Flow of two liquids in sloping tubes: An analogue of high pressure steam and water

A two-liquid system provides a better analogue for visualization purposes of high pressure boiler systems, where the density ratio is typically 4:1, than air and water at atmospheric pressure. A study is presented of the flow of isoamyl alcohol and water in sloping tubes and a stratified ribbon of alcohol is found, which is not seen with air and water, and this accounts for some corrosion failures in boilers. A critical condition is also encountered when the ribbon starts to be broken into drops and this quantitatively explains the occurrence of a minimum in the curve of burnout heat flux vs water velocity in steam-water systems from 11 to 18 MN/m 2 .