Superheating of liquid xenon in metal tubes.
The method of measuring the lifetime has been used to investigate the kinetics of spontaneous boiling-up of superheated xenon in copper tubes. In experiments the temperature dependence of the mean lifetime has been determined at pressures of 1.48 and 1.98 MPa. The data obtained have been compared with homogeneous nucleation theory. It has been found that experimental values of the attainable superheating temperature and the derivative (partial differential ln J/partial differential T)p are systematically lower than their theoretical values. A description of experimental data in the framework of heterogeneous nucleation theory has shown that for the agreement of theory and experiment with the use of a macroscopic model of nucleation on a smooth surface it is necessary to take the value of the equilibrium contact angle theta0 equal to 70 degrees, which is not a characteristic for a xenon-metal system. Taking into account the contribution of the energy of the three-phase contact solid wall-liquid-gas in a microscopic nucleation model makes it possible to reconcile heterogeneous nucleation theory and experimental data at a contact angle theta0 close to zero, with the linear tension taken equal to -6 x 10(-12) J/m and the microscopic contact angle theta* approximately 57 degrees. The number of weakened sites, on which bubbles may form, is always smaller than the number of molecules adjacent to the solid wall.
Baidakov
V G
VG
Institute of Thermal Physics, Ural Branch of the Russian Academy of Sciences, 106 Amundsen Street, Ekaterinburg 620016, Russia. baidakov@itp.uran.ru
Kaverin
A M
AM