What is a primary cause of aldehyde formation in combustion systems?

The formation of aldehydes in combustion systems is closely associated with low-temperature operations. When combustion occurs at lower temperatures, it can result in incomplete combustion of fuel. This incomplete combustion does not fully oxidize the fuel, leading to the production of intermediate byproducts such as aldehydes. Typically, higher combustion temperatures promote complete fuel conversion into carbon dioxide and water, thereby minimizing the formation of such byproducts.

In contrast, other factors like excess fuel input can lead to incomplete combustion as well, but it's primarily the lower temperature operation that significantly contributes to the increased yield of aldehydes. Similarly, flame impingement may affect the combustion efficiency and can lead to localized high or low temperatures depending on the context, but it is not a direct primary cause of aldehyde formation. Lastly, while reduced oxygen availability may also lead to incomplete combustion, the unmistakable correlation is primarily with low-temperature conditions, where the chemical reactions involved are less efficient in fully oxidizing the fuel.