Browsing by Author "Ohtake, Kazutomo"

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    Influence of Gas Type and Injection System on Simultanous Reduction of Soot and NOx in IDI Diesel Engine.
    (1995-09) Mkilaha, Iddi; Kawai, Daizaburo; Inoue, Mitsunori; Naruse, Ichiro; Ohtake, Kazutomo
    Modification has been made to one of the prechambers of a 4-cylinder. IDI diesel engine used to study the combustion process, for the purpose of reducing emissions. With the provisions for optical assessment o the combustion process in the prechamber, the effect of high-pressure gas injection into the prechamber during injection has been carried out. Results of this work indicate that high-pressure gas injection during combustion can affect simultaneous soot and NOx reduction with a reasonably low amount of emission of other diesel engine pollutants. An optimum chamber type is suggested based on analysis of the effect of air, argon and nitrogen injection.
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    Reduction of pollutants from diesel exhaust by high pressure gas injection
    (1997-06) Kawai, Daizaburo; Mkilaha, Iddi; Osawa, Takuya; Naruse, Ichiro; Ohtake, Kazutomo
    In order to reduce the pollutants from diesel exhaust, high-pressure gas was injected during combustion into a modified pre-chamber of an IDI diesel engine at a varied load and gas injection timing. The result shows that high-pressure gas injection can reduce the particulates and NOx simultaneously, with little influence on the engine performance. The combustion process in the pre-chamber was visualized by means of an ultra high-speed video system and image analysis of the pictures obtained. The results of the visualization show that by injecting gas, the flame is first quenched, followed by the reduction of NOx in the pre-chamber by hydrocarbon. Although high-pressure gas injection could have caused a substantial increase in HC as a result of temperature quenching, this seems to be controlled by the consumed portion of HC during the recycling of NOx. Chemical analysis of polycyclic aromatics compounds was carried out for the purpose of establishing its variations with gas injection. It was established that gas injection not only reduces PM by oxidation of solid carbon, but also the PAH component.
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    Simultaneous reduction of particulate matter and NOx in a diesel engine by compressed gas injection: Macroscopic study at residual load
    (1997-02) Mkilaha, Iddi; Inoue, M; Kawai, Daizaburo; Naruse, Ichiro; Ohtake, Kazutomo
    A modified pre-chamber of an indirect injection (IDI) diesel engine was used to elucidate the influence on emissions of compressed air injection into the pre-chamber during combustion. The test parameters were air injection timing and arrangements of gas injection. This paper presents the experimental results for two types of injection arrangements; I- and Y-type. The I-type is arranged such that the gas injection jet and fuel injection nozzle are in opposite directions, while the Y-type is such that it forms a ‘Y’ shape with the nozzle and the passageway. Results obtained reveal that the Y-type arrangement is superior in combustion characteristics and emissions reduction to the I-type. A remarkable reduction in both particulate matter (PM) and NOx is realized at air injection timings during 35° and 65° after top dead centre (ATDC). The reduction mechanism can be explained as due to the induced turbulence which improves mixing and heat transfer. The effect of the modifications on the performance of the engine was evaluated based on the fuel economy and efficiency. This evaluation has shown that the test cylinder approximates closely to the normal cylinder of the original engine