Archives of Thermodynamics最新文献

Unsteady flow of a couple stress fluid due to sudden withdrawal of pressure gradient in a parallel plate channel 平行板通道中因压力梯度突然消失而产生的耦合应力流体的非稳态流动

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Archives of Thermodynamics Pub Date : 2024-07-12 DOI: 10.24425/ather.2024.151220

Donga Anjali, Naresh Reddimalla, J. V. Ramana Murthy

{"title":"Unsteady flow of a couple stress fluid due to sudden withdrawal of pressure gradient in a parallel plate channel","authors":"Donga Anjali, Naresh Reddimalla, J. V. Ramana Murthy","doi":"10.24425/ather.2024.151220","DOIUrl":"https://doi.org/10.24425/ather.2024.151220","url":null,"abstract":"The investigation of the couple stress fluid flow behaviour between two parallel plates under sudden stoppage of the pressure gradient is considered. Initially, a flow of couple stress fluid is developed between the two parallel plates under a constant pressure gradient. Suddenly, the applied pressure gradient is stopped, and the resulting unsteady flow is studied. This type of flow is known as run-up flow in the literature. Now the flow is expected to come to rest in a long time. Usually, these types of problems are solved by using the Laplace transform technique. There are difficulties in obtaining the inverse Laplace transform; hence, many researchers adopt numerical inversions of Laplace transforms. In this paper, the problem is solved by using the separation of variables method. This method is easier than the transform method. The velocity field is analyti-cally obtained by applying the usual no-slip condition and hyper-stick conditions on the plates, and hence the volumetric flow rate is derived at subsequent times. The steady state solution before the withdrawal of the pressure gradient is matched with the initial condition on time. The rest time, i.e. the time taken by the fluid to come to rest after the pressure gradient is withdrawn is calculated. The graphs for the velocity field at different times and different couple stress parameters are drawn. In the special case when a couple stress parameter approaches infinity, couple stress fluid becomes a viscous fluid. Our results are in good agreement with this special case.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141653876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Asymmetrical melting and solidification processes of phase change material and the challenges for thermal energy storage systems 相变材料的非对称熔化和凝固过程以及热能储存系统面临的挑战

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Archives of Thermodynamics Pub Date : 2024-07-12 DOI: 10.24425/ather.2024.151224

I. Sutjahja, A. Yusuf, Y. Anggraini, S. Ulhaq, D. Kurnia, S. Wonorahardjo

{"title":"Asymmetrical melting and solidification processes of phase change material and the challenges for thermal energy storage systems","authors":"I. Sutjahja, A. Yusuf, Y. Anggraini, S. Ulhaq, D. Kurnia, S. Wonorahardjo","doi":"10.24425/ather.2024.151224","DOIUrl":"https://doi.org/10.24425/ather.2024.151224","url":null,"abstract":"The melting and solidification processes of the organic phase change material – lauric acid exposed to air were experi-mentally studied to investigate the heat exchange and its effect on the heat transfer behaviour inside a shell as well as its phase-change characteristics. Lauric acid was placed in spherical shells made of polyvinyl chloride with diameters of 44, 63, and 74 mm. This study was based on analyses of the surface temperature and vertical temperature distribution data inside the shells. We found that the phase change characteristics were strongly related to the dominant heat transfer mech-anism. In this case, melting was dominated by convection, whereas solidification was dominated by conduction. The convection intensity increased as the shell diameter increased. Further analysis revealed the melting and solidification periods. In contrast to latent heat release accompanying solidification, latent heat absorption accompanied by melting does not occur at a constant temperature, although it has a smaller temperature gradient than does sensible heat absorption. Based on the asymmetry between the melting and solidification processes, we discuss various possible strategies by which to control the charging and discharging of the phase change material by restraining the heat transfer rate to optimise its performance as a latent thermal energy storage material.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141653667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Issues on numerical modelling of transport processes in granular reactive media – an approach with thermal relaxation 颗粒反应介质迁移过程的数值建模问题--一种热松弛方法

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Archives of Thermodynamics Pub Date : 2024-07-12 DOI: 10.24425/ather.2024.150450

S. Polesek-Karczewska, D. Kardaś

{"title":"Issues on numerical modelling of transport processes in granular reactive media – an approach with thermal relaxation","authors":"S. Polesek-Karczewska, D. Kardaś","doi":"10.24425/ather.2024.150450","DOIUrl":"https://doi.org/10.24425/ather.2024.150450","url":null,"abstract":"The steadily growing interest in applying granular media in various novel and advanced technologies, particularly in the energy sector, entails the need to gain in-depth knowledge of their thermal and flow behaviour and develop simulation predictive tools for systems’ design and optimisation. The focus of the present study is on the numerical modelling of the thermal decomposition of solid fuel grains in a packed bed while considering a non-classical description of heat transfer in such a medium. The work aims to assess the influence of the relaxation time and thermo-physical properties of the medium on the nature of the solution and highlight the factors that are the source of local non-equilibrium affecting thermal wave speed propagation. The analysis of the predicted temperature distribution was carried out based on the developed transient one-dimensional thermal and flow model, taking into account the moisture evaporation and the devolatilization of fuel particles. Obtained simulation results showed a significant increase in the temperature gradients with increased relaxation times for the case of wet granular bed. They also demonstrated the variable dynamics of thermal wave propagation due to the change in the packed bed structure with the process progress. For a relaxation time of 100 s, a several-fold increase in the temperature signal propagation speed during the fuel bed thermal decomposition was predicted.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141652318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Integrating PEM fuel cell control with building heating systems: A comprehensive thermal and control model analysis 将 PEM 燃料电池控制与建筑供暖系统相结合：热能和控制模型综合分析

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Archives of Thermodynamics Pub Date : 2024-07-12 DOI: 10.24425/ather.2024.151232

R. Matysko

引用次数: 0

Research of the physical properties of bio-based building materials with phase change material 利用相变材料研究生物基建筑材料的物理性质

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Archives of Thermodynamics Pub Date : 2024-07-12 DOI: 10.24425/ather.2024.151216

Mateusz Wendołowicz, Natalia Mikos-Nuszkiewicz, Ł. Cieślikiewicz, M. Sinka, D. Bajare, P. Łapka

{"title":"Research of the physical properties of bio-based building materials with phase change material","authors":"Mateusz Wendołowicz, Natalia Mikos-Nuszkiewicz, Ł. Cieślikiewicz, M. Sinka, D. Bajare, P. Łapka","doi":"10.24425/ather.2024.151216","DOIUrl":"https://doi.org/10.24425/ather.2024.151216","url":null,"abstract":"This article presents the results of experimental measurements of the physical properties of new environmentally friendly bio-based composite building materials containing hemp shives bonded with a magnesium binder. Some of the tested materials contained an admixture of phase change material (PCM) of variable proportions in the binder to increase the heat capacity of building elements (walls), which can positively affect room temperature regulation. Densities and porosities are key parameters describing building materials, directly affecting mechanical, acoustic, and, most importantly, hygro-thermal properties, including thermal conductivity, water vapor permeability, water absorptivity, and sorption curves. The experiment was carried out for ten different samples of bio-based building composites, differing in the bulk density ob-tained during the manufacturing process and in the PCM proportion. As part of the experiment, true density tests were conducted on a helium pycnometer. Then, the geometric densities of the tested materials (which may differ from the bulk density obtained during production) were measured using the Archimedes method, making it possible to obtain the total, closed, and open porosity values. Tests were also carried out for selected traditional building materials, such as red brick and autoclaved aerated concrete, to compare the results obtained.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141655298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Influence of wall temperature on condensation rate in duct flow of humid air: a comprehensive computational study 墙壁温度对湿空气管道流中冷凝率的影响：综合计算研究

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Archives of Thermodynamics Pub Date : 2024-07-12 DOI: 10.24425/ather.2024.151229

Jakub Bobrowski, Artur Gutkowski

{"title":"Influence of wall temperature on condensation rate in duct flow of humid air: a comprehensive computational study","authors":"Jakub Bobrowski, Artur Gutkowski","doi":"10.24425/ather.2024.151229","DOIUrl":"https://doi.org/10.24425/ather.2024.151229","url":null,"abstract":"In engineering phase-change phenomena are found in a multitude of applications, ranging from refrigeration and air con-ditioning to steam turbines and petroleum refining. This study investigates the flow of moist air in a circular duct where water vapour condenses in contact with the cold wall of the duct. The investigation delves into the relationship between the condensation mass transfer rate, the heat transfer between the bulk flow and the wall, and the temperature of the wall. The volume of fluid model coupled with the Lee evaporation-condensation model was employed. Five simulations were carried out, involving different wall temperatures while maintaining the same inlet conditions. Condensation was more pronounced at lower wall temperatures, which aligns with the expectations. The heat transfer between the bulk flow and the wall decreased with the decreasing temperature difference. Interestingly, the findings revealed that the surface heat transfer coefficient increased as the wall temperature approached the temperature of the bulk flow. The success of the study suggests potential applications in optimising thermal management systems, with implications for industries where accurate predictions of moisture behaviour and heat transfer are crucial.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141654344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Mathematical model of a three-stage vacuum ejector system 三级真空喷射系统的数学模型

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Archives of Thermodynamics Pub Date : 2024-07-12 DOI: 10.24425/ather.2024.150876

R. Matysko

引用次数: 0

Exergetic performance coefficient analysis of direct methanol fuel cell 直接甲醇燃料电池的能效系数分析

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Archives of Thermodynamics Pub Date : 2024-07-12 DOI: 10.24425/ather.2024.151230

Xinjia Guo, Zhanghao Lu, Zheshu Ma, Hanlin Song, Yuting Wang

引用次数: 0

Unsteady flow of silica nanofluid over a stretching cylinder with effects of different shapes of nanoparticles and Joule heating 硅纳米流体在拉伸圆柱体上的非稳态流动，以及不同形状的纳米颗粒和焦耳加热的影响

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Archives of Thermodynamics Pub Date : 2024-07-12 DOI: 10.24425/ather.2024.151222

R. Ali, Azhar Iqbal, Tasawar Abbass, Touqeer Arshad, Azeem Shahzad

{"title":"Unsteady flow of silica nanofluid over a stretching cylinder with effects of different shapes of nanoparticles and Joule heating","authors":"R. Ali, Azhar Iqbal, Tasawar Abbass, Touqeer Arshad, Azeem Shahzad","doi":"10.24425/ather.2024.151222","DOIUrl":"https://doi.org/10.24425/ather.2024.151222","url":null,"abstract":"Indeed, nanofluids have garnered significant interest in various fields due to their numerous advantages and potential ap-plications. The appeal of SiO2 nanofluid, in particular, lies in its low preparation cost, simple production process, controlled chemistry, environmental safety and its exceptional ability to be homogeneously suspended in the base fluid, which makes it a promising candidate for a variety of applications. In this study, we investigate the flow analysis of a water based silicon dioxide nanofluid, passing over a stretched cylinder while subjected to a continuous magnetic field, including Joule heating effects. The research involves the development of a mathematical model and the formulation of governing equations rep-resented as partial differential equations. These equations are subsequently transformed into non-linear ordinary differential equations through suitable transformations. To obtain a numerical solution, the MATLAB bvp4c solver technique is em-ployed. The study investigates the implications of dimensionless parameters on velocity and thermal distributions. It is observed that the velocity distribution f'(η) exhibits a direct relationship with the volumetric fraction ϕ and an inverse relationship with the unsteadiness parameter S, the magnetic parameter M, and the temperature distribution θ(η) shows an enhancement for the increasing ϕ and M, as well as the Eckert number. However, it declines against S and the Prandtl number. The results for local Nusselt number and skin frictions are depicted in Tables.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141652983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Convection and heat transfer analysis of Cu-water rotatory flow with non-uniform heat source 具有非均匀热源的铜-水旋转流的对流和传热分析

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Archives of Thermodynamics Pub Date : 2024-07-12 DOI: 10.24425/ather.2024.151225

A. Prathiba, P. Babu, Manthri Sathyanarayana, B. Tulasi, Lakshmi Devi, Shanker Bandari

{"title":"Convection and heat transfer analysis of Cu-water rotatory flow with non-uniform heat source","authors":"A. Prathiba, P. Babu, Manthri Sathyanarayana, B. Tulasi, Lakshmi Devi, Shanker Bandari","doi":"10.24425/ather.2024.151225","DOIUrl":"https://doi.org/10.24425/ather.2024.151225","url":null,"abstract":"This article explores the phenomenon of natural convection in the rotatory flow of Cu-water nanofluid under the influence of non-uniform heat source. In order to design more effective and efficient cooling systems, this work attempts to increase our understanding of how nanofluids behave in the presence of non-uniform heat sources, convection, and rotatory force. The higher order partial differential equations governing the flow are remodelled into ordinary differential equations using similarity transformations. The remodelled equations were solved using shooting methodology and the Lobatto-III A algorithm. The impacts of various parameters such as the Richardson number (1 < Ri < 4), the Schmidt number (0.5 < Sc < 2), nanoparticle’s volume fraction (0.02 < ϕ < 0.08), etc. on velocity, concentration and temperature was ana-lysed. One of the main findings of this analysis was study of the impact of the space dependent heat source (0.2 ≤ A ≤ 1) and the temperature dependent internal heat source (0 ≤ B ≤ 0.5) on the heat regulation. Furthermore, increasing the quantity of the nano-additives and improving the fluid’s thermophysical properties intensified the acceleration of the fluid elements in the flow region. The presence of spatial and temperature-sensitive parameters facilitated quantification of the effects of a standard and variable heat source in combination of Coriolis force in the case of a Cu-water flow. The findings of the investigation will be helpful in the process of medical, architectural planning systems, oil recovery systems and so on.","PeriodicalId":45257,"journal":{"name":"Archives of Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141653433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0