Mixing of Two Streams, Steam and Water, in a Converging Nozzle

2000 ◽  
Author(s):  
Hikmet S. Aybar
Keyword(s):  
Single Phase ◽  
Cold Water ◽  
Chemical Processing ◽  
Contact Heat ◽  
Velocity Difference ◽  
One Dimensional ◽  
Water Flows ◽  
Contact Heat Transfer ◽  
Energy Equations ◽  
Two Fluid

Abstract Mixing of two fluid streams can be seen in many applications in chemical processing and energy generation industries. The supersonic steam blows into the cold water in the mixing nozzle. When the steam condenses, steam transfers to water heat and mass (because of the temperature difference and condensation) and momentum (because of the velocity difference). The condensation should be fully completed before the end of mixing nozzle. Thus, the length of the mixing nozzle is important parameter. After the condensation is completed, the flow is single phase, that is, liquid water, and the subsonic water flows in the converging nozzle. In this study, the mixing of the supersonic steam and subsonic water in a converging nozzle is investigated. The problem is modeled using one-dimensional continuity, momentum and energy equations, and solved numerically. For the calculation of the rate of condensation, a correlation for the contact heat transfer coefficient is used.

Stability of Single-Phase Natural Circulation With Inverted U-Tube Steam Generators

1988 ◽  
Vol 110 (3) ◽  
pp. 735-742 ◽  
Author(s):  
J. Sanders
Keyword(s):  
Mathematical Model ◽  
Single Phase ◽  
Flow Direction ◽  
Natural Circulation ◽  
Boussinesq Equations ◽  
Test Facility ◽  
Normal Flow ◽  
Steam Generators ◽  
One Dimensional ◽  
Water Flows

For natural circulation it is shown that parallel flow in the tubes of an inverted U-tube steam generator can be, at certain power levels, unstable. A mathematical model, based on one-dimensional Oberbeck-Boussinesq equations, shows that stability can be attained if in some tubes the water flows backward, opposite to the normal flow direction. The results are compared to measurements obtained from the natural circulation test A2-77A in the LOBI-MOD2 integral system test facility.

Water Hammer Simulation Capabilities With CATHENA

2009 ◽  
Author(s):  
Thomas Beuthe
Keyword(s):  
Single Phase ◽  
Water Hammer ◽  
Two Phase ◽  
Simulation Code ◽  
One Dimensional ◽  
Fluid Network ◽  
Two Component ◽  
Current Water ◽  
Two Fluid ◽  
Current Code

This paper summarizes the current water hammer simulation capabilities of the CATHENA one-dimensional two-fluid network thermalhydraulics simulation code. The single-phase and one- and two-component two-phase capabilities for simulating void collapse water hammer and water hammer in the presence of noncondensables is discussed. Recent successful efforts to resolve nodalization-dependence observed in the simulation of condensation-induced water hammer are presented along with efforts to develop condensation relationships for simulating condensation-induced water hammer. A summary of current code coupling capabilities is also presented. Possible future efforts to simulate water hammer at supercritical pressures as well as the coupling of CATHENA to piping stress codes are discussed.

scholarly journals Non-contact heat transfer models identification for laser hyperthermia of semi-transparent materials

2021 ◽  
Vol 2119 (1) ◽  
pp. 012147
Author(s):  
D S Semenov ◽  
A V Nenarokomov
Keyword(s):  
Heat Transfer ◽  
Thermal Effects ◽  
Transfer Problem ◽  
Contact Heat ◽  
One Dimensional ◽  
Contact Heat Transfer ◽  
Inverse Heat Transfer ◽  
Inverse Heat Transfer Problem ◽  
Laser Hyperthermia ◽  
Unsteady Heating

Abstract The identification of mathematical models of heat transfer traditionally involves the installation of temperature sensors inside the sample under study and registration of the response to external thermal effects. In cases where the use of contact methods for measuring temperature is impossible, it is necessary to develop new approaches to determining the unknown thermophysical and radiation-optical characteristics. Laser hyperthermia of superficial tissues is one such case. The paper proposes a method for identifying a model of one-dimensional unsteady heating of a semitransparent sample using non-contact thermometry. A feature of the physical process under consideration is the possibility of its discretization. Due to this, a two-stage iterative procedure for solving the inverse heat transfer problem was formulated. The implementation of the proposed algorithm using software made it possible to carry out a computational experiment. The results showed the effectiveness of this approach. The presented method can be used in the development of means for monitoring and regulating the laser hyperthermia procedure.

Hydrodynamic Features of Contact Heat-Transfer Packing Devices

1997 ◽  
Vol 28 (4-6) ◽  
pp. 393-397
Author(s):  
N. Yu. Koloskova ◽  
V. V. Dubrovskaya ◽  
V. V. Orlyanskii
Keyword(s):  
Heat Transfer ◽  
Contact Heat ◽  
Contact Heat Transfer

A time-dependent model for high-pressure discharges in narrow ablative capillaries

1993 ◽  
Vol 50 (1) ◽  
pp. 51-70 ◽  
Author(s):  
D. Zoler ◽  
S. Cuperman ◽  
J. Ashkenazy ◽  
M. Caner ◽  
Z. Kaplan
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Time Dependent ◽  
Dimensional Model ◽  
Plasma Sources ◽  
One Dimensional ◽  
Space And Time ◽  
Dependent Model ◽  
Energy Equations ◽  
Time Dependent Model

A time-dependent quasi-one-dimensional model is developed for studying high- pressure discharges in ablative capillaries used, for example, as plasma sources in electrothermal launchers. The main features of the model are (i) consideration of ablation effects in each of the continuity, momentum and energy equations; (ii) use of a non-ideal equation of state; and (iii) consideration of space- and time-dependent ionization.

Sign in / Sign up

Export Citation Format

Share Document