Applied sciences

Archives of Thermodynamics

Content

Archives of Thermodynamics | 2020 | vol. 41 | No 4

Download PDF Download RIS Download Bibtex

Abstract

The aim of this paper is twofold: to estimate the unsteady pressure-flow variations in gas transmission pipelines using the ensemblebased data assimilation approach and to analyse the strength of steel tubes reinforced with composite sleeves containing localized part-wall thickness loss caused by corrosion while taking into consideration a safe operating pressure of the pipeline. For a steel thin-walled cylinder containing a partwall metal loss, a flexible wrap of fibreglass as well as carbon glass with epoxy resin are determined. The strength of the repaired pipeline with two kinds of materials for sleeves is investigated taking into consideration the internal pressure at the defect location. For the case study, a section of the Yamal transit pipeline on the Polish territory is selected. The results enable pipeline operators to evaluate the strength of corroded steel pipelines and develop optimal repair activities, which are of vital importance for the maintenance and operation of underground steel networks.

Go to article

Authors and Affiliations

Maciej Witek
Ferdinand Uilhoorn
Download PDF Download RIS Download Bibtex

Abstract

Identification of working fluids and development of their mathematical models should always precede construction of a proper model of the analysed thermodynamic system. This paper presents method of development of a mathematical model of working fluids in a gas turbine system and its implementation in Python programming environment. Among the thermodynamic parameters of the quantitative analysis of systems, the following were selected: specific volume, specific isobaric and isochoric heat capacity and their ratio, specific enthalpy and specific entropy. The development of the model began with implementation of dependencies describing the semi-ideal gas. The model was then extended to the real gas model using correction factors reflecting the impact of pressure. The real gas equations of state were chosen, namely due to Redlich–Kwong, Peng–Robinson, Soave– Redlich–Kwong, and Lee–Kesler. All the correction functions were derived analytically from the mentioned equations of real gas behaviour. The philosophy of construction of computational algorithms was presented and relevant calculation and numerical algorithms were discussed. Created software allowed to obtain results which were analysed and partially validated.

Go to article

Authors and Affiliations

Paweł Trawiński
Download PDF Download RIS Download Bibtex

Abstract

Recently, significant progress has been made in experimental studies on the flow of wet steam, measuring techniques based on recording the phenomenon of extinction of light and ultrasound have been elaborated or improved. The basic value experimentally determined in the final stage was the content of the liquid phase defined as the wetness fraction. The methodology of tests and experimental investigations was presented, as well as the applied and developed measurement systems. Next, some developed designs of new ultrasonic and light extinction measuring probe and their modifications are described. The article presents also some examples of applications of the developed measurement techniques in application to experimental research conducted on wet steam. Examples of comparison between experimental and numerical tests for the extinction method are also provided.

Go to article

Authors and Affiliations

Mirosław Majkut
Sławomir Dykas
Krystian Smołka
Download PDF Download RIS Download Bibtex

Abstract

Power boilers should be characterized by high flexibility in terms of loads, which results from the demand for electricity. In addition to the flexibility of the boiler, it is also important for the boiler to operate under technical minimum conditions while maintaining harmful emissions standards. A boiler operating with a technical minimum should also exhibit a stable combustion process. The paper presents the results of numerical combustion research for the minimum load of the two-pass ultrasupercritical boiler with front wall swirl burners system. The combustion stability for the minimum boiler load of 40% for the three mill system configurations has been demonstrated. Based on the numerical tests carried out in terms of obtaining the most favourable combustion conditions and the emission of harmful substances, the most favourable of them cases was indicated.

Go to article

Authors and Affiliations

Bartłomiej Hernik
Wiesław Zabłocki
Download PDF Download RIS Download Bibtex

Abstract

This paper presents a comparison of three surface condenser connection setups on the cooling water side. Four connections were considered, namely serial, mixed and two parallel ones. The analysis was conducted based on the calculated heat balances of proposed power unit for nominal and not nominal parameters for tested connections. Thermodynamic justification for the use of more complex configuration was verified. The exhaust steam pressure calculation was presented. Three methods of computing the heat transfer coefficient based on characteristic numbers, namely the Heat Exchange Institute (HEI) method, and the American Society of Mechanical Engineers (ASME) standard, were used. Calculation results were validated with the real data. The most accurate model was indicated and used in heat balance calculations. The assumptions and simplifications for the calculations are discussed. Examples of the calculation results are presented.

Go to article

Authors and Affiliations

Ewa Dobkiewicz-Wieczorek
Download PDF Download RIS Download Bibtex

Abstract

Maritime transport is facing a set of technical challenges due to implementation of ecological criterions on 1st Jan. 2020 and 2021 by the International Maritime Organization. The advantageous properties of natural gas (NG) as fuel in conjunction with dual-fuel (DF) internal combustion engines (ICE) potentially enables the fulfilment of all criterions. Moreover the 2020 global sulfur cap in combination with its low content in NG potentially enables to recover higher rates of waste heat and exergy of exhaust gas without the risk of low temperature corrosion. In this study the influence of sulfur content in NG and pilot fuel oil (PFO) on the sulfuric acid condensation temperature was investigated in order to determine the rate of waste heat (quantity) and exergy (quality) of four-stroke DF IC engine’s exhaust for 50%, 85% and 100% of engine load. Determined parameters were compared with two sets of reference values calculated for the same engine: a) fueled with NG and PFO with fixed minimum exhaust temperature set as 423.15 K, b) fueled with 3.5% sulfur mass fraction fuel oil only with variable minimum exhaust gas temperature. The results show that the assumption of case a) can lead to significant reduction of recovered rates of exhaust waste heat and exergy in the ranges of 10% to 24% and 43% to 57%, respectively. Higher values were obtained for case b) where the ranges of unrecovered rate of heat and exergy achieved 20% to 38% and 60% to 70%.

Go to article

Authors and Affiliations

Mateusz Przybyła
Andrzej Adamkiewicz
Download PDF Download RIS Download Bibtex

Abstract

Thermodynamics deals with irreversible transformations of substances. Every thermodynamic property of a substance, as a function of two parameters describing its state, can be illustrated as a simply connected manifold. The term manifold stands for the Methods of Geometrical Representation of Thermodynamic Properties of Substances by Means of Surfaces. Generally, every transformation of a substance changes its energy (or enthalpy) by heat transfer and work done on it. All such changes (transformations) are considered to be irreversible and can be described using appropriate manifolds. Studies show that every transformation is associated with the degradation of energy. Such relations (between heat, work and other forms of energy or enthalpy) can be described by the Pfaff formulas and their integrations.

This article discusses the issue of irreversible energy degradation in heat transfer between two fluids. Irreversible heat transfer between separated fluids most often occurs through surface heat exchangers. All such processes are determined by convective heat transfer in thermal boundary layers and conduction through the wall. Consequently, entropy changes of fluids in heat and mass transfer can be observed in these layers. While the entropy rate of the heating fluid is negative and that of the heated medium is positive, the sum of entropy changes of all substances involved in the heat transfer process is always positive. These sums, known as entropy increase (entropy generation), can be interpreted as the measure of irreversible degradation of energy in heat transfer processes. The consequence of this degradation is that an arbitrary engine powered by the degraded (lower-temperature) heat flux will operate at a lower efficiency. The significance of this discussion relates especially to cases in power plants and cooling systems where surface heat exchangers are used. In the discussion proposed is the entropy increase as a criterion of irreversible energy degradation in heat transfer. Such introduced measure of effectiveness leads to an analysis of local overall heat transfer coefficient optimization on the cone-shaped manifold.

Go to article

Authors and Affiliations

Zbigniew Drożyński
Download PDF Download RIS Download Bibtex

Abstract

One of the problems in Russia Power Sector strategy until 2035 is the technologies development for mitigation of harmful emissions by the heat and power production industry. This goal may be reached by the transition to environmentally friendly generation units such as oxy-fuel combustion power cycles that burn organic fuels in pure oxygen. This paper provides the results of research on one of the most efficient oxy-fuel combustion power cycle, which was modified by the usage of nitrogen for turbine cooling. The computer simulation and parametric optimization approaches are described in detail. The net efficiency of the oxy-fuel combustion power cycle in relationship to the carbon dioxide turbine exhaust pressure is shown. Moreover, the influence of the regenerator scheme and modeling parameters on heat performance is obtained. Particularly, it was found that the transition to a scheme with five two-threaded heat exchangers decrease cycle efficiency by 4.2% compare to a scheme with a multi-stream regenerator.

Go to article

Authors and Affiliations

Vladimir Kindra
Andrey Rogalev
Olga Vladimirovna Zlyvko
Alexey Zonov
Matvey Smirnov
Ilya Kaplanovich
Download PDF Download RIS Download Bibtex

Abstract

The purpose of this work is to design and determine the performance of a prototype centrifugal pump impeller for an organic Rankine cycle (ORC) power plant of maximum power 100 kW. The centrifugal pump is especially designed to work on the same shaft as the corresponding ORC microturbine. The ORC unit works on R7100 (HFE7100) – a lowboiling fluid characterized by a zero ozone depletion potential coefficient. The pump has the following rated parameters: nominal flow rate of working fluid 4 kg/s, operating rotor speed 10 000 rpm. The pump designed by means of the 0D meanline method is subject to computational fluid dynamics (CFD) calculations and analysis. The obtained flow field results are discussed and performance characteristics of the pump are presented. The non-cavitating operational region is determined for the pump.

Go to article

Authors and Affiliations

Piotr Klimaszewski
Piotr Klonowicz
Piotr Lampart
Łukasz Witanowski
Dawid Zaniewski
Łukasz Jędrzejewski
Tomasz Suchocki
Download PDF Download RIS Download Bibtex

Abstract

The paper presents studies of mathematical modelling in transonic flow through the first stage rotor of the axial compressor of homogenous and heterogeneous condensation. The condensation phenomena implemented into a commercial software is based on the classical theory of nucleation and molecular-kinetic droplet growth model. Model is validated against experimental studies available in the literature regarding the flow through the first stage of turbine compressor, i.e. the rotor37 transonic compressor benchmark test. The impact of air humidity and air contamination on the condensation process for different flow conditions is examined. The influence of latent heat release due to condensation exerts a significant impact on the flow structure, thus the analysis of the air humidity and contamination influence on the condensation is presented. The results presented indicate the non-negligible influence of air humidity on the flow structure in the transonic flow regime, thus it is recommended to take condensation phenomenon under consideration in high-velocity airflow simulations.

Go to article

Authors and Affiliations

Piotr Paweł Wiśniewski
Sławomir Dykas
Guojie Zhang
Download PDF Download RIS Download Bibtex

Abstract

The energy industry is undergoing a major upheaval. In Germany, for example, the large nuclear and coal-fired power plants in the gigawatt scale are planned to be shut down in the forthcoming years. Electricity is to be generated in many small units in a decentralized, renewable and environmentally friendly manner. The large 1000 MW multistage axial steam turbines used to this date are no longer suitable for these tasks. For this reason, the authors examine turbine architectures that are known per se but have fallen into oblivion due to their inferior efficiency and upcoming electric drives about 100 year ago. However, these uncommon turbine concepts could be suitable for small to micro scale distributed power plants using thermodynamic cycles, which use for example geothermal wells or waste heat from industry to generate electricity close to the consumers. Thus, the paper describes and discusses the concept of a velocity-compounded single wheel re-entry cantilever turbine in comparison with other turbine concepts, especially other velocity-compounded turbines like the Curtis-type. Furthermore, the authors describe the design considerations, which led to a specific design of a 5 kW air turbine demonstrator, which was later manufactured and investigated. Finally, first numerical as well as experimental results are presented, compared and critically discussed with regards to the originally defined design approach.

Go to article

Authors and Affiliations

Andreas Paul Weiss
Philipp Streit
Tobias Popp
Patrick Shoemaker
Thomas Hildebrandt
Václav Novotný
Jan Špale
Download PDF Download RIS Download Bibtex

Abstract

An important operational task for thermal turbines during run-up and run-down is to keep the stresses in the structural elements at a right level. This applies not only to their instantaneous values, but also to the impact of them on the engine lifetime. The turbine shaft is a particularly important element. The distribution of stresses depends on geometric characteristics of the shaft and its specific locations. This means a groove manufactured for fixing the rotor blades. The extreme stresses in this place occur during the start-up and the shaft heating to normal operating temperature. The process needs optimisation. Optimization tasks are multidisciplinary issues and can be carried out using different methods. In recent years, particular attention in optimisation has been paid to the use of artificial intelligence methods. Among them, a special role is assigned to genetic algorithms. The paper presents a genetic algorithm method to optimise the steam turbine shaft heating process during its start-up phase. The presented optimization task of this algorithm is to carry out the process of the shaft heating as soon as possible at the conditions of not exceeding the stresses at critical locations at any heating phase.

Go to article

Authors and Affiliations

Krzysztof Dominiczak
Marta Drosińska-Komor
Romuald Rzadkowski
Jerzy Głuch
Download PDF Download RIS Download Bibtex

Abstract

The airflow through a two-dimensional horizontal rectangular cross-section channel in the presence of two baffles has been numerically examined and analyzed in the steady turbulent regime. The baffles were of the zig-zag type or plane one. The calculations are based on the finite volume approach and the average Navier–Stokes equations along with the energy equation, have been solved using the SIMPLE algorithm. The nonuniform structured quadrilateral-type element mesh is used in this study. The fluid flow patterns represented for Reynolds numbers based on the hydraulic diameter of the channel ranging from 5000 to 20 000. Effects of various Reynolds number values on flow fields, dimensionless axial velocity profiles, as well as local and average friction coefficients in the test channel is presented. The obtained results show that the flow structure is characterized by strong deformations and large recirculation regions. In general, the fluid velocity and skin friction loss rise with the increase in the flow rate and hence the Reynolds number.

Go to article

Authors and Affiliations

Chafika Zidani
Boumédiènne Benyoucef
Faouzi Didi
Nabila Guendouz

Instructions for authors

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 paper should not exceed the length of 25 pages. All pages should be numbered. The plan and form of the papers should be as follows:

1. 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 of maximum 15 typewritten lines and Keywords.

2. More important symbols used in the paper can 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).

3. All abbreviations should be spelled out first time they are introduced in the text.

4. 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 page.

5. 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.

6. 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.

7. 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.

8. Computer files on an enclosed disc or sent by e-mail to the Editorial Office are welcome. The manuscript should be written as a MS Word file – ∗.doc, ∗.docx or LATEX file – ∗.tex. For revised manuscripts after peer review process, figures should 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. Figures created in MS World, Exel, or PowerPoint will not be accepted. The quality of images downloaded from websites and the Internet are also not acceptable, because of their low resolution (usually only 72 dpi), inadequate for print reproduction.

9. 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:

(a) for books: the publishing house and the place and year of publication, for example:
[1] Holman J.P.: Heat Transfer. McGraw-Hill, New York 1968.

(b) for journals: the name of the journal, volume (Arabic numerals in bold), year of publication (in round brackets), number and, if appropriate, numbers of relevant pages, for example:
[2] Rizzo F.I., Shippy D.I.: A method of solution for certain problems of transient heat conduction . AIAA J. 8(1970), No. 11, 2004–2009.

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.

10. 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.


Manuscript submission

Manuscripts to be considered for publication should be electronically submitted to the Editorial Office via the online submission and reviewing system, the Editorial System, at http://www.editorialsystem.com/aot. Submission to the journal proceeds totally on line and you will be guided stepwise throughout the process of the creation and uploading of your files. The body of the text, tables and figures, along with captions for figures and tables should be submitted separately. The system automatically converts source files to a single PDF file article, for subsequent approval by the corresponding Author, which is then used in the peer-review process. All correspondence, including notification confirming the submission of the manuscripts to the Editorial Office, notification of the Editorsñs decision and requests for revision, takes place by e-mails. Authors should designate the corresponding author, whose responsibility is to represent the Authors in contacts with the Editorial Office. Authors are requested not to submit the manuscripts by post or e-mail.
The illustrations may be submitted in color, however they will be printed in black and white in the journal, so the grayscale contributions are preferable. Therefore, the figure caption and the entire text of the paper should not make any reference to color in the illustration. Moreover the illustration should effectively convey author’s intended meaning when it is printed as a halftone. The illustrations will be reproduced in color in the online publication.


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

Submission of the manuscript means that the authors automatically agree to assign the copyright to the Publisher. Once a paper has been accepted for publication, as a condition of publication, the authors are asked to send by email a scanned copy of the signed original of the Transfer of Copyright Agreement, signed by the Corresponding Author on behalf of all authors to the Managing Editor of the Journal. The copyright form can be downloaded from the journal’s website at http://www.imp.gda.pl/archives-of-thermodynamics/ under Notes for Contributors.

This page uses 'cookies'. Learn more