• Proceedings of the KSME Conference
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• 2008.11a
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• pp.408-409
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• 2008

This paper presents a new development for topology optimization of heat-dissipating structure with forced convection. To cool down electric devices or machines, two types of convection models have been widely used: Natural convection model with a large Archimedes number and Forced convection with a small Archimedes number. Nowadays, many engineering application areas such as electrochemical conversion device or fuel cell devices adopt the forced convection to transfer generated heat. Therefore, to our knowledge, it becomes an important issue to design flow channels inside which generated heat transfer. Thus, this paper studies optimal topological designs considering fluid-heat interaction. To consider the effect of the advection in the heat transfer problem, the incompressible Navier-stokes equation is solved. This paper numerically studies the coupling phenomena and presents optimal channel design considering forced convection.

• Corrosion Science and Technology
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• v.19 no.1
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• pp.23-30
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• 2020

Heat sinks are most widely used in thermal management systems; however, the heat dissipation efficiency is usually limited. Therefore, in order to increase heat dissipation efficiency of the heat sink, the heat-dissipating paint using 2D materials (hexagonal boron nitride (h-BN) and graphene) as thermally conductive additive was designed and evaluated in the present study. The heat dissipation performance of the paint was calculated from temperature difference between the paint-coated and -uncoated specimens mounted on the heat source. The highest heat dissipation performance was obtained when the ratio of h-BN to resin was 1/10 in the paint. In addition, further reduction in the temperature of the test specimen by 6.5 ℃ was achieved. The highest heat dissipation performance of the paint prepared using graphene was achieved at a 1/50 ratio of graphene to the resin, and a 6.5 ℃ reduction was attained. In addition, graphene exhibited enhanced corrosion resistance property of heat-dissipating paint by inhibiting the growth of the paint blisters.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.12
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• pp.82-90
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• 2019

This analysis demonstrates the effective removal of heat generated from a solar panel's output degradation factor solar cells (the solar panel's output deterioration factor), and solves the problems of oxidation and corrosion in existing metal heat sinks. The heat-dissipating test specimen was prepared using carbon materials; then, its thermal conductivity and its effectiveness in reducing temperatures were studied using heat transfer numerical analysis. As a result, the test specimen of the 30g/㎡ basis weight containing 80% of carbon fiber impregnated with carbon ink showed the highest thermal conductivity 6.96 W/(m K). This is because the surface that directly contacted the solar panel had almost no pores, and the conduction of heat to the panels appeared to be active. In addition, a large surface area was exposed to the atmosphere, which is considered advantageous in heat dissipation. Finally, numerical analysis confirmed the temperature reduction effectiveness of 2.18℃ in a solar panel and 1.08℃ in a solar cell, depending on the application of heat dissipating materials.

• Composites Research
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• v.35 no.6
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• pp.431-438
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• 2022

Efficient heat dissipation in current electronics is crucial to ensure the best performance and lifespan of the devices along with the users' safety. Materials with high thermal conductivity are often used to dissipate the generated heat from the electronics to the surroundings. For this purpose, polymer composites have been attracted much attention as they possess advantages rooted from both polymer matrix and thermally conductive filler. In order to meet the thermal conductivity required by relevant industries, composites with high filler loadings (i.e., >60 vol%) have been fabricated. At such high filler loadings, however, composites lose benefits originated from the polymer matrix. To achieve high thermal conductivity at a relatively low filler loading, therefore, constructing the heat conduction pathway by controlling filler structure within the composites may represent a judicious strategy. To this end, this review introduces several recent approaches to manufacturing heat dissipating materials with high thermal conductivity by manipulating thermally conductive filler structures in polymer composites.

• Journal of the Korean Solar Energy Society
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• v.35 no.3
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• pp.81-91
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• 2015

LED has received intensive research attention due to its long life, high efficacy, fast response and wide colour availability, and has secured extensive application areas. However, LED chips within the modules convert only fraction of electric energy into light, and majority of supplied energy needs to be dissipated as heat, which challenges in the performance and life of the LED modules. IEC 62717 specifies the performance requirements for LED modules together with the test methods and conditions. The present study examined the influence of different design parameters on performance temperature through series of experiments and numerical simulations. The economic means to change the module performance temperature during the measurement of mandatory markings were suggested based on predicted cooling performances.

• Composites Research
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• v.35 no.3
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• pp.175-181
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• 2022

Due to the increasing number of wireless communication devices in mmWave frequency bands, there is a high demand for electromagnetic interference (EMI) shielding and heat dissipating materials to avoid device malfunctions. This paper proposes an EMI shielding composite film with a high heat dissipation characteristic. To achieve this, a conductive grid is integrated with a polymer-based composite layer including magnetic and heat dissipating filler materials. A high shielding effectiveness (>40 dB), low reflection shielding effectiveness (<3 dB), high thermal conductivity (>10 W/m·K), thin thickness (<500 ㎛) are simultaneously achieved with a tailored design of composite layer compositions and grid geometries in 5G communication band of 26.5 GHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.530-536
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• 2021

This paper presents the performance measurement results of a hybrid sheet with both shielding and heat dissipation functions developed by laminating copper mesh sheets and natural graphite sheets, which are used widely as electromagnetic shielding and heat-dissipating materials in electronic devices, without a pressure-sensitive adhesive (PSA). The results were compared by measuring the vertical and horizontal thermal conductivity with two other products to confirm the heat dissipation performance. A radiation emission test confirmed the electromagnetic shielding performance using a 3m electromagnetic anechoic chamber according to the CISPR 11 standard. In the case of vertical thermal conductivity, the proposed hybrid sheet was approximately 8.63 times higher than that of an aluminum sheet with heat dissipation coating and 18.7 times higher than that of a copper sheet laminated with artificial graphite with PSA. The proposed hybrid sheet was approximately 0.64 times that of the sheet, and approximately 1.76 times that of the heat-dissipated aluminum sheet in case of horizontal thermal conductivity. Measurements after applying each sheet in the same heat source revealed the proposed hybrid sheet to have the best heat dissipation performance. The radiation emission test showed that significantly radiation noise had been removed.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.1
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• pp.51-57
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• 2009

In this study, a new topology optimization method is developed to design heat-dissipating structure with forced convection. To cool down electrical devices or mechanical machines, two types of convection models have been widely used: the natural convection model with a large Archimedes number and the forced convection with a small Archimedes number. In these days, lots of engineering application areas such as electrochemical conversion devices (Fuel cell) or rocket propulsion engines adopt the forced convection to dissipate the generated heat. Therefore, to our knowledge, it becomes an important issue to design flow channels inside which the generated heat dissipate. Thus, this paper studies optimal topological designs considering fluid-heat interactions. To consider the effect of the advection in the heat transfer problem, the incompressible Navier-stokes equation is solved. This paper numerically studies the coupling phenomena and presents optimal channel design considering forced convection.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.7
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• pp.623-629
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• 2004

Rapid development of electronic technology requires small size, high density packaging and high power of electronic devices, which result in more heat generation by the electronic system. Present cooling technology may not be adequate for the thermal management in the current state-of-the-art electronic equipment. Forced convective heat transfer in a channel filled with pin-fin array is studied experimentally in this paper as an alternative cool-ing scheme for a high heat-dissipating equipment. Various configurations of the pin-fin array are selected in order to find out the effect of spacing and diameter of the pin-fin on the heat transfer and pressure drop characteristics. In the low porosity region, interfacial heat transfer and pressure drop seem to show different trend compared to the conventional heat transfer process.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2124-2129
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• 2007

A VCHP was fabricated and tested for its thermal performance. The container was made of copper, and the working fluid was water. STS-316 screen of mesh number 100 was inserted as a capillary structure. As a baseline performance, a normal heat pipe of the same dimensions was tested in advance to compare with VCHP, where an inert gas container was attached. The outer diameter of the heat pipe was 12.8 mm and the total length was 600 mm. The evaporator and the condenser lengths were both 200 mm. The thermal load ranged from 20 to 300W. Typical result revealed that the operating temperature of the VCHP stayed almost constant, while that of the normal heat pipe varied as much as 40$^{\circ}C$. Therefore, it was demonstrated that the VCHP is very effective for temperature control of heat-dissipating devices.