• 제목/요약/키워드: 4-Cycle High Speed Engine

검색결과 43건 처리시간 0.025초

장-행정 저속 4 사이클 디젤기관의 제작 및 최적 연소조건에 관한 연구 (A Study on Optimal Combustion Conditions with a Design and Manufacture of the Long-Stroke Slow Speed 4 Cycle Diesel Engine)

  • 장태익
    • Journal of Advanced Marine Engineering and Technology
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    • 제28권3호
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    • pp.551-558
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    • 2004
  • Recently, fuel prices have been continually raised in diesel engine. Such a change in the fuel price influences enormously the development trend of marine diesel engines for slow speed, In other words, the focus was shifted from large diameter and high speed to low fuel consumption. Accordingly, more efforts are being made for engine manufacturing and development to develop highly efficient engines. In this study. a single cylinder 4 stroke cycle DI slow speed diesel engine was designed and manufactured, a 4 stroke cycle was configured and basic performances were evaluated. The results are as follows. The optimal fuel injection timing had the lowest value when specific fuel consumption was in BTDC 8~$10^{\circ}$, a little more delayed compared to high speed diesel engines. Cycle variation of engines showed about 5% difference at full loads. This is a significantly small value compared to the cycle variation in which stable operation is possible, showing the high stability of engine operation is good. The torque and brake thermal efficiency of engine increased with an increase of engine 250-450 rpm. but fuel consumption ratio increased from the 450 rpm zone and thermal efficiency abruptly decreased. Mechanical efficiency was maximally 70% at a 400 rpm that was lower than normal engines according to the increase of mechanical frictional loss for cross head part. The purpose of this study was to get more practical engines by comparing the above results with those of slow speed 2 stroke cycle diesel engines.

Effects of the Intake Valve Timing and the Injection Timing for a Miller Cycle Engine

  • Han, Sung-Bin;Chang, Yong-Hoon;Choi, Gyeung-Ho;Chung, Yon-Jong;Poompipatpong, Chedthawut;Koetniyom, Saiprasit
    • 에너지공학
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    • 제19권1호
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    • pp.32-38
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    • 2010
  • The objective of the research was to study the effects a Miller cycle. The engine was dedicated to natural gas usage by modifying pistons, fuel system and ignition systems. The engine was installed on a dynamometer and attached with various sensors and controllers. Intake valve timing, engine speed, load, injection timing and ignition timing are main parameters. Miller Cycle without supercharging can increase brake thermal efficiency 1.08% and reduce brake specific fuel consumption 4.58%. The injection timing must be synchronous with valve timing, speed and load to control the performances, emissions and knock margin. Throughout these tested speeds, original camshaft is recommended to obtain high volumetric efficiency.

Development and performance analysis of a Miller cycle in a modified using diesel engine

  • Choi, Gyeung-Ho;Poompipatpong, Chedthawut;Koetniyom, Saiprasit;Chung, Yon-Jong;Chang, Yong-Hoon;Han, Sung-Bin
    • 에너지공학
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    • 제17권4호
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    • pp.198-203
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    • 2008
  • The objective of the research was to study the effects of Miller cycle in a modified using diesel engine. The engine was dedicated to natural gas usage by modifying pistons, fuel system and ignition systems. The engine was installed on a dynamometer and attached with various sensors and controllers. Intake valve timing, engine speed, load, injection timing and ignition timing are main parameters. The results of engine performances and emissions are present in form of graphs. Miller Cycle without supercharging can increase brake thermal efficiency and reduce brake specific fuel consumption. The injection timing must be synchronous with valve timing, speed and load to control the performances, emissions and knock margin. Throughout these tested speeds, original camshaft is recommended to obtain high volumetric efficiency. Retard ignition timing can reduce $NO_x$ emissions while maintaining high efficiency.

흡기계의 동적효과가 기관성능에 미치는 영향 (The dynamic effects of intake system on the engine performance)

  • 조진호;김병수
    • 오토저널
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    • 제9권3호
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    • pp.85-93
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    • 1987
  • The intake system of 4-cycle, 4-cylinder reciprocating engine is investigated the simple model composed of vessel, duct and throttling part. The numerical calculation based on the simulation is performed for the flow phenomena including heat transfer, friction and bend of duct at each part. In the multi-cylinder engine, the volumetric efficiency is increased a little as the junction location is closed to cylinder at the engine speed having maximum volumetric efficiency. The configuration and dimension of intake system have an influence on the inertia effect by resistance and pressure variation, and the magnitude of that is varied by the engine speed. Thus the volumetric efficiency is correlative to them. The volumetric efficiency is high as the intake valve close is advanced at the low engine speed, and is delayed at high speed.

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4행정 중속 디젤기관의 스모크리스 시동 (Smokeless Starting for 4 Cycle Medium Speed Diesel Engine)

  • 정석호
    • 동력기계공학회지
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    • 제18권4호
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    • pp.11-16
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    • 2014
  • Although smoke emitted from ships is not included in IMO(International Maritime Organiztion) regulation yet, it is one of the substance what is polluting mainly the air. Especially, its concentration is very high when an engine is started and a load is rapidly changed. This is caused by unburned fuel what is injected more than necessary quantity after combustion period. It is possible to decrease smoke concentration emitted at starting engine by controlling fuel injection quantity, but it is concerned that time to rated speed must be spent. Then a governor what can reduce the smoke concentration without a loss of time to rated speed is needed. We adopted a electro-hydraulic governor what can control dual fuel start limit function and achieved very low level of smoke concentration without greater the loss of time to rated speed.

고속디이젤 기관의 점성비틀림 진동댐퍼에 관한 연구 (A study on the viscous torsional vibration damper in a high speed diesel engine)

  • 한영출
    • 오토저널
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    • 제4권1호
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    • pp.20-30
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    • 1982
  • Recent diesel engine has achieved high speed running comparable to that of gasoline engine as a speed improvement effort. Consequently, torsional vibration of high-speed diesel engine induced vibration nosise, reduced horsepower and the like. Viscous damper which is thought to be effective in curtailing the torsional vibration was studied over a wide range of speed. In this investigation, a water cooling, 4-cycle high-speed diesel engine(Msx. 3500 rpm)was used for the study. Theoretical analysis was made by assuming the engine to be an ideal equivalent system(length, moment of inertia) i. e. the multi-degree of freedom equivalent torsional vibration system with damper was analyzed. In the analysis, the inertia moment of suitable damper for this experiment was calculated by varying the relative damping coefficient of damper of engine for each damper. Furthermore, in the torsional vibration experiment, the torsional vibration amplitude of the crankshaft system was measured when the engine was equipped with dampers of different moments of inertia and also when the engine was equipped without dampers. The experimental results were compared with the analytical values and were found to be satisfied. The results of this investigation are summarized below; (1) It was found that for the engine equipped with dampers, the torsional vibration amplitude was reduced to about one third of those without dampers. (2) The optimum value of inertia moment of viscous damper for the engine was found to be about Id=1.05(kg.cm.s$^{2}$) (3) The optimum damping coefficient and the ratio of moment of inertia for the engine were found to be about Ca= 850(kg.cm.s), Rd=0.509, respectively (b1 dapmper).

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저속 장행정 박용디젤기관의 속도제어에 관한 연구 (A STUDY ON THE SPEED CONTROL OF A LOW SPEED-LONG STROKE MARINE DIESEL ENGINE)

  • 유영호;하주식
    • Journal of Advanced Marine Engineering and Technology
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    • 제12권4호
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    • pp.53-61
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    • 1988
  • Speed of a diesel engine is usually controlled by the hydraulic governor which uses the centrifugal force of rotating fly balls for sensing the error speed. But for a recently developed high efficient, low speed and long stroke 2 cycle marine diesel engine, this governor doesn't work well enough because of too much changes of toraring force during one revolution of engine and too long uncontrollable time due to small numbers of cylinder. For improvement of jiggling phenomena and unstability various studies are being carried out, but they are not enough for a steep load change in a small ship's generator plant or at rough sea condition in a propulsion engine. In this paper, authors propose a new method to control a fuel before the change of angular velocity due to load change by feedforward the change of load, and find that the proposed method shows quite a good control performance in comparision to the customary PID control method by simulation using a digital computer for the various load change.

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소형 고속 디젤기관의 배기 배출물에 미치는 배기 재순환율의 영향에 관한 실험적 연구 (An Experimental Study on Effects of EGR Rate upon Exhaust Emissions in Small High-Speed Diesel Engines)

  • 임재근;배명환;김종일
    • Journal of Advanced Marine Engineering and Technology
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    • 제16권4호
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    • pp.60-77
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    • 1992
  • The effects of exhaust gas recirculation(EGR) on the characteristics of exhaust emissions and specific fuel consumption have been investigated using an eight-cylinder, four cycle, direct injection diesel engine operating at several loads and speeds. The experiments in this study are conducted on the fixed fuel injection timing of $38^{\circ}$ BTDC regardless of experimental conditions. In conclusion, it is found that $NO_{x}$ emission is markedly reduced with the drop of burnt gas temperature at high speeds and loads especially as the EGR rate increases, while the soot particulate rises with EGR rate and load at a given engine speed, especially high loads. The reduction of exhaust emissions within the Korea heavy duty diesel engine emission standards can be roughly achieved by the optimal EGR rate without degarding the specific fuel consumption, based on the correlations between exhaust emissions.

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Multi-cavity Piston에 의한 바이오디젤유의 연소성 향상에 관한 연구 (The Study for Improving the Combustion of Biodiesel Fuel using Multi-cavity Piston)

  • 방중철;김용재;박철환
    • 한국연소학회지
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    • 제20권4호
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    • pp.26-33
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    • 2015
  • American NREL (National Renewable Energy Laboratory) reported that BD20 could reduce PM, CO, SOx and cancerogenic matters by 13.6%, 9.3%, 17.6% and 13% respectively, compared to diesel fuel. BD20 has been being tested on garbage trucks and official vehicles at Seoul City, which is positive on air environment, but negative on combustion by higher viscosity in winter season. This study investigated the combustion characteristics by employing multi cavity piston for improving the deterioration of combustibility caused by the higher viscosity of the biodiesel fuel such as BD20 with the combustion flames taken by a high speed camera and the cylinder pressure diagram. A 4-cycle single cylinder diesel engine was remodeled to a visible 2-cycle engine for taking the flame photographs, which has a common-rail injection system. The test was done at laboratory temperature of about $4{\sim}5^{\circ}C$.