scholarly journals Theoretical Evaluation of Microwave Ablation Applied on Muscle, Fat and Bone: A Numerical Study

2021 ◽  
Vol 11 (17) ◽  
pp. 8271 ◽  
Author(s):  
Cheng Chen ◽  
Ming-An Yu ◽  
Lin Qiu ◽  
Hong-Yu Chen ◽  
Zhen-Long Zhao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Biological Tissue ◽  
Microwave Ablation ◽  
Numerical Study ◽  
Biological Tissues ◽  
Heat Transfer Analysis ◽  
Temperature Threshold ◽  
Radiation Physics ◽  
Experimental Conditions

(1) Background: Microwave ablation (MWA) is a common tumor ablation surgery. Because of the high temperature of the ablation antenna, it is strongly destructive to surrounding vital tissues, resulting in high professional requirements for clinicians. The method used to carry out temperature observation and damage prediction in MWA is significant; (2) Methods: This work employs numerical study to explore temperature distribution of typical tissues in MWA. Firstly, clinical MWA based on isolated biological tissue is implemented. Then, the Pennes models and microwave radiation physics are established based on experimental parameters and existing related research. Initial values and boundary conditions are adjusted to better meet the real clinical materials and experimental conditions. Finally, clinical MWA data test this model. On the premise that the model is matched with clinical MWA, fat and bone are deduced for further heat transfer analysis. (3) Results: Numerical study obtains the temperature distribution of biological tissue in MWA. It observes the heat transfer law of ablation antenna in biological tissue. Additionally, combined with temperature threshold, it generates thermal damage of biological tissues and predicts the possible risks in MWA; (4) Conclusions: This work proposes a numerical study of typical biological tissues. It provides a new theoretical basis for clinically thermal ablation surgery.

Three-Dimensional Numerical Study on Freezing Phase Change Heat Transfer in Biological Tissue Embedded With Two Cryoprobes

2011 ◽  
Vol 3 (3) ◽  
Author(s):  
Fang Zhao ◽  
Zhenqian Chen
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Biological Tissue ◽  
Clinical Medicine ◽  
Numerical Study ◽  
Biological Tissues ◽  
Freezing Process ◽  
Ice Crystal ◽  
Obvious Effect ◽  
Phase Change Heat Transfer

Biological tissues undergo complex phase change heat transfer processes during cryosurgery, and a theoretical model is preferable to forecast this heat experience. A mathematical model for phase change heat transfer in cryosurgery was established. In this model, a fractal treelike branched network was used to describe the complicated geometrical frame of blood vessels. The temperature distribution and ice crystal growth process in biological tissue including normal tissue and tumor embedded with two cryoprobes were numerically simulated. The effects of cooling rate, initial temperature, and distance of two cryoprobes on freezing process of tissue were also studied. The results show that the ice crystal grows more rapidly in the initial freezing stage (<600 s) and then slows down in the following process, and the precooling of cryoprobes has no obvious effect on freezing rate of tissue. It also can be seen that the distance of 10 mm between two cryoprobes produces an optimal freezing effect for the tumor size (20 mm × 10 mm) in the present study compared with the distances of 6 mm and 14 mm. The numerical results are significant in providing technical reference for application of cryosurgery in clinical medicine.

scholarly journals Numerical Heat Transfer Analysis of an Innovative Gas Turbine Combustor: Coupled Study of Radiation and Cooling in the Upper Part of the Liner

2005 ◽  
Author(s):  
A. Andreini ◽  
A. Bacci ◽  
C. Carcasci ◽  
B. Facchini ◽  
A. Asti ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Gas Turbine ◽  
Cooling System ◽  
Numerical Study ◽  
Radiative Properties ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Cold Side ◽  
Additional Tool

A numerical study of a single can combustor for the GE10 heavy-duty gas turbine, which is being developed at GE-Energy (Oil & Gas), is performed using the STAR-CD CFD package. The topic of the present study is the analysis of the cooling system of the combustor liner’s upper part, named “cap”. The study was developed in three steps, using two different computational models. As first model, the flow field and the temperature distribution inside the chamber were determined by meshing the inner part of the liner. As second model, the impingement cooling system of the cold side of the cap was meshed to evaluate heat transfer distribution. For the reactive calculations, a closure of the BML (Bray-Moss-Libby) approach based on Kolmogorov-Petrovskii-Piskunov theorem was used. The model was implemented in the STAR-CD code using its user coding features. Then the radiative thermal load on the liner walls was evaluated by means of the STAR-CD-native Discrete Transfer model. The selection of the radiative properties of the flame was performed using a correlation procedure involving the total emissivity of the gas, the mean beam length and the gas temperature. The estimated heat flux on the cap was finally used as boundary condition for the calculation of the cooling system, consisting of 68 staggered impingement jet lines on the cold side of the cap. The resulting temperature distribution shows a good agreement with the experimental values measured by thermocouples. The results confirm the validity of the implemented procedure, and point out the importance of a full CFD computation as an additional tool to support classic correlation design procedures.

Investigation Into Thermal Stress Characteristics of Pipe-in-Pipe Under High Temperature Condition

2018 ◽  
Author(s):  
Si-Hwa Jeong ◽  
Min-Gu Won ◽  
Nam-Su Huh ◽  
Yun-Jae Kim ◽  
Young-Jin Oh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
High Temperature ◽  
Temperature Distribution ◽  
Heat Transfer Analysis ◽  
Piping System ◽  
Curved Pipe ◽  
High Temperature Condition ◽  
Single Pipe ◽  
Radiation Conditions

In this paper, the thermal stress characteristics of the pipe-in-pipe (PIP) system under high temperature condition are analyzed. The PIP is a type of pipe applied in sodium-cooled faster reactor (SFR) and has a different geometry from a single pipe. In particular, under the high temperature condition of the SFR, the high thermal stress is generated due to the temperature gradient occurring between the inner pipe and outer pipe. To investigate the thermal stress characteristics, three cases are considered according to geometry of the support. The fully constrained support and intermediate support are considered for case 1 and 2, respectively. For case 3, both supports are applied to the actual curved pipe. The finite element (FE) analyses are performed in two steps for each case. Firstly, the heat transfer analysis is carried out considering the thermal conduction, convection and radiation conditions. From the heat transfer analysis, the temperature distribution results in the piping system are obtained. Secondly, the structural analysis is performed considering the temperature distribution results and boundary conditions. Finally, the effects of the geometric characteristics on the thermal stress in the PIP system are analyzed.

scholarly journals A Numerical Study of MHD and Heat Transfer Analysis in a non-Newtonian Eyring-Powell Fluid from an Isothermal Sphere with Thermal Slip

2017 ◽  
Vol 10 (17) ◽  
pp. 1-5
Author(s):  
K. Madhavi ◽  
N. Nagendra ◽  
V. Ramachandra Prasad ◽  
A. Subba Rao ◽  
G. S. S. Raju ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Heat Transfer Analysis ◽  
Thermal Slip

scholarly journals Numerical Simulation of Secondary Flow in Gas Turbine Disc Cavities, Including Conjugate Heat Transfer

1996 ◽  
Author(s):  
Y.-H. Ho ◽  
M. M. Athavale ◽  
J. M. Forry ◽  
R. C. Hendricks ◽  
B. M. Steinetz
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Conjugate Heat Transfer ◽  
Gas Flow ◽  
Numerical Study ◽  
Labyrinth Seal ◽  
Temperature Fields ◽  
Heat Transfer Analysis ◽  
Flow Rates ◽  
Turbine Disc

A numerical study of the flow and heat transfer in secondary flow elements of the entire inner portion of the turbine section of the Allison T-56/501D engine is presented. The flow simulation included the interstage cavities, rim seals and associated main path flows, while the energy equation also included the solid parts of the turbine disc, rotor supports, and stator supports. Solutions of the energy equations in these problems usually face the difficulty in specifications of wall thermal boundary conditions. By solving the entire turbine section this difficulty is thus removed, and realistic thermal conditions are realized on all internal walls. The simulation was performed using SCISEAL, an advanced 2D/3D CFD code for predictions of fluid flows and forces in turbomachinery seals and secondary flow elements. The mass flow rates and gas temperatures at various seal locations were compared with the design data from Allison. Computed gas flow rates and temperatures in the rim and labyrinth seal show a fair 10 good comparison with the design calculations. The conjugate heat transfer analysis indicates temperature gradients in the stationary intercavity walls, as well as the rotating turbine discs. The thermal strains in the stationary wall may lead to altered interstage labyrinth seal clearances and affect the disc cavity flows. The temperature, fields in the turbine discs also may lead to distortions that can alter the rim seal clearances. Such details of the flow and temperature fields are important in designs of the turbine sections to account for possible thermal distortions and their effects on the performance. The simulation shows that the present day CFD codes can provide the means to understand the complex flow field and thereby aid the design process.

scholarly journals Numerical Study of the Effect of the Location of Baffles on the Flow and Heat Transfer of A Newtonian Fluid in A Ventilated Enclosure

2021 ◽  
Vol 321 ◽  
pp. 04007
Author(s):  
Abdelkader Boutra ◽  
Seddik Kherroubi ◽  
Abderrahmane Bourada ◽  
Youb Khaled Benkahla ◽  
Nabila Labsi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Industrial Applications ◽  
Optimal Choice ◽  
Heat Transfer Analysis ◽  
Heat Conducting ◽  
Algebraic Equations ◽  
Pressure Line ◽  
Flow And Heat Transfer ◽  
Simpler Algorithm

Flow and heat transfer analysis in ventilated cavities is one of the most widely studied problems in thermo-fluids area. Two-dimensional mixed convection in a ventilated rectangular cavity with baffles is studied numerically and the fluid considered in this study is hot air (Pr = 0.71). The horizontal walls are maintained at a constant temperature, higher than that imposed on the vertical ones. Two very thin heat-conducting baffles are inserted inside the enclosure, on its horizontal walls, to control the flow of convective fluid. The governing equations are discretized using the finite volume method and the SIMPLER algorithm to treat the coupling velocity–pressure. Line by line method is used to solve iteratively the algebraic equations. The effect of the Richardson number Ri (0.01- 100) and the location of the baffles within the cavity on the isothermal lines, streamlines distributions and the average Nusselt number (Nu) has been investigated. The result shows that the location opposite the baffles, close to the fluid outlet, is the optimal choice to be considered for industrial applications.

Effect of Wall Conduction on Combined Free and Forced Laminar Convection in Horizontal Rectangular Channels

1987 ◽  
Vol 109 (4) ◽  
pp. 936-942 ◽  
Author(s):  
G. J. Hwang ◽  
F. C. Chou
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Temperature Distribution ◽  
Finite Difference ◽  
Aspect Ratio ◽  
Finite Difference Method ◽  
Numerical Study ◽  
Fully Developed Flow ◽  
Rectangular Channels ◽  
Laminar Convection

This paper presents a numerical study of the effect of peripheral wall conduction on combined free and forced laminar convection in hydrodynamically and thermally fully developed flow in horizontal rectangular channels with uniform heat input axially, In addition to the Prandtl number, the Grashof number Gr+, and the aspect ratio γ, a parameter Kp indicating the significance of wall conduction plays an important role in heat transfer. A finite-difference method utilizing a power-law scheme is employed to solve the system of governing partial differential equations coupled with the equation for wall conduction. The numerical solution covers the parameters: Pr = 7.2 and 0.73, γ = 0.5, 1, and 2, Kp = 10−4–104, and Gr+ = 0–1.37×105. The flow patterns and isotherms, the wall temperature distribution, the friction factor, and the Nusselt number are presented. The results show a significant effect of the conduction parameter Kp.

Analysis to Reduce Thermal Stress in Oxide Single Crystal During Czochralski Growth

2004 ◽  
Author(s):  
Shigeki Hirasawa ◽  
Hiroyuki Ishibashi ◽  
Kazuhisa Kurashige ◽  
Akihiro Gunji
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Temperature Distribution ◽  
Thermal Radiation ◽  
Single Crystal ◽  
Radiation Heat Transfer ◽  
Heat Transfer Analysis ◽  
Czochralski Growth ◽  
Radiation Heat ◽  
Radial Temperature

Temperature distributions and thermal stress distributions in a semi-transparent GSO crystal during Czochralski (CZ) single crystal growth were numerically investigated by thermal radiation heat transfer analysis and anisotropy stress analysis. As GSO has special optical properties, such as semi-transparency at a wavelength shorter than 4.5 μm, thermal radiation heat transfer was calculated by the Monte Carlo method. These calculations showed that thermal stress is caused by the radial temperature distribution on the outside of the upper part of the crystal. To reduce this temperature distribution, the following three manufacturing conditions were found to be effective: use a sharp taper angle of the crystal, install a lid to the top of the insulator, and install a ring around the tapered part of the crystal.

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