to develop effective improvements. The purpose of this study was to investigate the structural change behavior and effects of alloying elements when the material top surface becomes worn, in order to improve the wear resistance of cylinder liners and other cast iron materials. For this purpose, several types of prototype materials were produced, and the relationship between components and wear resistance was investigated by using a laser microscope for quantitative observation of the degree of pearlite microstructure fineness.
Technical Paper

Identification of Factors Influencing Premixed Diesel Engine Noise and Mechanism of Noise Reduction by EGR and Supercharging

2013-04-08
2013-01-0313
To determine the engine noise reduction methods, an engine noise research was conducted experimentally with a PCCI diesel engine. The engine employed in the experiments was a supercharged, single-cylinder DI diesel engine with a high pressure common rail fuel injection system. The engine noise was sampled by two microphones and the sampled engine noise was averaged and analyzed by an FFT sound analyzer. The engine was equipped with a pressure transducer and the combustion noise was calculated from the power spectrum of the FFT analysis of the in-cylinder pressure wave form and the cross power spectrum of the sound pressure of the engine noise. It is well known that the maximum pressure rise rate is the main parameter related to the engine noise. The PCCI engine was operated at a 1.0 MPa/°CA maximum pressure rise rate to eliminate the effects of the maximum pressure rise rate, and parameters which had the dominant effect on engine noise and combustion noise were determined.
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