scholarly journals Analysing the Contact Conduction Influence on the Heat Transfer Intensity in the Rectangular Steel Bars Bundle

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5655
Author(s):  
Cezary Kolmasiak ◽  
Vazgen Bagdasaryan ◽  
Tomasz Wyleciał ◽  
Marek Gała
Keyword(s):  
Heat Transfer ◽  
Heat Treatment ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Heating Time ◽  
Point Of View ◽  
Temperature Function ◽  
Electrical Analogy ◽  
Steel Bars

Bundles of steel bars, besides metal foams, are an example of cellular solids. Such bundles constitute a charge during the heat treatment of bars. The paper presents a mathematical model of transient heat transfer in a bundle of rectangular steel bars based on the energy balance method. The key element of this model is the procedure of determining the effective thermal conductivity using the electrical analogy. Different mechanisms of heat transfer occurring within the analysed medium (conduction in steel and contact conduction) are assigned corresponding thermal resistances. The discussed procedure involves expressing these resistances with the use of arithmetic relationships describing their changes in the temperature function. Thermal contact resistance has been described with the use of the relationships determined experimentally. As a result of the performed calculations, the influence of contact conduction between the adjacent bars and bundle arrangement on its heating time was established. The results of the calculations show that the heating time of bundles can be lowered by 5–40% as a result of a decrease in the thermal contact resistance. This effect depends on the bar size and bundle arrangement. From the practical point of view, the analysed problem is connected with the optimization of the heat treatment processes of steel bars.

scholarly journals Multifunctional Cantilevers as Working Elements in Solid-State Cooling Devices

Actuators ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 58
Author(s):  
Andraž Bradeško ◽  
Lovro Fulanović ◽  
Marko Vrabelj ◽  
Aleksander Matavž ◽  
Mojca Otoničar ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Ethylene Glycol ◽  
Contact Resistance ◽  
High Efficiency ◽  
Thermal Contact ◽  
Point Of View ◽  
Practical Implementation ◽  
Cooling Devices ◽  
Cascade Structure ◽  
Lead Magnesium

Despite the challenges of practical implementation, electrocaloric (EC) cooling remains a promising technology because of its good scalability and high efficiency. Here, we investigate the feasibility of an EC cooling device that couples the EC and electromechanical (EM) responses of a highly functionally, efficient, lead magnesium niobate ceramic material. We fabricated multifunctional cantilevers from this material and characterized their electrical, EM and EC properties. Two active cantilevers were stacked in a cascade structure, forming a proof-of-concept device, which was then analyzed in detail. The cooling effect was lower than the EC effect of the material itself, mainly due to the poor solid-to-solid heat transfer. However, we show that the use of ethylene glycol in the thermal contact area can significantly reduce the contact resistance, thereby improving the heat transfer. Although this solution is most likely impractical from the design point of view, the results clearly show that in this and similar cooling devices, a non-destructive, surface-modification method, with the same effectiveness as that of ethylene glycol, will have to be developed to reduce the thermal contact resistance. We hope this study will motivate the further development of multifunctional cooling devices.

scholarly journals Study of an inclined interface of contact using lattice Boltzmann method

2019 ◽  
Vol 23 (3 Part B) ◽  
pp. 1837-1846
Author(s):  
Mhamdi El ◽  
Elalami Semma
Keyword(s):  
Heat Transfer ◽  
Contact Resistance ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Thermal Contact Resistance ◽  
Transfer Problem ◽  
Thermal Contact ◽  
Image Model ◽  
Steady Regime ◽  
Boltzmann Method

The lattice Boltzmann method and the particle image model are adopted to study a heat transfer problem with thermal contact resistance. In this paper, a new study involving an inclined interface of contact between two media is introduced in order to evaluate a 2-D heat transfer in the steady regime. A case of study and numerical results are provided to support this configuration. The obtained results show the effect of the thermal contact resistance on the heat transfer, as well as the temperature distribution on the two contacting media.

The problem of thermal contact resistance during heat transfer to liquid metals

Atomic Energy ◽  
1962 ◽  
Vol 11 (3) ◽  
pp. 910-913
Author(s):  
O. P. Astakhov ◽  
V. I. Petrov ◽  
O. S. Fedynskii
Keyword(s):  
Heat Transfer ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Liquid Metals ◽  
Thermal Contact

Investigation of Pressure Dependent Thermal Contact Resistance between Silver Metallized SiC Chip and DBC Substrate

2015 ◽  
Vol 821-823 ◽  
pp. 452-455 ◽  
Author(s):  
Zsolt Toth Pal ◽  
Ya Fan Zhang ◽  
Ilja Belov ◽  
Hans Peter Nee ◽  
Mietek Bakowski
Keyword(s):  
Heat Transfer ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Cfd Simulation ◽  
Thermal Contact ◽  
Cfd Model ◽  
Transfer Experiment ◽  
Transfer Path ◽  
Computational Fluid Dynamics Cfd ◽  
Pressure Independent

– Thermal contact resistances between a silver metallized SiC chip and a direct bonded copper (DBC) substrate have been measured in a heat transfer experiment. A novel experimental method to separate thermal contact resistances in multilayer heat transfer path has been demonstrated. The experimental results have been compared with analytical calculations and also with 3D computational fluid dynamics (CFD) simulation results. A simplified CFD model of the experimental setup has been validated. The results show significant pressure dependence of the thermal contact resistance but also a pressure independent part.

Measuring the Thermal Contact Resistance Between Cu Foams and Substrates for On-Chip Cooling Applications in Data Centers

2021 ◽  
Author(s):  
Lucas Arrivo ◽  
Steven Schon ◽  
Aaron P. Wemhoff
Keyword(s):  
Heat Transfer ◽  
Contact Resistance ◽  
Data Centers ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Metal Foams ◽  
Heat Transfer Area ◽  
Chip Cooling ◽  
Cold Plates ◽  
On Chip

Abstract Data centers housing high performance computing equipment have large and growing rack densities, which pushes the limits of traditional air cooling technologies because of limited heat transfer coefficients. Therefore, on-chip cooling using so-called cold plates is emerging as a necessary cooling option for high-density electronics. The use of mini-channels or pins fins to enhance internal heat transfer area inside cold plates requires extensive micro-machining that is relatively time consuming and expensive for mass production. As an alternative approach, inserting and bonding pre-manufactured metal foams into hollow bodies are explored as a potentially inexpensive means to enhance the interior heat transfer area of cold plates. One key aspect of the performance of metal foams in cold plates is the thermal contact resistance in the bonding between the foam and the substrate. This project predicts the contact resistance using measurements of different foam types (pure Cu and Cu with oxide), porosities (63%, 80%, 93%, and 95%) and thicknesses (4 mm, 8 mm, and 10 mm). These measurements are carried out with and without the use of thermal interface material (TIM) pads. A theory is proposed and implemented to estimate the contact and foam thermal resistances, but further work is needed to gain confidence in the results. Observations suggest that different thermal behavior is seen for the Cu foams compared to the Cu with oxide foams, and that the use of TIM pads can achieve 10x to 40x reduction in overall thermal resistance for highly porous foams bonded on Cu substrates.

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