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Technical Paper

Stereoscopic Micro-PIV Measurement of Near-Wall Velocity Distribution in Strong Tumble Flow under Motored SI Engine Condition

In a state-of-the-art lean-burn spark ignition engine, a strong in-cylinder flow field with enhanced turbulence intensity is formed, and understanding the wall heat transfer mechanism of such a complex flow is required. The flow velocity and temperature profiles inside the wall boundary layer are strongly related to the heat transfer mechanism. In this study, two-dimensional three-component (2D3C) velocity distribution near the piston top surface was measured during the compression stroke in a strong tumble flow using a rapid compression and expansion machine (RCEM) and a stereoscopic micro-PIV system. The bore, stroke, compression ratio, and compression time were 75 mm, 128 mm, 15, and 30 ms (equivalent to 1000 rpm), respectively.
Technical Paper

Investigation on Effect of Offset Orifice Nozzle on Diesel Combustion Characteristics

Compression ignition engines provide superior thermal efficiency over other internal combustion engines. Unfortunately the combustion process is diffusive combustion, meaning a lot of fuel is impinged the on the piston and cylinder wall. This creates cooling loss coupled with smoke, CO and THC. Minimization of the nozzle orifice diameter is a simple method widely used to shorten spray penetration. However, decreasing the nozzle orifice diameter also decreases fuel flow rate resulting in a prolonged injection and combustion process and reducing thermal efficiency. An offset orifice nozzle causes less fuel impingement by shorter fuel spray penetration without significant reduction of fuel flow rate. The offset orifice nozzle was made by shifting its alignment from the center of the sac to the edge of the sac following the swirl direction. A counterbore design was applied to maintain constant orifice length.
Technical Paper

Real-World Emission Analysis Methods Using Sensor-Based Emission Measurement System

Every year, exhaust gas regulations are getting stricter with the intention to solve the average air pollution problem, however, local roadside pollution is still a pressing issue. In order to solve this local roadside pollution problem, it is necessary to evaluate and/or predict “where” and “how much” pollutants such as NOx are emitted. To predict the local roadside pollution, it is necessary to collect emissions data from various kinds of vehicles driving on real-world and analyze them. In recent years, Real Driving Emission regulations using PEMS (Portable Emission Measurement System) have been introduced mainly in Europe. A typical PEMS configuration can weigh close to 100 kg however, and its weight affects the driving conditions of vehicles running on actual roads. In this study, we focused on the analysis of real-world emissions using SEMS (Sensor-based Emission Measurement System).
Journal Article

Combustion Characteristic of Offset Orifice Nozzle under Multi Pulse Ultrahigh Pressure Injection and PCCI Combustion Conditions

CI engines provide higher thermal efficiency compared to other internal combustion engines. On the other hand large amounts of smoke and NOx are produced during combustion. Smoke and NOx can be reduced by applying Premixed Charge Compression Ignition (PCCI) combustion. Unfortunately, the problems of PCCI combustion include unstable start of combustion and limited operating range. The multi-pulse ultrahigh pressure injection allows fuel to control PCCI combustion. The objective of offset orifice nozzle is to improve mixture formation and shorten spray penetration in order to increase thermal efficiency and control PCCI combustion. The offset orifice nozzle was designed by shift orifice aliment from into the sac center to edge of sac follow swirl direction. Counter bore design was applied to offset orifice nozzle in order to keep the constant orifice length as standard nozzle.
Technical Paper

Investigation on Premixed Charge Compression Ignition Combustion Control Using Multi Pulse Ultrahigh Pressure Injection

Compression ignition (CI) engines provide higher thermal efficiency compared to other internal combustion engines although large amounts of NOx and soot are produced during combustion. NOx and soot emissions can be reduced by using Premixed Charge Compression Ignition (PCCI) combustion. However, the problems of PCCI combustion include limited operating range, unstable start of combustion and an increase in combustion noise. The multi-pulse ultrahigh pressure injection allows fuel to be injected near TDC, improving mixture formation and enhancing the possibility to extend the operating range of PCCI combustion. The objective of this paper is to control and extend the operating range of PCCI combustion using multi-pulse ultrahigh pressure injection. This has not been studied before. Combustion characteristics were investigated using apparent rate of heat release analysis, heat balance analysis, exhaust emission measurement and soot concentration measurement.
Technical Paper

A Cycle-to-Cycle Variation Extraction Method for Flow Field Analysis in SI IC Engines Based on Turbulence Scales

To adhere to stringent environmental regulations, SI (spark ignition) engines are required to achieve higher thermal efficiency. In recent years, EGR (exhaust gas recirculation) systems and lean-burn operation has been recognized as key technologies. Under such operating conditions, reducing CCV (cycle-to-cycle variation) in combustion is critical to the enhancement of overall engine performance. Flow-field CCV is one of the considerable factors affecting combustion in engines. Conventionally, in research on flow fields in SI engines, the ensemble average is used to separate the measured velocity field into a mean component and a fluctuation component, the latter of which contains a CCV component and a turbulent component. To extract the CCV of the flow field, previous studies employed spatial filter, temporal filter, and POD (proper orthogonal decomposition) methods.
Technical Paper

Heat Transfer Analysis in a Diesel Engine Based on a Heat Flux Measurement Using a Rapid Compression and Expansion Machine

To investigate the heat transfer phenomena inside the combustion chamber of a diesel engine, a correlation for the heat transfer coefficient in a combustion chamber of a diesel engine was investigated based on heat flux measured by the authors in the previous study(8) using the rapid compression and expansion machine. In the correlation defined in the present study, thermodynamically estimated two-zone temperatures in the burned zone and the unburned zone are applied. The characteristic velocity given in the correlation is related to the speed of spray flame impinging on the wall during the fuel injection period. After the fuel injection period, the velocity term of the Woschni’s equation is applied. It was shown that the proposed correlation well expresses heat transfer phenomena in diesel engines.
Technical Paper

The Effect of Exhaust Gas Recirculation on Performance and Emission of Ethanol Fumigated Diesel Engine

Primary energy source such as fossil fuel keep decreasing due to various kind of usage. According to less amount of the fossil fuel, human seeks for an alternative fuel source such as alcohol. Alcohol like ethanol can be produced easily from strarchy plant. But using alcohol as blended fuel with diesel fuel doesn't work well because alcohol has low cetane number, lack of lubricity and very low miscibility with diesel fuel. To overcome this, fumigation system or port fuel injection of alcohol seems interesting. Although it requires more complicate system but it can compensate the miscibility issue and alcohol can be used in higher dose to give more energy. Diesel engine produces a lot of emission such as NOx and some other carbon content emission like HC, CO and soot due to they run in lean condition as their characteristic. Modern diesel engines are now coupled with exhaust gas recirculation system to help reduce in main emission like NOx.
Technical Paper

Effect of Biofuel and Soot on Metal Wear Characteristic Using Electron Microscopy and 3D Image Processing

The soot contamination in used engine oils of diesel engine vehicles was about 1% by weight. The soot and metal wear particle sizes might be in the range of 0-1 µm and 1-25 µm, respectively. The characteristics of soot affecting on metal wear was investigated. Soot particle contamination in diesel engine oil was simulated using carbon black. Micro-nanostructure of soot particles were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and laser diffraction spectroscopy (LDS). The metal wear behavior was studied by means of a Four-Ball tribology test with wear measured. Wear roughness in micro-scale was investigated by high resolution optical microscopy (OM) , 3D rendering optical technique and SEM image processing method. It was found that the ball wear scar diameter increased proportionally to the soot primary particle size. The effect of biodiesel contamination were also increasing in wear scar diameter.
Technical Paper

Impact of Biodiesel on Small CI Engine Combustion Behavior and Particle Emission Characteristic

Diesel engines are high thermal efficiency because of high compression ratio but produce high concentration of particulate matter (PM) because of direct injection fuel diffusion combustion. PM must be removed from the exhaust gas to protect human health. This research describes biodiesel engine performance, efficiency and combustion behavior using combustion pressure analyzer. It was clearly observed that PM emitted from CI engines can be reduced by using renewable bio-oxygenated fuels. The morphology and nanostructure of fossil fuel and biofuel PMs were investigated by using a Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The morphology of biodiesel and diesel doesn’t have much different in the viewpoint of particulate matter trapping using DPF micro surface pores. The agglomerated ultrafine particles and primary nanoparticles sizes of diesel and biodiesel engine’s PM are approximately 50-500 nm and 20-50 nm, respectively.
Technical Paper

Characterization of Biodiesel Particle Emission in Trapping and Regeneration Processes on Cordierite Diesel Particulate Filter

As well-known, the diesel engine has the highest thermal efficiency at the same load as compared with internal combustion engine but its disadvantage is particulate matter (PM) emitted to the atmosphere. The studies of this paper were divided into two parts. The first part studied the quantity of PM from the both diesel and biodiesel fuels at 80% load (2400 rpm) by the trapping process on diesel particulate filter (DPF) used in a partial flow dilution tunnel. The second part studied the regeneration process of PM under the flow rate of oxygen and nitrogen gas of 13.5 L/min with 10%, 15%, and 21% of oxygen gas. The result showed that amount of PM from biodiesel fuel was lower around two times than PM from diesel fuel. The duration in regeneration process of biodiesel's PM was shorter than diesel while increasing of oxygen percentage can reduce regeneration time.
Technical Paper

NOx Reduction with the HC-SCR System over Cu/Zeolite Based Catalysts

Diesel engine is one the effective solutions for reducing CO2 and recognized as a leading candidate for mitigating global warming. To comply with increasingly stringent emission standards, all diesel engines require some sort of NOx control systems such as selective catalytic reduction (SCR) systems. The SCR catalyst for reducing NOx from diesel engines is classified into two groups, urea-SCR and HC-SCR catalyst, respectively. Although the urea-SCR catalyst is widely recognized as promising de-NOx technology in respect to the NOx conversion efficiency, it have some outstanding issues such as ammonia slip, urea injection, storage space, freezing and some infrastructures for supplying urea water solutions. In an attempt to overcome the inherent shortcoming of existing urea-SCR catalyst, hydrocarbons have been considered as alternative reducing agents for SCR process, instead of NH3.
Technical Paper

Comparison Study on Fuel Properties of Biodiesel from Jatropha, Palm and Petroleum Based Diesel Fuel

The increase of air pollution and global warming is a threat for human life. Besides, the price of petroleum is increasing rapidly and the resources are diminishing. This obliged scientists and engineers to look for alternative sources of energy, which are cleaner and more sustainable. Biodiesel, defined as mono-alkyls of esters from vegetable oils and animals fat, is a cleaner renewable fuel and has been considered as the best alternative for petroleum based diesel fuel hence it can be used in any compression ignition engines without any significant modification. The main advantages of using biodiesel are its renewability and better quality of exhaust gas emissions due to their higher content of oxygen. The produce less soot and hence the feed stuck is plant it will regenerate the CO2 by the photosynthesis which ensures the renewability and reduces global warming.
Technical Paper

Physical Characterization of Biodiesel Particle Emission by Electron Microscopy

Nanostructures of diesel and biodiesel engine particulate matters (PMs) were investigated by using a Transmission Electron Microscopy (TEM). The average single particle sizes of biodiesel and diesel PMs are approximately 30-40 nm and 50-60 nm, respectively. Image processing process was used to estimate each carbon platelet length by using TEM image. The average carbon platelet length of biodiesel and diesel PMs are in the range of 0.1-7.0 nm. Moreover, carbon atoms per cubic volume of PMs are approximately 500-900. The result shows that engine load and fuel property are strongly impact on the size of single particle and carbon atom density of particle. This is one of interesting behaviors need to be investigated for better understanding. The results of this research would be used as basic information for design and develop removing process of PM emitted from engine combustion which using in diesel and biodiesel fuels.
Technical Paper

A Design Guide for Wet Multiple Plate Clutches on Forklift Truck Transmissions Considering Strength Balance between Friction Material and Mating Plate

Wet multiple plate clutches consist of friction plates, on which a friction material is bonded, and mating plates that are plain metal plates. Since the frequency and the range of load in the field of forklift trucks vary widely and are more severe than those for passenger cars, the wet multiple plate clutches on forklift trucks are often damaged. Damaged clutches that were returned from the field typically had 3 types of symptoms: 1.Only the friction material was damaged, 2.Only the mating plates were deformed, 3.Both symptoms were observed. It was clear that the cause of these symptoms depended on the difference of the operating application and the strength criteria of each part. This showed that a design guide for wet multiple plate clutches considering the strength balance between the two parts according to the work application was required. The relevant flow chart of this design process was proposed.
Technical Paper

Investigation of Effects of Ignition Improvers on Ignition Delay Time of Ethanol Combustion with Rapid Compression and Expansion Machine

This work investigates the effects of ignition improvers on the ignition and combustion characteristics of hydrous ethanol with 5% by weight water and 1% by weight Lauric acid (Eh95) under simulated diesel engine conditions using the rapid compression and expansion machine (RCEM). Results indicate that hydrous ethanol with commercial additive (ED95) and hydrous ethanol with 5% by weight glycerol ethoxylate in hydrous ethanol exhibit a near identical rate-of-pressure-rise and heat release rate. Ignition delay of hydrous ethanol with 5% by weight glycerol ethoxylate is shorter, but hydrous ethanol with 1% by weight glycerol ethoxylate has longer ignition delay time and different combustion characteristics compared with hydrous ethanol with commercial additive (ED95). Hydrous ethanol with 1% by weight glycerol ethoxylate and hydrous ethanol with 5% by weight glycerol ethoxylate are considered suitable fuels for high compression-ratio diesel engines.
Technical Paper

Low Temperature Starting Techniques for Ethanol Engine without Secondary Fuel Tank

The present study aims to investigate the parameters affecting cold start characteristics of ethanol at low temperature, and suggest a solution to avoid cold starting problem without the installation of second fuel tank. The testing engine is a 125cc volume displacement, single-cylinder four strokes SI engine with fuel injection and ignition timing system controlled by ECU (electronic control unit). The cold starting performance tests were extensively conducted with different percentages of ethanol blends, surrounding temperatures, heating inside combustion chamber, heater injector, pre-cranking without fuel injection, and amount of fuel injection. From the experimental results, when using ethanol fuel in conventional engine, the problem of cold starting was observed at surrounding temperature lower than 20°C for ethanol. Increasing of injection duration can lower the possible cold start temperature of neat ethanol.
Technical Paper

Experimental Investigation in Combustion Characteristics of Ethanol-gasoline Blends for Stratified Charge Engine

The increasing of global energy demand and stringent pollution regulations have promoted research on alternative fuels. In Thailand, ethanol, can be produced from many sources of national agriculture products as renewable fuel, which was strongly promoted by government due to its many merits for use in transportation field. In this study, combustion characteristics of ethanol-gasoline blend (20%, 85%, and 100%) as well as pure gasoline (E0) were investigated by using a swirl-generated constant volume combustion chamber. Flame propagations of different fuel blends were observed by high speed Schlieren photography technique while pressure history data were recorded for detailed combustion analysis. Combustion behavior, combustion duration and rate of pressure rise of all tested fuels were investigated in various swirl intensities and equivalence ratios. In addition, effect of swirl intensities and ethanol concentration on lean misfire limit were also discussed.
Technical Paper

Simultaneous Measurements of Temperatures of Flame and Wall Surface in a Combustion Chamber of Diesel Engine

In order to investigate the combustion phenomena in a combustion chamber of the diesel engine at transient operations, the simultaneous measurements of temperatures of flame and wall surface in a combustion chamber were conducted. The new technique for simultaneous measurements of flame temperature and wall surface was developed. Laser-Induced phosphorescence was used for the measurement of wall surface temperature which was coupled with the flame temperature measurement by a two-color pyrometry. The NOx and soot emissions were also measured simultaneously in transient operations. The relation between the temporal changes of emissions and temperatures of flame and surface wall are discussed. The results show that the temporal change of NOx emission during transient operation is similar to that of the average gas temperature in a chamber. On the other hand, the temporal change of soot emission is similar to neither that of flame temperature nor that of average gas temperature.
Technical Paper

Extension of Lean and Diluted Combustion Stability Limits by Using Repetitive Pulse Discharges

A newly developed small-sized IES (inductive energy storage) circuit with a semiconductor switch at turn-off action was successfully applied to an ignition system. This IES circuit can generate repetitive nanosecond pulse discharges. An ignition system using repetitive nanosecond pulse discharges was investigated as an alternative to conventional spark ignition systems in the previous papers. Experiments were conducted using constant volume chamber for CH₄ and C₃H₈-air mixtures. The ignition system using repetitive nanosecond pulse discharges was found to improve the inflammability of lean combustible mixtures, such as extended flammability limits, shorted ignition delay time, with increasing the number of pulses for CH₄ and C₃H₈-air mixtures under various conditions. The mechanisms for improving the inflammability were discussed and the effectiveness of IES circuit under EGR condition was also verified.