Studies on Induced Turbulence Combustion on Performance and Combustion Characteristics of Bio-diesel Fuelled C.I. Engine

monkeyresultMechanics

Feb 22, 2014 (3 years and 5 months ago)

56 views

International Conference on Mechanical and Industrial Engineering
107

Studies on Induced Turbulence Combustion
on Performance and Combustion Characteristics
of Bio-diesel Fuelled C.I. Engine
1
Veeresh M Kodekal,
2
SudeepKumar K S,
3
C R Rajashekar
1-2
Dept. of Mechanucal Engg. Sri Siddhartha Institute of Technology, Tumkur – 572105, Karnataka, India;

3
Professor, Dept. of Mechanucal Engg. Sri Siddhartha Institute of Technology, Tumkur – 572105, Karnataka, India.
1
veershmkodekal@yahoo.co.in;
2
sudeepkumarks@gmail.com;
3
crrtmk@gmail.com
Abstract—This paper presents the effects of modification of piston in C I engine, for inducing turbulence to improve the
combustibility of combustible mixture. A rotating blade has been provided in the crown of the reciprocating piston in the
main combustion chamber. The oscillation of the connecting rod causes the blade to rotate by an angle of 60
o
. This
arrangement induces the turbulence in combustible mixture during combustion, through which better combustion can be
achieved. The effects of induced turbulence, torque and bio-diesel mixture proportion on performance and combustion
characteristics of bio-diesel fuelled CI engine are studied.
Keywords: Induced turbulence, rotating blade piston, Combustibility of combustible mixture
1. INTRODUCTION
The depletion of world petroleum reserves and the
increased environmental concerns have stimulated the
search for alternative sources for petroleum-based
fuel, including diesel fuels. Because of the closer
properties, biodiesel fuel (fatty acid methyl ester) from
vegetable oil is considered as the best candidate for
diesel fuel substitute in diesel engines. The biodiesel
from jatropha oil has similar or better fuel
consumption, horsepower, and torque as conventional
diesel due to low viscosity of biodiesel and high
cetane index. In general, engine performance
characteristics of the biodiesel from jatropha oil were
very similar to those of petrodiesel.
[1,2]
Also the use
of biodiesel in diesel engine results in substantial
reductions of unburned hydrocarbons, carbon
monoxide, and particulate matter.
[3]

Pongamia Pinnata, Jatropha and Neem based
methyl esters (biodiesel) can be directly used in diesel
engines without any engine modifications. Brake
thermal efficiency of B10, B20 and B40 blends are
better than B100 but still inferior to diesel.
[4]
The in-cylinder air motion in diesel engines is
generally characterized by swirl, squish and turbulence,
which have a major impact on air–fuel mixing and
combustion. Swirl motion of the air is usually generated
due to the design of the intake port. A good intake port
design will generate higher swirl and help to improve
combustion. When there is swirl in the in-cylinder air,
the swirl–squish interaction produces a complex
turbulent flow field at the end of compression. This
interaction is much more intense in re-entrant
combustion chamber geometries
[5].

Studies about influence of the air swirl in the
cylinder upon the performance and emission of a diesel
engine shows that in order to achieve the different swirl
intensities in the cylinder, the engine design parameters
can be changed: the cylinder head, piston crown, and
inlet duct can be modified. According to Somender
Singh’s Groove theory a radical design change to the
face of combustion chambers by forming grooves or
channels or passages through the squish areas on cylinder
head will further enhance in-cylinder turbulence followed
by multi flame front combustion. This provides a faster
and efficient burn, with less loss of heat, through his
ISBN: 978-93-81693-89-6

International Conference on Mechanical and Industrial Engineering
108

Studies on Induced Turbulence Combustion on Performance and Combustion Characteristics

design to improve turbulence in combustion chambers.
In the other study, the piston crown is modified i.e.
alteration of combustion chamber to enhance the
turbulence in the cylinder. This intensification of the
swirl is done by cutting number of grooves on the crown
of the piston. This intensifies the swirl for better mixing
of fuel and air and their effects on the performance and
emission are recorded.
[6]

The present study depicts the effect of induced
turbulence on performance and combustion
characteristics of a bio-diesel (Jatropha) fuelled C.I
engine. This includes modification of piston for inducing
turbulence to improve the combustibility of combustible
mixture. For this rotating blades are provided in the bowl
(main combustion chamber) of reciprocating piston.
During the engine operation piston reciprocates inside
the cylinder and connecting rod oscillates (around 60
o
)
which makes the rotation of the blades by same amount.
Rotation of the blades induces high turbulence of the
charge in the cylinder causing better air fuel mixing,
which leads to better combustion, hence improvement in
the performance of the engine.

Fig. 1.1: Standard engine piston

Fig. 1.2: Modified engine piston

Fig. 1.3: Exploded view of modified engine piston

Fig. 1.4: Top View of piston with rotating blades in the
bowl
2. II EXPERIMENTAL SETUP :
The engine test was conducted on four-stroke single
cylinder direct injection water cooled compression
ignition engine connected to eddy current dynamometer
loading. Schematic diagram of the engine test rig is
shown in Fig. 2.1. The engine was always operated at a
rated speed of 1500 rev/min under different loading
conditions( 15%, 30%, 45%, 60% and 75% . The engine
has a conventional fuel injection system. A piezoelectric
pressure transducer was mounted with cylinder head
surface to measure the in cylinder pressure. It is also
provided with temperature sensors for the measurement
of jacket water, calorimeter water, and calorimeter
exhaust gas inlet and outlet temperatures. An encoder is
fixed for crank angle record. The signals from these
sensors are interfaced with a computer to an engine
indicator to display P-Ө, P-V, mass fraction burnt and
heat release versus crank angle plots. The provision is
also made for the measurement of volumetric fuel flow.
The built in program in the system calculates indicated
power, brake power, thermal efficiency, volumetric

International Conference on Mechanical and Industrial Engineering
109

Studies on Induced Turbulence Combustion on Performance and Combustion Characteristics

efficiency and heat balance. The software package is
fully configurable and averaged P-Ө diagram, P-V plot
and other diagram can be obtained for various operating
conditions.

Fig. 2: Schematic Diagram of the Experimental Set-up
PT Combustion Chamber Pressure Sensor
PTF Fuel Injection Pressure Sensor
FI Fuel Injector
FP Fuel Pump
T1 Jacket Water Inlet Temperature
T2 Jacket Water Outlet Temperature
T3 Calorimeter Water outlet Temperature
T4 Calorimeter Water outlet Temperature
T5 Exhaust Gas Temperature before Calorimeter
T6 Exhaust Gas Temperature after Calorimeter
F1 Liquid fuel flow rate
F2 Air Flow Rate
F3 Jacket water flow
F4 Calorimeter Water flow rate
LC Load Cell
CA Crank angle Encoder
EGC Exhaust Gas Calorimeter
3. RESULTS AND DISCUSSION
A series of engine tests were carried out using diesel and
biodiesel (jatropha) blends J10, J20 and J30 to study the
combustion and performance characteristics of CI
engine. Investigations are carried out on the engine
mainly to study combustion characteristics like cylinder
peak pressure, delay period and heat release rate and also
performance characteristics like brake thermal efficiency
and brake specific fuel consumption at compression ratio
of 17.5:1and fuel injection pressure of 175 bar.
Analysis of the combustion characteristics
The comparison charts for cylinder pressure with respect
to crank angle for modified and base piston with J10,
J20, J30 biodiesel (jatropha) blends and pure diesel are
plotted as shown in figures 3.1, 3.2, 3.3 and 3.4
respectively.

Fig. 3.1 Cylinder Pressure Vs Crank angle for J10

Fig. 3.2 Cylinder Pressure Vs Crank angle for J20

Fig. 3.3 Cylinder Pressure Vs Crank angle for J30
‐100
0
100
200250300350400450500
e
r Pressure (Bar)
Crank Angle (deg)
C.R ‐17.5,    Fuel ‐
Biodiesel, J10
Modified 
Piston
Base 
Piston
0
100
200250300350400450500
n
der Pressure 
(Bar)
Crank Angle (deg)
C.R ‐17.5,    Fuel 
‐ Biodiesel, J20
Modified 
Piston
Base 
Piston
0
100
300350400450500
er Pressure (Bar)
Crank Angle (deg)
C.R ‐17.5,    Fuel ‐
Biodiesel, J30
Modified 
Piston
Base 
Piston

International Conference on Mechanical and Industrial Engineering
110

Studies on Induced Turbulence Combustion on Performance and Combustion Characteristics


Fig. 3.4 Cylinder Pressure Vs Crank angle for Diesel

Fig. 3.4a Comparison of Biodiesel (Jatropha)
blends, Diesel
It is observed from the graph that peak pressures are
57.4 bar at 366
0
crank angle for modified piston and 53.7
bar at 370
0
crank angle for base piston. Here peak
pressure variations are less but peak pressures are shifted
towards TDC due to induced turbulence. When it
observed for different biodiesel blends and diesel, less
delay period is noticed for J20 among all the
comparisons.

Fig. 3.5 Heat release Vs Crank angle for Diesel

Fig. 3.6 Heat release Vs Crank angle for Diesel

Fig. 3.7 Heat release Vs Crank angle for Diesel

Fig. 3.8 Heat release Vs Crank angle for Diesel

Fig. 3.9 Comparison of blends of Biodiesel (jatropha),
Diesel
0
100
200250300350400450500550
e
r Pressure (Bar)
Crank Angle (deg)
C.R ‐17.5,    Fuel ‐
Diesel
Modified 
Piston
Base 
Piston
0
100
200 300 400 500 600
d
er Pressure (Bar)
Crank Angle (deg)
Comparison of 
Biodiesel (Jatropha) …
Biodiesel 
J10
Biodiesel 
J20
‐500
0
500
200250300350400450500
Release (J/deg 
CA)
Crank Angle (deg)
C.R ‐17.5,    Fuel ‐
Biodiesel, J10
Modified 
Piston
Base 
Piston
‐500
0
500
200250300350400450500
at Release 
J
/deg CA)
Crank Angle (deg)
C.R ‐17.5,    Fuel 
‐ Biodiesel, J20
Modified 
Piston
‐500
0
500
300350400450500550
l
ease (J/deg CA) 
Crank Angle (deg)
C.R ‐17.5,    Fuel ‐
Biodiesel, J30
Modified 
Piston
Base 
Piston
‐500
0
500
200250300350400450500550
l
ease (J/Deg CA)
Crank Angle (deg)
C.R ‐17.5,    Fuel ‐
Diesel
Modified 
Piston
Base 
Piston
‐500
0
500
200 400 600
elease (J/deg 
CA
Crank Angle (deg)
Comparison for blends 
of Biodiesel 

Biodiesel 
J10
Biodiesel 
J20
Biodiesel 
J30

International Conference on Mechanical and Industrial Engineering
111

Studies on Induced Turbulence Combustion on Performance and Combustion Characteristics

Fig. 3.5 shows the variation of heat release with
respect to crank angle for biodiesel blend J10. It is
observed from the figure that the start of combustion for
modified piston is early, that is at 364
0
crank angle as
against at 367
0
for base piston. Also heat release per
degree of crank angle is more at the initial stage of
combustion for modified piston as compared to base
piston. It is due to turbulence induced by the rotating
blades provided in the piston bowl. It is observed from
the figures 3.6, 3.7 and 3.8 that, biodiesel blend J20 has
earliest start of combustion, that is at 363
0
crank angle as
against 364
0
, 366
0
and 368
0
for J10, J30 and pure diesel
respectively. Due to the induced turbulence, proper
mixing of combustible mixture takes place that increses
the rate combustion hence the efficiency is also
increased.
Analysis of performance characteristics:
Brake thermal efficiency
The comparison charts for brake thermal efficiency with
respect to brake power for modified and base piston also
for various biodiesel blends are plotted as shown in
figures 3.11 and 3.12.

Fig. 3.11 Brake thermal efficiency Vs Brake Power for
Pure Diesel
From the figure 3.11 it is observed that the brake
thermal efficiency for modified piston is increased
marginally. An increase of 0.56% at the 60% load is
noticed. This is because of increased heat release rate due
to induced turbulence.

Fig. 3.12 Brake Thermal Efficiency Vs Brake Power for
Modified Piston
From the fig. 3.12, it is observed that the brake
thermal efficiency is increased for the biodiesel blends.
J20 gives the better results compared to other biodiesel
blends and pure diesel.
When compared with base piston the modified
piston gave inceased thermal efficiency for J20 blend as
shown in fig.3.13.

Fig. 3.13 Brake thermal efficiency Vs Brake Power for
Biodiesel J20
Brake Specific fuel consumption
From the figure 3.14 it is observed that bsfc is decreased
for modified piston for pure diesel marginally because of
the effect of induced turbulence.
5.00
0.00 5.00
ηb.th
in %
BP  in kW
η
b.th
Vs bp For C.R= 17.5
Fuel : PURE DIESEL
Base Piston
Modified 
Piston
10.00
15.00
20.00
25.00
30.00
35.00
0.00 5.00
ηb.th
in %
BP  in kW
η
b.th
Vs bp For C.R=
17.5 Modified Piston
Diesel
Bio‐diesel  J‐
10
0.00
20.00
40.00
0.00 5.00
ηb.th       %
BP  in  kW
η
b.th
Vs  bp  For  C.R= 17.5     
Fuel :  Bio‐diesel J‐20
Base Piston
Modified 
Piston

International Conference on Mechanical and Industrial Engineering
112

Studies on Induced Turbulence Combustion on Performance and Combustion Characteristics


Fig. 3.14 bsfc Vs BP for Pure Diesel
From the figure 3.15, it is observed that the bsfc is
decreased for the biodiesel blends for modified piston.
J20 blend giving good results because of the effect of
induced turbulence.

Fig. 3.15 bsfc Vs BP for Modified Piston

Fig. 3.16 bsfc Vs BP for Biodiesel J20
Figure 3.16 shows that the biodiesel J20 gives lesser
bsfc for modified piston as compared to base piston for
all the loads.
4. CONCLUSION
Combustion characteristics and engine performance
characteristics for blends of transesterified jatropha oil
and diesel were compared for base piston and modified
piston with induced turbulence. The variation in the peak
pressures is not significant but decrease in the delay
period of about 3 to 4 deg. in crank angle was observed
for modified piston compared to base piston is observed.
Heat release per degree of crank angle is more at initial
stage of combustion for modified piston compared to
base piston with biodiesel blend J20 giving better result.
The specific fuel consumption is slightly lower for
modified piston compared to base piston. Biodiesel blend
J20 giving the better results among all the biodiesel
blends and pure diesel for modified piston. The brake
thermal efficiency for modified piston is increased
compared to base piston for pure diesel. Also biodiesel
J20 giving higher thermal efficiency among all the
biodiesel blends and pure diesel for modified piston. This
is due to the proper mixing of the combustible mixture by
induced turbulence in the modified piston thus increasing
the heat release rate and efficiency, decreasing the brake
specific fuel consumption.
REFERENCES
[1]. Tint Tint Kywe, Mya Mya Oo.,Production of
Biodiesel from Jatropha Oil (Jatropha curcas) in
Pilot Plant, Proceedings of world academy of
science, engineering and technology volume 38
FEBRUARY 2009 ISSN: 2070-3740
[2]. Thangavelu ELANGO , Thamilkolundhu
Senthilkumar , Combustion and emission
characteristics of a diesel engine fuelled with
jatropha and diesel oil blends, Thermal science,
Year 2011, Vol. 15, No. 4, pp. 1205-1214 1205
[3]. F.Halek, A.Kavousi, and M. Banifatemi,
“Biodiesel as an alternative fuel for Diesel
Engines,” World Academy of Science, Engineering
and Technology, 57, 2009
[4]. T. Venkateswara Rao , G. Prabhakar Rao , and K.
Hema Chandra Reddy ‘Experimental
Investigation of Pongamia, Jatropha and Neem
Methyl Esters as Biodiesel on C.I. Engine’ Jordan
Journal of Mechanical and Industrial Engineering
Volume 2, Number 2, Jun. 2008 ISSN 1995-6665
Pages117 – 122
0.200
0.300
0.400
0.500
0.600
0.700
0.00 5.00
bsfc      in   

BP  in kW
bsfc Vs bp For C.R=
17.5 Fuel : DIESEL
Base Piston
Modified 
Piston
0.2500
0.3500
0.4500
0.5500
0.6500
0.7500
0.00 5.00
bsfc      in   

BP  in kW
bsfc Vs bp For C.R=
17.5 Modified
Piston
Diesel
Bio‐diesel  J‐
10
0.250
0.450
0.650
0.50 2.50 4.50
bsfcin   

bp  in kW
bsfc Vs  bp   For  C.R= 17.5    
Fuel :  Bio‐diesel J‐20          
Base Piston
Modified 
Piston

International Conference on Mechanical and Industrial Engineering
113

Studies on Induced Turbulence Combustion on Performance and Combustion Characteristics

[5]. B.V.V.S.U. Prasad, C.S. Sharma, T.N.C. Anand,
R.V. Ravikrishna ‘High swirl-inducing piston
bowls in small diesel engines for emission
reduction’, Elsevier, Applied Energy 88 (2011)
2355–2367
[6]. S.L.V.Prasad, Prof .V.Pandurangadu, V.V.
Pratibha bharathi, V.V.Naga deepthi, Experi-
mental study of the effect of in cylinder air swirl
on diesel engine performance, International
Journal of Engineering Science and Technology
(IJEST), Vol. 3 ,No. 2 ,Feb 2011