Applied sciences

Archives of Thermodynamics

Content

Archives of Thermodynamics | 2025 | vol. 46 | No 4

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Abstract

A two-stage ejector based on a constant rate of momentum change is a geometrical arrangement of a single-stage ejector to further improve its performance, utilising water vapour as a working fluid for both primary and secondary flows. Creating an additional secondary inlet in the single-stage ejector helps to further entrain the secondary mass flow, resulting in a better entrainment ratio. The present study utilises the constant rate of momentum change, and a 1D gas dynamic approach to compute the geometrical profile and flow parameters using MATLAB. The numerical software ANSYS Fluent 18.0 is utilised to analyse the two-stage ejector geometry. The global performance ejector entrainment was computed at on and off design conditions. The results show that the two-stage ejector entrainment ratio is significantly higher than that of the previously studied single-stage ejector. The entrainment ratio of the two-stage ejector increases to reach the on-design value of operating conditions, and then starts decreasing.
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Authors and Affiliations

Arvind Kumar
1
Surendra Kumar Yadav
1
Virendra Kumar
2
ORCID: ORCID

  1. Department of Mechanical Engineering, K.R. Mangalam University, Gurugram 122001, India
  2. Department of Mechanical Engineering, Madan Mohan Malviya University, Gorakhpur 273016, India
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Abstract

The steady laminar flow past a time-dependent radially stretching sheet with Soret and Dufour effects within a hybrid nanofluid is studied. The governing equations are transformed into ordinary differential equations utilising the similarity transformations. Successive linearization is employed to linearise the nonlinear system of equations. The resultant system of equations is solved using the Chebyshev collocation method. Plots of the velocity, temperature, and concentration for chosen parameters are displayed in conjunction with the Sherwood number, Nusselt number, and coefficient of skin friction. As the volume fraction of copper (Cu) nanoparticles increases, the important values of these variables decrease, while increasing the amount of alumina (Al2O3) nanoparticles causes them to rise. The hybrid nanofluid demonstrates a faster heat transfer rate than the nanofluid on the radially stretched surface. Additionally, it has been discovered that increasing the volume fractions of copper (Cu) nanoparticles minimizes the coefficient of skin friction, the Sherwood number, and the Nusselt number for the stretching surface, while increasing the volume fractions of alumina (Al2O3) nanoparticles boosts the skin friction coefficient, the Sherwood number, and lowers the Nusselt number. Furthermore, increasing the Dufour number maintains the Sherwood number at a constant level while decreasing the Nusselt number; in contrast, enhancing the Soret number decreases the Sherwood number and increases the Nusselt number.
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Authors and Affiliations

D. Srinivasacharya
1
M. V. Sreekantha Reddy
2

  1. Department of Mathematics, National Institute of Technology, Telangana, India
  2. Gokaraju Rangaraju Institute of Engineering and Technology, Bachupally, Hyderabad, 500090, India
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Abstract

This study investigates the hydromagnetic convection of a radiating nanofluid flowing over an exponentially stretched sheet embedded in a porous medium, with emphasis on the influences of thermal radiation, magnetic fields, Joule heating, viscous dissipation, porous permeability, and nanoparticle volume fraction on flow and heat transfer behaviour. The governing momentum and energy equations are formulated using boundary layer theory and reduced to nonlinear ordinary differential equations via similarity transformations. We numerically solve these equations using the shooting method in conjunction with the Runge-Kutta-Fehlberg integration scheme. The analysis looks at how important factors like the strength of the magnetic field, thermal radiation, Prandtl number, and how easily fluid can flow through a porous material impact the system, showing how magnetic and thermal effects play a big role in how fluids move. One of the main discoveries is that stronger magnetic fields and more thermal radiation together lower the Nusselt number, highlighting the balance between heat transfer through radiation and convection, which is important in high-temperature industrial processes. The study offers important insights for optimising a range of engineering applications, including nanomaterial-based thermal coatings, energy systems, and magnetically influenced flow control that ultimately aid advancements in energy efficiency, manufacturing processes, and environmental technologies.
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Authors and Affiliations

Adetayo Samuel Eegunjobi
1
Oluwole Daniel Makinde
2

  1. Mathematics Department, Namibia University of Science and Technology, Windhoek, Namibia
  2. Faculty of Military Science, Stellenbosch University, Private Bag X2, Saldanha 7395, South Africa
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Abstract

Besides the increasing share of uncontrollable renewables in the energy mix, the consumption/production balance of the grid must be permanently assured. Additionally, the successive stopping of traditional, fossil-fuelled power plants necessitates the controllability also of nuclear power plants. The major drawback of the load-following operation of such units is the side effect of load changes. They are, namely, carried out via non-stationary transitions, during which the temperature changes result in thermal stresses. The most critical, practically unchangeable part of the plant is the reactor pressure vessel, which is a thick-walled component of complex geometry. Hence, determining the optimal curves of the unit’s available control inputs is a crucial issue. For this, several tools are needed, such as a dynamical model of the entire power unit, a dynamical description of the thermal stress in the most critical points, a practical system of criteria of the optimisation condition, and numerical method for seeking the optimal pathway. The results demonstrate that optimised actuator trajectories can reduce thermally induced stress in the nozzle corner of the reactor pressure vessel during load-following operation.
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Authors and Affiliations

Bálint Pudleiner
1
Pál Szentannai
2
Léa Désesquelles
3
Camille Matter
4
Tamás Fekete
1

  1. HUN-REN Centre for Energy Research, Konkoly-Thege 29-33, Budapest H-1121, Hungary
  2. Department of Energy Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Muegyetem 3, Budapest H-1111, Hungary
  3. Grenoble INP - Phelma, Graduate School of Engineering in Physics, Electronics, Materials Sciences, 3 Parvis Louis Néel, CS 50257, 38016 Grenoble Cedex 1, France
  4. IMT Mines Albi, Ecole Nationale Supérieure des Mines d’Albi-Carmaux, Campus Jarlard, Cedex 09, Albi F-81013, France
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Abstract

The article presents the influence of hydraulic resistance in the main pipelines of EPR (evolutionary power reactor) and AP1000 (advanced passive) pressurised water nuclear reactors secondary circuit on the electric power of these units. The change of hydraulic resistance in the passage pipelines of the high-pressure and low-pressure turbine parts and in the pipelines supplying the low-pressure and high-pressure regenerative heaters was taken into account. These two types of units were selected due to the different values of live steam parameters and different values of pressure drops in the turbine passage and regeneration system pipelines. The analysis shows that the flow resistance in the turbine passage pipelines has the greatest impact on the power and efficiency of the unit, followed by high-pressure regeneration pipelines, while low-pressure regeneration pipelines have the least impact.
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Authors and Affiliations

Rafał Marcin Laskowski
1
Adam Smyk
1
Marcin Wolowicz
1
Jacek Szymczyk
1

  1. Warsaw University of Technology, Faculty of Power and Aeronautical Engineering, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warszawa, Poland
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Abstract

Light pollution is a growing problem in developed countries. One of its categories, often associated with this concept, is night sky glow. This glow is caused by scattering light from artificial ground light sources on atmospheric particles. The paper indicates that street lighting may be the primary source of light scattered on these particles. This is caused by often outdated luminaires or their installation, which does not protect the surroundings from light pollution. The second, even more important factor increasing the brightness of the sky glow may be the reflection of incident light upwards by the street surface. Satellite images of the Earth's surface allow for determining the radiance from a given area, determined by the amount of light scattered in the atmosphere. However, the part of this light associated with street lighting is difficult to separate from the background of other artificial ground light sources. In 2020, due to the COVID-19 pandemic and reduced traffic at night, the authorities of several municipalities in the Małopolska province in Poland decided to switch off street lighting at night. This was the first time street lighting was switched off for part of the year in large areas and entire cities. Analysis of satellite data allowed us to determine that the luminance from the analysed localities decreased by almost 70% after switching off city lighting. The analysis also allowed us to estimate the energy losses of city lighting resulting from lighting fixtures that do not protect the surroundings from light pollution.
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Authors and Affiliations

Tomasz Ściężor
1
ORCID: ORCID

  1. Cracow University of Technology, Department of Water Supply, Sewerage and Environmental Monitoring, Faculty of Environmental Engineering and Energy, Warszawska 24, 31-155 Cracow, Poland
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Abstract

This study presents a comprehensive analysis of the impact of thermal retrofit, including the heat source modernisation, on the heating load of an existing single-family building located in Szczecin, Poland (Climate Zone I). The building, constructed in 2002, originally lacked thermal insulation in the walls, roof and ceiling, resulting in high operating costs and difficulties in maintaining thermal comfort. The aim of the project was to reduce heat losses, improve energy efficiency and enhance user comfort. The scope of work included thermal insulation of external walls, roof insulation, insulation of the intermediate floor slab and exterior wall section adjacent to the door opening and to the fenestration opening. The analysis conducted using the Audytor OZC 7.0 Edu Pol software showed that the total heat load of the building decreased from 25 710 W to 9476 W, representing a reduction of over 63%. Special attention was given to the analysis of thermal bridges, which are significant sources of energy loss. Using Therm 7.8.77 software, solutions were designed to reduce heat losses in critical areas. The heat transfer coefficients (U-values) for these thermal bridges were significantly reduced – by more than 50% in some cases. As part of the heat source modernisation, the solid fuel boiler and liquefied gas tank were removed and replaced with a condensing gas boiler powered by natural gas from the municipal network. To support the domestic hot water preparation system, flat-plate solar collectors were designed to work in conjunction with the existing dual-coil storage water heater.
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Authors and Affiliations

Wiktoria Bernat
1
Katarzyna Zwarycz–Makles
1

  1. Department of Heating, Ventilation and Heat Engineering, Faculty of Civil and Environmental Engineering, West Pomeranian University of Technology in Szczecin, al. Piastow 17, 70-310 Szczecin, Poland
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Abstract

This paper proposes a modification to the Verhoff-Banchero relation describing the acid dew point temperature, based on the evaluation of a generic equation that revealed two major limitations. First, the original relation’s narrow application range was identified through comparison with the H2O-H2SO4 vapour-liquid equilibrium dataset from the literature. Second, testing of the function’s limits showed that the acid dew point temperature does not approach the water dew point temperature as the sulfuric acid concentration approaches zero. To address these limitations, the Verhoff-Banchero relation is extended into a bivariate quadratic function. Regression parameters, along with their estimation errors, are derived using the aforementioned dataset and the least squares method. Statistical test (p-value < 0.01) confirmed the significance of the introduced quadratic terms. The maximum estimation error for the modified relation is found to be ±10°C across a broad application range, with water partial pressures from 1013.25 Pa to 101325 Pa and sulfuric acid liquid mass fractions ranging from 0.1 to 0.98. Additionally, two semi-empirical relations are proposed, incorporating liquid-phase composition as an independent variable. The proposed extended Verhoff-Banchero model was evaluated using an experimental dataset for exhaust gas. Data points fall within an acceptable deviation range, with exceptions from two specific datasets. One of the observed deviations is explained by the partial derivative of the acid dew point temperature with respect to sulfuric acid partial pressure. The limitations of the proposed relations are discussed. Finally, the conclusions with potential future research directions in modelling the H2O-H2SO4 system in exhaust gas are outlined.
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Authors and Affiliations

Mateusz Przybyła
1

  1. Independent researcher, Szczecin, Poland
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Abstract

This study explores the stabilising interplay of finite Larmor radius corrections and quantum pressure on the Rayleigh-Taylor instability in a non-Newtonian, magnetised fluid. The investigation is motivated by the need to understand how quantum and magnetohydrodynamic effects jointly influence instability behaviour in complex fluid systems. The governing magnetohydrodynamic equations are linearised using normal mode analysis and appropriate boundary conditions to derive a general dispersion relation for Rayleigh-Taylor instability under the Jeffrey fluid model. Numerical results show that the combined presence of finite Larmor radius corrections and quantum pressure suppresses the growth rate of Rayleigh-Taylor instability modes. In contrast, the Jeffrey parameter amplifies instability, while quantum and finite Larmor radius effects reduce both the cut-off and critical wavenumbers.
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Authors and Affiliations

Anukampa Thakur
1
Veena Sharma
1
Gian Chand Rana
2
Poonam Gautam
3

  1. Department of Mathematics and Statistics, Himachal Pradesh University, Summer Hill, Shimla 171005, India
  2. Principal, Govrenment Degree College Dhaneta, Hamirpur, Himachal Pradesh 177041, India
  3. School of Basic Sciences, Bahra University, Waknaghat, Solan, Himachal Pradesh 173234, India
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Abstract

In the present work, an automotive three cylinder compression ignition engine employed with a common rail direct injection system, fuelled with diesel was investigated to analyse its performance and emission characteristics, and also cylinder-to-cylinder variation of important parameters of combustion. Variation of cylinder pressure, peak cycle pressure, rate of maximum pressure rise, rate of maximum heat release and combustion duration between the cylinders was presented as a function of brake mean effective pressure, torque and speed of the engine. Variation of carbon monoxide, unburnt hydrocarbon, oxides of nitrogen and brake thermal efficiency for the tested engine was presented as a function of brake mean effective pressure. It can be seen that measured combustion parameters show a significant variation between the cylinders, and the variation of the magnitude of average cylinder pressure was marginal. The peak pressure and combustion duration in cylinder 2 are higher by approx. 11% and 9%, respectively, than those of the other two cylinders. At a 40 Nm torque and at the lowest operated speed, the peak pressure in cylinder 2 is higher by 10% than that of the other two cylinders. This trend was also observed at the highest operated speed, with the peak pressure higher by approx. 14%. The maximum combustion duration in cylinder 2 was observed to be 9% higher than in the other two cylinders at identical comparable brake mean effective pressure values. It can also be seen that emission parameters were varied considerably with brake mean effective pressure and a trade-off point was obtained between NOx-CO, NOx-UBHC and NOx-BTE.
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Authors and Affiliations

Saravanan Subramania
1
Paul Durai Kumar
2
Ravi Govindasamy
2
Meenakshi Sundaram Iyamperumal
3

  1. Department of Mechanical Engineering, Sri Venkateswara College of Engineering, Chennai 602117, Tamil Nadu, India
  2. Department of Automobile Engineering, Sri Venkateswara College of Engineering, Chennai 602117, Tamil Nadu, India
  3. Chief Technology Officer – M/S Amalgamations Component Division, Chennai, India
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Abstract

Machine learning, a division of artificial intelligence (AI), empowers systems to gain knowledge from information and refine their capabilities over time. It uses algorithms to identify patterns and make prophecies or decisions. Prosopis juliflora is becoming gradually notorious as an optimistic substitute in biofuel inquiry. The mixing of Prosopis juliflora with diesel for use in combustion engines has been the subject of growing study in recent years. However, limited research has explored the impact of Prosopis juliflora on the compression ignition (CI) engine exhaust employing data-driven optimisation highlighting the need for new inquiries to address this shortfall. We aim to explore the cutting-edge and proficient machine learning driven weighted superposition attraction algorithm to optimise the efficiency and exhaust of CI engines powered with Prosopis juliflora biodiesel – diesel blends. Regression modelling is employed to define the relationships between factors such as the blend percentage and brake mean effective pressure (bar), and responses like the brake thermal efficiency (%), brake specific fuel consumption (g/kWh), smoke opacity (%), NOx (g/kWh), CO (g/kWh), and HC (g/kWh). The data-driven weighted superposition attraction algorithm is subsequently employed to determine the best factor levels. Validation of the results demonstrates that the brake thermal efficiency is enhanced, while the other response variables are effectively reduced, showcasing the effectiveness of this methodology.
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Authors and Affiliations

Sethuraman Narayanan
1
Vinodraj Subramanian
1
Thamizhvel Rajkumar
1
Vaithianathan Nadarajan
1

  1. IFET College of Engineering, IFET Nagar, Gangarampalayam Post, Valavanur Villupuram 605108, Tamil Nadu, India
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Abstract

Research aimed at increasing the efficiency of heat exchangers used in car air conditioning systems may lead to modifications in the design of refrigeration systems. One such modification involves the use of smaller gas coolers, which directly reduces the overall production costs. This study presents an experimental investigation into the impact of constructional solutions on the performance of an internal heat exchanger using propylene glycol as a refrigerant. Two internal heat exchangers with different outer channel geometries were analysed. The experimental study was complemented by numerical simulations using the computational fluid dynamics method. The results showed that modifying the outer channel geometry from a parallel to a twisted configuration led to a 5.06% increase in cooling efficiency, a reduction of the outlet temperature by 2.2°C and a nearly 72 W increase in the total heat exchange rate. Numerical simulations confirmed the experimental findings, demonstrating good agreement with the measured data.
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Authors and Affiliations

Jakub Janus
1
ORCID: ORCID
Przemysław Skotniczny
1
ORCID: ORCID
Maria Richert
1
Jacek Długopolski
2
ORCID: ORCID

  1. Strata Mechanics Research Institute, Polish Academy of Sciences, Reymonta 27, 30-059 Kraków, Poland
  2. AGH University of Science and Technology, Mickiewicza 30, 30-059 Kraków, Poland
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Abstract

Numerical studies on combined free and forced convection together with radiation in a channel comprising two plates that are vertical and parallel are made. The channel here addresses two cases, viz. symmetric, and asymmetric isothermal walls. The cooling agent could be any gaseous medium that is assumed transparent to thermal radiation. The present work considers air for the job. The equations of conservation of mass, momentum and energy are solved through the finite volume method and an explicit code is prepared for this. The prime independent parameters considered are: aspect ratio, wall emissivity, Richardson number, Grashof number and Reynolds number. The effects exhibited by these parameters on the average convection Nusselt number, and the contributory roles enacted by convection and radiation in discarding the heat in the channel have been elucidated. The correlations for the mean convection Nusselt number and mean radiation Nusselt number are deduced through regression analysis using a large set of data gathered from the computer code that is prepared as part of the present work. The gross errors that occur in the cooling load calculations upon ignoring radiation in problems of this kind are clearly demonstrated.
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Authors and Affiliations

Chiyyedu Gururaja Rao
1

  1. Department of Mechanical Engineering, Vasavi College of Engineering, Hyderabad, India
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Abstract

Squeeze film lubrication involving couple stress fluids, viscosity variation and magnetohydrodynamics is critically important for high-performance applications in automotive systems, aerospace mechanisms and biomedical devices. This study aims to examine the combined influence of these effects on lubrication performance between a cylinder and a rough porous flat surface. To achieve this, we developed a generalised modified Reynolds equation by integrating Christensen’s stochastic model for surface roughness, Darcy’s law for porous media flow, and Stokes flow theory. This equation was solved with appropriate boundary conditions to derive analytical expressions for pressure, enabling the calculation of load-carrying capacity and squeeze film time for both longitudinal and transverse roughness patterns. Key findings demonstrate that couple stress, magnetohydrodynamics effects, and viscosity variation significantly enhance pressure distribution, increasing load-carrying capacity by up to 85.29% and squeeze film time by up to 85.34% under optimal conditions. Notably, longitudinal roughness pattern degrades tribological performance, whereas transverse roughness pattern enhances it. Furthermore, three-dimensional analysis demonstrates that optimal tuning of roughness and porosity parameters maximises the system performance. These findings, validated against established results like Lin et al. [31], provide valuable design guidelines for optimising tribological systems in fields requiring precise and durable lubrication, particularly in precision manufacturing and microelectromechanical systems.
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Authors and Affiliations

Suresha Ramareddy
1
Arunkumar Rudrappa
2
Bannihalli Naganagowda Hanumagowda
3
Subramanya Raghavendra
4

  1. Department of Mathematics, Jain (Deemed-to-be University), Kanakapura Taluk, Ramanagara District 562112, Karnataka, India
  2. Department of Mathematics, Sai Vidya Institute of Technology, Bangalore 560064, Karnataka, India
  3. Department of Mathematics, GM University, Davangere 577006, Karnataka, India
  4. Department of Mechanical Engineering, Sai Vidya Institute of Technology, Bangalore 560064, Karnataka, India
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Abstract

The paper presents the results of numerical simulations and optimisation of boiler heat exchanger parameters under conditions of deep cooling of combustion products. The specific features of heat and mass transfer calculations, particularly when combustion products are cooled below the dew point with water vapour condensation, are discussed. Experimental results are provided for a large-scale (1.5 m) heat pipe filled with a water/ammonia mixture. These results are utilised in mathematical modelling and optimisation of heat exchanger performance involving heat pipes. The heat transfer process is simulated in a two-stage heat exchanger, where different sections of heat pipes are filled with different working fluids depending on the temperature zones. The optimisation is performed using the minimum entropy production method. The optimal distribution of heat flux density and temperature is determined, considering both design and operational parameters. Numerical examples are provided to demonstrate the performance of the heat recovery system. The results of numerical modelling and optimisation of the design and operating parameters of a two-stage heat exchanger of heat pipes filled with various liquids are presented. The optimal parameters of the heat exchanger are determined using the criterion of minimum entropy production.
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Authors and Affiliations

Andriy Redko
1
Adam Ujma
2
Oleksandr Redko
3
Ihor Redko
4
Vadym Zadiranov
3
Vitalii Zaika
3

  1. Sumy National Agrarian University, Gerasimа Kondratieva 160, Sumy 40000 Ukraine
  2. University of Applied Sciences in Nysa, Faculty of Technical Sciences, Armii Krajowej 7, Nysa 48-300, Poland
  3. О.М. Beketov National University of Urban Economy in Kharkiv, Marshal Bazhanov 17, Kharkiv 61002, Ukraine
  4. Ukrainian State University of Railway Transport, Maidan Feuerbach 7, Kharkiv 61001, Ukraine
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Abstract

This study examines the energy dissipation mechanisms in unsteady nanofluid flow confined between two permeable walls under a generalised Couette flow configuration, with a particular emphasis on entropy generation and convective heat transfer effects. Such an analysis is of growing significance in advanced thermal management applications, including industrial cooling processes, microelectronic systems, renewable energy technologies and biomedical devices, where nanofluids are increasingly employed to enhance thermal performance. The governing partial differential equations, derived from the conservation principles of mass, momentum, and energy, are solved numerically using a semi-discretisation finite-difference approach in conjunction with a Runge-Kutta-Fehlberg integration algorithm. Comprehensive results for velocity distribution, temperature field, skin friction coefficient, Nusselt number, entropy generation rate and Bejan number are presented and discussed. The findings reveal, among other trends, that increasing injection/suction rates and the Biot number reduce the Nusselt number, entropy generation rate and Bejan number at the stationary lower wall, while simultaneously enhancing these quantities at the upper moving wall. These results highlight the dual role of boundary conditions and thermal parameters in governing irreversibility, heat transfer efficiency and overall system performance. By offering insights into the minimisation of entropy-related losses, this work contributes to the design of more energy-efficient and sustainable nanofluid-based thermal systems.
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Authors and Affiliations

Michael Hamza Mkwizu
1
Oluwole Daniel Makinde
2

  1. Sokoine University of Agriculture, Department of Mathematics and Statistics, Chuo Kikuu, P.O. Box 3000, Morogoro, Tanzania
  2. Stellenbosch University, Faculty of Military Science, Private Bag X2, Saldanha 7395, South Africa
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Abstract

A numerical investigation has been conducted on the flow of a nanofluid over an exponentially stretching surface, a configuration relevant to many industrial heat and mass transfer applications. By applying appropriate similarity transformations, the governing partial differential equations are reduced to a set of dimensionless ordinary differential equations. These nonlinear equations are solved numerically using the fourth-order Adams–Moulton method integrated with a shooting technique to ensure accuracy and stability. The validity of the computed results is established by benchmarking them against previously published findings in the literature. Key parameters influencing the flow are illustrated and discussed through graphical representations. The study's overall findings support the conclusion that increasing the Hartmann number, Schmidt number and thermal stratification parameter reduces the thermal boundary layer thickness. Moreover, enhanced solutal stratification and chemical reaction parameters are found to suppress the nanoparticle concentration. Engineering quantities like the skin friction coefficient, Nusselt number and Sherwood number are also computed and analysed, providing insights into optimising nanofluid-based thermal systems under complex boundary conditions.
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Authors and Affiliations

Batcha Srisailam
1
Pagilla Ramesh
2
Marla Umakanth
3
Kamatam Govardhan
4
Ganji Narender
5 6

  1. Department of Humanities and Science (Mathematics), Government Polytechnic for Women (M), Badangpet, Balapur (M), Rangareddy 500058, Telangana, India
  2. Department of Statistics and Mathematics, College of Agriculture, Professor Jayashankar Telangana Agricultural University, Hyderabad 500030, Telangana, India
  3. Department of Mathematics, CMR Engineering College, Hyderabad 501401, Telangana, India
  4. Department of Mathematics, GITAM University, Hyderabad Campus, Hyderabad 502329, Telangana, India
  5. Department of Humanities and Sciences (Mathematics), CVR College of Engineering, Hyderabad 501510, Telangana, India
  6. Department of Mathematics, St. Ann’s College for Women, Hyderabad, Telangana, India
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Abstract

In this analysis, thermal performance of building roof elements subjected to periodic changes in temperature at a roof top was examined with and without insulating materials. The objective of this analysis is to reduce energy consumption and prevent heat flow through roofs by using various insulating materials on the roof slab. It aims to compare the thermal performance of roof slabs with and without insulation under different atmospheric temperature conditions. Further, the study seeks to accurately predict the roof bottom temperature using optimisation techniques in order to minimise experimental cost and time. Nine identical rooms were constructed and eight roofs were retrofitted with different insulating materials such as coconut shell, fly ash, Jhama brick bats, rice husks, glass fibre, rubber sheet, earthen pots and asbestos sheets. The roof of one room was kept untreated and was considered as a reference. The thermal behaviour of every innovative roof slab was analysed. Among the eight insulating materials considered in this study, the performance of the roof slab with fiberglass was found to be the best. Roof slab with fiberglass could provide temperature reduction in the room of about 6.17°C, whereas roof slab with earthen pot could provide temperature reduction in the room of 2.27°C. The time lag between the maximum roof top temperature and maximum room temperature was found to be maximum in the case of roof slab with fiberglass and minimum in the case of roof slab with earthen pot. The time lag between the maximum roof top temperature and maximum room temperature is 4 hours for roof slab with fiberglass. The variation of roof bottom temperature was predicted by five optimisation techniques such as cuckoo search, bacterial colony optimisation, group search optimisation, social spider optimisation and genetic algorithm. It was observed that the social spider optimisation technique predicted the temperature accurately and the error between the measured and predicted temperature values was minimum compared to the other optimisation techniques.
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Authors and Affiliations

Anil Kumar Dixit
1
Manmatha Kumar Roul
2
Bikasha Chandra Panda
3
Prajna Priyadarsini Roul
2
Sibakanta Sahu
2
Prateek Debadarsi Roul
3
Saipada B.B.P.J. Sahu
4

  1. Bhadrak Institute of Engineering & Technology, Bhadrak-756113, Odisha, India
  2. GITA Autonomous College, Bhubaneswar-752054, Odisha, India
  3. Indira Gandhi Institute of Technology, Sarang-759146, Odisha, India
  4. National Institute of Technology, Rourkela-769008, Odisha, India
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Abstract

Providing energy to troops requires maintaining optimal fuel levels across all management stages, especially within Garrison Support Units and Regional Logistic Bases. The article examines the fuel distribution system supported by a program that predicts commanders’ actions using input data from subordinate units. To aid decision-making, Garrison Support Units implemented neural network variants to model logistical activities, training, peacetime operations, or combat, and segment fuel supply accordingly. The Neural Network Toolbox from MATLAB (MathWorks) was used for computations. The study presents the Garrison Support Units operational assumptions, the role of commanders as agents, and factors affecting fuel distribution. It also outlines the development of the Logistic Decision Support System dashboard, which enables entering decision variables, neural network coefficients, and weights to forecast fuel consumption and plan future operations based on environmental and operational data. The article includes MATLAB simulation results, analysing neural network algorithms and neuron counts per layer to determine the most effective configuration for decision-making optimisation. Results show that the Bayesian regularisation algorithm achieved the lowest mean square error across all data sets and the highest prediction accuracy measured by the root mean squared error. The regression coefficient confirmed a strong correlation between predicted and actual outcomes, demonstrating the Bayesian regularisation algorithm’s effectiveness in supporting logistical fuel management decisions.
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Authors and Affiliations

Artur Kępczyński
1

  1. General Command of the Armed Force, Polish Armed Forces
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Abstract

Providing energy to troops requires maintaining optimal fuel levels across all management stages, especially within Garrison Support Units and Regional Logistic Bases. The article examines the fuel distribution system supported by a program that predicts commanders’ actions using input data from subordinate units. To aid decision-making, Garrison Support Units implemented neural network variants to model logistical activities, training, peacetime operations, or combat, and segment fuel supply accordingly. The Neural Network Toolbox from MATLAB (MathWorks) was used for computations. The study presents the Garrison Support Units operational assumptions, the role of commanders as agents, and factors affecting fuel distribution. It also outlines the development of the Logistic Decision Support System dashboard, which enables entering decision variables, neural network coefficients, and weights to forecast fuel consumption and plan future operations based on environmental and operational data. The article includes MATLAB simulation results, analysing neural network algorithms and neuron counts per layer to determine the most effective configuration for decision-making optimisation. Results show that the Bayesian regularisation algorithm achieved the lowest mean square error across all data sets and the highest prediction accuracy measured by the root mean squared error. The regression coefficient confirmed a strong correlation between predicted and actual outcomes, demonstrating the Bayesian regularisation algorithm’s effectiveness in supporting logistical fuel management decisions.
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Authors and Affiliations

Artur Kępczyński
1

  1. General Command of the Armed Force, Polish Armed Forces

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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 in Open Access under license CC BY-NC-ND 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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