Nauki Techniczne

Archives of Thermodynamics

Zawartość

Archives of Thermodynamics | 2025 | vol. 46 | No 3

Abstrakt

The increasing share of renewable energy production in energy markets has resulted in the demand for more flexible operation of conventional power plants. Coal-fired units are forced to operate in a more cyclic duty with a higher number of starts, faster start-ups and increased load change rates. These unfavourable operating conditions result in additional thermal loading of steam turbine components and necessitate better monitoring of life-limiting components. The paper presents numerical investigations of thermal loading of a steam turbine valve at various operating conditions and identifies the requirements for an online monitoring method. A modified method based on Duhamel’s integral is proposed and validated at different transient conditions, taking into account both convection and condensation heat transfer. It was shown that the calculation method provides reasonably accurate predictions of casing wall temperature. Relative differences between measured and calculated wall temperatures are within (−2.6%)–(+1.5%) for the investigated start-ups with condensation and convection heat transfer conditions. Advantages of this method and its suitability for online monitoring of thermal loads of steam turbine components are discussed in detail.
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Autorzy i Afiliacje

M. Banaszkiewicz
1

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

Abstrakt

In the contemporary energy landscape, governments are focusing on improving the efficiency of electricity generation and promoting distributed energy systems based on local and renewable sources. This has led to a substantial increase in the number of prosumer, polygeneration, and microgeneration power plants currently under development. In the case of micro-power plants, often turbine-based, particular emphasis is placed on the durability, reliability, cost-effectiveness, and efficiency of both individual components and the entire system. The construction of microturbine power plants involves several challenges, including component miniaturisation, achieving extremely high rotational speeds, efficient power transmission, maintaining adequate safety standards, reducing noise, minimising emissions of harmful compounds, and designing the electric generator. Additional difficulties concern the optimisation of thermodynamic and fluid-dynamic processes, the high-efficiency design of flow components, ensuring bearing and dynamic stability in high-speed rotating systems, miniaturising heat exchangers, and enhancing thermal processes. Despite the availability of commercial microturbine solutions, recent years have seen intensified research and development efforts. The evolution observed in this field suggests that efforts to improve efficiency, durability, reliability, and cost-effectiveness will continue, strongly supported by government involvement. Current progress and accumulated experience have enabled the development of engineering calculation methods for microturbine design, a crucial element of microgrids. This paper reviews the existing literature on microturbines, with particular attention to experimental results and examples of practical designs. It also outlines the main challenges faced by designers and engineers in developing such systems.
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Autorzy i Afiliacje

K. Kosowski
1
M. Piwowarski
1
R. Stępień
2
W. Włodarski
1

  1. Faculty of Mechanical Engineering and Ship Technology, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
  2. Proturb, Poland, Fiszera 14/513, 80-231 Gdansk, Poland

Abstrakt

The paper discusses tests of an electric capacitance sensor designed and built to measure gas fraction in a reservoir fluid flow. These tests were conducted under conditions typical for oil field testing and productivity monitoring. In such an application, the electrical permittivity of the liquid and gas components is of the same order of magnitude, which poses a significant challenge in capacitance metering of the phase content. The studied two-electrode capacitance sensor is a novel design. It uses a commercial, high-resolution ΔΣ capacitance-to-digital converter. The sensor was experimentally tested on the flow of reser-voir fluid (from Lubiatów-Międzychód-Grotów field in Poland) heated to 40–50°C to reproduce field conditions during actual gas and oil extraction. The gas fraction in the reservoir fluid was generated by the injection of air or methane bubbles. Fluid velocities during the testing ranged from 1 to 3.1 m/s, and the void fraction reached 4.4%. After calibration, the examined capacitance sensor was able to detect a void fraction as low as 1%. The measured capacitance differences due to gas content were dependent on the spatial distribution of voids in the inter-electrode space. This effect was confirmed by photographs of the flow patterns and numerical simulations of the electric field distributions.
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Autorzy i Afiliacje

Remigiusz Ornowski
1 2
Stanisław Żwan
1

  1. TERCJA Measuring and Computer Systems, Dywizjonu 303 5B/24, 80-462 Gdańsk, Poland
  2. Institute of Fluid Flow Machinery, Polish Academy of Sciences, ul. Fiszera 14, 80-231 Gdańsk, Poland

Abstrakt

Our proposed model is a highly non-linear parabolic heat transfer equation for the longitudinal fin with an insulated fin tip, temperature dependent thermal conductivity, and internal heat generation in the transient condition. The research comprises several components, namely, a discussion of the longitudinal fin heat transfer model, its solution, the validation of the numer-ical scheme and solution analysis, and finally, the influence of fin attachment on the system. Mathematical formulations were developed to represent identified fin parameters. This enables us to investigate further their variation patterns, therefore mak-ing future modelling easy as well as providing a better understanding of their applicability in developing energy storage sys-tems
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Autorzy i Afiliacje

Ishita Rai
1
Rajeev Kumar
1

  1. Birla Institute of Technology, Mesra 835215, India

Abstrakt

The consequences of magnetohydrodynamic mixed convection in a trapezoidal heat exchanger are investigated through numerical analysis. Due to the extensive applications of both mono and hybrid nanofluids in manufacturing and thermal engineering, the Ag-MgO-H2O hybrid nanofluid is selected as the working material for the entire domain. Additionally, a horizontal magnetic field is applied to the cavity. The finite element method is involved to solve the corresponding mathematical equations. The physical implications of the results are examined over a range of Reynolds numbers (10 ≤ Re ≤ 200), Hartmann numbers (0 ≤ Ha ≤ 100), and nanoparticle volume fractions (0 ≤ ϕ ≤ 0.08) using streamlines, isotherms, and line graphs. The impact of key factors on the response function is illustrated using the response surface methodology with 2D and 3D visualizations. Sensitivity rates are analysed by developing a best-fit correlation. It is concluded that the thermal enhancement of the hybrid nanofluid is achieved up to 11.4% by incorporating hybrid nanoparticles, and due to the upsurge of the Reynolds number. Conversely, the influence of the magnetic field leads to a decline in this rate to 10.02%. The use of Ag-MgO-H2O hybrid nanofluid improves the heat transfer efficiency of water by 6.62%. Finally, the results of this study may offer valuable insights for designing an efficient mixed convective mechanical device
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Autorzy i Afiliacje

Saiful Islam
1
Goni Molla
2
Badhan Neogi
1
Muhammad Faiaz
1
B.M. Jewel Rana
3
Md. Mamun Molla
4 5

  1. Department of Mathematics, Gopalganj Science and Technology University, Gopalganj 8100, Bangladesh
  2. Department of Applied Physics, Electronics & Communication Engineering, Gopalganj Science and Technology University, Gopalganj 8100, Bangladesh
  3. Department of Quantitative Sciences (Mathematics), International University of Business Agriculture and Technology, Dhaka 1230, Bangladesh
  4. Department of Mathematics & Physics, North South University, Dhaka 1229, Bangladesh
  5. Center for Applied and Computational Sciences (CACS), North South University, Dhaka 1229, Bangladesh

Abstrakt

This study presents a novel investigation into the boundary layer flow, heat, and mass transfer of a Newtonian, incom-pressible and electrically conducting viscous fluid flow past a permeable curved stretching surface embedded in porous media with Soret and Dufour effects subject to varying magnetic fields and thermal slip. The research uniquely combines these complex phenomena, addressing a significant gap in the literature. This configuration has potential applications in electronic cooling systems, polymer manufacturing and compact heat exchangers in various industries. The main objectives are to understand how various parameters influence fluid flow, heat and mass transfer behaviour to optimize the design for enhanced performance. To attain the numerical results the governing equations are transformed into to a set of nonlinear ordinary differential equations, which are then solved numerically by using MATLAB’s built-in solver bvp4c. The param-eters of engineering interest are tabulated and validated with previous results. The outcomes of the study suggest that the presence of a larger magnetic parameter, Dufour number, Joule parameter, thermal slip and curvature parameter contribute to reducing the cooling rate of the system by 2.73%, 10.53%, 12.39%, 9.29% and 6.28%, respectively. Also, the curvature of the surface can be enlarged from 5 to 10 to obtain 6.87% reduction in surface drag force.
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Autorzy i Afiliacje

Temjennaro Jamir
1
Hemanta Konwar
2
Bendangwapang Tzudir
2

  1. Phek Government College, Phek, Phek 797108, India
  2. Kohima Science College, Jotsoma, Kohima 797001, India

Abstrakt

Nanofluids have garnered significant interest in various fields due to their numerous advantages and potential applications. The appeal of ethylene glycol (EG)-based Cu-nanofluid lies in its excellent thermal conductivity, stability, and ability to enhance heat transfer properties, making it a promising candidate for diverse industrial applications. In this study, we analyse the flow behaviour of EG-based copper (Cu) nanofluid over a nonlinear stretching surface under the influence of Joule heating effects. The research involves the development of a mathematical model and formulating of governing equa-tions represented as system of partial differential equations, which are subsequently transformed into nonlinear ordinary differential equations through suitable transformations. A numerical framework based on MATLAB bvp4c solver tech-nique is employed to obtain approximate solutions. The study examines the influence of dimensionless parameters on velocity and thermal distributions. The findings for the local Nusselt number and skin friction are presented in tabular form, highlighting the effects of key parameters. The results are benchmarked against three different sources from existing liter-ature, showing strong agreement in the case of reduced Nusselt number.
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Autorzy i Afiliacje

Ramzan Ali
1
Ainura Mitalipova
2
Syed Wajeeh Ul Hussan
3
Abdikerim Kurbanaliev
2
Azeem Shahzad
3
Mukhammadmuso Abduzhabbarov
4

  1. University of Doha for Science and Technology, 68 Al Tarafa, Jelaiah Street, Duhail North, 24449, Doha, Qatar
  2. Osh State University Kyrgyz Republic, Lenina Street 331, 714000, Kyrgyzstan
  3. University of Engineering and Technology, Department of Mathematics, Faculty of Basic Sciences, Taxila, HMC Link Rd, Taxila, 47050, Pakistan
  4. Westminster International University in Tashkent, School of Law, Technology & Education, Istiqbol 12, Tashkent, 100047, Uzbekistan

Abstrakt

The necessity of providing fresh water to the existing population has remained a significant challenge, highlighting the utmost necessity of a sustainable water purification technique. Therefore, the present review article investigates the recent developments in paraffin wax-based enhancements for solar stills for improving freshwater yield. Paraffin wax, a widely used phase change material (PCM), offers high latent heat storage and chemical stability; however, its low thermal conductivity and long-term reliability present significant challenges. Therefore, this article aims to provide sufficient knowledge on the most practical designs of solar still with paraffin wax. Also, the review highlights design modifications, placement strategies, nanoparticle incorporation, and external attachments like heat exchangers and collectors that have been employed to enhance distillate yield. Economic analyses indicate that paraffin-enhanced systems offer lower water production costs compared to conventional solar stills. Challenges such as phase segregation, volumetric expansion, and material degradation over repeated cycles are discussed. This review aims to provide a comprehensive understanding of optimizing solar still performance using paraffin wax, supporting future research and practical implementation for sustainable water desalination. The key findings indicate that pyramid-shaped solar stills are the most suitable design and their integration with paraffin wax can significantly improve the distillate yield by 100 %.
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Autorzy i Afiliacje

Akashdeep Negi
1
Lalit Ranakoti
1
Sandip Kumar Mishra
2
Rajesh Prasad Verma
3
Vineet Kumar
1
Adhirath Mandal
4
Prabhakar Bhandari
5
Arun Uniyal
6
Prabhakar Zainith
7

  1. Department of Mechanical Engineering, Graphic Era Deemed to be University, Dehradun, 248002, India
  2. Mechanical Engineering Department, Bundelkhand University, Jhansi, 284128, Uttar Pradesh, India
  3. GL Bajaj Institute of Technology and Management, Greater Noida, Uttar Pradesh, 201306, India
  4. Department of Mechanical Engineering & Design, Jaypee Institute of Information Technology, Noida, 201309, Uttar Pradesh, India
  5. Mechanical Engineering Department, School of Engineering and Technology, K.R. Mangalam University, Gurugram, 122103, Haryana, India
  6. Department of Mechanical Engineering, COER University, Roorkee, 247667, Uttarakhand, India
  7. Department of Mechanical Engineering, Shivalik College of Engineering, Dehradun, 248197, Uttarakhand, India

Abstrakt

This study presents a novel, cost-effective multigeneration system configuration that utilises locally available solar irradiance and biomass resources to produce hydrogen, electricity, heating, hot water, and cooling. The system integrates a range of energy conversion technologies, including non-conventional parabolic trough collectors, conventional biomass gasification, the Kalina cycle, organic Rankine cycle, vapour absorption system, an electrolyser, and a fuel cell. A thermoeconomic analysis was conducted to evaluate system performance, with exergy-based costing applied to determine the operating costs while optimising overall net output. The study also assessed the exergetic sustainability of the system by analysing thermodynamic inefficiencies. It was found that an optimal ambient temperature of approximately 297.4 K maximises the system's exergetic sustainability index, reaching a value of 1.00. The levelized cost of electricity from the Kalina and organic Rankine cycle subsystems was calculated as 0.04308 USD/kWh and 0.0245 USD/kWh, respectively, corresponding to an exergoeconomic factor of 44.51%. When converted to Nigerian currency, these values equate to 69.12 NGN/kWh and 39.31 NGN/kWh − significantly lower than the prevailing electricity tariff in Nigeria, which stands at approximately 209.50 NGN/kWh (0.1306 USD/kWh). Under specified operating conditions, the optimal work outputs of the organic Rankine cycle and Kalina cycle turbines were 47.97 kJ/kg and 435.3 kJ/kg, respectively. The overall energy and exergy efficiencies of the integrated plant were recorded at 52.2% and 16.14%. This multigeneration system demonstrates strong potential as an alternative to fossilfuel- based power generation, particularly in applications and sectors with low energy demand.
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Autorzy i Afiliacje

Obiora Emeka Anisiji
1 2
Ikuobase Emovon
Olusegun David Samuel
2
Fidelis Abam
3

  1. Department of Mechanical and Mechatronics Engineering, Federal University Otuoke, P.M.B. 126, Yenagoa, Nigeria
  2. Department of Mechanical Engineering, Federal University of Petroleum Resources Effurun, P.M.B. 1221, Effurun, Nigeria
  3. Department of Mechanical Engineering, University of Calabar, P.M.B. 1115, Calabar, Nigeria

Abstrakt

This study investigates the potential of machine learning models as efficient alternatives to traditional computational meth-ods for evaluating the performance of earth-air heat exchanger systems. A validated numerical model was used to simulate system behaviour under varying parameters, including soil type, pipe material, number of internal twisted tabs and outlet temperature. Based on these simulations, a dataset comprising 216 entries was generated to train three machine learning models: support vector regression, gradient boosting and decision trees. The gradient boosting model achieved the highest predictive accuracy, with a root mean square error of 0.0188 and a mean absolute error of 0.0138. Support vector regression and decision trees also demonstrated strong performance, with prediction accuracies of 97% and 96%, respectively. Addi-tionally, the proposed earth-air heat exchanger design with twisted tabs showed superior thermal performance compared to the conventional configuration. Over extended operation, the temperature difference between inlet and outlet exceeded 7°C, with the new configuration system incorporating 10 tabs yielding optimal performance. This configuration led to more than a 10% improvement in thermal efficiency and an increase of approximately 25% in the heat transfer coefficient. These results confirm that integrating machine learning with advanced earth-air heat exchanger designs offers a reliable and computationally efficient approach for enhancing system performance.
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Autorzy i Afiliacje

Fatima Benali Kouchih
1
Khadidja Boualem
1
Malika Seddik Bouchouicha
1
Yasmine Bentouba
1
Abdhalim Soussa
1
Abbes Azzi
1

  1. Aero Hydrodynamic Naval Laboratory (LAHN), University of Science and Technology of Oran Mohamed Boudiaf (USTO-MB), Faculty of Mechanical Engineering, BP1505 El-Mnaouar, Oran 31000, Algeria

Abstrakt

The paper focuses on the design of the geometry and operational parameters of a cyclone separator. Its main objective is to identify a combination of dimensional and flow parameters that enables the efficient capture of large particles containing carbon and iron, while allowing particles rich in zinc and lead to pass through. The cyclone separator is intended to separate dust with a high content of valuable materials so that it can be reprocessed in a blast furnace. A computational fluid dy-namics model, previously validated against similar datasets, is employed to support the design process. Three different geometries and inlet velocities ranging from 2 m/s to 12 m/s were tested to determine the most effective configuration. Depending on the selected parameters, the overall separation efficiency varied between 46% and 93%. Specifically, the system achieved separation efficiencies of 60–95% for carbon, 38–90% for iron, and 14–67% for zinc. The final design reached an overall efficiency of 86.5%, successfully separating over 90% of carbon, more than 80% of iron, as well as 45% of zinc and 55% of lead.
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Autorzy i Afiliacje

Arkadiusz Ryfa
1
Mieszko Tokarski
1 2
Wojciech Adamczyk
1
Adam Klimanek
1
Paweł Bargiel
1
Ryszard Białecki
1
Michał Kocot
3
Marian Niesler
4
Harald Kania
4
Janusz Stecko
4
Marianna Czaplicka
4
ORCID: ORCID

  1. Department of Thermal Technology, Silesian University of Technology, Konarskiego 22, Gliwice 44-100, Poland
  2. Department of Fuels Technology, AGH University of Science and Technology, Czarnowiejska 30, Kraków 30-059, Poland
  3. ArcelorMittal Poland, al. Piłsudkiego 92, Dąbrowa Górnicza 41-308, Poland
  4. Łukasiewicz Research Network – Upper Silesian Institute of Technology, Karola Miarki 1214, Gliwice 44-100, Poland

Abstrakt

Quenching and tempering processes are commonly employed to enhance the physical and mechanical properties of multiphase steels. This study investigated the effects of heat treatment on ASTM A36 low-carbon steel, a material well-suited for structural applications. The novelty of this study lies in the detailed investigation of the quenching and tempering processes applied to ASTM A36 low-carbon steel, focusing on specific tempering temperatures and varying soaking times. The specimens were heated to 900°C and soaked for 2 hours, followed by quenching in an oil bath. Subsequently, they were tempered at low (200°C), medium (300°C), and high (400°C) temperatures for 60, 90, and 120 minutes, respectively. The mechanical properties of the processed specimens, including hardness, tensile strength, and impact strength, were evaluated. The Rockwell hardness showed a significant improvement of 22.75% after treatment. Oil bath quenching followed by tempering increased the ultimate tensile strength by 31.51% and 29.36%, respectively, compared to steel without any heat treatment. However, elongation at break and impact strength decreased by 11.55% and 27.27%, respectively, during quenching. Low, medium, and high temperature tempering at various soak-ing times released the internal stresses, refined the grain structure and exhibited the effect on tensile strength, as well as improved the elongation at break and impact strength by 35.08% and 125%, respectively, compared to quenched steel.
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Autorzy i Afiliacje

Anant Prakash Agrawal
1
Shahazad Ali
1
Virendra Kumar
2
ORCID: ORCID
Pallav Gupta
2

  1. Mechanical Engineering Department, Noida Institute of Engineering and Technology, Greater Noida, 201306, India
  2. Mechanical Engineering Department, Madan Mohan Malaviya University of Technology, Gorakhpur, 273010, India

Abstrakt

This study uniquely investigates cotton seed oil as a biodiesel source, a less-explored feedstock, and evaluates the role of TiO2 nanoparticles in enhancing performance and emission characteristics. The use of a variable compression ratio engine under diverse load conditions further distinguishes this work from existing studies on nanoparticle-blended biofuels. The biodiesel was produced via transesterification and blended at various proportions, with and without TiO2 additives. Experi-mental tests were conducted on a variable compression ratio diesel engine under varying load conditions: one-fourth, half, three-fourths, and full load. The results were compared against conventional diesel fuel. Among the tested blends, B40 (40% biodiesel, 60% diesel) without TiO2 exhibited the highest brake thermal efficiency, exceeding that of diesel by 5.4%, and achieved the highest mechanical efficiency (58.31%) at full load condition. Fuel consumption increased proportionally with load across all fuel types. Notably, B40 without TiO2 also recorded the lowest hydrocarbon emissions, with a reduction of 34 ppm at full load, which corresponds to a 45% decrease compared to conventional diesel. Carbon monoxide emissions were effectively eliminated in TiO2-blended fuels due to improved combustion. Additionally, nitrogen oxides emissions were reduced by 1.1% in B40 when TiO2 was incorporated. Overall, the findings highlight that cotton seed biodiesel, particularly when enhanced with TiO2 nanoparticles, can offer substantial improvements in engine performance and emission control compared to conventional diesel.
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Autorzy i Afiliacje

Santhosh Kumar Dubba
1 2
Raminaidu Pisini
1
Durgaprasad Kelli
1
Roopsandeep Bammidi
1
Jaya Prasad Vanam
3
Narayana Turali
1

  1. Aditya Institute of Technology and Management, Tekkali 532201, Andhrapradesh, India
  2. Indian Institute of Technology, Roorkee 247667, Uttarakhand, India
  3. Jawaharlal Nehru Technological University, Kakinada 533003, Andhrapradesh, India

Abstrakt

The shift towards environmentally sustainable refrigerants is driven by the need to mitigate the impact of traditional refrigerants like R134a, which have high global warming potential. This study experimentally explores the performance of alternative refrigerants, R1234yf and R600a, when combined with compressor oils enhanced by Al₂O₃ and ZnO nanoparticles. A novel approach of using a hybrid nanofluid, incorporating both Al₂O₃ and ZnO nanoparticles, is proposed to optimise the performance of vapour compression refrigeration systems. The research involved preparing and characterising nano-additive compressor oils and evaluating their effects on key thermodynamic parameters across R1234yf and R600a refrigerants. The main objective of this study is to experimentally evaluate the impact of Al₂O₃ and ZnO nano-enhanced oils on refrigeration system perfor-mance, focusing on net refrigeration effect, compressor work, mass flow rate, theoretical compressor power, and coefficient of performance. The results indicate significant improvements in the coefficient of performance, mass flow rate, and net re-frigeration effect with the inclusion of nanoparticles in the refrigeration lubrication system. Particularly, the coefficient of performance increased from 2.71 to 3.34 for R134a, from 2.46 to 3.26 for R1234yf, and from 2.62 to 3.12 for R600a with the optimal nanoparticle combination (0.15g Al₂O₃ + 0.05g ZnO). Similarly, compressor power and work of compression were notably reduced, demonstrating enhanced energy efficiency. The optimal mixture (COA0.15Z0.05) shows the highest coeffi-cient of performance and reduced work of compression across all refrigerants. The study highlights that the hybrid nanoparticle approach not only boosts the performance of these refrigerants but also contributes to lower energy consumption and improved cooling efficiency.
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Autorzy i Afiliacje

Md. Gouse
1
B. Omprakash
1

  1. Department of Mechanical Engineering, Jawaharlal Nehru Technological University, College of Engineering, Anantapur 515002, Andhra Pradesh, India

Abstrakt

The article presents a method for online monitoring of thermal stress and heat transfer coefficient on the inner surface of a thick-walled cylindrical element using two separate applications. Both applications are based on the inverse heat conduction problem and use the control volume method. The first one allows the determination of thermal stresses based on measuring the wall temperature at a single point near the inner surface. This software is suitable for one-dimensional heat transfer, i.e. in a radial direction. The second application allows the heat transfer coefficient on the inner surface to be determined based on temperature measurements at six spatially distributed points. Knowledge of the heat transfer coefficient on the inner sur-face allows the stress concentration factor to be determined for elements weakened by an opening. This can be used to deter-mine the optimum heating or cooling rates for pressure elements or to determine the thermal stresses in elements weakened by an opening. This method is suitable for heat transfer cases in the radial, longitudinal and circumferential directions. The correct operation of both original applications has been tested on a laboratory stand, where there was a sudden change in the working fluid temperature in a steam header from 16.8°C to 142.5°C. At the beginning of the temperature change, the thermal stresses on the header inner surface reached a maximum value of -195.8 MPa, and the heat transfer coefficient was approxi-mately 5000 W/(m²K). Then, the thermal stresses began to decrease, and the heat transfer coefficient began to increase.
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Autorzy i Afiliacje

Jan Taler
1
Dawid Taler
1
Magdalena Jaremkiewicz
1
Karol Kaczmarski
1
Tomasz Sobota
1
Krzysztof Smaza
2

  1. Cracow University of Technology, Faculty of Environmental and Energy Engineering, ul. Warszawska 24, Cracow 31-155, Poland
  2. Evolution Group Krzysztof Smaza, ul. Sodowa 19/1, Cracow 30-376, Poland

Abstrakt

Although there is a great supply of groundwater, it is salty, and most places of the globe, including the Algerian desert, have a shortage of fresh water. The greatest answer to this issue is solar distillation since it uses sustainable solar energy. Solar still comes in a variety of forms, dimensions and styles, creating potable water that is fresh, clean, and safe to drink, albeit the amount of water produced differs depending on the type of solar still. Choosing the design of solar stills remains one of the preferred solutions to improve their performance. The performance of three different solar still designs is compared in this work, including single slope, hemispherical, and conical solar stills. The investigation used brackish water with a salt level of 3000 ppm and was conducted under the same operational conditions and locations. The conical solar still had the best overall performance, with a daily average production of 5.80 l/m2/day. The hemispherical solar still had the second-best performance, with a daily average production of 5.10 l/m2/day. Finally, the single slope solar still had the lowest performance (daily average production of 3.30 l/m2/day). The findings can be used to develop and improve solar stills for saltwater desalination.
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Autorzy i Afiliacje

Wael M. El-Maghlany
1
Mohammed El Hadi Attia
2
Abd Elnaby Kabeel
3 4
M.A. Elazab
5
Ammar Hidouri
6
Nour A. Moharram
7

  1. Mechanical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria 21544, Egypt
  2. Department of Physics, Faculty of Exact Science, University of El Oued, El Oued 39000, Algeria
  3. Mechanical Power Engineering Department, Faculty of Engineering, Tanta University, Tanta 31527, Egypt
  4. Faculty of Engineering, Delta University for Science and Technology, Gamasa 35712, Egypt
  5. Faculty of Engineering, Mechanical Power Engineering Department, Horus University-Egypt, New Damietta 34517, Egypt
  6. Research Lab of Technology, Energy and Innovative Materials, University of Gafsa, Gafsa 2112,Tunisia
  7. Mechanical Engineering Department, College of Engineering and Technology, Arab Academy for Science, Technologyand Maritime Transport, Alexandria 1029, Egypt

Abstrakt

This study experimentally investigates the performance of a fixed concentrated photovoltaics system consisting of a photo-voltaics module coupled with V-trough concentrators under partial shading conditions. V-troughs had the same trough angles, but different truncation levels (reflector lengths). Their geometric concentration ratios were 2.35 and 1.80. Research covers a wide range of operating parameters  generated power, electrical efficiency, module’s average temperature, and character-istic curves  offering a unique multidimensional experimental comparison of concentrated photovoltaics performance with V-troughs of different truncation. The objective is to determine a relationship between the V-trough geometry, working con-ditions, and generated power. Findings reveal that the maximum power point and short-circuit current are strong functions of the truncation level and angle of incidence. For angles close to 0°, these parameters reach greater values at lower truncation. At higher angles, this trend reverses. While concentrator-integrated systems have a higher peak power than the bare module (by 23% and 18% for the longer and shorter concentrators, respectively), they experience greater temporal fluctuations in operational parameters due to shading. Their daily average power production was comparable to that of the bare module as shading cast by V-trough reflectors led to a loss in the instantaneous generated power of up to 45% compared to the system with no concentrator. Thus, among the tested concentrators, the shorter one is more cost-effective due to reduced material consumption. Additionally, the maximum power of concentrator-integrated systems was produced when the module temper-ature reached 70ºC, rather than when the solar irradiance was maximum.
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Autorzy i Afiliacje

Stanislawa Halon
1
Natalia Stabrowska
1
Pawel Pacyga
1

  1. Wroclaw University of Science and Technology, Faculty of Mechanical and Power Engineering, Wyb. Wyspianskiego 27, Wroclaw, 50-370, Poland

Abstrakt

Ice damage is receiving increasing attention in engineering. In practice, the occurrence time of ice damage to small-diameter pile structures in cold regions is different from traditional knowledge. Given the crucial impact of temperature on ice thermal expansion, simulating the temperature field of ice cover is of great significance. Based on actual engineering simulations of ice cover temperature, the propagation and amplitude attenuation characteristics of temperature waves are analysed. The one-dimensional heat conduction equation is discretized using the Crank-Nicolson method (time step Δt = 60 s, spatial step Δz = 0.01 m) and implemented in MATLAB R2023a. According to the temperatures in Daqing, three typical warming pro-cesses are selected for fitting, and two ice cover thicknesses are combined to simulate six working conditions. The results show that the temperature field inside the ice cover changes under different working conditions, and the thickness of the ice cover and the temperature rise time have a significant impact. During cooling, the temperature inside the ice cover still rises, affecting thermal expansion stress. The results can provide an important basis for the prevention and control of ice damage to small diameter piles.
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Autorzy i Afiliacje

Jincheng Su
1 2 3
Jiliang Wang
2
Wei Zhou
3

  1. School of Energy and Civil Engineering, Harbin University of Commerce, Harbin 150028, China
  2. Heilongjiang Province Academy of Cold Area Building Research, Harbin 150080, China
  3. School of Civil Engineering, Harbin Institute of Technology, Harbin 150096, China

Abstrakt

The growing environmental challenges and the rapid depletion of global fossil fuel reserves have driven the urgent need to explore alternative energy sources. In present work, an experimental investigation evaluated the stability of ethanol-diesel blends using jatropha methyl ester (JME) as a co-solvent, alongside engine performance and emissions at varying injection pressures and timings. Stability tests revealed that ethanol cannot blend with diesel without additives, requiring at least 4% JME for one-day stability, with E10B10D80 (10% ethanol, 10% JME, and 80% diesel by volume) blends remaining stable above 10°C. Optimal injection parameters were identified as 2.0 × 10⁷ Pa pressure and 17° before top dead centre (BTDC) under different loads. JME proved effective as an additive, though its cost was higher than diesel, suggesting its long-term viability as fossil fuel resources diminish. Fuel consumption increased due to ethanol's lower calorific value, while thermal efficiency improved at low loads but decreased near full load. Emission analysis indicated that carbon monoxide (CO) emissions were lower at loads above half but higher at lower loads compared to pure diesel. Hydrocarbon (HC) emissions consistently rose with the blend, while a reduction in the nitrogen oxides (NOx) emissions was observed at relatively lower load but increased near full load, showing no consistent trend. The study highlights the potential of JME as a biofuel addi-tive, with its economic feasibility expected to improve as reliance on fossil fuels declines.
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Autorzy i Afiliacje

Arun Kumar
1
Surendra Kumar
2
Vipin Kumar Verma
3
Sandeep Singh
4
Rahul Shukla
5
Appurva Jain
6
Ankur Singh Bist
7
Pradeep Vishnoi
8
Vineet Kumar
9
Prabhakar Bhandari
6

  1. M.L.V. Textile and Engineering College, Bhilwara, 311001, Rajasthan, India
  2. Department of Business Management, H.N.B. Garhwal Central University, Srinagar Garhwal, 249161, Uttarakhand, India
  3. Department of Mathematics, SRM Institute of Science and Technology, Delhi-NCR Campus, Modinagar, Ghaziabad, 201204, Uttar Pradesh,India
  4. O.P. Jindal Global University, Sonipat, 131001, Haryana, India
  5. Mechanical Engineering Department, IET Bundelkhand University, Jhansi, 284001, Uttar Pradesh, India
  6. Mechanical Engineering Department, School of Engineering and Technology, K.R. Mangalam University, Gurugram, 122103, Haryana, India
  7. Department of Computer Science and Engineering, Graphic Era Hill University, Bhimtal Campus, 263136, Uttarakhand, India
  8. Department of Mechanical Engineering, BSM College of Engineering, Roorkee, 247666, Uttarakhand, India
  9. Department of Mechanical Engineering, Graphic Era Deemed to be University, Dehradun, 248002, Uttarakhand,India

Abstrakt

The growing environmental concerns and fossil fuel depletion have spurred interest in alternative fuels, with waste plastic oils emerging as a solution. Waste plastic oils not only help to reduce plastic waste but also contribute to energy production. This study investigates the effects of incorporating TiO2 nanoparticles into waste plastic pyrolysis oil (WPPO) and diethyl ether (DEE) blended with diesel fuel on engine working characteristics. The experimental analysis evaluated four fuel blends: pure diesel, WPD20 (20% WPPO in diesel), WPD20E5 (WPD20 with 5% DEE), WPD20E5T50 (WPD20E5 with 50 ppm TiO2 nanoparticles), and WPD20E5T100 (WPD20E5 with 100 ppm TiO2 nanoparticles) under various load conditions. The results demonstrated that the WPD20E5T100 blend achieved the highest brake thermal efficiency and the lowest brake specific fuel consumption, with improvements of up to 5.26% and 8.31%, respectively, in comparison to neat diesel. The blend also exhib-ited the most significant reductions in CO and unburnt hydrocarbon emissions, with reductions of up to 6.86% and 11.9%, respectively. Smoke emissions were notably lower with the TiO2 nanoparticle-enhanced blends, achieving an 11.8% improve-ment over diesel. Although NOx emissions were slightly higher with DEE, the WPD20E5T100 blend showed the maximum reduction in NOx emissions, with a reduction of 5.7% at full load. Overall, the WPD20E5T100 blend produced the optimum results at all loads.
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Autorzy i Afiliacje

Kavitha Banoth
1
Mohan Banoth
2
Srinivasnaik Mukuloth
3

  1. Research Scholar in the Department of Mechanical Engineering, Chaitanya deemed to be University, Hyderabad, India
  2. Department of Mechanical Engineering, Chaitanya deemed to be University, Hyderabad, India
  3. School of Engineering Jawaharlal Nehru University, JNU New Delhi, India

Instrukcja dla autorów

Submission of manuscript
Manuscripts should be electronically submitted to the Editorial System http://www.editorialsystem.com/aot. Each manuscript should be accompanied by a cover letter explaining why the manuscript is considered suitable for publication in the journal. The letter should contain:

• full title of the paper,
• full list of authors with affiliations,
• e-mail address of the authors,
• 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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