What occurs during phase separation in alcohol fuels?

During phase separation in alcohol fuels, the process involves the separation of water and alcohol from the fuel mixture. When water is present in alcohol-blended fuels, such as ethanol or methanol blends, it can result in a situation where the ethanol, which is hygroscopic (meaning it absorbs moisture), becomes saturated. When the concentration of water exceeds the solubility limit of alcohol in the fuel, the mixture can no longer stay homogeneous.

As a result, the water and alcohol will separate, causing them to sink to the bottom of the fuel container or tank. This phase separation can lead to operational issues, as the separated mixture can cause problems such as inadequate combustion, fuel line blockages, or engine performance issues. Understanding this behavior is crucial for maintenance and troubleshooting in small engines that use alcohol-blended fuels.