Thermal Science and Engineering
Online ISSN : 1882-2592
Print ISSN : 0918-9963
ISSN-L : 0918-9963
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    2019 Volume 27 Issue 2 Pages 53-58
    Published: 2019
    Released: May 06, 2019
    We measured thermal boundary resistance at the organic-inorganic interface to calculate the effective thermal conductivity by changing the thickness of both PEDOT:PSS and Bismuth Telluride in multi-layered thin films. The total thermal resistance of the films as a function of thickness were measured by using a differential 3ω method. organic-inorganic thermal boundary resistance is larger than inorganic-inorganic thermal boundary resistance due to high contrast of mechanical properties between organic and inorganic materials. The measured PEDOT:PSS-Bismuth Telluride thermal boundary resistance was 1.1±0.3×10-7( m2・K ) / W. The measured high thermal boundary resistance can explain the low value of effective thermal conductivity of organic-inorganic composite film.
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  • Fumihiko HIDEYAMA, Yasushi KOITO
    2019 Volume 27 Issue 2 Pages 59-66
    Published: 2019
    Released: May 06, 2019
    This paper describes experimental investigations on heat transfer characteristics of a pulsating heat pipe (PHP) fabricated by a 3-D printer. A transparent ABS (Acrylonitrile Butadiene Styrene) filament was used as a printing material. Three types of PHPs were fabricated by changing a cross-sectional area of a serpentine channel. HFE (Hydro-Fluoro-Ether)-7100 was employed as a working fluid, and its filling ratio was 50 % of a total volume of the serpentine channel. In experiments, an evaporator section of the PHP was heated by a heater and a condenser section was water-cooled using a cooling jacket. Pulsating phenomena of the working fluid were observed through a transparent PHP wall. Temperatures at the evaporator, the adiabatic and the condenser section of the PHP were measured by T-type thermocouples. The heat input was escalated from 4 W while the cooling water temperature and its flow rate were kept at 5.0 ºC and 400 mL/min, respectively. From the experimental results, stable heat transport from the evaporator to the condenser section was confirmed for all types of PHPs. The heat transfer coefficients at the evaporator and the condenser section were evaluated, and the heat transfer characteristics of each PHP were compared. Furthermore, the comparison was also made between the present PHPs and the other ones in literatures.
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