Tadashi Murayama

Description and Analysis of Diesel Engine Rate of Combustion and Performance Using Wiebe's Functions

Two laboratory engines, one direct injection and one indirect injection, were operated for a range of speeds, loads, injection timings, fuels, and steady and transient conditions. Rate of combustion data were derived and analyzed using a double Wiebes function approximation. It is shown that three of the six function parameters are constant for a wide range of conditions and that the other three can be expressed as linear functions of the amount of fuel injected during ignition lag. Engine noise, smoke, and thermal efficiency correlate with the parameters describing the amount of premixed combustion and diffusive combustion duration. These characteristics may be optimized by reducing the quantity of premixed combustion while maintaining the duration of diffusive combustion to less than 60 /sup 0/CA.

Low carbon flower buildup, low smoke, and efficient diesel operation with vegetable oils by conversion to mono-esters and blending with diesel oil or alcohols

The purpose of this investigation is to evaluate the feasibility of rapeseed oil and palm oil for diesel fuel substitution in a naturally aspirated DI Diesel engine is evaluated. Means to reduce the carbon deposit buildup in vegetable oil combustion is found. In the experiments, the engine performance, exhaust gas emissions, and carbon deposits are measured for a number of fuels: rapeseed oil, palm oil, methylester of rapeseed oil, and these fuels blended with ethanol or diesel fuel with different fuel temperatures. Both of the vegetable oil fuels generate an acceptable engine performance and exhaust gas emission levels for short term operation, but they cause carbon deposit buildups and sticking of piston rings after extended operation. Practical solutions to overcome the problems are: increasing the fuel temperature to over 200/sup 0/C, blending 25 vol % diesel fuel in the vegetable oil, blending 20 vol % ethanol in the fuel, or converting the vegetable oils into methylesters.

Performance and durability of Pt-MFI zeolite catalyst for selective reduction of nitrogen monoxide in actual diesel engine exhaust

Abstract Selective catalytic reduction of nitrogen monoxide (NO) by hydrocarbon in an oxidizing atmosphere has been studied over platinum-MFI zeolite (Pt-MFI) in synthesized or actual diesel engine exhaust gases. The activity of Pt-MFI in the synthesized gas, containing 10% water, changed in the early stage of the use, leveled off after 150–200 h, and remained constant for more than 800 h. The Pt-MFI catalyst also showed stable activity at 423–773 K and 10 000–150 000 h − (gas hourly space velocity) in actual engine exhaust with light oil as a fuel. The degree of nitrogen monoxide reduction increased linearly upon addition of ethylene into the exhaust gas.

Experimental Reduction of NOx, Smoke, and BSFC in a Diesel Engine Using Uniquely Produced Water (0 - 80%) to Fuel Emulsion

With the aid of static mixer and non-ionic emulsifying agent, a comparatively stable water-fuel emulsion was obtained. Engine performance in a 4 cycle direct injection engine using these fuels were studied. A large reduction of NOx concentration was obtained over the wide range of engine operations, in spite of increased ignition lag and rapid combustion. Furthermore, improvements of economy and reduction of exhaust smoke were obtained. The reduction of NOx concentration, fuel consumption and smoke were even more remarkable when compared with operating same engine with water fumigation.

Characteristics of Diesel Soot Suppression with Soluble Fuel Additives

Experiments on a large number of soluble fuel additives were systematically conducted for diesel soot reduction. It was found that Ca and Ba were the most effective soot suppressors. The main determinants of soot reduction were: the metal mol-content of the fuel, the excess air factor, and the gas turbulence in the combustion chamber. The soot reduction ratio was expressed by an exponential function of the metal mol-content in the fuel, depending on the metal but independent of the metal compound. A rise in excess air factor or gas turbulence increased the value of a coefficient in the function, resulting in larger reductions in soot with the fuel additives. High-speed soot sampling from the cylinder showed that with the metal additive, the soot concentration in the combustion chamber was substantially reduced during the whole period of combustion. It is thought that the additive acts as a catalyst not only to improve soot oxidation but also to suppress soot formation. Furthermore, the additives resulted in decreased ignition temperatures and enhanced oxidation of the additive-containing soot.

W/O emulsion realizes low smoke and efficient operation of DI engines without high pressure injection

This paper describes an experiment in which water-in-gas oil emulsified fuel is used without high pressure or high injection rate to improve engine performance parameters such as smoke, NO/sub chi/, and BSFC in a DI diesel engine. The results are compared with high pressure and high injection rate operation using gas oil.

NOx reduction characteristics of Pt-ZSM-5 catalyst with diesel engine exhaust

The platinum ion-exchanged ZSM-5 zeolite catalyst (Pt-5), which reduces nitrogen oxides (NOx) in the presence of oxygen and hydrocarbons, was applied to actual diesel engine exhaust. Compared to the Cooper ion-exchanged ZSM-5 zeolite catalyst, the Pt-Z had higher NOx reduction efficiency, ηNOx = 33%, and lower activation temperature, 250°C, in normal engine operation. It was found that water in the exhaust gas did not apparently affect the NOx reduction, while the reduction efficiency was significantly affected by the aspect ratio of the catalyst reactor and by the shape of the catalyst, i.e. pellet or honeycomb.

Improvement of performance and emissions of a compression ignition methanol engine with dimethyl ether

Dimethyl ether (DME) has very good compression ignition characteristics and can be converted from methanol using a {gamma}-alumina catalyst. In this study a torch ignition chamber (TIC) head with TIC close to the center of the main combustion chamber was designed for the TIC method. The possibility of improvements in reducing the quantities of DME and emission were investigated by optimizing the TIC position, methanol injection timing, DME injection timing, and intake and exhaust throttling. It was found that the necessary amount of DME was greatly reduced when optimizing methanol and DME injection timings. 2 refs., 16 figs., 1 tab.

The effect of fuel properties on diesel engine exhaust particulate formation.

Fuel properties affect diesel engine particulate because the thermal cracking and condensation polymerization of various fuels are different. This report investigates the thermal cracking and condensation polymerization processes of various fuels with different molecular structure and carbon number in a nitrogen atmosphere using a thermal cracking apparatus.

A SIMULATION OF DIESEL ENGINE COMBUSTION NOISE

The influence of the shape of the burning rate curve on engine noise, especially on combustion noise was studied in detail and clarification of the relationship was successfully made. /GMRL/