Internal combustion engine fuels (Anti-knocking characteristics and improvement)

May 3 • General • 2294 Views • 1 Comment on Internal combustion engine fuels (Anti-knocking characteristics and improvement)

Internal combustion engine :

This covers the understanding of combustion process in spark ignition engine as well as compression  ignition.It also includes knocking phenomenon and fuel characteristics.It is an engine in which is combustion of a fuel  that is normally of fossils fuel occurs with an oxidizer usually air  in a chamber of combustion  that is an integral part of the working fluid flow circuit. In an internal combustion engine i.e ICE the expansion of the high temperature  and high pressure gases produced by combustion apply direct force  to some component of the engine.It’s  advantages are  It has no valves or camshaft mechanism, hence simplifying its mechanism and construction.For one complete revolution of the crankshaft, the engine executes one cycle—the 4-stroke executes one cycle per two crankshafts revolutions.Less weight and easier to manufacture.Air –fuel ratio is defined as the ratio of air to fuel mixed by the carburetor of fuel injectors.The term air fuel ratio is often called the stochiometric ratio.
Spark Knock

A knock which is recurrent and repeatable in terms of audibility.It is controllable by the spark advance;advancing the spark increases the knock intensity and retarding the spark reduces the intensity.
Knock is the name given to the noise which is transmitted through the engine structure when essentially spontaneous ignition of a portion of the end gas-the fuel,air,residuae gas,mixture ahead of the propagating flame-occurs.
There is an extremely rapid release of most chemical energy in the end-gas,causing very high local pressure and the propagation of pressure waves of substantial amplitude across the combustion chamber.
High power-to-weight ratio.It’s disadvantages are the lack of lubrication system that protects the engine parts from wear. Accordingly, the 2-stroke engines have a shorter life. 2-stroke engines do not consume fuel efficiently. 2-stroke engines produce lots of pollution.Sometimes part of the fuel leaks to the exhaust with the exhaust gases. In conclusion, based on the above advantages and disadvantages, two-stroke engines are supposed to operate in vehicles where the weight of the engine must be small, and it is not used continuously for long periods.The force is applied typically to turbine blades,piston  or a nossle  This force moves the component over a distance, transforming chemical energy into useful mechanical energy. The first commercially successful internal combustion engine was created .Combustion is one process in which air and fuel are burned after being mixed at a correct ratio of 14. 7 parts of air to 1 part of fuel.The specific requirements for combustion including such as air, fuel and ignition requirements,timing,air fuel ratios, compression ratio and engine efficiency.

Surface ignition is ignition of the fuel air charge by any hot surface other than the spark discharge  prior to the arrival of the flame front.It may occur before the spark ignites the charge(pre-ignition) or after normal ignition(post ignition).Surface ignition is ignition of the fuel-air mixture by a hot spot on the combustion chamber walls such as an over heated valve or spark plug, or glowing combustion chamber deposit:

 Question answer

Q1: What is knock?

Ans: Knock is the name given to the noise which is transmitted through the engine structure when essentially spontaneous ignition of a portion of the end gas-the fuel,air,residuae gas,mixture ahead of the propagating flame-occurs.

Q2: It is high power or low power weight ratio?

Ans: High

Q3: What are the specific requirements?

Ans: The specific requirements for combustion including such as air, fuel and ignition requirements,timing,air fuel ratios, compression ratio and engine efficiency.

Q4: Here pressure is high or low?

Ans: High.

Q5: What about temperature?

Ans: High temperature is needed here.

Ic engine characteristicsIgnition of ICEInternal combustion engineSurface ignition

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