Pressure drop and heat transfer analysis of flow boiling in a minichannel: influence of the inlet condition on two-phase flow stability

This paper addresses the numerical simulation of two-phase flow heat transfer in the helically coiled tubes of an integral type pressurized water reactor steam generator under normal operation using a computational fluid dynamics code. The shell-side flow field where a single-phase fluid flows in the downward direction is also calculated in conjunction with the tube-side two-phase flow characteristics. For the calculation of tube-side two-phase flow, the inhomogeneous two-fluid model is used. Both the Rensselaer Polytechnic Institute wall boiling model and the bulk boiling model are implemented for the numerical simulations of boiling-induced two-phase flow in a vertical straight pipe and channel, and the computed results are compared with the available measured data. The conjugate heat transfer analysis method is employed to calculate the conduction in the tube wall with finite thickness and the convections in the internal and external fluids simultaneously so as to match the fluid-wall-fluid interface conditions properly. Both the internal and external turbulent flows are simulated using the standard k-ε model. From the results of the present numerical simulation, it is shown that the bulk boiling model can be applied to the simulation of two-phase flow in the helically coiled steam generator tubes. In addition, the present simulation method is considered to be physically plausible in the light of discussions on the computed results.

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Numerical Simulation of Subcooled Flow Boiling Heat Transfer in Helical Tubes

Heat Transfer, Volume 2 ◽

10.1115/imece2006-14276 ◽

2006 ◽

Author(s):

Jong Chull Jo ◽

Woong Sik Kim ◽

Chang-Yong Choi ◽

Yong Kab Lee

Keyword(s):

Heat Transfer ◽

Numerical Simulation ◽

Steam Generator ◽

Two Phase Flow ◽

Flow Boiling ◽

Heat Transfer Analysis ◽

Normal Operation ◽

Phase Flow ◽

Two Phase ◽

Pressurized Water

This paper addresses the numerical simulation of two phase flow heat transfer in the helically coiled tubes of an integral type pressurized water reactor steam generator under normal operation using a CFD code. The single phase flow which flow downward direction in the shell side is also calculated together. For the calculation of tube side two-phase flow the inhomogeneous two-fluid model is used. Both the RPI (Rensselaer Polytechnic Institute) wall boiling model and the bulk boiling model are implemented for the numerical simulation and the computed results are compared with the available measured data. The conjugate heat transfer analysis method is employed to calculate the conduction in the tube wall with finite thickness and the convections in the internal and external fluids simultaneously so as to match the fluid-wall-fluid interface conditions properly. Both the internal and external turbulent flows are simulated using the standard k-ε model From the results of present numerical simulation, it is shown that the bulk boiling model can be applied to the simulation of two-phase flow in the helically coiled steam generator tubes. The results also show that the present simulation method is considered to be physically plausible when the computed results are compared with available previous experimental and numerical studies.

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Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

Journal of Electronic Packaging ◽

10.1115/1.1756589 ◽

2004 ◽

Vol 126 (3) ◽

pp. 288-300 ◽

Cited By ~ 16

Author(s):

Weilin Qu ◽

Seok-Mann Yoon ◽

Issam Mudawar

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Flow Pattern ◽

Two Phase Flow ◽

Flow Boiling ◽

Flow Patterns ◽

Heat Sinks ◽

Phase Flow ◽

Micro Channel ◽

Two Phase

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406×2.032mm2 cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Features unique to two-phase micro-channel flow were identified and employed to validate key assumptions of an annular flow boiling model that was previously developed to predict pressure drop and heat transfer in two-phase micro-channel heat sinks. This earlier model was modified based on new findings from the adiabatic two-phase flow study. The modified model shows good agreement with experimental data for water-cooled heat sinks.

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State-of-the-art of two-phase flow and flow boiling heat transfer and pressure drop of CO2 in macro- and micro-channels

International Journal of Refrigeration ◽

10.1016/j.ijrefrig.2005.07.005 ◽

2005 ◽

Vol 28 (8) ◽

pp. 1149-1168 ◽

Cited By ~ 72

Author(s):

John R. Thome ◽

Gherhardt Ribatski

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Boiling Heat Transfer ◽

Two Phase Flow ◽

State Of The Art ◽

Flow Boiling ◽

Phase Flow ◽

Two Phase ◽

Flow Boiling Heat Transfer ◽

Micro Channels

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Experimental Study of Heat Transfer, Pressure Drop, and Dryout for Flow Boiling of Water in an Oil Heated Minichannel

ASME 2nd International Conference on Microchannels and Minichannels ◽

10.1115/icmm2004-2387 ◽

2004 ◽

Cited By ~ 3

Author(s):

Levi A. Campbell ◽

Satish Kandlikar

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Test Section ◽

Two Phase Flow ◽

Flow Boiling ◽

Small Diameter ◽

Constant Heat Flux ◽

Phase Flow ◽

Two Phase ◽

Mass Fluxes

Heat transfer and pressure drop, are experimentally recorded for flow boiling water in a single 706 μm circular copper channel 158.75 mm long. Heat is supplied by heat transfer oil at specified temperatures to a helical channel in the test section. In contrast to other current experimental techniques for flow boiling in small diameter tubes, a uniform temperature boundary condition is employed rather than a constant heat flux condition. The principal results of these experiments are two-phase flow boiling heat transfer rates and an analysis of the time-dependent pressure drop signature during two-phase flow in a minichannel. The range of experiments includes mass fluxes of 43.8–3070 kg/m2s and wall temperatures of 100°C–171.2°C. In all cases the test section water inlet is subcooled to between 72.9°C and 99.6°C. The inlet pressures used are 1.1–230.5 kPa (gage).

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