Inte rnatio nal Jo urnal o f Sc ie ntific & Eng inee ring Re se arc h, Vo lume 3, Issue 3, Marc h 2012 . 1
ISS N 2229-5518
Effect of Injection Pressure on CI Engine Performance Fuelled with Biodiesel and its blends
Sanjay Patil, Dr. M.M.Akarte
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HE depletion, increasing demand and price of the petro- leum prompted extensive research worldwide on alterna- tive energy sources for internal combustion engines. Use
of bio fuels such as vegetable oil could reduce the dependency on petroleum products and the pollution problem. The use of straight vegetable oils (SVO) in diesel engines presents prob- lems primarily due to their high viscosity and lower volatility [1]. SVO can replace diesel oil for short term with l ower out- put [2] but long term and unmodified engine coke up [3]. T a- dashi et.al [4] observed higher carbon deposits and piston rings sticking and R Altin et.al [5] observed higher specific fuel consumption, more carbon monoxide emissions due to higher viscosity. Reduction in viscosity of vegetable oil may improve the engine performance, and can be done by convert- ing it to bio diesel.
N.R. Banapurmath [6] found a slight reduction in thermal efficiency, increase in smoke emissions, increased ignition de- lay and combustion duration with methyl esters of Honge, Jatropha and sesame oil as compared to neat diesel. Lower brake power and torque were observed with bio diesel as compared to diesel [7]. Pradeep and Sharma [8 ] observed that lower Brake thermal efficiencies & heat release rates and high- er combustion duration with biodiesel compared to diesel. Scholl and Sorenson [9] reported that carbon monoxide, oxides of nitrogen (NOX) and smoke emissions were slightly lower for soybean ester than diesel, whereas HC emission showed
50% reduction. Sanjay Patil et.al [10] conducted tests on diesel
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Sanjay patil, Guru Nanak Dev Engineering College, Bidar- India
MMAkarte, National Institute of Industrial Engineering Mumbai-
India. mmakarte@rediffmail.com
oil, neat palm oil methyl ester (POME) and its blends w ith diesel. It was observed that brake ther mal efficiency, brake specific ener gy consumption is impr oved with POME and its blends w ith diesel. The peak pr essur e and rate of pr essur e r ise ar e low er, smoke and hydr ocarbon emissions ar e r educed w ith POME and its blends. Authors [6-10] have evaluated the per- formance of CI engine without changing the injection pres sure. Viscosity of biodiesel is still more than that of diesel at
30°C. Injection of higher viscous fuel results in to larger drop-
lets resulting in poor atomization. By increasing injection pres- sure smaller fuel droplets will be injected may result in better atomization.
Hence an effort is made to investigate the effect o f injec- tion pressure on the CI engine performance fuelled with bi o- diesel and its blends with diesel.
A stationary single cylinder, 4 stroke, water cooled diesel en- gine developing 5.2 KW at 1500 rpm is used for investigation. Technical specifications of the engine are given in Table 1. The engine is coupled to an Eddy current dynamometer. The ma- jor pollutants like smoke and unburned hydrocarbon are measured using smoke meter and four gas analyzer. The fuel flow rate is measured on volumetric basis using burette.
A palm oil methyl ester (POME) is chosen as a potential
alternative biodiesel. Viscosity is measured using redwood
viscometer, flash and fire points are determined using Marten - penesky closed cup apparatus and calorific value is estimated using bomb calorimeter.
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Inte rnatio nal Jo urnal o f Sc ie ntific & Eng inee ring Re se arc h, Vo lume 3, Issue 3, Marc h 2012 . 2
ISSN 2229-5518
TABLE1. SPECIFICATIONS OF ENGINE
Fig.2. Variation of Brake Specif ic Fuel Consumption
An engine is operated on diesel at IP of 200 bar and various blends of POME and diesel as test fuels at IP of 200 bar, 220 bar and 240 bar. The test fuels are namely B20, B40, B60, B80 and B100 prepared with 20%, 40%, 60%, 80% and 100% POME with petroleum diesel respectively. The blends are stirred us- ing magnetic stirrer. Various physical and chemical properties
TABLE.2. PROPERT IES OF DIESEL AND POME
of the test fuels are determined and tabulated in table No 2.
Cylinder pressure data is recorded by using piezoelectric transducer for 80 cycles, averaged and processed wi thin the framework of first law of thermodynamics [11] to compute net heat release.
Fig.3. Variation of Exhaust Gas Temperature
From above figures (1-3) it is observed that the brake thermal efficiency with B60 at injection pressure 220 bar is increased due to better atomization. At injection pressure 240 bar brake thermal efficiency is lowered due to lower momentum of very fine droplets which reduces the droplet penetration in com- bustion chamber. As the injection pressure increases bsfc de- creases due of complete combustion of fuel. Increase in injec- tion pressure assists in better mixing of fuel with air. The ex- haust gas temperature is decreased with increase in injection pressure as a result of better combustion .
Fig.4. Variation of net heat released
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Fig.1. Variation of Brake Thermal Eff iciency
Inte rnatio nal Jo urnal o f Sc ie ntific & Eng inee ring Re se arc h, Vo lume 3, Issue 3, Marc h 2012 . 3
ISSN 2229-5518
Fig.5 Variation of peak cylinder pressure
Fig.8. Variation of carbon monoxide
Above figures (4-5) indicates that at IP of 220 bar B60 shows increased heat release during premixed combustion due to improved atomization and mixing of fuel with air resulting in increased rate of combustion. The peak pressure for B60 is
64.21 bar, 65.29 bar and 64.25bar at IP of 200 bar, 220 bar and
240 bar. Whereas the peak pressure for B0 at IP 200 bar is
65.31bar. This indicates that peak pressure with B60 varies marginally with change in injection pressure and it is compa- rable with diesel.
Fig.9. Variation of oxides of nitrogen
Fig.6. Variation of hydrocarbon emissions
Fig.7. Variation of smoke
Figures (6-9) shows effect of injection pressures on emission of various emitants. Unburnt hydrocarbon, carbon monoxide and smoke emissions are lower at IP of 220 bar for B60 as compared to diesel at 200 bar. The reason may be higher ox y- gen content and better atomization of fuel. The Nox are high- est with B60 at IP of 220 bar due to higher mean gas tempera- ture.
In this study POME is selected as potential biodiesel and vari- ous blends of POME and diesel have been prepared. Engine is operated with each blend at different injection pressure and the performance parameters were computed and the following conclusions are drawn
Engine performance is improved with B60 at IP of 220bar
due to improved atomization of fuel. Brake specific fuel con-
sumption is decreased with increase in load for all the test fu- els. For test fuel B60 at IP of 220 bar the bsfc is lowest. Emi s- sions are lower with biodiesel blends at 220 bar but Nox emis- sions are more. At 240 bar emissions are increased.
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[3] Vellguth G. Performance of vegetable oil and theirmonoesters as fuels fordiesel
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Inte rnatio nal Jo urnal o f Sc ie ntific & Eng inee ring Re se arc h, Vo lume 3, Issue 3, Marc h 2012 . 4
ISSN 2229-5518
engines. SAE 831358, 1983.
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