Applied sciences

Archives of Thermodynamics

Content

Archives of Thermodynamics | 2026 | vol. 47 | No 1

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Abstract

The application of machine learning techniques in the renewable energy sector has revolutionised the predictive modelling and optimisation of solar thermal systems. Solar air heaters with artificial roughness and phase change materials are widely used to enhance thermal performance, necessitating accurate thermo-hydraulic performance predictions for efficient design and opera-tion. This study employs the XG-Boost machine learning model to predict thermo-hydraulic performance values based on ex-perimental data obtained for polygonal and trapezoidal rib configurations at different relative roughness pitch ratios (p/e) and Reynolds numbers (Re = 2000 to 20000) in the absorber plate of a solar air heater. The experimental results reveal that a polyg-onal rib configuration with p/e = 7.5 exhibits the highest thermo-hydraulic performance value of 2.95 at Re = 4000, while the trapezoidal rib with p/e = 7.5 achieves a thermo-hydraulic performance of 2.93 at the same Reynolds number. The results were trained in the proposed machine learning model to validate the accuracy of predicted results. The coefficient of determination R2, mean absolute percentage error, root mean squared error and mean absolute percentage error matrix were considered for the training and testing dataset. The model effectively captures the nonlinear thermal behaviour, achieving R2 = 0.976, mean absolute error at 0.045, root mean squared error at 0.056 and mean absolute percentage error of 2.42%, demonstrating superior predictive capability. Further, this study provides the significance of plethora machine learning algorithms, data pre-processing strategies, feature selection and hybrid machine learning models for performance optimisation in solar air heaters. Additionally, few case studies highlight the practical implementation of machine learning in solar energy systems, demonstrating its potential for accu-rate prediction of thermal efficiency in real time assessment. Besides, it outlines future research directions, challenges, and emerging opportunities to advance machine learning applications in sustainable energy solutions. This „review-experimental” comparative article serves as a valuable resource for researchers and industry professionals, driving innovation in solar thermal energy systems through data-driven intelligence.
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Authors and Affiliations

Balakrishnan Varun Kumar
1
Parthasarathy Rajesh Kanna
2
Chithirai Pon Selvan
3
ORCID: ORCID
Dawid Taler
4
Tomasz Sobota
4
Jan Taler
5

  1. Thiagarajar College of Engineering, Madurai 625 015, Tamil Nadu, India
  2. CO2 Research and Green Technologies Centre, Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India
  3. School - Science and Engineering, Curtin University, Dubai, United Arab Emirates
  4. Cracow University of Technology, Faculty of Environmental Engineering and Energy, Department of Thermal Processes, Air Protection and Waste Utilization, Warszawska 24, 31-155 Cracow, Poland
  5. Cracow University of Technology, Faculty of Environmental Engineering and Energy, Department of Energy, Warszawska 24, 31-864 Cracow, Poland
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Abstract

An alternative formulation of the method of weighted residuals for Fourier's law of heat conduction is presented. In one-dimensional heat conduction, when the weighting factor equals unity and the heat-penetration-depth concept is used, the method reduces to the heat flux integral method. The paper also presents a comparison of the proposed heat flux integral method with the classic heat balance integral method developed by T.R. Goodman. In the heat balance integral method, the transient heat conduction equation is integrated with respect to the spatial coordinate, whereas in the heat flux integral method, Fourier's law is integrated over the spatial coordinate. The advantage of the heat flux integral method over the heat balance integral method is the greater accuracy, especially in bodies whose thermal conductivity depends on temperature or position. The greater accuracy of the proposed method is illustrated by the determination of the transient temperature distribution in a plate with temperature-dependent thermal conductivity. Additionally, for a straight fin with temperature-dependent thermal conductivity, the heat flux integral method provides greater accuracy in determining temperature and fin efficiency than the heat balance integral method. The temperature distribution in the plate and fin, as well as the fin efficiency, were also deter-mined using the finite volume method to assess the accuracy of the heat flux integral method and heat balance integral method.
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Authors and Affiliations

Jan Taler
2
Dawid Taler
1

  1. Cracow University of Technology, Faculty of Environmental Engineering and Energy, Department of Thermal Processes, Air Protection and Waste Utitilisation, 31-155 Cracow, Poland
  2. Cracow University of Technology, Faculty of Environmental Engineering and Energy, Department of Energy, 31-864 Cracow, Poland
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Abstract

This study proposes a new correlation to predict the effective thermal conductivity of carbon-nanotube nanofluids by account-ing for both carbon-nanotube characteristics (thermal conductivity, density, diameter and length) and base-fluid properties (thermal conductivity, density, specific heat, dynamic and kinematic viscosity, operating temperature and boiling point), in addition to the carbon-nanotube volume fraction. Using dimensional analysis, we constructed a set of π-groups and calibrated a regression-type model on 102 experimental data points gathered from the literature, and then assessed its accuracy against an independent set of 52 data points. Statistical indicators (mean absolute percentage error, signed mean error and standard deviation) demonstrate good agreement with measurements. Comparisons with widely used correlations further highlight the improved predictive capability of the present model, especially regarding the roles of carbon-nanotube length and diameter. Limitations: the current correlation does not explicitly incorporate nanofluid stability and aggregation metrics; thus, extrapo-lation beyond the calibration ranges should be made with caution. This correlation is suitable for engineering and numerical applications within the reported ranges.
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Authors and Affiliations

Farqad Rasheed Saeed
1
Hussein Fawzi Hussein
1
Natheer Basheer Mahmood
2

  1. Scientific Research Commission, Baghdad, Iraq
  2. Ministry of Education, General Directorate of Baghdad Education Karkh2, Baghdad, Iraq
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Abstract

In light of current energy policies, integrating renewable energy and waste heat recovery into district heating systems has become increasingly crucial. There is a particular need to identify locally available, low-temperature heat sources that can be effectively upgraded to meet the high supply temperatures required by existing networks. This study examines the technical and economic viability of high-temperature heat pumps utilising treated sewage as a renewable heat source in district heating systems. A comprehensive mathematical model of a high-capacity, two-stage centrifugal heat pump was developed and imple-mented in Aspen HYSYS to simulate its performance under varying operational conditions typical of Central-Eastern Europe. The model accounts for seasonal variations in sewage flow and temperature, as well as regulatory constraints of district heating networks and technical requirements such as temperature lift (ΔTlift) and part-load operation. Two operating scenarios are evaluated: a conventional coal-based system and a hybrid system incorporating a 3 MW sewage heat pump. Results indicate that the heat pump can meet domestic hot water demand in the summer and reduce annual CO2 equivalent emissions by ap-proximately 9500 tonnes, assuming the use of renewable electricity. Despite minor degradation in the coefficient of perfor-mance at part-load and low-flow conditions, the system demonstrated stable, efficient performance. An economic assessment using the levelised cost of heat method confirmed cost competitiveness in the Polish market context. The findings underscore the strategic role of sewage-source heat pumps in decarbonising urban heating.
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Authors and Affiliations

Aleksandra Dzido
1
Piotr Krawczyk
1
ORCID: ORCID
Adrián Mota-Babiloni
2

  1. Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw, Poland
  2. ISTENER Research Group, Department of Mechanical Engineering and Construction, Universidad Jaume I, Castellon de la Plana, E-12071, Spain
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Abstract

The increasing accumulation of biowaste in the environment, hence the need to investigate alternate energy sources has arisen due to the depletion of fossil fuel stocks. Eco-friendly, non-toxic, stable and biodegradable fuels with a high flash point and suitability for combustion are gaining attention. In this study, cottonseed biodiesel and pyrolytic oil were investigated as alternative fuels for compression ignition engines. Transesterification of cottonseed oil with sodium hydroxide as a catalyst and methyl alcohol as a reactant made biodiesel. Pyrolysis, a controlled thermal degradation process that is done in a safe environment, was used to make pyrolytic oil. A compression ignition engine was used to test the extracted biodiesel and pyrolytic oil after they were mixed with diesel in an 8:2 ratio. The performance and emission characteristics of ordinary diesel were compared with those of carbon monoxide, nitrogen oxides, hydrocarbons, smoke emissions, brake specific fuel con-sumption, brake thermal efficiency and other factors. The B20 blend showed 28.5% brake thermal efficiency, 0.32 kg/kWh brake specific fuel consumption, 22% lower CO, 19% lower HC, and 24% reduced smoke emissions than diesel, highlighting improved combustion and reduced emissions despite higher fuel consumption. According to the findings, cottonseed biodiesel is a suitable substitute fuel for compression ignition engines since it emits less CO and NOx.
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Authors and Affiliations

A. Manikandan
1
R. Thamizhvel
1
K. Kalaiselvan
1
ORCID: ORCID
S. Jassir Iqbal
1

  1. IFET College of Engineering, Villupuram 605108, Tamil Nadu, India
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Abstract

The current research explores experimentally the crude oil production from water hyacinth weed (potential renewable bio-mass), its biodiesel preparation and implication of SiO2 nanoparticles (25 ppm, 50 ppm, 75 ppm, 100 ppm) with biodiesel (fixed 20%) and diesel (fixed 80%) blends on the performance and emission parameters of a 4-S single cylinder diesel engine. Crude water hyacinth oil is produced through the chemical Soxhlet extraction technique, and its biodiesel is prepared by transesterification. Metal oxide oxygenated SiO2 nanoparticles are dispersed through ultrasonication in water hyacinth bio-diesel blends to improve their combustion quality and make them more efficient. Prepared fuel blends’ properties are exam-ined as per the standards of the American Society for Testing and Materials. The experiment reveals that crude water hyacinth oil has 85.6% biodiesel yield. Dispersion of SiO2 nanoparticles in WHB20 fuel decreases the brake specific fuel consumption by 12.61% and improves the brake thermal efficiency by 12.55% at a maximum load. HC and CO emissions are found to be decreased by 25.85% and 22.64%, respectively, whereas NOx and CO2 emissions are found to be increased by 45.85% and 10.87%, respectively, for WHB20SiO2100ppm compared to fossil diesel at a maximum load. Overall, research concludes that WHB20SiO2100ppm fuel is the best performer and suitable alternative for diesels without change in engine design.
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Authors and Affiliations

Maneesh Singh
1
Prashant Saini
1
Chandrakant Mishra
1
Saif Nawaz Ahmad
1

  1. Department of Mechanical Engineering, Madan Mohan Malaviya University of Technology, Gorakhpur 273010, Uttar Pradesh, India
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Abstract

Growing concerns over plastic pollution and fossil fuel depletion have driven research toward alternative fuels and engine optimisation strategies. The transition from fossil-based fuels to alternative fuels is imperative for reducing greenhouse gas emissions and addressing plastic waste. This study investigates the synergistic effects of injection pressure, ignition timing and exhaust gas recirculation on a single-cylinder diesel engine with modified piston bowl geometry using waste plastic oil-diesel blends. Waste plastic oil, derived via pyrolysis of municipal plastic waste, was blended with diesel in varying propor-tions (25–100%). Tests on engines were performed with varying injection pressures (200–500 bar), ignition timing (17°−23° before top dead centre) and exhaust gas recirculation rates (0–9%). Results reveal that the D25WP75 blend at 500 bar and 23° before top dead centre offers a peak brake thermal efficiency, minimum brake specific fuel consumption, and reduced emissions of CO, HC, NOx and smoke opacity. Optimal exhaust gas recirculation at 6% further reduced NOx. The maximum cylinder pressure and heat release rate are obtained at 73.02 bar and 52.66 J/deg. The improvement percentage in brake thermal efficiency at 500 bar for the D25WP75 blend compared with D100 is 10.8%, with a reduction in brake specific fuel consump-tion of 11.76%. It is also observed that NOx reduces by 5.46%, CO by 44%, HC by 8.82% and smoke by 35.38%. The combined impact of piston geometry modification and injection strategies improved combustion uniformity and emission control. The findings suggest that integrating fuel modification with combustion optimisation offers a viable pathway to cleaner diesel engine operation.
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Authors and Affiliations

Rajammagari Hussain Vali
1
Vemuri Sai Srikanth
2
Mohammad Mujtaba Ahmed
3
A. Gouse Peera
1
P. Srikar
4

  1. Department of Mechanical Engineering, Rajeev Gandhi Memorial College of Engineering and Technology, Nandyal 518501, Andhra Pradesh, India
  2. Department of Mechanical Engineering, MRCET, Hyderabad 500100, Telangana, India
  3. Department of Mechanical Engineering, MRECW, Hyderabad 500100, Telangana, India
  4. Deputy Registrar, Department of Mechanical Engineering, OP Jindal University, Punjipathra, Raigarh 496109, Chhattisgarh, India
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Abstract

Thermal management of microelectronics has become a major concern for the semiconductor industry, especially for high-power applications, due to the requirements of large computations in a smaller packing. Here in this work, spray/drop impact cooling of microelectronics (hot spot cooling) is studied, using a heat sink with novel nanotexture on the surface. The adherent nanotexture with highly porous architecture was fabricated with polymeric nanofibres obtained from supersonic solution blow-ing. The impacting drops on the superheated bare surface visibly bounced and escaped, exhibiting a Leidenfrost phenomenon, whereas, for the coated surface, complete suppression of the Leidenfrost effect was observed. For a nanotextured surface, the impacting droplet was focused hydrodynamically to penetrate the porous layer and wick through the network, thereby getting pinned, despite the fibrous architecture being hydrophobic. The overall heat transfer rate was measured to be in excess of 1000 kW/m2 from the coated surface, as calculated from the wetting area. Later, it was also found that a drop interval time of 2.5 s yielded the optimised cooling for both short- and long-time applications. The long-time heating and cooling cycles ex-hibited a repeatable cooling pattern between the upper critical (130oC) and lower safe (80oC) range, demonstrating the excellent robustness of the nanofibrous texture and a possible route of preservation of coolant.
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Authors and Affiliations

Ravi Pippala
1
Aditi Agrawal
1
Akshitaa Akshitaa
1
Tulip Biswas
1
Deepali Deepali
1
Pushpendra Kumar Shukla
1
Sumit Sinha-Ray
2

  1. Department of Textile and Fibre Engineering, Indian Institute of Technology - Delhi, Hauz Khas, New Delhi 110016, India
  2. Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607-7022, USA
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Abstract

Growing demand for electricity and the intensification of the use of renewable energy sources create the need for the development of energy technologies, including hydrogen-based solutions. In the context of generating energy from hydro-gen, fuel cells are characterised by particularly favourable operating parameters. The literature identifies several types of fuel cells, among which high-temperature solid oxide fuel cells (SOFCs) show significant application potential. This is related, among other factors, to the possibility of integrating these cells into hybrid energy systems (fuel cell − gas cycle − steam cycle) with various configurations and high energy efficiency. To determine the optimal structures of hybrid systems, detailed system analyses are essential, requiring accurate modelling of fuel cell characteristics. Depending on the objective of the analyses, the cell models may vary in complexity. This paper presents an advanced one-dimensional fuel cell model, enabling more realistic preliminary thermodynamic and economic analyses of hybrid systems. This model facilitates the assessment of efficiency, dimensions and exhaust media parameters. Furthermore, it allows for the verification of whether the cell parameters used in the analyses align with their practical implementation capabilities.
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Authors and Affiliations

Julian Piotr Jędrzejewski
1 2
Sebastian Lepszy
1
Sebastian Rulik
1

  1. Silesian University of Technology, Faculty of Energy and Environmental Engineering, Konarskiego 18, 44-100 Gliwice, Poland
  2. Antea Polska S.A., Dulęby 5, 40-833 Katowice, Poland
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Abstract

This work presents the results of an experimental study on a 1 kW scroll expander in an organic Rankine cycle (ORC) system. The low-boiling, non-flammable hydrofluoroether HFE-7100, was used as the working fluid. The research was conducted at heat source power levels ranging from 10 kWt to 18 kWt. The flow rate of the working medium was in the range of 30 g/s to 60 g/s. The generator of the expansion unit, on the other hand, was loaded with electrical receivers, with a load ranging from 200 We to 2000 We. The study shows that, for the same working fluid flow rate and expander rotational speed, an increase in the thermal power of the heat source resulted in higher voltage at the generator terminals and increased electrical output power of the ORC system. It was found that, regardless of the HFE-7100 flow rate, the inclination angles of the electrical power and voltage curves with respect to the expander’s rotational speed axis increased as the thermal power of the heat source increased. Thus, for each level of a thermal power, there is an optimum generator load at which the electrical output power of the system is maximised. The research conducted shows that the maximum electrical output of 635 We was obtained for a heat source power of 16 kWt and a fluid flow rate of 60 g/s. In addition, it was found that for the tested ranges of heat source power and HFE-7100 flow rate, the optimum load for the expander generator was between 3.5  and 4.8 .
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Authors and Affiliations

Tomasz Zygmunt Kaczmarczyk
1

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

The studying and analysis of the nuclear abnormal conditions have become an important demand to achieve highly safety standards in the nuclear reactors (research or power), where the nuclear accidents have been a serious concern since the con-struction of the first nuclear reactor in 1954 and after the world faced some major nuclear accidents as Three Mile Island in 1979, Chernobyl in 1986 and Fukushima in 2011. This paper aims to analyse a failure in the natural circulation core cooling system that could lead to temperature rise during shutdown regime. According to this scenario, our study suggests a solution that involves the addition of a small pump to the core cooling circuit in case of flapper valve malfunction due to any reason. This potential scenario is applied theoretically in the ETRR-2 (Egyptian Testing and Research Reactor Number 2). The RELAP5-3D simulation code is used to simulate and model the thermal behaviour of the core condition during this abnormal scenario and to evaluate the proposed solutions. The proposed emergency pump may be designed and estimated to permit opening flapper valve as well. This approach resolves the issue of flapper valves malfunction, which makes the reactor shut-down safe.
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Authors and Affiliations

Hesham Hassanin ElKhatib
1
Asmaa Abo Elnoura
1
Ahmed Ramadan
1
Said Kotb
1
Magdy Zaky
2
Samy Dwidar
1

  1. Egyptian Atomic Energy Authority, Nuclear Reactor Department, Inshas, Cairo 13759, Egypt
  2. Egyptian Atomic Energy Authority, Engineering and Scientific Instruments Department, Inshas, Cairo 13759, Egypt
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Abstract

The increasing demand for electricity and cooling, resulting from accelerating urban growth, growing economies and the integration of technology into daily life, leads to continued research and study of theories related to the optimal exploitation of energy sources, including those with low temperatures, for a sustainable environment free of CO2. The authors regard the Kalina cycle, which uses ammonia and water as its working fluid, as the most efficient system in this field. This manuscript presents a comprehensive review of the published literature on the modified Kalina cycle, a cogeneration system that simulta-neously produces electricity and cooling. It also provides an overview of the original Kalina cycle, other types of Kalina cycles, and their various applications. We also discuss the properties of the binary solution, which the cycle uses as a working fluid. Discuss the boiling and freezing points to maintain the fluidity of the working fluid through the cooling process. Additionally, we discuss the corrosion-related aspects of applying the Kalina cycle, specifically the reaction between ammonia and metal components, as well as strategies for mitigating this corrosion, as previously mentioned in the literature.
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Authors and Affiliations

Mohammed Wahody Eraiby
1
Abdulkhodor Kathum Nassir
1

  1. College of Engineering, Mechanical Engineering Department, University of Babylon, Babylon City 51001, Hilla, Iraq
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Abstract

This article investigates the parametric effects on heat transfer in cross-flow heat exchangers integrated with a backward splitter plate to enhance the coefficient of performance in a solar assisted vapour absorption refrigeration system. The system replaces conventional electric energy with solar energy, utilising a solar energy collector to heat water between 50 − 80°C. This heated water vaporises aqueous ammonia in a generator designed as a double pipe heat exchanger. The primary objective is to facilitate efficient heat transfer from the solar energy collector to the solar assisted vapour absorption refrigeration system and evaluate the cooling performance at varying water mass flow rates. Computational fluid dynamics has been used to solve the governing equations under appropriate boundary conditions. While second-order discretisation has been used for momen-tum and energy equations, coupled equations have been used to address velocity and pressure coupling. Convergence criteria of 10⁻⁶ for velocity and continuity, and 10⁻⁸ for energy, were employed. Thermal modelling was conducted to find out com-ponent-specific heat transfer rates and estimate the cumulative coefficient of performance. A small-capacity (1.5 ton or 5.25 kW) solar vapour absorption cooling system was tested. The study found that increasing the L/D ratio enhances heat transfer; for instance, at Re = 12000 and L/D = 2, the Nusselt number increased by 90% compared to Re = 2000. However, the pressure dropped significantly at L/D = 3, suggesting an optimal design trade-off. Additionally, the impact of key param-eters such as absorber, condenser, generator and evaporator temperatures on the system’s coefficient of performance was thoroughly analysed.
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Authors and Affiliations

Sachin Kaushik
1
Subash Chandra Ram
2
Chandra Kishor
3
Sunil Chamoli
1

  1. Department of Mechanical Engineering, Graphic Era University, Dehradun 248002, Uttarakhand, India
  2. Department of Mechanical Engineering, Tula’s Institute, Dehradun 248011, Uttarakhand, India
  3. Department of Mechanical Engineering, GBPIET, Pauri, Garhwal 246194, Uttarakhand, India
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Abstract

The collective influence of slip and asymmetric heating is of great importance in many industries involving micro and macro-scale thermal systems, as it is directly related to flow resistance, thermal gradients and entropy generation. These effects are particularly relevant in channels with immiscible fluids, where wall fluid interactions and spatially varying boundary conditions govern the overall transfer behaviour. So the novelty of this work is a numerical analysis of entropy generation and heat and mass transfer in a vertical channel filled with two immiscible fluids, under a non-uniform heat, along with the influence of velocity slip. The system of governing equations of momentum, energy and diffusion is made non-dimensional using relevant variables, and then solved numerically using the Runge-Kutta method. The momentum, temperature and diffusion variations are presented in a graphical mode using data visualisation and smoothing via interpolation in Python for better visibility of the variations. The momentum, heat and mass transfer rates on both plates of the channel are also made non-dimensional. The other important parameter, entropy, is also calculated in the defined domain, and the obtained values are tabulated. The study found that all parameters, including slip effect, have a significant impact. In particular, the temperature, entropy generation and velocity are strongly affected by buoyancy forces and magnetic fields. The increase in Grashof number and molecular Grashof number improves fluid motion and reduces entropy. Both the increasing Reynolds number and magnetic parameter contribute to an increase in entropy generation. Shear stress analysis reveals two flow layers affected by buoyancy and magnetic damping.
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Authors and Affiliations

Santhosh Kasula
1
M.N. Raja Shekar
2

  1. Sreyas Institute of Engineering and Technology, Hyderabad 500068, Telangana, India
  2. JNTUH University College of Engineering Science and Technology, Hyderabad 500068, Telangana, India
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Abstract

In order to accurately predict the energy consumption and design energy-saving retrofits for office buildings, this study proposes a climate adaptation-based energy consumption prediction method by combining depthwise separable convolu-tion and frequency-guided two-dimensional tensorisation algorithm. A multi-objective optimisation retrofit design model is then constructed using the non-dominated sorting genetic algorithm III and ideal point method. Experimental results show that the prediction method achieves the highest accuracy of 96.3% and the lowest error rate of 5.9% under various climate conditions, outperforming comparison algorithms. In practical applications, the retrofit design model responds in as little as 7.3 s and consumes a minimum memory of 189 MB. With a 30% increase in electricity prices, the payback period is only 6.05 years, and the carbon reduction rates for air conditioning and lighting are 59.9% and 58.6%, respec-tively. The results indicate that the proposed model provides a design solution with high prediction accuracy, robustness and cost-effectiveness, improving the feasibility of office buildings' low-carbon transformation.
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Authors and Affiliations

Yining Shen
1

  1. Department of Architecture Engineering, Shijiazhuang College of Applied Technology, 226/227 Tianning Road, Shijiazhuang 050800, China
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Abstract

Experimental research, especially physical modelling, is vital when direct study of real systems is impractical. By applying similarity theory and dimensionless variables, models allow reliable analysis of results. While experiments alone are often qualitative and time‑consuming, combining them with theoretical modelling yields stronger quantitative insights. Careful planning, computer-based data collection, and awareness of measurement errors ensure precision and efficiency. The theory of similarity defines the criteria under which the behaviour of a model can be considered representative of the real system. By satisfying these criteria, experimental results obtained from the model can be reliably extrapolated to the actual phenom-enon. The present paper aims to present Authors’ up-to-date experiences in advanced research using scaled models based on similitude theory, ever since its establishment as a branch of the engineering science to convince the reader about the benefits of physical modelling in comparison to advanced computer based methods governing the contemporary research.
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Authors and Affiliations

Jarosław Mikielewicz
1
Dariusz Mikielewicz
2

  1. Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, Gdańsk 80-231, Poland
  2. Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk, Poland
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Abstract

This paper presents the development of a novel experimental device for measuring the thermal conductivities of both non-conductive and conductive solids under transient conditions. The device comprises a sensor assembly coupled with an elec-tronic bridge circuit and a direct current power source. The developed device was successfully used to measure the thermal conductivity of non-conducting and conducting solids, specifically granite and stainless steel 304, at room temperature. The device was also extended to two additional non-conducting solids, namely, limestone and basalt, to validate the testing. The thermal conductivities of granite, stainless steel-304, limestone and basalt were 2.14 W/(m·K), 14.93 W/(m·K), 2.91 W/(m·K), and 2.72 W/(m·K), respectively. These findings demonstrate excellent concordance with the existing literature for both non-conducting and conducting solid materials. The standard uncertainty of the developed device was ± 4.2%. The entire measure-ment process takes less than 5 s.
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Authors and Affiliations

M. S. Karthika
1
Mangalpady Aruna
2
P. Siva Kota Reddy
3 4

  1. Department of Mechanical Engineering, JSS Science and Technology University, Mysuru 570 006, Karnataka, India
  2. Department of Mining Engineering, National Institute of Technology, Karnataka, Surathkal, Mangalore 575 025, Karnataka, India
  3. Department of Mathematics, JSS Science and Technology University, Mysuru 570 006, Karnataka, India
  4. Universidad Bernardo O'Higgins, Facultad de Ingeniería, Ciencia y Tecnología, Departamento de Formación y Desarrollo Científico en Ingeniería, Av. Viel 1497, Santiago, Chile
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Abstract

Given the global energy crises and severe climate challenges, it is urgent to develop zero-energy anti-icing technologies to ensure infrastructure security. Bio-based aerogels, due to their environmental friendliness and renewable characteristics, excellent thermal insulation properties and structural design flexibility, provide an innovative opportunity for solar-pow-ered intelligent thermal management. Therefore, we systematically review recent developments in bio-based aerogels for intelligent thermal management. The concept of ‘localisation of solar thermal energy’ is proposed to highlight a paradigm shift from passive insulation to active thermal management platforms. Through a critical analysis of green interface cou-pling, biomimetic anisotropic structures and photothermal-phase transition sequences, the importance of rational cross-scale design in overcoming performance barriers (such as high porosity, high strength, low thermal conductivity and high photothermal efficiency) is emphasised. In addition, research gaps in dynamic energy matching, environmental durability and system integration are identified, providing a theoretical framework and development path for designing future intel-ligent anti-icing materials. This review demonstrates that through integrated multi-scale design, bio-based aerogels can achieve a surface temperature increase of over 60°C under 1 solar irradiance, and maintain the bulk thermal conductivity below 0.025 W/(m K). This finding indicates a promising approach to achieving zero-energy anti-icing solutions.
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Authors and Affiliations

Jincheng Su
1 2 3
Jiliang Wang
2
Wei Zhou
3
Xiaozhuang Yang
1
Qinghua Miao
1
Bing Wang
1
ORCID: ORCID

  1. Harbin University of Commerce, School of Energy and Civil Engineering, Xuehai 1, Songbei District, Harbin Heilongjiang 150028, China
  2. Heilongjiang Province Academy of Cold Area Building Research, Qingbin Road 60, Nangang District, Harbin Heilongjiang 150080, China
  3. Harbin Institute of Technology, School of Civil Engineering, Xidazhi 92, Nangang District, Harbin Heilongjiang 150001, China
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Abstract

A novel power-cooling system triggered by low-grade thermal energy is proposed and studied in this paper. The power-cooling unit combined the engine (organic Rankine cycle) and cooler (ejector-expansion refrigeration cycle employing a booster). Both cycles employ isobutene (R600a) as a working fluid and share a single condenser unit. The performance characteristics (overall coefficient of performance and working fluid mass flow rate per kW of cooling capacity) of the novel unit was investigated using thermodynamic analysis in comparison to the traditional unit that is commonly used. The latter combines the engine (organic Rankine cycle) with the cooler (vapour compression refrigeration cycle) in various operational conditions, including exit temperatures of a boiler unit (60−90°C), a condenser unit (30−55°C) and an evapo-rator unit (15−15°C). It was discovered that in comparison to the traditional unit, the novel unit exhibited lower working fluid mass flow rate per kW of cooling capacity and higher overall coefficient of performance. The overall coefficients of performance for both systems increase by 0.5385 and 0.4476, respectively, when the boiler unit’s temperature reaches 90°C and the other input specifications are set to typical values. On the other hand, the working fluid mass flow rate per kW cooling capacity of both systems drops by 0.0096 and 0.0064, respectively. Overall, the study demonstrates that the novel system triggered by low-grade thermal energy can be an alternative to the traditional system.
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Authors and Affiliations

Youcef Maalem
1
Hakim Madani
2

  1. Ecole Nationale Polytechnique de Constantine, BP 75, A, Nouvelle ville RP, 25000 Constantine, Algeria
  2. University of Batna 2, Faculty of Technology, Department of Mechanical Engineering, Rue Chahid Boukhlouf M. El Hadi, 05000 Batna, Algeria

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• contact address and telephone numbers of the corresponding author.

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 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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