Flow of two liquids in a helix: an analogue of high pressure helical boilers

It has been shown previously (Gardner & Kubie 1976) that a two-liquid system provides a better analogue for investigating certain aspects of high pressure boiler tube hydrodynamics than air and water at atmospheric pressure. A study is presented here of the flow of $\text{n-}\text{butyl}$ acetate and water, and iso-amyl alcohol and water in helical coils and the general conclusion is that strongly stratified conditions of either completely separated phases or of drops of one phase in the other exist until velocities are high enough to produce drops sufficiently fine to be dispersed by the turbulence. The critical condition for the breakdown of the separated phases to produce drops is quantitatively correlated with the mass flowrates needed to avoid low quality dryout in both high pressure water and high pressure freon helical boilers. Some evidence is available to support two criteria indicating that low quality dryout will not be observed for sufficiently low pressures in steam-water systems and, perhaps, for small enough bore tubes.