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A new impinging nozzle head attached on a normal injection nozzle was designed for improving the performance and combustion of DI diesel engine. Since the fuel is directly injected to the nozzle head at a very short distance from a spray tip of nozzle in a DI diesel engine, the fuel particles will be improved in spray diffusion and distribution. In the case of a prototype injection nozzle with four orifices, the spray angle from each orifice is narrow and similar to the shape of conifer's leaves. By using of the new designed impinging nozzle head, however, an improved spray angle and distribution of fuel and a better starting performance at very low temperature have been observed.

Several different shaped impinging nozzle heads have been studied. A small impinging nozzle head supported by single stay shows a good spray distribution, and economic fuel consumption under middle engine loads and all engine speeds In a single cylinder DI diesel engine without air swirl Intake system.

This report describes with the performance test of a diesel engine using a new variable scroll type turbocharger (VS turbocharger). The experimental variable scroll is relatively a simple structure in which several scroll pieces are jointed by pins, located inside of exhaust turbine inlet flow passage. The scroll is varied by the control rod according to exhaust flow volume, and as a result, the A/R ratio that effects to the performance of turbocharger is varied. To compare the performances of variable scroll type turbocharger with a conventional turbocharger with waste gate, a test of diesel engine equipped with each was performed. The experimental results show that VS turbocharger increases more than the conventional turbocharger in boost pressure at lower engine speed, and the wide torque range is ensured. Also, the experimental scroll pieces did not showed signs of trouble from heat wear during experimentation ensuring reliability.

A new variable scroll type turbocharger has been developed, which is a kind of variable geometry turbocharger. This paper describes a method for determining the shape of a scroll chamber of a turbine housing of the turbocharger. The basic idea is to vary the flow area using the scroll according to exhaust gas flow. The scroll consists of several scroll pieces joined to form a linked variable structure. The shape of the scroll pieces is decided on the basis of an Archimedes’ curve. The device developed is relatively simple.

A comprehensive two-dimensional gas chromatography with time of flight mass spectrometer (GC x GC - TOFMS) was applied to analyze combustion products in exhaust gas emitted by a spark ignition combustion engine. N-heptane and toluene were used as fuel. For identification of detected compounds, NIST library search of the GC Image software was used. In exhaust gas of SI combustion using n-heptane as fuel, many types of branched chain compounds, aromatic compounds and naphthenic compounds were detected. On the other hand, in toluene SI combustion, most components of exhaust gas were aromatic compounds.

The objectives of this study are to investigate the effects of premixed charge compression ignition (PCCI) strategies with split injection on soot emission characteristics. The split injection conditions included three injection intervals (1.1 ms, 1.3 ms, and 1.5 ms) and three injection quantity fraction ratios (Q1/Q2 = 10.0/14.6 mm3/st, 15.2/9.4 mm3/st, and 20.0/4.6 mm3/st). The results in real engine tests showed that shorter injection intervals, and the 1st injection quantity contributes to reduced soot emissions. A rig test with high-pressure and high-temperature constant-volume vessel (CVV) and a two-dimensional (2D) model piston cavity were used to determine correlations between injection conditions and soot emissions. During the rig test, fuel was injected into the CVV by a single-hole nozzle under split injection strategies. The injection strategies include the same injection intervals and quantity fraction ratios as in the real engine test.

As an effective means of improving engine output, turbocharging has been widely used in engines. However, due to the inherent mismatch of a turbocharger to a reciprocating machine, a turbocharged machine does have some drawbacks,such as the reduction in transient performance, low torque backup, low torque and etc. One solution to these problems is to dynamically vary the size of the turbine stage, reducing the swallowing capacity of the turbine at lower gasflows and increasing the swallowing capacity at high gasflows. A turbocharger fitted with such a turbine is called “Variable Geometry” turbocharger. In general, there are two types of variable nozzle turbocharger. One is the traditional gas turbine approach of using a set of individually pivotable nozzle guide vanes (1) (2), and the other is with axial movable nozzle vanes (3) (4) (5).

In order to measure the droplets and vapor concentration inside a fuel spray, a dual-wavelength laser absorption-scattering technique was developed using the second harmonic (532nm) and the fourth harmonic (266nm) of a Nd:YAG laser and using dimethylnaphthalene as the test fuel. The investigation results show that dimethylnaphthalene, which has physical properties similar to diesel fuel, is almost transparent to visible light near 532nm and is a strong absorber of ultraviolet light near 266nm. Based on this result, the vapor concentration in a fuel spray can be determined by the two separate measurements: a transmission measurement at a non-absorbing wavelength to detect the droplets optical thickness and a transmission measurement at an absorbing wavelength to detect the joint vapor and droplets optical thickness. The droplets density can be determined by extinction imaging through the transmission at the non-absorbing wavelength.

This paper is describes the progress of the development of continuous variable valve timing mechanism by the combination of the three-dimensional cam and the moving rocker arm, and the performance of 4 cylinder gasoline engine with this mechanism. This continuous valve timing mechanism is very concise. Through the trial product's experiment, it proved to be reliable. Furthermore, engine performance demonstrated high torque and low fuel consumption in wide engine speed range.

An axially movable vane turbocharger has been modified based on the basic aerodynamic design principles, and good performance is obtained. The details of design and engine bench testing results of several vane variations are presented, and the most suitable assembly nozzle with two separate vanes is then developed. These have produced a simple design with a minimum number of the moving parts. Experimental data also show that the new turbocharger efficiently expands the effective torque band and get the low fuel consumption at a wide engine speed range.

An author's previous studies addressed a combustion system which reduces emissions, noise, and fuel consumption by using PCCI with the split injection of fuel. This concept relies on the premixed combustion of the first injected fuel and accelerated oxidation by the second injected fuel. Although this combustion system requires the optimization of the timing of the second injection, the details of how noise and emissions are reduced have not been elucidated. In this paper, the authors explain the mechanism whereby emissions and noise are reduced by the second injection. In-cylinder visualizations and numerical simulations both showed an increase in smoke and CO as the second injection timing was advanced, as induced by the inhibited oxidation of the rich flame. When the second injection timing is excessively retarded, the amount of soot forming around the near-nozzle increased.

Multi-cylinder hydrogen-absorbing alloy tanks for fuel cell vehicles have 10 to 40 metallic cylinders that are bundled and filled with hydrogen-absorbing alloy. In this system, the cylinders themselves act as a heat exchanger and the working pressure is lowered to 10 to 20 MPa compared with high-pressure MH tanks. Moreover, both heat conduction and mass reduction can be achieved by reducing the wall thickness of the cylinders. A model verification experiment was conducted using a one-quarter-scale prototype of a full size tank, and a conduction simulation model verified in the experiment was used to predict the performance of the full size tank. Results showed that it is possible to fill the tank with hydrogen to 80% of its capacity in a five-minute filling time, although issues related to heat conductivity performance require improvement. Accordingly, it may be possible to adopt this tank as part of a system if the storage amount of the hydrogen-absorbing alloy can be increased.

This paper is described the performance of VVT using engine cycle simulation software and the verification of compression ignition combustion in practical engine. It was predicted by engine cycle simulation that the control of high temperature EGR by the application of VVT improved thermal efficiency markedly by compression ignition combustion. A trial VVT is applied to an actual engine, and compression ignition combustion is realized.

The effect of injection pressure ranging from 100 to 300MPa on the ignition, flame development and soot formation characteristics of biodiesel fuel spray using a common rail injection system for direct injection (D.I.) diesel engine was investigated. Experiments were carried out in a constant volume vessel under conditions similar to the real engine condition using a single hole nozzle. Biodiesel fuels from two sources namely; palm oil (BDFp) and cooked oil (BDFc) with the commercial JIS#2diesel fuel were utilized in this research. The OH chemiluminescence technique was used to determine the ignition and the lift-off length of the combusting flame. The natural luminosity technique was applied to study the flame development and the two color pyrometry was applied for the soot formation processes. Ignition delay decreased as the injection pressure progressed from 100 to 300MPa. This was as a result of the enhanced mixing achieved at higher injection pressures.

We have constructed a quasi-2-dimensional NH₃-SCR model with detailed surface reactions to analyze the NOx conversion mechanism and reasons for its inhibition at low temperatures. The model consists of seven detailed surface reactions proposed by Grozzale et al., and calculates longitudinal gas flow, gas phase-catalyst phase mass transfer, and mass diffusion within the catalyst phase in the depth dimension. Using the model, we have analyzed the results of pulsed ammonia (NH₃) feed tests at various catalyst temperatures, and results show that ammonium nitrate (NH₄NO₃) is the inhibitor in NH₃-SCR reactions at low temperatures. In addition, we found that cutting the supply of NH₃ causes decomposition of NH₄NO₃, providing surface ammonia (NH₄+), which rapidly reacts with adjacent NOx, leading to an instantaneous rise in nitrogen (N₂) formation.

The multi-impingement-wall head (MIW head) is designed to be located at the center of combustion chamber and is attached to the cylinder head. In this paper, a new concept of the MIW head has been investigated to obtain a three-dimensional diffusion spray for improving the combustion and performance of a DI diesel engine. Four Types of combustion chambers, the troidal type used in a normal DI diesel engine, and the reentrant types with a projection, with a cutouts, and their combinations (with both projection and cutouts) have been used in the NICS-MH engine experiments. Based on the experimental results of engine performance, it shows that the reentrant type of combustion chamber with a projection and a cutouts has a better fuel consumption and produces lower harmful exhaust gases (HC, NOx and smoke) than those of other NICS-MH engines.

A three-dimensional diffusing spray using the multi-impingement-wall head (MIW head) has been proposed to form air-fuel mixtures in a simple DI diesel engine. In this paper, effects of the width of the MIW head on spray pattern, distribution and engine performance have been investigated. In the fuel spray and engine performance experiments, an optimal width of MIW head results in the collision of fuel particles to advantageous position in a combustion chamber for obtaining a good fuel spray distribution. The minimum BSFC is almost the same value as that of a single DI diesel engine, the HC and smoke densities are reduced and the NOx density is shown a tendency to some increase under part load and decrease under full load. A relatively slow heat release rate and maximum temperature duration of the MIW head can be obtained by shortening the ignition delay.

Fuel injected from multi-hole injector with a small injection angle (100°) is impinged to the multi-impingement-wall head(MIW head), which is located in the center of combustion chamber and is attached to the cylinder head. The fuel is diffused into the piston cavity to form a three-dimensional diffusion spray. The main advantage of diffusion spray is that the effects of the fuel impinging diffusion and the collision between fuel particles can be obtained. Based on the concept of MIW head, the experimental results show that the combustion performance and the fuel consumption have been improved. Besides, the NOx, HC and smoke densities of the exhaust gas of a diesel engine have been reduced.