Search

It is sometimes pointed out that Dioxins (DXNs) are contained in the exhaust gas of diesel engines. In the current stage the experimental data of DXNs from diesel engines are insufficient in order to understand their mechanism and how to reduce their generation. This paper describes the measuring results of the emitted DXNs from the diesel engine and the effect of the chlorine sources on them. The experimental result shows that the DXNs from engine and incinerator is same level when the amount of chlorine would be equalized in two combustion fields. It is found that the simple relation Y=AXB is established between DXNs concentration in the particulate matter from the diesel engine Y and the amount of chlorine in the combustion field X where the values of A and B are the expgrental constants. The relation shows it is possible to bring the DXNs from diesel engines close to the zero, if the chlorine in the motor oil and the fuel, and sea salt particles in inductien air is, cut off.

As a Birchley-Riley's fuel droplet consisted of an aqueous core embedded within a liquid fuel shell was heated in the electric furnace, the puffing and the microexplosion were observed. The waiting time for microexplosion was dominated by water content, droplet volume, fuel type and ambient temperature. When the waiting time data plot was fitted by Weibull distribution, its shape parameter was equal to 2 and the microexplosion phenomenon was classified as wear out failure type.

In both spark ignition engines and diesel engines, the exhaust gas recirculation (EGR) system is well known as an effective technique to reduce nitrogen oxides emissions. However, wear of piston rings and cylinder liners is sharply increased by EGR. It is widely considered that sulfur dioxide contained in exhaust gas is strongly related to wear. In order to clarify the sole effect of sulfur dioxide in recirculated exhaust gas on wear of piston rings and cylinder liners, we performed an experiment where sulfur dioxide was added to the intake air. Furthermore, we compared the amount of wear, which was measured experimentally, with the amount of sulfur dioxide absorbed by a lubricating oil film, which was estimated by a numerical model. Consequently, sulfur dioxide absorbed by a lubricating oil film plays an important role on wear of piston rings and cylinder liners.

In both spark ignition engines and diesel engines, exhaust gas recirculation (EGR) is well known as an effective technique to reduce emissions of nitrogen oxides. However, it has not yet been applied practically to heavy-duty diesel engines because the wear on piston rings and cylinder liners is increased by EGR. It is widely accepted that sulfur dioxide in burnt gas is strongly related to this wear increase. This paper proposes a numerical model to clarify the mechanism of wear which estimates the amount of sulfur dioxide absorbed by lubricating oil film. The calculated results show that the concentration of sulfur dioxide in lubricating oil film is increased with the increase in the rate of EGR and the reduction in engine speed, and is decreased with the decrease in engine load. The measured amount of wear on piston rings and cylinder liners is related to the concentration of sulfur dioxide in lubricating oil film.

In both spark ignition engines and diesel engines, the exhaust gas recirculation (EGR) system is well known as an effective technique to reduce emitted nitrogen oxides. However, wear of piston rings and cylinder liner is sharply increased by EGR. It is widely considered that sulfur dioxide contained in exhaust gas is strongly related to wear. In order to clarify the effect of sulfur dioxide only on wear of piston rings and cylinder liner, we performed an experiment on the addition of sulfur dioxide to intake air. Furthermore, we compared the amount of wear, which was measured experimentally, with that of sulfur dioxide diffused into a lubricating oil film, which was estimated by a numerical model. Consequently, it was found that sulfur dioxide absorbed into a lubricating oil film played an important role on wear of piston rings and cylinder liner.

In both spark ignition engines and diesel engines, the exhaust gas recirculation (EGR) system is well know as an effective technique to reduce nitric oxide emission. However, it has not been applied practically to heavy-duty diesel engines because wear of piston rings and cylinder liner is increased by EGR. It is widely considered that sulfur oxide in exhaust gas strongly relates to the wear. This paper presents a numerical model to reveal the mechanism of wear which estimates the amount of sulfur oxide diffused into lubricating oil film. The calculated results show that the sulfur oxide concentration in the oil layer is related strongly to the EGR rate, inversely with engine speed, and decreases under light load conditions. There is a good agreement between the results and the experimental facts.

The flame at the top of a burner enters the burner channel when a mixture is stopped quickly. The quenching distance measured by a burner method means the minimum width of the channel through which the flame can pass. The problems about three measurement methods are discussed with optical observation in this paper, and it is found that a tapering burner method is the most recommendable of these measurement methods are discussed with optical observation in this paper, and it is found that a tapering burner method is the most recommendable of these methods for the following reasons. When the mixture is not spark-ignited but the flame is held at the top of the burner, method with spark ignition, abrupt change of cross-sectional area of the flame entrance often prevents the flame from entering the channel. At that time, the flame does not interact with the surface of the channel. The above defects are eliminated in the tapering burner method with spark ignition.

Absorption and desorption of fuel by motor oil that coats the cylinder side wall with a thin oil film is thought to be one of the important sources of unburnt hydrocarbon emissions from spark ignition engines. The experiments presented in this paper determine the effect of oil films on unburnt hydrocarbon emissions. The exhaust gas from a combustion bomb in the presence and absence of oil has been analyzed by gas chromatography. Experiments show that the exhaust hydrocarbon concentration increases when motor oil is applied on a surface of the bomb. This result shows that absorption of the fuel occurs in the oil prior to ignition, and dissolved fuel is then desorbed into the burnt gas after the completion of combustion.

The quenching distances of mixtures of methane and hydrogen with air are determined. The quenching distances are given as a function of hydrogen percentage of the hydrogen-methane mixtures, excess air ratio and pressure of unburnt gas. It is observed that the flame quenching phenomenon has probability nature at the region where the distance of the two discs approaches the quenching distance. Futhermore, the correlation of stretch factor and quenching distances is derived and the relation of hydrocarbon emission levels of piston engines and quenching distances is discussed.

The paper describes a practical and precise analysis which concerns the matching between diesel engine and turbo-supercharger. The exhaust piping system of an actual turbocharged 4-cycle 6-cylinder diesel engine including engine cylinders and a turbine is calculated by applying the method of characteristics under the boundary conditions as exactly as possible. Since the computation at the pipe junction is extremely complex and tedious, a practical and reasonable simplification has been proposed, which accomplishes a considerable shortening of the computer time. The results of the calculation have generally agreed with the experimental measurements. The factors which influence the magnitude of the available exhaust gas energy are examined and the optimum dimensions of exhaust piping systems for the maximum energy utilization are suggested.

Flanged electrodes need to have two functions to determine the value of quenching distance with accuracy: The first function of flanged electrode is to start flame propagation at the centre of the disk. The second is to stop and quench the flame by the disks. These functions are quite dependent on the ignition energy and the diameter of the flanged disk. The experimental results confirm that the value of quenching distance is essentially independent of the ignition energy but the recommendable value of ignition energy is two or three times that of minimum ignition energy, and the measuring limit of the quenching distance linearly extends with the diameter of the disk.

Unreacted fuel in ring crevice volumes is a significant source of hydrocarbon emissions from spark ignition engines. If the ring crevice is designed with a wider clearance into which the flame will propagate, the unreacted fuel can be reduced. In this paper, the conditions of flame propagation into the ring crevice are investigated by using ionization probes imbedded in the moving piston of a four-stroke spark ignition engine. It is found that the flame propagates into the ring crevice if the quenching distance when the flame reaches the crevice is narrower than the piston top land clearance.