What is defined as excess air?

Excess air refers to the quantity of air supplied for combustion that is greater than the amount theoretically required for complete combustion of the fuel. When combustion occurs, a specific ratio of fuel to air is needed for ideal burning. If additional air is introduced, it is termed excess air. This excess can help ensure that all fuel burns, but too much can lead to inefficiencies, such as wasted heat energy and potentially increased emissions.

Understanding this concept is crucial in stationary engineering, as it influences combustion efficiency, emissions control, and energy consumption in various systems. In contrast, the theoretical air needed for combustion is a fixed amount defined by stoichiometry, while air that improves combustion efficiency and air used to cool down the combustion process pertain to different aspects of combustion technology that do not specifically address the surplus air provided.