hi, i am having a little difficulty of understanding what these turn means and h

Question

hi, i am having a little difficulty of understanding what these turn means and how to solve a problem on combustion chamber.

in a combustion chamber process. how do you know the products of the reaction in these cases and please give an example:

1) excess air

2) when one mole of a substance is burned with air that contains 20kmol of O2.

3) complete combustion

4) stoichiometric air

5) stoichiometric combustion

6) deficiency of air

7) the dew point temperature

8) one mole of a substance is burned with 20% excess air during a combustion.

10) what property tables do you use when calculating enthalpy formation and what is the theory behind it.

Explanation / Answer

Since the fuel is the valuable component during combustion reaction, to ensure complete combustion of fuel, normally 15 to 25% excess air is sent along with the fuel into the combustion chamber.

For example, when 1 mole of CH4 is burnt, the following reaction takes place.

CH4+ 2O2------>CO2+2H2O

Moles of oxygen required= 2 moles / mole of CH4

Since air contains 21% O2 and 79% N2, moles of air to be supplied= 2/0.21=9.52

Air is normally supplied at 25% excess. Moles of air supplied= 9.52*1.25= 11.9 moles

2. From the above example, if 1 mole of substance ( assuming it to be gmole), moles of oxygen supplied =20 kmol. Moles of air supplied= 20/0.21 =95.23 kmoles of Air.

Actually for the above reaction, air is supplied in very much excess rate.

3. for the reaction CH4+ 2O2--->CO2+2H2O, for complete combustion , 2 moles of oxygen is supplied and air supplied= 2/0.21= 9.52moles. Excess air supplied is 25% and hence moles of air supplied= 9.52*1.25= 11.9 moles. This ensures complete combustion of fuel.

4. for the reaction CH4+ 2O2--->CO2+2H2O, for complete combustion , 2 moles of oxygen is supplied and air supplied= 2/0.21= 9.52moles. Since nitrogen is an inert present in air, the heat carried by nitrogen due to it being supplied in stoichiometric amounts, the adiabatic flame temperature calculated based on enthalpy balance will be more than that of adiabatic flame temperature in presence of excess air.

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.