• Title/Summary/Keyword: Thermal Conductivity Ratio

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Density and Thermal Conductivity Property of the Lightweight Composite Panel Core According to Pearlite Replacement ratio (펄라이트 치환율에 따른 경량복합패널 심재의 밀도 및 열전도율 특성)

  • Kim, Heon-Tae;Jung, Byeong-Yeol;Lee, Sang-Soo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2014.11a
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    • pp.175-176
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    • 2014
  • Recently, in the apartment house of our country, office building, apartment, and etc, the lightweight composite panel is much used as the partition wall body. This is due to be very convenient when the execution and dismantling is convenient and it forms the space which the consumer in the space desires. Therefore, in this research, the thermal conductivity property of the lightweight composite panel core according to the replacement ratio variation of the pearlite tries to be analyze. As the density test result and replacement ratio of the pearlite increased, the density showed the tendency to rise. the replacement ratio of the pearlite increased, the absorption rate showed the tendency to fall. And this is determined that absorption rate is degraded due to the increase in the density. the thermal conductivity test result and pearlite replacement ratio increased, the tendency that the thermal conductivity increases was represented.

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A Study on the Thermal Insulation Property of Concrete Composites using Light-weight Aggregate (경량골재를 사용한 콘크리트 복합체의 단열성능에 관한 연구)

  • So, Seung-Yeong
    • Journal of the Korea Institute of Building Construction
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    • v.4 no.3
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    • pp.93-100
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    • 2004
  • In recent years, it has widely been studied on the light-weight composites for the purpose of the large space and thermal insulation of building structures. The purpose of this study is to evaluate the properties of light-weight composites made by binders as cement, resin and polymer cement slurry. The concrete composites are prepared with various conditions such as polymer-cement ratio, void-filling ratio, type of resin, filler content and light-weight aggregate content, tested for thermal conductivity. From the test results, the thermal conductivity of concrete composites with the binder of cement tends to decrease with increasing polymer-cement ratio, and to increase with increasing void-filling ratio. The thermal conductivity of concrete composites with the binder of resin are markedly affected by the light-weight aggregate content, type of resin and filler content. The composites made by polymer-modified concrete and polymer cement slurry have a good thermal insulation property. From the this study, we can recommend the proper mix proportions for thermal insulation Panel or concrete. Expecially. the thermal conductivity of concrete composites made by polyurethane resin is almost the same as that of the conventional expanded polystyrene resin.

Free Convective Heat Transfer in a Vertical Channel with Heat Source at the Wall (벽에서 열원이 있는 수직채널안의 자연대류열전달)

  • Pak, Hi-Yong;Doo, Min-Soo
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.14 no.2
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    • pp.108-117
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    • 1985
  • In this study, a numerical analysis was performed for the natural convection heat transfer in a vertical channel which was consisted of two finite-thickness vertical walls with heat source. The ratio of the thermal conductivity of wall to air played an important role in the analysis. The case for which one side wall has protrusion resistances was also examined. The governing equations for the system was discretized by control volume formulation and solved by SIMPLE method. As the result of this study, it was found that the uniform heat flux boundary condition could be applied when the conductivity ratio was below approximately 50 and the uniform temperature boundary condition could be used when the conductivity rat io was over approximately 15,000. However, when the conductivity ratio was between 50 and 15,000, the thermal conductivity ratio value should be considered for the analysis. It was also found that the existence of protrusion resistance influenced the thermal field up to the distance of 3-4 times of the protrusion length.

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Thermoelastic analysis for a slab made of a thermal diode-like material

  • Darwish, Feras H.;Al-Nimr, Mohammad A.;Hatamleh, Mohammad I.
    • Structural Engineering and Mechanics
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    • v.53 no.4
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    • pp.645-659
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    • 2015
  • This research investigates the thermoelastic transient behavior of a thermally loaded slab made of a thermal diode-like material which has two directional thermal conductivity values (low and high). Finite difference analysis is used to obtain the elastic response of the slab based on the temperature solutions. It is found that the rate of heat transfer through the thickness of the slab decreases with reducing the ratio between the low and high thermal conductivity values (R). In addition, reducing R makes the slab less responsive to the thermal load when heated from the direction associated with the low thermal conductivity value.

Measurement of Thermal Conductivity of Foods in Liquid and Solid Phase Using a Thermal Probe

  • Hong, Ji-Hyang;Han, Young-Joe;Chung, Jong-Hoon
    • Food Science and Biotechnology
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    • v.14 no.3
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    • pp.334-339
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    • 2005
  • An instrument using thermal probe method was designed to measure thermal conductivity of liquid and solid foods. Thermal conductivity probe was designed with diameter to length ratio of 100 and diameter of 0.51 mm to minimize axial flow effect on thermal conductivity measurement. Thermal conductivities of distilled/deionized water, glycerin, and beef frankfurter meat were measured at $20-80^{\circ}C$. Mean thermal conductivity values of water showed less than 2.0% difference from several reference values without using time correction factor or probe calibration constant. For glycerin, difference was less than 0.7% from reference values at $20-50^{\circ}C$. Mean values of thermal conductivity for beef frankfurter meat ranged from 0.389 to $0.350\;W/m{\cdot}K$ at $20-80^{\circ}C$.

Thick Graphene Embedded Metal Heat Spreader with Enhanced Thermal Conductivity

  • Park, Minsoo;Chun, Kukjin
    • Journal of Sensor Science and Technology
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    • v.23 no.4
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    • pp.234-237
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    • 2014
  • In this paper, a copper foil-thick grapheme (thin graphite sheet)-copper foil structure is reported to achieve mechanically strong and high thermal conductive layer suitable for heat spreading components. Since graphene provides much higher thermal conductivity than copper, thick graphene embedded copper layer can achieve higher effective thermal conductivity which is proportional to graphene/copper thickness ratio. Since copper is nonreactive with carbon material which is graphene, chromium is used as adhesion layer to achieve copper-thick graphene-copper bonding for graphene embedded copper layer. Both sides of thick graphene were coated with chromium as an adhesion layer followed by copper by sputtering. The copper foil was bonded to sputtered copper layer on thick graphene. Angstrom's method was used to measure the thermal conductivity of fabricated copper-thick graphene-copper structure. The thermal conductivity of the copper-thick graphene-copper structures is measured as $686W/m{\cdot}K$ which is 1.6 times higher than thermal conductivity of pure copper.

Measurement of the Thermal Conductivity of Alumina/Zinc-Oxide/Titanium-Oxide Nanofluids (알루미나/산화아연/이산화티타늄 나노유체의 열전도율 측정)

  • Kim Sang Hyun;Choi Sun Rock;Hong Jonggan;Kim Dongsik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.9 s.240
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    • pp.1065-1073
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    • 2005
  • The thermal conductivity of water- and ethylene glycol-based nanofluids containing alumina $(Al_2O_3)$, zinc oxide (ZnO) and titanium dioxide $(TiO_2)$ nanoparticles is measured by varying the particle diameter and volume fraction. The transient hot-wire method using an anodized tantalum wire for electrical insulation is employed for the measurement. The experimental results show that nanofluids have substantially higher thermal conductivities than those of the base fluid and the ratio of thermal conductivity enhancement increases linearly with the volume fraction. It has been found that the ratio of thermal conductivity enhancement increases with decreasing particle size but no empirical or theoretical correlation can explain the particle-size dependence of the thermal conductivity. This work provides, for the first time to our knowledge, a set of consistent experimental data over a wide range of nanofluid conditions and can therefore serve as a basis for developing theoretical models to predict thermal conduction phenomena in nanofluids.

Effects of Silicone Surfactant on the Cell Size and Thermal Conductivity of Rigid Polyurethane Foams by Environmentally Friendly Blowing Agents

  • Han, Mi-Sun;Choi, Seok-Jin;Kim, Ji-Mun;Kim, Youn-Hee;Kim, Woo-Nyon;Lee, Heon-Sang;Sung, Joon-Yong
    • Macromolecular Research
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    • v.17 no.1
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    • pp.44-50
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    • 2009
  • Rigid polyurethane foams (PUF)s were synthesized with environmentally friendly blowing agents such as a cyclopentane/distilled water (10.0/1.0, pphp) mixture and distilled water only for four different silicone surfactants having different silicone/polyether ratios. An attempt was made to reduce the thermal conductivities of the PUF samples by varying the concentration and the silicone/polyether ratio of the various silicone surfactants. The scanning electron microscopy (SEM) results indicated an optimum concentration of the silicone surfactant of about 1.5 to 2.5 phpp for various surfactants to reduce the cell size and lower the thermal conductivity. The silicone surfactant having a higher silicone/polymer ratio showed a smaller cell size and, therefore, demonstrated the lower thermal conductivity of the PUF samples. From the relation between the thermal conductivity and the cell size of the PUF samples, the smaller cell size improved the thermal insulation property of the rigid PUF for both the PUF samples blown by the cyclopentane/distilled water (10.0/1.0, pphp) mixture and distilled water only. If the blowing agent is fixed, then the cell size is an important factor to decrease the thermal conductivity of the PUF samples. These results indicated that rigid PUF samples having lower thermal conductivity can be obtained by choosing a silicone surfactant containing a higher silicone/polyether ratio, as well as an optimum content of the surfactant.

Insulation Properties of CLC according to Mixing Ratio of EPS Bead (EPS Bead 혼입비율에 따른 CLC의 단열특성)

  • Lee, Jeong-Taek;Lee, Sang-Soo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.05a
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    • pp.45-46
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    • 2023
  • CLC is used as a filling material for many buildings, and according to energy saving design standards, CLC also requires insulation performance. However, it shows lower insulation performance compared to organic insulation, so additional research is needed. Therefore, in this study, the insulation properties of CLC were analyzed by incorporating EPS beads with high insulation performance into CLC. In this experiment, EPS beads and blast furnace slag were replaced, and W/B was fixed at 33%. The EPS Bead mixing ratio was divided into 5 levels: 0, 0.5, 1.0, 1.5, 2.0 (%), and the experimental items were measured for apparent density and thermal conductivity. As a result of the experiment, the apparent density and thermal conductivity tended to decrease as the mixing ratio of EPS beads increased. It is judged that the density decreased due to the low density and the micropores inside, and the thermal conductivity also decreased.

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Sputtering of Multifunctional AlN Passivation Layer for Thermal Inkjet Printhead

  • Park, Min-Ho;Kim, Sang-Ho
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.50-50
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    • 2011
  • The aluminum nitride films were prepared by RF magnetron sputtering using an AlN ceramic target. The crystallinity, grain size, Al-N bonding and thermal conductivity were investigated in dependence on the plasma power densities (4.93, 7.40, 9.87 W/$cm^2$) during sputtering. High thermal conductivity is important properties of A1N passivation layer for functioning properly in thermal inkjet printhead. The crytallinity, grain size, Al-N bonding formation and chemical composition were observed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The AlN thin film was changed from amorphous to crystalline as the power density was increased, and the largest grain size appeared at medium power density. The near stoichiometry Al-N bonding ratio was acquired at medium power density. So, we know that the AlN thin film had better thermal conductivity with crystalline phase and near stoichometry Al-N bonding ratio at 7.40 W/$cm^2$ power density.

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