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Témakiírás |
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A kutatási téma leírása:
a.) Antecedents:
A steam power generation, called a Rankine cycle (RC) using water as a medium, is a promising technology applied to convert the amount of heat into electricity. Nevertheless, it seems that it has a limitation to recover the low-temperature heat, even the extreme one (i.e. in cryogenic temperature). For this reason, the RC using an organic working fluid (so-called organic Rankine cycle or ORC) is an appropriate solution to be implemented for various heat sources. In the simple layout, there are four main components: an evaporator, an expander/turbine coupled with a generator, a condenser and a pump. In the system, a turbine or expander is an essential machine to expand the working fluid so it can drive the shaft and generator to produce electricity.
Turbines have likely high performances operating at high rotational speeds, and it seems that gear-boxes are required to match the speed. In the low power ranges, the gear-box may cause a significant percentage reduction in the power output, and they are relatively expensive and heavy. For low-grade energy of ORC, the operating system may be varying temperature and fluctuating the operating condition. The operating condition may occur in the two-phase condition that in this stage, the droplet appears, and the turbine may not handle this phase (i.e. at a certain level, droplets will cause damage or erosion in turbines). The efficiency of the expansion process is the main concern in the ORC system. It looks that volumetric expanders are a good option for the system with this condition, low pressure and low temperature. They are mainly exploited in a micro and low-power ORC system and there are many types of volumetric expanders (e.g. piston, screw, scroll, vane, etc); however, only a few of them, like screw expanders may work under two-phase condition. It seems that screw expanders are promising technology applied for two-phase ORC; nevertheless, they are not suitable for low-grade ORC because of their rotational speed and productivity. In this case, investigation and analysis of volumetric expanders in the two-phase condition are necessary for fulfilling this new task.
b.) Aim of research:
The study aims to make volumetric expanders an attractive prime mover in a low-grade ORC system. The study will focus on the theoretical aspect, the modelling, and experiment of volumetric expansion in two-phase condition.
c.) Tasks, main items, necessary time:
Literature studies in the field of ORC system focusing on the application of volumetric expanders, heat transfer, applied low-boiling fluid, the technique of numerical and mathematical modelling of the thermal-flow process in ORC, participating in seminars, publication of the finding in the literature studies/review in journals (1 year).
Reviewing mathematical models in volumetric expanders used in ORC system, make modelling system, building test-stand experiment, participating in seminars, the publication of the research in journals (1 year).
Conducting experimental test on a test stand and developing research result, comparing the experiment and modelling system, participating in seminars, the publication of the research in journals (1 year).
Publication of the new scientific results (continuously), preparing the final documentation of results, writing the PhD dissertation (1 year).
d.) Required equipment:
Computer and numerical environment for modelling and simulation (e.g. MATLAB, ANSYS or OpenFOAM), modelling process software (e.g. DWSIM for open-source or ASPEN), the library of thermal properties (like CoolProp for open-source, NIST Webbook Chemistry, or RefProp), access to the scientific literature are readily available at either the Polish or the Hungarian department.
e.) Expected scientific results:
The above mentioned simulations are subjects of the publication since very few data are available in this research topic (i.e. two-phase expanders). The study will reveal which performance of two-phase ORC, the features, the characteristics and the boundary condition of the two-phase expansion. Also, the research will show the limitations of the two-phase condition for the volumetric expander.
f.) References:
- Ahmed, A. M., Kondor, L., & Imre, A. R. (2021). Thermodynamic Efficiency Maximum of Simple Organic Rankine Cycles. Energies, 14(2), 307.
- Badr, O., O'Callaghan, P. W., Hussein, M., & Probert, S. D. (1984). Multi-vane expanders as prime movers for low-grade energy organic Rankine-cycle engines. Applied Energy, 16(2), 129-146.
- Györke, G., Deiters, U. K., Groniewsky, A., Lassu, I., & Imre, A. R. (2018). Novel classification of pure working fluids for Organic Rankine Cycle. Energy, 145, 288-300.
- Imre, A. R., Kustán, R., & Groniewsky, A. (2020). Mapping of the Temperature–Entropy Diagrams of van der Waals Fluids. Energies, 13(6), 1519.
- Imre, A. R., Kustán, R., & Groniewsky, A. (2019). Thermodynamic selection of the optimal working fluid for organic Rankine cycles. Energies, 12(10), 2028.
- Kolasiński, P. (2020). The Method of the Working Fluid Selection for Organic Rankine Cycle (ORC) Systems Employing Volumetric Expanders. Energies, 13(3), 573.
- Kolasiński, P. (2019). Application of the Multi-Vane Expanders in ORC Systems—A Re-view on the Experimental and Modeling Research Activities. Energies, 12(15), 2975.
- Rak, J., Błasiak, P., & Kolasiński, P. (2018). Influence of the applied working fluid and the arrangement of the steering edges on multi-vane expander performance in micro ORC system. Energies, 11(4), 892.
- Kolasiński, P., Błasiak, P., & Rak, J. (2017). Experimental investigation on multi-vane expander operating conditions in domestic CHP ORC system. Energy Procedia, 129, 323-330.
- Kolasiński, P., Błasiak, P., & Rak, J. (2016). Experimental and numerical analyses on the rotary vane expander operating conditions in a micro organic Rankine cycle system. Energies, 9(8), 606.
- Kolasiński, P. (2015). The influence of the heat source temperature on the multivane ex-pander output power in an organic Rankine cycle (ORC) system. Energies, 8(5), 3351-3369.
- Gnutek, Z., & Kolasiński, P. (2013). The application of rotary vane expanders in organic rankine cycle systems—thermodynamic description and experimental results. Journal of engineering for gas turbines and power, 135(6).
előírt nyelvtudás: ENGLISH felvehető hallgatók száma: 1
Jelentkezési határidő: 2021-10-02 |
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