Optimization of the rectification factor of radiative thermal diodes based on two phase-change materials
Introduction
Thermal diodes transporting heat in a preferred direction and blocking it in the opposite one have recently attracted significant attention due to their promising applications on heat control and nanoscale thermal modulation [1], [2], [3], [4]. The unusual behavior of thermal diodes have paved the way for controlling the rate of heat flows in a similar way as is done with their electric current counterparts in modern electronic devices. Over the last few years, the rectification effect has been theoretically studied through thermal diodes driven by electrons [5], photons [6], [7], [8], [9], [10], phonons [3], [4], [11], [12], [13], [17], [18], quantum dots, hybrid quantum structures [14], [15], [16], and nanoporous silicon devices [17]. The experimental study of the diode effect, on the other hand, was done by using quantum dots [19], carbon nanotubes structures [20], graphene nanoribbons [21], nanoporous graphene [22], solid-liquid phase change thermal diodes [23], as well as electrostatic [24] and bulk oxide materials [25].
One of the main methods to rectify heat flows consists of using phase-change materials (PCMs), whose optical, electrical and thermal properties significantly change with temperature, in a relatively narrow interval of temperatures. These changes are generated by the correlated interactions of phonons and electrons inside a PCM [26] and can be applied for developing thermal memories [27], thermal memristors [28], [29], optical switching [30], thermal rectifier [31], [32], thermal switch [33] radiative thermal diodes [34], [35], [36], [37], and radiative thermal transistors [38], [39] operating in both the near- and far-field regimes [26], [34], [38], [40]. This wide variety of promising applications has motivated the interest on PCMs, such as vanadium dioxide (VO2), nitinol, Ge2Sb2Te5 (GST), whose emissivities can be thermally driven [26], [34], [40]. These three thermochromic materials have recently attracted great attention in both experimental and theoretical studies due to their metal-insulator transition (MIT) at temperatures near room temperature. For example, the emissivities of GST and VO2 undergo the MIT within the temperature ranges of 420 K < T < 430 K and 340 K < T < 345 K, respectively [41]. The fact that the MIT of VO2 occurs in a temperature interval of only 5 K has motivated its application as one of the terminals of a radiative thermal diode [34], whose rectification factor can be as high as 90%. This significant rectification is more than four times the typical ones obtained without PCMs [36], which indicates the great potential of these materials to rectify heat flows.
Taking into account that a thermal diode is composed of two terminals and that two PCMs provide more degrees of freedom than a single PCM to tailor the heat transport between them, the rectification factor of radiative thermal diodes is expected to be optimized by the combined effect of two PCMs, as was proposed for conductive thermal diodes [42], [43]. For instance, Yang et al. [44], determined rectification factors up to 50% and 80% for a conductive thermal diode made up of two PCMs, whose thermal conductivities vary linearly and quadratically with temperature, respectively. Furthermore, a high rectification ratio of 147% was also obtained by Kang et al. [45] for a conductive thermal diode operating with two PCMs. These rectification factors are higher than the ones obtained for conductive thermal diodes base on a single PCM [42], [43]. This fact indicates that two PCMs could also be applied to enhance the rectification factor of radiative thermal diodes, which is not reported in the literature yet, to the best of our knowledge
The goal of this work is to theoretically optimize the thermal rectification effect of plane, cylindrical and spherical radiative thermal diodes based on two PCMs. This is comparatively done by considering the temperature dependence of the emissivities of each PCM within their MITs. Simple analytical expressions are derived and analyzed for the optimal rectification factors of these three diodes supporting thermal radiation generated by a relatively narrow temperature difference between their terminals. Our calculations show that the rectification factor can be raised significantly by using two PCMs instead of the single PCM.
Section snippets
Theoretical modeling
Let us consider two semi-infinite plates consisting of GST and VO2 exchanging heat through radiation as a result of their temperature difference as illustrated in Fig. 1(a) and (b), respectively. The two plates are separated by a vacuum gap of thickness d much longer than the involved thermal wavelengths to ensure the far-field regime of heat transport. In the forward configuration [Fig. 1(a)], the heat flow qF flows from GST to VO2, while in the backward one [Fig. 1(b)], the heat flow
Results and discussions
Fig. 4 (a) shows the heat flows exchanged by the terminals of a plane diode operating in the forward and backward configurations, as functions of the temperature Th. Note that both heat flows qF and qB exhibit a nearly linear increase with Th and change of slope at temperatures around the transition temperatures (Th ≈ T0n with ) of the PCMs emissivities. According to Fig. 3, the transition of qB at K is related to the MIT of VO2, while that of qF at K is driven by the MIT
Conclusion
We have theoretically analyzed and optimized the rectification factors of plane, cylindrical and spherical radiative thermal diodes with terminals made up of two phase-change materials. This has been done by deriving analytical expressions for the optimal rectification factors of these three diodes. It has been shown that combined effect of two phase-change materials along with the geometry of the thermal diode has a significant impact on its rectification factor. Optimal rectification factors
Declaration of Competing Interest
Authors declare that there is no conflict of interest among them.
References (50)
- et al.
A review of thermal rectification observations and models in solid materials
Int. J. Therm. Sci.
(2011) - et al.
Thermal rectification enabled by near-field radiative heat transfer between intrinsic silicon and a dissimilar material
Nanosc. Microsc. Therm.
(2013) - et al.
Thermal rectification assisted by lattice transitions
Int. J. Therm. Sci.
(2014) - et al.
Theoretical analysis of thermal rectification in a bulk si/nanoporous si device
Phys. Lett. A
(2012) - et al.
Tunable thermal rectification in silicon-functionalized graphene nanoribbons by molecular dynamics simulation
Int. J. Therm. Sci.
(2015) - et al.
Thermal conductivity and thermal rectification of nanoporous graphene: a molecular dynamics simulation
Int. J. Heat Mass Trans.
(2020) - et al.
Numerical and experimental study of the thermal rectification of a solid-liquid phase change thermal diode
Int. J. Heat Mass Trans.
(2020) - et al.
A phase-change thermal diode using electrostatic-induced coalescing-jumping droplets
Int. J. Heat Mass Trans.
(2019) - et al.
On the optimization of heat rectification in graded materials
Int. J. Heat Mass Trans.
(2019) - et al.
Thermal rectification based on thermochromic materials
Int. J. Heat Mass Trans.
(2013)
Thermal switch and thermal rectification enabled by near-field radiative heat transfer between three slabs
Int. J. Heat Mass Trans.
Maximal rectification ratios for idealized bi-segment thermal rectifiers
Sci. Rep.
Colloquium: phononics: manipulating heat flow with electronic analogs and beyond
Rev. Mod. Phys.
Thermal diode: rectification of heat flux
Phys. Rev. Lett.
Single mode heat rectifier: controlling energy flow between electronic conductors
Phys. Rev. Lett.
Thermal rectification through vacuum
Phys. Rev. Lett.
Rectification of evanescent heat transfer between dielectric-coated and uncoated silicon carbide plates
J. Appl. Phys.
Near-field radiative transfer based thermal rectification using doped silicon
Appl. Phys. Lett.
Radiative thermal rectification between sic and sio 2
Opt. Express
Thermal conduction and rectification in few-layer graphene y junctions
Nanoscale
Sufficient conditions for thermal rectification in general graded materials
Phys. Rev. E
Quantum thermal diode based on two interacting spinlike systems under different excitations
Phys. Rev. E
Sufficient conditions for thermal rectification in hybrid quantum structures
Phys. Rev. Lett.
Thermal rectification in nonlinear quantum circuits
Phys. Rev. B
Thermal rectifier efficiency of various bulk–nanoporous silicon devices
Int. J. Heat Mass Trans.
Cited by (17)
Isotope engineering of near-field radiative thermal diodes
2023, International Journal of Heat and Mass TransferProgress in thermal rectification due to heat conduction in micro/nano solids
2023, Materials Today PhysicsCitation Excerpt :Thermal rectification technology is helpful to realize effective control of heat conduction and can be applied in various fields. Through the study of thermal rectification phenomenon, the development of thermal rectification technology has been well applied in the design of innovative device, such as thermal transistor [20,64], thermoelectric device [65], thermal diode [66–68] and thermal logic device [69,70]. Thermal diode refers to the thermal device with different heat transfer abilities at the same temperature difference so that heat flow can be rectified, and thermal rectifier is similar to thermal diode.
Thermal rectification of solid-liquid phase change thermal diode under the effect of supercooling
2021, International Journal of Thermal SciencesCitation Excerpt :Kang et al. [35] proposed a general theoretical model for conductive SS-PCTD based on one-dimensional heat conduction equation, which can estimate the heat flux and thermal rectification ratio of the SS-PCTDs composed of different materials. Moreover, Kasali et al. [36] theoretically studied the thermal rectification of radiative SS-PCTD in shapes of plane, cylinder and sphere, finding that spherical radiative SS-PCTD can reach a larger thermal rectification ratio. By contrast, the research on solid-liquid PCTDs (SL-PCTDs) is in infant stage, and the dominant physical mechanism in solid-liquid PCMs (SL-PCMs) is elusive.
Thermophysical Properties of Metal-Insulator Transition Materials During Phase Transition for Thermal Control Devices
2021, International Journal of Heat and Mass TransferCitation Excerpt :For instance, Cui et al. developed a film using VO2 nanoparticles as a dimming window for a house [1]. Kasali et al. reported radiative thermal diodes with two phase-change materials such as Ge2Sb2Te5 and VO2 [2]. Moreover, Tachikawa et al. studied the application of La0.775Sr0.115Ca0.11MnO3 as a variable emittance radiator for spacecraft [3-6].