Characterization of Convection Patterns During the Solidification Process Using Particle Image Velocimetry

2003 ◽  
Author(s):  
C. Ghenai ◽  
R. K. Duggirala ◽  
C. X. Lin ◽  
M. A. Ebadian
Keyword(s):  
Particle Image Velocimetry ◽  
Temperature Distribution ◽  
Ammonium Chloride ◽  
Particle Image ◽  
Vertical Wall ◽  
Solidification Process ◽  
Convection Flow ◽  
Initial Concentration ◽  
Image Velocimetry ◽  
Convection Patterns

This experimental study focused mainly on the solidification of a binary mixture of ammonium chloride and water (NH4Cl-H2O) in a differentially heated cavity. One vertical wall is cooled at temperature TC, and the opposite vertical wall is kept at constant temperature TH = +20°C. The effect on the solidification process of the initial concentration of ammonium chloride and cooling conditions is examined. Particle image velocimetry (PIV) is used for the visualization of the dynamic field during the solidification process. The temperature distribution at discrete locations in the solution and on the vertical cooling wall was monitored using thermocouples. The convection flow patterns, the ice thickness, and the temperature distribution were obtained for various initial concentrations of ammonium chloride ranging from 0wt% to 20wt% (sub-eutectic and near-eutectic growth). The convection patterns obtained for different initial concentrations showed significant differences. The results showed that the process of solidification is slower with an increase in the initial concentration levels of the binary solution. The ice growth rate was almost double at the bottom of the cavity.

Experimental Investigation of Fluid Flow and Phase Moving Interface During the Solidification of Binary Mixture in Trapezoidal Cavity

Volume 3 ◽  
2004 ◽  
Author(s):  
C. Ghenai ◽  
R. K. Duggirala ◽  
C. X. Lin ◽  
M. A. Ebadian
Keyword(s):  
Ammonium Chloride ◽  
Binary Solution ◽  
Solidification Process ◽  
Convection Flow ◽  
Initial Concentration ◽  
Moving Interface ◽  
Image Velocimetry ◽  
Convection Patterns ◽  
Solid Liquid Interface ◽  
Solid Liquid

This experimental study focuses on the solidification of a ammonium chloride-water (NH4Cl-H2O) solution in a trapezoidal cavity with one and two vertical cooling walls. The effect of the initial concentration of ammonium chloride (sub-eutectic: f < 19.8% and eutectic f = 19.8%, where f is the percentage in weight) and boundary temperatures (Tcold = −30°C to −10°C) on the solidification process is examined. Particle Image Velocimetry (PIV) is used in this study to measure the velocity fields in the melt during the solidification process. The temperatures distributions at discrete locations in the solution and the boundary walls were measured by 32 thermocouples. The convection flow patterns; the ice shape and thickness; the velocity of the moving liquid/solid interface; and the temperature distribution were obtained. The convection patterns obtained for different initial concentrations showed significant differences. The results showed that the process of solidification is slower with an increase in the initial concentration levels of the binary solution. The growth rate of the frozen layer, the velocity of the moving solid-liquid interface and the temperature in the melt was significantly reduced when increasing the initial concentration of ammonium chloride.

PIV Analysis of the Flow Pattern Around an Ablation Catheter to Observe the Flow Effect on the Electrode

2013 ◽  
Author(s):  
Kaihong Yu ◽  
Tetsui Yamashita ◽  
Shigeaki Shingyochi ◽  
Kazuo Matsumoto ◽  
Makoto Ohta
Keyword(s):  
Blood Flow ◽  
Particle Image Velocimetry ◽  
Catheter Ablation ◽  
Flow Pattern ◽  
Open Channel ◽  
Particle Image ◽  
Circulation System ◽  
Convection Flow ◽  
Image Velocimetry ◽  
Catheter Tip

Radiofrequency (RF) catheter ablation is a highly effective treatment for many cardiac arrhythmias, especially for tachyarrhythmia. RF energy is introduced through the catheter onto the endocardial surface to destroy the abnormal heart tissue causing the heart rhythm disorder. Many parameters relate to myocardial temperature, such as RF power, tissue contact, and blood flow. Blood flow is an important factor that has a cooling effect on myocardium and affects the final lesion size. Many previous studies have shown that under temperature control, lesion sizes are larger and tissue temperatures rise faster with a high flow rate. If the flow causes a decrease in the temperature of the catheter tip, the generator will increase the power output to maintain the tip at a constant temperature. However, few studies of RF catheter ablation have investigated how ablation affects blood flow. Observation of the flow pattern around the catheter can help to determine the mechanism of the flow effects on the temperature of the catheter tip. The purpose of this study is to observe the flow pattern during ablation using an in-vitro circulation system developed for Particle Image Velocimetry (PIV). We developed an open-channel circulation system to simulate blood flow. The mold for the open-channel was built with acrylic boards for transparency. The working fluid was 0.9% saline, which was used at room temperature (20°C). Instead of animal myocardium, we used a poly (vinyl alcohol) hydrogel (PVA-H), which has mechanical characteristics that approximate those of biological soft tissue, and contact with the PVA-H surface by the catheter is similar to that with myocardium. A 7 Fr catheter with a 4-mm ablation electrode tip was set perpendicular to the PVA-H surface, and the contact weight between the electrode of the catheter and the PVA-H surface was 2.2 gf. To measure the temperature profile in the PVA-H, a K-type thermocouple with the diameter of 0.5 mm was placed at the depth of 2 mm from the surface. The thermocouple tip was always placed on the catheter axis. The flow pattern at the location where the catheter was held was observed by a high speed camera, and the resulting images were analyzed by particle image velocimetry (PIV). The results showed that in the absence of applied flow, convection flow from the electrode is observed in the areas around the catheter. However, under a 1.6 L/min flow rate, convection flow disappears. In conclusion, blood flow could decrease the catheter tip temperature, and the influence of ablation in the flow around the catheter disappeared.

scholarly journals Experimental and numerical investigation of coolant mixing in a model of reactor pressure vessel down-comer and in cold leg inlets

2017 ◽  
Vol 21 (3) ◽  
pp. 1491-1502 ◽  
Author(s):  
Ezddin Hutli ◽  
Valer Gottlasz ◽  
Istvanne Farkas ◽  
Gyorgy Ezsol ◽  
Gabor Baranyai
Keyword(s):  
Particle Image Velocimetry ◽  
Temperature Distribution ◽  
Thermal Fatigue ◽  
Pressure Vessel ◽  
Particle Image ◽  
Laser Induced Fluorescence ◽  
Mixing Process ◽  
Image Velocimetry ◽  
Pressurized Thermal Shock ◽  
Reactor Pressure

Thermal fatigue and pressurized thermal shock phenomena are the main problems for the reactor pressure vessel and the T-junctions both of them depend on the mixing of the coolant. The mixing process, flow and temperature distribution has been investigated experimentally using particle image velocimetry, laser induced fluorescence, and simulated by CFD tools. The obtained results showed that the ratio of flow rate between the main pipe and the branch pipe has a big influence on the mixing process. The particle image velocimetry/planar laser-induced fluorescence measurements technologies proved to be suitable for the investigation of turbulent mixing in the complicated flow system: both velocity and temperature distribution are important parameters in the determination of thermal fatigue and pressurized thermal shock. Results of the applied these techniques showed that both of them can be used as a good provider for data base and to validate CFD results.

The Influence of Boundary Condition on Solidification of Binary Solution in Rectangular Cavity

1999 ◽  
Author(s):  
N. Pradeep ◽  
H. J. Kang ◽  
C. X. Lin ◽  
M. A. Ebadian
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Binary Solution ◽  
Solidification Process ◽  
Heat Transfer Process ◽  
Bottom Surface ◽  
Piv Technique ◽  
Image Velocimetry

Abstract The solidification of a binary mixture of ammonium chloride and water flow cooling in rectangular cavities was investigated experimentally under different boundary conditions. Two cavities measuring 63.5 × 180 × 165 mm and 76 × 120 × 96 mm were employed in this study. For the first cavity, its three surfaces (i.e., two side surfaces and one bottom surface) were cooled. For the second cavity, however, only two side surfaces were cooled (i.e., the bottom surface was adiabatic). The influence of the change of boundary was studied. All investigations were carried out in the surface temperature range from −15 to −30°C under a constant refrigerant temperature of −22°C. The effect of cooling boundary condition had a great effect on the heat transfer process during the solidification process. The advanced Particle Image Velocimetry (PIV) technique was used to catch the velocity profiles during the solidification process.

Effect of Boundary Conditions and Initial Concentrations on the Solidification of Binary Mixture in Trapezoidal Cavity

2004 ◽  
Author(s):  
R. K. Duggirala ◽  
P. Sirpal ◽  
C. X. Lin ◽  
C. Ghenai
Keyword(s):  
Binary Mixture ◽  
Boundary Conditions ◽  
Ammonium Chloride ◽  
Solidification Rate ◽  
Heat Rate ◽  
Solidification Process ◽  
Eutectic Growth ◽  
Convection Flow ◽  
Rate Condition ◽  
Initial Concentration

The solidification of binary mixture (NH4Cl–H2O) inside a trapezoidal cavity is investigated experimentally in this study. The experiments are carried out in a trapezoidal cavity measuring 65 mm × 130 mm × 150 mm with inclined angle of 69°. Solidification of ammonium chloride occurs on the left inclined copper wall held under constant heat rate condition while the other walls are maintained at adiabatic conditions. Particle image velocimetry was used in this study for visualization of the dynamic field during the solidification process. The temperatures of the solution inside the cavity and the boundary walls were measured by 32 thermocouples during the solidification process. Convective flow field, temperature distribution and frozen layer thickness were obtained for different initial concentrations of ammonium chloride varying from 0 to 19.8 % (sub-eutectic and near-eutectic growth) and various boundary conditions (Tcold = −30 °C to 0 °C). The results obtained in the course of study reveal that (1) the solidification rate is higher during initial stages of the solidification process, (2) the process of solidification is slower with increase in the initial concentration levels of the ammonium chloride and (3) the initial concentration play a significant role in the evolution of convection flow patterns.

Experimental Investigations Into Mixed Convection About a Horizontal Cylinder: Part B — Fluid Dynamics Using Particle Image Velocimetry

2005 ◽  
Author(s):  
Vanessa Egan ◽  
Tara Dalton ◽  
Mark R. D. Davies
Keyword(s):  
Particle Image Velocimetry ◽  
Fluid Flow ◽  
Flow Field ◽  
Mixed Convection ◽  
Particle Image ◽  
Reynolds Numbers ◽  
Experimental Investigations ◽  
Convection Flow ◽  
Flow Visualisation ◽  
Image Velocimetry

The second of two papers investigating mixed convection about a cylinder in the buoyancy opposing cross flow regime. The experimental configuration is essentially the same as that used in part A, [1]. Particle image velocimetry (PIV) is used to measure the fluid flow at Reynolds numbers in the range of 32 to 89 and Rayleigh numbers of 1.7E+04 and 2.4E+04. Fluid flow results are shown in the form of instantaneous vector plots with corresponding flow visualisation images, streamline plots and velocity vector plots. The presence of the opposing flow created an unsteady flow field about the cylinder at lower Reynolds numbers while increasing the Reynolds number resulted in the development of a steady flow field tending towards that of a forced convection flow. An increase in Rayleigh number led to an increase the instability of the flow field. The velocity field results were found to compliment the heat transfer investigation detailed in part A, [1].

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