• Title/Summary/Keyword: 전도열전달율

Search Result 3, Processing Time 0.016 seconds

Enhancement Thermal Conductivity of Nanofluids with Electric Double Layer (EDL) (전기이중층에 의한 나노유체의 열전달율 향상)

  • Jung, Jung-Yeul;Yoo, Jung-Yul
    • Proceedings of the KSME Conference
    • /
    • 2007.05b
    • /
    • pp.2160-2164
    • /
    • 2007
  • In this study, the mechanism of enhanced thermal conductivity is elucidated on the bases of both electric double layer (EDL) and kinetic theory. A novel expression for the thermal conductivity of nanofluids is proposed and verified by applying to $Al_2O_3$ nanofluids with regard to various temperatures, volume fractions and particle sizes. In dilute nanofluids, the effects of Brownian motion and particle interaction on enhancing the thermal conductivity of nanofluids are quite comparable while the effect of particle interaction due to EDL is more prominent in dense nanofluids. The model presented in this paper shows that particle interaction due to the electrical double layer is the most responsible for the enhancement of thermal conductivity of nanofluids.

  • PDF

Study on the Characteristics of Conduction Heat Transfer According to the Heating Temperature of a Composite Wall in a Light-weight Partition (경량칸막이 복합벽체의 가열온도에 따른 전도 열전달 특성 연구)

  • Park, Sang-Min;Choi, Su-Gil;Kim, Si-Kuk
    • Fire Science and Engineering
    • /
    • v.33 no.1
    • /
    • pp.60-68
    • /
    • 2019
  • The paper reports the characteristics of conduction heat transfer to the backside part according to the heating temperature of a composite wall in a lightweight partition used for indoor space compartments. Stud partitions, SGP partitions, sandwich panels, urethane foam panels, and glass wool panels. which are generally used as light-weight partition walls, were selected as experiment samples, and the characteristics of conduction heat transfer to the backside part as the top surface were analyzed by applying heating temperatures of $200^{\circ}C$, $300^{\circ}C$, $400^{\circ}C$, and $500^{\circ}C$ to the bottom surface for 1800 s. According to the experimental results, the maximum backside temperatures at the maximum heating temperature of $500^{\circ}C$ was $51.6^{\circ}C$, $63.6^{\circ}C$, $317.2^{\circ}C$, $124.9^{\circ}C$, and $42.2^{\circ}C$ for the stud partition, SGP partition, sandwich panel, urethane foam panel, and glass wool panel, respectively. The maximum conduction heat- transfer rates at $500^{\circ}C$ were 17.16 W, 18.39 W, 136.65 W, 14.34 W, and 5.57 W for the stud partition, SGP partition, sandwich panel, urethane foam, and glass wool panel, respectively.

Study on the Conduction Heat Transfer Characteristics According to the Heating Temperature of Lightweight Panel Wall material (경량칸막이 벽체재료의 수열온도에 따른 전도 열전달 특성 연구)

  • Park, Sang-Min;Lee, Ho-Sung;Choi, Su-Gil;Kim, Si-Kuk
    • Fire Science and Engineering
    • /
    • v.32 no.1
    • /
    • pp.46-56
    • /
    • 2018
  • The paper relates to a study on the conduction heat transfer characteristics according to the heating temperature of lightweight panel wall material. Plywoods, marbles, heat resistant glasses, as well as general gypsum board and fire-proof gypsum board, which have been widely used for lightweight panel wall material, were selected as experiment samples, and heating temperatures were set as $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$ and $600^{\circ}C$. Next, each of the heating temperatures were introduced on the bottom part of the wall material for 30 minutes, and analyses were made on the heat transfer characteristics to the backside part on the top part through conduction. As results of the experiment, the maximum backside temperatures were measured up to $190^{\circ}C$ for a general gypsum board, $198^{\circ}C$ for a fire-proof gypsum board, $189^{\circ}C$ for a plywood, $321^{\circ}C$ for a marble, and $418^{\circ}C$ for a heat resistant glass as heating temperatures were introduced maximum of $600^{\circ}C$. In addition, the maximum change rate of conduction heat transfer were measured up to 85 W for a general gypsum board, 95 W for a fire-proof gypsum board, 67 W for a plywood, 1686 W for a marble, and 3196 W for a heat resistant glass as the maximum heating temperatures were introduced up to $600^{\circ}C$. Also, carbonization characteristics of the wallpapers were measured to visually check the danger of conduction heat transfer, and the results showed that smokes were first generated on the attached wallpapers for the heating temperature $600^{\circ}C$, which were 1021 s for a general gypsum board, 978 s for a fire-proof gypsum board, 1395 s for a plywood, 167 s for a marble, and 20 s for a heat resistant glass, and that the first generation of carbonization were 1115 s for a general gypsum board, 1089 s for a fire-proof gypsum board, 1489 s for a plywood, 192 s for a marble, and 36 s for a heat resistant glass.