The liquid temperature in diffusion controlled vapor condensation: analysis and experimental verification

This work deals with the temperature of a liquid film that forms on a thin wire by condensation of vapor present in ambient gas at a small fraction. Based on heat and mass transfer theory in the continuum regime, it is shown that the liquid temperature is steady when the ambient state is steady while a boundary layer in-between may develop in time. An expression for the calculation of the liquid temperature is derived being valid for the geometry of the wire and two other 1-D geometries, namely a plane wall and a sphere. Experiments are carried out with a cylindrical thin wire, the electrical resistance of which was measured in order to obtain the liquid temperature. Results are provided for condensing alcohol and water films showing good agreement with the calculated temperature.