Journal of Non-Equilibrium Thermodynamics最新文献_第10页

Thermal Shear Waves Induced in Mesoscopic Liquids at Low Frequency Mechanical Deformation 介观液体低频机械变形诱导的热剪切波

IF 6.6 3区工程技术

Journal of Non-Equilibrium Thermodynamics Pub Date : 2022-03-14 DOI: 10.1515/jnet-2021-0091

E. Kume, L. Noirez

{"title":"Thermal Shear Waves Induced in Mesoscopic Liquids at Low Frequency Mechanical Deformation","authors":"E. Kume, L. Noirez","doi":"10.1515/jnet-2021-0091","DOIUrl":"https://doi.org/10.1515/jnet-2021-0091","url":null,"abstract":"Abstract We show that a confined viscous liquid emits a dynamic thermal response upon applying a low frequency (∼1 Hz) shear excitation. Hot and cold thermal waves are observed in situ at atmospheric pressure and room temperature, in a viscous liquid (polypropylene glycol) at various thicknesses ranging from 100 µm up to 340 µm, upon applying a mechanical oscillatory shear strain. The observed thermal effects, synchronous with the mechanical excitation, are inconsistent with a viscous behaviour. It indicates that mesoscopic liquids are able to (partly) convert mechanical shear energy in non-equilibrium thermodynamic states. This effect called thermo-elasticity is well known in solid materials. The observation of a thermal coupling to the mechanical shear deformation reinforces the assumption of elastically correlated liquid molecules. The amplitude of the thermo-elastic waves increases linearly by increasing the shear strain amplitude up to a transition to a non-linear thermal behavior, similar to a transition from an elastic to plastic regime. The thermo-elastic effects do not give rise to any change in stress measurements and thus the dynamic thermal analysis provides unique information about dynamic liquid properties.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2022-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42055871","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}

引用次数: 3

Shock Wave in van der Waals Gas 范德华气体中的冲击波

IF 6.6 3区工程技术

Journal of Non-Equilibrium Thermodynamics Pub Date : 2022-02-15 DOI: 10.1515/jnet-2021-0099

A. Avramenko, I. V. Shevchuk, N. Dmitrenko

引用次数: 4

Variational Approach to Fluid-Structure Interaction via GENERIC 流固耦合的泛型变分方法

IF 6.6 3区工程技术

Journal of Non-Equilibrium Thermodynamics Pub Date : 2022-02-11 DOI: 10.1515/jnet-2021-0081

D. Peschka, Andrea Zafferi, L. Heltai, Marita Thomas

引用次数: 3

Effect of Cross-Sectional Geometry on Hydrothermal Behavior of Microchannel Heat Sink 截面几何形状对微通道散热器水热行为的影响

IF 6.6 3区工程技术

Journal of Non-Equilibrium Thermodynamics Pub Date : 2022-02-09 DOI: 10.1515/jnet-2021-0067

Faraz Ahmad, F. Ahmed, H. Ali, Zabdur Rehman, Muhammad Suleman, Izaz Raouf

{"title":"Effect of Cross-Sectional Geometry on Hydrothermal Behavior of Microchannel Heat Sink","authors":"Faraz Ahmad, F. Ahmed, H. Ali, Zabdur Rehman, Muhammad Suleman, Izaz Raouf","doi":"10.1515/jnet-2021-0067","DOIUrl":"https://doi.org/10.1515/jnet-2021-0067","url":null,"abstract":"Abstract The aim of this paper is to numerically analyze the hydrothermal behavior of different cross-sectional geometries of microchannel heat sinks (MCHSs) and conduct a comparative analysis of traditional and non-traditional designs using ANSYS Fluent. It is expected that the proposed design discussed in this paper will improve the performance of MCHSs by maximizing the cooling capability and minimizing the thermal resistance and entropy generation rate, thus leading to better energy efficiency. The channel designs include a rectangular microchannel (RMC), a circular microchannel (CMC), an elliptical microchannel (EMC), a trapezoidal microchannel (TMC), a hexagonal microchannel (HMC), and a new microchannel (NMC) which has a plus-like shape. The discussed geometry of the NMC is designed in such a way that it maximizes the cross-sectional area and the wetted perimeter of the channel, keeping the hydraulic diameter constant ( D h = 412{D_{h}}=412 µm). The performance of various channels is compared on the basis of pressure drop, wall temperature, thermal enhancement factor, thermal resistance, thermal transport efficiency, and entropy generation rates. It has been observed that the NMC is capable of cooling effectively and it can achieve a minimum wall temperature of 305 K, thus offering the lowest thermal resistance ( R th {R_{mathrm{th}}}), irreversible heat loss, and entropy generation rate. Moreover, the NMC has achieved the highest value of the thermal enhancement factor, i. e., 1.13, at Re = 1 , 000mathrm{Re}=1,000. Similarly, it has the highest thermal transport efficiency of almost 97 % at Re = 1 , 000mathrm{Re}=1,000, followed by the TMC and the RMC. Overall, the NMC has achieved the best performance in all aspects, followed by the RMC and TMC. The performance of the EMC, the CMC, and the HMC was found to be the worst in this study.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2022-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42492276","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}

引用次数: 4

Sources of Finite Speed Temperature Propagation 有限速度温度传播的来源

IF 6.6 3区工程技术

Journal of Non-Equilibrium Thermodynamics Pub Date : 2022-02-09 DOI: 10.1515/jnet-2021-0078

P. M. Mariano, M. Spadini

引用次数: 4

Optimizing the Piston Paths of Stirling Cycle Cryocoolers 斯特林循环低温冷却器活塞路径的优化

IF 6.6 3区工程技术

Journal of Non-Equilibrium Thermodynamics Pub Date : 2022-02-09 DOI: 10.1515/jnet-2021-0073

R. Paul, K. Hoffmann

{"title":"Optimizing the Piston Paths of Stirling Cycle Cryocoolers","authors":"R. Paul, K. Hoffmann","doi":"10.1515/jnet-2021-0073","DOIUrl":"https://doi.org/10.1515/jnet-2021-0073","url":null,"abstract":"Abstract The ideal Stirling cycle provides a clear control strategy for the piston paths of ideal representations of Stirling cycle machines. For non-equilibrium Stirling cycle machines however, piston paths aiming to emulate the ideal cycle’s four strokes will not necessarily yield best performance. In this contribution, we ask the question: What are the COP-optimal piston paths for specific non-equilibrium Stirling cryocoolers? To this end, we consider a low-effort Stirling cryocooler model that consists of a set of coupled ordinary differential equations and takes several loss phenomena into account. For this model and an exemplary parameter set, piston path optimizations are done with an indirect iterative gradient method based on optimal control theory. The optimizations are repeated for two different kinds of volume constraints for the working spaces: one representing an alpha-Stirling configuration, the other a beta-Stirling configuration. Compared to harmonic piston paths, the optimal piston paths lead to significant improvements in COP of ca. 88 % for the alpha-Stirling and ca. 117 % for the beta-Stirling at the maximum-COP operational frequency. Additionally—and even though the optimizations were performed for maximum COP—cooling power was increased with even lager ratios.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2022-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45511667","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}

引用次数: 35

Non-Linear Stability and Non-Equilibrium Thermodynamics—There and Back Again 非线性稳定性和非平衡热力学——来去匆匆

IF 6.6 3区工程技术

Journal of Non-Equilibrium Thermodynamics Pub Date : 2022-02-08 DOI: 10.1515/jnet-2021-0076

M. Dostalík, V. Průša

引用次数: 1

A Robust Physics-Based Calculation of Evolving Gas–Liquid Interfaces 基于物理的演化气液界面的稳健计算

IF 6.6 3区工程技术

Journal of Non-Equilibrium Thermodynamics Pub Date : 2022-02-04 DOI: 10.1515/jnet-2021-0080

Lukáš Šatura, Mária Minichová, M. Pavelka, J. Košek, A. Zubov

引用次数: 1

Non-Linear Heat Transport Effects in Systems with Defects 含缺陷系统中的非线性热传递效应

IF 6.6 3区工程技术

Journal of Non-Equilibrium Thermodynamics Pub Date : 2022-02-03 DOI: 10.1515/jnet-2021-0072

D. Jou, L. Restuccia

引用次数: 3

Pattern Formation in Thermal Convective Systems: Spatio-Temporal Thermal Statistics, Emergent Flux, and Local Equilibrium 热对流系统的模式形成：时空热统计、紧急通量和局部平衡

IF 6.6 3区工程技术

Journal of Non-Equilibrium Thermodynamics Pub Date : 2022-01-24 DOI: 10.1515/jnet-2021-0079

Atanu Chatterjee, T. Ban, Atsushi Onizuka, G. Iannacchione

{"title":"Pattern Formation in Thermal Convective Systems: Spatio-Temporal Thermal Statistics, Emergent Flux, and Local Equilibrium","authors":"Atanu Chatterjee, T. Ban, Atsushi Onizuka, G. Iannacchione","doi":"10.1515/jnet-2021-0079","DOIUrl":"https://doi.org/10.1515/jnet-2021-0079","url":null,"abstract":"Abstract We discuss spatio-temporal pattern formation in two separate thermal convective systems. In the first system, hydrothermal waves (HTW) are modeled numerically in an annular channel. A temperature difference is imposed across the channel, which induces a surface tension gradient on the free surface of the fluid, leading to a surface flow towards the cold side. The flow pattern is axially symmetric along the temperature gradient with an internal circulation for a small temperature difference. This axially symmetric flow (ASF) becomes unstable beyond a given temperature difference threshold, and subsequently, symmetry-breaking flow, i. e., rotational oscillating waves or HTW appear. For the second system, Rayleigh–Bénard convection (RBC) is experimentally studied in the non-turbulent regime. When a thin film of liquid is heated, the competing forces of viscosity and buoyancy give rise to convective instabilities. This convective instability creates a spatio-temporal non-uniform temperature distribution on the surface of the fluid film. The surface temperature statistics are studied in both these systems as “order” and “disorder” phase separates. Although the mechanisms that give rise to convective instabilities are different in both cases, we find an agreement on the macroscopic nature of the thermal distributions in these emergent structures.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42389623","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}

引用次数: 2