Showing papers on "Thermal radiation published in 2015"
TL;DR: In this paper, the effect of thermal radiation on magnetohydrodynamics nanofluid flow between two horizontal rotating plates is studied and the significant effects of Brownian motion and thermophoresis have been included in the model of Nanofluide.
700 citations
TL;DR: This work experimentally demonstrates a visibly transparent thermal blackbody, based on a silica photonic crystal, that can cool structures by thermal radiation to outer space, while preserving the structures’ solar absorption.
Abstract: A solar absorber, under the sun, is heated up by sunlight. In many applications, including solar cells and outdoor structures, the absorption of sunlight is intrinsic for either operational or aesthetic considerations, but the resulting heating is undesirable. Because a solar absorber by necessity faces the sky, it also naturally has radiative access to the coldness of the universe. Therefore, in these applications it would be very attractive to directly use the sky as a heat sink while preserving solar absorption properties. Here we experimentally demonstrate a visibly transparent thermal blackbody, based on a silica photonic crystal. When placed on a silicon absorber under sunlight, such a blackbody preserves or even slightly enhances sunlight absorption, but reduces the temperature of the underlying silicon absorber by as much as 13 °C due to radiative cooling. Our work shows that the concept of radiative cooling can be used in combination with the utilization of sunlight, enabling new technological capabilities.
438 citations
TL;DR: In this article, a three-dimensional flow of couple stress nanofluid in the presence of thermophoresis and Brownian motion effects is analyzed and the energy equation subject to nonlinear thermal radiation is taken into account.
289 citations
TL;DR: In this paper, the authors summarize the basics of fluctuational electrodynamics, a theoretical framework for the study of radiative heat transfer in terms of thermally excited propagating and evanescent electromagnetic waves.
Abstract: Radiative thermal transport via the fluctuating electromagnetic near-field has recently attracted increasing attention due to its fundamental importance and its impact on a range of applications from data storage to thermal management and energy conversion. After a brief historical account of radiative thermal transport, we summarize the basics of fluctuational electrodynamics, a theoretical framework for the study of radiative heat transfer in terms of thermally excited propagating and evanescent electromagnetic waves. Various approaches to modeling near-field thermal transport are briefly discussed, together with key results and proposals for manipulation and utilization of radiative heat flow. Subsequently, we review the experimental advances in the characterization of both near-field heat flow and energy density. We conclude with remarks on the opportunities and challenges for future explorations of radiative heat transfer at the nanoscale.
255 citations
TL;DR: In this paper, the basics of thermal evolution for isolated neutron stars with strong magnetic fields are reviewed, including most relevant thermodynamic and kinetic properties in the stellar core, crust, and blanketing envelopes.
Abstract: Observations of thermal radiation from neutron stars can potentially provide information about the states of supranuclear matter in the interiors of these stars with the aid of the theory of neutron-star thermal evolution. We review the basics of this theory for isolated neutron stars with strong magnetic fields, including most relevant thermodynamic and kinetic properties in the stellar core, crust, and blanketing envelopes.
233 citations
TL;DR: In this article, the authors investigated thermal radiation in a semi annulus enclosure with Ferrohydrodynamic and magnetohydrodynamic (MHD) flow and heat transfer and showed that Nusselt number is an increasing function of Rayleigh number, nanoparticle volume fraction, magnetic number while it is a decreasing function of with Hartmann number and radiation parameter.
Abstract: In this paper, ferrofluid flow and heat transfer in a semi annulus enclosure is investigated considering thermal radiation. The enclosure has a wall with constant heat flux boundary condition. Combined effects of Ferrohydrodynamic (FHD) and magnetohydrodynamic (MHD) are considered. It is assumed that the magnetization of the fluid is varying linearly with temperature and magnetic field intensity. Control Volume based Finite Element Method (CVFEM) is applied to solve the governing equations. The calculations were performed for different governing parameters namely; the Radiation parameter, Rayleigh number, nanoparticle volume fraction, Magnetic number arising from FHD and Hartmann number arising from MHD. Results show that Nusselt number is an increasing function of Rayleigh number, nanoparticle volume fraction, magnetic number while it is a decreasing function of with Hartmann number and radiation parameter.
218 citations
TL;DR: In this paper, an analysis has been carried out for the three dimensional flow of viscous nanofluid in the presence of partial slip and thermal radiation effects, where the flow is induced by a permeable stretching surface.
196 citations
TL;DR: Surprisingly, the interaction of phonons originating from neighboring heat sources enables more efficient diffusive-like heat dissipation, even from nanoscale heat sources much smaller than the dominant phonon mean free paths, suggesting that thermal management in nanosystems including integrated circuits might not be as challenging as previously projected.
Abstract: Understanding thermal transport from nanoscale heat sources is important for a fundamental description of energy flow in materials, as well as for many technological applications including thermal management in nanoelectronics and optoelectronics, thermoelectric devices, nanoenhanced photovoltaics, and nanoparticle-mediated thermal therapies. Thermal transport at the nanoscale is fundamentally different from that at the macroscale and is determined by the distribution of carrier mean free paths and energy dispersion in a material, the length scales of the heat sources, and the distance over which heat is transported. Past work has shown that Fourier’s law for heat conduction dramatically overpredicts the rate of heat dissipation from heat sources with dimensions smaller than the mean free path of the dominant heat-carrying phonons. In this work, we uncover a new regime of nanoscale thermal transport that dominates when the separation between nanoscale heat sources is small compared with the dominant phonon mean free paths. Surprisingly, the interaction of phonons originating from neighboring heat sources enables more efficient diffusive-like heat dissipation, even from nanoscale heat sources much smaller than the dominant phonon mean free paths. This finding suggests that thermal management in nanoscale systems including integrated circuits might not be as challenging as previously projected. Finally, we demonstrate a unique capability to extract differential conductivity as a function of phonon mean free path in materials, allowing the first (to our knowledge) experimental validation of predictions from the recently developed first-principles calculations.
194 citations
TL;DR: In this article, the stagnation point flow of nanofluid with magneto-hydrodynamics (MHD) and thermal radiation effects passed over a stretching sheet has been investigated.
Abstract: Present model is devoted for the stagnation point flow of nanofluid with magneto-hydrodynamics (MHD) and thermal radiation effects passed over a stretching sheet. Moreover, we have considered the combined effects of velocity and thermal slip. Condition of zero normal flux of nanoparticles at the wall for the stretched flow phenomena is yet to be explored in the literature. Convinced partial differential equations of the model are transformed into the system of coupled nonlinear differential equations and then solved numerically. Graphical results are plotted for velocity, temperature and nanoparticle concentration for various values of emerging parameters. Variation of stream lines, skin friction coefficient, local Nusselt and Sherwood number are displayed along with the effective parameters. Final conclusion has been drawn on the basis of both numerical and graphs results.
186 citations
TL;DR: In this paper, the magnetic field dependence of the near-field radiative heat transfer (NFRHT) between two parallel plates is studied and it is shown that when the plates are made of doped semiconductors, the near field thermal radiation can be severely affected by the application of a static magnetic field.
Abstract: We present a comprehensive theoretical study of the magnetic field dependence of the near-field radiative heat transfer (NFRHT) between two parallel plates. We show that when the plates are made of doped semiconductors, the near-field thermal radiation can be severely affected by the application of a static magnetic field. We find that irrespective of its direction, the presence of a magnetic field reduces the radiative heat conductance, and dramatic reductions up to 700% can be found with fields of about 6 T at room temperature. We show that this striking behavior is due to the fact that the magnetic field radically changes the nature of the NFRHT. The field not only affects the electromagnetic surface waves (both plasmons and phonon polaritons) that normally dominate the near-field radiation in doped semiconductors, but it also induces hyperbolic modes that progressively dominate the heat transfer as the field increases. In particular, we show that when the field is perpendicular to the plates, the semiconductors become ideal hyperbolic near-field emitters. More importantly, by changing the magnetic field, the system can be continuously tuned from a situation where the surface waves dominate the heat transfer to a situation where hyperbolic modes completely govern the near-field thermal radiation. We show that this high tunability can be achieved with accessible magnetic fields and very common materials like $n$-doped InSb or Si. Our study paves the way for an active control of NFRHT and it opens the possibility to study unique hyperbolic thermal emitters without the need to resort to complicated metamaterials.
134 citations
TL;DR: In this article, a review of the recent progress on both theoretical and experimental studies of near-field thermal radiation with an emphasis on its potential applications is presented, focusing on tip-plane and plane-plane configurations with various material types.
Abstract: Any materials at temperatures higher than absolute zero emit electromagnetic waves due to the thermal fluctuations of free charges or ions. When two or more bodies at different temperatures are brought sufficiently close to each other with vacuum gap spacing smaller than the characteristic thermal wavelength, near-field radiative heat flux can exceed the far-field blackbody limit, governed by the well-known Stefan-Boltzmann law, by orders of magnitude. This article reviews the recent progress on both theoretical and experimental studies of near-field thermal radiation with an emphasis on its potential applications. Recent theoretical developments are presented, such as near-field radiation of general anisotropic materials and 2D materials, application condition of effective medium theory, and exact numerical methods for dealing with arbitrary particles or periodic nanostructures. Recent experimental achievements are also discussed, focusing on tip–plane and plane–plane configurations with various material...
TL;DR: In this paper, the hydromagnetic boundary layer flow past a moving vertical plate in nanofluids in the presence of a uniform transverse magnetic field and thermal radiation has been carried out.
Abstract: An investigation of the hydromagnetic boundary layer flow past a moving vertical plate in nanofluids in the presence of a uniform transverse magnetic field and thermal radiation has been carried out. Three different types of water-based nanofluids containing copper, aluminum oxide and titanium dioxide are taken into consideration. The governing equations are solved using Laplace transform technique and the solutions are presented in closed form. The numerical values of nanofluid temperature, velocity, the rate of heat transfer and the shear stress at the plate are presented graphically for several values of the pertinent parameters. The present study finds applications in engineering devices.
TL;DR: An atomistic framework based on microscopic Maxwell's equations and lattice dynamics is developed to describe the convergence of these heat transfer modes and the transition from one to the other and the conductance is enhanced up to four times compared with the continuum approach, while avoiding its prediction of divergent conductance at contact.
Abstract: Heat transfer typically occurs by conduction via phonons and radiation via photons, but the distinction between them blurs as surfaces come into contact. Chiloyan et al. study heat transfer between surfaces at sub-nanometre separation and explore the behaviour of phonons as the surfaces approach each other.
TL;DR: In this article, the theoretical influence of buoyancy and thermal radiation on MHD flow over a stretching porous sheet was investigated using similarity solution and then solved using homotopy analysis method (HAM).
Abstract: This paper investigates the theoretical influence of buoyancy and thermal radiation on MHD flow over a stretching porous sheet The model which constituted highly nonlinear governing equations is transformed using similarity solution and then solved using homotopy analysis method (HAM) The analysis is carried out up to the 5th order of approximation and the influences of different physical parameters such as Prandtl number, Grashof number, suction/injection parameter, thermal radiation parameter and heat generation/absorption coefficient and also Hartman number on dimensionless velocity, temperature and the rate of heat transfer are investigated and discussed quantitatively with the aid of graphs Numerical results obtained are compared with the previous results published in the literature and are found to be in good agreement It was found that when the buoyancy parameter and the fluid velocity increase, the thermal boundary layer decreases In case of the thermal radiation, increasing the thermal radiation parameter produces significant increases in the thermal conditions of the fluid temperature which cause more fluid in the boundary layer due to buoyancy effect, causing the velocity in the fluid to increase The hydrodynamic boundary layer and thermal boundary layer thickness increase as a result of increase in radiation
TL;DR: It is found that particle arrays interacting in an idealized Born approximation exhibit both enhancement factors, suggesting the possibility of orders-of-magnitude improvement beyond previous designs and the potential for radiative heat transfer to be comparable to conductive heat transfer through air at room temperature, and significantly greater at higher temperatures.
Abstract: We derive shape-independent limits to the spectral radiative heat transfer rate between two closely spaced bodies, generalizing the concept of a blackbody to the case of near-field energy transfer. Through conservation of energy and reciprocity, we show that each body of susceptibility χ can emit and absorb radiation at enhanced rates bounded by |χ|(2)/Im χ, optimally mediated by near-field photon transfer proportional to 1/d(2) across a separation distance d. Dipole-dipole and dipole-plate structures approach restricted versions of the limit, but common large-area structures do not exhibit the material enhancement factor and thus fall short of the general limit. By contrast, we find that particle arrays interacting in an idealized Born approximation (i.e., neglecting multiple scattering) exhibit both enhancement factors, suggesting the possibility of orders-of-magnitude improvement beyond previous designs and the potential for radiative heat transfer to be comparable to conductive heat transfer through air at room temperature, and significantly greater at higher temperatures.
TL;DR: In this article, a new method to produce electricity from heat called thermoradiative energy conversion is analyzed, which is based on sustaining a difference in the chemical potential for electron populations above and below an energy gap and let this difference drive a current through an electric circuit.
Abstract: A new method to produce electricity from heat called thermoradiative energy conversion is analyzed. The method is based on sustaining a difference in the chemical potential for electron populations above and below an energy gap and let this difference drive a current through an electric circuit. The difference in chemical potential originates from an imbalance in the excitation and de-excitation of electrons across the energy gap. The method has similarities to thermophotovoltaics and conventional photovoltaics. While photovoltaic cells absorb thermal radiation from a body with higher temperature than the cell itself, thermoradiative cells are hot during operation and emit a net outflow of photons to colder surroundings. A thermoradiative cell with an energy gap of 0.25 eV at a temperature of 500 K in surroundings at 300 K is found to have a theoretical efficiency limit of 33.2%. For a high-temperature thermoradiative cell with an energy gap of 0.4 eV, a theoretical efficiency close to 50% is found while the cell produces 1000 W/m2 has a temperature of 1000 K and is placed in surroundings with a temperature of 300 K. Some aspects related to the practical implementation of the concept are discussed and some challenges are addressed. It is, for example, obvious that there is an upper boundary for the temperature under which solid state devices can work properly over time. No conclusions are drawn with regard to such practical boundaries, because the work is aimed at establishing upper limits for ideal thermoradiative devices.
TL;DR: In this article, based on exact formulations including the scattering theory and Green's function method, patterning thin films into 1D and 2D metasurfaces is found to increase the radiative heat flux by more than 1 order of magnitude in a certain range of thicknesses.
Abstract: Evanescent waves induced by thermal fluctuations can tunnel through nanoscale gap spacing, leading to super-Planckian thermal radiation. However, investigations of near-field thermal radiation of macroscopic objects have been limited to simple planar or effectively planar geometries until recently. Based on exact formulations including the scattering theory and Green’s function method, patterning thin films into 1D and 2D metasurfaces is found to increase the radiative heat flux by more than 1 order of magnitude in a certain range of thicknesses. The underlying mechanism of this counterintuitive phenomenon lies in the excitation of hyperbolic modes supporting high local density of states for broad frequency and k-space regimes. The radiative heat flux of a 2D metasurface increases monotonically with the thickness, while the heat flux of a 1D metasurface is not so sensitive to the thickness and is surprisingly higher than that of its 2D counterparts. The stark difference is attributed to the rapid-decay su...
TL;DR: In this article, a two-dimensional stagnation point flow of Jeffrey fluid over an exponentially stretching sheet is studied and the convergence of the series solutions is carefully analyzed for the series solution.
TL;DR: It is observed that near-field thermal energy transfer with thermal extraction can be enhanced by around 1 order of magnitude, compared to the case without thermal extraction.
Abstract: Although blackbody radiation described by Planck's law is commonly regarded as the maximum of thermal radiation, thermal energy transfer in the near-field can exceed the blackbody limit due to the contribution from evanescent waves. Here, we demonstrate experimentally a broadband thermal energy extraction device based on hyperbolic metamaterials that can significantly enhance near-field thermal energy transfer. The thermal extractor made from hyperbolic metamaterials does not absorb or emit any radiation but serves as a transparent pipe guiding the radiative energy from the emitter. At the same gap between an emitter and an absorber, we observe that near-field thermal energy transfer with thermal extraction can be enhanced by around 1 order of magnitude, compared to the case without thermal extraction. The novel thermal extraction scheme has important practical implications in a variety of technologies, e.g., thermophotovoltaic energy conversion, radiative cooling, thermal infrared imaging, and heat assisted magnetic recording.
TL;DR: In this paper, a single layer of graphene sheet is patterned into ribbons and the closed circular dispersion of graphene plasmons is opened to become hyperbolic, leading to broadband singularities of density of states.
Abstract: Excitation of surface plasmons enables super-Planckian thermal radiation far beyond the blackbody limit. By patterning a single layer of graphene sheet into ribbons, the closed circular dispersion of graphene plasmons is opened to become hyperbolic, leading to broadband singularities of density of states. Extremely high-k evanescent waves can now couple with hyperbolic graphene plasmons. Consequently, a giant enhancement of the near-field radiative heat flux, by more than one order of magnitude, is demonstrated in this study using rigorous numerical simulations. The findings may open promising pathways for highly efficient thermal management, energy harvesting, and sub-wavelength thermal imaging.
TL;DR: In this paper, the authors theoretically demonstrate a vacuum thermal switch based on near-field thermal radiation between phase transition materials, i.e., vanadium dioxide (VO2), whose phase changes from insulator to metal at 341 K.
Abstract: In the present study, we theoretically demonstrate a vacuum thermal switch based on near-field thermal radiation between phase transition materials, i.e., vanadium dioxide (VO2), whose phase changes from insulator to metal at 341 K. Strong coupling of surface phonon polaritons between two insulating VO2 plates significantly enhances the near-field heat flux, which on the other hand is greatly reduced when the VO2 emitter becomes metallic, resulting in strong thermal switching effect. Fluctuational electrodynamics incorporated with anisotropic wave propagation predicts more than 80% heat transfer reduction at sub-30-nm vacuum gaps and 50% at vacuum gap of 1 μm. Furthermore, the penetration depth inside the uniaxial VO2 insulator is studied at the vacuum gap of 50 nm, suggesting the possible impact of reduced VO2 thickness on the near-field thermal radiation with thin-film structures. By replacing the bulk VO2 receiver with a thin film of several tens of nanometers, the switching effect is further improved over a broad range of vacuum gaps from 10 nm to 1 μm. Finally, the effect of SiO2 substrate for the thin-film emitter or receiver is also considered to provide insights for future experimental demonstrations. By controlling heat flow with near-field radiative transport, the proposed vacuum thermal switch would find practical applications for energy dissipation in microelectronic devices and for the realization of thermal circuits.
TL;DR: In this article, a comprehensive theoretical study on heat transfer characteristics together with fully developed electromagnetohydrodynamic flow of blood through a capillary, having electrokinetic effects by considering the constant heat flux at the wall is presented.
TL;DR: In this article, the effects of the squeeze number, radiation parameter, Schmidt number, Brownian motion parameter, thermophoretic parameter and Eckert number on flow, heat and mass transfer are considered.
Abstract: In this study, heat and mass transfer characteristic of unsteady nanofluid flow between two parallel plates is investigated considering thermal radiation. Two phase model is considered in order to simulate nanofluid. The basic partial differential equations are reduced to ordinary differential equations which are solved numerically using the fourth-order Runge–Kutta method. The effects of the squeeze number, radiation parameter, Schmidt number, Brownian motion parameter, thermophoretic parameter and Eckert number on flow, heat and mass transfer are considered. Results indicate that concentration boundary-layer thickness increases with increase of Radiation parameter. Also it can be found that Nusselt number has direct relationship with Eckert number, Schmidt number, squeeze parameter and Radiation parameter.
TL;DR: In this paper, the mixed convection flow of non-Newtonian nanofluid over a stretching surface in presence of thermal radiation, heat source/sink and first order chemical reaction is addressed.
Abstract: The present study addresses the mixed convection flow of non-Newtonian nanofluid over a stretching surface in presence of thermal radiation, heat source/sink and first order chemical reaction. Casson fluid model is adopted in the present study. Magnetic field contribution is incorporated in the momentum equation whereas the aspects of nanoparticles are considered in the energy and concentration equations. Convective boundary conditions for both heat and mass transfer are utilized. Similarity transformations are employed to reduce the partial differential equations into ordinary differential equations. Series solutions of the resulting problem are obtained. Impacts of all the physical parameters on the velocity, temperature and concentration fields are analyzed graphically. Numerical values of different involved parameters for local skin friction coefficient, local Nusselt and Sherwood numbers are obtained and discussed.
TL;DR: Rodriguez et al. as mentioned in this paper describe a fluctuating volume-current formulation of electromagnetic fluctuations that extends their recent work on heat exchange and Casimir interactions between arbitrarily shaped homogeneous bodies in inhomogeneous media.
Abstract: We describe a fluctuating volume-current formulation of electromagnetic fluctuations that extends our recent work on heat exchange and Casimir interactions between arbitrarily shaped homogeneous bodies [A. W. Rodriguez, M. T. H. Reid, and S. G. Johnson, Phys. Rev. B 88, 054305 (2013)] to situations involving incandescence and luminescence problems, including thermal radiation, heat transfer, Casimir forces, spontaneous emission, fluorescence, and Raman scattering, in inhomogeneous media. Unlike previous scattering formulations based on field and/or surface unknowns, our work exploits powerful techniques from the volume-integral equation (VIE) method, in which electromagnetic scattering is described in terms of volumetric, current unknowns throughout the bodies. The resulting trace formulas (boxed equations) involve products of well-studied VIE matrices and describe power and momentum transfer between objects with spatially varying material properties and fluctuation characteristics. We demonstrate that thanks to the low-rank properties of the associated matrices, these formulas are susceptible to fast-trace computations based on iterative methods, making practical calculations tractable. We apply our techniques to study thermal radiation, heat transfer, and fluorescence in complicated geometries, checking our method against established techniques best suited for homogeneous bodies as well as applying it to obtain predictions of radiation from complex bodies with spatially varying permittivities and/or temperature profiles.
TL;DR: In this paper, the radiative heat flux between two planar materials respectively made of SiC and SiO2 is calculated by means of fluctuational electrodynamics, and rectification variations with temperature and separation distance are reported.
Abstract: By means of fluctuational electrodynamics, we calculate radiative heat flux between two planar materials respectively made of SiC and SiO2. More specifically, we focus on a first (direct) situation where one of the two materials (for example SiC) is at ambient temperature whereas the second material is at a higher one, then we study a second (reverse) situation where the material temperatures are inverted. When the two fluxes corresponding to the two situations are different, the materials are said to exhibit thermal rectification, a property with potential applications in thermal regulation. Rectification variations with temperature and separation distance are reported here. Calculations are performed using material optical data experimentally determined by Fourier transform emission spectrometry of heated materials between ambient temperature (around 300 K) and 1480 K. It is shown that rectification is much more important in the near-field domain, i.e. at separation distances smaller than the thermal wavelength. In addition, we see that the larger is the temperature difference, the larger is rectification. Large rectification is finally interpreted due to a weakening of the SiC surface polariton when temperature increases, a weakening which affects much less SiO2 resonances.
TL;DR: In this article, the authors investigated the problem of MHD boundary layer flow and heat transfer of an electrically conducting dusty fluid over an unsteady stretching surface through a non-Darcy porous medium.
TL;DR: In this paper, the authors used a rigorous fluctuational electrodynamics approach to predict that ultra-thin films of plasmonic materials can be used to dramatically enhance near-field heat transfer.
Abstract: The properties of thermal radiation exchange between hot and cold objects can be strongly modified if they interact in the near field where electromagnetic coupling occurs across gaps narrower than the dominant wavelength of thermal radiation. Using a rigorous fluctuational electrodynamics approach, we predict that ultra-thin films of plasmonic materials can be used to dramatically enhance near-field heat transfer. The total spectrally integrated film-to-film heat transfer is over an order of magnitude larger than between the same materials in bulk form and also exceeds the levels achievable with polar dielectrics such as SiC. We attribute this enhancement to the significant spectral broadening of radiative heat transfer due to coupling between surface plasmon polaritons (SPPs) on both sides of each thin film. We show that the radiative heat flux spectrum can be further shaped by the choice of the substrate onto which the thin film is deposited. In particular, substrates supporting surface phonon polaritons (SPhP) strongly modify the heat flux spectrum owing to the interactions between SPPs on thin films and SPhPs of the substrate. The use of thin film phase change materials on polar dielectric substrates allows for dynamic switching of the heat flux spectrum between SPP-mediated and SPhP-mediated peaks.
TL;DR: In this paper, a second-dimensional non-Newtonian second-grade fluid is studied under the influence of temperature dependent viscosity and thermal conductivity, and the authors have shown the quantitative effects of emerging dimensionless physical parameters on the velocity, temperature, skin friction and heat transfer rate.
TL;DR: In this paper, it was shown that phase change materials exhibiting a phase transition between a dielectric state and a metallic state are good candidates to perform modulation as well as amplification of radiative thermal flux.
Abstract: We show in this article that phase change materials (PCM) exhibiting a phase transition between a dielectric state and a metallic state are good candidates to perform modulation as well as amplification of radiative thermal flux. We propose a simple situation in plane parallel geometry where a so-called radiative thermal transistor could be achieved. In this configuration, we put a PCM between two blackbodies at different temperatures. We show that the transistor effect can be achieved easily when this material has its critical temperature between the two blackbody temperatures. We also see that the more the material is reflective in the metallic state, the more switching effect is realized, whereas the more PCM transition is stiff in temperature, the more thermal amplification is high. We finally take the example of VO2 that exhibits an insulator-metallic transition at 68 °C. We show that a demonstrator of a radiative transistor could easily be achieved in view of the heat flux levels predicted. Far-fiel...