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Abstract

The paper presents the first off-grid system designed to supply electricity to the equipment mounted on components of the district heating network in district heating chambers. The proposed off-grid system is equipped, among other things, with a turbine and a generator intended for electricity production. On-grid power supply is a common way of providing electricity with strictly defined, known and verified operating parameters. For off-grid power supply, however, there are no documented testing results showing such parameters. This paper presents selected results of tests and measurements carried out during the operation of an off-grid supply system powering the equipment installed in a district heating chamber. The values of voltage obtained from a turbine-driven generator are analysed in detail. The analysis results can be used as the basis for further works aiming to optimize the off-grid system of electricity supply to devices installed in district heating chambers.
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Authors and Affiliations

Robert Wiśniewski
1
Agata Kania
1
Wiesław Zima
2
Jan Taler
2

  1. Municipal Heat Supply Company, Jana Pawła II 188, 30-969 Kraków, Poland
  2. Cracow University of Technology, Department of Energy, Jana Pawła II 37, 31-864 Kraków, Poland
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Abstract

Machines utilising renewable energy constantly undergo research aimed at raising their efficiency. One of them is a Savonius wind turbine, where scientists propose adjustments to improve its aerodynamic properties. At present, their assessment is usually performed by means of transient computational fluid dynamics simulations with two- or threedimensional models. In this paper, the overset (chimera) mesh approach was applied to investigate the performance of a Savonius wind turbine equipped with deformable blades. They were continuously deformed during rotation by a dedicated mechanism to increase a positive torque of the advancing blade, and meanwhile, decrease a negative torque of the returning blade. A quasi-two-dimensional model with a two-way fluid-structure interaction method was applied, where the structural solver determined blade deflection caused by the predefined deformation mechanism and aerodynamic loads, whereas the coupled computational fluid dynamics solver determined the transient flow. The deformable blades rotor performance was calculated and compared with a conventional rigid Savonius turbine, both simulated using the overset mesh approach. The average value of the power coefficient achieved a 55% rise in the case of deformable blades turbine. Additionally, to validate the overset method, its results were compared with the classical sliding mesh method for a conventional rigid rotor.
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Bibliography

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[2] Masdari M., Tahani M., Naderi M.H., Babayan N.: Optimization of airfoil Based Savonius wind turbine using coupled discrete vortex method and salp swarm algorithm. J. Clean. Prod. 222(2019), 47–56.
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[7] Sobczak K., Obidowski D., Reorowicz P., Marchewka E.: Numerical investigations of the savonius turbine with deformable blades. Energies 13(2020), 14, 3717.
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Authors and Affiliations

Emil Marchewka
1
Krzysztof Sobczak
1
Piotr Reorowicz
1
Damian Stanisław Obidowski
1
Krzysztof Jóźwik
1

  1. Lodz University of Technology, Institute of Turbomachinery, Wólczanska 219/223, 90-924 Łódz, Poland
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Abstract

The article consists of two parts. In the first one (introductory) I recall—following Edmund Husserl, Stanisław Ossowski and Adam Schaff—the main formulations of the “principle of transparency of the sign.” In these formulations it is usually said about (1) the transparency of the sign regarding objects denoted by the sign (denoted, designated and/or named), or (2) the transparency of the sign regarding its meaning (respectively, events, states of affairs and facts designated by the sign). However, as Husserl pointed out, one can also speak about (3) the transparency of the sign in relations to the activities and mental states of the sign’s users (senders and recipients). After all, only due to the transparency of the sign understood in this way, it is possible for people to communicate with each other, thus the sign can also has an expressive and communicative function. In turn, the second part of the article (essential) contains a reconstruction of the Leon Koj’s approach; Koj gave a consistently formalized form to the theory of sign based on the principle of transparency— the form of an axiomatized logical system (using Quine's formalism from his Mathematical Logic). One of Koj's main goals was also to indicate the close relationship between semantics and pragmatics, and even the primacy of pragmatics over semantics. Formal-logical tools have also shown that the theory of sign based on the principle of transparency neither contravene The Law of Non-Contradiction (at least in its psychological formulation), nor contain or imply semantic antinomies such us antinomy of the liar. Because it is a theory easily negotiable with Alfred Tarski’s theory of language levels.

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Authors and Affiliations

Józef Dębowski

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