Testing of the Gasoline-ethanol Blends in Carburetor Type Spark Ignition Engine

Testing of The Gasoline-Ethanol Blends In Carburetor Type Spark Ignition Engine, Puneet

Singh, Rishi Pareek, Journal Impact Factor (2015): 8.8293 Calculated by GISI (www.jifactor.Com)

www.iaeme.com/ijmet.asp 43 [email protected]

1Asst Prof., Dept. of Mechanical Engineering, WIT,

Uttarakhand Technical University Dehradun, Uttarakhand

2Research Scholar, Dept. of Mechanical Engineering, SVNIT Surat, Gujarat,

ABSTRACT

This paper presents an analysis of carburetor type spark ignition (SI) engine using gasoline-

ethanol blends. The most captivating properties of ethanol as a SI engine fuel are that it can be

produced from renewable energy sources such as agricultural feedstock and has high octane number

(108) and flame speed.

In the present work, tests were conducted on carburetor SI engine under different loads for all

blends of gasoline-ethanol. For each blend readings were taken for varying load. The experiments

conducted using gasoline-ethanol blends with the volumetric ratio ranging from 0% to 50% with an

increment of 5% ethanol. The results showed that blending increases the brake thermal efficiency,

volumetric efficiency and fuel consumption. The CO, HC and NOx emissions concentrations in the

engine exhaust decreases, while the CO2 concentration increases. It can be concluded from the

research work that 20% ethanol in fuel blend with gasoline gave the best result for all measured

parameters at all loads.

Keywords: Biomass, Ethanol, Renewable Energy, SI engine.

1. INTRODUCTION

In present scenario, people around the world use fossil fuels for energy production, the

reserves of these petroleum based fuels are being rapidly depleted. The consumptions of fossil fuels

in internal combustion (IC) engines and the associated environmental impacts are now the world

wide concerns. Alternative fuels as defined by the Energy Policy Act of 1992 (EPACT, US), include

ethanol, natural gas, hydrogen, biodiesel, electricity, methanol and so on. These fuels are being used

worldwide in a variety of vehicle applications.. Ethanol was the first fuel among the alcohols to be

used to power vehicles in the 1990s.

Number of published work available on Carburetor type SI engine using gasoline-ethanol

blends of fuel, many of them are considered as reference for current research work

TESTING OF THE GASOLINE-ETHANOL BLENDS IN

CARBURETOR TYPE SPARK IGNITION ENGINE

Puneet Singh1, Rishi Pareek2

Volume 6, Issue 6, June (2015), pp. 43-51

Article ID: 30120150606005

International Journal of Mechanical Engineering and Technology

© IAEME: http://www.iaeme.com/IJMET.asp

ISSN 0976 – 6340 (Print)

ISSN 0976 – 6359 (Online)

IJMET

© I A E M E




Among the various alcohols, ethanol is known as the most suited fuel for spark-ignition (SI)

engines. The main reason for advocating ethanol is that it can be produced by fermenting and

distilling starch crops that have been converted into simple sugars, feedstock for this fuel include

corn, barley and wheat. Ethanol can be produced from cellulose feedstock such as corn stalks, rice

straw, and sugar cane which are examples of feedstock that contain sugar [1-4]. In [5], the

experimental investigation on single cylinder two stroke spark ignition engine in carburettor and

direct fuel injection modes has been presented. In [6], brake thermal efficiency of LPG fuelled

engine is compared with that of gasoline at different compression ratio and ignition timing. In this

paper, different tests were conducted on carburetor SI engine under different loads for all blends by

varying load.

2. DIFFERENT BLENDS OF ETHANOL WITH GASOLINE

There are different types of gasoline-ethanol blends used all over the world. Gasoline-ethanol

blends including ethanol at low proportions can be used without any engine modifications but pure

ethanol requires major modifications to the engine design and fuel system. Consequently, the use of

gasoline-ethanol blends in SI engines is more practical than using ethanol alone. The properties of

the blended fuels used for experimentation are calculated implementing below equations:

Density of blends

100

j j

bl

X ρρ =

∑ (1)

Stoichiometric fuel/air ratio of blends

( / )( / )

j j sj

sbl

j j

X F AF A

X

ρ

ρ=∑∑

(2)

Lower heating value of blends

j j j

bl

j j

X LHVLHV

X

ρ

ρ=∑∑

(3)

where, subscript j refers to gasoline (G) or ethanol (E) and X is the volume percentage of gasoline or

ethanol.

Density of the gasoline used in the experiments was measured as 769 kg/m3[7] and its

approximate molecular formula was taken as C8H18. Density of ethanol was measured as 795

kg/m3. The purity of ethanol corresponding to this density is calculated as 95% by using the densities

of pure ethanol having purity of 99.99% and water as follows:

w E

w EP

PRTρ ρ

ρ ρ

−=

− (4)

where EPρ is the density of pure ethanol and taken as 785 kg/m3. wρ is the density of water and

taken as 1000 kg/m3.

In the Table 2, theoretical properties of different blends of ethanol with gasoline are shown.

The data in Table 2 has been utilized for further calculations.




TABLE 2: Theoretical properties of different blends of ethanol with gasoline

Blends Density 3

LHV S. A/F

E0 765 44 14.6

E5 766 43.12 14.1

E10 767 42.25 13.7

E15 768 41.38 13.3

E20 769 40.51 13.0

E25 770 39.64 12.7

E30 771 38.78 12.2

E35 772 37.91 11.9

E40 773 37.05 11.6

E45 774 36.20 11.4

E50 775 35.34 11.1

3. EXPERIMENTAL SETUP

In this work, most widely used Carburetor type SI engine of MARUTI 800 was selected for

experiment purpose. The four stroke engine has three cylinders with compression ratio of 8.7, other

specifications are stated below.

• General details – three cylinder, four stroke, spark ignition, water cooled, Carburetor type SI

MARUTI 800 engine

• Bore = 68.5 mm, Stroke = 72 mm

• Piston displacement = 796 cc

• Compression ratio = 8.7:1

• Maximum output = 37 HP @ 5000 RPM

3.1 Performance Examination

The effect of ethanol addition to unleaded gasoline on carburetor type SI engine performance

and exhaust emissions at full throttle opening at constant speed were investigated. For this

investigation main objective was to analyze performance of ethanol blended with gasoline fuelled

engine and find out the best blend for all loads. The engine was started and allowed to warm up for a

period of 10-20 min. Engine test were performed at different blends with the volumetric ratios of 0%

to 50% with an increment of 5% ethanol, operated with each blend at constant speed with varying

load.

The parameters, such as fuel consumption rate, brake specific fuel consumption, volumetric

efficiency, brake thermal efficiency, mechanical efficiency, air-fuel ratio, CO and NOx emissions

were estimated.

3.1.1 Calculations

A load test was done with gasoline and its blends with ethanol as fuel on the Carburetor type

SI engine. This was done to obtain a set of performance parameters calculated as follows:

Brake power

* * 0.736

( )1000

=W N

BP kW (5)

where, W = Spring balance reading in kg, N = speed of the engine in rpm




Mass of fuel consumption

*0.72*3600

( / )1000*

ccX

mfc kg hrT

= (6)

where, X = burette reading in cc

0.72 = density of gasoline in gram/cc, T = time taken in seconds

Specific fuel consumption

( / )mfc

Sfc kg kWhrBP

= (7)

Actual volume of air sucked into the cylinder

3

( / ) * * 2 *3600a d

V m hr C A gh= (8)

where, ( ) *1000

h wH m

a

δ

δ= meter of water

A = area of orifice = π d2/4 in m2

d = 20 mm, h = manometer reading in mm

wδ = density of water = 1000 kg/m3

aδ = density of air = 1.193 kg/m3

dC = co-efficient of discharge = 0.62, g = acceleration due to gravity = 9.81 m

2/s

Swept volume

2

3( / ) * * *60*34 2

s

d NV m hr L

π=

where, d = diameter of the bore = 0.0685 m

L = length of the stroke = 0.072 m, N = speed of the engine in rpm

Volumetric efficiency

(%) *100av

s

V

Vη = (10)

Brake thermal efficiency

*3600

(%) *100*

bth

v

BP

mfc Cη = (11)

where, vC = calorific value of gasoline = 44000 kJ/kg

Mechanical efficiency

(%) *100mech

BP

IPη = (12)

where, IP = indicated power in kW

4. RESULTS AND DISCUSSIONS

The following discussion is based on the results of the load test conducted on the three

cylinder Carburetor SI engine experimental setup. The experiment was conducted on engine speed of

2500 rpm. The results are shown by various graphs in Figs. 1 to 6, giving details about the impact of

load change on mass of fuel consumption, brake specific fuel consumption, brake thermal efficiency,

volumetric efficiency, mechanical efficiency and air-fuel ratio respectively.

4.1 Mass of fuel consumption

The effect of the ethanol-gasoline blends on the fuel consumption is shown in Fig. 1. The fuel

consumption increases as the E% increases for all loads.




Figure. 1 The effect of ethanol addition on the fuel consumption rate.

4.2 Brake specific fuel consumption (SFC)

In Fig. 2, shows the effect of using ethanol-gasoline blends on brake specific fuel

consumption. Owing to fact that the heating value of ethanol is lower than that of gasoline, the SFC

increases as the ethanol content in the blend increases. At no-load the SFC curve is at infinity as the

engine is producing no useful work and is consuming fuel. As the load is increased the curve starts to

drop and achieve a minimum

Figure. 2 The effect of ethanol addition on the specific fuel consumption.

4.3 Brake thermal efficiency

Fig. 3 presents the effect of using ethanol-gasoline blends on brake thermal efficiency. As

shown in the figure, brake thermal efficiency increases as the E% increases. The maximum brake

thermal efficiency is recorded with 20% ethanol in the fuel blend for all loads. The brake thermal

efficiency curve is the inverse of specific fuel consumption curve.




Figure. 3 The effect of ethanol addition on the brake thermal efficiency.

4.4 Volumetric efficiency

Fig. 4 shows an increase in the volumetric efficiency as the percentage of ethanol in the fuel

blends increases. This is due to the decrease of the charge temperature at the end of the induction

process. This decrease is attributed to the increase in the charge temperature as a result of the heat

transfer from the hot engine parts and the residual gases in the charge.

Figure. 4 The effect of ethanol addition on the volumetric efficiency.

4.5 Mechanical efficiency

Figure. 5 The effect of ethanol addition on mechanical efficiency.




Fig. 5 shows increase in the mechanical efficiency as the percentage of ethanol in the fuel

blends increases. The mechanical efficiency increases up to 20% ethanol blend with gasoline. The

ethanol has the better lubricating property compared to gasoline because of this it reduces the friction

losses. The indicated power increases and frictional power almost constant.

4.6 Air-fuel ratio

Fig. 6 shows a decrease in the air-fuel ratio as the percentage of ethanol in the fuel blends

increases. The heating value of ethanol is lower compared to gasoline engine needs more fuel obtain

the same power. The mass of fuel consumption increases with increasing ethanol percentage in

blends with gasoline. So the air-fuel ratio decreases with increasing ethanol percentage in the blends

with gasoline.

Figure. 6 The effect of ethanol addition on the air-fuel ratio.

4.7 Exhaust emissions

Figure. 7 The effect of ethanol addition on CO emission.

In this study only impact on CO and NOx emissions was examined. However, the other

emissions factors can be examined also. Figs. 7 and 8 portray the effect of E% in the fuel blend on

the CO and NOx. From this figures it can be observed that as the E% increases to 20%, the CO and

NOx concentrations decreases and then increases for all loads.




The exhaust emission also improved with using ethanol blends. The CO and NOx emissions

decreased with increasing ethanol percentage in gasoline.

Figure 8. The effect of ethanol addition on NOx emission.

From above discussion, it is concluded that the ethanol blends with gasoline gave the better

result. The 20% ethanol percentage of ethanol gave the better engine performance with compared to

other blends. The mass of fuel consumption, brake thermal efficiency, volumetric efficiency and

mechanical efficiency increases with ethanol blends with gasoline, on the other hand air-fuel ratio

decreases using ethanol blends with gasoline. The exhaust emission also improved with using

ethanol blends. The CO and NOx emissions decreased with increasing ethanol percentage in

gasoline.

5. ACKNOWLEDEGMENT

We are very much thankful to lat. Mr Neeraj Kumar for this valuable suggestions and

guidance to complete our work.

6. CONCLUSIONS

The experimental performance on carburetor SI engine with different ethanol blends with

gasoline was investigated. The main outcomes of this analysis are as:

1. The experiments shows that 20% ethanol blend with gasoline gives the best performance for

the carburetor SI engine.

2. Ethanol blended with gasoline always improves the performance of carburetor SI engine and

reduced the exhaust emissions also.

3. Ethanol addition results in an increase in brake thermal efficiency, volumetric efficiency,

mechanical efficiency and fuel consumption by about 1%, 26%, 9% and 22% respectively at

lower load and about 2%, 7%, 4% and 13% respectively at maximum load at 20% percent

ethanol blend with gasoline.




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Testing of the Gasoline-ethanol Blends in Carburetor Type Spark Ignition Engine