Experimental Exploration of Near-Field Radiative Heat Transfer

Ghashami, Mohammad; Jarzembski, Amun; Lim, Mikyung; Lee, Bong Jae; Park, Keunhan

doi:10.1615/annualrevheattransfer.2020032656

Cited by 15 publications

(6 citation statements)

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“…These conditions make maintaining the nanoscale vacuum gap quite challenging because of structural deformation by thermal stress. 41 Recently, Inoue et al 13 have developed a one-chip NF-TPV device working with an area of 1 mm 2 , a vacuum gap <140 nm, and a temperature difference of ∼900 K. They discussed that an up-scaled device is required to further improve the system efficiency by reducing the conduction and thermal radiation losses. However, it would be challenging to maintain high power density for up-scaled NF-TPV devices because of the inevitable series resistance losses primarily caused by the large photocurrent.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Since the concept of the NF-TPV device was proposed by Whale and Cravalho, there have been only a few groups who have experimentally realized NF-TPV devices, ,,− despite the substantial progress in measuring the near-field radiation. ,− ,− The main factors of experimental difficulty are the essential requirements for a practical high-power-output NF-TPV device: a large heat transfer area and a large temperature difference between the emitter and the PV cell. These conditions make maintaining the nanoscale vacuum gap quite challenging because of structural deformation by thermal stress . Recently, Inoue et al .…”

Section: Resultsmentioning

confidence: 99%

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Thermophotovoltaic Energy Conversion in Far-to-Near-Field Transition Regime

et al. 2022

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Recent experimental studies on near-field thermophotovoltaic energy conversion have mainly focused on improving performance via photon tunneling of evanescent waves. In the sub-micron gap, however, there exist peculiar phenomena induced by the interference of propagating waves, which are seldom observed in the full spectrum radiation due to the massive increase in evanescent modes. Here, we experimentally demonstrate the oscillatory nature of near-field thermophotovoltaic energy conversion in the far-to-near-field transition regime (250−2600 nm), where evanescent and propagating modes are comparable due to the selective spectral response by the photovoltaic cell. Noticeably, we show that the same amount of photocurrent can be generated at different vacuum gaps of 870 and 322 nm, which is 10% larger than the far-field value.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Thermophotovoltaic Energy Conversion in Far-to-Near-Field Transition Regime

et al. 2022

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“…The main factors of experimental difficulty are the essential requirements for a practical high-power-output NF-TPV: a large heat transfer area and a large temperature difference between the emitter and the PV cell. These conditions make maintaining the nanoscale vacuum gap quite challenging because of structural deformation by thermal stress [29]. Recently, it was reported that a one-chip NF-TPV device with an area of 1 mm 2 , a vacuum gap <140 nm, and a temperature difference of ∼900 K had been fabricated [9].…”

Section: Discussionmentioning

confidence: 99%

Thermophotovoltaic energy conversion in far-to-near-field transition regime

Song,

Jang,

Lim

et al. 2021

Preprint

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Recent experimental studies on near-field thermophotovoltaic (TPV) energy conversion have mainly focused on enhancing performance via photon tunneling of evanescent waves. In the submicron gap, however, there exist peculiar phenomena caused by the interference of propagating waves, which is seldom observed due to the dramatic increase of the radiation by evanescent waves in full spectrum range. Here, we experimentally demonstrate the oscillatory nature of near-field TPV energy conversion in the far-to-near-field transition regime (250-2600 nm), where evanescent and propagating modes are comparable due to the selective spectral response by the PV cell.Noticeably, it was possible to produce the same amount of photocurrent at different vacuum gaps of 870 and 322 nm, which is 10% larger than the far-field value. Considering the great challenges in maintaining nanoscale vacuum gap in practical devices, this study suggests an alternative approach to the design of a TPV system that will outperform conventional far-field counterparts.

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“…These waves are strong carriers of electromagnetic energy and are confined on the interfaces. By approaching two materials which support similar SPhPs, a coupling of surface waves could drastically enhance the electromagnetic energy transfer, leading to NFRHT 2 . In this regime, radiative coupling from evanescent waves emitted by both bodies enhances transmitted power by up to a factor 100 at nanometer-scale gaps ( ) compared to the blackbody limit of conventional far-field heat transfer 3 , 4 .…”

Section: Introductionmentioning

confidence: 99%

Toward applications of near-field radiative heat transfer with micro-hotplates

Marconot

Juneau-Fecteau

Fréchette

2021

Sci Rep

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Bringing bodies close together at sub-micron distances can drastically enhance radiative heat transfer, leading to heat fluxes greater than the blackbody limit set by Stefan–Boltzmann law. This effect, known as near-field radiative heat transfer (NFRHT), has wide implications for thermal management in microsystems, as well as technological applications such as direct heat to electricity conversion in thermophotovoltaic cells. Here, we demonstrate NFRHT from microfabricated hotplates made by surface micromachining of $$\hbox {SiO}_2$$ SiO 2 /$$\hbox {SiN}$$ SiN thin films deposited on a sacrificial amorphous Si layer. The sacrificial layer is dry etched to form wide membranes ($${100}\,\upmu \hbox {m} \times {100}\,\upmu \hbox {m}$$ 100 μ m × 100 μ m ) separated from the substrate by nanometric distances. Nickel traces allow both resistive heating and temperature measurement on the micro-hotplates. We report on two samples with measured gaps of $${610}\,\hbox {nm}$$ 610 nm and $${280}\,\hbox {nm}$$ 280 nm . The membranes can be heated up to $${250}\,^{\circ }\hbox {C}$$ 250 ∘ C under vacuum with no mechanical damage. At $${120}\,^{\circ }\hbox {C}$$ 120 ∘ C we observed a 6.4-fold enhancement of radiative heat transfer compared to far-field emission for the smallest gap and a 3.5-fold enhancement for the larger gap. Furthermore, the measured transmitted power exhibits an exponential dependence with respect to gap size, a clear signature of NFRHT. Calculations of photon transmission probabilities indicate that the observed increase in heat transfer can be attributed to near-field coupling by surface phonon-polaritons supported by the $$\hbox {SiO}_2$$ SiO 2 films. The fabrication process presented here, relying solely on well-established surface micromachining technology, is a key step toward integration of NFRHT in industrial applications.

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Experimental Exploration of Near-Field Radiative Heat Transfer

Cited by 15 publications

References 0 publications

Thermophotovoltaic Energy Conversion in Far-to-Near-Field Transition Regime

Thermophotovoltaic Energy Conversion in Far-to-Near-Field Transition Regime

Thermophotovoltaic energy conversion in far-to-near-field transition regime

Toward applications of near-field radiative heat transfer with micro-hotplates

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