scholarly journals CFD SIMULATION OF UPWARD SUBCOOLED BOILING FLOW OF FREON R12

2016 ◽  
Vol 4 ◽  
pp. 73
Author(s):  
Tomas Romsy ◽  
Pavel Zacha
Keyword(s):  
Cfd Simulation ◽  
Flow Boiling ◽  
Heat Removal ◽  
Industrial Applications ◽  
Test Facility ◽  
Water Mixture ◽  
Ansys Fluent ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Boiling Flow

Subcooled flow boiling under forced convection occurs in many industrial applications of purpose to maximize heat removal from the heat source by the very large heat transfer coefficient. This work deals with CFD simulations of the subcooled flow boiling of refrigerant R12 solved by code ANSYS FLUENT r16. The main objective of this paper is verification of used numerical settings on relevant experiments performed on DEBORA test facility. Also comparisons with previously provided simulation on NRI Rez are presented. Data outputs from this work are basis to subsequent calculations of steam-water mixture cooling of Pb-Li eutectic.

Numerical investigation of the effect of bump and indent inside a vertical tube on the subcooled flow boiling and critical heat flux

2020 ◽  
Vol 14 (2) ◽  
pp. 6690-6708
Author(s):  
Kianoush DolatiAsl ◽  
Ehsan Abedini ◽  
Younes Bakhshan
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Volume Fraction ◽  
Flow Boiling ◽  
Vapour Phase ◽  
Vertical Tube ◽  
Ansys Fluent ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Euler Model

One of the essential industry problems is the critical heat flux (CHF) phenomenon in the flow boiling regime which leads to the temperature jumping and damaging to the systems. Increasing the vapour volume fraction decreases the heat transfer coefficient, and finally, temperature jump will occur. Also, the existence of the bumps and indent in the flow domain changes the flow pattern. In this study, by considering bumps and indent in the tube, the boiling of fluid flow in the vertical tube is discussed. For modelling and simulating the problems, the Euler-Euler model for studying the interaction of the liquid-vapour phases was used. Some models and material specifications are declared using the user-defined function (UDF) codes to the ANSYS Fluent program. The results show that the existence of bumps and indent inside the tube causes the flow of liquid phase to be less redirected in comparison to vapour phase flow due to having more momentum; therefore, at the end of the bumps in the tube, the amount of vapour volume fraction near the wall rises sharply. By increasing the flow mass flux, the vapour volume fraction at the end of bumps increases which lead to decreasing CHF value. It has also observed that if there are bumps and indents inside the tube, there will be no significant change in the liquid flow and vapour volume fraction in the other parts of the tube, as compared to the regular tube.    

Some Measurements in Subcooled Flow Boiling of Refrigerant-113

1991 ◽  
Vol 113 (1) ◽  
pp. 216-223 ◽  
Author(s):  
A. Hasan ◽  
R. P. Roy ◽  
S. P. Kalra
Keyword(s):  
Flow Boiling ◽  
Fluid Model ◽  
Annular Channel ◽  
Heated Wall ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Boiling Flow ◽  
Phase Temperature ◽  
Two Fluid Model ◽  
Two Fluid

Measurements of local vapor phase residence time fraction, liquid phase temperature, and heated wall temperature were carried out in subcooled flow boiling of Refrigerant-113 through a vertical annular channel. Data are reported for two fluid mass velocities and two pressures over a range of wall heat flux. Estimates of typical vapor bubble size and velocity are given. Some comparisons with a one-dimensional two-fluid model of subcooled boiling flow are also presented.

scholarly journals Interface Tracking Simulation for Subcooled Flow Boiling Using VOSET Method

2021 ◽  
Vol 8 ◽  
Author(s):  
Kong Ling ◽  
Shuai Zhang ◽  
Wenxing Liu ◽  
Xiaowei Sui ◽  
Wenquan Tao
Keyword(s):  
Heat Transfer ◽  
Volume Fraction ◽  
Flow Boiling ◽  
Bubbly Flow ◽  
Interface Tracking ◽  
Time Averaging ◽  
Subcooled Flow Boiling ◽  
Moving Interface ◽  
Subcooled Flow ◽  
Boiling Flow

This article presents a numerical simulation on subcooled flow boiling at a high-pressure condition. An interface tracking method, VOSET, was used to handle the moving interface, and conjugate heat transfer between the wall and the fluid was included in the numerical model. In order to consider the evaporation on the microlayer below a growing bubble, a depletable micorlayer model was employed. Our simulation illustrated typical processes of subcooled boiling flow including bubble sliding, coalescence, detachment and annihilation, and revealed many mechanisms in increasing the heat transfer coefficient. A transition in flow regime from isolated bubbly flow to elongated bubbly flow was reproduced by our simulations. The void fraction obtained by time-averaging the volume fraction of the vapor phase under various flow conditions was analyzed.

Void Fractions in Subcooled Flow Boiling

1969 ◽  
Vol 91 (4) ◽  
pp. 471-476 ◽  
Author(s):  
P. S. Larsen ◽  
L. S. Tong
Keyword(s):  
Heat Transfer ◽  
Flow Boiling ◽  
Heated Surface ◽  
Liquid Core ◽  
Heat Removal ◽  
Two Phase ◽  
Subcooled Flow Boiling ◽  
Void Fractions ◽  
Subcooled Flow ◽  
The Difference

A semianalytic model is presented for the prediction of void fractions in subcooled flow boiling at elevated pressures. The model is based on the formation and growth of a bubble boundary layer adjacent to the heated surface at a rate determined by the difference between the imposed surface heat transfer and the heat removal capability of the subcooled liquid core of the flow. The latter heat transfer rate is determined by the analogy between heat and momentum transfer in the liquid employing empirical friction-factor data for low-quality two-phase flow. The analysis is compared to experimental results.

Experimental Investigation of Nucleate Boiling on Capillary Tubes Under PWR Specific Subcooling and Flow Parameters

2012 ◽  
Author(s):  
C. Schneider ◽  
R. Hampel ◽  
A. Traichel ◽  
A. Hurtado ◽  
S. Meissner ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Experimental Investigation ◽  
Critical Heat Flux ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Test Facility ◽  
High Heat Flux ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow

During full power operation of Pressurized Water Reactors (PWR), heat transfer phenomena of subcooled nucleate boiling may occur on the surface of the fuel rods. Despite high subcooling, this behavior results from the high heat flux up to 100 W/cm2 where vapor bubbles condensate when they are detached from the rod surface. In case of an accident with disturbance of cooling during transition from bubble to film boiling the critical heat flux (CHF) can be reached. This paper outlines the experimental investigation of heat transfer during subcooled flow boiling on a capillary tube. To investigate the heat transfer processes under these boiling conditions, a test facility for flow boiling with access for optical measuring methods was constructed. The temperature is measured with a thermocouple inside the tube while boiling bubbles are generated on the outside. For different subcooling and flow velocity the heat flux is increased in a range from zero up to approximately 115 W/cm2. The major aims of these investigations are to generate a database for modeling of these dependencies in computational fluid dynamic (CFD) codes and enhance the knowledge of phenomenological effects of subcooled flow boiling. This provides a contribution for the prediction of the critical heat flux with simulation codes.

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