Table of Contents
How does fuel air mix affect combustion?
The effect of air-fuel ratio was more visible on the initial stage of the combustion at lower speeds while it is visible on the rapid burning stage at higher speeds. Moreover, the combustion duration was increased with an increase in engine speed.
What is the purpose of excess air in furnace combustion?
To ensure complete combustion of the fuel used combustion chambers are supplied with excess air. Excess air increase the amount of oxygen to the combustion and the combustion of fuel.
What is significance of excess air?
Excess air ensures that there is enough air for complete combustion. Excess air is expressed as a percentage of theoretical air required. Thus, 10% excess air indicates that 110% total air is being supplied. In boiler operation, excess air represents a heat loss.
What is the reason for increasing the air fuel ratio of a mixture?
The ideal (theoretical) air-fuel ratio, for a complete combustion, is called stoichiometric air-fuel ratio. For a gasoline (petrol) engine, the stoichiometric air-fuel ratio is around 14.7:1. This means that, in order to burn completely 1 kg of fuel, we need 14.7 kg of air….Air-fuel ratio, lambda and engine performance.
| Fuel | Chemical formula | AFR |
|---|---|---|
| Hydrogen | H2 | 34.3:1 |
What happens to the air fuel mixture?
When fuel burns in the presence of oxygen, it is converted to carbon dioxide, water, and heat. Air contains approximately 21% oxygen and 79% nitrogen. In this case, the reaction for complete combustion becomes: CH4 + 2O2 + 7.53N2→ CO2 + 2H2O + 7.53 N2 + Heat (1,013 Btu/ft.3)
What happens to the air fuel mixture intake stroke?
During the intake stroke, the fuel and air mixture is drawn into the cylinder with the exhaust valve closed. Then the air and fuel mixture is compressed in a compression stroke. The gases expand completely, the exhaust valve opens, and the gases are expelled out during the exhaust stroke.
What effect if any would an increase in excess air have on combustion?
Too much excess air leads to lower flame temperature. That means less heat gets into the system. Also, excess air must heat up to flue gas temperature, which consumes extra energy.
What happens to the flame if there is too much primary air?
When burning Hydrocarbon fuel there are two reactions taking place within the flame. The secondary air will control the flame pattern but too much primary air will create a smaller brighter flame that will not give off as much heat causing you to burn more fuel.
What happens if too much air is supplied to the furnace?
What happens if not enough air goes into the burner?
When combustion is deprived of the necessary oxygen, the correct ratio between the air and fuel changes to a fuel-rich, air-lean ratio. This causes an oil flame to become bright, orange, and soot-producing.
What is the importance of fuel air ratio in IC engine?
In an internal combustion engine or industrial furnace, the air-fuel ratio is an important measure for anti-pollution and performance-tuning reasons. If exactly enough air is provided to completely burn all of the fuel, the ratio is known as the stoichiometric mixture, often abbreviated to stoich.
What is the significance of a proportional fuel and air mixture?