EFFECT OF FRICTION STRESS OF DROPLETS WITH FILM ON PREDICTION OF PRESSURE CHANGES IN CONDENSING TUBES

Abstract

The pressure changes of condensing annular flow in vertical tubes have been predicted using three-fluid model. Use of the previous correlations for the steam-liquid film interfacial friction shows discrepancies between calculated and measured (experimental) pressure changes. Although the correlation of Stevanovic et al. provides good agreement, it has some deficiencies. One of these deficiencies corrected in this paper is introduction of the friction stress between entrained droplets (dispersed phase) and liquid film. Calculated pressure changes provide even much better agreement with measured data by taking the above correction into account such that the agreement of the predictions of the modified three-fluid model with experimental data is 30% better than the agreement of the predictions of Stevanovic et al. correlation with experimental data. The influence of frictional, gravitational and acceleration pressure changes on total pressure change has been analyzed. The entrainment and deposition of droplets has also been considered.

http://dx.doi.org/10.5755/j01.mech.17.1.203