KraftstoffLuftVerhältnis

Kraftstoff-Luft-Verhältnis, abbreviated as AFR in English, is the mass ratio of air to fuel supplied to a combustion system. It describes how much air is available for burning a given amount of fuel and is typically expressed as a ratio of masses (air mass to fuel mass). The concept is central to internal combustion engines and other燃烧 processes, influencing combustion stability, efficiency, and emissions.

For gasoline engines, the stoichiometric AFR is about 14.7:1, meaning 14.7 units of air are required to completely burn one unit of fuel. Other fuels have different stoichiometric values; for example, methane requires around 17.2:1. Real-world operation often occurs on either side of the stoichiometric point: lean mixtures have AFRs greater than the stoichiometric value, while rich mixtures have lower AFRs. The ratio is commonly translated into lambda, where lambda equals the actual AFR divided by the stoichiometric AFR; lambda of 1.0 denotes a stoichiometric mixture.

Engine control systems monitor and adjust the AFR to balance performance, fuel economy, and emissions. Oxygen sensors (lambda sensors) provide feedback to the engine control unit, which uses this information to maintain an appropriate AFR. Gasoline engines often aim near stoichiometric conditions to optimize the performance of three-way catalytic converters; diesel engines typically operate with leaner mixtures to maximize efficiency and reduce fuel consumption, albeit with different emission controls.

In summary, the Kraftstoff-Luft-Verhältnis is a fundamental parameter of combustion design and operation, affecting flame propagation, power output, fuel economy, and pollutant formation. It is controlled dynamically in modern engines to meet performance targets and regulatory standards.