Effective modulation of the near-field heat flux with radiative thermal switch based on electrochromic effects of tungsten trioxide

2018 ◽  
Vol 218 ◽  
pp. 171-177 ◽  
Author(s):  
Yong Chen ◽  
Zhiheng Zheng ◽  
Yimin Xuan
Keyword(s):  
Heat Flux ◽  
Tungsten Trioxide ◽  
Near Field ◽  
Thermal Switch

scholarly journals Spectral gaps in the near-field heat flux

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
J. E. Pérez-Rodríguez ◽  
G. Pirruccio ◽  
Raúl Esquivel-Sirvent
Keyword(s):  
Heat Flux ◽  
Near Field ◽  
Spectral Gaps

Performance Analysis of Near-Field Thermophotovoltaic With a Multilayer Metallodielectric Emitter

2016 ◽  
Author(s):  
Y. Yang ◽  
J. Y. Chang ◽  
L. P. Wang
Keyword(s):  
Heat Flux ◽  
Power Output ◽  
Indium Tin Oxide ◽  
Effective Medium Theory ◽  
Near Field ◽  
Electrical Power ◽  
Electrical Contacts ◽  
Alumina Layer ◽  
Photon Transport ◽  
Electrical Power Output

The photon transport and energy conversion of a near-field thermophotovoltaic (TPV) system with a selective emitter composed of alternate tungsten and alumina layers and a photovoltaic cell sandwiched by electrical contacts are theoretically investigated in this paper. Fluctuational electrodynamics along with the dyadic Green’s function for a multilayered structure is applied to calculate the spectral heat flux, and photocurrent generation and electrical power output are solved from the photon-coupled charge transport equations. The tungsten and alumina layer thicknesses are optimized to match the spectral heat flux with the bandgap of TPV cell. The spectral heat flux is much enhanced when plain tungsten emitter is replaced with the multilayer emitter due to the mechanism of surface plasmon polariton coupling in the tungsten thin film. In addition, the invalidity of effective medium theory to predict photon transport in the near field with multilayer emitters is discussed. Effects of a gold back reflector and indium tin oxide front coating with nanometer thickness, which could practically act as the electrodes to collect the photon-generated charges on the TPV cell, are explored. Conversion efficiency of 23.7% and electrical power output of 0.31 MW/m2 are achieved at 100 nm vacuum gap when the emitter and receiver are respectively at temperatures of 2000 K and 300 K.

Enhanced heat flux in the scrape-off layer due to electrons accelerated in the near field of lower hybrid grills

1998 ◽  
Vol 38 (6) ◽  
pp. 919-937 ◽  
Author(s):  
M Goniche ◽  
D Guilhem ◽  
P Bibet ◽  
P Froissard ◽  
X Litaudon ◽  
...  
Keyword(s):  
Heat Flux ◽  
Near Field ◽  
Lower Hybrid

scholarly journals Giant heat transfer in the crossover regime between conduction and radiation

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Konstantin Kloppstech ◽  
Nils Könne ◽  
Svend-Age Biehs ◽  
Alejandro W. Rodriguez ◽  
Ludwig Worbes ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Near Field ◽  
Black Body ◽  
Black Body Radiation ◽  
Quantitative Measurements ◽  
Atomic Spacing ◽  
Large Heat ◽  
Vacuum Gaps ◽  
Near Field Scanning

Abstract Heat is transferred by radiation between two well-separated bodies at temperatures of finite difference in vacuum. At large distances the heat transfer can be described by black body radiation, at shorter distances evanescent modes start to contribute, and at separations comparable to inter-atomic spacing the transition to heat conduction should take place. We report on quantitative measurements of the near-field mediated heat flux between a gold coated near-field scanning thermal microscope tip and a planar gold sample at nanometre distances of 0.2–7 nm. We find an extraordinary large heat flux which is more than five orders of magnitude larger than black body radiation and four orders of magnitude larger than the values predicted by conventional theory of fluctuational electrodynamics. Different theories of phonon tunnelling are not able to describe the observations in a satisfactory way. The findings demand modified or even new models of heat transfer across vacuum gaps at nanometre distances.

A Tunable Magnetomechanical Thermal Switch for Thermal Management Purposes

2009 ◽  
Author(s):  
Katherine E. Bulgrin ◽  
Y. Sungtaek Ju ◽  
Greg P. Carman ◽  
Adrienne S. Lavine
Keyword(s):  
Heat Flux ◽  
Heat Source ◽  
Thermal Management ◽  
Ferromagnetic Material ◽  
Physical Structure ◽  
Device Performance ◽  
Cold Surface ◽  
Turn On ◽  
Thermal Switch ◽  
Effective Conductance

This work proposes a new design for a thermal switch that exploits the temperature dependence of a ferromagnetic material situated between a hot and cold surface. A numerical model is presented which predicts the behavior of the thermal switch. It is shown that with modifications to the physical structure, the device can be tuned to turn on at different heat source temperatures. The time-averaged heat flux and effective conductance compare favorably to existing thermal switch technologies over a range of heat source temperatures. Additionally, it is shown that the contact conductance of the surfaces has a large influence on the device performance.

scholarly journals Large penetration depth of near-field heat flux in hyperbolic media

2014 ◽  
Vol 104 (12) ◽  
pp. 121903 ◽  
Author(s):  
S. Lang ◽  
M. Tschikin ◽  
S.-A. Biehs ◽  
A. Yu. Petrov ◽  
M. Eich
Keyword(s):  
Heat Flux ◽  
Penetration Depth ◽  
Near Field

Near-Field Radiative Heat Transfer Between Mie Resonance-Based Metamaterials Made of Coated Nonmagnetic Particles

2019 ◽  
Author(s):  
Lu Lu ◽  
Jinlin Song ◽  
Kun Zhou ◽  
Qiang Cheng
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Crystals ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Nematic Liquid Crystals ◽  
Near Field ◽  
Core Shell ◽  
Mie Resonance ◽  
Shell Particles

Abstract Near-field radiative heat transfer between Mie resonance-based metamaterials composed of SiC/d-Si (silicon carbide and doped silicon) core/shell particles immersed in aligned nematic liquid crystals are numerically investigated. The metamaterials composed of core/shell particles exhibit superior performances of enhanced heat transfer and obvious modulation effect when compared to that without shell. The underlying mechanism can be explained that the excitation of Fröhlich mode and epsilon-near-zero (ENZ) resonances both contribute to the total heat flux. Modulation of near-field radiative heat transfer can be realized with the host material of aligned nematic liquid crystals. The largest modulation ratio could be achieved as high as 0.45 for metamaterials composed of core/shell SiC/d-Si particles, and the corresponding heat flux is higher than other similar materials such as LiTaO3/GaSb and Ge/LiTaO3. While with the same volume filling fraction, the modulation ratio of that composed of SiC particles is only 0.2. We show that the core/shell nanoparticles dispersed liquid crystals (NDLCs) have a great potential in enhancing the near-field radiative heat transfer in both the p and s polarizations with the radii of 0.65 μm, and Mie-metamaterials are shown for the first time to modulate heat flux within sub-milliseconds.

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