Which of the following is essential for the complete combustion of fuel?

The complete combustion of fuel primarily relies on an adequate supply of combustion air. For combustion to occur efficiently, there must be a sufficient amount of oxygen available to react with the fuel. When the fuel is burned, it combines with oxygen from the air to produce carbon dioxide and water, releasing energy in the process. Without enough combustion air, incomplete combustion can occur, leading to the production of carbon monoxide and other harmful byproducts, as well as reduced energy efficiency.

The other options do not directly impact the combustion process in the same critical manner as combustion air. While conditions such as excessive pressure may influence the combustion environment, they are not essential for combustion itself. Similarly, condensation removal and electric ignition are important in maintaining equipment and ensuring reliable operation, respectively, but neither is as fundamental to the combustion process as the presence of sufficient oxygen. Only with an adequate supply of combustion air can complete combustion be achieved, resulting in optimal efficiency and reduced emissions.