Article
Chemistry, Physical
Artyom D. Glova, Victor M. Nazarychev, Sergey Larin, Alexey Lyulin, Sergey Lyulin, Andrey A. Gurtovenko
Summary: This study explores the potential of chemically modified asphaltene molecules as thermal conductivity enhancers for liquid paraffin, showing promising results for improving the thermal energy storage systems based on paraffin.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Biochemistry & Molecular Biology
Victor M. Nazarychev, Artyom D. Glova, Sergey V. Larin, Alexey V. Lyulin, Sergey V. Lyulin, Andrey A. Gurtovenko
Summary: An insight into the impact of cooling rate on phase transformations in molecular systems was gained through computational simulations on organic phase-change materials. It was found that a certain threshold in cooling rates exists, below which the simulations qualitatively reproduced experimental observations, and beyond which the simulations started to deviate considerably from experimental data.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Chemistry, Multidisciplinary
Kiumars Aryana, Hyun Jung Kim, Cosmin-Constantin Popescu, Steven Vitale, Hyung Bin Bae, Taewoo Lee, Tian Gu, Juejun Hu
Summary: Reconfigurable or programmable photonic devices have become integral in optical systems and play a crucial role in applications ranging from data communication to space exploration. Chalcogenide-based phase-change materials have shown promise in reconfigurable photonics due to their large optical contrast. This paper highlights three important aspects that impact the thermal and phase transition behavior of these devices: enthalpy of fusion, heat capacity change upon glass transition, and thermal conductivity of liquid-phase PCMs. The findings offer insights for accurate modeling and development of more efficient reconfigurable optics.
Article
Thermodynamics
L. Klochko, J. Noel, N. R. Sgreva, S. Leclerc, C. Metivier, D. Lacroix, M. Isaiev
Summary: Investigating the properties of phase change materials (PCMs) is crucial for improving heat storage systems and thermal regulation devices. This research combines molecular simulations and experimental measurements to gain a better understanding of the thermophysical and rheological characteristics of PCMs, with a focus on n-hexadecane. The results are compared to experimental data to validate the simulations.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Farideh Zeighampour, Akbar Khoddami, Hassan Hadadzadeh, Mohammad Ghane
Summary: In this study, thermophysical analysis of various nanocomposites was conducted using Molecular Dynamics simulations. The results showed that introducing graphite with nanostructure and low oxygen-containing functional groups can improve thermal conductivity. This finding is significant for the future development of high thermal conductivity phase change materials.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Energy & Fuels
D. Jamshideasli, H. Babaei, P. Keblinski, J. M. Khodadadi
Summary: Mixtures of paraffin and carbon nanofillers show potential for thermal storage, but thermal conductivity needs improvement. Molecular dynamics simulations were used to study the thermal conductance between graphene sheets and octadecane matrix, revealing that systems with thin graphene layers exhibit higher thermal conductance.
JOURNAL OF ENERGY STORAGE
(2021)
Article
Thermodynamics
Yuanying Zhang, Daili Feng, Xinxin Zhang, Yanhui Feng
Summary: Studied the methods to increase the thermal conductivity of organic phase change materials (PCM) and found that one-dimensional materials as additives have excellent thermal properties. Molecular dynamics simulations showed that nanoparticles have an impact on the thermal conductivity of pure PCM. Investigated the thermal conductivity changes of composite PCM using paraffin wax (PW) and carbon nanotube (CNT) as an example.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Energy & Fuels
Binit Kumar, Abhishek Awasthi, C. Suresh, Yongseok Jeon
Summary: This study presents a new numerical model for effective thermal conductivity that overcomes the limitations of previous models. The model can be applied to various shapes and phase change materials, using the same constants. By incorporating the natural convection effect, the model accurately calculates the thermal conductivity. The results of the study demonstrate the effectiveness of the model for different shapes and a wide range of alkanes.
JOURNAL OF ENERGY STORAGE
(2024)
Article
Thermodynamics
Myeongjin Kim, Joo Hyun Moon
Summary: This study investigates the heat transfer characteristics of a two-phase thermosyphon under different conditions using computational fluid dynamics, and reveals that thermal resistance decreases with increasing water amount, heat pipe diameter, and heater power.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Engineering, Manufacturing
Shaohua Chen, David Seveno, Larissa Gorbatikh
Summary: The study established a multiscale model to calculate the effective thermal conductivity of graphene and polyamide-6 composite, finding that randomly entangled graphene networks exhibit better thermal conductivity than composites with specific graphene alignment. The results suggest that maximizing composite thermal conductivity can be achieved by producing the optimal orientation distribution for graphene flakes without increasing graphene loading.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2021)
Article
Physics, Multidisciplinary
M. J. Leng, B. H. Wu, A. J. Lu, L. C. Wu, C. R. Wang, Z. T. Song
Summary: The study investigated the off-stoichiometric effect on the thermal and structural properties of Ge1-delta Te using molecular dynamics, showing that Ge1-delta Te still retains its ability of rapid phase transition with slightly reduced thermal conductivity as delta increases. These results are helpful for reliable device design and modeling.
Article
Energy & Fuels
Reji R. Kumar, M. Samykano, A. K. Pandey, K. Kadirgama, V. V. Tyagi
Summary: Thermal energy storage systems are crucial for modern energy production, and nano-enhanced phase change materials (NePCM) can improve the thermophysical properties of base PCM. However, the poor thermal conductivity and light transmission capability of the dispersed nanoparticles are major challenges. This research focuses on addressing those challenges by dispersing pristine and functionalized multi-walled carbon nanotubes (MWCNT and FMWCNT) in salt hydrate PCM, leading to improved thermal conductivity, latent heat, and solar spectrum absorption.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Thermodynamics
D. Bayer-Buhr, M. Vimal, A. Prakash, U. Gross, T. Fieback
Summary: The thermal accommodation coefficient alpha is assumed to be near unity for most gases, but this study shows its contribution to the effective thermal conductivity of highly porous insulation materials. The study investigates the influence of parameters like temperature, roughness, and contamination on alpha for Ar, N-2, He, and validates the assumptions used for calculations. The results also show the effects of physical adsorption and provide insights into the equivalence of alpha for SiO2 and CaSiO3.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Chemistry, Physical
Liqiu Yang, Subodh C. Tiwari, Shogo Fukushima, Fuyuki Shimojo, Rajiv K. Kalia, Aiichiro Nakano, Priya Vashishta, Paulo S. Branicio
Summary: Nonadiabatic quantum molecular dynamics is used to investigate the evolution of photoexcited states in GeTe. Results reveal a nonthermal path for the loss of long-range order induced by photoexcitation, which triggers local disorder and promotes the formation of wrong bonds. These findings provide an electronic-structure basis for understanding the ultrafast changes in the structure and properties of GeTe and other phase-change materials induced by photoexcitation.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Shabas Ahammed Abdul Jaleel, Taehun Kim, Seunghyun Baik
Summary: This study reports on leakage-free healable PCM TIMs with extraordinarily high thermal conductivity and low total thermal resistance. A matrix material called OP was synthesized by functionalizing octadecanol PCM with a polymer through a nucleophilic epoxy ring opening reaction. The introduction of thermally conductive fillers, silver flakes and multiwalled carbon nanotubes decorated with silver nanoparticles, further enhanced the thermal properties of the PCM TIMs. The OP-Ag-nAgMWNT material showed excellent heat dissipation and recycling abilities, making it a promising future TIM for thermal management.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Artyom D. Glova, Victor M. Nazarychev, Sergey Larin, Alexey Lyulin, Sergey Lyulin, Andrey A. Gurtovenko
Summary: This study explores the potential of chemically modified asphaltene molecules as thermal conductivity enhancers for liquid paraffin, showing promising results for improving the thermal energy storage systems based on paraffin.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Biophysics
Matthew Davies, A. D. Reyes-Figueroa, Andrey A. Gurtovenko, Daniel Frankel, Mikko Karttunen
Summary: A new method combining mixed radial-angular, three-particle correlation function and unsupervised machine learning was used to investigate the emergence of the ripple phase in DPPC lipid bilayers. Data from atomistic molecular dynamics simulations of varying system sizes were analyzed, revealing four distinct conformational populations of lipids. The presence of ordered, disordered, and splayed tail lipids was observed, with spatial clustering of disordered lipids in the groove side of the ripple phase. Principal component analysis confirmed the existence of the four lipid groups.
BIOPHYSICAL JOURNAL
(2023)
Article
Polymer Science
Sofia D. Melnikova, Sergey V. Larin
Summary: The effect of layer thickness and polymers compatibility on the structure and properties of coextruded multilayer polymer films was studied using molecular dynamics simulations. The results show that films with incompatible polymers have stable structures and low interfacial diffusion depth, even at nanoscale layer thickness. These films also exhibit anisotropic polymer atom mobility and two glass transition temperatures. In contrast, films with compatible polymers have a single glass transition point and gradually increasing interfacial diffusion depth. The findings suggest the importance of understanding the relationship between layer thickness and polymers compatibility in designing multilayer polymer films.
JOURNAL OF POLYMER SCIENCE
(2023)
Article
Chemistry, Physical
Andrey A. A. Gurtovenko, Victor M. M. Nazarychev, Artem D. D. Glova, Sergey V. V. Larin, Sergey V. V. Lyulin
Summary: In this study, a coarse-grained Martini model was developed to simulate the aggregation behavior of asphaltenes. It was found that native asphaltenes form small clusters that are uniformly distributed in the system, while modified asphaltenes form larger aggregates. Additionally, the mobility of native asphaltenes is slower and the size of aggregates increases with system size.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Polymer Science
A. A. Askadskii, A. V. Matseevich, I. V. Volgin, S. V. Lyulin
Summary: The approach to predict the permeability of polymer membranes based on polyimides and polyamidoimides towards helium is described. The activation energy of helium penetration is represented by a relationship involving the van der Waals volume of the repeat unit and a set of atomic parameters characterizing the contribution of each atom and intermolecular interaction types. Factors such as the imide cycles, connection type, and polar groups have been taken into account. The obtained parameters show a strong correlation coefficient of 0.965 with the experimental data, demonstrating the possibility to search for polyimide and polyamidoimide structures with the desired permeability without the need for laborious and expensive experiments.
POLYMER SCIENCE SERIES A
(2023)
Article
Polymer Science
Maarten Boomstra, Bernard Geurts, Alexey Lyulin
Summary: In this study, molecular dynamics simulations were used to investigate the segregation of molecular weight in paraffin wax near graphene flakes. The results showed that in a liquid bidisperse paraffin composed of decane and triacontane, the paraffin molecules mainly accumulated next to the graphene, forming aligned layers. However, this segregation effect was less pronounced in polydisperse wax. Measurements of crystallinity showed that the layers of wax were highly aligned parallel to the graphene, leading to an increase in thermal conductivity.
Article
Polymer Science
Nikolaos I. Sigalas, Stan A. T. Van Kraaij, Alexey V. Lyulin
Summary: This study employs molecular-dynamics simulations to investigate the flow-induced crystallization (FIC) of isotactic polypropylene at different temperatures. The findings reveal that FIC shows the highest rate within the temperature range of T-max = 330-360 K. The pre-nucleation, nucleation, and growth stages are successfully identified by using the mean first passage time method. Notable phenomena include unexpected strain hardening near T-max and the formation of high ordering areas acting as nuclei precursors. The study also detects non-uniformly slowed segmental relaxation and independent size of critical clusters at the nucleation point.
Article
Polymer Science
Victor M. Nazarychev, Sergey V. Lyulin
Summary: In recent decades, there has been a growing interest in improving the thermal conductivity of polymers for the development of new thermal interface materials (TIM) for electronic and electrical devices. In this study, the effects of uniaxial deformation on the thermal conductivity of thermoplastic polyimides were examined using atomistic computer simulations. The results showed that the thermal conductivity coefficient is anisotropic in different directions and significantly increases in the direction parallel to the deformation.
Article
Chemistry, Physical
Artem D. Glova, Victor M. Nazarychev, Sergey V. Larin, Andrey A. Gurtovenko, Sergey V. Lyulin
Summary: Atomistic computer simulations suggest that asphaltenes with enlarged aromatic cores can improve the performance of heat storage devices based on organic phase change materials. Increasing the size of the asphaltene cores promotes the formation of extended structures in paraffin and enhances the thermal conductivity of liquid paraffin.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Thermodynamics
Mahsa Taghavi, Swapnil Sharma, Vemuri Balakotaiah
Summary: This study investigates the natural convection effects in the insulation layers of spherical storage tanks and their impact on the tanks' performance. The permeability and Rayleigh number of the insulation material are considered as key factors. The results show that as the Rayleigh number increases, new convective cells emerge and cause the cold boundary to approach the external hot boundary. In the case of large temperature differences, multiple solutions may coexist.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyang Xu, Fangjun Hong, Chaoyang Zhang
Summary: This study introduces a self-induced jet impingement device for enhancing pool boiling performance in high power electronic cooling. Through visualization and parametric investigations, the effects of this device on pool boiling performance are studied, revealing the promotion of additional liquid supply and vapor exhausting. The flow rate of the liquid jet is found to positively impact boiling performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Wenchao Ke, Yuan Liu, Fissha Biruke Teshome, Zhi Zeng
Summary: Underwater wet laser welding (UWLW) is a promising and labor-saving repair technique. A thermal multi-phase flow model was developed to study the heat transfer, fluid dynamics, and phase transitions during UWLW. The results show that UWLW creates a water keyhole, making the welding environment similar to in air laser welding.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Xingrong Lian, Lin Tian, Zengyao Li, Xinpeng Zhao
Summary: This study investigates the heat transfer mechanisms in natural fiber-derived porous structures and finds that thermal radiation has a significant impact on the thermal conductivity in low-density regions, while natural convection rarely occurs. Insulation materials derived from micron-sized natural fibers can achieve minimum thermal conductivity at specific densities. Strategies to lower the thermal conductivity include increasing porosity and incorporating nanoscale pores using nanosize fibers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Yasir A. Malik, Kilian Koebschall, Stephan Bansmer, Cameron Tropea, Jeanette Hussong, Philippe Villedieu
Summary: Ice crystal icing is a significant hazard in aviation, and accurate modeling of sticking efficiency is essential. In this study, icing wind tunnel experiments were conducted to quantify the volumetric liquid water fraction, sticking efficiency, and maximum thickness of ice layers. Two measurement techniques, calorimetry and capacitive measurements, were used to measure the liquid water content and distribution in the ice layers. The experiments showed that increasing wet bulb temperatures and substrate heat flux significantly increased sticking efficiency and maximum ice layer thickness.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinqi Hu, Tongtong Geng, Kun Wang, Yuanhong Fan, Chunhua Min, Hsien Chin Su
Summary: This study experimentally examined the heat dissipation of vibrating fans and demonstrated its inherent mechanism through numerical simulation. The results showed that the flow fields induced by the vibrating blades exhibited pulsating features and formed large-scale and small-scale vortical structures, significantly improving heat dissipation. The study also identified the impacts of different blade structures and developed a trapezoidal-folding blade, which effectively reduced the maximum temperature of the heat source and alleviated high-temperature failure crisis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Dan-Dan Su, Xiao-Bin Li, Hong-Na Zhang, Feng-Chen Li
Summary: The boiling heat transfer of low-boiling-point working fluid is a common heat dissipation technology in electronic equipment cooling. This study analyzed the interfacial boiling behavior of R134a under different conditions and found that factors such as the initial thickness of the liquid film, solid-liquid interaction force, and initial temperature significantly affect the boiling mode and thermal resistance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyi Wu, Dongke Sun, Wei Chen, Zhenhua Chai
Summary: A unified lattice Boltzmann-phase field scheme is proposed to simulate dendrite growth of binary alloys in the presence of melt convection. The effects of various factors on the growth are investigated numerically, and the model is validated through comparisons and examinations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shaokun Ge, Ya Ni, Fubao Zhou, Wangzhaonan Shen, Jia Li, Fengqi Guo, Bobo Shi
Summary: This study investigated the temperature distribution of main cables in a suspension bridge during fire scenarios and proposed a prediction model for the maximum temperature of cables in different lane fires. The results showed that vehicle fires in the emergency lane posed a greater thermal threat to the cables.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shuang-Ying Wu, Shi-Yao Zhou, Lan Xiao, Jia Luo
Summary: This paper investigates the two-phase flow and heat transfer characteristics of low-velocity jet impacting on a cylindrical surface. The study reveals that the heat transfer regimes are non-phase transition and nucleate boiling with the increase of heat transfer rate. The effects of jet impact height and outlet velocity on local surface temperatures are pronounced at the non-phase transition stage. The growth rates of heat transfer rate and liquid loss rate increase significantly from the non-phase transition to nucleate boiling stage.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Emad Hasani Malekshah, Wlodzimierz Wlodzimierz, Miros law Majkut
Summary: Cavitation has significant practical importance and can be controlled by air injection. This study investigates the natural to ventilated cavitation process around a hydrofoil through numerical and experimental methods. The results show that the location and rate of air injection have a meaningful impact on the characteristics of cavitation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Feriel Yahiat, Pascale Bouvier, Antoine Beauvillier, Serge Russeil, Christophe Andre, Daniel Bougeard
Summary: This study explores the enhancement of mixing performance in laminar flow equipment by investigating the generation of chaotic advection using wall deformations in annular geometries. The findings demonstrate that the combined geometry can achieve perfect mixing at various Reynolds numbers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Hui He, Ning Lyu, Caihua Liang, Feng Wang, Xiaosong Zhang
Summary: This study investigates the condensation, frosting, and defrosting processes on superhydrophobic surfaces with millimeter-scale structures. The results reveal that the structures can influence the growth and removal of frost crystals, with the bottom grooves creating a frost-free zone and conical edges promoting higher frost crystal heights. Two effective methods for defrosting are observed: hand-lifting the groove and airfoil retraction contraction on protruding structures. This research provides valuable insights into frost formation and defrosting on millimeter-structured superhydrophobic surfaces, with potential applications in anti-frost engineering.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Thiwanka Arepolage, Christophe Verdy, Thibaut Sylvestre, Aymeric Leray, Sebastien Euphrasie
Summary: This study developed two thermal concentrators, one with a 2D design of uniform thickness and another with a 3D design, using the coordinate transformation technique and metamaterials. By structuring the thermal conductor, the desired local density-heat capacity product and anisotropic thermal conductivities were achieved. The homogenized thermal conductivities were obtained from finite element simulations and cylindrical symmetry consideration. A 3D concentrator was fabricated using 3D metal printing and characterized using a thermal camera. Compared to devices that solely consider anisotropic conductivities, the time evolution characteristics of the metadevice designed with coordinate transformation were closer to those of an ideal concentrator.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Liangyuan Cheng, Qingyang Wang, Jinliang Xu
Summary: In this study, we investigated the supercritical heat transfer of CO2 in a horizontal tube with a diameter of 10.0 mm, covering a wide range of pressures, mass fluxes, and heat fluxes. The study revealed a non-monotonic increase in wall temperatures along the flow direction and observed both positive and negative wall temperature differences between the bottom and top tube. The findings were explained by the thermal conduction in the solid wall interacting with the stratified-wavy flow in the tube.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)