Combustion (1)_Heat Generation

Combustion (1)_Heat Generation

 

Just like human being the engine need to eat air and fuel to generate rotating power. In case of human being we call the power generation process as “digestion” but in the internal combustion engine case we have named it as “combustion”. Combustion is a kind of chemical reaction/ process which convert or change the structure of a certain material into other format and generates heat. In case of gasoline or diesel engine the material flowing into engine is fuel and air and these two material meet inside engine and change themselves into exhaust gas and heat. Now let’s have a look what exactly happens inside engine with a little bit academic glasses.

 

 

The main components of fossil fuel is hydrocarbon (HC) which is a chemical composite of carbon (C ) and hydrogen (H). This hydrocarbon converts into other material if it meets with oxygen under a proper condition of pressure and temperature. This conversion reaction is called as “combustion” which converts HC into H2O, CO2 and heat. If we describe the conversion as a chemical reaction equation, it can be expressed like below.

 

Combustion of Carbon.

C(Carbon) + O2(Oxygen) = CO2(Carbon Dioxide) + 97200 (Kcal)    

Combustion of Hydrogen (High calorific power)

H2(Hydrogen) + 1/2 O2(Oxygen) = H2O(Water) + 68500(Kcal)

  Combustion of Hydrogen (Low calorific power) 

  H2(Hydrogen) + 1/2 O2(Oxygen) = H2O(Water Vapor) + 57750 (Kcal)

 

The term of “High” or “Low” calorific power means that the part of heat energy generated by combustion of hydrogen is used for vaporizing of water or not. The reason of bit lower figure of low calorific power is that part of heat was used already for water vaporization. The two materials at the left hand of (=) are things before combustion, and the materials at the right hand is the material generated after combustion and heat energy which supplies moving power to vehicle. It is practically not possible to count every number of molecules which come into combustion chamber, but any the chemical principle of combustion is well kept up to the level of molecule in the cylinder. Therefore, of we need the number of molecule of Hydrogen and Carbon inside fuel, then we can calculate the amount of air which should come into engine to make an optimal combustion with the given fuel.

 

To be continued at Combustion (2)

 

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