Thermal Science and Engineering
Online ISSN : 1882-2592
Print ISSN : 0918-9963
ISSN-L : 0918-9963
Volume 16 , Issue 3
Showing 1-4 articles out of 4 articles from the selected issue
  • Naoki ONO, Takahiro YOSHIDA, Takahiro KANEKO, Shotaro NISHIGUCHI, Masa ...
    2008 Volume 16 Issue 3 Pages 79-85
    Published: 2008
    Released: September 11, 2008
    JOURNALS FREE ACCESS
    The temperature dependency of surface tension of aqueous solutions of some alcohol such as butanol behaves in a nonlinear manner. Namely, the value of surface tension tends to increase, when the solution is heated beyond a temperature. This type of solution is named “nonlinear thermocapillary solution” here. The direction of thermocapillary force in liquid film of the solution on a heated surface acts in the same direction to that of the solutocapillary force. This characteristic will be more marked in small scale systems such as mini⁄micro channels. In this study the liquid behavior of the solution in flow boiling experiments with mini⁄micro tubes was investigated. Butanol aqueous solutions were adopted as test fluids. Pure water and ethanol aqueous solution were also used for comparison. The aim of the study is to observe the liquid motion and to investigate temperature fluctuation in mini⁄micro channels with inner diameter of 1 mm and 0.42 mm. The surface temperature of the tube was measured by using fine K-type thermocouples at the surface of the tubes and the liquid motion was observed by CCD camera system.
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  • Kakeru KAGATA, Tetsuya YAMADA, Atsumasa YOSHIDA
    2008 Volume 16 Issue 3 Pages 87-93
    Published: 2008
    Released: September 11, 2008
    JOURNALS FREE ACCESS
    In order to measure the thermal properties of biological materials simply and precisely, photoacoustic method, which is one of non-contact and non-destructive techniques for measuring thermophysical properties of various materials, is applied to human skin. A newly developed open-type cell is introduced to make an acoustic chamber. The cell possesses a cylindrical chamber with one end open and is completed by sealing with human skin. Comparisons of experimental data with theoretical calculations ensure that reasonable values of skin′s thermal effusivity are able to be obtained. The values measured from 6 persons show that there are some differences in thermal effusivity among individuals and parts.
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  • Kenichi TEZUKA, Sanehiro WADA, Michitsugu MORI, Hiroshige KIKURA, Masa ...
    2008 Volume 16 Issue 3 Pages 95-104
    Published: 2008
    Released: September 11, 2008
    JOURNALS FREE ACCESS
    Thermal powers of nuclear reactors are calculated by the enthalpy difference between reactor feed water and main steam. Improvement of the measurement accuracy in the flow rate measurements of reactor feed water enables us to uprate reactor thermal power, called MUR (Measurement Uncertainly Recapture) uprate. The ultrasonic pulse Doppler system is expected to be a suitable method featuring the capability o measuring the flow profile directly in a pipe. For the optimum measurements, ultrasound path from ultrasonic transducer into the fluid through steel pipe wall should be carefully predicted in high temperature water. This paper presents analytical results of ultrasound propagation using FEM simulation code and experimental results of pipe flow rate at high temperature thermal conditions.
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  • Yohei ITO, Koji TAKAHASHI, Norsyazwan HILMI, Xing ZHANG
    2008 Volume 16 Issue 3 Pages 105-111
    Published: 2008
    Released: September 11, 2008
    JOURNALS FREE ACCESS
    A novel method to measure the thermal conductivity of nano scale deposition is developed by using platinum hot film suspended between two terminals. The nano-deposition, which can be built by either focused ion or electron beam, is one of the newest fabrication techniques for three dimensional nano-structure, and can be applied to patterning, repairing, bonding, et al. However, its thermal property is still unknown because the size is too small to measure by the existing thermal sensors. The hot film used here is fabricated by NEMS (Nanoelectromechanical Systems) technology and has enough sensitivity to measure nanoscale materials. Direct current heating method is applied before and after the deposition and the change of averaged temperature increase of the platinum film gives the thermal conductivity of additionally-deposited material by using one-dimensional heat conduction model. As an example, amorphous carbon (a-C) with the thickness of 563 nm is deposited by electron beam induced deposition (EBID) method and thermal conductivity of a-C nano-deposition is obtained to be 0.61 W⁄(m·K) to 0.73 W⁄(m·K) at 100 K to 340 K. In order to confirm the reliability of this method, two-dimensional numerical simulation is conducted and the measuring uncertainty is calculated exactly. The effect of thermal boundary resistance is also treated and discussed. From the comparison of 1D model and 2D simulation, it is found that the deposition extended on the terminals by 1 μm length can decrease the error of 1D model from 5.5 % to 3.1 % but no more extension has little effect to improve the accuracy of this method.
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