18-07-2012, 12:47 PM
Effect of Injection Pressure on Performance & Emission for the Blend of Diesel & ‘Karanja’ Biodiesel
a Pressure on Performance & Emission for the Blend of Diesel.pptx (Size: 1.28 MB / Downloads: 64)
INTRODUCTION OF BIODIESEL
The increasing industrialization and modernization of the world has to a steep rise for the demand of petroleum products.
Economic development in developing countries has led to huge increase in the energy demand.
Thus the energy security has become a key issue for the nation as a whole.
Hence it is necessary to look forward for alternative fuels, which can be produced from feed stocks available within the country.
Biodiesel, an eco-friendly and renewable fuel substitute for diesel has been getting the attention of researchers/ scientists of all over the world.
Biodiesel is an alternative fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animal fats.
karanja oil
Karanja, a multipurpose plant, contains high amount of oil in its seeds which can be converted to biodiesel.
Karanja is probably the most highly promoted oilseed crop at present in the world.
The viscosity of Karanja oil is considerably lower than soybean, cottonseed, and sunflower and Cetane no Karanja biodiesel is higher than other biodiesel.
So, pointing to its suitability for use as diesel fuel .
Uses of Karanja
As ornamental plant
As a fence
As a potential oil crop
As raw material for industrial use
Potential as medicinal plant
For enrichment of soil
As potential feed stock
As insecticide/pesticide
As non conventional energy crop
As profitable agro forestry crop
As raw material for dye
Problems with Vegetable Oil using as Fuel in Engine
Diesel fuel has a chain of 12-13 carbons and fresh vegetable oil has a chain length of around 18. To burn in an engine, the chain needs to be broken to be similar in length to diesel.
The high viscosity and poly saturated nature of different types of oil.
Incomplete combustion, characterized by nozzle choking, engine deposits, lubricating oil dilution, ring sticking, scuffing of the engine cylinder liners, injection nozzle failure and lubricant failure due to polymerization of the vegetable oil.
Brake thermal efficiency is lower, brake specific fuel consumption are higher compared to diesel.
Exhaust emissions such as smoke, CO, and Un-burnt hydrocarbons emissions are higher compared to those of diesel.
When the engine is operated for extended periods with vegetable oil, there is a possibility of severe carbon deposit building up and sticking of piston rings. The large droplet size, low volatility, long penetration distances as well as chemical properties of vegetable oils cause such problems.
Remedies with Vegetable Oil using as Fuel in Engine
Heating of fuel and blending with diesel fuel reduces carbon deposit build up and sticking of piston rings.
Heating of vegetable oil reduces the problem connected with viscosity and ensures smooth flow of oil.
Blending of vegetable oil with diesel reduces the viscosity to a great extent, which improves the performance compared to neat vegetable oil.
Exhaust emissions of the blends are lower compared to diesel. This runs successfully on blends of 20-25% vegetable oil and 80-85% diesel without damage to any parts.
Effect of Injection Pressure on Diesel Engine
The main objective of this study is to investigate the effect of injection pressures on performance and emissions characteristics of the engine. The injection pressure was changed by adjusting the fuel injector spring tension.
The performance and emission characteristics of diesel engines depends on various factors like fuel quantity injected, fuel injection timing, fuel injection pressure, shape of combustion chamber, position and size of injection nozzle hole, fuel spray pattern, air swirl etc..
The fuel injection pressure in a standard diesel engine is in the range of 200 to 1700 atm depending on the engine size and type of combustion system employed. [1] The fuel penetration distance become longer and the mixture formation of the fuel and air was improved when the combustion duration became shorter as the injection pressure became higher.
When fuel injection pressure is low, fuel particle diameters will enlarge and ignition delay period during the combustion will increase. This situation leads to inefficient combustion in the engine and causes the increase in NOx, CO emissions.
When the injection pressure is increased fuel particle diameters will become small. The mixing of fuel and air becomes better during ignition delay period which causes low smoke level and CO emission. But, if the injection pressure is too high ignition delay become shorter. So, possibilities of homogeneous mixing decrease and combustion efficiency falls down. Therefore, smoke is formed at exhaust of engine. [1]
Conclusion
The performance, emissions and combustion parameters of 20% honge oil and 80% diesel fuel (volume basis) were found very close to neat diesel fuel where as higher blend ratios were found inferior compared to neat diesel fuel. Improved premixed heat release rate were noticed with H30 when the IOP is enhanced.
Performance and emissions with H30 are even better than neat diesel fuel at enhanced IOP. With increased injection pressure amount of honge oil in blend can be increased from 20% to 30%.