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Influence of Working Conditions on Parameters of Thermoacoustic Engine with Travelling Wave

Dobrucki Andrzej, Kruk Bartłomiej

Archives of Acoustics

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2020

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Vol. 45, No. 3

467--473

EN

Thermoacoustic converters are devices for direct conversion of acoustic energy into thermal energy in the form of temperature difference, or vice versa – for converting thermal energy into an acoustic wave. In the first case, the device is called a thermoacoustic heat pump, in the second – thermoacoustic engine. Thermoacoustic devices can use (or produce) a standing or travelling acoustic wave. This paper describes the construction and properties of a single-stage thermoacoustic engine with a travelling wave. This kind of engine works using the Stirling cycle. It uses gas as a working medium and does not contain any moving parts. The main component of the engine is a regenerator equipped with two heat exchangers. Most commonly, a porous material or a set of metal grids is used as a regenerator. An acoustic wave is created as a result of the temperature difference between a cold and a hot heat exchanger. The influence of working gas, and such parameters as static pressure and temperature at heat exchanger on the thermoacoustic properties of the engine, primarily its efficiency, was investigated. The achieved efficiency was up to 1.4% for air as the working medium, which coincides with the values obtained in other laboratories. The efficiency for argon as working gas is equal to 0.9%.

2

Vibrations of plate strips with internal periodic structure

Marczak J., Jędrysiak J.

Engineering Transactions

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2015

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Vol. 63, iss. 1

93--108

EN

In this note vibrations of thin periodic plate strips with periodically distributed systems of three concentrated masses are analysed. Results of the non-asymptotic tolerance model are compared to those by the exact discrete model. In an example, these models are used to calculate lower and higher frequencies of the travelling wave related to the internal periodic structure.

3

Travelling Wave Single End Fault Location Method based on Network Information

Chen Y., Liu D., Xu B.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 11a

205-209

EN

The single end travelling wave fault location method is usually difficult to discriminate the reflection wave of fault point. This paper employs wavelet transform to detect possible fault point in power system. Using the real time network topology and possible fault point, the travelling wave propagation waveform can be constructed. By comparing the constructed waveforms and real recorded waveform, the reflection wave of fault point can be identified. The simulation verifies its correctness, and the field application proves the feasibility of this method.

PL

W artykule zaprezentowano metodę lokalizacji możliwych awarii w sieci energetycznej na podstawie Transformaty Falkowej. Wyniki badań symulacyjnych i eksperymentalnych potwierdzają skuteczność metody.

4

Some remarks on dynamic results for averaged and exact models of thin periodic plates

Jędrysiak J., Michalak B.

Journal of Theoretical and Applied Mechanics

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2005

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Vol. 43 nr 2

405--425

EN

The aim of the paper is to show certain justification of the new non-asymptotic model of thin periodic plates, derived using the tolerance averaging (Wo?niak and Wierzbicki, 2000). The model describes the effect of periodicity cell size on overall plate behaviour, on the contrary to known homogenised models. Results obtained from those models will be compared to solution to and from the "exact" discrete model. It is shown that for long-wave propagation problems, results obtained for a special case of a periodic plate strip (weightless but covered by a periodically distributed system of two concentrated masses) within the non-asymptotic model are close results calculated from the known "exact" solutions based on the method used to analyse longitudinal vibrations of one-dimensional diatomic lattice (Brillouin, 1953). Similar conformity, taking place in special cases of short waves, is also presented.

PL

Celem pracy jest dokonanie pewnej weryfikacji nowego nieasymptotycznego modelu cienkich płyt periodycznych, wyprowadzonego przy zastosowaniu tolerancyjnego uśredniania (Woźniak i Wierzbicki, 2000). W przeciwieństwie do znanych modeli zhomogenizowanych, model ten opisuje wpływ wymiaru komórki periodyczności na ogólną pracę płyty. Wyniki uzyskane w ramach tych modeli będą porównane z rozwiązaniem według "dokładnego" modelu dyskretnego. Można pokazać, że w zagadnieniach propagacji fal długich wyniki otrzymane w ramach modelu nieasymptotycznego dla szczególnego przypadku periodycznego pasma płytowego (nieważkiego lecz z periodycznie rozłożonym układem dwóch mas skupionych) są bliskie wynikom uzyskanym ze znanych rozwiązań "dokładnych", które wykorzystują metodę stosowaną do analizy drgań podłużnych jednowymiarowej dwuatomowej siatki (Brillouin, 1953). Pokazano także podobną zgodność wyników w szczególnych przypadkach propagacji fal krótkich.