Theoretical Analysis on Heat Transfer Characteristics of Metal Rubber

2011 ◽  
Vol 183-185 ◽  
pp. 1696-1700
Author(s):  
Bin Zhu ◽  
Jie Hong ◽  
Yan Hong Ma
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Conductivity Coefficient ◽  
Heat Insulation ◽  
Engineering Application ◽  
Porous Metal ◽  
Transfer Model ◽  
Fourier Law ◽  
Theoretical Support ◽  
Metal Rubber

Based on the basic components of the porous Metal Rubber (MR) materials, all kinds of heat transfer modes were analyzed. Wire helix was considered as the micro-element of Metal Rubber by analyzing the characteristics of processing components of Metal Rubber. According to the acoustoelectric analogy method, the heat transfer model of MR was established on the basis of arrangement of wire helix and Fourier Law. The formula of thermal conductivity coefficient was derived. And the LFA 427 instrument was used to obtain thermal conductivity characteristics of MR experimentally. The results showed that the model had certain application. This model was valuable for the analysis of the thermal properties and the design of Metal Rubber. It provided theoretical support for the further engineering application of Metal Rubber in the field of heat insulation.

Theoretical Research of Thermal Conductivity Model of Metal Rubber Based on the Wire Helix

2012 ◽  
Author(s):  
Yan-Hong Ma ◽  
Hong-Wei Lu ◽  
Zheng-Dong Ma ◽  
Bin Zhu ◽  
Jie Hong
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Conductivity Coefficient ◽  
Heat Transfer Process ◽  
Theoretical Research ◽  
Fourier Law ◽  
Conductivity Model ◽  
Theoretical Support ◽  
Thermal Conductivity Model ◽  
Metal Rubber

The heat transfer process of the Metal Rubber is in combination with the modes of heat transfer and the characteristics of Metal Rubber micro-element structure. Under certain conditions, the heat transfer questions can be simplified to the thermal conductivity questions. Based on the Fourier law, the characteristics of the thermal conductivity of Metal Rubber micro-element structure were analyzed by using thermoelectric analogy method. Combined with the equivalent coefficient law of the thermal conductivity, the thermal conductivity model was established. The formula of the thermal conductivity coefficient was derived. The accuracy of the theoretical model was verified by the experimental results. This study provides strong theoretical support for the application of the heat insulation materials.

scholarly journals Conjugate heat transfer performance of stepped lid-driven cavity with Al2O3/water nanofluid under forced and mixed convection

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Naveen Janjanam ◽  
Rajesh Nimmagadda ◽  
Lazarus Godson Asirvatham ◽  
R. Harish ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mixed Convection ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Interface Temperature ◽  
Transfer Model ◽  
Transfer Performance ◽  
Driven Cavity

AbstractTwo-dimensional conjugate heat transfer performance of stepped lid-driven cavity was numerically investigated in the present study under forced and mixed convection in laminar regime. Pure water and Aluminium oxide (Al2O3)/water nanofluid with three different nanoparticle volume concentrations were considered. All the numerical simulations were performed in ANSYS FLUENT using homogeneous heat transfer model for Reynolds number, Re = 100 to 500 and Grashof number, Gr = 5000, 13,000 and 20,000. Effective thermal conductivity of the Al2O3/water nanofluid was evaluated by considering the Brownian motion of nanoparticles which results in 20.56% higher value for 3 vol.% Al2O3/water nanofluid in comparison with the lowest thermal conductivity value obtained in the present study. A solid region made up of silicon is present underneath the fluid region of the cavity in three geometrical configurations (forward step, backward step and no step) which results in conjugate heat transfer. For higher Re values (Re = 500), no much difference in the average Nusselt number (Nuavg) is observed between forced and mixed convection. Whereas, for Re = 100 and Gr = 20,000, Nuavg value of mixed convection is 24% higher than that of forced convection. Out of all the three configurations, at Re = 100, forward step with mixed convection results in higher heat transfer performance as the obtained interface temperature is lower than all other cases. Moreover, at Re = 500, 3 vol.% Al2O3/water nanofluid enhances the heat transfer performance by 23.63% in comparison with pure water for mixed convection with Gr = 20,000 in forward step.

STUDY ON SOLIDIFICATION OF PHASE CHANGE MATERIAL IN FRACTAL POROUS METAL FOAM

Fractals ◽  
2015 ◽  
Vol 23 (01) ◽  
pp. 1540003 ◽  
Author(s):  
CHENGBIN ZHANG ◽  
LIANGYU WU ◽  
YONGPING CHEN
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Pore Structure ◽  
Phase Change Material ◽  
Fractal Structure ◽  
Metal Foam ◽  
Porous Metal ◽  
Solid Matrix ◽  
Transfer Model ◽  
Change Material

The Sierpinski fractal is introduced to construct the porous metal foam. Based on this fractal description, an unsteady heat transfer model accompanied with solidification phase change in fractal porous metal foam embedded with phase change material (PCM) is developed and numerically analyzed. The heat transfer processes associated with solidification of PCM embedded in fractal structure is investigated and compared with that in single-pore structure. The results indicate that, for the solidification of phase change material in fractal porous metal foam, the PCM is dispersedly distributed in metal foam and the existence of porous metal matrix provides a fast heat flow channel both horizontally and vertically, which induces the enhancement of interstitial heat transfer between the solid matrix and PCM. The solidification performance of the PCM, which is represented by liquid fraction and solidification time, in fractal structure is superior to that in single-pore structure.

Study on Effective Radial Thermal Conductivity of Gas Flow through a Methanol Reactor

2015 ◽  
Vol 13 (1) ◽  
pp. 103-112 ◽  
Author(s):  
Kun Lei ◽  
Hongfang Ma ◽  
Haitao Zhang ◽  
Weiyong Ying ◽  
Dingye Fang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Temperature Distribution ◽  
Large Scale ◽  
Gas Flow ◽  
Fixed Bed ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Particle Reynolds Number

Abstract The heat conduction performance of the methanol synthesis reactor is significant for the development of large-scale methanol production. The present work has measured the temperature distribution in the fixed bed at air volumetric flow rate 2.4–7 m3 · h−1, inlet air temperature 160–200°C and heating tube temperature 210–270°C. The effective radial thermal conductivity and effective wall heat transfer coefficient were derived based on the steady-state measurements and the two-dimensional heat transfer model. A correlation was proposed based on the experimental data, which related well the Nusselt number and the effective radial thermal conductivity to the particle Reynolds number ranging from 59.2 to 175.8. The heat transfer model combined with the correlation was used to calculate the temperature profiles. A comparison with the predicated temperature and the measurements was illustrated and the results showed that the predication agreed very well with the experimental results. All the absolute values of the relative errors were less than 10%, and the model was verified by experiments. Comparing the correlations of both this work with previously published showed that there are considerable discrepancies among them due to different experimental conditions. The influence of the particle Reynolds number on the temperature distribution inside the bed was also discussed and it was shown that improving particle Reynolds number contributed to enhance heat transfer in the fixed bed.

Research on Heat Transfer Characteristics of Nano-Porous Silica Aerogel Material and its Application on Mars Surface Mission

2014 ◽  
Vol 924 ◽  
pp. 329-335 ◽  
Author(s):  
Cong Hang Li ◽  
Shi Chen Jiang ◽  
Zheng Ping Yao ◽  
Song Sheng ◽  
Xin Jian Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Silica Aerogel ◽  
Thermal Environment ◽  
Porous Silica ◽  
Heat Transfer Model ◽  
Heat Radiation ◽  
Transfer Model ◽  
Ambient Conditions ◽  
Coupled Heat Transfer

Based on the nanoporous network structure features of silica aerogel, the gas-solid coupled heat transfer model of silica aerogel is analyzed, and the calculation formulas of the gas-solid coupled, the gas thermal conductivity and the heat radiation within the aerogel are derived. The thermal conductivity of pure silica aerogel is calculated according to the derived heat transfer model and is also experimentally measured. Moreover, measurements on the thermal conductivities of silica aerogel composites with different densities at ambient conditions are performed. And finally, a novel design of silica aerogel based integrated structure and thermal insulation used for withstanding the harsh thermal environment on the Martin surface is presented.

Porous metal model for calculating slot thermal conductivity coefficient of electric machines

2017 ◽  
Vol 111 ◽  
pp. 981-988 ◽  
Author(s):  
Xiaomei Liu ◽  
Haitao Yu ◽  
Zhenchuan Shi ◽  
Lei Huang ◽  
Tao Xia ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Conductivity Coefficient ◽  
Porous Metal ◽  
Electric Machines

scholarly journals Investigation of thermal model effects on geothermal and oil reservoir well testing behavior during water and steam injection

2020 ◽  
Vol 75 ◽  
pp. 58
Author(s):  
Mahdi Abbasi ◽  
Mohammad Ahmadi ◽  
Alireza Kazemi ◽  
Mohammad Sharifi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Fluid Flow ◽  
Steam Injection ◽  
Model Parameters ◽  
Transfer Model ◽  
Diffusivity Coefficient ◽  
Reservoir Model ◽  
Type Curve ◽  
Water Steam

Global warming and reducing fossil fuel resources have increased the interest in using renewable resources such as geothermal energy. In this paper, in the first step, heat transfer equations have been presented for reservoir during water (steam) injection by considering heat loss to adjacent formations. According to radius of thermal front, the reservoir is partitioned into two regions with different fluid physical properties. The heat transfer model is coupled with a fluid flow model which is used to calculate the reservoir pressure or fluid flow rates. Then by calculating outer radius of heated region and using radial composite reservoir model, the fluid flow equations in porous media are solved. Using pressure derivative plot in regions with different thermal conductivity coefficients, a type curve plot is presented. The reservoir and adjacent formation thermal conductivity coefficients can be calculated by matching the observed pressure data on the thermal composite type curve. Additionally, the interference test in composite geothermal reservoir is discussed. In the composite reservoir model, parameters such as diffusivity coefficient, conductivity ratio and the distance to the radial discontinuity are considered. New type curves are provided to introduce the effect of diffusivity/conductivity contrast ratios on temperature behavior. Improving interpretations, and performing fast computations and fast sensitivity analysis are the benefits of the presented solutions.

Effective Thermal Conductivity of Submicron Powders: A Numerical Study

2016 ◽  
Vol 846 ◽  
pp. 500-505
Author(s):  
Wei Jing Dai ◽  
Yi Xiang Gan ◽  
Dorian Hanaor
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Granular Materials ◽  
Gas Phase ◽  
Numerical Study ◽  
Transfer Model ◽  
Size Of Particles ◽  
Contact Unit

Effective thermal conductivity is an important property of granular materials in engineering applications and industrial processes, including the blending and mixing of powders, sintering of ceramics and refractory metals, and electrochemical interactions in fuel cells and Li-ion batteries. The thermo-mechanical properties of granular materials with macroscopic particle sizes (above 1 mm) have been investigated experimentally and theoretically, but knowledge remains limited for materials consisting of micro/nanosized grains. In this work we study the effective thermal conductivity of micro/nanopowders under varying conditions of mechanical stress and gas pressure via the discrete thermal resistance method. In this proposed method, a unit cell of contact structure is regarded as one thermal resistor. Thermal transport between two contacting particles and through the gas phase (including conduction in the gas phase and heat transfer of solid-gas interfaces) are the main mechanisms. Due to the small size of particles, the gas phase is limited to a small volume and a simplified gas heat transfer model is applied considering the Knudsen number. During loading, changes in the gas volume and the contact area between particles are simulated by the finite element method. The thermal resistance of one contact unit is calculated through the combination of the heat transfer mechanisms. A simplified relationship between effective thermal conductivity and loading pressure can be obtained by integrating the contact units of the compacted powders.

Convective Heat Transfer Analysis of Open Cell Metal Foam for Solar Air Heaters

Solar Energy ◽  
2003 ◽  
Author(s):  
Nihad Dukhan ◽  
Pablo D. Quinones
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Metal Foam ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Aluminum Foams ◽  
Maximum Heat ◽  
Open Cell ◽  
Maximum Heat Transfer

A one-dimensional heat transfer model for open-cell metal foam is presented. Three aluminum foams having different areas, relative densities, ligament diameters, and number of pores per inch were analyzed. The effective thermal conductivity and the heat transfer increased with the number of pores per inch. The effective thermal conductivity of the foams can be up to four times higher than that of solid aluminum. The resulting improvement in heat transfer can be as high as 50 percent. The maximum heat transfer for the aluminum foams occurs at a pore Reynolds number of 52. The heat transfer, in addition, becomes insensitive to the flow regime for pore Reynolds numbers beyond 200.

Numerical Study on Forced Convective Heat Transfer in Porous Pin Fin Channels

2008 ◽  
Author(s):  
Jian Yang ◽  
Min Zeng ◽  
Qiuwang Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Porous Metal ◽  
Transfer Model ◽  
Transfer Performance ◽  
Pin Fin ◽  
Heat Exchanges

Pin fin heat exchanges are often used in cooling of high thermal loaded electronic components due to their excellent heat transfer performance. However, the pressure drop in such heat exchanges is usually much higher than that in others, so their overall heat transfer performance is seriously reduced. In order to reduce the pressure drop and improve the overall heat transfer performance for pin fin heat exchangers, porous metal pin arrays are used and the performance of fluid flow and heat transfer in heat exchanger unit cells are numerically studied. The Forchheimer-Brinkman extended Darcy model and two-equation heat transfer model for porous media are employed and the effects of Reynolds number (Re), permeability (K) and pin fin cross-section forms are studied in detail. The results show that, with proper selection of governing parameters, the overall heat transfer performance of porous pin fin heat exchanger is much better than that of traditional solid pin fin heat exchanger; the overall heat transfer performance of long elliptic porous pin fin heat exchanger is the best, that is, the heat transfer per unit pressure drop of such heat exchanger is the highest and the maximum value of the heat transfer over pressure drop is obtained at K = 2×10−7 m2.

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