سال انتشار: ۱۳۹۰

محل انتشار: نوزدهمین همایش سالانه مهندسی مکانیک

تعداد صفحات: ۴

نویسنده(ها):

Hamid Saffari – Assistant professor, School of Mechanical Engineering, Iran University of Science and Technology (IUST), Tehran
Nemat Dalir – M.Sc. student, School of Mechanical Engineering, Iran University of Science and Technology (IUST), Tehran, Iran;

چکیده:

The pressure drops of condensing steam downward annular flow in vertical tubes have been predicted using three-fluid model. The use of the previous correlations for the steam-liquid film interfacial friction factor shows discrepancies between calculated and measured pressure drops. Although the proposed correlation by Stevanovic et al. provides good agreement with measured data, it has some deficiencies. Two of the deficiencies corrected in a previous paper by the authors [H. Saffari, N. Dalir, A new modified three-fluid model prediction of pressure changes in condensing vertical tubes] are the use of friction stress of droplets with film and introduction of virtual mass force. The calculated pressure drops provided much better agreement with measured data by taking the above two corrections into account. However, the pressure changes were calculated in a specific steam inlet pressure (i.e. 1.08 MPa). In this paper, the influence of change of inlet pressure (in a fixed value of total mass flux) on pressure drops in downward condensing steam flow in vertical tubes has been investigated and compared with measured data.