scholarly journals Thermogravitational Convective Flow and Energy Transport in an Electronic Cabinet with a Heat-Generating Element and Solid/Porous Finned Heat Sink

Mathematics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 34
Author(s):  
Xuan Hoang Khoa Le ◽  
Ioan Pop ◽  
Mikhail A. Sheremet
Keyword(s):  
Heat Transfer ◽  
Viscous Fluid ◽  
Heat Sink ◽  
Energy Transport ◽  
Cooling System ◽  
Transport Processes ◽  
Governing Equations ◽  
Energy Efficient Buildings ◽  
Porous Fins ◽  
Cooling Cavity

Heat transfer enhancement poses a significant challenge for engineers in various practical fields, including energy-efficient buildings, energy systems, and aviation technologies. The present research deals with the energy transport strengthening using the viscous fluid and solid/porous fins. Numerical simulation of natural convective energy transport of viscous fluid in a cooling cavity with a heat-generating element placed in a finned heat sink was performed. The heat-generating element is characterized by constant volumetric heat generation. The Darcy–Brinkman approach was employed for mathematical description of transport processes within the porous fins. The governing equations formulated using the non-primitive variables were solved by the finite difference method of the second-order accuracy. The influence of the fins material, number, and height on the flow structure and heat transfer was also studied. It was found that the mentioned parameters can be considered as control characteristics for heat transfer and fluid flow for the cooling system.

scholarly journals Enhanced heat transfer characteristics of conjugated air jet impingement on a finned heat sink

2017 ◽  
Vol 21 (1 Part A) ◽  
pp. 279-288 ◽  
Author(s):  
Shuxia Qiu ◽  
Peng Xu ◽  
Liping Geng ◽  
Arun Mujumdar ◽  
Zhouting Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Cooling System ◽  
Flow Characteristics ◽  
Jet Impingement ◽  
Transfer Performance ◽  
Transfer Enhancement ◽  
Air Jet

Air jet impingement is one of the effective cooling techniques employed in micro-electronic industry. To enhance the heat transfer performance, a cooling system with air jet impingement on a finned heat sink is evaluated via the computational fluid dynamics method. A two-dimensional confined slot air impinging on a finned flat plate is modeled. The numerical model is validated by comparison of the computed Nusselt number distribution on the impingement target with published experimental results. The flow characteristics and heat transfer performance of jet impingement on both of smooth and finned heat sinks are compared. It is observed that jet impingement over finned target plate improves the cooling performance significantly. A dimensionless heat transfer enhancement factor is introduced to quantify the effect of jet flow Reynolds number on the finned surface. The effect of rectangular fin dimensions on impingement heat transfer rate is discussed in order to optimize the cooling system. Also, the computed flow and thermal fields of the air impingement system are examined to explore the physical mechanisms for heat transfer enhancement.

scholarly journals Numerical Assessment of Heat Transfer and Entropy Generation of a Porous Metal Heat Sink for Electronic Cooling Applications

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3851
Author(s):  
Hamed Rasam ◽  
Prosun Roy ◽  
Laura Savoldi ◽  
Shabnam Ghahremanian
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Entropy Generation ◽  
Heat Sink ◽  
Cooling System ◽  
Solid Phase ◽  
Porous Metal ◽  
Electronic Equipment ◽  
Bejan Number ◽  
Pore Density

In the present study, the thermal performance of an electronic equipment cooling system is investigated. The heat sink used in the current cooling system consists of a porous channel with a rectangular cross-section that is assumed to be connected directly to the hot surface of an electronic device. In this modeling, a fully developed flow assumption is used. The Darcy–Brinkman model was used to determine the fluid flow field. Since using the local thermal equilibrium (LTE) model may provide results affected by the error in metal foams, in the present research, an attempt has first been made to examine the validity range of this model. The local thermal non-equilibrium (LTNE) model taking into account the viscous dissipation effect was then used to determine the temperature field. To validate the numerical solution, the computed results were compared with other studies, and an acceptable agreement was observed. Analysis of the temperature field shows that if the fluid–solid-phase thermal conductivity ratio is 1 or the Biot number has a large value, the difference between the temperature of the solid phase and the fluid phase decreases. Moreover, the effect of important hydrodynamic parameters and the porous medium characteristics on the field of hydrodynamic, heat, and entropy generation was studied. Velocity field analysis shows that increasing the pore density and reducing the porosity cause an increase in the shear stress on the walls. By analyzing the entropy generation, it can be found that the irreversibility of heat transfer has a significant contribution to the total irreversibility, leading to a Bejan number close to 1. As a guideline for the design of a porous metal heat sink for electronic equipment, the use of porous media with low porosity reduces the total thermal resistance and improves heat transfer, reducing the total irreversibility and the Bejan number. Moreover, the increasing of pore density increases the specific porous surface; consequently, it reduces the total irreversibility and Bejan number and improves the heat transfer.

Performance Assessment of Single and Multiple Jet Impingement Configurations in a Refrigeration-Based Compact Heat Sink for Electronics Cooling

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Pablo A. de Oliveira ◽  
Jader R. Barbosa
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Cooling System ◽  
Electronics Cooling ◽  
Jet Impingement ◽  
Small Scale ◽  
Two Phase ◽  
R 134A ◽  
Steady State Heat Transfer ◽  
Vapor Compression Cooling

The performance of a novel impinging two-phase jet heat sink operating with single and multiple jets is presented and the influence of the following parameters is quantified: (i) thermal load applied on the heat sink and (ii) geometrical arrangement of the orifices (jets). The heat sink is part of a vapor compression cooling system equipped with an R-134a small-scale oil-free linear motor compressor. The evaporator and the expansion device are integrated into a single cooling unit. The expansion device can be a single orifice or an array of orifices responsible for the generation of two-phase jet(s) impinging on a surface where a concentrated heat load is applied. The analysis is based on the thermodynamic performance and steady-state heat transfer parameters associated with the impinging jet(s) for single and multiple orifice tests. The two-phase jet heat sink was capable of dissipating cooling loads of up to 160 W and 200 W from a 6.36 cm2 surface for single and multiple orifice configurations, respectively. For these cases, the temperature of the impingement surface was kept below 40 °C and the average heat transfer coefficient reached values between 14,000 and 16,000 W/(m2 K).

scholarly journals Steady Flow over a Rotating Disk in Porous Medium with Heat Transfer

2009 ◽  
Vol 14 (1) ◽  
pp. 21-26 ◽  
Author(s):  
H. A. Attia
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Energy Transfer ◽  
Viscous Fluid ◽  
Steady Flow ◽  
Numerical Solutions ◽  
Rotating Disk ◽  
Incompressible Viscous Fluid ◽  
Governing Equations ◽  
Temperature Distributions

The steady flow of an incompressible viscous fluid above an infinite rotating disk in a porous medium is studied with heat transfer. Numerical solutions of the nonlinear governing equations which govern the hydrodynamics and energy transfer are obtained. The effect of the porosity of the medium on the velocity and temperature distributions is considered.

scholarly journals REDUCING TEMPERATURE OF CYLINDER LINER DUE TO APPLICATION OF HEAT CARRIER WITH HIGH-CONDUCTIVE MULTIGRAPHENE NANOPARTICLES

2019 ◽  
pp. 56-62
Author(s):  
Roman Vladimirovich Gorshkov
Keyword(s):  
Heat Transfer ◽  
Base Fluid ◽  
Cooling System ◽  
Solid Phase ◽  
Combustion Engine ◽  
Cylinder Liner ◽  
Heat Conducting ◽  
Piston Group ◽  
Cylinder Piston ◽  
Cooling Cavity

The paper considers one of the promising ways to influence the heat transfer in the cooling system of a cylinder-piston group, which is to improve physical properties of coolants. It has been stated that the development of nanotechnology has recently made it possible to significantly increase the thermal conductivity coefficient of base coolant - an aqueous solution of ethylene glycol due to its modification by high-conductive solid multigraphene nanoparticles. The resulting stable two-phase suspensions based on the base coolant and particles of the solid phase are called nanofluids. To evaluate the increase in heat transfer at the “wall-coolant” boundary and the decrease of temperature of this wall when applying nanofluid in the engine cooling system as compared to the base fluid, an experimental setup was developed for simulating the flow of coolant in the annular channel of the cooling cavity of the cylinder liner and the conditions determining the heat transfer in its cooling cavity. As a result of conducting a series of experiments under similar test conditions, a significant increase in the heat transfer coefficient was found at the boundary of the “liner wall-liquid” due to the use of nanofluids with highly heat-conducting multigraphene nanoparticles compared to the base fluid. This led to a decrease in the temperature of the cylinder liner. Reducing the temperature of the heat-loaded engine parts allows to increase the reliability of the promising and forced diesel engines, to increase the degree of boosting at the average effective pressure while maintaining the permissible temperature level of the parts of the cylinder-piston group. Intensification of heat transfer at the “wall-liquid” interface contributes to an increase in the thermal efficiency of various heat exchangers as part of an internal combustion engine associated with the main circuit of the cooling system.

Cooling Performances of Perforated-Finned Heat Sinks

2016 ◽  
Author(s):  
Mohammad Reza Shaeri ◽  
Bradley Richard ◽  
Richard Bonner
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Sink ◽  
Cooling System ◽  
Thermal Characteristics ◽  
Heat Sinks ◽  
Pumping Power ◽  
Maximum Heat ◽  
Maximum Heat Transfer

Cooling performances of perforated-finned heat sinks (PFHS) are investigated in the laminar forced convection heat transfer mode, through detailed experiments. Perforations like windows with square cross sections are placed on the lateral surfaces of the fins. Cooling performances are evaluated due to changes in both porosities and perforation sizes. Thermal characteristics are reported based on pumping power, in order to provide more practical insight about performances of PFHSs in real applications. It is found that at a constant perforation size, there is an optimum porosity that results in the largest heat transfer coefficient. For a fixed porosity, increasing the number of perforations (reducing the perforation size) results in an enhancement of heat transfer rate due to repeated interruption of the thermal boundary layer. The opposite trend is observed for PFHSs with larger perforation sizes. This indicates that there is an optimum perforation size and distance between perforations in order to achieve the maximum heat transfer coefficients at a constant porosity. Also, a PFHS results in a smaller temperature non-uniformity across the heat sink base, as well as a more rapid reduction in temperature non-uniformity on the heat sink base by increasing pumping power. In addition, the advantage of a PFHS to reduce the overall weight of the cooling system is incorporated into thermal characteristics of the heat sinks, and demonstrated by the mass specific heat transfer coefficient.

Challenges in Microscale Conductive and Radiative Heat Transfer

1994 ◽  
Vol 116 (4) ◽  
pp. 799-807 ◽  
Author(s):  
C. L. Tien ◽  
G. Chen
Keyword(s):  
Heat Transfer ◽  
Radiative Heat ◽  
Energy Transport ◽  
Optoelectronic Devices ◽  
Transport Processes ◽  
Future Research ◽  
Conductive Heat ◽  
Microscale Heat Transfer ◽  
Definition Of ◽  
Thermal Energy Transport

This work addresses challenges in the emerging field of microlength scale radiative and conductive heat transfer in solids and recommends specific directions of future research. Microlength scale heat transfer involves thermal energy transport processes in which heat carrier characteristic lengths become comparable to each other or the characteristic device dimension. Identification of these characteristic lengths leads to the definition of different microscale heat transfer regimes. A review of the theoretical bases describing heat transfer in each regime is followed by a discussion of the obstacles confronted in current research. Engineering challenges are illustrated with the applications of microscale heat transfer in cryogenic systems, material processing, and electronic, optical, and optoelectronic devices. The experimental difficulties discussed have hampered the development of microscale heat transfer research and deserve great efforts to overcome them.

scholarly journals Numerical Simulation of Solid and Porous Fins’ Impact on Heat Transfer Performance in a Differentially Heated Chamber

Mathematics ◽  
2022 ◽  
Vol 10 (2) ◽  
pp. 263
Author(s):  
Le Xuan Hoang Khoa ◽  
Ioan Pop ◽  
Mikhail A. Sheremet
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Transfer Performance ◽  
Energy Transport ◽  
Heated Wall ◽  
Transfer Performance ◽  
Finite Difference Technique ◽  
Good Technique ◽  
Vertical Walls ◽  
Porous Fins

The development of different industrial fields, including mechanical and power engineering and electronics, demands the augmentation of heat transfer in engineering devices. Such enhancement can be achieved by adding extended heat transfer surfaces to the heated walls or heat-generating elements. This investigation is devoted to the numerical analysis of natural convective energy transport in a differentially heated chamber with isothermal vertical walls and a fin system mounted on the heated wall. The developed in-house computational code has been comprehensively validated. The Forchheimer–Brinkman extended Darcy model has been employed for the numerical simulation of transport phenomena in a porous material. The partial differential equations written, employing non-primitive variables, have been worked out by the finite difference technique. Analysis has been performed for solid and porous fins with various fin materials, amounts and heights. It has been revealed that porous fins provide a very good technique for the intensification of energy removal from heated surfaces.

Heat Transfer of Oscillating Fluid through Finned Heat Sink with Top Bypass Clearance

2013 ◽  
Vol 479-480 ◽  
pp. 192-196
Author(s):  
Tzer Ming Jeng ◽  
Sheng Chung Tzeng ◽  
Wei Ting Hsu ◽  
Guan Wei Xu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Steady Flow ◽  
Forced Convection ◽  
Flow Rate ◽  
Heat Sink ◽  
Cooling System ◽  
Oscillating Flow ◽  
Transfer Enhancement ◽  
Cooling Performance

This work experimentally investigated the effect of the oscillating flow on the heat transfer enhancement of the finned heat sink with top bypass clearance. The cooling system of the finned heat sink usually employs the steady flow with fixed flow rate to complete the objective of forced convection. This work designed and manufactured a device to oscillate air flow. The experimental results indicate that it would obtain 10~34% heat-transfer increment for the oscillating-flow cases with sufficiently small bypass clearance. It demonstrates that the oscillating flow does promote the cooling performance of finned heat sink.

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