(a) Thermal conductivity of Al71.6Mn17.4Si11 and Al72.6Re17.4Si10 alloys. (b) Schematic illustrations of the thermal rectifier consisting of two different alloys. The interface temperatures, T AB and T BA, are calculated and plotted in (c), and the TRR calculated from the measured thermal conductivity is plotted in (d) with the solid line together with the solid circle indicating the experimentally determined TRR.
Schematic illustration of the experimental setup used in the current study. The temperature of the copper block, which was initially kept at room temperature, was measured as a function of heating time. The heat current was determined from the transient curve of the copper block temperature.
X-ray diffraction patterns of the Al62Cu25.5Fe12.5 quasicrystal, and two 1/1-cubic approximant obtained at Al71.6Mn17.4Si11 at Al72.6Re17.4Si10. The measured XRD patterns definitely indicated that the samples were consisting almost solely of the objective phases.
Transient curve of copper block temperature for the thermal rectifier thatconsists of Al71.6Mn17.4Si11 and Al72.6Re17.4Si10. Two transient curves for three different length ratios, x = L Al-Re-Si/(L Al-Re-Si + L Al-Mn-Si) = 0.4, 0.6, and 0.75, were plotted in (a), (b), and (c), respectively. When Al72.6Re17.4Si10 is located at the higher temperature side, the temperature of copper block shown with the open circles increases faster than the other case due to the larger magnitude of thermal conductivity of Al72.6Re17.4Si10 than that of Al71.6Mn17.4Si11 at high temperatures above 300 K.
Thermal rectification ratio of the rectifier consisting of Al71.6Mn17.4Si11 at Al72.6Re17.4Si10. The calculated value is plotted with solid line, and the experimentally determined ones are indicated with the markers.
Calculated temperature distribution in the thermal rectifier consisting of Al71.6 Mn17.4Si11 at Al72.6Re17.4Si10 when it is located between two heat reservoirs kept at300 K and 500 K. The temperature at a given position is always higher in the case of large heat current.
(a) Thermal conductivity of the Al62Cu25.5Fe12.5 icosahedral quasicrystal and that of four different hypothetical materials. Thermal conductivity of the Al62Cu25.5Fe12.5 icosahedral quasicrystal possesses a drastic increase with increasing temperature. (b) Thermal rectification ratio calculated by assuming that the Al62Cu25.5Fe12.5 icosahedral quasicrystal is combined together with the four different hypothetical materials. The calculation clearly indicates that a large TRR exceeding unity possibly obtainable for the rectifier containing the Al62Cu25.5Fe12.5 icosahedral quasicrystal.
(a) Thermal conductivity of single grained Si and Ge (Ref. 16), and (b) thermal rectification ratio calculated for the thermal rectifier consisting of Al62Cu25.5Fe12.5 icosahedral quasicrystal and the single grained Si or Ge under the conduction of TL = 300 K and T H = 1000 K. Thermal conductivity of Si and Ge decreases with temperature, and varies even high temperature above 500 K in association with their high Debye temperature. This significant temperature dependence of thermal conductivity provides us with a large TRR exceeding unity for the rectifier consisting of the Al62Cu25.5Fe12.5 icosahedral quasicrystal and the single grained Si or Ge.
Article metrics loading...
Full text loading...