Analysis of fuel injection parameter on biodiesel and diesel spray characteristics using common rail system

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Analysis of Fuel Injection Parameter on Biodiesel and Diesel Spray

Characteristics using Common Rail System

KHALID Amir

' l a ,

SAPIT ~ z w a n ' ,

M.N. ~ n u a r ' , HIM ~ a m s y ' ,

MANSHOOR

~ukhari',

ZAMAN lzzuddin2, NGALl zamani2

'~utomotive Research Group (ARG), Centre for Energy and Industrial Environment Studies (CEIES), Universiti Tun Hussein Onn Malaysia, Parit Raja, Batu Pahat, 86400 Johor, Malaysia

2Universiti Tun Hussein Onn Malaysia, Parit Raja, Batu Pahat, 86400 Johor, Malaysia. "amirk@uthm.edu.my, bnorrizam@uthm.edu.my

Keywords: Diesel Spray, mixture formation, common rail system, optical visualization

Abstract. Precise control of fuel injection is essential in modern diesel engines especially in

controlling the precise injection quantity, flexible injection timing, flexible rate of injection with multiple injections and high injection pressures. It was known that the fuel-air mixing is mainly influenced by the fuel injection system and injector nozzle characteristics. Thus, mixture formation during ignition process associated with the exhaust emissions. The purpose of this study is to investigate the influence of spray characteristics on the mixture formation. In this study, common rail injector systems with different model of injector were used to simulate the actual mixture formation inside the engine chamber. The optical visualization system was constructed with a digital video camera in order to investigate the detailed behavior of mixture formation. This method can capture spray penetration length, spray angle, spray evaporation and mixture formation process clearly. The spray characteristic such as the penetration length, spray angle and spray area are increasing when the injection pressure increased. The mixture formation can be improved effectively by increasing the injection pressure.

Introduction

Diesel engine is an internal combustion engine that uses the high compression pressure to ignite the combustible mixture due to high temperature in the combustion chamber. However, current diesel engine still suffered the emission problems such as nitrogen oxide (NOx) and particulate matter (PM) into the atmosphere. It is well known that the hel-air mixture formation is responsible for ignition of diesel engines. Hence, effectively control mixture formation is important to improve the exhaust emission from diesel engine [I-51. In diesel engine, common rail systems employ injector in order to control the fuel injection event. This injector increases the performance and fuel economy of diesel engines. In order to control the sufficient combustion process, a lot of researches were respecting both energy-conservation requirements and coming tougher emissions regulations

[6-81. It is well known that the rapid compression machine is an excellent tool to study high pressure auto-ignition of combustible mixtures as it gives a direct measure of ignition delay 191. In common rail system, the high pressure will accumulate fuel in the common rail and quantities of fuel injected into the engine cylinder are controlled by the Electronic Control Unit (ECU). The high-pressure injection controlled by the ECU is independent of the engine speed and load. As a result, the common rail system can reduce exhaust emissions such as nitrogen oxides (NOx) and particulate matter VM) simultaneously generates more engine power [lo-121. Due to the legislation on emissions from becoming stricter, common rail diesel engine should be continued to further develop its injection systems and engine performance to meet the kture requirements.

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Experimental Setup

Figure 1 shows the schematic diagram of common rail which consist four components including pump, fuel rail, Electronic Control Unit (ECU) and injector. As seen in Fig 1, the channels of fuel to move in and out in each component. The Beige channel indicated that the he1 is in low pressure, red channel indicated that the he1 is in high pressure and pink channel indicated that he1 is in medium pressure. Table 1 summarizes the FMI-1000 Common Rail Injector system was used to simulate the common rail injection system with a constant pressure condition similar to actual diesel engine The fuel pressure in the accumulator can increase up to 180 MFa by using a pump. The fuels tested were a grade I1 diesel (Standard hesel-STD) and blends of B5, B10 and B15 palm oil with the diesel fuel and the particulars of the tested fuels are detailed in Table 2. Three injectors such as Denso, Bosch and Delphi, and the specifications of the injector are listed in the Table 3. All the injectors were driven by a solenoid and used to inject biodiesel and JIS#2 diesel fuel (a density of 836kg/m3 and

lower heating value of 42 7MJlkg) into the spray chamber

The real spray image will be obtained by using direct photography method. This method can capture spray penetration length, spray angle, spray evaporation and mixture formation process clearly. he mixture formation and spray development of fuel injection from the nozzle tip will be observed with the real time changes. All the penetration length, spray angle and spray area of fuel injection from the spray image will be evaluated. The smaller the fuel particles, the well atomizes of fuel. The image of a spray will be compared with term of injection penetration, spray angle and spray area at different type of injector

Figure 1 Schematic diagram of common rail system apparatus

Table 1 : Common rail specification Table 2: Biodiesel Properties

Fuel Density

Type (dcm3)

STD 0.833736 B5 0.837048 B10 0.837664

Fuel Properties

Kinematic

91.5 120.1 2.9 92.0 158.6

--

(Centipoises, I cP = 0.000001 m2/s, Parts per million, lppm = 0.0000001mg/kg)

Experimental Results

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and B15. It seems that Denso injector spray more amount of fuel quantity compared to the Bosch and Delphi injector even though the pressure is increased. The lesser fuel is injected by Bosch injector. Furthermore, the graphs also show the quantity of fuel injected by each type of injector at different type of fuel such as diesel, B5, B10 and B15 are almost similar to each other. It can be concluded that the different type of he1 such as B5, B10 and B15 did not larger affect the performance of injector to deliver hel.

Figure

*

-

&

--

Diesel

40 60 80 100 40 60 80 100

"

Pressure (MPa) Pressure (MPa)

Fuel quantity for variant in injection pressure, fuel injector and biodiesel blending ratio

Figure 3 Real images of diesel spray at 40 MPa

Injector

Figure 4 Real images of diesel spray at 60 MPa

Time (s) I

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constant injection pressure compared to other type of injector. However, the spray images of the Delphi injector became disorderliness when the injection pressure increased. In the image, the spray angle and spray area of Delphi injector are also larger and broader than other type of injector when injection pressure increases. The spray images of Bosch injector show moderation characteristics between the Denso and Delphi injector.

Figure 5 Real images of diesel spray at 80 Mpa Figure 6 Real images of diesel spray at 1 OOMPa

Next, this study attempt to use image analysis technique to investigate the mixture formation behavior with the time changes. Figure 6 depicts the variation in spray characteristics such as spray penetration length and spray angle that extracted from the Fig. 3, Fig.4, Fig.5 and Fig. 6. As seen in the Fig. 7, diesel spray obtained from Delphi injector has a larger penetration length compared to the other injector. However, Denso injector has the shorter penetration length in the figure. Moreover, it can be seen that the penetration length of Bosch and Delphi injectors are increased when the pressure is increased. At 80 MPa and 100 MPa, the penetration length of Bosch and Delphi are almost similar to each other. However, the penetration length of Denso injector has a minor increase in pressure. After compared to the experimental results of each injector, the Denso injector shows a larger spray angle at low pressure, but it shows a smaller spray angle at high pressure. However, the Delphi injector shows inverse characteristics compared to the Denso injector.

All

the injectors have a similar spray angle at 80 MPa injection pressure. By evaluating the spray development, we find that the spray angle is fast expanding in the first 0.1 second and increased slowly after that.

0.0

O.' T m (s) 0.2 a3 0.0 0.1 T i m (s) 0.2 0.3

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Conclusions

This research investigated on the effects of &el injection parameter on diesel spray characteristics. The experiment was carried out using the common rail injector system and spray characteristics were analyzed in detail using the spray visualization system with a digital video camera. The conclusions of this research are summarized as follows.

1. Increased injection pressure thus predominantly influences the increasing of the penetration length, spray angle and spray area especially under Denso injector. However, Delphi injector has a larger penetration length compared to the Denso injector which has shorter penetration. 2. Denso injector shows a larger spray angle at low pressure and smaller spray angle at high

pressure, the Delphi injector shows inverse characteristics to the Denso injector. The spray areas o f these three types of injectors are similar to each other at four constant pressures.

Acknowledgement

The authors also would like to thank the Ministry of Higher Education Malaysia for supporting this research under the COE-MTUN Grant Scheme VOT.CO09 and Research Acculturation Grant Scheme (RAGS) Vot. R025.

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Figure

Figure 1 Schematic diagram of common rail system apparatus

Figure 1

Schematic diagram of common rail system apparatus p.2
Table 1 : Common rail specification

Table 1 :

Common rail specification p.2
Figure Fuel quantity for variant in injection pressure, fuel injector and biodiesel blending ratio

Figure Fuel

quantity for variant in injection pressure, fuel injector and biodiesel blending ratio p.3
Figure 3 Real images of diesel spray at 40 MPa

Figure 3

Real images of diesel spray at 40 MPa p.3
Figure 7 Penetration length and spray angle for diesel fuel

Figure 7

Penetration length and spray angle for diesel fuel p.4
Figure 5 Real images of diesel spray at 80 Mpa

Figure 5

Real images of diesel spray at 80 Mpa p.4

References