Tomohiko Furuhata

Effects of particulate matter on NOx removal in dielectric barrier discharges

It has been widely known that non-thermal plasma could remove nitrogen oxides (NOx). In this study, the effect of particulate matter (PM) on NOx reduction with a dielectric barrier discharge in needle to cylinder reactor was investigated experimentally. Diesel particulate filter was used as a discharge reactor, and PM that was formed by a special PM generator was loaded on it. Test gas was a mixture of NO, N2 and O2, and experiments were performed in room temperature. The results showed that fresh PM promoted NOx removal reactions in the barrier discharge field, but its effect deteriorated with elapsed time of the reaction process.

Continuous regeneration of an electrically heated diesel particulate trap: mechanism of particulate matter trapping and improvement of trapping efficiency

Abstract The mechanisms of trapping and continuous regeneration of soot particles in a newly developed diesel particulate trap based on static-electric trapping (electrical diesel particulate trap, E-DPT) are investigated. It is found from a visualization experiment that soot particles trapped on the electro-plates form soot bridges over the 1.5 mm narrow space between the electro-plates and burn out by Joules heating, due to the direct electrification through the bridges. The burning soot bridges trigger the burning of soot particles deposited throughout the electro-plates, achieving continuous regeneration. An experiment on the effect of particle charging on trapping efficiency showed that particle charging by corona discharge increases soot bridge formation, leading to a dramatic increase in soot trapping efficiency from 45 per cent for the case without particle charging to 85 per cent with particle charging. Size distribution measurements showed that the accumulation mode particles are trapped efficiently, but soot particles smaller than 80 nm increase at the exit of the E-DPT.

Substitute procedure for engine deposition test to investigate diesel and biodiesel fuel deposits

Abstract Abstract The aim of this study was to investigate fuel deposit development and its influences using simplified methods, which are referred to as the hot surface deposition test (HSDT) instead of using the engine deposition test. Both the HSDT and the engine deposition test have similar tendencies in terms of deposit development and soot fraction in deposits. The fuels tested are diesel fuel (DF), palm oil based methyl ester biodiesel fuel (B100) and bioblended DFs (B50, B20 and B5). Deposit development in the HSDT depended on the droplet impingement intervals, hot surface temperatures, fuels, deposit properties, initial stage of deposition and competition phenomena during the deposit formation. These factors determined the existence of the wet surface condition and the amounts of deposits accumulated. The initial wet surface condition was not the main reason for the rapid development of deposits. Biodiesel fuel and bioblended DF showed rapid development tendencies. Fewer amounts of deposits from ...

Study on PM Behavior in a Stack of Liquid Fueled Furnace

In order to reduce CO2 emission from combustion systems with fossil fuel, it is necessary to increase thermal efficiency of them. Heat recovery from flue gas is very effective in increasing thermal efficiency of a small furnace. Through this heat recovery, temperature of flue gas decreased with increasing a recovery amount of heat. It is feared that a decrease of temperature newly causes secondary condensed particles in a stack, and these particles become a problem in future. In this study, therefore, particulate matters (PM) in a flue gas stream from a spray combustion furnace were sampled and their compositions and size distributions were measured. As the result, it was shown that the mass of volatile matters in PM and the number of particle gradually increased along the stack. It was found that, moreover, the condensation of volatile matters probably occurred under the condition that flue gas temperature was below 460°C. From these results, it was clear that secondary condensed particles were formed in the stack.

Effect of Steam Addition on Spray Combustion Characteristics in a Small Can Type Combustor

In this study, the effect of steam addition on spray combustion characteristics was investigated experimentally. A small scale experimental spray combustor which had a swirl burner was used. Kerosene was used as the fuel. The steam flow rate was changed in the steam addition cases. Two steam addition methods (CASE 1 and CASE 2) were used. In CASE 1, the steam was directly introduced into the fuel spray. In CASE 2, the steam was mixed with air and introduced into the combustor together. The temperature, O2, CO, CO2, and NO distributions in the combustor were measured. As a result, the miximum temperature and the high temperature region in the combustion chamber were decreased by steam addition, and therefore thermal NO was effectively reduced. The effect of NO reduction in CASE 1 was larger than that in CASE 2. However, in CASE 2, more steam can be added than in CASE 1 with CO emission kept low.

Feasibility Study of a Six-stroke Diesel Engine with Common Rail Injection System

Six-stroke diesel engine proposed here has six processes in one cycle, i.e. intaka, 1st compression, 1st combustion, 2nd compression, 2nd combustion and exhaust. By the effect of direct EGR in the 2nd combustion process, NO concentration could be expected to decrease. However, by a weak mixing in the 2nd combustion process, much soot was exhausted and NO concentration was hardly decreased compared with the conventional four-stroke diesel engine. To improve the fuel/air mixing at the 2 nd combustion process, high pressure injection with common rail system was applied to the engine. As the result, NO concentration was increased owing to the increase of premixed combustion of 1st combustion process, although soot was reduced. Therefore, the 1st injection timing was extremely advanced to control the 1st combustion process. It changed 1st combustion process into HCCI-like combustion, and NO concentration was greatly decreased. Moreover, soot was reduced with no increase of NO concentration in the 2nd combustion process. As the result, trade-off curve of NO and soot was improved compared with the conventional four-stroke diesel engine. But CO concentration was increased.

Ignition Position of a Diesel Spray Impinging on a Wall : Effect of Wall Angle, Injection Pressure and Fuel Quantity

Ignition and combustion characteristics of diesel spray impinging on a wall were experimentally investigated. Ignition position and appearance position of the luminous flame kernel were stereoscopically observed using a two-way fiber optical system. Flat impingement wall was fixed in a high temperature, high pressure combustion chamber. Inclined angle of the flat wall was set at 30 degees or normal against the center axis of the injection spray. Distance from nozzle tip to the impingement point on the wall was set at 50 mm. Effects of injection pressure and fuel quantity on ignition position were investigated. As the result, ignition positions were observed near the spray periphery. And the radial position of ignition was shifted to the larger radial position when the injection pressure increased. Luminous flame appeared near the wall surface in the both cases of 30 degrees and normal impingements. And the region of luminous flame appearance was not changed significantly with an increase of injection pressure.