In order to study the heat transfer characteristics of pure steam with incomplete condensation in a vertical tube,an experiment was carried out using a heat exchange tube with an inner diameter of 25 mm,with an inlet pressure of 0.1～0.3 MPa and a steam mass flux of 12～70 kg/(m2·s).The effects of inlet pressure,mass flux and mass quality on the average and local condensation heat transfer coefficients in the tube were investigated.The liquid film flow pattern in the condensation process was identified,and the effects of liquid film turbulence and droplet entrainment on the condensation heat transfer in the tube were analyzed.It is shown that the condensation heat transfer coefficient increases with the increase of mass flux and mass quality.However,the condensation heat transfer coefficient of vertical tube decreases with the increase of inlet pressure.The liquid film flow pattern in the experiment is mainly in the transition flow region,and the occurrence of droplet entrainment increases the local condensation heat transfer coefficient.Four annular flow condensation heat transfer equations are compared.The results show that the basic deviation of Shah's empirical equation is within±30％,and the mean absolute deviation(MAD)was 18.91％.An empirical correlation based on the experimental data is developed,and the basic deviation between the calculated value and the experimental value is within±10％.
Vertical tubePure steamIncomplete condensationFilm condensationAnnular flowCondensation heat transfer coefficient
万方数据
维普
