a review on study of single fuel combustion system and duel fuel combustion system

2049

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Published On: February 29, 2016

International Journal of Informative & Futuristic Research ISSN: 2347-1697

Volume 3 Issue 6 February 2016 Reviewed Paper

Abstract

Smoke is decreased and NOx is increased with advanced pilot injection timing in the (biodiesel–CNG) Duel Fuel Combustion system. Compared to the diesel SFC, however, smoke emissions are significantly reduced over the range of operating conditions and NOx emissions are also reduced except for the full load condition. DFC yields lower CO2 emissions compared to diesel SFC over all engine conditions. Biodiesel–CNG DFC results in relative high CO and HC emissions at low load conditions due to the low combustion temperature of CNG but no notable trend of HC emissions with variations of pilot injection timing were discovered. The duel fuel combustion DFC can give good results of combustion and significant improvement in performance and reduction in emission than the single fuel combustion SFC. This study instigates the duel fuel combustion system over the single fuel combustion system

A Review On Study Of Single Fuel

Combustion System And Duel Fuel

Combustion System Paper ID IJIFR/ V3/ E6/ 030 Page No. 2049-2055 Subject Area

Mechanical

Engineering

Keywords Dual fuel combustion (DFC), Single fuel combustion (SFC), Biodiesel, CNG.

1st Murade Akash R

TE Mechanical ,

Shri Saibaba Institute Of Engineering Research And

Allied Sciences, Rahata-Maharashtra

2nd Laware Pratik R.

M.E. Student,

Department Of Mechanical Engineering

Padmashri Dr. Vitthalrao Vikhe Patil College Of

Engineering , Ahmednagar Maharashtra

3rd Laware Monali R

SE Mechanical



4th Kale Adesh S.

TE Mechanical



http://www.ijifr.com/

2050

ISSN: 2347-1697

International Journal of Informative & Futuristic Research (IJIFR)

Volume - 3, Issue -6, February 2016

Continuous 30th Edition, Page No.:2049-2055

Murade Akash R, Laware Pratik R., Laware Monali R, Kale Adesh S.

:: A Review On Study Of Single Fuel Combustion System And Duel Fuel Combustion System

1. INTRODUCTION

Due to shortage of fossil fuels, various studies on internal combustion engines using

alternative fuels to protect the global environment and to conserve energy have been

undertaken in recent years. Research has particularly focused on diesel engines, utilizing

high thermal efficiency to improve both performance and emissions. However, diesel

engines still have a major problem with the simultaneous reduction of NOx and smoke

due to governing combustion mechanisms. Many studies have developed new methods

for reducing the exhaust emissions by avoiding the combustion regions where NOx and

smoke are mainly generated [1, 2]. The dual fuel combustion concept was utilized by

many researchers. With port injection of a low-reactivity fuel combining direct in-

cylinder injection of a high-reactivity fuel, the combustion phasing and duration can be

flexibly controlled through reactivity gradient. Early in the development of the diesel

engine, the concept of operating on gaseous fuels with pilot oil ignition was recognized.

Dr. Rudolf Diesel was granted a patent in 1898 for his method consisting of the injection

of a liquid fuel to start the combustion of the working mixture of a gaseous fuel and air

in the engine cylinder. However, the dual fuel commercial development only goes back

to the late 1930's when a stationary dual fuel engine fuelled with town gas was produced

and operated in England [3, 5]. Biofuels are derived from biomass, and are renewable

either through agricultural processes (i.e. growing corn for ethanol) or biological waste

generation (i.e. animal waste products). Biofuels can be used in any diesel engine,

usually without any modifications. It boasts a reduction in toxic emissions (except NOx

emissions) compared to diesel fuel [6].In this study, based on these preceding studies,

the effects of pilot injection timing on combustion and exhaust emissions characteristics

were investigated with a biodiesel–CNG DFC system in a single cylinder diesel engine.

Biodiesel produced from used vegetableoil was used as a pilot injection fuel to ignite the

CNG, which was the main fuel charge used in this study.[2] Although natural gas has

various advantages to use in automobile engines there are many challenges in using

natural gas in diesel engine application due to a very high auto-ignition temperature

which requires a high energy source such as spark plug or pilot injection to achieve

ignition. Thus CNG has been mainly used in spark ignition engine applications,

however, based on the propertiesof CNG it is best utilized in high compression ratio

engine applications. Therefore, CNG would be best utilized in diesel engine

applications. CNG presents a promising prospect in duel fuel combustion (DFC)

operation with pilot injection as an ignition source to increase thermal efficiency while

simultaneously reducing exhaust emission in diesel engines. DFC systems are

particularly promising because no cylinder chamber modifications are necessary in the

implementation process. Dual fuel engines are capable of reducing both PM and NOx to

levels significantly lower than that of traditional diesel engines. The main scope of the

present study is to evaluate the performance, emission and combustion characteristics of

biofuel and Addition of diesel with biofuel in a diesel engine. Biofuel can be used as a

neat fuel for diesel engine since their properties are similar to diesel fuel. Many

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researchers are revealed that the emissions from biofuel fuelled diesel engine give lesser

CO, HC, PM and higher NOx. There are different techniques such as blending; water

injection and EGR can be used to reduce NOx emissions in diesel engines [6, 2].

2. EXPERIMENTAL SETUP AND CONDITIONS

In order to investigate the effects of pilot injection timing in a diesel engine with a

biodiesel-CNG DFC system, a single cylinder diesel engine coupled with a

dynamometer was used in this study. The detailed experimental system and test

conditions are given as follows.

2.1 Experimental setup

Figure1. Schematic diagram of experimental apparatus [11]

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Table -1: Properties of pilot fuel and main fuel for duel fuel diesel engine

S.N. Item Diesel Biodiesel CNG

1. Flash point (PM, 0C) 72 78 -

2. Kinematic viscosity (40 0C,mm

2/s) 2.52 4.2 -

3. Sulfur (mg/kg) 8 1 -

4. Cetane index 51.4 54< -

5. Density (15 0C, kg/m

3) 826 882 -

6. Low Heating values (kJ/kg) 43.116 x103 40.001 x10

3 45.8 x10

3

7. Content of C (%) 84.15 78.11 -

8. Content of H (%) 14.6 12.79 -

9. Content of O (%) 0.25 9.1 -

10. Net heating value (kJ/N m3) - - 43.58 x10

3

11. Specific gravity (compare to Air) - - 0.55

12. Burning range (%) - - 5–15

13. Ignition temperature (0C) - - 580

14. Methane (Vol.%) - - 85.12

15. Ethane (Vol.%) - - 9.32

16. Propane (Vol.%) - - 0.58

17. i-butane (Vol.%) - - 0.56

18. n-butane (Vol.%) - - 0.42

19. Nitrogen (Vol.%) - - 0.01

These characteristics have studied under the consideration of single fuel as well as duel

fuel, while for single fuel combustion there is diesel is a reputed fuel but the DFC duel

fuel combustion we can use CNG with diesel and also the CNG with biodiesel. In this

CNG is a main fuel and other is a pilot fuel used for igniting the compressed charge of

gas.

3. RESULTS AND DISCUSSIONS

16

Diesel Engine speed : 1800rpm

[M

Pa

]

12 Biodiesel Injection Pressure : 120 MPa

Diesel-CNG Engine Load : 75%

Biodiesel-CNG Start of injection : BTDC 17oCA

8

160

Pre

ssu

re

Re

lea

seH

eat

4 120

0 80

40

Ra

te[J

/CA

]

0

-40 -20 0 20 40 60

Crank Angle [ºCA] (a) (b)

Figure 2: Comparison of combustion characteristics between single fuel combustion

and dual fuel combustion at an engine speed of 1800 rpm and an engine load of

75%: (a) cylinder pressure and heat release rate, (b) mass fraction burned.

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The biodiesel–CNG DFC compared to conventional SFC and diesel–CNG DFC

at an engine load of 75% and engine speed of 1800 rpm. The case of 75% engine load is

chosen as a representative of the combustion characteristics observed throughout the

study. It is found that the peak cylinder pressure for DFC is slightly lower and occurs

later than SFC. It is seen that the pilot fuel ignites approximately 2.0–3.0 CAD later than

the normal SFC event. It can be explained by CNG inducted during the intake process

leading to the lower in-cylinder temperature, thus lengthening the ignition delay of the

pilot fuel. One possible explanation is that the cooling effects of CNG resulting in low

in-cylinder temperature overcome the high cetane number and cause slow ignition

speed. And the high injection pressure has a much greater effects to vaporize and ignite

the pilot fuels at the presence of CNG premixed, resulting in low in-cylinder temperature

[2, 8].It is also believed that due to biodiesel’s lower lower heating value and higher

kinematics compared to diesel results in increased difficulty of the pilot fuel to energize

the combustion of the main CNG charge. It is studied that with increased engine load,

the ignition delay of biodiesel–CNG DFC can be reduced by approximately 1.6–4.4

CAD by delaying the pilot injection timing. It is also found that the maximum difference

of ignition delay between the various pilot injection timings are reduced as the engine

load increases. [2] The BSEC of SFC and DFC according to the increase of engine load

and an injection timing of 17 CAD BTDC. It is noticed that the BSEC of DFC are

generally higher than those of SFC, which is due to the lower volumetric efficiency of

duel fuel modes. In the case of DFC, it is also found that the BSEC of biodiesel–CNG

DFC is slightly higher than those of diesel–CNG DFC. This can be attributed to the

reduced lower heating value of biodiesel compared to diesel.

3.1 The emission characteristics

As the k.ryu- states smoke emissions of diesel SFC and biodiesel–CNG DFC according

to the variation of pilot injection timing. It is found that smoke emissions for DFC are

significantly reduced compared to the diesel SFC. It is considered that the biodiesel pilot

fuel is mainly associated with the smoke emissions because CNG combustion consisting

of mainly methane does not produce particulate. The NOx emissions of diesel SFC and

biodiesel–CNG DFC according to the variation of pilot injection timing. It is found that

compared to diesel SFC, NOx emissions of biodiesel–CNG DFC are relatively low at

the low to medium load range but are higher at high load conditions. This validates the

idea that the simultaneous reduction of smoke and NOx can be achieved with biodiesel–CNG DFC except in the full load case. For the DFC of diesel with CNG is due to the

lack of oxygen, the combustion is incomplete in the over rich region of mixture so which

result in higher CO formation. But the bio fuel contains oxygen so there is reduction in

CO formation of duel fuel combustion. In table no.1 the percentage contains in bio

diesel is 9.1 % of oxygen so it results the better combustion of mixture and reduction in

emission.

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Figure 3:Smoke emissions of diesel single fuel combustion and dual fuel combustion at an

engine speed of 1800 rpm and at a pilot injection pressure of 1200 Bar.

variation of unburned hydrocarbons with brake power for biofuel, diesel and their

blends. It is seen that neat biofuel operation emits lower UHC compared to all other

fuels. The amount of oxygen participates during combustion will increase the oxidation

process. There is more oxygen chemically bounded with oxygen in biofuel which is an

additional source of oxygen other than oxygen present in the intake air. This oxygen

helps for the formation of air fuel mixture and it takes part in complete combustion. The

intensity of UHC in the exhaust gas increase as the quantity of diesel increases in the

blend is due to less quantity of oxygen in the blend.

It is observed that DFC yields lower CO2 emissions for all operating conditions when

compared to diesel SFC. It is considered that this result is caused by more complete

combustion in SFC. It is also found that for DFC, CO2 emissions increases with both

increased load and advanced pilot injection timing. This can also be explained by more

complete combustion.

4. CONCLUSION

In this study the DFC duel fuel can gives significant improvement in performance and

reduction in emission than the single fuel combustion SFC. The main conclusion is that

the emission characteristics of diesel engine or compression ignition by employing the

biodiesel pilot fuel and the main fuel is CNG natural gas which can gives good

combustion characteristics by improving pilot fuel timing. Some of the topics concluded

from this investigation are as follow:

Exhaust gas temperature is lower with neat biofuel and CNG as compared to

diesel due to early combustion. The exhaust temperature increases with increase

in quantity of diesel in the biofuel–CNG.

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UHC and CO emissions are found to be very low with DFC duel fuel

combustion. Increase in UHC and CO emission is noticed with diesel or SFC

single fuel combustion.

The NOx emission is increaseas the pilot injection timing is advanced for

biodiesel–CNG DFC. Compared to diesel SFC, however, smoke emissions are

significantly reduced over the range of operating conditions and NOx emissions

are also decreased over the range for the exception of the full load case.

DFC yields lower CO2 emissions compared to diesel SFC over therange of

operating conditions. Biodiesel–CNG DFC results in relativehigh CO and HC

emissions at low load conditions due to thelow combustion temperature of CNG.

5. REFERENCES [1] Su Han Park, Seung Hyun Yoon, Chang Sik Lee, “Effects of multiple-injection

strategies on overall spray behavior, combustion, and emissions reduction characteristics

of biodiesel” fuel Applied Energy 88 (2011) 88–98

[2] Kyunghyun Ryu-Effects of pilot injection timing on the combustion and emissions

characteristics in a diesel engine using biodiesel–CNG dual fuel Applied Energy 111

(2013) 721–730

[3] Jie Liu, Fuyuan Yang, Hewu Wang, Minggao Ouyang, Shougang Hao-“Effects of pilot

fuel quantity on the emissions characteristics of a CNG/diesel dual fuel engine with

optimized pilot injection timing” Applied Energy 110 (2013) 201–206

[4] N. Ravi Kumar, Y. M. C. Sekhar, and S. Adinarayana- “Effects of Compression Ratio

and EGR on Performance, Combustion and Emissions of Di Injection Diesel Engine”

International Journal of Applied Science and Engineering 2013. 11, 1: 41-49

[5] Miqdam Tariq Chaichan- “Combustion of Dual Fuel Type Natural Gas/Liquid Diesel

Fuel in Compression Ignition Engine” (2014), PP 48-58

[6] Edwin Geo Varuvel, Nadia Mrad, Mohand Tazerout, Fethi Aloui “Experimental analysis

of biofuel as an alternative fuel for diesel engines “Applied Energy 94 (2012) 224–231

[7] Debabrata Barik, S. Murugan “Investigation on combustion performance and emission

characteristics of a DI (direct injection) diesel engine fuelled with biogas diesel in dual

fuel mode” Energy 72 (2014) 760e771

a review on study of single fuel combustion system and duel fuel combustion system

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