The behaviour of boiling fronts was studied experimentally, using pure liqu
ids and their mixtures. The fronts are generated under isobaric conditions
on the outer surface of a heated tube arranged horizontally in a liquid poo
l. The tube surface was covered with different metallic coatings. Depending
on wall superheat, slow or fast propagating fronts were observed. Slow fro
nts, having Velocities up to 1 ms(-1), were established at low superheats.
Their movement depends on liquid superheat, pressure and properties of the
heating surface. Fast propagating fronts form above a particular superheat,
independent of the characteristic of the heating surface. Their propagatio
n velocity ranges up to 15 ms(-1). At the same superheat, boiling fronts ar
e always slower in mixtures than in at least one of their components. Also,
the minimum superheat required for generating fast fronts in mixtures is s
hifted towards higher values. Both effects are mainly associated with mass
transfer during phase transition.