Boiling on a Substrate. Critical Size of the Bubble

The free energy of formation of a vapor bubble in a conical cavity of a substrate is calculated. An approximate formula is obtained for the characteristic length of the critical bubble. It has been established that the length of such a bubble depends on the angle of wetting and is inversely proportional to the overheating of the liquid. For freon R495, the calculated dependences of the free energy of the critical bubble on the cone apex angle and the wetting angle are given. It is shown that in the case of the same heating in a fairly wide range of these angles, the free energy of bubble formation is much less than in a homogeneous liquid.