Nauki Techniczne

Archives of Thermodynamics

Zawartość

Archives of Thermodynamics | 2013 | No 4 December

Abstrakt

Heat exchangers of different types find application in power systems based on solid oxide fuel cells (SOFC). Compact plate fin heat exchangers are typically found to perfectly fit systems with power output under 5 kWel. Micro-combined heat and power (micro-CHP) units with solid oxide fuel cells can exhibit high electrical and overall efficiencies, exceeding 85%, respectively. These values can be achieved only when high thermal integration of a system is assured. Selection and sizing of heat exchangers play a crucial role and should be done with caution. Moreover, performance of heat exchangers under variable operating conditions can strongly influence efficiency of the complete system. For that reason, it becomes important to develop high fidelity mathematical models allowing evaluation of heat exchangers under modified operating conditions, in high temperature regimes. Prediction of pressure and temperatures drops at the exit of cold and hot sides are important for system-level studies. Paper presents dedicated mathematical model used for evaluation of a plate fin heat exchanger, operating as a part of micro-CHP unit with solid oxide fuel cells.

Przejdź do artykułu

Autorzy i Afiliacje

Jakub Kupecki
Krzysztof Badyda

Abstrakt

Controlling low-temperature drying facilities which utilise nonprepared air is quite difficult, due to very large variability of ventilation air parameters - both in daily and seasonal cycles. The paper defines the concept of cumulative drying potential of ventilation air and presents experimental evidence that there is a relation between this parameter and condition of the dried matter (sewage sludge). Knowledge on current dry mass content in the dried matter (sewage sludge) provides new possibilities for controlling such systems. Experimental data analysed in the paper was collected in early 2012 during operation of a test solar drying facility in a sewage treatment plant in Błonie near Warsaw, Poland.

Przejdź do artykułu

Autorzy i Afiliacje

Piotr Krawczyk

Abstrakt

The trigeneration systems for production of cold use sorption refrigeration machines: absorption and adsorption types. Absorption systems are characterized namely by better cooling coefficient of performance, while the adsorptive systems are characterized by the ability to operate at lower temperatures. The driving heat source temperature can be as low as 60-70 °C. Such temperature of the driving heat source allows to use them in district heating systems. The article focuses on the presentation of the research results on the adsorption devices designed to work in trigeneration systems.

Przejdź do artykułu

Autorzy i Afiliacje

Andrzej Grzebielec
Artur Rusowicz

Abstrakt

The objective of the paper is to analyse thermodynamical and operational parameters of the supercritical power plant with reference conditions as well as following the introduction of the hybrid system incorporating ORC. In ORC the upper heat source is a stream of hot water from the system of heat recovery having temperature of 90 °C, which is additionally aided by heat from the bleeds of the steam turbine. Thermodynamical analysis of the supercritical plant with and without incorporation of ORC was accomplished using computational flow mechanics numerical codes. Investigated were six working fluids such as propane, isobutane, pentane, ethanol, R236ea and R245fa. In the course of calculations determined were primarily the increase of the unit power and efficiency for the reference case and that with the ORC.

Przejdź do artykułu

Autorzy i Afiliacje

Dariusz Mikielewicz
Jarosław Mikielewicz
Paweł Ziółkowski

Abstrakt

A mathematical model of the steam superheater exchanger with distributed parameters has been developed. Scale deposits were assumed to be present on the internal tube surfaces. It was assumed that the inner tube surfaces are covered by a thin layer of scale deposits. The finite volume method was used to solve partial differential equations describing flue gas, tube wall and steam temperature. The developed modeling technique can especially be used for modeling tube heat exchangers when detail information on the tube wall temperature distribution is needed. The numerical model of the superheater developed in the paper can be used for modeling of the superheaters with complex flow arrangement accounting scales on the internal tube surfaces. Using the model proposed the detailed steam, wall and flue gas temperature distribution over the entire superheater can be determined. The steam pressure distribution along its path flow and the total heat transfer rate can also be obtained. The calculations showed that the presence of scale on the internal surfaces of the tubes cause the steam temperature decrease and the heat flow rate transferred from the flue gas to the steam. Scale deposits on the inner surfaces of the tubes cause the tube wall temperature growth and can lead to premature wear of tubes due to overheating.

Przejdź do artykułu

Autorzy i Afiliacje

Marcin Trojan
Jan Taler

Abstrakt

A gas turbine air bottoming cycle consists of a gas turbine unit and the air turbine part. The air part includes a compressor, air expander and air heat exchanger. The air heat exchanger couples the gas turbine to the air cycle. Due to the low specific heat of air and of the gas turbine exhaust gases, the air heat exchanger features a considerable size. The bigger the air heat exchanger, the higher its effectiveness, which results in the improvement of the efficiency of the gas turbine air bottoming cycle. On the other hand, a device with large dimensions weighs more, which may limit its use in specific locations, such as oil platforms. The thermodynamic calculations of the air heat exchanger and a preliminary selection of the device are presented. The installation used in the calculation process is a plate heat exchanger, which is characterized by a smaller size and lower values of the pressure drop compared to the shell and tube heat exchanger. Structurally, this type of the heat exchanger is quite similar to the gas turbine regenerator. The method on which the calculation procedure may be based for real installations is also presented, which have to satisfy the economic criteria of financial profitability and cost-effectiveness apart from the thermodynamic criteria.

Przejdź do artykułu

Autorzy i Afiliacje

Tadeusz Chmielniak
Sebastian Lepszy
Daniel Czaja

Abstrakt

Paper deals with theoretical analysis of possible efficiency increase of compression refrigeration cycles by means of application of a twophase ejector. Application of the two phase ejector in subcritical refrigeration system as a booster compressor is discussed in the paper. Results of exergy analysis of the system operating with various working fluids for various operating conditions have been shown. Analysis showed possible exergy efficiency increase of refrigeration compression cycle.

Przejdź do artykułu

Autorzy i Afiliacje

Jarosław Karwacki
Adam Dudar
Dariusz Butrymowicz
Kamil Śmierciew

Abstrakt

The paper deals with the computational fluid dynamics modelling of carbon dioxide capture from flue gases in the post combustioncapture method, one of the available carbon capture and storage technologies. 30% aqueous monoethanolamine solution was used as a solvent in absorption process. The complex flow system including multiphase countercurrent streams with chemical reaction and heat transfer was considered to resolve the CO2 absorption. The simulation results have shown the realistic behaviour and good consistency with experimental data. The model was employed to analyse the influence of liquid to gas ratio on CO2 capture efficiency.

Przejdź do artykułu

Autorzy i Afiliacje

Paweł Niegodajew
Dariusz Dariusz Asendrych
Stanisław Drobniak

Abstrakt

In the paper the results of analysis of an integrated gasification combined cycle IGCC polygeneration system, of which the task is to produce both electricity and synthesis gas, are shown. Assuming the structure of the system and the power rating of a combined cycle, the consumption of the synthesis gas for chemical production makes it necessary to supplement the lack of synthesis gas used for electricity production with the natural gas. As a result a change of the composition of the fuel gas supplied to the gas turbine occurs. In the paper the influence of the change of gas composition on the gas turbine characteristics is shown. In the calculations of the gas turbine the own computational algorithm was used. During the study the influence of the change of composition of gaseous fuel on the characteristic quantities was examined. The calculations were realized for different cases of cooling of the gas turbine expander’s blades (constant cooling air mass flow, constant cooling air index, constant temperature of blade material). Subsequently, the influence of the degree of integration of the gas turbine with the air separation unit on the main characteristics was analyzed.

Przejdź do artykułu

Autorzy i Afiliacje

Łukasz Bartela
Janusz Kotowicz

Abstrakt

The analyzed heat accumulator is a key element in a hybrid heating system. In this paper, analytical and numerical models of the ceramic heat accumulator are presented.The accuracy of finite difference methods will be assessed by comparing the results with those obtained from the exact analytical solution.

Przejdź do artykułu

Autorzy i Afiliacje

Dawid Taler
Piotr Cisek

Abstrakt

The paper presents a thermodynamic optimization of 900MW power unit for ultra-supercritical parameters, modified according to AD700 concept. The aim of the study was to verify two optimisation methods, i.e., the finding the minimum of a constrained nonlinear multivariable function (fmincon) and the Nelder-Mead method with their own constrain functions. The analysis was carried out using IPSEpro software combined with MATLAB, where gross power generation efficiency was chosen as the objective function. In comparison with the Nelder-Mead method it was shown that using fmincon function gives reasonable results and a significant reduction of computational time. Unfortunately, with the increased number of decision parameters, the benefit measured by the increase in efficiency is becoming smaller. An important drawback of fmincon method is also a lack of repeatability by using different starting points. The obtained results led to the conclusion, that the Nelder-Mead method is a better tool for optimisation of thermal cycles with a high degree of complexity like the coal-fired power unit.

Przejdź do artykułu

Autorzy i Afiliacje

Łukasz Kowalczyk
Witold Elsner

Abstrakt

The influences of various operating conditions including cathode inlet air flow rate, electrolyte temperature and fuel particles size on the performance of the direct carbon fuel cell DCFC were presented and discussed in this paper. The experimental results indicated that the cell performance was enhanced with increases of the cathode inlet gas flow rate and cell temperature. Binary alkali hydroxide mixture (NaOH-LiOH, 90-10 mol%) was used as electrolyte and the biochar of apple tree origin carbonized at 873 K was used as fuel. Low melting temperature of the electrolyte and its good ionic conductivity enabled to operate the DCFC at medium temperatures of 723-773 K. The highest current density (601 A m−2) was obtained for temperature 773 K and air flow rate 8.3×106 m3s−1. Itwas shown that too low or too high air flow rates negatively affect the cell performance. The results also indicated that the operation of the DCFC could be improved by proper selection of the fuel particle size.

Przejdź do artykułu

Autorzy i Afiliacje

Andrzej Kacprzak
Rafał Kobyłecki
Zbigniew Bis

Abstrakt

This paper presents the parameters of the reference oxy combustion block operating with supercritical steam parameters, equipped with an air separation unit and a carbon dioxide capture and compression installation. The possibility to recover the heat in the analyzed power plant is discussed. The decision variables and the thermodynamic functions for the optimization algorithm were identified. The principles of operation of genetic algorithm and methodology of conducted calculations are presented. The sensitivity analysis was performed for the best solutions to determine the effects of the selected variables on the power and efficiency of the unit. Optimization of the heat recovery from the air separation unit, flue gas condition and CO2 capture and compression installation using genetic algorithm was designed to replace the low-pressure section of the regenerative water heaters of steam cycle in analyzed unit. The result was to increase the power and efficiency of the entire power plant.

Przejdź do artykułu

Autorzy i Afiliacje

Mateusz Brzęczek
Łukasz Bartela

Abstrakt

This paper presents a gas turbine combined cycle plant with oxy-combustion and carbon dioxide capture. A gas turbine part of the unit with the operating parameters is presented. The methodology and results of optimization by the means of a genetic algorithm for the steam parts in three variants of the plant are shown. The variants of the plant differ by the heat recovery steam generator (HRSG) construction: the singlepressure HRSG (1P), the double-pressure HRSG with reheating (2PR), and the triple-pressure HRSG with reheating (3PR). For obtained results in all variants an economic evaluation was performed. The break-even prices of electricity were determined and the sensitivity analysis to the most significant economic factors were performed.

Przejdź do artykułu

Autorzy i Afiliacje

Janusz Kotowicz
Marcin Job

Abstrakt

In generalized method of data reconciliation as equations of conditions beside substance and energy balances can be used equations which don’t have precisely the status of conservation lows. Empirical coefficients in these equations are traded as unknowns’ values. To this kind of equations, in application of the generalized method of data reconciliation in supercritical power unit, can be classified: steam flow capacity of a turbine for a group of stages, adiabatic internal efficiency of group of stages, equations for pressure drop in pipelines and equations for heat transfer in regeneration heat exchangers. Mathematical model of a power unit was developed in the code Thermoflex. Using this model the off-design calculation has been made in several points of loads for the power unit. Using these calculations identification of unknown values and empirical coefficients for generalized method of data reconciliation used in power unit has been made. Additional equations of conditions will be used in the generalized method of data reconciliation which will be used in optimization of measurement placement in redundant measurement system in power unit for new control systems

Przejdź do artykułu

Autorzy i Afiliacje

Marcin Szega
Grzegorz Tadeusz Nowak

Abstrakt

The paper presents the results of investigations on a cyclone with additional gas extraction. The experiments were performed in the cyclone with a diameter of 0.2 m equipped with a truncated counter-cone situated in the dust bin inlet. The gas stream flowing through the countercone was 10 and 20% of the gas supplied to the cyclone. The separation efficiencies and pressure loss were measured. The experiment showed that the extraction of gas by the counter-cone deteriorated the cyclone efficiency and forcing the outflow of gas through the counter-cone requires the use of an additional outlet fan.

Przejdź do artykułu

Autorzy i Afiliacje

Arkadiusz Kępa

Abstrakt

Passive autocatalytic recombiners (PAR) is the only used method for hydrogen removal from the containment buildings in modern nuclear reactors. Numerical models of such devices, based on the CFD approach, are the subject of this paper. The models may be coupled with two types of computer codes: the lumped parameter codes, and the computational fluid dynamics codes. This work deals with 2D numerical model of PAR and its validation. Gaseous hydrogen may be generated in water nuclear reactor systems in a course of a severe accident with core overheating. Therefore, a risk of its uncontrolled combustion appears which may be destructive to the containment structure.

Przejdź do artykułu

Autorzy i Afiliacje

Magdalena Orszulik
Adam Fic
Tomasz Bury
Jan Składzień

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

Ta strona wykorzystuje pliki 'cookies'. Więcej informacji