scholarly journals Skeletal heat conductivity of porous metal fiber materials

2021 ◽  
Vol 27 (2) ◽  
pp. 70-77
Author(s):  
A.G. Kostornov ◽  
◽  
A.A. Shapoval ◽  
I.V. Shapoval ◽  
◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Porous Materials ◽  
Porous Metal ◽  
Heat Pipes ◽  
Metal Fiber ◽  
Two Phase ◽  
Research Results ◽  
Fiber Materials ◽  
Two Phase Heat Transfer

The influence of a number of physical characteristics and parameters of metallic fiber materials on their thermal conductivity is studied in this work. Such porous materials are intended, among other things, for their effective use in two-phase heat transfer devices (heat pipes). The use of heat pipes in aircraft and space vehicles provides a number of thermophysical advantages. In particular, heat pipes significantly expand the possibilities of air cooling of heat-loaded technical devices. The thermal conductivity of capillary-porous materials-structures, which are important elements of heat pipes, significantly affects the intensity of two-phase heat transfer inside heat pipes. Frame thermal conductivity is equivalent to the thermal conductivity of materials that are conditionally continuous medium. Studies of the influence of structural characteristics of porous materials, such as porosity and parameters (dimensions) of discrete particles-fibers (fractions of the studied materials), were performed using special experimental equipment created at the I.M. Frantsevich Institute for Problems of Materials Science of the National Academy of Sciences of Ukraine (Kyiv). Porous metal structures (coatings) made of copper, nickel, and steel fibers (MPM) were investigated under conditions similar to those for space heat pipes. The porosity values ​​of the prototypes of materials were in the range of 40 to 93%. The research results showed that the following physical characteristics of capillary structures, such as values ​​of thermal conductivity of metallic materials (fiber fractions), the porosity of capillary-porous metal materials (structures), significantly affect the value of thermal conductivity of porous materials. The dimensions of discrete particles-fibers also affect in a certain way the value of the MBM thermal conductivity but to a lesser degree. The results obtained in this work are summarized in the form of empirical dependencies – formulas, providing engineering calculations of the thermal conductivity values ​​of metal fiber materials. The research results are intended for practical application in aviation and spacecraft apparatus engineering. In particular, the presented results are necessary for the development and creation of effective heat pipes with metal fiber capillary structures.

scholarly journals Recent Advances in Heat Transfer Enhancements: A Review Report

2010 ◽  
Vol 2010 ◽  
pp. 1-28 ◽  
Author(s):  
M. Siddique ◽  
A.-R. A. Khaled ◽  
N. I. Abdulhafiz ◽  
A. Y. Boukhary
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Porous Media ◽  
High Thermal Conductivity ◽  
Vortex Generators ◽  
Two Phase ◽  
Enhancement Method ◽  
Enhancing Heat Transfer ◽  
Porous Fins ◽  
Two Phase Heat Transfer

Different heat transfer enhancers are reviewed. They are (a) fins and microfins, (b) porous media, (c) large particles suspensions, (d) nanofluids, (e) phase-change devices, (f) flexible seals, (g) flexible complex seals, (h) vortex generators, (i) protrusions, and (j) ultra high thermal conductivity composite materials. Most of heat transfer augmentation methods presented in the literature that assists fins and microfins in enhancing heat transfer are reviewed. Among these are using joint-fins, fin roots, fin networks, biconvections, permeable fins, porous fins, capsulated liquid metal fins, and helical microfins. It is found that not much agreement exists between works of the different authors regarding single phase heat transfer augmented with microfins. However, too many works having sufficient agreements have been done in the case of two phase heat transfer augmented with microfins. With respect to nanofluids, there are still many conflicts among the published works about both heat transfer enhancement levels and the corresponding mechanisms of augmentations. The reasons beyond these conflicts are reviewed. In addition, this paper describes flow and heat transfer in porous media as a well-modeled passive enhancement method. It is found that there are very few works which dealt with heat transfer enhancements using systems supported with flexible/flexible-complex seals. Eventually, many recent works related to passive augmentations of heat transfer using vortex generators, protrusions, and ultra high thermal conductivity composite material are reviewed. Finally, theoretical enhancement factors along with many heat transfer correlations are presented in this paper for each enhancer.

High Heat Flux Absorption Utilizing Porous Materials With Two-Phase Heat Transfer

1997 ◽  
Vol 119 (3) ◽  
pp. 171-179 ◽  
Author(s):  
J. T. Dickey ◽  
G. P. Peterson
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Porous Materials ◽  
Metal Flow ◽  
High Heat ◽  
High Heat Flux ◽  
Two Phase ◽  
Macro Scale ◽  
Flow Through ◽  
Two Phase Heat Transfer

By combining two-phase heat transfer with forced convective flow through a porous material, a new heat transfer scheme emerges with the ability to absorb high heat fluxes without the corresponding temperature increase encountered in single-phase systems. In general, flow-through sintered metals are characterized by high thermal conductivity due to the metallic media, and a fluid flow which on the macro scale can be described as slug flow in nature. These same characteristics are exhibited by liquid metal flow cooling systems. To predict the heat transfer attributes of this two-phase flow process, a semi-analytical model was developed using the conservation equations of mass, momentum, and energy along with the apparent physical properties of the composite material. The results indicate that when a heat flux is applied to one side of the bounding surface and adiabatic conditions exist on the remaining sides, the surface temperature asymptotically approaches the same value regardless of the mass flow rate. In addition to the analytical results, definitions for the convection coefficient and Nusselt number for flow-through porous materials with phase change are presented.

Laser flash thermal conductivity studies of porous metal fiber materials

1988 ◽  
Vol 63 (6) ◽  
pp. 1971-1976 ◽  
Author(s):  
M. Golombok ◽  
L. C. Shirvill
Keyword(s):  
Thermal Conductivity ◽  
Porous Metal ◽  
Laser Flash ◽  
Metal Fiber ◽  
Fiber Materials

MICROSCALE TWO PHASE HEAT TRANSFER ENHANCEMENT IN POROUS STRUCTURES

Equipment ◽  
2006 ◽  
Author(s):  
Leonid L. Vasiliev ◽  
A. Zhuravlyov ◽  
A. Shapovalov ◽  
L. L. Vasiliev, Jr
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Porous Structures ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Two Phase Heat Transfer

ENHANCEMENT OF DESALINATION PROCESS INVOLVING TWO PHASE HEAT TRANSFER: AN EXPERIMENTAL STUDY

2018 ◽  
Author(s):  
Rajiva Lochan Mohanty ◽  
Abhilas Swain ◽  
Mihir Kumar Das
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Two Phase ◽  
Two Phase Heat Transfer

Reduced Pressure Boiling Heat Transfer in Rectangular Microchannels With Interconnected Reentrant Cavities

2005 ◽  
Vol 127 (10) ◽  
pp. 1106-1114 ◽  
Author(s):  
Ali Koşar ◽  
Chih-Jung Kuo ◽  
Yoav Peles
Keyword(s):  
Heat Transfer ◽  
Heat Fluxes ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Convective Boiling ◽  
Reduced Pressure ◽  
Exit Pressure ◽  
Mass Fluxes ◽  
Mechanism Transition ◽  
Two Phase Heat Transfer

Boiling flow of deionized water through 227μm hydraulic diameter microchannels with 7.5μm wide interconnected reentrant cavities at 47 kPa exit pressure has been investigated. Average two-phase heat transfer coefficients have been obtained over effective heat fluxes ranging from 28 to 445W∕cm2 and mass fluxes from 41 to 302kg∕m2s. A map is developed that divides the data into two regions where the heat transfer mechanisms are nucleation or convective boiling dominant. The map is compared to similar atmospheric exit pressure data developed in a previous study. A boiling mechanism transition criterion based on the Reynolds number and the Kandlikar k1 number is proposed.

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