The anti-knock quality of gasoline fuel used in spark ignition internal combustion engine can be enhanced by the addition of lead alkyls .But this results in the formation and emission of toxic lead compounds .a recent practice is to enhance the anti-knock property of the fuel by using certain high octane oxygen containing compounds called oxygenates The use of oxygenates to replace the lead additives in gasoline is considered now as an alternative. The most commonly used oxygenates are MTBE (methyl tertiary butyl ether ), methanol and ethanol .MTBE is manufactured from isobutene and methanol , while methanol is manufactured from natural gas or synthesized from a variety of materials such as coal, municipal wastes and biomass. Ethanol is derived from the direct fermentation of sugars, fermentation of starches and cellulose after chemical or enzymatic pretreatment or made from petroleum sources. These three oxygenates have different chemical and physical properties whencompared to gasoline
These differences are expected to influence the performance and combustion products of gasoline-oxygenates blends. The study offers a comparison between the oxygenated and leaded fuel in terms of engine performance.
Smart combustors
This seminar will review the state of the art of active control of gas turbine combustors processes. The seminar will first discuss recently developed approaches for active control of detrimental combustion instabilities by use of 'fast' injectors that modulate the fuel injection rate at the frequency of the instability and appropriate phase and gain. Next, the paper discusses two additional approaches for damping of combustion instabilities; i.e., active modification of the combustion process characteristics and open loop modulation of the fuel injection rate at frequencies that differ from the instability frequency. The second part of the seminar will discuss active control of lean blowout in combustors that burn fuel in a lean premixed mode of combustion to reduce NOx emissions. This discussion will describe recent developments of optical and acoustic sensing techniques that employ sophisticated data analysis approaches to detect the presence of lean blowout precursors in the measured data. It will be shown that this approach can be used to determine in advance the onset of lean blowout and that the problem can be prevented by active control of the relative amounts of fuel supplied to the main, premixed, combustion region and a premixed pilot flame. The will close with a discussion of research needs, with emphasis on the integration of utilized active control and health monitoring and prognostication systems into a single combustor control system.
Weber carburettors
Weber carburetors were originally produced in Italy by Edoardo Weber as part of a conversion kit for 1920s Fiats. Weber pioneered the use of twin barrel carburetors with two barrels (or venturi) of different sizes, the smaller one for low speed running and the larger one optimised for high speed use.
In the 1930s Weber began producing twin barrel carburetors for motor racing where two barrels of the same size were used. These were arranged so that each cylinder of the engine has its own carburetor barrel. These carburetors found use in Maserati and Alfa Romeo racing cars.
In time, Weber carburetors were fitted to standard production cars and factory racing applications on automotive marques such as Abarth, Alfa Romeo, Aston Martin, BMW, Ferrari, Fiat, Ford, Lamborghini, Lancia, Lotus, Maserati, Porsche, Triumph, and Volkswagen.
In the United States Weber Carburetors are sold for both street and off road use. They are sold in what is referred to as a Weber Conversion kit. A Weber conversion kit is a complete package of Weber Carburetor, intake manifold or manifold adapter, throttle linkage, air filter and all of the necessary hardware needed to install the Weber on a vehicle.
VVT-i
VVT-i, or Variable Valve Timing with intelligence, is an automobile variable valve timing technology developed by Toyota. The Toyota VVT-i system replaces the Toyota VVT offered starting in 1991 on the 4A-GE 20-Valve engine. The VVT system is a 2-stage hydraulically controlled cam phasing system.
VVT-i, introduced in 1996, varies the timing of the intake valves by adjusting the relationship between the camshaft drive (belt, scissor-gear or chain) and intake camshaft. Engine oil pressure is applied to an actuator to adjust the camshaft position. In 1998, 'Dual' VVT-i (adjusts both intake and exhaust camshafts) was first introduced in the RS200 Altezza's 3S-GE engine. Dual VVT-i is also found in Toyota's new generation V6 engine, the 3.5L 2GR-FE V6. This engine can be found in the Avalon, RAV4, and Camry in the US, the Aurion in Australia, and various models in Japan, including the Estima. Other Dual VVT-i engines will be seen in upcoming Toyota models, including a new 4 cylinder Dual VVT-i engine for the new generation 2007/2008 Corolla. Another notable implementation of the Dual VVT-i is the 2GR-FSE D-4S engine of the Lexus GS450h. By adjusting the valve timing, engine start and stop occur virtually unnoticable at minimum compression, and fast heating of the catalytic converter to its light-off temperature is possible, thereby reducing HC emissions considerably