Shape factors for conductive heat flow

AIChE Journal ◽  
1958 ◽  
Vol 4 (3) ◽  
pp. 330-331 ◽  
Author(s):  
Julian C. Smith ◽  
John E. Lind ◽  
David S. Lermond
Keyword(s):  
Heat Flow ◽  
Conductive Heat ◽  
Shape Factors ◽  
Conductive Heat Flow

Thermal metamaterials for radiative plus conductive heat flow control

2020 ◽  
Vol 116 (19) ◽  
pp. 191902
Author(s):  
Ercan M. Dede ◽  
Ziqi Yu ◽  
Paul Schmalenberg ◽  
Hideo Iizuka
Keyword(s):  
Heat Flow ◽  
Flow Control ◽  
Conductive Heat ◽  
Conductive Heat Flow

Experimental Analysis of Thermal and Electric Transport Characteristics of Nano-Gaps

2011 ◽  
Author(s):  
Kohei Ito ◽  
Tomoaki Hagio ◽  
Akira Matsuo ◽  
Yasushi Iwaisako ◽  
Osamu Nakabeppu
Keyword(s):  
Heat Flow ◽  
Low Temperature ◽  
High Performance ◽  
Theoretical Study ◽  
Tunneling Current ◽  
Conductive Heat ◽  
Electric Transport ◽  
Probe Diameter ◽  
Thermoelectric Voltage ◽  
Conductive Heat Flow

We conducted an experiment to demonstrate the thermoelectric nano-gap, which is recently expected to own high performance, in principle, because it does not have conductive heat flow between the high and low temperature region. In this study, the thermoelectric nano-gap is realized with a pair of probe and substrate where they are finely positioned. A temperature difference of ca. 10 K is imposed to the nano-gap under vacuum circumstances. A representative thermoelectric voltage, tunneling-current and gap were 250 μV, 0.3 nA and 50 nm. The obtained voltage and current, with assuming an effective probe-diameter of 10 nm, roughly agreed to a theoretical study (G. Despesse and T. Jager, J. Appl. Phys., Vol.96, p.5026-, 2004). However, the obtained gap was 25 times larger than that from the theoretical study.

Natural convection in a corrugated slot

2017 ◽  
Vol 815 ◽  
pp. 537-569 ◽  
Author(s):  
Arman Abtahi ◽  
J. M. Floryan
Keyword(s):  
Natural Convection ◽  
Heat Flow ◽  
Convective Heat ◽  
Phase Difference ◽  
Conductive Heat ◽  
Heat Transfer Augmentation ◽  
Conductive Heat Flow ◽  
Secondary Motion ◽  
Prandtl Numbers

Analysis of natural convection in a horizontal slot formed by two corrugated isothermal plates has been carried out. The analysis is limited to subcritical Rayleigh numbers$Ra$where no secondary motion takes place in the absence of corrugations. The corrugations have a sinusoidal form characterized by the wavenumber, the upper and lower amplitudes and the phase difference. The most intense convection occurs for corrugation wavelengths comparable to the slot height; it increases proportionally to$Ra$and proportionally to the corrugation height. Placement of corrugations on both plates may either significantly increase or decrease the convection depending on the phase difference between the upper and lower corrugations, with the strongest convection found for corrugations being in phase, i.e. a ‘wavy’ slot, and the weakest for corrugations being out of phase, i.e. a ‘converging–diverging’ slot. It is shown that the shear forces would always contribute to the corrugation build-up if erosion was allowed, while the role of pressure forces depends on the location of the corrugations as well as on the corrugation height and wavenumber, and the Rayleigh number. Placing corrugations on both plates results in the formation of a moment which attempts to change the relative position of the plates. There are two limiting positions, i.e. the ‘wavy’ slot and the ‘converging–diverging’ slot, with the latter being unstable. The system would end up in the ‘wavy’ slot configuration if relative movement of the two plates was allowed. The presence of corrugations affects the conductive heat flow and creates a convective heat flow. The conductive heat flow increases with the corrugation height as well as with the corrugation wavenumber; it is largest for short-wavelength corrugations. The convective heat flow is relevant only for wavenumbers of$O(1)$, it increases proportionally to$Ra^{3}$and proportionally to the second power of the corrugation height. Convection is qualitatively similar for all Prandtl numbers$Pr$, with its intensity increasing for smaller$Pr$and with the heat transfer augmentation increasing for larger$Pr$.

scholarly journals Heat flow from the Earth interior as indicator of deep processes

Georesursy ◽  
2018 ◽  
Vol 20 (4) ◽  
pp. 366-376 ◽  
Author(s):  
B. Polyak ◽  
M. Khutorskoy
Keyword(s):  
Heat Flow ◽  
Hydrothermal Activity ◽  
Conductive Heat ◽  
Radiogenic Heat ◽  
The Earth ◽  
Open Discharge ◽  
Conductive Heat Flow ◽  
Different Depths ◽  
Tectonic Movements ◽  
Energy Aspects

The energy aspects of the problem of intraterrestrial heat transfer in various forms are discussed. Endogenous causes of conductive heat flow dispersion − radiogenic heat generation, tectonic movements and magmatism (volcanism), including its latent and open discharge in the form of volcanic and hydrothermal activity are considered. The geological ordering of the heat flow in the continental crust is related to convective discharge of the heat and mass flux from the mantle, marked by the isotopic composition of helium in freely circulating underground fluids. The combined transport of heat and helium, as well as the correlation of He isotopic compositions in volcanic and hydrothermal gases and Sr compositions in young lavas, testify to the silicate nature of the heat and mass flow emanating from the mantle reservoirs of different depths.

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