Nauki Techniczne

Archives of Thermodynamics

Zawartość

Archives of Thermodynamics | 2024 | vol. 45 | No 3

Abstrakt

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.
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Autorzy i Afiliacje

Sylwia Polesek-Karczewska
1
Dariusz Kardaś
1

  1. Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, Gdańsk PL 80-231, Poland

Abstrakt

Impinging jets are one of the most effective techniques of heat transfer intensification, therefore they are continuously applied in various engineering areas. On the other hand, a numerical modelling of complex phenomena contributing to an overall heat transfer effect (and the Nusselt number value) is still not sufficient and suffers from lack of generalization. The extensive studies have been conducted to unify approach to the impinging jet modelling and construct the model (in Ansys Fluent software), which allows mirroring of the results. Presented work discusses differences in representation of impinging jet between various turbulence models based on the turbulence kinetic energy, momentum and energy budgets. It allows deep understanding of influence of geometrical and flow parameters on fluid mechanics phenomena interaction and final effect. The most significant results are connected with linking of Nusselt number distribution with analyzed budgets’ terms. Each term contributes to the distribution and cannot be omitted. Drawn conclusions explain the origin of reported in litera-ture differences and includes suggestions, how to evaluate the Nusselt number distribution results coming from various turbulence models. At this stage of research to have a complete image of relation between the particular quantities budgets and heat transfer effect it is suggested to consider also the turbulence kinetic energy dissipation budget, which will fil opened by this research gap.
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Autorzy i Afiliacje

Sebastian Gurgul
1
Elzbieta Fornalik-Wajs
1

  1. AGH University of Krakow, Al. Mickiewicza 30, Krakow 30-059, Poland

Abstrakt

This paper presents a mathematical model of a vapour vacuum system, which is a crucial component of steam power plants of critical importance for energy efficiency. This system consists of three stages, with each stage containing a steam ejector and a gas phase separator in the form of an interstage heat exchanger. The primary purpose of this system is to remove inert gases and maintain the appropriate level of vacuum in the power plant condenser. The presented mathematical model can be used to analyse the operation of the vacuum system in a steady state. Preliminary pressure calculations in various components of the vacuum system show the influence of additional measurement orifice resistance on the vacuum drop in the condenser, which can reduce the efficiency of the entire energy system. It is worth noting that the presented model can be used as a tool for analysing elements of the vacuum system in energy systems.
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Autorzy i Afiliacje

Robert Matysko
1

  1. Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, Gdańsk 80-231, Poland

Abstrakt

The article presents a comprehensive computational fluid dynamics analysis of the adsorption and desorption cycles in adsorption refrigeration systems, focusing on the impact of the adsorbent bed geometry. The entire adsorption/desorption cycle has been modeled, allowing for the observation of events during the transitional period between processes and how these influence their progression. This approach is a novelty in the field. The developed numerical model was verified against experimental data available in the literature, demonstrating excellent convergence with the experiment, with a de-viation not exceeding 2%. The study illustrates how the geometrical parameters such as height and length of the bed affect the efficiency of the adsorption and desorption processes, emphasizing the importance of bed geometry in the adsorption of heat and mass exchangers in energy and adsorbate transfer. The research findings provide valuable insights for designing more efficient cooling devices using adsorption technology, highlighting the role of bed geometry in optimizing these systems. Modeling the entire adsorption/desorption cycle is a novelty and allows for the observation of what happens during the transitional period between processes and how this influences their progression.
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Autorzy i Afiliacje

Szymon Janusz
1 2
Marcin Borcuch
2
Piotr Cyklis
1

  1. Cracow University of Technology, Jana Pawla II 37, 31-864 Kraków, Poland
  2. M.A.S. Sp z o.o., Research and Development Department, Składowa 34, 27-200 Starachowice, Poland

Abstrakt

The paper presents a modified in-house model for calculating heat transfer coefficients during flow condensation, which can be applied to a variety of working fluids, but natural refrigerants in particular, at full range thermodynamic parameters with a particular focus on increased saturation pressure. The modified model is based on a strong physical basis, namely the hypothesis of analogy between the heat transfer coefficient and pressure drop in two-phase flow. The model verification is based on a consolidated database that consists of 1286 data points for 7 natural refrigerants and covers the reduced pressure range (the ratio of critical pressure and saturation pressure) from 0.1 to 0.8 for different mass velocities and diameters. The new version of the in-house model, developed earlier by Mikielewicz, was compared with 4 other mathe-matical models widely recommended for engineering calculations and obtained the best consistency results. The value of the mean absolute percentage error was 28.13% for the modified model, the best result among the scrutinised methods.
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Autorzy i Afiliacje

Stanisław Głuch
1
Dariusz Mikielewicz
1

  1. Gdańsk University of Technology, Faculty of Mechanical Engineering and Ship Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland

Abstrakt

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.
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Autorzy i Afiliacje

Mateusz Wendołowicz
1
Natalia Mikos-Nuszkiewicz
1
Łukasz Cieślikiewicz
1
Maris Sinka
2
Diana Bajare
2
Piotr Łapka
1
ORCID: ORCID

  1. Warsaw University of Technology, Faculty of Power and Aeronautical Engineering, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw, Poland
  2. Riga Technical University, Faculty of Civil Engineering, Institute of Materials and Structures, Kalku 1, LV-1658 Riga, Latvia

Abstrakt

This study provides a simple and effective decision-making method to choose the best phase-change material for different energy storage applications. Three case studies are provided to demonstrate the proposed decision-making method. The first case study addresses the problem of best phase-change material selection for a domestic water heating latent heat storage system by considering 15 different phase-change materials and 8 selection attributes; the second case study addresses the problem of selecting the best phase-change material for a triple tube heat exchanger unit by considering 12 different phase-change materials and 5 selection attributes; the third case study addresses the problem of best phase-change material selection for latent heat thermal energy storage within the walls of Trombe to enhance performance considering 11 phase-change materials and 4 selection attributes. The results of the proposed decision-making method are compared with those of other well-known multi-attribute decision-making methods. The proposed method is shown to be simple to implement, providing a logical way for allocating weights to the selection attributes and adaptable to phase-change material selection problems in different energy storage contexts.
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Autorzy i Afiliacje

Ravipudi Venkata Rao
1

  1. Sardar Vallabhbhai National Institute of Technology, Ichchanath, Surat-395007, India

Abstrakt

This paper presents an analysis of the heat flow in a plate heat exchanger located at a building heat exchange station. The plate heat exchanger is the main source of heat for the building system based on microsubstations in the building apartments. The co-operation of the heat exchange station with the substations in the apartments is also described. Such microstations are intended for both domestic hot water preparation and apartment heating. The method of calculating the product of the heat transfer coefficient k and the heat exchange surface area A is presented. In order to verify the correctness of the measured values of the temperatures of hot and cold water at the heat exchange station inlet and outlet, they were compared to the values calculated using the -NTU method. Good agreement was found between the results of the calculations and the meas-urements. Recommendations were made for the temperature of return water to the heating station. The cost of operating the district heating network could be reduced by increasing the surface area of central heating radiators in apartments, so that the temperature of return water to the heating station could be lowered.
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Autorzy i Afiliacje

Dawid Taler
1
Tomasz Sobota
1
Jan Taler
2
Agata Kania
3
Robert Wiśniewski
3

  1. Department of Thermal Processes, Air Protection and Waste Utilization, Cracow University of Technology, ul. Warszawska 24, Cracow 31-155, Poland
  2. Department of Energy, Cracow University of Technology, al. Jana Pawla I 37, Cracow 31-864, Poland
  3. MPEC S.A. in Cracow, Al. Pokoju 81, 31-564 Cracow, Poland

Abstrakt

Graphene oxide nanoparticles with higher thermal conductivity aid in enhancing the flow and heat transport in magnetohy-drodynamic devices such as magnetohydrodynamic pumps. Modelling such devices with promising applications inherently necessitates entropy studies to ensure efficient models. This investigation theoretically studies the entropy generation in magnetohydrodynamic flow of graphene oxide in an inclined channel. Buongiorno nanofluid model is used including the impacts of nanoparticle attributes, namely thermophoretic and Brownian diffusion along with viscous dissipation effects. The spectral quasi-linearization method with Chebyshev’s polynomials is adapted to solve the differential equations under slip conditions. On studying the effects of implanted parameters, it is concluded that the conductive heat transfer enhancement by the Hartmann number is remarked. The Bejan number is found to be greater than 0.9 and hence, heat transfer primarily causes the entropy generation. A good agreement is found between the results for special cases and the results from the literature. Furthermore, investigations conclude that entropy is contributed primarily by heat transfer.
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Autorzy i Afiliacje

Jagadeeshwar Pashikanti
1
Santhosh Thota
1
Susmitha Priyadharshini
1

  1. Indian Institute of Information Technology Tiruchirappalli, Trichy - Madurai Highway, Sethurapatti, Tamil Nadu 620012, India

Abstrakt

There is no doubt that the miniaturization of various electronic devices, including processors, servers, micro-electromechan-ical system devices, etc. has resulted in increased overall performance. However, there is a major problem with thermal management in these devices, as well as in many others. One of the most promising solutions is liquid cooled microchannel heat sink. In the current work, different cases of open micro pin-fin configurations of heat sink were considered. The con-figurations considered were a uniform height micro pin-fin heat sink, three-stepped unidirectional micro pin-fin heat sink and three-stepped bi-directional micro pin-fin heat sink. These configurations were also oriented in two dissimilar fashions, i.e. inline and staggered, so the total of six heat sink configurations are compared and analysed. Using single phase water as a coolant and copper as a substrate, these configurations were simulated numerically for different Reynolds numbers (10−160) under heat flux of 500 kW/m2. It can be concluded that at low Reynolds numbers, steepness does not contribute much in both inline and staggered arrangements, while at higher Reynolds numbers, 3 stepped staggered configurations has revealed the best performance due to boosted fluid mixing and more projecting secondary flow. Furthermore, bi-direction-ality in steepness shows augmented performance only in inline arrangement.
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Autorzy i Afiliacje

Prabhakar Bhandari
1
Bhavesh Vyas
2
Diwakar Padalia
3
Lalit Ranakoti
4
Yogesh Kumar Prajapati
5
Raghubeer Singh Bangari
6

  1. Department of Mechanical Engineering, School of Engineering and Technology, K. R. Mangalam University, Gurugram-122103, Haryana, India
  2. Department of Electrical and Electronics Engineering, School of Engineering and Technology, K. R. Mangalam University, Gurugram-122103, Haryana, India
  3. Department of Physics, School of Basic and Applied Sciences, K. R. Mangalam University, Gurugram-122103, Haryana, India
  4. Department of Mechanical Engineering, Graphic Era Deemed to Be University, Dehradun-248002, Uttarakhand, India
  5. Department of Mechanical Engineering, BIT Sindri, Dhanbad-828123, Jharkhand, India
  6. Department of Mechanical Engineering, Graphic Era Hill University, Dehradun-248002, Uttarakhand, India

Abstrakt

This paper investigates entropy generation rate in a temperature-dependent variable viscosity unsteady nanofluid flow past a convectively heated impulsively moving permeable cylindrical surface. The governing equations based on the modified Stokes first problem assumption are obtained and transformed using appropriate similarity variables into nonlinear ordinary differential equations. The numerical shooting method together with the Runge-Kutta Fehlberg integration scheme are employed to effectively solve the problem. The effects of related parameters on the nanofluid velocity, temperature, skin friction, Nusselt number, entropy generation rate and Bejan number are displayed graphically and quantitatively explained. It is found that an upsurge in nanoparticles volume fraction enhances the skin friction, Nusselt number, entropy production rate and the Bejan number.
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Autorzy i Afiliacje

Itumeleng Chokoe
1
Oluwole Daniel Makinde
1
Ramotjaki Lucky Monaledi
1

  1. Stellenbosch University, Faculty of Military Science, Private Bag X2, Saldanha, 7395, South Africa

Abstrakt

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.
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Autorzy i Afiliacje

Ramzan Ali
1
Azhar Iqbal
2
Tasawar Abbass
2
Touqeer Arshad
3
Azeem Shahzad
4

  1. University of Doha for Science and Technology, College of General Education, Department of Mathematics, Doha, Qatar
  2. Department of Mathematics, University of Wah, Wah Cantt, 47040, Pakistan
  3. Department of Basic Sciences, University of Engineering and Technology, Taxila,47050, Pakistan
  4. Department of Mathematical Sciences, University of Engineering and Technology, Taxila,47050, Pakistan

Abstrakt

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.
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Autorzy i Afiliacje

Jakub Bobrowski
1
Artur Gutkowski
1

  1. Lodz University of Technology, Institute of Turbomachinery, 217/221 Wólczanska, 93-005 Łódź, Poland

Abstrakt

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.
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Autorzy i Afiliacje

Inge Magdalena Sutjahja
1
Akhmad Yusuf
1
Yunita Anggraini
1
Shofi Dhiya Ulhaq
1
Daniel Kurnia
1
Surjamanto Wonorahardjo
2

  1. Physics Department, FMIPA, Institut Teknologi Bandung, Jl. Ganesha No. 10, Bandung 40132, Indonesia
  2. Building Technology Research Group, SAPPK, Institut Teknologi Bandung, Jl. Ganesha No. 10, Bandung 40132, Indonesia

Abstrakt

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.
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Autorzy i Afiliacje

Alfunsa Prathibaa
1
P. Johnson Babub
2
Manthri Sathyanarayanac
3
B. Tulasi Lakshmi Devid
4
Shanker Bandarie
5

  1. Department of Mathematics, CVR College of Engineering, Hyderabad, India
  2. Department of Physics and Electronics, St. Joseph’s Degree & PG College, 5-9-1106 King Koti, Main Road, Hyderabad - 500029, Telangana, India
  3. Department of Mathematics & Statistics, St.Joseph's Degree & PG College, 5-9-1106 King Koti, Main Road, Hyderabad - 500029, Telangana, India
  4. Department of Mathematics, Koneru Lakshmaiah Education Foundation, Telangana, India
  5. Department of Humanities and Sciences, CVR College of Engineering, Telangana, India

Abstrakt

The aim of the present work is to discuss the effect of varying thermal conductivity in a semiconducting medium under photothermal theory. An infinite elastic half-space is overlying the infinite semiconducting medium, and a constant me-chanical force is applied along the interface. The normal mode analysis method is applied to find the analytic components of displacement, stress, carrier density and temperature distribution. It was found that all physical quantities are affected by variable thermal conductivity. The novelty of the paper lies in the fact that no such a problem of variable thermal conductivity has been discussed by any researcher so far.
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Autorzy i Afiliacje

Praveen Ailawalia
1
Priyanka
2

  1. Department of Mathematics, University Institute of Sciences, Chandigarh University, Gharuan, Mohali, Punjab, India
  2. I.G.N College, Ladwa, Haryana, India

Abstrakt

The present study explores the characteristics of reacting flow in a scramjet combustor with struts, focusing particularly on implementing different injection strategies. A three-dimensional DLR scramjet combustor is utilised to assess the impact on the system, incorporating multiple injections and varying injection angles on the triangular wedge. The analysis considers three injectors with parallel, upward and downward injections at angles of 15° and 30°. The numerical investigation is con-ducted under a constant total pressure of 7.82 bar, a temperature of 340 K, and an airspeed of Mach 2 at the inlet. The results highlight the significance of injector location and shape in promoting flame stabilization. Furthermore, injection angles play a crucial role in mitigating shockwave intensity. The numerical analysis involves a steady-state Reynolds-averaged Navier-Stokes equation with the shear stress transport k–ω turbulence model. The obtained results were analyzed by examining the critical variables such as Mach number, static pressure and combustion efficiency across the combustor. Based on the com-putational results, injecting fuel upward not only increases the overall pressure loss but also enhances the subsonic regime downstream of the strut, which leads to better mixing and combustion efficiencies. This is primarily due to shockwave generation from the edges of the strut and the interactions with the fuel stream shear layers.
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Autorzy i Afiliacje

Venkateshwaran Vanamamalai
1
Padmanathan Panneerselvam
1

  1. School of Mechanical Engineering, Vellore Institute of Technology, Vellore, Tamilnadu- 632014, India

Abstrakt

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.
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Autorzy i Afiliacje

Donga Anjali
1
Naresh Reddimalla
1
Josyula Venkata Ramana Murthy
1

  1. Department of Mathematics, National Institute of Technology Warangal, Telangana 506004, India

Abstrakt

In order to improve the output performance of direct methanol fuel cell, the finite-time thermodynamic model of direct methanol fuel cell is developed in this paper. Then, mathematical expressions for energy efficiency, power density, exergy efficiency and exergy coefficient of performance are derived. In addition, the effects of operating temperature, inlet pres-sure and membrane thickness on the performance of direct methanol fuel cells are considered. The results show that the exergetic performance coefficient not only considers the exergy loss rate to minimize the loss, but also the power density of the direct methanol fuel cell to maximize its power density and improve its efficiency. Therefore, the exergetic perfor-mance coefficient is a better performance criterion than conventional power and efficiency. In addition, increasing the inlet pressure and decreasing the membrane thickness can significantly improve the exergetic performance coefficient and en-ergy efficiency.
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Autorzy i Afiliacje

Xinjia Guo
1
Zhanghao Lu
2
Zheshu Ma
1
Hanling Song
1
Yuting Wang
1

  1. College of Automobile and Traffic Engineering, Nanjing Forestry University, Nanjing, 210037, China
  2. School of Mechanical and Automobile Engineering, Jinken College of Technology, Nanjing, 211156, China

Abstrakt

In this study, an irreversible thermodynamic model for the high temperature proton exchange membrane fuel cell taking electrochemical and heat losses into account is developed. The power density, exergy destruction index, exergy sustainability index and ecological coefficient of performance is derived. The model was validated against experimental data. The influence of parameters on the irreversible thermodynamic performance of high temperature proton exchange membrane fuel cell are considered. The multi-objective particle swarm optimization algorithm is utilized to optimize the power, ecological coeffi-cient of performance and efficiency. The population distribution of the optimization variables was analyzed using a three-dimensional Pareto frontier analysis, and results show that the maximum power density, maximum efficiency and maximum ecological coefficient of performance being 6340 W/m2, 64.5% and 1.723 respectively, which are 43.28%, 3.7% and 17.8% higher than the preoptimized high temperature proton exchange membrane fuel cell. Moreover, the nondominated sorting genetic algorithm II and simulated annealing algorithm have been chosen versus multi-objective particle swarm optimization algorithm for making the optimization comparative analysis.
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Autorzy i Afiliacje

Yuting Wang
1
Zheshu Ma
1
Yongming Gu
1
Qilin Guo
1

  1. Nanjing Forestry University, College of Automobile & Traffic Engineering, 210037, China

Abstrakt

In the paper, a model of a heated building using a PEM (proton exchange membrane) fuel cell is presented. This work introduces a novel and more comprehensive depiction of the thermal processes occurring within a fuel cell under transient conditions. The developed PEM fuel cell model was synergistically incorporated with a thermodynamic model of a build-ing. The resulting mathematical framework provides insights into the building's performance concerning fluctuating am-bient temperatures and the heating system powered by the PEM cell. The developed mathematical model delineates the interplay between the building's thermodynamics and the fuel cell in the context of the devised heating control system featuring an indirect heat distribution mechanism.
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Autorzy i Afiliacje

Robert Matysko
1

  1. Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 st., Gdańsk 80-231, Poland

Abstrakt

Most high-quality solar panel products suffer from performance degradation at an annual rate of 0.4–0.5% per year during their specified normal operational life of 25–30 years. This percentage increases in areas with hot climates and roof photovol-taic systems and varies according to the quality, guarantee and reliability of the solar panel manufacturers. The aim of this research is to assess the degradation rates of solar panels in the city of Baghdad and to determine their impact on the investment feasibility of residential systems under hot climatic conditions. In this research, an evaluation of performance of photovoltaic solar panels working in a 2 kWp system connected to the electrical grid was done under the operational climatic conditions in the evaluation area (Baghdad, Iraq). The degradation rate of all photovoltaic system modules during the operation time from 2015–2023 is equal to 4.74% (0.593% / year). For comparison, a new monocrystalline solar panel of power 185.94 Wp with an old solar panel of monocrystalline type of power 183.33 Wp (which previously was installed in 2015) were installed at the same tilt angle of 30o, and evaluated during the operation months starting in March and ending in November of the year 2023. The degradation rates per year of an aged solar panel were determined to range from 0.441% to 0.850%, with an average value of 0.788% per year. After undergoing a correction process to align the maximum power values of the old and new solar panels, the corrected degradation rates per year values ranged from 0.391% to 0.684% per year, with an average value of 0.621% per year, which closely matches the degradation rate of all photovoltaic system modules at 0.593% per year.
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Autorzy i Afiliacje

Ali Hussein Obaid
1
Emad Jaleel Mahdi
1
Isam Azeez Hassoon
1
Hussein Fawzi Hussein
2
Adil Abd Al-Sahib Jasime
1
Ammar Noori Jafarf
1
Ali Sabih Abdulghanig
1

  1. Ministry of Science and Technology, Directorate of Environment and Renewable Energy, Energy Management Center, 55509 Al-Jadriya, Iraq
  2. Ministry of Science and Technology, Directorate of Materials Researches, Advanced Materials Research Center, 55509 Al-Jadriya, Iraq

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The cover letter should explicitly state that the manuscript has not been previously published in any language anywhere and that it is not under simultaneous consideration or in press by another journal.

Manuscripts that have been previously rejected, or withdrawn after being returned for modification, may be resubmitted if the major criticisms have been addressed. The cover letter must state that the manuscript is a resubmission, and the former manuscript number should be provided.
All authors of the manuscript are responsible for its content; they must have agreed to its publication and have given the corresponding author the authority to act on their behalf. The corresponding author is responsible for informing the co-authors of the manuscript status throughout the submission, review, and production process.

From January 1, 2024, the authors are requested to submit their paper using a dedicated template provided at the AOT webpage https://www.imp.gda.pl/archives-of-thermodynamics/.


Notes for Contributors

Archives of Thermodynamics publishes original papers which have not previously appeared in other journals. The journal does not have article processing charges (APCs) nor article submission charges. The language of the papers is English. The authors are responsible to prepare papers with good English. All pages should be numbered.

Paper preparation quidelines

1. The manuscript should be written in very good English, using the two-column format provided in the template.

2. The heading should specify the title (as short as possible), author, his/her complete affiliation, town, zip code, country and e-mail. Please indicate the corresponding author. The heading should be followed by Abstract and Keywords.

3. More important symbols used in the paper should be listed in Nomenclature, placed below Abstract and arranged in a column, e.g.:
u – velocity, m/s
v – specific volume, m/kg etc.

The list should begin with Latin symbols in alphabetical order followed by Greek symbols also in alphabetical order and with a separate heading. Subscripts and superscripts should follow Greek symbols and should be identified with separate headings. Physical quantities should be expressed in SI units ( Système International d’Unités). In the template a dedicated area is created to put the nomenclature.

4. All abbreviations should be spelled out first time they are introduced in the text. Abbreviations should also be listed in the Nomenclature.

5. The equations should be each in a separate line. Standard mathematical notation should be used. All symbols used in equations must be clearly defined. The numbers of equations should run consecutively, irrespective of the division of the paper into sections. The numbers should be given in round brackets on the righthand side of the column.

6. Particular attention should be paid to the differentiation between capital and small letters. If there is a risk of confusion, the symbols should be explained (for example small c) in the margins. Indices of more than one level (such as Bfa) should be avoided wherever possible.

7. Computer-generated figures should be produced using bold lines and characters. No remarks should be written directly on the figures, except numerals or letter symbols only. Figures should be as small as possible while displaying clearly all the information requires, and with all lettering readable. The relevant explanations can be given in the caption.

8. The figures, including photographs, diagrams, etc., should be numbered with Arabic numerals in the same order in which they appear in the text. Each figure should have its own caption explaining the content without reference to the text.

9. The figures should also be submitted as separate graphic files in either vector formats (PostScript (PS), Encapsulated PostScript (EPS), preferable, CorelDraw (CDR), etc.) or bitmap formats (Tagged Image File Format (TIFF), Joint Photographic Experts Group (JPEG), etc.), with the resolution not lower than 300 dpi, preferably 600 dpi. These resolutions refer to images sized at dimensions comparable to those of figures in the print journal. Therefore, electronic figures should be sized to fit on single printed page and can have maximum 120 mm x 170 mm.

10. The references for the paper should be numbered in the order in which they are called in the text. Calling the references is by giving the appropriate numbers in square brackets. The references should be listed with the following information provided: the author’s surname and the initials of his/her names, the complete title of the work (in English translation) and, in addition:

The references should be placed after the acknowledgment section. The references citation in the manuscript body should be numbered: [1], [2], etc. Please use the following style of references in bibliography APA – 7th ed:

Journal citation (APA – 7th ed):
[1] Król, J., & Ocłoń, P. (2019). Sensitivity analysis of hybrid combined heat and power plant on fuel and CO2 emission allowances price change. Energy Conversion and Management, 196, 127–148.
doi.org/10.1016/j.enconman.2019.05.090

[2] Zhou, Y., Bi, H., & Wang, H. (2023). Influence of the primary components of the high-speed train on fire heat release rate. Archives of Thermodynamics, 44(1), 37–61.
doi.org/10.24425/ather.2023.145876

When citing scientific papers, it is needed to provide a DOI identifier if available.
Example of citation:
• Król and Ocłoń [1] studied a hybrid CHP sensitivity on fuel and CO2 emission allowances price change.
• Zhou et al. [2] studied the influence of the primary components of the high speed train on fire heat release rate.

Book citation (APA – 7th ed):
[3] Ocłoń, P. (2021). Renewable energy utilization using underground energy systems (1st ed.). Springer Nature.
Example of citation:
• Ocłoń et al. [3] presented renewable energy systems for heating cooling and electrical energy production in buildings.

Book chapter citation (APA – 7th ed):
[4] Ciałkowski, M., & Frąckowiak, A. (2014). Boundary element method in inverse heat conduction problem. In Encyclopedia of Thermal Stresses (pp. 424–433). Springer Netherlands.
Example of citation:
• Ciałkowski and Frąckowiak [4] presented a Boundary element method application for solving inverse heat conduction problems.

Conference proceedings (APA – 7th ed):
[5] Pourghasemi, B., & Fathi, N. (2023). Validation and verification analyses of turbulent forced convection of Na and NaK in miniature heat sinks. ASME 2023 Verification, Validation, and Uncertainty Quantification Symposium, 17-19 May, Baltimore, USA.
Example of citation:
• Pourghasemi and Fathi [5] validated and verified turbulent forced convection of Na and NaK in miniature heat sinks.
For works originally published in a language other than English, the language should be indicated in parentheses at the end of the reference. Authors are responsible for ensuring that the information in each reference is complete and accurate, including the DOI number.

11. As the papers are published in English, the authors who are not native speakers of English are obliged to have the paper thoroughly reviewed language-wise before submitting for publication. When the Editors or Reviewers assess that the writing English of the manuscript is poor, the authors are obliged to correct it, and provide a Certificate of English Editing as attachment in Editorial System.

Further information

All manuscripts will undergo some editorial modification. The paper proofs (as PDF file) will be sent by e-mail to the corresponding author for acceptance, and should be returned within two weeks of receipt. Within the proofs corrections of minor and typographical errors in: author names, affiliations, articles titles, abstracts and keywords, formulas, symbols, grammatical error, details in figures, etc., are only allowed, as well as necessary small additions. The changes within the text will be accepted in case of serious errors, for example with regard to scientific accuracy, or if authors reputation and that of the journal would be affected. Submitted material will not be returned to the author, unless specifically requested. A PDF file of published paper will be supplied free of charge to the Corresponding Author. Submission of the manuscript expresses at the same time the authors consent to its publishing in both printed and electronic versions.

Transfer of Copyright Agreement

All papers are published under lincense CC BY 4.0. Once a paper has been accepted for publication, as a condition of publication, the authors are asked to send a scanned copy of the signed original of the Transfer of Copyright Agreement, signed by the Corresponding Author on behalf of all authors.

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