Article
Chemistry, Multidisciplinary
Xin-Bao Liu, Shi-Qi Hu, Daqiang Chen, Mengxue Guan, Qing Chen, Sheng Meng
Summary: This study investigates the variation in electron-phonon couplings under laser excitation using monolayer MoS2 as a prototype. Real-time time-dependent density functional theory simulations reveal phonon softening, anisotropic modification of the deformation potential, and enhancement of EPC due to reduced electronic screening and modulated potential energy surfaces by photoexcitation.
Article
Chemistry, Multidisciplinary
Juhong Park, Sanket Bhoyate, Young-Hoon Kim, Young-Min Kim, Young Hee Lee, Patrick Conlin, Kyeongjae Cho, Wonbong Choi
Summary: By studying the high ion conductivity of Li+, Na+, and K+ in 2D MoS2 nanofilm, a new understanding of the formation mechanism of novel ion channels has been revealed. This discovery provides new insights and methods for the preparation of superionic conductivity devices.
Article
Chemistry, Physical
Bingyang Wu, Man Zhou, Dajie Xu, Jiaju Liu, Rongjiang Tang, Ping Zhang
Summary: The interfacial thermal conductance of BP/MoS2 2D van der Waals heterostructures is greatly influenced by temperature and Mo vacancy defects. The presence of Mo vacancy defects shifts the phonon density of states towards lower frequencies and increases the number of low-frequency phonons, leading to nonlocalization features in the low-frequency range. These findings offer theoretical insights for manipulating thermal conductance in devices based on BP/MoS2 vdW heterostructures.
SURFACES AND INTERFACES
(2022)
Article
Multidisciplinary Sciences
Qinshu Li, Fang Liu, Song Hu, Houfu Song, Susu Yang, Hailing Jiang, Tao Wang, Yee Kan Koh, Changying Zhao, Feiyu Kang, Junqiao Wu, Xiaokun Gu, Bo Sun, Xinqiang Wang
Summary: This study reveals that even for materials with similar Debye temperatures, a significant portion of phonons can transport inelastically across interfaces at high temperatures, greatly enhancing the interface thermal conductance. The sharpness of the interface strongly affects the phonon transport process. These findings provide new insights and opportunities for engineering interface thermal conductance in microelectronics materials.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Sanjay Bhakhar, Nashreen F. Patel, Pratik M. Pataniya, Shubham Gupta, G. K. Solanki, Prafulla K. Jha
Summary: Direct vapor phase synthesis technique was used to grow bulk InxMo1-xS2 (x = 0, 0.05, 0.1) with hexagonal structure and P63/mmc space group. Raman spectroscopy was employed to study the electron-phonon interaction in these crystals, observing first order modes A1g and E2g, as well as second order mode b-mode. Temperature dependent Raman spectroscopy revealed peak shifting in the range of -180℃ to 240℃. Energy Dispersive Analysis of X-ray (EDAX) and powder X-ray Diffraction (XRD) confirmed the findings on bulk InxMo1-xS2 (x = 0, 0.05, 0.1).
SURFACES AND INTERFACES
(2023)
Article
Chemistry, Physical
Hengrui Yang, Weitang Li, Jiajun Ren, Zhigang Shuai
Summary: This study proposes a nearly exact method to evaluate the time-dependent current and occupation number in a molecular junction with strong electron-phonon coupling. The oscillation period and amplitude of the current are found to be dependent on the electron-phonon coupling strength and energy level alignment. A new approximation is introduced to explain the bistability phenomenon and steady currents in the strong electron-phonon coupling regime, and comparisons are made with other methods. The entropy of different orderings is also explored, and the thermal Bogoliubov transformation is used for finite-temperature analysis.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Nanoscience & Nanotechnology
Julia E. Greenwald, Joseph Cameron, Neil J. Findlay, Tianren Fu, Suman Gunasekaran, Peter J. Skabara, Latha Venkataraman
Summary: Researchers have successfully created a molecular system where the constructive quantum interference between certain molecular orbitals is suppressed, while the destructive interference between other molecular orbitals is enhanced, leading to highly nonlinear single-molecule circuits. They demonstrated the effectiveness of this strategy using fluorene oligomers containing a central benzothiadiazole unit, achieving a reproducible modulation of the conductance of a 6-nm molecule by more than 10,000 at room temperature.
NATURE NANOTECHNOLOGY
(2021)
Article
Thermodynamics
Xu Huang, Zhixiong Guo
Summary: The study focuses on the thermal dissipation in diamond/GaN heterostructures with different epilayers. It is found that Si3N4 epilayer has the lowest thermal boundary resistance among the three types of diamond/GaN interfaces. Additionally, c-BN is emerging as a promising material for optoelectronic devices due to its diamond-like thermal properties and ability to reduce interfacial TBR in the diamond/c-BN interface.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Materials Science, Multidisciplinary
Alois Arrighi, Elena del Corro, Daniel Navarro Urrios, Marius Vasile Costache, Juan F. Francisco Sierra, Kenji Watanabe, Takashi Taniguchi, Jose A. Garrido, Sergio O. Valenzuela, Clivia M. Sotomayor Torres, Marianna Sledzinska
Summary: State-of-the-art fabrication and characterisation techniques were used to measure the thermal conductivity of suspended, single-crystalline MoS2 and MoS2/hBN heterostructures. The results showed that the heterostructure exhibited a significantly increased thermal conductivity due to the high thermal interface conductance between MoS2 and hBN, as well as the efficient in-plane heat spreading driven by hBN.
Article
Physics, Multidisciplinary
Noga Bashan, Assa Auerbach
Summary: This paper simplifies the Kubo formulas for Hall, transverse thermoelectric, and thermal Hall conductivities into on-shell commutators of degeneracy projected polarizations. These new expressions are computationally economical and can be applied to general Hamiltonians without a gap restriction. The study shows that Hall currents in open boundaries are carried by gapless chiral excitations. The extrapolation of finite lattice calculations to the dc-thermodynamic limit is also demonstrated for a disordered metal.
PHYSICAL REVIEW LETTERS
(2022)
Article
Thermodynamics
Wuli Miao, Moran Wang
Summary: This study investigates thermal transport in metal/semiconductor multilayer films using the coupled electron and phonon Boltzmann transport equations combined with the phonon diffuse mismatch model. The importance of electron-phonon coupling transport and the critical thickness of the metal layer for considering this transport are demonstrated. The research findings provide insight into the manipulation of thermal conductivity in multilayers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Chemistry, Multidisciplinary
Brent Lawson, Percy Zahl, Mark S. Hybertsen, Maria Kamenetska
Summary: Single-molecule circuits with group 8 metallocenes are formed without additional linker groups in scanning tunneling microscope-based break junction measurements. The nature of the gold-pi binding motif and its effect on molecular conductance and persistence characteristics during junction evolution are investigated. The interaction between the cyclopentadienyl rings of the metallocenes and the gold electrodes allows for extended conductance plateaus.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Review
Chemistry, Multidisciplinary
Hoon Kim, Gimin Park, Sungjin Park, Woochul Kim
Summary: This review summarizes recent efforts in manipulating phonon transport in solids by modifying phonon thermal conductivity and conductance. Various strategies for tuning thermal conductivity and conductance are discussed, including impacting phonon group velocity and mean free path.
Article
Chemistry, Physical
Natalya A. A. Zimbovskaya, Abraham Nitzan
Summary: In this study, the effect of chain configuration on phonon heat transport in a single polymer chain is analyzed theoretically based on recent molecular dynamic simulations. It is found that when the chain is strongly compressed and tangled, multiple random bends act as scattering centers for vibrational phonon modes, resulting in diffusive heat transport. As the chain straightens up, the number of scatterers decreases and the heat transport becomes more ballistic. A model of a long atomic chain is introduced to simulate the changes in chain configuration, and the phonon thermal conductance exhibits a threshold-like transition from diffusive to ballistic transport as the scatterers are gradually removed.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Ben Cao, Shufang Ma, Wenliang Wang, Xin Tang, Dou Wang, Weikang Shen, Bocang Qiu, Bingshe Xu, Guoqiang Li
Summary: This study successfully synthesized Mg-doped p-type MoS2/GaN heterojunctions, in which the Mg doping introduced abundant holes, leading to an inverted internal electric field and high responsivity with fast response time. This provides an efficient preparation strategy for the application of nanoelectronic and nano-optoelectronic devices.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Thermodynamics
Rong Xue, Xinyi Lin, Yixiao Ruan, Liang Chen, Yu Hou
Summary: The study shows that the temperature is lower in the region closer to the spray field, with a larger temperature difference near the spray on the test plane. The high uniformity of temperature distribution is obtained after flowing through two elbow pipes. In steady-state cooling, the average temperature gradually increases along the flow direction, with the temperature uniformity in the reverse order.
Article
Materials Science, Multidisciplinary
Xiangru Kong, Wei Luo, Linyang Li, Mina Yoon, Tom Berlijn, Liangbo Liang
Summary: Using ab initio tight-binding approaches, the researchers investigated the Floquet band engineering of transition metal dichalcogenides monolayers under irradiation. They found that light can induce important transitions in the topological phases of these materials.
Article
Thermodynamics
Yu Yang, Chunchen Sheng, Gaoqiao Luo, Shuangtao Chen, Yu Hou, Liang Chen
Summary: This study evaluates three mean-line methods for the design of high-speed turbo-coolers and establishes a coupling model to predict the off-design performance and system size. The results show that the SS-CR approach has a slightly higher expander efficiency at the design point, but the PR approach performs better at low speeds. In terms of system volume, the SS-CR approach is superior to the other two methods. When the cooling capacity is controlled at 2000 W, the SS-CR approach also has a slightly higher expander efficiency compared to the other two methods.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2023)
Article
Thermodynamics
Liang Chen, Jing Fan, Pingtao Zhang, Runfeng Xiao, Yansong Si, Shuangtao Chen, Yu Hou
Summary: This paper investigates a finned tube heat exchanger with dual-side phase change heat transfer to enhance the thermal management of intermittent high-power output electronics. The use of two-phase heat transfer fluid on the tube side significantly increases the heat-charging power and storage effectiveness of LHTES. The study also reveals that the storage effectiveness decreases with the increase of condensation pressure while the mass flow rate of the tube-side fluid has no obvious effect.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Yu Zhang, Pingtao Zhang, Liang Chen, Shuangtao Chen, Yu Hou
Summary: This paper introduces a stacked-plate jet impingement microchannel (SP-JIMC) heat sink with highly-dense micro-fins and numerically investigates its thermal and hydraulic performance using single-phase water as coolant. Comparative analysis with other types of heat sinks demonstrates that the SP-JIMC offers better cooling performance and temperature uniformity. The study also explores the influence of structural parameters on heat transfer characteristics and proposes improvements such as dual-side micro-fins and convex/concave impinged surfaces to further enhance the thermal performance.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Xiaoling Yang, Liang Chen, Zhefeng Wang, Shuangtao Chen, Yu Hou
Summary: Spontaneous condensation process of moist air in a high-speed turbo-expander was investigated experimentally and numerically. A liquid fraction of 0.8% was achieved at the turbo-expander outlet corresponding to a relative humidity of 76.9% at 303.2 K. The nucleation process and droplet distribution in the turbo-expander were studied, and the wetness loss due to condensation mainly occurred in the impeller.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Yang Meng, Liang Chen, Xiaoling Yang, Huaide Yang, Zhiqiang Mao, Shuangtao Chen, Yu Hou
Summary: This paper investigates the desublimation process of CO2 in a cryogenic turbo-expander and identifies the impact of inlet temperature, pressure ratio, and inlet CO2 concentration on wetness loss. The study concludes that the maximum subcooling degree for a cryogenic carbon capture system turbo-expander should be less than 15 K to avoid desublimation and wetness loss.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Xiaoling Yang, Liang Chen, Zhefeng Wang, Shuangtao Chen, Yu Hou
Summary: This paper investigates the characteristics of an open-loop air cycle for room temperature applications and studies the effects of the first stage compression ratio and the expander inlet temperature on the refrigerator performance. A system model is established based on numerical simulation and verified by experiments.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2023)
Article
Thermodynamics
Runfeng Xiao, Yicheng Zhang, Liang Chen, Junxin Wang, Shuangtao Chen, Yu Hou
Summary: This paper conducts simulations of supercritical heat transfer of R134a in horizontal tubes to study the effects of circumferential heat conduction on heat transfer deterioration and explain the abnormal phenomena of higher temperature distribution in non-gravity supercritical flow. The results indicate that heat transfer deterioration is caused by impaired specific heat and heat conduction in the boundary layer, and the subsequent heat transfer recovery is due to enhanced thermal conduction and turbulent convection. A dimensionless parameter called the Biot number is defined to characterize the thermal resistance ratio of circumferential conduction to convective heat transfer. The redistribution of wall temperature caused by circumferential conduction affects supercritical convection in horizontal tubes, and non-gravity supercritical flow may have higher wall temperature when the Biot number is small. The deterioration of the top surface can be significantly alleviated by using a tube with larger wall thickness or thermal conductivity.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Chemistry, Multidisciplinary
Liang Chen, Qi Wang, Yansong Si, Yu Hou
Summary: In this work, a heat sink combining the confined jet impingement with metallic phase change material (PCM) is proposed for the thermal management of millisecond-pulsed heat sources. The heat transfer characteristics of the heat sink and the temperature responses under millisecond heat pulses are analyzed. Results show that the jet impingement with specific parameters can achieve effective cooling, and an appropriate PCM thickness is required for stable phase change cycling.
APPLIED SCIENCES-BASEL
(2023)
Article
Thermodynamics
Kaimiao Zhou, Liang Chen, Shanfeng Li, Kang Zhao, Ze Zhang, Shuangtao Chen, Yu Hou
Summary: Liquid hydrogen is crucial for large-scale hydrogen energy development, and the Claude cycle is commonly used for hydrogen liquefaction. The hydrogen turbo-expander plays an important role in determining the efficiency and reliability of the system. This study uses mean-line design and loss models to develop a hydrogen turbo-expander, and CFD simulations are used to analyze the flow field and loss mechanisms. The results show that the hydrogen turbo-expander has higher passage efficiency compared to the helium expander due to its lower viscosity and smaller losses.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Runfeng Xiao, Pingtao Zhang, Liang Chen, Yu Hou
Summary: The heat transfer deterioration (HTD) of supercritical fluids is crucial for the safe operation of power systems. Current criteria for HTD face difficulties in identifying the working conditions of supercritical fluids. This paper proposes a new definition of HTD and a machine learning-based method to predict HTD in upward vertical tubes with supercritical water and CO2. Eight criteria for HTD were compared and analyzed based on two traditional definitions and the proposed new one. Results showed that the discontinuity of experimental data leads to missing HTD points. Traditional methods achieved accuracy ranging from 55% to 82%. The machine learning-based method demonstrated high prediction accuracy of up to 95% for all three definitions of HTD. The proposed definition and the machine learning method can improve the identification and prediction of HTD in supercritical fluids.
APPLIED THERMAL ENGINEERING
(2023)
Review
Thermodynamics
Xiaoling Yang, Rong Xue, Ning Wang, Zhilong Huang, Haiyang Zhang, Xiufang Liu, Liang Chen, Yu Hou
Summary: Spray cooling with liquid nitrogen has advantages for achieving cryogenic temperature, and the process can be divided into three stages: cavitating flow, spray breakup, and cooling process. This paper summarizes published literatures on these stages. A brief review shows that the correlation between thermodynamic parameters and spray cooling characteristics is not fully understood. Future research should focus on gaining a deeper insight into heat transfer mechanisms and enhancing the application of cryogenic spray.
Article
Thermodynamics
Yang Meng, Yicheng Zhang, Junxin Wang, Shuangtao Chen, Yu Hou, Liang Chen
Summary: This paper proposes a reverse-bootstrap turboexpander-compressor (TEC) scheme for the direct recovery of expansion work into the cooling capacity of small air-separation plants. A mathematical model is established for the codesign and off-design analysis of TEC, which is validated by experimental data. The use of a reverse-bootstrap compressor in the original turboexpander can increase the isentropic coefficient by 12%. The codesign of the turboexpander and the coaxial compressor can further increase the isentropic coefficient by 7.1% under design condition, resulting in an 8.1% improvement in cooling power and a 1.7% reduction in required heating power. The results demonstrate that the proposed reverse-bootstrap TEC with the codesign method is an effective way for energy recovery in small refrigeration systems.
Article
Thermodynamics
Shujian Song, Shuangtao Chen, Xiaocong Zhou, Yihang Zhu, Xihan Zhang, Liang Chen, Yu Hou
Summary: This paper investigates the operating characteristics of a closed-cycle single-stage turbo-refrigerator with a motor-driven turboexpander compressor (MTEC). Test results show that variable-speed operation allows for independent control of the refrigeration temperature and cooling capacity. Advanced exergy analysis suggests that with future component improvement, a higher total exergy efficiency can be expected.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2023)
