Analytical and numerical study for two-phase stratified-flow in a plane channel subjected to different thermal boundary conditions

2013 ◽  
Vol 71 ◽  
pp. 88-102 ◽  
Author(s):  
Vinesh H. Gada ◽  
Debabrata Datta ◽  
Atul Sharma
Keyword(s):  
Boundary Conditions ◽  
Numerical Study ◽  
Plane Channel ◽  
Stratified Flow ◽  
Two Phase ◽  
Thermal Boundary Conditions

An Experimental Study of Thermal Performance of a Two-Phase Loop Thermosyphon (TPLT)-Based Steam Generator: Effects of Thermal Boundary Conditions

2013 ◽  
Author(s):  
Meng Hua ◽  
Liang Zhang ◽  
Zi-Qin Zhu ◽  
Li-Wu Fan ◽  
Zi-Tao Yu ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Thermal Performance ◽  
Flow Instability ◽  
Natural Circulation ◽  
Filling Ratio ◽  
Two Phase ◽  
Thermal Boundary Conditions ◽  
Heating Section ◽  
Phase Loop ◽  
Ratio Condition

For the Parabolic trough collector (PTC) system, thermal boundary condition of the receiver (or heating section) is important for the thermal optimization. In this work, effects of thermal boundary on thermal performance of the two-phase loop thermosyphon (TPLT) natural circulation PTC system was investigated experimentally. Three kinds of thermal boundary heating conditions (upper and lower half, and whole circular heated) and two filling ratios (FR = 0.6, 1.2) were adopted in this paper. The results show that half heating condition can improve heat transfer performance in receiver and system thermal resistance. But the preferred half heating boundary was varied as the filling ratio was changed. However, a lower thermal efficiency was observed for the partly heating boundary conditions. For a low heat flux condition in this work, the effects of thermal boundary on flow instability were not obvious, especially for the bigger filling ratio condition.

Hyperbolicity Analysis of a One-Dimensional Two-Fluid Two-Phase Flow Model for Stratified-Flow Pattern

2015 ◽  
Author(s):  
Carina N. Sondermann ◽  
Rodrigo A. C. Patrício ◽  
Aline B. Figueiredo ◽  
Renan M. Baptista ◽  
Felipe B. F. Rachid ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Numerical Study ◽  
Fluid Model ◽  
Practical Importance ◽  
Stratified Flow ◽  
Hyperbolic Partial Differential Equations ◽  
Two Phase ◽  
One Dimensional ◽  
Flow Models ◽  
Two Fluid

Two-phase flows in pipelines occur in a variety of processes in the nuclear, petroleum and gas industries. Because of the practical importance of accurately predicting steady and unsteady flows along the line, one-dimensional two-fluid flow models have been extensively employed in numerical simulations. These models are usually written as a system of non-linear hyperbolic partial-differential equations, but some of the available formulations are physically inconsistent due to a loss of the hyperbolicity property. In these cases, the associated eigenvalues become complex numbers and the model loses physical meaning locally. This paper presents a numerical study of a one-dimensional single-pressure four-equation two-fluid model for an isothermal stratified flow that occurs in a horizontal pipeline. The diameter, pressure and volume fraction are kept constant, whereas the liquid and gas velocities are varied to cover the entire range of superficial velocities in the stratified region. For each point, the eigenvalues are numerically computed to verify whether they are real numbers and to assess their signs. The results show that hyperbolicity is lost near the boundaries of the stratified pattern and in a vast area of the region itself. Moreover, the eigenvalue signs alternate, which has implications on the prescription of numerical boundary conditions.

Sign in / Sign up

Export Citation Format

Share Document