Investigation Of Condensation Of Low-Pressure Vapor In A Horizontal Tube

The phenomenon of condensation of low-pressure vapor in a horizontal tube is studied. The interactions between heat flux density, vapor pressure, vapor velocity and the coefficient of heat transfer for condensation in tube, the coefficient of heat transfer in total are investigated. The relationships between heat flux density and the total difference in temperature, the difference of temperature, pressure drop of vapor from the entrance of the tube to the exit are investigated as well. The results indicate that the qualitative behavior in this process is similar to that observed in condensation of vapor at or above atmosphere pressure, the coefficient of heat transfer for condensation in tube, the coefficient of heat transfer in total increase with the increasing of heat flux density and vapor pressure. However, heat flux density and vapor pressure have a more significant effect on them. The theory of interface of two-phase fluid id used to analyze the role of the interfacial heat transfer resistance in condensation process, it shows that the interfacial heat transfer resistance can not be ignored under such a vacuum condition, and the effect on heat transfer process becomes declined with the increasing of vapor pressure. Analytical relationships are obtained for calculation of the coefficient of heat transfer for condensation in tube, the relative difference between the experimental value and the calculated value is smaller than+15%.