témavezető: Imre Attila
helyszín (magyar oldal): BME Department of Energy Engineering, Building D. 225/A helyszín rövidítés: EGR
A kutatási téma leírása:
a.) Antecedents:
During the last few decades, power generation from low-temperature heat sources (below 300 ℃) like thermal solar, geothermal, biomass or waste heat has been becoming more and more significant. Since traditional Rankine cycle using water as working fluid cannot be used with good efficiency at low temperatures, the need to find novel working fluids for Rankine cycles of for other, less frequently used thermodynamic cycles are urgent.
In the recent years, the trial-and-error method to find better working fluids has been replaced by more sophisticated theoretical studies, using physical and chemical methods to predict the properties of various fluids. One of the novel method proposed, that one of the major factor to qualify a fluid to be a potentially applicable working fluid is related to the active molecular degree of freedom of the given material, which can be quantified by the isochoric heat capacity. Additionally, traditional classification of pure, one-component working fluids proved to be insufficient for the proper description. The traditional classification is based on the quality of the expanded vapour after an isentropic (adiabatic and reversible) expansion from saturated vapour state, and distinguishes merely three categories: wet, dry and isentropic working fluids. Although the behaviour of fluids of the different classes differs characteristically, but these three classes are not enough to find the thermodynamically best working fluid for a given heat source. Therefore a novel classification was developed, using the characteristic points of the specific entropy – temperature (often referred as T-s) diagram of the substances. Parallel to these direct studies, the thermodynamic behind basic processes, used to describe thermodynamic cycles (like adiabatic compression and expansion, isobaric heat exchange, etc.) was studied to improve the description of the total thermodynamic cycles.
b.) Aim of research:
We are going to work on the improvement of the novel classification method to characterize working fluids, including the application of real fluids and mixtures as well as on the better thermodynamic description of the elementary processes of thermodynamic cycles. Extensibility of results for other cycles (like trans- and supercritical ORC and various flash-cycles) are going to be considered. One of the specialty of our research plan is the extension of the study of fluid properties and thermodynamic processes from normal fluid condition to supercritical ones and also to metastable ones. While the normal and supercritical conditions can be important during normal working conditions of a power plant, metastable ones (for example overheated liquids) are characteristic for accidental conditions, extending the project to the field of safety.
c.) Tasks, main items, necessary time:
- review of the literature (6 months)
- applicability of the novel classification to real material and defining quantitative limits between various working fluid classes (6 months)
- applicability of the novel classification to design thermodynamic cycle for a given heat source (6 months)
- extension of the description for other thermodynamic cycles, including transcritical Rankine cycle and various flash cycles (especially trilateral flash cycle) (6 months)
- study adiabatic processes under supercritical conditions (6 months)
- study various (isentropic to isentalpic) expansion starting from supercritical condition and going to metastable states (i.e. accidental pressure loss of supercritical systems) (6 months)
- study isochoric and isobaric processes in metastable (overheated) liquids (6 months)
- writing of the thesis (6 months)
Tasks can be completed parallel.
d.) Required equipment:
Computer, access to literature and databases, mathematical/simulation software
e.) Expected scientific results:
Developing novel methods to find working fluids for various heat sources. Better description of elementary processes used in thermodynamic cycles.
From these topics, we are planning to publish 3-5 papers with international journals with impact factors, as well as to contribute several posters and/or oral presentations on at least 2-3 different scientific conferences.
f.) References:
[1] A. Groniewsky, G. Györke, A. R. Imre: Description of wet-to-dry transition in model ORC working fluids, Applied Thermal Engineering, 125 (2017) 963–971.
[2] A. R. Imre, S. E. Quinones-Cisneros, U. K. Deiters: Adiabatic processes in the liquid–vapor two-phase region - 1. Pure fluids, Industrial&Engineering Chemistry Research, 53(2014) 13529-13542.
[3] Gábor Györke, Axel Groniewsky, Attila R. Imre: A simple method to find new dry and isentropic working fluids for Organic Rankine Cycle, Energies, 12 (2019) 480, doi: 10.3390/en12030480
[4] G. Györke, U. K. Deiters, A. Groniewsky, I. Lassu, A. R. Imre: Novel Classification of Pure Working Fluids for Organic Rankine Cycle, Energy, 145 (2018) 288-300.
[5] A. R. Imre, C. Ramboz, U.K. Deiters and T. Kraska: Anomalous fluid properties of carbon dioxide in the supercritical region – Application to geological CO2 storage and related hazards, Environmental Earth Sciences, 73 (2015) 4373–4384.
előírt nyelvtudás: english felvehető hallgatók száma: 1
Jelentkezési határidő: 2019-10-12
2024. IV. 17. ODT ülés Az ODT következő ülésére 2024. június 14-én, pénteken 10.00 órakor kerül sor a Semmelweis Egyetem Szenátusi termében (Bp. Üllői út 26. I. emelet).
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