Validation Study for VOF Simulations of Boiling in a Microchannel

2015 ◽  
Author(s):  
Catherine Gorlé ◽  
Hyoungsoon Lee ◽  
Farzad Houshmand ◽  
Mehdi Asheghi ◽  
Kenneth Goodson ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Two Phase Flow ◽  
Fluid Simulation ◽  
Experimental Result ◽  
Base Temperature ◽  
Phase Flow ◽  
Two Phase ◽  
Fixed Temperature ◽  
Initial Development ◽  
Flux Boundary Condition

This paper presents a comparison of Volume-of-Fluid simulation results with experiments [1] for two-phase flow and heat transfer in a micro channel. Mass transfer between the phases is modeled using a reduced-order model, requiring the definition of a time relaxation constant, r. A two-step solution procedure is used, where first a fixed temperature boundary condition is imposed at the heater to avoid overheating of the device during the initial development of the two-phase flow. After obtaining a quasi-steady-state solution this is changed to a heat flux boundary condition to determine the final solution. Results using three different values for r indicate that the value of the constant should vary throughout the domain. A final simulation where r is defined as a function of the streamwise location results in a prediction of the base temperature within 1K of the experimental result, a pressure drop within 30%, and a prediction of the location of transition from subcooled to saturated flow within 2mm.

Experiment and Numerical Simulation of Bubble Behaviors in Argon Gas Injection Into Lead-Bismuth Pool

2006 ◽  
Author(s):  
Yumi Yamada ◽  
Toyou Akashi ◽  
Minoru Takahashi
Keyword(s):  
Direct Contact ◽  
Two Phase Flow ◽  
Experimental Result ◽  
Feed Water ◽  
Force Model ◽  
Phase Flow ◽  
Two Dimensional ◽  
Two Phase ◽  
Argon Gas ◽  
Bubble Rising

In a lead-bismuth alloy (45%Pb-55%Bi) cooled direct contact boiling water fast reactor (PBWFR), steam can be produced by direct contact of feed water with primary Pb-Bi coolant in the upper core plenum, and Pb-Bi coolant can be circulated by buoyancy forces of steam bubbles. As a basic study to investigate the two-phase flow characteristics in the chimneys of PBWFR, a two-dimensional two-phase flow was simulated by injecting argon gas into Pb-Bi pool in a rectangular vessel (400mm in length, 1500mm in height, 50mm in width), and bubble behaviors were investigated experimentally. Bubble sizes, bubble rising velocities and void fractions were measured using void probes. Argon gas was injected through five nozzles of 4mm in diameter into Pb-Bi at two locations. The experimental conditions are the pressure of atmospheric pressure, Pb-Bi temperatures of 443K, and the flow rate of injection Ar gas is 10, 20, and 30 NL/min. The measured bubble rising velocities were distributed in the range from 1 to 3 m/s. The average velocity was about 0.6 m/s. The measured bubble chord lengths were distributed from 1mm up to 30mm. The average chord length was about 7mm. An analysis was performed by two-dimensional and two-fluid model. The experimental results were compared with the analytical results to evaluate the validity of the analytical model. Although large diameter bubbles were observed in the experiment, the drag force model for spherical bubbles performed better for simulation of the experimental result because of high surface tension force of Pb-Bi.

scholarly journals Numerical Simulation of Gas-Liquid Two-Phase Flow in a Horizontally Placed Hydrophobic Rectangular Channel (Part 2, Influence of Abrupt Contraction)

2012 ◽  
Vol 31 (4-5) ◽  
pp. 411-413
Author(s):  
Y. Ueda ◽  
T. Nakajima ◽  
T. Ishii ◽  
R. Tsujino ◽  
M. Iguchi
Keyword(s):  
Two Phase Flow ◽  
Rectangular Channel ◽  
Experimental Result ◽  
Inertia Force ◽  
Phase Flow ◽  
Bubble Behavior ◽  
Fluid System ◽  
Two Phase ◽  
Preliminary Experimental Result ◽  
Abrupt Contraction

AbstractThis paper computationally visualizes two-phase flow patterns through a horizontally placed hydrophilic or hydrophobic rectangular channel with an abrupt contraction. The rectangular duct used in this study has a thickness narrower than the Laplace constant so that the surface tension governs the fluid system rather than the inertia force. In particular, the computed bubble behavior at the abrupt contraction seemed to be a similar nature against the preliminary experimental result.

Characteristics of Two-Phase Flow Pressure Drop of Propane in Horizontal Circular Small Tube

2016 ◽  
Vol 819 ◽  
pp. 371-375
Author(s):  
Agus Sunjarianto Pamitran ◽  
Sentot Novianto ◽  
T.A. Simanjuntak ◽  
Nasruddin ◽  
Muhammad Idrus Alhamid
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Saturation Temperature ◽  
Experimental Result ◽  
Phase Flow ◽  
Two Phase ◽  
Small Tube ◽  
Flow Pressure

This study experimentally investigated two-phase flow pressure drop of propane as refrigerant in horizontal small tube. Inner diameter and length of the tube were 7.6 mm and 1.07 m, respectively. In order to get pressure drop data, the experiment was conducted in various conditions of 10 to 25 kW m-2 heat flux, 200 to 628 kg m-2 s-1 mass flux, and 4.0 to 11.7°C saturation temperature. This study clearly showed the effect of heat flux, mass flux, and saturation temperature on the pressure drop of propane. This study also investigated which fluid properties gave higher effect on the frictional pressure drop due to its change over the process based on the recent experiment data. The existing pressure drop correlations were evaluated against the experimental result.

Experimental Characterization of Two-Phase Cold Plates Intended for High Density Data Center Servers Using a Dielectric Fluid

2021 ◽  
Author(s):  
Bharath Ramakrishnan ◽  
Cong Hiep Hoang ◽  
Sadegh Khalili ◽  
Yaser Hadad ◽  
Srikanth Rangarajan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Dielectric Fluid ◽  
Base Temperature ◽  
Phase Flow ◽  
Cold Plate ◽  
Two Phase ◽  
Cold Plates

Abstract High Performance Computing (HPC) data centers demand cutting edge cooling techniques like direct contact liquid cooling (DCLC) for safe and secure operation of their high-power density servers. Two-phase flow boiling heat transfer technique is widely believed to address the heating problem posed by HPC racks. In this study, a novel liquid cooled cold plate containing microchannel and jet impingement arrangement was characterized for its two-phase flow and thermal behavior. A sophisticated bench top setup involving a mock package was developed to carry out the experiments in a controlled fashion using a dielectric fluid Novec/HFE-7000. Two-phase flow boiling in cold plates which has a strong dependency on surface phenomena was carefully studied at various levels of inlet pressure, subcooling, flow rates and heat flux levels to the mock package. A resistance network was invoked to determine the average heat transfer coefficient at various exit qualities estimated by energy balance equation. While the results make it evident that, the high heat generating components can be kept at operable conditions using the two-phase cooling; a deeper insight at the outcomes could pave way for more energy efficient cold plate designs. The experiment was carried out with a large heated surface of 6.45 cm2 and maximum dissipated heat flux was around 63.6 W/cm2 corresponding to chip power of 410 W. Base temperature was kept below 75 oC and pressure drop did not exceed 21 kPa.

Frictional Pressure Drop and Two-Phase Flow Pattern of Gas-Liquid Two-Phase Flow in Circular and Rectangular Minichannels

2006 ◽  
Author(s):  
Hiroyasu Ohtake ◽  
Hideyasu Ohtaki ◽  
Yasuo Koizumi
Keyword(s):  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Experimental Result ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Circular Tubes ◽  
Rectangular Channels ◽  
Inner Diameter

The frictional pressure drops of gas-liquid two-phase flow in mini-pipes and mini-rectangular channels were investigated experimentally. The following test channels were used in the present experiments: commercial stainless-steel circular tubes with 0.6, 0.5 and 0.25 mm in inner diameter, FEP circular tube of 0.4 mm in inner diameter and rectangular channels, made of Acrylic resin, with 0.39 × 20.4 mm, 0.21 × 9.75 mm, 0.26 × 4.28 mm and 0.18 × 1.87 mm in height and width, respectively. The pressure drops of straight pipe, sudden enlargement and sudden contraction of gas-liquid two-phase flow in mini-pipes were measured for the test mini-channels. The pressure drops of rectangular minichannel were also measured. Experimental result showed that measured two-phase friction multipliers agreed well with a conventional Lockhart-Martinelli correlation for circular tubes and Mishima-Hibiki’s correlation for rectangular channels. Observed flow patterns by visualization were bubbly, slug, churn, ring and annular flow; the flow patterns in the present experiments were reproduced well by Baker’s flow pattern map.

Numerical Simulation on the Solidification of ZA27 Alloy by a Two-Phase Flow Model

2005 ◽  
Vol 475-479 ◽  
pp. 3203-3206
Author(s):  
Zhan Ling Zhang ◽  
Liu Shuan Yang ◽  
Feng Ni
Keyword(s):  
Flow Model ◽  
Two Phase Flow ◽  
Concentration Field ◽  
Solidification Process ◽  
Simulation Software ◽  
Fluid Simulation ◽  
Phase Flow ◽  
Two Phase ◽  
Za27 Alloy ◽  
Cylindrical Coordinate

ZA27 alloy solidifies in the way of paste-solidification, and results in gravity segregation. The two-phase flow model was developed on the basis of the solidification characteristic of the ZA 27 alloy. And the governing equations of the solidification process were differentiated and computed in a 3-D cylindrical coordinate system through a heat and fluid simulation software package (PHOENICS). The computation of the concentration field indicated a segregation of Al, and is in good agreement with the experiments. This model could simulate the convection and the gravitational segregation during the solidification.

Flow Configure in Vertical 180 Degree Turning Duct

2001 ◽  
Author(s):  
Lu Yuanwei ◽  
Zhou Fangde ◽  
Wang Yueshe ◽  
Qian Huanqun ◽  
Hu Zhihua
Keyword(s):  
Flow Pattern ◽  
Liquid Flow ◽  
Two Phase Flow ◽  
Vertical Tube ◽  
Experimental Result ◽  
Phase Flow ◽  
Two Phase ◽  
Vertical Part ◽  
Flow Situation ◽  
Gas Liquid Flow

Abstract Bend is applied in many industries, which exert an influence on fluid and make the flow complicate. The second flow caused by the bend is strong enough that the flow behind it very long can be affected, so it is hard to make the flow in it steady. The long-term unsteady flow can make the pipe fatigue, so make the tube crack and leak. It is important to improve this situation. In this paper a throttle is built in the exit of the bend to control the non-homogeneous flow inside the bend, which can overcome the disadvantage of bend in industrial application. Through computed the flow field behind the bend by water, we can see that the throttle can improve the flow situation and make the flow steady behind it. Applying this method to the gas-liquid flow, the experimental result showed that the void fraction behind the bend is alike the fully developed flow. It means that the throttle can improve the two-phase flow situation in the invert U bend. At last the gas-liquid flow pattern in-bend was studied by experiment and built the flow pattern map in the vertical parts of the invert U bend. It was found that the flow pattern in the vertical part of invert U bend is different from the fully developed gas-liquid flow in vertical tube. The throttle built in the bend make the unsteady region of two-phase flow being reduced.

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