Doctoral Dissertations
Date of Award
12-1972
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Chemical Engineering
Abstract
The accurate prediction of the thermal performance of large multitube steam condensers for application to the distillation desalination of seawater depends on the availability of correlations for calculating each of the film heat transfer coefficients for individual tubes located within the condenser as a function of local conditions. Although correlations are available, there have been few experimental verifications of their accuracy or even of their validity in the specific application to desalination, particularly with respect to the two film coefficients associated with the condensation process, the condensate film heat transfer coefficient and the non-condensable gas film heat transfer coefficient.
A horizontal multitube steam condenser was built and operated in the present work in order to investigate the individual and combined effects of steam temperature, steam velocity, condensate rain, and non-condensable gas fraction on the thermal performance of a vertical array of five tubes located within the condenser over the range of interest of each of the variables of importance to the distillation desalination process.
The results were analyzed by comparison with existing and improved correlations. The effect of condensate rain on the condensate film heat transfer coefficient was found to be consistent with previous investigations. A new side drainage model described the observed results and provided the basis for improved prediction methods. The effect of steam velocity was found to be similar in the horizontal direction to that observed by previous investigators in the vertical direction. The effect could be accounted for as being due to the lateral transport of the condensate by the steam out of the region of active condenser tubes, and thus unlikely to occur in large tube bundles. The effect of temperature on the condensate film heat transfer coefficient was found to be consistent with the theoretical prediction of the Nusselt equation.
The combined effect of gas concentration, steam velocity, condensing rate and condensing temperature on the non-condensable gas film heat transfer coefficient was correlated using the Colburn mass transfer j factor and a modified j factor, with the latter being preferred because it led to a considerable decrease in the data scatter about the correlating line. A cavity flow model for describing the process of condensation in the presence of gas in a tube bundle was described and the results analyzed in terms of it.
Design equations for predicting the film coefficients were presented, with values based on the present work incorporated. Recommendations for additional work to generalize the present results are included.
Recommended Citation
Eissenberg, David Martin, "An investigation of the variables affecting steam condensation on the outside of a horizontal tube bundle. " PhD diss., University of Tennessee, 1972.
https://trace.tennessee.edu/utk_graddiss/7874