• Journal of Biosystems Engineering
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• 제35권4호
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• pp.239-243
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• 2010

Biodiesel (BD) can be effectively used as an alternative fuel in diesel engines. However, BD may affect the performance and exhaust emissions in diesel engines because it has different physical and chemical properties from diesel fuel such as viscosity, compressibility and so on. To investigate the effect of injection timing on the characteristics of engine performance and exhaust emissions with BD in an indirect injection diesel engine, BD derived from soybean oil was applied in this study. The engine was operated at six different injection timings from TDC to BTDC $12^{\circ}CA$ and five loads at various engine speeds. Below BD 30, there's similar trend compared with diesel fuel. But, the best injection timing was $4{\sim}6^{\circ}CA$ retarded compare with diesel fuel using BD 30. When the fuel injection timing was retarded, better results were showed, which may confirm by advantages of BD.

• 한국자동차공학회논문집
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• 제13권2호
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• pp.44-51
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• 2005

According to the increasing concern on the global environment, the $CO_2$ regulation has been discussed including automobile emission regulation. In order to cope with this rapid changing circumstances, the development of an ultra low emission and super fuel economy automobile is essential. Direct injection LPG engine is the one of the possible future engine to maximize the engine efficiency. This experimental study for the development of direct injection LPG engine technology is promoted with two parts; spray characteristics of high pressure swirl injector, and performance characteristics of direct injection LPG engine. Engine characteristics according to the fuel was analyzed in order to establish stratified combustion technology for LPG engine by using the DISI engine. In the engine experiment, control system was manufactured for gasoline and LPG fuel. The engine was modified 2,000 cc GDI engine (fuel supply device, fuel injection device). Through this experiment, engine operating condition, engine speed and spark timing (MBT), fuel injection position, and fuel rate were investigated.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.30-37
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• 2004

The combustion and emission characteristics of a direct injection CI engine fuelled with DME(Dimethyl Ether) and diesel fuel were compared at idle engine speed(800 rpm) with various injection parameters. An optical single cylinder diesel engine equipped with a common-rail fuel injection system was constructed to investigate combustion processes of DME and diesel fuel. The combustion images were recorded with a high-speed video camera system. The results demonstrated that the DME-fuelled engine was superior to the conventional diesel engine in terms of engine performance and emissions. The optimal injection timing of DME was located around IDC(Top Dead Center), which was roughly same as that of diesel fuel. As the injection timing was advanced much earlier than TDC, NOx (Nitric Oxides) level increased considerably. NOx emission of DME was equal or a little higher than that for diesel fuel at the same injection pressure and timing because of higher evaporation characteristics of DME. Throughout all experimental conditions, DME did not produce any measurable smoke level.

• 한국분무공학회지
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• 제9권1호
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• pp.30-36
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• 2004

The purpose of this study was to investigate the fuel spray characteristics that made most important at an homogeneous air fuel mixture, in a common rail direct injection type HCCI engine. As a study conducted relation which a back pressure and injection pressure are influenced to air fuel mixture characteristics, we tried to offer date even through we select suitable to a HCCI engine running condition of the fuel injection condition. To accomplish the study, to measure a injection rate of common rail type injector and to visualize and simulate a fuel spray was conducted. From the result of injection rate, a common rail injector was confirmed to appear a initial delay of 0.3msec and a latter period delay of 0.7msec. Therefore, real injection duration was determined by about 0.5msec increasing. From the result of fuel spray, the spray penetration was proportional to 1/4 exponent of atmosphere pressure. An experimental equation was deduced from the spray penetration of spray visualization experiment and the relation of injection duration and penetration was estimated in HCCI engine using an experimental equation.

• 한국분무공학회지
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• 제13권1호
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• pp.1-8
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• 2008

It was investigated how fuel injection timing - early injection and later injection - in conjunction with throttle open rate effect the fuel-air mixing characteristics, Engine power, combustion stability and emission characteristics on a DI CNG spark Engine and control system that had been modified and designed according to the author's original idea. It was verified that the combustion characteristics were changed according to fuel injection timings and Engine conditions determined by different throttle open rates and rpm. It was found that the combustion characteristics greatly improved at the complete open throttle rate with an early injection timing and at the part throttle rate with a late injection timing. Combustion duration was governed by flame propagation duration in a late injection timing and by an early flame development duration in an early injection timing. As the result, we discovered that combustion duration is shortened, lean limit is improved, air-fuel mixing conditions controlled, and emissions reduced through control of fuel injection timing according to change of the throttle open rate.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.76-82
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• 2004

Biodiesel fuel(BDF) which is easily produced from vegetable oils such as soybean oil and rice bran oil can be effectively used as an alternative fuel in diesel engine. However, BDF can affect the performance and emissions in diesel engine because it has different chemical and physical properties from diesel fuel. To investigate the effects of injection timing on the characteristics of performance and emissions with BDF in IDI diesel engine, BDF derived from rice bran oil was considered in this study. The engine was operated at six different injection timings and six loads at a single engine speed of 2000rpm. When the injection timing was retarded, better results were obtained, which may confirm the advantage of BDF. The reduction of NOx and smoke was observed for a 2$^{\circ}$ retarded injection timing without any sacrifice of BSEC.

• 한국분무공학회지
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• 제12권2호
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• pp.108-114
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• 2007

This study investigates the influence of energizing duration on the fuel atomization characteristics of biodiesel injected through a high pressure common-rail injector. In order to analyze the effect of energizing duration on the fuel injection rate performance, the injection rate of biodiesel fuel is obtained from the pressure variation in the tube filled with fuel in injection measuring system. On the other hand, the atomization characteristics of biodiesel was measured and compared in terms of Sauter mean diameter(SMD), arithmetic mean diameter(AMD), droplet mean velocity, and detected droplets number by applying a phase Doppler particle analyzer(PDPA). It was revealed that the injection mass and maximum injection rate increase with increase of the energizing duration. Moreover, the increase of energizing duration improves the atomization performance of biodiesel fuel because it induces higher droplets momentum and velocity.

• 한국분무공학회지
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• 제24권4호
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• pp.171-177
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• 2019

This paper describes numerical study of combustion characteristics in CNG(compressed natural gas) DI(direct injection) engine using gaseous sphere injection model. Simulations were conducted using KIVA-3V Release 2 code. Gaseous sphere injection model, which is modified model of liquid fuel injection, was used to simulate the CNG direct injection. Until now, a very fine mesh smaller than the injector nozzle has been required to resolve the gas-jet inflow boundary. However, the gaseous sphere injection model simulates gaseous fuel injection using a coarse mesh. This model injects gaseous spheres as in liquid fuel injection and the gaseous spheres evaporate together without the latent heat of evaporation. Therefore, it does not require a very fine mesh and reduce calculation time. Combustion simulation were performed under various injection timings and injection pressures.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.144-152
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• 1996

In the sequential MPI system with one injection for each cycle, engine performance is influenced by the mixture conditions. It can be said that engine performance is improved by being better identical mixture formation conditions for all cylinders. As the fuel injection timing to the intake port effects on the mixture formation conditions and the engine performance, injection timing must be better adjusted to engine requirements. Engine behavior was clearly different depending on the injection time during intake storke. Therefore it was studied that injection timing of fuel effects on the engine performance I. e. combustion stability, COV(imep), A/F excursion, CO,HC emission concentration and fuel consumption. It was found that late intake-synchronous injection was deteriorated the combustion characteristics and performance characteristics, while early intake-synchronous infection resulted in favorable engine behavior.

• 한국분무공학회지
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• 제6권1호
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• pp.1-8
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• 2001

Fuel injection system is very important in diesel combustion. Recently electronic control of fuel injection system and common rail systems are introduced to reduce the emission and to increase the energy efficiency from diesel engine by control of the injection timing and duration. In this study, evaluation possibility of the system for electronic control by spool valve, one of the accumulator type injection systems with spool valve using solenoid was composed and the operating characteristics were investigated to evaluate the effects of spring coefficient, initial spring force, solenoid driving time, fuel supply pressure on the injection timing and duration. We could confirm the capability that diesel injection was electronically controlled by spool valve.