Numerical Simulation on Heat Transfer in a Novel Combined Therapy of Nano-Cryosurgery and RF Hyperthermia

2012 ◽  
Author(s):  
Zhong-Shan Deng ◽  
Jing Liu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Magnetic Nanoparticles ◽  
Treatment Efficacy ◽  
Treatment Process ◽  
Combined Therapy ◽  
Target Tissue ◽  
Tumor Treatment ◽  
Numerical Investigations

In this study, a novel combined therapy of nano-cryosurgery and RF induced nano-hyperthermia was proposed, with the purpose of improving tumor treatment efficacy. To better understand the mechanisms of enhancement on freezing and heating by introducing magnetic nanoparticles with high thermal conductivity during the combined therapy of nano-cryosurgery and RF hyperthermia, a series of numerical investigations were performed. The results indicate that the combined therapy of nano-cryosurgery and RF hyperthermia can serve as an applicable way to flexibly control the size and shape of lethal freezing/heating areas, which will help selectively ablate the target tissue and then optimize the thermal treatment process for tumor.

scholarly journals The numerical simulation of enhanced heat transfer on a Linear Fresnel molten salt-type receiver tube filled with porous media

2019 ◽  
Vol 118 ◽  
pp. 01041
Author(s):  
Chenggang Yang ◽  
Yuning Zhang ◽  
Fenghe Yan ◽  
Wenguang Zhang ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Porous Media ◽  
Molten Salt ◽  
Temperature Difference ◽  
Wall Temperature ◽  
Three Dimensional ◽  
Heat Transfer Fluid ◽  
Filling Rate

In this paper, three-dimensional numerical simulation was taken on a Linear Fresnel solar receiver tube using molten salt as heat transfer fluid (HTF), in which the porous media was filled to enhance the heat transfer efficiency. The simulation was to analyze the influence of the different conditions (filling rate, porosity and thermal conductivity) on heat transfer effect and wall temperature difference. The results revealed that the Nu (Nusselt number) increased firstly and then decreased with the increasing filling rate in both center filling and annular filling types. The optimal thermal performance were obtained when filling rate were 0.8 and 0.2 in center filling and annular filling, respectively. The Nu were about 1.7 and 1.5 times as the clear receiver. The circumferential temperature difference decreased firstly and then increased with filling rate increasing in both center filling and annular filling types. The lowest circumferential temperature differences were achieved at the filling rate 0.8 and 0.4 in center filling and annular filling types, and temperature difference decreased 15.88°C and 22°C compared with clear receiver, respectively. The Nu and PEC both decreased with porosity increasing. However, the thermal conductivity of porous media had little influence to the Nu and circumferential wall temperature.

Parametric Analysis of Floor Cooling

2016 ◽  
Vol 861 ◽  
pp. 401-408
Author(s):  
Lucie Horká ◽  
Jan Weyr
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Parametric Analysis ◽  
Cooling Water ◽  
Total Heat ◽  
Design Parameters ◽  
Total Heat Transfer ◽  
2D Numerical Simulation ◽  
Cooling Pipes

This study is aimed at parametric analysis of floor cooling. Impact of several design parameters such as air temperature, temperature of cooling water, distance of cooling pipes, thickness and thermal conductivity of top layer on total heat transfer of cooling floor is studied. The issue is solved by steady-state 2D numerical simulation of heat transfer to the floor construction. These parametric simulations are performed in software CalA. Impact of variable input parameters on total heat transfer is observed. Results of parametric analysis are displayed in a nomogram. This nomogram is useful for faster designing of floor cooling.

scholarly journals A predictive model of thermal conductivity of plain woven fabrics

2017 ◽  
Vol 21 (4) ◽  
pp. 1627-1632 ◽  
Author(s):  
Jia-Jia Wu ◽  
Hong Tang ◽  
Yu-Xuan Wu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Heat Flux ◽  
Thermal Comfort ◽  
Cell Model ◽  
Woven Fabrics ◽  
Woven Fabric ◽  
Unit Cell Model ◽  
Fabric Structure

This paper proposes an effective method to predict the thermal conductivity of plain woven blended fabric to optimize woven fabric structure, and to evaluate thermal comfort. The unit cell model of fabric is established for numerical simulation of heat transfer through thickness. The thermal conductivity of blended yarns is calculated by a series model. The temperature and heat flux distributions are verified experimentally.

Preparation and Numerical Simulation of Heat Transfer Performance for Methyl Palmitate /Expanded Graphite Phase Change Composite

2020 ◽  
Vol 834 ◽  
pp. 132-138
Author(s):  
Bi Chuan Chi ◽  
Yan Yao ◽  
Su Ping Cui
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Energy Storage ◽  
Phase Change ◽  
Methyl Palmitate ◽  
Phase Change Materials ◽  
Heat Transfer Performance ◽  
Expanded Graphite ◽  
Transfer Performance

Methyl palmitate (MP) is a promising phase change energy storage material. It features high latent heat, suitable phase change temperature, low degree of supercooling and so on. However, like other organic phase change materials, the common problem of lower thermal conductivity makes it unable to perform better in energy storage. Expanded graphite (EG) has been proven to be high-efficiency for enhancing the thermal conductivity of organic phase change materials. MP/EG phase change composite was prepared and characterized in this research, and the heat transfer performance was numerical simulated by finite element analysis software ABAQUS. Results show that MP can be absorbed into the layered pores of EG, and the stable absorption ratio is 77%. Numerical simulation results reveal that EG can significantly enhance the heat transfer performance of MP. Moreover, EG can decrease the system temperature gradient during phase change process that makes the heat transfer and temperature distribution more uniform.

scholarly journals Mathematical modeling of heat transfer in a closed two- phase thermosyphon

2019 ◽  
Vol 21 (3) ◽  
pp. 3-13
Author(s):  
V. I. Maksimov ◽  
A. Е. Nurpeiis
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Heat Flow ◽  
Problem Solution ◽  
Two Phase ◽  
Evaporation Zone ◽  
Characteristic Temperatures ◽  
Simulation Results

We suggested a new approach for describing heat transfer in thermosyphons and determining the characteristic temperatures. The processes of thermogravitation convection in the coolant layer at the lower cap, phase transitions in the evaporation zone, heat transfer as a result of conduction in the lower cap are described at the problem statement. The main assumption, which was used during the problem formulation, is that the characteristic times of steam motion through the thermosyphon channel are much less than the characteristic times of thermal conductivity and free convection in the coolant layer at the lower cap of the thermosyphon. For this reason, the processes of steam motion in the thermosyphon channel, the condensate film on the upper cap and the vertical walls were not considered. The problem solution domain is a thermosyphon through which heat is removed from the energy-saturated equipment. The ranges of heat flow changes were chosen based on experimental data. The geometric parameters of thermosyphon and the fill factors were chosen the same as in the experiments (height is 161 mm, diameter is 42 mm, wall thickness is 1.5 mm, ε=4-16%) for subsequent comparison of numerical simulation results and experimental data. In the numerical analysis it was assumed that the thermophysical properties of thermosyphon and coolant caps do not depend on temperature; laminar flow regime was considered. The dimensionless equations of vortex, Poisson and energy transfer for the liquid coolant under natural convection and the equations of thermal conductivity for the lower cap wall are solved by the method of finite differences. Numerical simulation results showed the relationship between the characteristic temperatures and the heat flow supplied to the bottom cap of thermosyphon. The results of the theoretical analysis are in satisfactory agreement with the known experimental data. 

scholarly journals Влияние химической модификации поверхности углеродных нанотрубок на их теплопроводность

2019 ◽  
Vol 61 (2) ◽  
pp. 409
Author(s):  
А.В. Савин ◽  
О.И. Савина
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Outer Side ◽  
Partial Hydrogenation ◽  
Single Walled Carbon Nanotube ◽  
Proportionality Coefficient ◽  
Reduction Coefficient ◽  
Partial Chemical ◽  
Modification Of The Surface

AbstractAn effect of partial chemical modification of the surface of a single-walled carbon nanotube on its thermal conductivity is studied. Numerical simulation of heat transfer showed that partial hydrogenation (fluorination) of a nanotube (addition of hydrogen and fluorine atoms from its outer side) can lead to more than a tenfold decrease in thermal conductivity. When the length of the nanotube increases, its thermal conductivity increases in proportion to the logarithm of the length, whereas the proportionality coefficient decreases with an increase in density of hydrogen or fluorine atoms attached. A thermal conductivity reduction coefficient does not depend on the length of the nanotube, but depends on temperature (the lower the temperature, the stronger the decrease) and density of the attached atoms p . When p < 0.25, an increase in density monotonically decreases the thermal conductivity. A decrease is maximum, when density p is 0.25. If only one half of the nanotube is hydrogenated, this half has a lower thermal conductivity. Such a nanotube becomes anisotropic and can be used as a heat transfer rectifier with no more than two percent rectification efficiency.

Numerical Simulation of Conjugate Heat Transfer From Multiple Electronic Module Packages Cooled by Air

2003 ◽  
Author(s):  
Hideo Yoshino ◽  
Motoo Fujii ◽  
Xing Zhang ◽  
Masud Behnia
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Conjugate Heat Transfer ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Heat Transfer Area ◽  
Printed Circuit ◽  
Effective Heat ◽  
Parallel Arrangement

This paper reports on the numerical simulation of conjugate heat transfer from multiple electronic module packages (45 × 45 × 2.4 mm) on a printed circuit board placed in a duct. The dimensions of the modules are the same as a single module package previously studied. In the series arrangement, two module packages are installed on the center of the printed circuit board along the airflow direction. In the parallel arrangement, two and/or four module packages are installed normal to the airflow direction. In the numerical simulations, the interval between the module packages was varied and three values were considered (45, 22.5 and 9 mm). The variation of the printed circuit board thermal conductivity was also considered and 0.3, 3 and 20 W/m/K were used with the mean velocity in the duct also at three different values (0.33, 0.67 and 1 m/s). In order to derive a non-dimensional correlation from the numerical results, the concept of the effective heat transfer area previously used for a single module package was used for the multiple module packages. For the series arrangement, the effects of the interval on the effective heat transfer area are relatively low, and the numerical results can be summarized with the same correlation obtained from the single module package. On the other hand, the effective heat transfer area for the parallel arrangement is strongly affected by the parallel interval and the thermal conductivity of printed circuit board. When the interval increases, the temperature of the module packages greatly reduces as the thermal conductivity of the printed circuit board increases.

Numerical Simulation for Conjugated Heat Transfer in Concentric Tube Recuperator with Longitudinal Fins

2013 ◽  
Vol 753-755 ◽  
pp. 948-954 ◽  
Author(s):  
Ming Hui Liu ◽  
Cui Zhen Zhang ◽  
Mo Yang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Nusselt Number ◽  
Fluid Flow ◽  
Friction Factor ◽  
Transfer Problem ◽  
Longitudinal Length ◽  
Conjugated Heat Transfer ◽  
Simulation Results

In this paper, a conjugated heat transfer problem of conduction and convection in the concentric tubes with longitudinal fins was studied by means of numerical simulation. 3D temperature and fluid flow fields were simulated for three-split concentric tube recuperator with longitudinal fins for laminar fluid flow. The numerical simulation results show that the ratio of , which is the function of the angle of fins and axis, and solid thermal conductivity, decreases quickly as longitudinal length increases. If the conduit is long enough, the ratio of can be neglected. The ratio of Nusselt number and the ratio of friction factor increase as the angle of fins and axis increases, and the ratio of Nusselt number increases more quickly than that of the friction factor for the same angle.

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