Applied sciences

Archives of Thermodynamics

Content

Archives of Thermodynamics | 2010 | No 2 July |

Download PDF Download RIS Download Bibtex

Abstract

Cooling of the hot gas path components plays a key role in modern gas turbines. It allows, due to efficiency reasons, to operate the machines with temperature exceeding components' melting point. The cooling system however brings about some disadvantages as well. If so, we need to enforce the positive effects of cooling and diminish the drawbacks, which influence the reliability of components and the whole machine. To solve such a task we have to perform an optimization which makes it possible to reach the desired goal. The task is approached in the 3D configuration. The search process is performed by means of the evolutionary approach with floatingpoint representation of design variables. Each cooling structure candidate is evaluated on the basis of thermo-mechanical FEM computations done with Ansys via automatically generated script file. These computations are parallelized. The results are compared with the reference case which is the C3X airfoil and they show a potential stored in the cooling system. Appropriate passage distribution makes it possible to improve the operation condition for highly loaded components. Application of evolutionary approach, although most suitable for such problems, is time consuming, so more advanced approach (Conjugate Heat Transfer) requires huge computational power. The analysis is based on original procedure which involves optimization of size and location of internal cooling passages of cylindrical shape within the airfoil. All the channels can freely move within the airfoil cross section and also their number can change. Such a procedure is original.

Go to article

Authors and Affiliations

Grzegorz Nowak
Download PDF Download RIS Download Bibtex

Abstract

In the 21st century the way to increase the efficiency of new sources of energy is directly related with extended exploration of renewable energy. This modern tendency ensures the fuel economy needs to be realized with nature protection. The increasing of new power sources efficiency (cogeneration, trigeneration systems, fuel cells, photovoltaic systems) can be performed by application of solid sorption heat pumps, regrigerators, heat and cold accumulators, heat transformers, natural gas and hydrogen storage systems and efficient heat exchangers.

Go to article

Authors and Affiliations

L. Vasiliev
O. Filatova
A. Tsitovich
Download PDF Download RIS Download Bibtex

Abstract

The paper presents a one-dimensional mathematical model for simulating the transient processes which occur in the liquid flat-plate solar collector tubes. The proposed method considers the model of collector tube as one with distributed parameters. In the suggested method one tube of the collector is taken into consideration. In this model the boundary conditions can be time-dependent. The proposed model is based on solving the equation describing the energy conservation on the fluid side. The temperature of the collector tube wall is determined from the equation of transient heat conduction. The derived differential equations are solved using the implicit finite difference method of iterative character. All thermo-physical properties of the operating fluid and the material of the tube wall can be computed in real time. The time-spatial heat transfer coefficient at the working fluid side can be also computed on-line. The proposed model is suitable for collectors working in a parallel or serpentine tube arrangement. As an illustration of accuracy and effectiveness of the suggested method the computational verification was carried out. It consists in comparing the results found using the presented method with results of available analytic solutions for transient operating conditions. Two numerical analyses were performed: for the tube with temperature step function of the fluid at the inlet and for the tube with heat flux step function on the outer surface. In both cases the conformity of results was very good. It should be noted, that in real conditions such rapid changes of the fluid temperature and the heat flux of solar radiation, as it was assumed in the presented computational verification, do not occur. The paper presents the first part of the study, which aim is to develop a mathematical model for simulating the transient processes which occur in liquid flat-plate solar collectors. The experimental verification of the method is a second part of the study and is not presented in this paper. In order to perform this verification, the mathematical model would be completed with additional energy conservation equations. The experimental verification will be carry out in the close future.

Go to article

Authors and Affiliations

Wiesław Zima
Piotr Dziewa
Download PDF Download RIS Download Bibtex

Abstract

The paper investigates the possibility of utilisation of heat-recirculating systems for fuel conversions having low net thermal effect. The experimental part is conducted with an electrically heated heat exchanger. It is shown that heat-recirculating systems can operate under superadiabatic conditions. Their thermal characteristics are provided by means of the dependencies of heat recirculation ratio on process parameters. Further, the heat-recirculating catalytic combustion system is characterised via combustion bifurcation diagrams. The similarities and differences of both those heat-recirculating systems are qualitatively compared and explained. Bifurcation characteristics proves to be useful tools in concise description of practical complex heat-recirculating fuel conversion systems in energy generation.

Go to article

Authors and Affiliations

Wojciech Budzianowski
Download PDF Download RIS Download Bibtex

Abstract

This work presents an application possibility of sorption refrigerators driven by low temperature fluid for air conditioning of buildings. Thermodynamic models were formulated and absorption LiBr-water chiller with 10 kW cooling power as well as adsorption chiller with silica gel bed were investigated. Both of them are using water for desorption process with temperature Tdes = 80 °C. Coefficient of performance (COP) for both cooling cycles was analyzed in the same conditions of the driving heat source, cooling water Tc = 25 °C and temperature in evaporator Tevap = 5 °C. In this study, the computer software EES was used to investigate the performance of absorption heat pump system and its behaviour in configuration with geothermal heat source.

Go to article

Authors and Affiliations

Agnieszka Kuczyńska
Władysław Szaflik

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