What is defined as excess air?

Excess air is defined as the air that exceeds the theoretical requirement for combustion. In combustion processes, there is a calculated amount of air needed to completely burn a fuel, known as the stoichiometric air requirement. When the actual amount of air supplied during combustion is greater than this stoichiometric amount, the additional air is referred to as excess air.

Introducing excess air is often intentional to ensure complete combustion, which can help to reduce emissions of unburned fuel and improve the overall efficiency of the combustion process. However, too much excess air can also lead to inefficiencies and increased energy consumption, as it can carry away heat that should be used in the process. Thus, understanding the balance of air supply is crucial for efficient combustion.

In contrast, the other definitions outline conditions that do not specifically refer to excess air. The ideal amount of air represents perfect combustion without any excess, air below optimal levels would mean insufficient oxygen for complete combustion, and air remaining after combustion pertains to exhaust rather than excess air.