Question

Why the temperature increase when flow rate of air increase in air-ch4 combustion, and equivalence ratio always uniforms ??

Answer 1

Solution:

The temperature increase when flow rate of air increase in air-CH4 combustion, and equivalence ratio always uniforms because,

During combustion of CH4 in air the products formed in the reactor releases heat along the central axis of the reactor which results in increase in the temperature of combustion chamber. Due to increase in flow rate of air an oxygen supply become an excess reactant which provides excess oxygen to CH4 for combustion and hence releases more amount o heat. Also if mass flow rate of air and fuel is constant the equivalence ratio will be constant. During excess flow rate of oxygen or air the equivalence ratio will be uniform throughout the reactor or combustion chamber. Excess air leads to complete combustion of fuel.

The flame temperature in the combustor is directly related to the ratio between the air and fuel which is called the air to fuel ratio, it is not only depend on the fuel flow rate. Furthermore, if we want to get the maximum temperature of a flame it should for complete combustion case, and if we want to get the complete combustion you have to premixing the air with the fuel before introduced to the burner by a certain distance to make sure a well premixing hence a well complete combustion.