Pub Date : 2019-03-08DOI: 10.1080/15567265.2019.1588929
Jonathan A Malen
The Ninth U.S.-Japan Joint Seminar on Nanoscale Transport Phenomena was held in Tokyo, Japan from July 2 2017 to July 5 2017 at the KKR Hotel Tokyo. This seminar, held once every three years and al...
{"title":"Report on the Ninth U.S.-Japan Joint Seminar on Nanoscale Transport Phenomena","authors":"Jonathan A Malen","doi":"10.1080/15567265.2019.1588929","DOIUrl":"https://doi.org/10.1080/15567265.2019.1588929","url":null,"abstract":"The Ninth U.S.-Japan Joint Seminar on Nanoscale Transport Phenomena was held in Tokyo, Japan from July 2 2017 to July 5 2017 at the KKR Hotel Tokyo. This seminar, held once every three years and al...","PeriodicalId":49784,"journal":{"name":"Nanoscale and Microscale Thermophysical Engineering","volume":"23 1","pages":"79 - 80"},"PeriodicalIF":4.1,"publicationDate":"2019-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15567265.2019.1588929","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47100565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-02-13DOI: 10.1080/15567265.2019.1578310
Xianglei Liu, Jiadong Shen, Y. Xuan
ABSTRACT Emerging black phosphorene (BP) has unique advantages in mediating near-field thermal radiation due to its strong and tunable in-plane anisotropy, but relative researches are rarely reported in stark contrast to its gained tremendous attention in other fields. Here, we investigate near-field thermal radiation of nanopatterned BP considering different ways of patterning and electronic doping. Appropriate doping increases free carrier density, enabling the transition of BP from dielectrics to hyperbolic materials and the excitation of plasmon resonances. Nanopatterned BP is found to possess a higher radiative transfer rate by as high as 65% compared with plane counterparts due to topological transition of phosphorene ribbon plasmons from quasi-ellipses to quasi-hyperbolas. This work opens alternative routes to mediate and enhance near-field thermal radiation, which has promising applications in efficient thermal management and energy conversion.
{"title":"Near-Field Thermal Radiation of Nanopatterned Black Phosphorene Mediated by Topological Transitions of Phosphorene Plasmons","authors":"Xianglei Liu, Jiadong Shen, Y. Xuan","doi":"10.1080/15567265.2019.1578310","DOIUrl":"https://doi.org/10.1080/15567265.2019.1578310","url":null,"abstract":"ABSTRACT Emerging black phosphorene (BP) has unique advantages in mediating near-field thermal radiation due to its strong and tunable in-plane anisotropy, but relative researches are rarely reported in stark contrast to its gained tremendous attention in other fields. Here, we investigate near-field thermal radiation of nanopatterned BP considering different ways of patterning and electronic doping. Appropriate doping increases free carrier density, enabling the transition of BP from dielectrics to hyperbolic materials and the excitation of plasmon resonances. Nanopatterned BP is found to possess a higher radiative transfer rate by as high as 65% compared with plane counterparts due to topological transition of phosphorene ribbon plasmons from quasi-ellipses to quasi-hyperbolas. This work opens alternative routes to mediate and enhance near-field thermal radiation, which has promising applications in efficient thermal management and energy conversion.","PeriodicalId":49784,"journal":{"name":"Nanoscale and Microscale Thermophysical Engineering","volume":"23 1","pages":"188 - 199"},"PeriodicalIF":4.1,"publicationDate":"2019-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15567265.2019.1578310","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42407253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-02-07DOI: 10.1080/15567265.2019.1572679
Rajath Kantharaj, A. Marconnet
ABSTRACT Lithium-ion batteries (LIBs) are complex, heterogeneous systems with coupled electrochemical and thermal phenomena that lead to elevated temperatures, which, in turn, limit safety, reliability, and performance. Despite years of research, there are still open questions about the electrochemical-thermal phenomena within battery cells. This article highlights recent advances in thermal characterization and modeling of LIBs with an emphasis on the multi-scale aspect of battery systems: from the microscale electrode components to the macroscale battery packs. Both heat generation and thermal properties (thermal conductivity and specific heat capacity) are impacted by battery capacity, charge/discharge rate, ambient conditions, and the underlying microstructure. Understanding thermal phenomena and designing batteries to prevent thermal runaway requires multiscale efforts from the microstructure of the electrodes to the overall system behavior. Experimental efforts have focused on both property and performance characterization, as well as development of new battery chemistries for improved performance and new designs for improved thermal management. Past numerical modeling work ranges from computationally efficient lumped approaches to high fidelity microstructural finite element models. Ultimately, coupled electrochemical-thermal investigations (both numerical and experimental) are required to further improve the performance and reliability of batteries, and to prevent thermal runaway. This perspective article provides insight into directions to improve these approaches with the goal of informing design of batteries with improved performance, safety, and reliability.
{"title":"Heat Generation and Thermal Transport in Lithium-Ion Batteries: A Scale-Bridging Perspective","authors":"Rajath Kantharaj, A. Marconnet","doi":"10.1080/15567265.2019.1572679","DOIUrl":"https://doi.org/10.1080/15567265.2019.1572679","url":null,"abstract":"ABSTRACT Lithium-ion batteries (LIBs) are complex, heterogeneous systems with coupled electrochemical and thermal phenomena that lead to elevated temperatures, which, in turn, limit safety, reliability, and performance. Despite years of research, there are still open questions about the electrochemical-thermal phenomena within battery cells. This article highlights recent advances in thermal characterization and modeling of LIBs with an emphasis on the multi-scale aspect of battery systems: from the microscale electrode components to the macroscale battery packs. Both heat generation and thermal properties (thermal conductivity and specific heat capacity) are impacted by battery capacity, charge/discharge rate, ambient conditions, and the underlying microstructure. Understanding thermal phenomena and designing batteries to prevent thermal runaway requires multiscale efforts from the microstructure of the electrodes to the overall system behavior. Experimental efforts have focused on both property and performance characterization, as well as development of new battery chemistries for improved performance and new designs for improved thermal management. Past numerical modeling work ranges from computationally efficient lumped approaches to high fidelity microstructural finite element models. Ultimately, coupled electrochemical-thermal investigations (both numerical and experimental) are required to further improve the performance and reliability of batteries, and to prevent thermal runaway. This perspective article provides insight into directions to improve these approaches with the goal of informing design of batteries with improved performance, safety, and reliability.","PeriodicalId":49784,"journal":{"name":"Nanoscale and Microscale Thermophysical Engineering","volume":"23 1","pages":"128 - 156"},"PeriodicalIF":4.1,"publicationDate":"2019-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15567265.2019.1572679","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43442699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-24DOI: 10.1080/15567265.2019.1576816
S. Ju, J. Shiomi
ABSTRACT With the advances in materials and integration of electronics and thermoelectrics, the demand for novel crystalline materials with ultimate high/low thermal conductivity is increasing. However, search for optimal thermal materials is a challenge due to the tremendous degrees of freedom in the composition and structure of crystal compounds and nanostructures, and thus empirical search would be exhausting. Materials informatics, which combines the simulation/experiment with machine learning, is now gaining great attention as a tool to accelerate the search of novel thermal materials. In this review, we discuss recent progress in developing materials informatics (MI) for heat transport: the exploration of crystals with high/low-thermal conductivity via high-throughput screening, and nanostructure design for high/low-thermal conductance using the Bayesian optimization and Monte Carlo tree search. The progresses show that the MI methods are useful for designing thermal functional materials. We end by addressing the remaining issues and challenges for further development.
{"title":"Materials Informatics for Heat Transfer: Recent Progresses and Perspectives","authors":"S. Ju, J. Shiomi","doi":"10.1080/15567265.2019.1576816","DOIUrl":"https://doi.org/10.1080/15567265.2019.1576816","url":null,"abstract":"ABSTRACT With the advances in materials and integration of electronics and thermoelectrics, the demand for novel crystalline materials with ultimate high/low thermal conductivity is increasing. However, search for optimal thermal materials is a challenge due to the tremendous degrees of freedom in the composition and structure of crystal compounds and nanostructures, and thus empirical search would be exhausting. Materials informatics, which combines the simulation/experiment with machine learning, is now gaining great attention as a tool to accelerate the search of novel thermal materials. In this review, we discuss recent progress in developing materials informatics (MI) for heat transport: the exploration of crystals with high/low-thermal conductivity via high-throughput screening, and nanostructure design for high/low-thermal conductance using the Bayesian optimization and Monte Carlo tree search. The progresses show that the MI methods are useful for designing thermal functional materials. We end by addressing the remaining issues and challenges for further development.","PeriodicalId":49784,"journal":{"name":"Nanoscale and Microscale Thermophysical Engineering","volume":"23 1","pages":"157 - 172"},"PeriodicalIF":4.1,"publicationDate":"2019-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15567265.2019.1576816","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42402977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT EuBiSe3, a narrow-band-gap semiconductor, is synthesized by introducing the rare earth element Eu into Bi2Se3. It can be a potential thermoelectric material due to the relatively complex crystal structure and large effective mass. In this study, the thermoelectric properties of a EuBiSe3 fiber with a diameter of 167 μm have been characterized systematically for the first time from 80 to 290 K by applying our developed T-type method, including thermal conductivity, electrical conductivity and Seebeck coefficient. The thermal conductivity decreases from 1.08 to 0.88 W m−1 K−1 dominated by three-phonon Umklapp scattering and then increases to 1.20 W m−1 K−1 as the temperature increases to 290 K. The electrical conductivity varies from 4209 to 5240 S m−1 in the studied temperature range. The absolute Seebeck coefficient increases slightly to 204 µVK−1 with the increase of temperature. The highest value of the determined dimensionless figure of merit ZT is 0.05, obtained at 290 K.
摘要通过在Bi2Se3中引入稀土元素Eu，合成了窄带隙半导体EuBiSe3。由于其晶体结构相对复杂，有效质量大，有可能成为一种潜在的热电材料。在本研究中，首次采用t型方法系统表征了直径为167 μm的EuBiSe3纤维在80 ~ 290 K范围内的热电性能，包括导热系数、电导率和塞贝克系数。热导率在三声子Umklapp散射作用下从1.08下降到0.88 W m−1 K−1，随着温度升高到290 K，热导率增加到1.20 W m−1 K−1。在所研究的温度范围内，电导率为4209 ~ 5240 S m−1。随着温度的升高，绝对塞贝克系数略有增加，达到204µVK−1。所得无因次值ZT在290 K时的最大值为0.05。
{"title":"Thermoelectric Properties of Single Crystal EuBiSe3 Fiber","authors":"Xiuqi Wang, Shaoyi Shi, Xin Qi, Dong Wu, Weigang Ma, Xing Zhang","doi":"10.1080/15567265.2019.1566937","DOIUrl":"https://doi.org/10.1080/15567265.2019.1566937","url":null,"abstract":"ABSTRACT EuBiSe3, a narrow-band-gap semiconductor, is synthesized by introducing the rare earth element Eu into Bi2Se3. It can be a potential thermoelectric material due to the relatively complex crystal structure and large effective mass. In this study, the thermoelectric properties of a EuBiSe3 fiber with a diameter of 167 μm have been characterized systematically for the first time from 80 to 290 K by applying our developed T-type method, including thermal conductivity, electrical conductivity and Seebeck coefficient. The thermal conductivity decreases from 1.08 to 0.88 W m−1 K−1 dominated by three-phonon Umklapp scattering and then increases to 1.20 W m−1 K−1 as the temperature increases to 290 K. The electrical conductivity varies from 4209 to 5240 S m−1 in the studied temperature range. The absolute Seebeck coefficient increases slightly to 204 µVK−1 with the increase of temperature. The highest value of the determined dimensionless figure of merit ZT is 0.05, obtained at 290 K.","PeriodicalId":49784,"journal":{"name":"Nanoscale and Microscale Thermophysical Engineering","volume":"23 1","pages":"200 - 210"},"PeriodicalIF":4.1,"publicationDate":"2019-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15567265.2019.1566937","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43919835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-02DOI: 10.1080/15567265.2019.1567633
Yi Zhao, Cilong Yu, Wenjing Zhang
ABSTRACT A one-dimensional periodic microstructure was presented for an ultrabroadband near-perfect absorber for thermal radiation. The microstructure comprised a curved periodic stack of tungsten (15 nm) and polymethylpentene (TPX) (35 nm) with 20 layers deposited on a half-cylindrical cavity fabricated on a tungsten substrate. Visible to midinfrared regions (200 nm to 10.9 μm) allow an average measured light absorptivity of approximately 90% for transverse magnetic polarized waves at normal incidence; this property is insensitive to polar angle even when the incident angle is 80°. These superior performances were primarily attributed to intrinsic bandgap absorption in tungsten, excitation of SPPs at the air/W interface, and the resonance of the slow-light effect and its higher-order modes. Furthermore, the spectrum range of near-perfect absorption could be tuned by adjusting the center half-cylindrical shell radius, total pair number and dielectric permittivity. Moreover, the imperfection tolerance of the proposed system was studied by varying the filling ratio of metal in a periodic shell. This work may provide new guidelines for designing metamaterials absorbers that can obtain highly enhanced absorption over an ultrabroadband and in a wide range of angle of incidence.
{"title":"Ultrabroadband Near-perfect Anisotropic Metamaterial Absorber Based on a Curved Periodic W/TPX Stack","authors":"Yi Zhao, Cilong Yu, Wenjing Zhang","doi":"10.1080/15567265.2019.1567633","DOIUrl":"https://doi.org/10.1080/15567265.2019.1567633","url":null,"abstract":"ABSTRACT A one-dimensional periodic microstructure was presented for an ultrabroadband near-perfect absorber for thermal radiation. The microstructure comprised a curved periodic stack of tungsten (15 nm) and polymethylpentene (TPX) (35 nm) with 20 layers deposited on a half-cylindrical cavity fabricated on a tungsten substrate. Visible to midinfrared regions (200 nm to 10.9 μm) allow an average measured light absorptivity of approximately 90% for transverse magnetic polarized waves at normal incidence; this property is insensitive to polar angle even when the incident angle is 80°. These superior performances were primarily attributed to intrinsic bandgap absorption in tungsten, excitation of SPPs at the air/W interface, and the resonance of the slow-light effect and its higher-order modes. Furthermore, the spectrum range of near-perfect absorption could be tuned by adjusting the center half-cylindrical shell radius, total pair number and dielectric permittivity. Moreover, the imperfection tolerance of the proposed system was studied by varying the filling ratio of metal in a periodic shell. This work may provide new guidelines for designing metamaterials absorbers that can obtain highly enhanced absorption over an ultrabroadband and in a wide range of angle of incidence.","PeriodicalId":49784,"journal":{"name":"Nanoscale and Microscale Thermophysical Engineering","volume":"23 1","pages":"67 - 78"},"PeriodicalIF":4.1,"publicationDate":"2019-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15567265.2019.1567633","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49160244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-31DOI: 10.1080/15567265.2018.1561771
I. Hsieh, Mei-Jiau Huang
ABSTRACT The thermal boundary resistances (TBRs) of twin boundaries occurring at three different atomic layers (Te1, Bi, and Te2) of bismuth telluride (Bi2Te3) are investigated in use of the non-equilibrium molecular dynamics (NEMD) simulation method. The simulation results show that among all, the Te1-twin boundaries bring about a lowest interfacial energy corresponding to a most stable system, which explains why this type of twin boundaries is mostly often observed in the laboratory; the Te2-twin boundaries on the other hand possess a largest interfacial energy, resulting in a least stable system. The order in magnitude of the TBRs associated with these three types of twin boundaries is Te2-twin > Bi-twin > Te1-twin. Moreover, the TBR associated with a pair of twin boundaries separated by a distance of 4 unit cell (UC) is found to be about twice as large as that of a single twin boundary of the same type. It implies that the mutual coupling, which causes an increase in TBRs, may be ignored and the effect of twin boundaries may be counted individually as long as the separation distance is larger than 4 UC.
{"title":"An Investigation into the Thermal Boundary Resistance Associated with the Twin Boundary in Bismuth Telluride","authors":"I. Hsieh, Mei-Jiau Huang","doi":"10.1080/15567265.2018.1561771","DOIUrl":"https://doi.org/10.1080/15567265.2018.1561771","url":null,"abstract":"ABSTRACT The thermal boundary resistances (TBRs) of twin boundaries occurring at three different atomic layers (Te1, Bi, and Te2) of bismuth telluride (Bi2Te3) are investigated in use of the non-equilibrium molecular dynamics (NEMD) simulation method. The simulation results show that among all, the Te1-twin boundaries bring about a lowest interfacial energy corresponding to a most stable system, which explains why this type of twin boundaries is mostly often observed in the laboratory; the Te2-twin boundaries on the other hand possess a largest interfacial energy, resulting in a least stable system. The order in magnitude of the TBRs associated with these three types of twin boundaries is Te2-twin > Bi-twin > Te1-twin. Moreover, the TBR associated with a pair of twin boundaries separated by a distance of 4 unit cell (UC) is found to be about twice as large as that of a single twin boundary of the same type. It implies that the mutual coupling, which causes an increase in TBRs, may be ignored and the effect of twin boundaries may be counted individually as long as the separation distance is larger than 4 UC.","PeriodicalId":49784,"journal":{"name":"Nanoscale and Microscale Thermophysical Engineering","volume":"23 1","pages":"36 - 47"},"PeriodicalIF":4.1,"publicationDate":"2018-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15567265.2018.1561771","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42930475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-16DOI: 10.1080/15567265.2018.1519004
F. DeAngelis, M. Muraleedharan, J. Moon, H. Seyf, A. Minnich, A. McGaughey, A. Henry
ABSTRACT We review the status of research on thermal/phonon transport in disordered materials. The term disordered materials is used here to encompass both structural and compositional disorder. It includes structural deviations ranging from an ideal crystal with disordered arrangements of defects all the way to fully amorphous materials, as well as crystals with impurities up through multi-component random alloys. Both types of disorder affect phonons by breaking the symmetry of an idealized crystal and changing their character/mode shapes. These effects have important implications with regard to phonon–phonon interactions, phonon transport and phonon interactions with other quantum particles, which are being actively investigated. Herein, we synthesize the current theoretical understanding, identify the aspects of the problem that require more work, and pose open questions. Abbreviations: BTE: Boltzmann transport equation; DFT: Density functional theory; EPP: Eigenvector periodicity parameter; FAFDTR: Fiber-aligned frequency domain thermoreflectance; GK: Green–Kubo; GKMA: Green–Kubo modal analysis; HCACF: Heat current autocorrelation function; IXS: Inelastic X-ray scattering; LD: Lattice dynamics; LJ: Lennard–Jones; MD: Molecular dynamics; MFP: Mean free path; NEMD: Non-equilibrium molecular dynamics; NMD: Normal-mode dynamics; PDL: Propagon, diffuson, locon; PGM: Phonon gas model; PR: Participation ratio; SCLD: Supercell lattice dynamics; SED: Spectral energy density; TDTR: Time-domain thermoreflectance; VCA: Virtual crystal approximation;
{"title":"Thermal Transport in Disordered Materials","authors":"F. DeAngelis, M. Muraleedharan, J. Moon, H. Seyf, A. Minnich, A. McGaughey, A. Henry","doi":"10.1080/15567265.2018.1519004","DOIUrl":"https://doi.org/10.1080/15567265.2018.1519004","url":null,"abstract":"ABSTRACT We review the status of research on thermal/phonon transport in disordered materials. The term disordered materials is used here to encompass both structural and compositional disorder. It includes structural deviations ranging from an ideal crystal with disordered arrangements of defects all the way to fully amorphous materials, as well as crystals with impurities up through multi-component random alloys. Both types of disorder affect phonons by breaking the symmetry of an idealized crystal and changing their character/mode shapes. These effects have important implications with regard to phonon–phonon interactions, phonon transport and phonon interactions with other quantum particles, which are being actively investigated. Herein, we synthesize the current theoretical understanding, identify the aspects of the problem that require more work, and pose open questions. Abbreviations: BTE: Boltzmann transport equation; DFT: Density functional theory; EPP: Eigenvector periodicity parameter; FAFDTR: Fiber-aligned frequency domain thermoreflectance; GK: Green–Kubo; GKMA: Green–Kubo modal analysis; HCACF: Heat current autocorrelation function; IXS: Inelastic X-ray scattering; LD: Lattice dynamics; LJ: Lennard–Jones; MD: Molecular dynamics; MFP: Mean free path; NEMD: Non-equilibrium molecular dynamics; NMD: Normal-mode dynamics; PDL: Propagon, diffuson, locon; PGM: Phonon gas model; PR: Participation ratio; SCLD: Supercell lattice dynamics; SED: Spectral energy density; TDTR: Time-domain thermoreflectance; VCA: Virtual crystal approximation;","PeriodicalId":49784,"journal":{"name":"Nanoscale and Microscale Thermophysical Engineering","volume":"23 1","pages":"116 - 81"},"PeriodicalIF":4.1,"publicationDate":"2018-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15567265.2018.1519004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49052048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-11DOI: 10.1080/15567265.2019.1575497
Sangyeop Lee, Xun Li, Ruiqiang Guo
ABSTRACT Phonons in graphitic materials exhibit strong normal scattering (N-scattering) compared to umklapp scattering (U-scattering). The strong N-scattering cause collective phonon flow, unlike the relatively common cases where U-scattering is dominant. If graphitic materials have finite size and contact with hot and cold reservoirs emitting phonons with non-collective distribution, N-scattering change the non-collective phonon flow to the collective phonon flow near the interface between graphitic material and a heat reservoir. We study the thermal resistance by N-scattering during the transition between non-collective and collective phonon flows. Our Monte Carlo solution of Peierls-Boltzmann transport equation shows that the N-scattering in graphitic materials reduce heat flux from the ballistic case by around 15%, 30%, and 40% at 100, 200, and 300 K, respectively. This is significantly larger than ~ 5% reduction of Debye crystal with similar Debye temperature (~2300 K). We associate the large reduction of heat flux by N-scattering with the non-linear dispersion and multiple phonon branches with different group velocities of graphitic materials.
{"title":"Thermal Resistance by Transition Between Collective and Non-Collective Phonon Flows in Graphitic Materials","authors":"Sangyeop Lee, Xun Li, Ruiqiang Guo","doi":"10.1080/15567265.2019.1575497","DOIUrl":"https://doi.org/10.1080/15567265.2019.1575497","url":null,"abstract":"ABSTRACT Phonons in graphitic materials exhibit strong normal scattering (N-scattering) compared to umklapp scattering (U-scattering). The strong N-scattering cause collective phonon flow, unlike the relatively common cases where U-scattering is dominant. If graphitic materials have finite size and contact with hot and cold reservoirs emitting phonons with non-collective distribution, N-scattering change the non-collective phonon flow to the collective phonon flow near the interface between graphitic material and a heat reservoir. We study the thermal resistance by N-scattering during the transition between non-collective and collective phonon flows. Our Monte Carlo solution of Peierls-Boltzmann transport equation shows that the N-scattering in graphitic materials reduce heat flux from the ballistic case by around 15%, 30%, and 40% at 100, 200, and 300 K, respectively. This is significantly larger than ~ 5% reduction of Debye crystal with similar Debye temperature (~2300 K). We associate the large reduction of heat flux by N-scattering with the non-linear dispersion and multiple phonon branches with different group velocities of graphitic materials.","PeriodicalId":49784,"journal":{"name":"Nanoscale and Microscale Thermophysical Engineering","volume":"23 1","pages":"247 - 258"},"PeriodicalIF":4.1,"publicationDate":"2018-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/15567265.2019.1575497","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44276243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-27DOI: 10.1080/15567265.2018.1551448
S. Misyura
ABSTRACT Evaporation and heat transfer of layers of aqueous salt solutions have been studied. The behavior of salt solutions is compared for a smooth and micro-structured wall with a rectangular profile. The evaporation rate of the salt solution on the structured wall is 20–30% higher than on the smooth one at high salt concentration. Previously, it was thought that the heat transfer for solutions can be calculated for thin layers and films without taking into account the natural convection in liquid. In this paper, the liquid free convection is shown to play a key role. A simple model linking the solutal and the thermal Marangoni numbers and the Peclet number with free convection of the liquid on a hot structured wall is considered. For correct simulation of the non-isothermal heat and mass transfer, it is necessary to take into account local characteristics of thermal and velocity fields inside a layer of the salt solution, as well as to determine the average characteristic scales of circulation into the liquid. To simplify the analysis it is possible to effectively consider four types of characteristic convective scales, the role of which depends on the thickness and diameter of the solution layer, as well as on the wall temperature. The strong influence of free convection in a thin layer of the solution is extremely important for accurate modeling of a wide range of modern technologies. Intensification of heat transfer and evaporation due to the use of a structured wall can be applied in heat exchangers, to improve efficiency in desalination of water, in energy technologies (e.g., in heat absorption pumps), as well as in chemical technologies.
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