Instability in pool boiling of a wide boiling mixture on a horizontal tube

Events occurring during pool boiling of the wide boiling range equimolar pentane/tetradecene mixture on a horizontal tube are described. Due to preferential evaporation of pentane, a film of liquid rich in tetradecene builds up on the lower part of the surface and breaks away from time to time causing fluctuation in the liquid temperature near the boiling surface. The effect of this phenomenon on heat transfer coefficients over a range of heat fluxes is discussed. It is shown that the measured heat transfer coefficients follow the same trend of variation with heat flux as that predicted by Schlunder. However, it is argued that this agreement is fortuitous and that no current prediction method may be used with confidence to estimate heat transfer coefficients of wide boiling range mixtures. © 1991.