INFLUENCE OF INJECTION
PRESSURE, INJECTION TIMING AND
COMPRESSION RATIO ON
PERFORMANCE, COMBUSTION AND
EMISSION OF DIESEL ENGINE USING
CASTOR METHYL ESTER BLENDS
M. C. Navindgi
Associate Professor, PDA College of Engineering, Gulbarga, 585105, Karnataka, India Email: mcnavindgi@yahoo.com
Dr.Maheswar Dutta
Principal, MNR College of Engineering & Technology, Sangareddy, Medak District, AP, India Email: dr9440212730@yahoo.com
Dr. B. Sudheer Prem Kumar
Principal, JNTUH College of Engineering, Jagtyal, A.P, India Email: bsudheerpk@yahoo.co.in
Abstract:
In the present investigation test were carried out to examine the performance, combustion analysis and emissions of a direct injection diesel engine coupled with eddy current dynamometer fueled with diesel and castor methyl ester and their blends (CME10, CME20 and CME30). From the investigation it is found that the combined increase of compression ratio, injection timing and injection pressure increases the BTHE and reduces BSFC while having lower emissions for CME20. For small sized direct injection constant speed engines used for agricultural applications (5.2 kW), the optimum combination was found as CR of 18:1 with IP of 240 bar and injection timing 27°BTDC. The heat release rates are reduced for Methyl ester of Castor oil blended fuel CME20 compared to diesel. The harmful pollutants such as HC, CO, are reduced in the Castor oil esters compared to diesel fuel.
Key words:, Injection timing, injection pressure, Castor oil methyl esters, performance, emission, combustion
characteristics, Diesel engine
Abbreviations used:
BSFC : Brake specific fuel consumption BTHE : Brake thermal efficiency
BSEC : Brake specific energy consumption HRR : Heat release rate
CHRR : Cumulative heat release rate
1. Introduction
With crude oil reserves estimated to last for few decades, there has been an active search for alternate fuels. The depletion of crude oil would cause a major impact on the transportation sector. Of the various alternate fuels under consideration, biodiesel, derived from vegetable oils, is the most promising alternative fuel to diesel due to the following reasons.
i) Biodiesel can be used in the existing engine without any modifications.
ii) Biodiesel is made entirely from vegetable sources; it does not contain any sulfur, aromatic hydrocarbons, metals or crude oil residues.
iii) Biodiesel is an oxygenated fuel.
iv) Emissions of carbon monoxide and soot tend to reduce.
v) The use of biodiesel can extend the life of diesel engines because it is more lubricating than petroleum diesel fuel.
vi) Biodiesel is produced from renewable vegetable oils/animal fats and hence improves the fuel or energy security and economy independence.
A lot of research work has been carried out to use vegetable oil both in its neat form and modified form. Since India is net importer of vegetable oils, edible oils cannot be used for production of biodiesel. India has the potential to be a leading world producer of biodiesel, as biodiesel can be harvested and sourced from non-edible oils like Jatropha, Curcus, Pongamia Pinnata, Neem, Mahua, Castor, Linseed, etc. Some of these oils produced even now are not being properly utilized. Out of these plants, India is focusing on Jatropha Curcas, Pongamia Pinnata, and Castor which can grow in arid and wastelands.
Implementation of biodiesel in India will lead to many advantages like green cover to wasteland, support to agriculture and rural economy and reduction in dependence on imported crude oil and reduction in air pollution. Castor oil, like currently less expensive vegetable oils, can be used as feedstock in the production of biodiesel. The resulting fuel is superior for cold winters. To the degree that biodiesel replaces diesel refined from fossil petroleum, demand for vegetable oil will increase. Initiatives to grow more castor for energy production, in preference to other oil crops, are motivated by social considerations.
In the present investigation biodiesel is prepared from castor oil .The performance; combustion and emission characteristics were analyzed on a four stroke single cylinder direct injection diesel engine have been used.
Table: Castor oil fatty acids
Average composition of castor seed oil / fatty acid chains
Acid name Average Percentage Range
Ricinoleic acid 95 to 85%
Oleic acid 6 to 2%
Linoleic acid 5 to 1%
Linolenic acid 1 to 0.5%
Stearic acid 1 to 0.5%
Palmitic acid 1 to 0.5%
Dihydroxystearic acid 0.5 to 0.3%
Others 0.5 to 0.2%
2. Biodiesel Production
Esterfication of castor oil comprised heating of oil, addition of sodium hydroxide and alcohol, stirring of the mixture, separation of glycerol, and biodiesel. This esterfied castor oil is called biodiesel. Biodiesel properties are similar to diesel fuel as shown in the Table.1. After esterfication of the castor oil its properties like density, cetane number, viscosity, and calorific value are improved. These parameters induce better combustion characteristics and performance of diesel engine. The biodiesel contain more oxygen and lower calorific value compare than diesel. As a results in lower generation of hydrocarbon and carbon monoxide in the exhaust than diesel fuel.
The physical and chemical properties of Castor biodiesel and its blends are measured as per Indian standards (IS) methods in fuel testing laboratory and tabulated in Table 1. Calorific value and viscosity are measured by Bomb calorimeter and Redwood viscometer (Petroleum Instruments India Pvt. Ltd.), respectively. The flash point and fire point are determined by Pensky-Martens apparatus closed-cup method.
Table.1 Properties of Biodiesel blends compared with neat diesel
Fuel Blend Density (kg/m3)
CV (kJ/kg) Viscosity @40°C (cSt) Flash point (°C) Fire point (°C)
Diesel 850 43000 5.032 78 85
Castor 956 36000 78 320 345
CME10 920 40970 3.3 112 125
CME20 911 40150 3.22 98 109
CME30 898 40046 3.18 81 91
3. Testing Procedure
Figure.1.shows the schematic diagram of the experimental set up and its specification are given in Table.2. Testing was carried out at various loads starting from no load to the full load condition. An Eddy Current dynamometer was used to apply the load on the engine. The compression ratios were changed by changing the cylinder head. At each load, various performance parameters were recorded using Data Acquisition system and various constituents of exhaust gases such as Hydrocarbon (HC), carbon monoxide (CO) were measured with a 4 gas Neptune exhaust gas analyzer. The analyzer uses the principle of non-dispersive infrared (NDIR) for the measurement of CO and HC emissions. Combustion analysis was carried out by means of a Piezo pressure pickup fitted on the cylinder head and a TDC Encoder fixed on the output shaft of the engine. The pressure and the crank angle signals were fed to a Pentium personal computer.
generate the baseline data followed by Methyl Esters Castor and their blends from varying CME10, CME20 and CME30 blends and the test were carried out in the same manner. The results of CME20 blends are comparable with diesel and are presented.
Experimental Setup and Plan
Fig 2.1: Experimental Test Rig.
Nomenclature:
1 Diesel Engine 8 Exhaust gas Calorimeter 2 Eddy current Dynamometer 9 Exhaust temperature indicator 3 Dynamometer Control 10 Air inlet temperature
4 Anti pulsating drum 11 Two way valve 5 Fuel Tank 12 Fuel injection pump 6 Computer with DAQ 13 Crank angle encoder
7 Smoke meter 14 Manometer
Table 2: Engine Specifications
Manufacturer Kirloskar Oil Engines Ltd., India,
Model TV–SR II, naturally aspirated
Engine Single cylinder, DI, Four Stroke
Bore / stroke 87.5mm/110mm
Compression ratio 16.5, 17.5 and 18 (Variable)
Speed 1500 r/min, constant
Rated power 5.2 kW
Injection pressure 240 bar/23° deg BTDC
Type of sensor Piezo electric
Response time 4 micro seconds
Crank angle sensor 1-degree crank angle
Resolution of 1 degree 360 °encoder with a resolution of 10
Table 3: Range of operating parameters tried in the present testing
% Load 0, 25, 50, 75, 100
Speed(rev/min) 1500 Compression ratio 16.5:1,17.5:1,18:1 Injection Timing°BTDC 21,24,27
Injection Pressure(bar) 200, 220, 240
4. Result and Discussion
were set to run at compression ratio 18:1,advanced injection timing 27°BTDC and injector pressure 240 bar to arrive at the optimum for castor methyl esters(CME20). From the experimental analysis it was found that at low injector opening pressure 200 bar and 220 bar and retarded injection timing of 21°BTDC and 24°BTDC and compression ratio 17.5:1 and 16.5:1 were also tried but from the investigation it was found that the performance and emission is very poor.
4.1 Brake Thermal Efficiency
Figure.2. shows the comparison of Brake Thermal Efficiency with Brake Power for different fuels. The maximum brake thermal efficiency obtained is about 31.5% for CME20 and 30.1% for diesel. Increase in thermal efficiency due to high percentage of oxygen presence in the biodiesel, the extra oxygen leads to causes better combustion inside the combustion chamber.
Figure 2: Comparison of Brake Thermal Efficiency with Brake power
The thermal efficiency of the engine is improved by increasing the concentration of the biodiesel in the blends and also the additional lubricity provided by biodiesel. The main reason for increasing the thermal efficiency with increase in injection pressure may be due to atomization.
Figure 3: Comparison of Brake Specific Fuel Consumption with Brake Power
Figure.3.shows the comparison of Brake Specific Fuel Consumption with Brake Power for different biodiesel blends. It can be observed that the BSFC of 0.29kg/kWh was obtained for diesel and 0.28 kg/kWh for CME20.It was observed that BSFC decreased with the increase in injection pressure, the increase in BSFC with the increase in concentration of CME in diesel.
4.3 Brake Specific Energy Consumption
Figure 4: Comparison of Brake Specific Energy Consumption with Brake Power
Figure.4.shows the comparison of Brake Specific Energy Consumption with Brake Power for different biodiesel blends. It was observed BSEC increased with the increase in concentration of CME in diesel and decreases with increasing in injection pressure. The obtained value of BSEC for CME20 of 11500kJ/kWh is
4.4 Unburnt Hydrocarbon
Figure 5: Comparison of Hydrocarbon for different biodiesel blends with respect to brake power
Figure.5.shows the comparison of Hydrocarbon for different biodiesel blends with respect to brake power. It was observed that diesel has the maximum rate of hydrocarbon 36.96 ppm among the tested fuels. It is also found that the hydrocarbon of 30.7 ppm for CME20 decreases with increase in concentration of the biodiesel blends. This may be due to improved combustion because of increased in injection pressure and advanced injection timing.
4.5 Carbon Monoxide
Figure 6: Comparison of carbon monoxide for various biodiesel blends with respect to brake power
4.6 Cylinder Pressure
Figure 7: Comparison of pressure with crank angle for different Castor methyl ester biodiesel blends and diesel at full load
Figure.7.shows the comparison of pressure with crank angle for different Castor methyl ester biodiesel blends and diesel at full load. It was found that the cylinder pressure CME20 (76.87 bar) Diesel (79.375 bar) at 18:1. From the figure it is shown that the pressure increases with increase in injection pressure 240 bar and advanced injection timing 27°BTDC.
4.7 Heat Release Rate
Figure 8: Shows the Comparison of heat release rate with crank angle for different Castor methyl ester biodiesel blends and diesel at full load
4.8 Cumulative Heat Release Rate
Figure 9: Shows the Comparison of cumulative heat release rate with crank angle for different Castor methyl ester biodiesel blends and diesel at full load
Figure.9 shows the Comparison of cumulative heat release rate with crank angle for different Castor methyl ester biodiesel blends and diesel at full load. It is observed that the cumulative heat release rate is increased for CME20 (1391 J) compared to diesel (14454 J). This is due to higher exhaust gas temperature and NOx emission.
Acknowledgements
We thank the management of PDA College of Engineering ,Gulbarga, Karnataka, India for providing us with the necessary experimental set up to perform this research work.
Conclusion
In this investigation the diesel engine have been set to run at compression ratio 18:1, advanced injection timing 27°BTDC and injector pressure 240 bar to arrive at the optimum for Castor methyl esters CME20. At low injector opening pressure 200 bar and 220 bar and retarded injection timing of 21°BTDC and 24°BTDC and higher compression ratio 17.5:1 and 16.5:1 were also tried but from the investigation it was found that the performance and emission is very poor.
It is observed that from the experimental investigation while operating single cylinder diesel engine fuelled with biodiesel from Castor oil esters and their blends, the maximum brake thermal efficiency is found to be CME20 (30.59%) in 27º BTDC and 240 bar at compression ratio 18:1. The results show that at compression ratio18:1, higher injector opening pressure 240 bar and advanced injection timing27ºBTDC and CME20 can gives better performance and emission.
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