Dual Injection PFI 2013

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TELKOMNIKA, Vol. 11, No. 4, April 2013, pp. 2141~2147e-ISSN: 2087-278X

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Received January 16, 2013; Revised February 26, 2013; Accepted March 6, 2013

Influence of Fuel Injection on Gasoline EnginePerformance

1Zong-zheng Ma,

2Xin-li Wang

1,2Department of Mechanical Engineering, Henan Institute of Engineering, Zhengzhou, China

*Corresponding author, e-mail: [email protected]

AbstractBecause of the most common method of preparing the fuel-air mixture for gasoline-

fueled engines is port fuel injection (PFI). For reducing the wall-film entering the cylinder in liquidphase, the phenomena of wall-film entering the cylinder in liquid phase should be at minimumlever or be avoided. So the first thing for learning the wall-film is to detect the way of the wall-film entering the cylinder. Therefore, the way of the wall-film enter the cylinder in liquid phase is

detected by changing the temperature of the wall-film location and time for wall-film evaporated.Then the way is validated by experiment test bed and it is improved that the way is feasible. Atthe end the influence of injection timing and fuel ratio on engine performance is studied basedon the test bed.The results show that regardless of the expansion stroke or the intake strokefuel injection the injection timing delay will decrese the engine power and make emissiondeterioration meanwhile the twice fuel injection can improve the fuel film evaporation resulting ofhigh-speed airflow of intake charge.

Keywords: gasoline engine; wall-film; body temperature; fuel evaporation

Copyright 2013 Universitas Ahmad Dahlan. All rights reserved.

1. Introduct ionCurrently, the most common method of preparing the fuel-air mixture for gasoline-fueledengines is port fuel injection (PFI) [1, 2]. For the car gasoline engine, especially for cold start orwarm-up phase, the fuel deposited directly in the intake port can be problematic when the intakevalve and port walls are not sufficiently warm [3,4]. The liquid fuel spray of 30or larger droplethits on the wall of the intake port and the surface of the intake valve which caused fuel wettingand fuel liquid film flowed into the cylinder without vaporized [5]. The more worse is that neithercompression heating nor combustion completely vaporizes liquid fuel films in the combustionchamber [6]. Therefore, the high HC emissions of the engine should be concerned and muchmore researchers have done to reduce the HC emission during cold start and warm-up phase[7-9].

Compared to car engines, motorcycle engines tend to have lower displacementvolumes and the need for high specific output power make it operating at high revolution

speeds. So for motorcycle gasoline engine with PFI system, the wall-film thickness is high andwall-film area is small because of compact structure and low injection pressure (250kPa-300kPa), the time of the fuel evaporation is short because of high speed. Therefore, the wall-film on the back of the intake valve and intake-port may be not evaporated completely and enterthe cylinder in liquid phase which would cause high fuel consumption and HC emission.

For reducing the wall-film entering the cylinder in liquid phase, the phenomena of wall-film entering the cylinder in liquid phase should be at minimum lever or be avoided. So the firstthing for learning the wall-film is to detect the way of the wall-film entering the cylinder. Basedon traditional theory the ways for wall-film entering the cylinder include two ways: first, theinjected fuel keeps dynamic equilibrium which means there is some fuel in the intake-port withwall-film phase but the injected fuel and the wall-film entering the cylinder in vapor phase isequivalent; the second way is the wall-film entering the cylinder in liquid phase which means thewall-film can not vaporized before the intake valve closing and when the intake valve opens

again the fuel strip off the wall and enter the cylinder in liquid phase. The two ways of the wall-


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e-ISSN: 2087-278X

TELKOMNIKA Vol. 11, No. 4, April 2013 : 2141 2147

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film entering cylinder is opposite so the detecting whether the wall-film entering the cylinder isemphasized.

2. Scheme of the Experiment

When the fuel injected stays dynamic equilibrium the air-fuel ratio can not be changed ifthe evaporation rate of the wall-film is changed. Meanwhilewhen evaporation rate of the wall-film is accelerated, the air-fuel ratio would be deceased and HC emission would be improved ifthe wall-film enter the cylinder in liquid phase. Yet for the fixed speed, throttle opening angleand injected fuel the wall-film evaporation rate can be affected by temperature of the wall-filmlocation, time for wall-film evaporated and intake flow intensity. Therefore, the way of the wall-film enter the cylinder in liquid phase is detected by changing the temperature of the wall-filmlocation and time for wall-film evaporated.

3. Test equipment and test methodsThe test bed consists of K157 FMI engine (specific parameters shown in Table 1),

electric eddy current dynamometer, dynamometer control system, gasoline engine ECU, speedy

data collection system, five gas analyzer (specific parameters shown in Table 2), wide-bandoxygen sensor and computer. The bed is shown in Figure 1, where the electric eddy currentdynamometer and dynamometer control system are used to control and measure the load of theengine, engine fuel injection system are used for controlling timing of fuel injection and ignition,and the computer's serial communication can be used to control gasoline engine ECU as tocontrol fuel injection and ignition.

Table 1 Parameters of the K157 FMI Table 2 Five Gas Parameters AnalyzerParameter Value Parameter Range Resolution Error

type Single, four-stroke HC(10-6) 0-10000 1 12

Bore x stroke (mm) 56.549.5 CO(%) 0.00-10.00 0.01 0.06

displacement /L 124 CO2(%) 0.00-20.00 0.1 0.5Compression ratio 9 1 O2(%) 0.00-25.00 0.1 0.1Cooling style wind cooling NOx(10-6) 0-5000 1 25

Figure1. Diagram of Experimental System

4. Selection of Reference Temperature Point of the EngineFor the intake-port fuel injection engine, the temperature of the wall-film area determine

As we all known that the motorcycle is cooled by air and the temperature of this pint can beeasily affected by cooling condition since the surface temperature is changed more easily thaninner temperature for the engines specific heat capacity. But the inner temperature of the

engine is hard to measure and the thermodynamic state is can be valued by surface


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TELKOMNIKA e-ISSN: 2087-278X

Influence of Fuel Injection on Gasoline Engine Performance (Zong-zheng Ma)

2147

From the above analysis it is shown that the twice fuel injection technology shouldutilize the intake flow for improving fuel evaporation. So the fuel needs to be fitted with the high-speed airflow, the intake stroke fuel injection amount should not be excessive. Otherwise, if thefuel injection time is too long the intake airflow with the interaction effects between the fuels isweakened for the airflow velocity decreases which will reduce the fuel evaporation rate and

affect engine performance.

7. ConclusionBased on the research it can be included in follows:

1) Under cooling condition it is hard to value the engine thermodynamic state with only onemeasure point.

2) The way of the wall-film enter the cylinder in liquid phase can be detected by changing thetemperature of the wall-film location .

3) When the engine is in a small throttle opening angle, regardless of the expansion stroke orthe intake stroke fuel injection, the injection timing delay will reduce the film evaporation,then decrese the engine power and emission deterioration.

4) When using twice fuel injection technique, the fuel injection amount should not be

excessive for intake stroke injection for high-speed airflow.

AcknowledgementThis work was supported by the Technologies R & D Program of Zhengzhou (Grant

Nos. 121PPTGG357-8) and Henan institute of engineering doctor foundation (D2012011).

References[1] Hang Zhu, Shaoguang Wang. Calibration for Characteristic Parameters of Fuel Film in Intake Duct of

EFI Gasoline Engine.Automotive Engineering. 2004; 26: 127-130.

[2] Hongzhi Zhao, Lin Cao. A Study on EGR Performance of CA6102 Electronically-controlled GasolineEngine,Automotive Engineering., 2005; 27: 264-268.

[3] Witze PO, Green RM. LIF and Flame-Emission Imaging of Liquid Fuel Films and Pool Fires in an SIEngine during a Simulated Cold Start. SAE Paper. Detroit, MI, USA. 1997; 1: 101-103.

[4] Yukihiro Takahashi, Yoshihiro Nakase. Analysis of the Fuel Liquid Film Thickness of a Port FuelInjection Engine.SAE Paper, Detroit, MI, USA. 2006; 1: 245-248.

[5] Kimitaka Saito, Kiyonori Sekiguchi, Nobuo Imatake. A New Method to Analyze Fuel Behavior in aSpark Ignition Engine.SAE Paper. Detroit, MI, USA. 1995; 1: 453-458.

[6] Nemecek LM, Wagner RM, et al. Fuel and Air Studies for Spark Ignition Engine Cold StartApplications. Proceedings of ILASS. America. 2000; 1: 132-139.

[7] Cho H, Min K. Measurement of liquid fuel film distribution on the cylinder liner of a spark ignitionengine using the laser-induced fluorescence technique. Measurement Science and Technology, 2003;14: 975-982.

[8] SK Fulcher, BF Gajdeczko, PG Felton, et al. The Effects of Fuel Atomization, Vaporization, and Mixingon the Cold-Start UHC Emissions of a Contemporary S.I. Engine with Intake-Manifold Injection.SAEPaper. Detroit, MI, USA. 1995; 1: 235-242.

[9] Zughyer J, Zhao FQ, Lai MC, et al. A Visualization Study of Fuel Distribution and Combustion inside aPort-Injection Gasoline Engine under Different Start Conditions.SAE Paper.Detroit, MI, USA. 2000; 1:127-134.

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Dual Injection PFI 2013