Published on Apr 02, 2024
Ethanol , an alcohol seems to be a most promising option for countries like India because of its availability from agriculture products. Alcohol can be used in diesel engines in following ways. One method is injection of ethanol with inlet air using carburetion or electronic injection system and other is emulsion of diesel and ethanol . And also enable a reduction in exhaust NO X , smoke and particulate matter .
• viscosity of ethanol is less.
• Specific gravity of ethanol is 0.794.
• Boiling temperature of ethanol is 78C.
• Ethanol has a low cetane rating.
• It is inflammable and its vapour form explosive mixtures with air.
• It is an excellent solvent for fuels, oils, fats etc.,
• It is miscible with water in all proportionate mixing being attended by a concentration of volume.
The easiest method by which ethanol could be used is in the form of diesel ethanol blend . But ethanol has limited solubility in diesel; hence ethanol/diesel solutions are restricted to small percentages (typically 20%). This problem of limited solubility has been overcome by emulsions, which have the capability of accommodation larger displacement of diesel up to 40% by volume. But the major drawbacks of emulsions are the cost of emulsifiers and poor low temperatures physical properties.
Dual injection is a method by which nearly 90%
Displacement of diesel by ethanol is possible. The drawback of this method includes the complexity and expense of a second injection system and a second fuel tank and system.
Spark ignition of neat ethanol in diesel engines provides a way of displacing 100% of diesel. A spark plug and the associated ignition system components must be added to the engine. Space must be available for spark plugs in the cylinder head and its also important for sparkplugs in the cylinder head and it's also important for proper plug cooling
Emulsion is prepared by shaking or stirring by the dispersed phase on dispersed medium or subjecting them to vibration when the emulsifiers are present. Emulsors, stirrers and collide mills and alter sound are used for emulsification. Emulsification consists of dispersion property, the formation of droplets of the dispersed phase face in dispersion medium and their stabilization by absorption in the emulsifier surface. Emulsion stabilized by non-ionogenic emulsifiers is more difficult to destroy.
The experimental setup was carried in a single cylinder air cooled direct injection diesel engine. Table 1 shows the specification of the engine.
Engine type : single cylinder 4 stroke DI engine.
Displacement volume : 779.70CC
Bore : 95mm
Compression ratio : 18:1
Rated speed/power :1500 rpm/5.5kw
The engine is coupled with a BENZ make eddy current dynamometer. An electronically operated control panel was used to vary the load and the fuel flow rate was measured by an electronically operated solenoid switch control fuel flow meter. An AVL smoke meter and 5-gas analyzer were connected to the exhaust manifold to measure the smoke and the exhaust pollutants respectively. The smoke meter works on the light abstraction principle and the level of smoke was given in Hatridge equivalent percentage. The exhaust pollutants carbon monoxide (CO) and unburned hydrocarbon (UBHC) where measured using non-depressive infra-red (NDIR) principle and for the oxides on nitrogen electric chemical absorbent principle were used. A thermocouple was fixed at the exhaust manifold to measure the exhaust gas temperature. A separate fuel tank was fabricated to prepare the emulsion
Though alcohols have been identified as successful contenders for replacing diesel fuel, a large number of innovative concepts need to be used to overcome the problems associated with ethanol in a diesel engine, either neat or its blends with diesel. Modification like hot surface ignition, continuously operated glow plugs, spark plugs, fuel additives, exhaust gas re-circulation, diesel injection, special piston design like sonex combustion system (SCS) [8], intake air heating either by controls on flow from turbocharger or by electric heater are some of the successful methods by which the best performance and also higher percentage of energy replacement are achieved.
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