Experimental and Numerical Studies of Heat Transfer in Human Uteri During Cryoablation

2002 ◽  
Author(s):  
Jim S. Chen ◽  
Kevin Agnissey ◽  
Marla Wolfson ◽  
Charles Philips ◽  
Thomas Shaffer
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Temperature History ◽  
Rubber Sheet ◽  
Numerical Studies ◽  
Numerical Predictions ◽  
Silicone Rubber Sheet ◽  
Nicolson Scheme ◽  
Sheet Good ◽  
Good Agreement

This paper presents experimental and numerical studies of transient heat transfer inside the uterus during application of a PFC (perfluorochemical) fluid into the endometrium cavity in order to achieve cryoablation. The numerical prediction is based on a 1-D finite difference method of the bio-heat equation using the Crank Nicolson scheme. The numerical method is first validated by a 1-D physical model by measuring temperature history at several locations within a silicone rubber sheet. Good agreement, thus positive predictability, was obtained by comparing numerical predictions with the experimental data obtained from eight intact, hysterectomized uteri during cryoablation.

Analysis of Heat Transfer and Fluid Flow Through a Spirally Fluted Tube Using a Porous Substrate Approach

1994 ◽  
Vol 116 (3) ◽  
pp. 543-551 ◽  
Author(s):  
Vijayaragham Srinivasan ◽  
Kambiz Vafai ◽  
Richard N. Christensen
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Porous Substrate ◽  
The Finite Element Method ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Numerical Predictions ◽  
Friction Factors ◽  
Flow Through ◽  
Good Agreement

An innovative approach was opted for modeling the flow and heat transfer through spirally fluted tubes. The model divided the flow domain into two regions. The flutes were modeled as a porous substrate with direction-dependent permeabilities. This enabled modeling the swirl component in the fluted tube. The properties of the porous substrate such as its thickness, porosity, and ratio of the direction-dependent permeabilities were obtained from the geometry of the fluted tube. Experimental data on laminar Nusselt numbers and friction factors for different types of fluted tubes representing a broad range of flute geometry were available. Experimental data from a few of the tubes tested were used to propose a relationship between the permeability of the porous substrate and the flute parameters, particularly the flute spacing. The governing equations were discretized using the Finite Element Method. The model was verified and applied to the other tubes in the test matrix. Very good agreement was found between the numerical predictions and the experimental data.

Full 3D Conjugate Heat Transfer Simulation and Heat Transfer Coefficient Prediction for the Effusion-Cooled Wall of a Gas Turbine Combustor

2008 ◽  
Author(s):  
Andreas Jeromin ◽  
Christian Eichler ◽  
Berthold Noll ◽  
Manfred Aigner
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Gas Turbine ◽  
Conjugate Heat Transfer ◽  
Solid Wall ◽  
Heat Fluxes ◽  
Computational Domain ◽  
Transfer Coefficients ◽  
Wall Functions ◽  
Numerical Predictions

Numerical predictions of conjugate heat transfer on an effusion cooled flat plate were performed and compared to detailed experimental data. The commercial package CFX® is used as flow solver. The effusion holes in the referenced experiment had an inclination angle of 17 degrees and were distributed in a staggered array of 7 rows. The geometry and boundary conditions in the experiments were derived from modern gas turbine combustors. The computational domain contains a plenum chamber for coolant supply, a solid wall and the main flow duct. Conjugate heat transfer conditions are applied in order to couple the heat fluxes between the fluid region and the solid wall. The fluid domain contains 2.4 million nodes, the solid domain 300,000 nodes. Turbulence modeling is provided by the SST turbulence model which allows the resolution of the laminar sublayer without wall functions. The numerical predictions of velocity and temperature distributions at certain locations show significant differences to the experimental data in velocity and temperature profiles. It is assumed that this behavior is due to inappropriate modeling of turbulence especially in the effusion hole. Nonetheless, the numerically predicted heat transfer coefficients are in good agreement with the experimental data at low blowing ratios.

Post-Test Investigations of BFBT Critical Power Tests With Trace

2009 ◽  
Author(s):  
Marc Thieme ◽  
Wolfgang Tietsch ◽  
Rafael Macian ◽  
Victor Hugo Sanchez Espinoza
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Critical Power ◽  
The Core ◽  
Fine Mesh ◽  
The Us ◽  
Post Test ◽  
Trace Model ◽  
Good Agreement ◽  
Transfer Models

The validation of heat transfer models of safety analysis codes such as TRACE is very important due to the strong interaction of the thermal hydraulics parameters with the core neutronics. TRACE is the reference system code of the US NRC for LWR. It is being developed and extensively validated within the international CAMP-program. In this paper, the validation of heat transfer models of TRACE related to the prediction of the critical power is presented. The validation is based on a large number of critical power tests performed in the NUPEC BFBT (BWR Full-Size Fine-Mesh Bundle Tests) facility in Japan. These tests were analysed with the TRACE Version 5 RC 2. The comparison of predictions with the experimental data shows good agreement. The developed TRACE model and the comparison of experimental data with code results will be presented and discussed.

Leading-Edge Film-Cooling Physics: Part II — Heat Transfer Coefficient

2002 ◽  
Author(s):  
William D. York ◽  
James H. Leylek
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Leading Edge ◽  
Numerical Predictions ◽  
Validation Experiment ◽  
Computational Methodology ◽  
Near Wall

A comprehensive study of film cooling on a turbine airfoil leading edge was performed with a documented, well-tested computational methodology. In this paper, numerically predicted heat transfer coefficients on the film-cooled leading edge are compared with experimental data from the open literature. The results are presented as the ratio of heat transfer coefficient with film cooling to that without film cooling, and the physics behind the surface results are discussed. The leading edge model was a half-cylinder in shape with a bluff afterbody to match the validation experiment, and other geometric parameters matched those of Part I of this study. Coolant at a density equal to that of the mainstream flow was injected through three rows of cylindrical film-cooling holes. One row of holes was centered on the stagnation line of the cylinder, and the other two rows were located ±3.5 hole diameters off stagnation. The downstream rows were staggered such that they were centered laterally between holes in the stagnation row. The holes were inclined at 20° with the surface, and made a 90° angle with the streamwise direction (radial injection). Four average blowing ratios were simulated in the range of 0.75 to 1.9, corresponding to the same momentum flux ratios as in Part I of this work. The multi-block, unstructured numerical grid was characterized by high quality and density, especially in the near wall region, in order to minimize error in predictions of the heat transfer. A fully-implicit scheme was used to solve the steady Reynolds-averaged Navier-Stokes equations, and a realizable k-ε model provided turbulence closure. A two-layer near-wall treatment allowed the resolution of the viscous sublayer for maximum accuracy in the prediction of the wall heat transfer coefficient. The numerical predictions exhibited generally good agreement with experimental data. The heat transfer coefficient was observed to increase sharply aft of the holes in the downstream rows. When coupled with the adiabatic effectiveness results of the first paper in this series, it is evident that a systematic computational methodology may be effectively applied to investigate and understand the complicated leading edge film-cooling problem.

Coupled CFD-ANN Procedure for Extending Heat Transfer Correlations Out of Their Range of Validity

2012 ◽  
Author(s):  
Andrea Viano ◽  
Gabriele Ottino ◽  
Luca Ratto ◽  
Giuseppe Spataro
Keyword(s):  
Neural Network ◽  
Heat Transfer ◽  
Experimental Data ◽  
Nusselt Number ◽  
Gas Turbine ◽  
Training Session ◽  
Nonlinear Problems ◽  
Artificial Neural ◽  
Cfd Analyses ◽  
Good Agreement

The heat transfer coefficient and pressure losses are among the main parameters to be evaluated in gas turbine cooling network design. Due to the complexity of these estimates, correlation-based computations are typically used as a result of time-consuming and expensive experimental activities. One of the main problems that the industry has to face is that these correlations, based on non-dimensional experimental data, produce reliable results in a range of validity typically different from that encountered in gas turbine applications. This paper will present preliminary results of an innovative procedure based on CFD analyses and Artificial Neural Networks, able to extend correlation predictions out of their range of validity, without any additional experimental data. Well-known test cases were replicated by building corresponding CAD geometries which were discretized by means of appropriate meshes, resulting from grid-independence studies. CFD analyses, based on the RANS approach, were performed to overlay the computations of the Nusselt number obtained from experimental activities. A preliminary comparison among turbulence models was carried out to find one leading to a good agreement with the experimental data. Then, an optimization method, based on Evolutionary Algorithms, was applied to the CFD analyses in order to find the best set of constant values for the chosen turbulence model, leading to the most accurate prediction of the experimental dataset. The resulting ad hoc CFD model was adopted in order to analyse test case configurations characterized by parameters within and external to the correlation validity field, building a sufficiently wide feeding database. A feed-forward multi-layer neural network was selected among network architectures typically used in engineering applications for prediction analyses. ANNs were chosen because they enable the solution of these complex nonlinear problems by using simple computational operations. The selected Artificial Neural Network was trained by a back-propagation procedure on the CFD results regarding Nusselt number. The validation of the resulting ANN was performed comparing its outputs with experimental data external to the correlation range of validity, which had not been used in the training session. Good agreement has been found. Results are presented and discussed.

Analysis of Thermal Effects in Hydrodynamic Bearings

1986 ◽  
Vol 108 (2) ◽  
pp. 219-224 ◽  
Author(s):  
R. Boncompain ◽  
M. Fillon ◽  
J. Frene
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Effects ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Heat Transfer Equation ◽  
Reversed Flow ◽  
Theoretical Results ◽  
Generalized Reynolds Equation ◽  
Good Agreement

A general THD theory and a comparison between theoretical and experimental results are presented. The generalized Reynolds equation, the energy equation in the film, and the heat transfer equation in the bush and the shaft are solved simultaneously. The cavitation in the film, the lubricant recirculation, and the reversed flow at the inlet are taken into account. In addition, the thermoelastic deformations are also calculated in order to define the film thickness. Good agreement is found between experimental data and theoretical results which include thermoelastic displacements of both the shaft and the bush.

Computation of Flow and Heat Transfer in Two-Pass Channels With 60 deg Ribs

2001 ◽  
Vol 123 (3) ◽  
pp. 563-575 ◽  
Author(s):  
Yong-Jun Jang ◽  
Hamn-Ching Chen ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Moment Closure ◽  
Closure Model ◽  
Second Moment ◽  
Flow And Heat Transfer ◽  
Numerical Predictions ◽  
Sharp Turn ◽  
Second Moment Closure ◽  
Near Wall

Numerical predictions of three-dimensional flow and heat transfer are presented for a two-pass square channel with and without 60 deg angled parallel ribs. Square sectioned ribs were employed along one side surface. The rib height-to-hydraulic diameter ratio e/Dh is 0.125 and the rib pitch-to-height ratio (P/e) is 10. The computation results were compared with the experimental data of Ekkad and Han [1] at a Reynolds number (Re) of 30,000. A multi-block numerical method was used with a chimera domain decomposition technique. The finite analytic method solved the Reynolds-Averaged Navier Stokes equation in conjunction with a near-wall second-order Reynolds stress (second-moment) closure model, and a two-layer k-ε isotropic eddy viscosity model. Comparing the second-moment and two-layer calculations with the experimental data clearly demonstrated that the angled rib turbulators and the 180 deg sharp turn of the channel produced strong non-isotropic turbulence and heat fluxes, which significantly affected the flow fields and heat transfer coefficients. The near-wall second-moment closure model provides an improved heat transfer prediction in comparison with the k-ε model.

scholarly journals Influence of fin thickness on heat transfer and flow performance of a parallel flow evaporator

2019 ◽  
Vol 23 (4) ◽  
pp. 2413-2419 ◽  
Author(s):  
Haijun Li ◽  
Enhai Liu ◽  
Guanghui Zhou ◽  
Fengye Yang ◽  
Zhiyong Su ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Comprehensive Evaluation ◽  
Reynolds Numbers ◽  
Parallel Flow ◽  
Heat Transfer Factor ◽  
Heat Transfer Capacity ◽  
Fin Thickness ◽  
The Heat Transfer Coefficient ◽  
Good Agreement

This paper studies numerically the influence of the louver?s fin thickness on heat transfer and flow performance of a parallel flow evaporator, a comprehensive evaluation and analysis of the five structures at different Reynolds numbers are systematically carried out. Comparison of the numerical results with the experimental data shows good agreement with maximal errors of 12.16% and 5.29% for the heat transfer factor and the resistance factor, respectively. The results show that the heat transfer coefficient and the pressure drop increase with the increase of the thickness of the louver fins when the Reynolds number is a constant. The analysis of the comprehensive evaluation factor shows that the A-type fin is the best, and it can effectively strengthen the heat exchange on the air side and improve the heat transfer capacity of the system. The research results can provide reference for the structural optimization of the louver fins.

scholarly journals Anomalous intensification of separated flow and heat transfer in one and multiple row deep inclined oval trench dimples on the wall of a narrow channel and on the plate

2021 ◽  
Vol 2088 (1) ◽  
pp. 012018
Author(s):  
S A Isaev ◽  
A I Leontiev ◽  
E E Son ◽  
S V Guvernyuk ◽  
M A Zubin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Static Pressure ◽  
Separated Flow ◽  
Narrow Channel ◽  
Separation Flow ◽  
State University ◽  
Flow And Heat Transfer ◽  
Numerical Studies ◽  
Moscow State University ◽  
Good Agreement

Abstract At the stands of Research Institute of Mechanics at the Moscow State University, we experimentally confirmed the mechanism of anomalous intensification of the separation flow and heat exchange in inclined oval-trench dimples (OTD) on the plate, which was discovered during numerical studies. The measured static pressure differences in single OTD at Re=6.7×104 are in good agreement with the numerical forecasts within the framework of the RANS approach at Re=104.

Effect of Corrugation on the Performance of Porous Baffles Used as Weather Shelters on Oil and Gas Platforms

2014 ◽  
Author(s):  
Geanette Polanco ◽  
Mohamad Y. Mustafa ◽  
Yizhong Xu
Keyword(s):  
Experimental Data ◽  
Oil And Gas ◽  
Flow Characteristics ◽  
Local Pressure ◽  
Numerical Studies ◽  
Dimensional Simulation ◽  
Stream Lines ◽  
Offshore Oil ◽  
Sheltered Area ◽  
Good Agreement

Porous baffles are usually used for weather protection on onshore and offshore oil installations in order to provide a sheltered area for personnel to operate. Corrugated fences are more favourable than flat fences in large installations, due to their increased stiffness; however, the performance of those fences is expected to differ from flat fences due to changes in porosity and flow structure. In this work, the experimental and numerical studies of the influence of corrugated fence on the flow characteristics are presented. The tri-dimensional effect imposed by the angle of corrugation and the depth of the fence influences the windward and leeward flow characteristics with respect to the fence. Velocity coefficient is used as one important parameter for measuring the performance of porous fences. It was found that, under similar conditions, the total obstruction produced by the corrugated fence varies significantly from that of the flat fence. Hence, velocity reduction for a corrugated fence system is expected to be smaller. A complete description of the physics of the fluid mechanics around the fence is given. Furthermore, the behaviour of the stream lines close to the fences in both cases; corrugated and non-corrugated, were studied using CFD techniques. Through observation of local pressure distribution, it was possible to reveal how velocity variations were concentrated around the inclined sections of the corrugated fence. In performing the numerical simulations, a two dimensional approach was initially implemented to capture the flow behaviour in the vicinity of the inclined sections. Subsequently, a tri-dimensional simulation on a section of the fence was undertaken and compared with experimental data. The results of the simulations were in good agreement with experimental data obtained from wind tunnel tests.

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