Experimental Investigation on Performance
Analysis of C.I. Engine using Diesel with Biogas
Rachit Roshan1, Saurabh
Kumar2
1Master of Engineering,
Department of Mechanical Engineering, Raipur Institute of Technology,
Raipur-492101 India
2Associate
Professor, Department of Mechanical
Engineering, Raipur Institute of Technology, Raipur-492101 India
*Corresponding
Author Email: rachitcracker2@gmail.com;
sourabhkumar2002@gmail.com
ABSTRACT:
The conventional fuels are depleting
rapidly because of increase in the living standards and use of advance
technologies. Some major petroleum fuels of this class, especially petrol and
diesel for internal combustion engines are getting exhausted at a frightening
rate. In order to conserve those fuels for survival of technologies, it is
essential to plan for new energy systems. Similarly, the fossil fuels are also
caused environmental problems as they release toxic gases into the atmosphere
at a very high concentration. The energy security and climate change are the
key issues for transformation of energy system from conventional to the
renewable sources. Biogas is a bio-fuel which has high energy value, better
mixing ability and clean burning nature, could be considered as good alternate
to substitute the petroleum fuels.
This paper focuses on thorough analysis and
performance characteristics of a single cylinder, 4-stroke compressed ignition (C.I.)
engine containing dual fuel mode. The biogas used for current work is
considered as a primary fuel whereas diesel is acted as secondary fuel which is
regarded as a pilot fuel. Alone the
diesel contains a large numbers of harmful exhausts, the dual fuel mode
containing biogas-diesel can be an alternative option to get better and clean
burning exhausts. In the current work, the purified biogas (bio-methane, 98%
pure methane) stored at a high pressure cylinder is used in various flow rates.
The performance characteristics such as Brake Specific Fuel Consumption, Brake
Thermal Efficiency and Exhaust Gas Temperature are evaluated properly.
KEYWORDS: Biogas, Diesel engine,
Dual fuel mode.
INTRODUCTION:
Energy is one of the basic
requirements like air and water for survival of the life, the human has
regularly been drawing their energy requirements from the earth and its
surroundings ever since the evolution of the civilization. The fossil fuels,
which were treated as an abundant source to meet energy requirement have been
found to be depleting at an alarming rate. In the current scenario, the search
for alternate source of energy has extensively been carried out since last two
decades. Fuels of bio-origin have been identified as a possible alternative
source, and are more relevant in the developing countries because of their needs
of faster growth and economic stability. Some of the important fuels in this
category are alcohol, vegetable oils, biomass, and bio-diesel. Biogas has been
found to be useful and considered for both developing, and developed countries
as an important substitute of petroleum fuels. Due to tremendous utility of
biogas in Europe, the production is exceeded beyond 7.5 million tons in the
year of 2008. Germany on the other hands
is a leading country which having total 4500 biogas plants and 1650 MW installed
electric power in the year of 2009 and even now
expanding their capacity.
A lot of research work on bio
fuels has been done to save our planet from being polluted. Presently, use of
biogas and its application has been a very hot topic among the researchers as
the exhaust from bio fuels are not so dangerous for environment as compared to
gasoline and diesel and may also be cheaper if produced in bulk. Among bio
fuels, biogas is the gas obtained very easily from waste products; numbers of
research papers has reported on application of biogas for running C.I. and S.I.
engines. [1] Saawomir Wierzbicki
investigated the main constituents, physical and chemical characteristics of
biogas which also highlights the problems associated with engines performance .
They have suggested about the improving of fuel ignitability, burning velocity,
back burning effects, high temperature exhausts and heat transfer mechanism,
during the diesel injection in the IC engines. Baraik
and Murugan [2], have firstly reported to use of
biogas for I.C. engines. They realized that the enormous growth of industries
could be achieved by exploitation of biogas instead of conventional fossil
fuels. Sorathia et al. have performed some experiments
and demonstrated constant speed, single cylinder, vertical air cooled, biogas
premixed diesel dual fuelled C.I. engine which are largely used in agricultural
and water pumping application in rural areas [3]. Stefan Mihic
has worked for problems and their solution during use of biogas for
powering internal combustion engines. Modification of internal combustion
engines for stationary electrical generators and for tractors and light duty
trucks has also been demonstrated [4].
The main objective of the
current work is to analyze the mixing ability, performance characteristics of a
single cylinder, 4-stroke compression ignition (C.I.) engine containing dual
fuel mode. Ultimate aim is to increase the efficiency of engine running on the
duel fuel mode, and optimization of engine performance.
EXPERIMENTAL METHODOLOGY
EXPERIMENTAL SET UP
A single cylinder, 3.7 kW diesel engine engine has been used in the experiment. Set up of the
engine has been shown in the Figure.1. The technical specifications of engine
system are presented in the Table 1. The engine having a water cooling
provision is in-built in the system. The modification has also been made in the
existing system to connect intake manifold with compressed biogas pipe line
like a Y-junction to operate it on a dual fuel mode. For a certain period of
time, the engine operation was idle i.e. on no load condition. The engine was
loaded with a mechanical loading arrangement for obtaining results on different
loading conditions. The readings were noted down, after running the engine at
idling condition for certain period of time and then readings were taken for
different load conditions.
Figure 1.
Experimental setup of engine system
The
performance test was carried out with same test set up and then the engine was
run in a dual fuel mode diesel and biogas both.
Table 1. Engine
specification
|
B.P. |
3.7 kW |
|
Number of Cylinder |
1 |
|
Bore |
85 |
|
Stroke |
110 |
|
Rated Speed |
1500 rpm |
|
Type of cooling |
water |
|
Combustion |
Compressed Ignition |
Biogas used in the
experiment was supplied from biogas plant in a compressed and purified form
(98% methane content) in high pressurized cylinders having a pressure of more
than 50 kg/cm2 . The gas was purified in the biogas plant before
filling into the cylinder.
EXPERIMENTAL PROCEDURE
The
experiment have been preformed with the conventional diesel fuel and kept in
running condition till the temperature reached the operating temperature. The r.p.m. of the engine
has been kept constant for the various loads throughout the experiment.
For diesel and biogas consumption by the engine, all parameters were observed
at different loads of the engine. Moreover, amount of diesel consumption was
also noted for different loads at different flow rates of biogas to calculate
the brake specific fuel consumption. To reduce error in the data each reading
was repeated twice. The brake power, diesel consumption, brake specific fuel
consumption, brake thermal efficiency and exhaust gas temperature on different
loads at varying biogas flow rates were calculated.
Figure 2. Schematic
diagram of experimental setup
To evaluate
comparatively the performance characteristics of C.I. engine using diesel and
biogas in dual fuel mode, keeping engine speed constant readings were noted on
different loads at varying flow rates of biogas.
RESULTS AND
DISCUSSION:
MASS FLOW RATE OF DIESEL (MD)
From Figure 3, it is very
clear that when the flow rate of biogas increases the flow rate of diesel found
to decrease. Since the purified biogas (98% Methane) has been used in the
experiment whose calorific value is 39,820 kJ/kg which was supplied to the combustion chamber having
high purity as compared to non-purified biogas. The calorific value of biogas
adds to the calorific value of diesel (44,800 kJ/kg), and makes total 84,620 kJ/kg
energy value as estimated and supplied to the combustion chamber.
Figure 3. Variation of MD
with B.P. for varying flow rates of biogas
From Figure 3, when the
engine runs on diesel alone, the consumption of diesel is high as compared to
in dual fuel mode till the flow rate range of 0 – 0.350 kg/hr. When we increase
the flow rate of biogas, the consumption rate of diesel starts to increase
beyond the flow rate of 0.350 kg/hr. This is because of flow rate of biogas
increases above 0.350 kg/hr where it stop the air intake i.e
oxygen needed for combustion and the slow down the engine performance by deficient diesel
supply. In this condition, some biogas remains unburnt
as a residual mass in the expansion stroke and there combustion starts after
expansion which leads to extra blasting also known as ignition delay and
results in abnormal sound of engine.
BRAKE SPECIFIC FUEL
CONSUMPTION
Figure 4. Variation of
B.S.F.C. with B.P. for varying flow rates of biogas
Figure 4 compares the brake specific fuel (diesel) consumption of
diesel alone and various flow rates of biogas in intake manifold at varying
loads i.e. 0.508 kW, 1.017 kW, 1.525 kW and 2.034 kW. The graph indicates the
variation of diesel consumption in kg/kWhr., with
respect to load and different flow rates of biogas in intake air in dual fuel
mode.
The B.S.F.C. is highest when
the load is minimum for diesel alone and dual fuel mode. It can be seen from
figure that B.S.F.C. decreases with load for all the test fuels. However
B.S.F.C. is least in the case of maximum biogas supply with intake air when
compared with other test fuels during the entire range of engine operation. At
levels higher than about 40% of maximum load, the deterioration of energy
conversion efficiency of the engine in dual fuel mode is less than that of
lower load conditions due to the contribution of the large fraction of gaseous
fuel (biogas) in the main combustion chamber which leads to faster rate of
flame travel and combustion than the direct injection diesel mode. It is also
noted that biogas-diesel dual fuel engine operation and dual fuel engine
operation with various flow rates of biogas in intake air with respect to brake
power, graph shows least BSFC during the engine operated with maximum biogas
flow rate of 0.350 kg/hr. in intake air as compared to other test fuels over
the entire range of engine operation. Above the flow rate of 350 kg/hr, the
BSFC increases because of excesive amount of fuel
available into the combustion chamber.
BRAKE THERMAL EFFICIENCY
(B.T.E.)
Figure 5. Variation of
B.T.E. with B.P. for varying flow rates of biogas
The brake thermal efficiency
of the engine is one of the most important parameter for evaluating the
performance of the engine. It indicates the combustion behaviour
of the engine to a greater extent. The variation of brake thermal efficiency
with brake power for varying biogas flow rates is shown in above Figure-. It is
noticed that the BTE of the engine increased with increase in loads and
increase in brake power. It is seen that from the flow rate of 0 kg/hr. to
0.150 kg/hr. of biogas, the brake thermal efficiency increases. But as we
increase the flow rate of biogas more than 0.150 kg/hr. , the brake thermal
efficiency starts decreasing, due to the lower calorific value as compared to
the calorific value supplied till the flow rate of 0.150 kg/hr. of biogas.
Still, till the flow rate of 0.350 kg.hr. BTE of the engine is higher as
compared to the diesel alone. But when the flow rate gets increased above 0.350
kg/hr. the BTE decreases as compared to the diesel alone.
3.4 EXHAUST GAS
TEMPERATURE:
Figure 6. Variation of
E.G.T. with B.P. for varying flow rates of biogas
The Figure 6 compares the
brake power and exhaust gas temperature with varying flow rates of biogas. It
can be seen from graph that the exhaust gas temperature increases with the load
with varying flow rates of biogas in intake air and also increases with
increase in flow rate of biogas in intake air for particular load on engine.
It is due to large ignition
delay in dual fuel mode lead to completion of combustion process during the expansion
stroke and engine used for experiment is air cooled. It may avoided by
supplying cool water in jacket water pipe line so as to cool the engine from
time to time. Economically it will be a cost effective task.
·B.P.= 2*Pi*N*T/60
B.P. = W*N/C
·BSFC = MD /B.P.
·BTE = B.P./(CVB*MB+
CVD*MD)
B.P.- Brake Power
B.S.F.C.- Brake Specific Fuel Consumption
B.T.E.- Brake Thermal Efficiency
MD- Mass flow rate of Diesel
MB- Mass flow rate of Biogas
W - Load
N – Revolutions per minute
CVB- Calorific Value of Biogas
CVD- Calorific Value of Diesel
C - Dynamometer Constant 2950
T - Torque
CONCLUSION:
One of the most interesting utilization of
biogas is as vehicle fuel. The substitution of conventional fossil fuels with
biogas can provide up to 80% less of green-house gases emissions. The success
of biogas as a diesel engine fuel requires a readily build infrastructure
therefore biogas now a days could mostly be used in public transportation and
generators. The performance of the engine could be concluded as follows:
·Biogas from organic wastes can be used as
an alternative partial substitution of diesel fuel which may save 40-50% diesel
at different engine load conditions.
·Brake Specific Fuel Consumption decreases
as the flow rate of biogas is increased from 0 to 0.350 kg/hr. but the
consumption of diesel increases as the flow rate of biogas increases above
0.350 kg/hr. . So it is concluded that at the flow rate of 0.350 kg/hr. the
performance on different loads is better.
·Brake Thermal Efficiency increases as the
flow rate increases till the flow rate of 0.150 kg/hr. , thereafter it starts
decreasing due to low energy content of biogas.
·Exhaust Gas Temperature (EGT) increases in
case of biogas –diesel fuelled engine at different loads as compared to diesel
engine.
·The combustion velocity of biogas is little
slow as compared to diesel because of which combustion period is long thereby
decreasing efficiency and reliability. Therefore it is required to purify the
biogas properly before using it for combustion in diesel engine.
·A problem of high exhaust temperature due
to excessive burning of biogas persists.
·Due to micro blastings
also known as knocking, the sound of the engine becomes abnormal.
·By designing suitable combustion chamber
and high compression ratio, performance of the engine could be improved.
·The exhaust emissions from biogas fuelled
vehicles are relatively low in particulates and Nitrogen Dioxide, hence
contribute to improve local air and climate quality.
·As a renewable fuel, biogas helps to reduce
dependence on conventional fossil fuels
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Received on 10.06.2016 Accepted on 22.06.2016 © EnggResearch.net All Right Reserved Int. J. Tech.
2016; 6(1): 04-10 DOI: 10.5958/2231-3915.2016.00002.X |
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