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1

Exploration of a model thermoacoustic turbogenerator with a bidirectional turbine

Korobko Volodymyr, Serbin Serhiy, Le Huu Cuong

Polish Maritime Research

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2023

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nr 4

102--109

EN

The utilisation of the thermal emissions of modern ship power plants requires the development and implementation of essentially new methods of using low-temperature waste heat. Thermoacoustic technologies are able to effectively use lowtemperature and cryogenic heat resources with a potential difference of 500–111 K. Thermoacoustic heat machines (TAHMs) are characterised by high reliability, simplicity and environmental safety. The wide implementation of thermoacoustic energy-saving systems is hampered by the low specific power and the difficulties of directly producing mechanical work. An efficient approach to converting acoustic energy into mechanical work entails the utilisation of axial pulse bidirectional turbines within thermoacoustic heat engines. These thermoacoustic turbogenerators represent comprehensive systems that consist of thermoacoustic primary movers with an electric generator actuated by an axial-pulse bidirectional turbine. The development of such a thermoacoustic turbogenerator requires several fundamental issues to be solved. For this purpose, a suitable experimental setup and a 3D computational fluid dynamics (CFD) model of a thermoacoustic engine (TAE) with bidirectional turbines were created. The research program involved conducting physical experiments and the CFD modelling of processes in a TAE resonator with an installed bidirectional turbine. The boundary and initial conditions for CFD calculations were based on empirical data. The adequacy of the developed numerical model was substantiated by the results of physical experiments. The CFD results showed that the most significant energy losses in bidirectional turbines are manifested in the output grid of the turbine.

2

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%.

3

Thermodynamic analysis of a thermoacoustic travelling wave engine

Ruziewicz A., Kruse A., Gnutek Z.

Journal of Mechanical and Energy Engineering

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2018

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Vol. 2, No 1

67--74

EN

Thermoacoustics has become a promising technology to use heat from low temperature sources to drive engines. This study proposes a single-stage thermoacoustic travelling-wave engine for waste-heat recovery at 150°C. All the construction details of such a system are provided. A recently developed configuration of a looped tube with an impedance matching side-branch stub is proposed. A numerical model of the engine is built in DeltaEC software to conduct the simulations. Furthermore, a detailed thermodynamic analysis of the engine is presented, including an energy balance, a description of the basic acoustic parameters in a steady state, as well as a study of a variable load influence on the performance of the engine. The Authors pointed out the necessity of the engine optimization and a proper choice of load related acoustic impedance, which would consider a trade-off between high power and high efficiency. Eventually, a possibility of achieving 40% exergy efficiency of the proposed engine is confirmed.

4

Badania silnika termoakustycznego na stanowisku dydaktycznym

Chmielewski A., Radkowski S.

Zeszyty Naukowe Instytutu Pojazdów / Politechnika Warszawska

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2014

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z. 3/99

5--12

PL

W pierwszej części pracy przedstawiono i sklasyfikowano urządzenia termoakustyczne. Podzielono je na urządzenia działające o falę biegnącą oraz te, które działają w oparciu o pobudzenie fali stojącej. Podzielono także urządzenia termoakustyczne na maszyny, które działają dzięki wytworzonemu gradientowi temperatury (silniki termoakustyczne) wytwarzają pracę mechaniczną, która zamieniana jest na energię elektryczną oraz urządzenia, które w wyniku pobudzonej fali akustycznej wytwarzają ciepło bądź chłód (pompy ciepła, chłodziarki). W drugiej części pracy przedstawiono stanowisko dydaktyczne, na którym przeprowadzono wstępne badania. Zaprezentowano wyniki wpływu umiejscowienia źródła ciepła na pobudzenie fali akustycznej oraz wpływu temperatury grzałki na prędkość obrotową silnika termoakustycznego.

EN

The first part of this article presents classification of thermoacoustic devices. These devices were divided on machines which running on the wave running and also machines based on the standing wave excitation. Moreover in the article divided thermoacoustic devices on machines which work has been made using a temperature gradient (thermoacoustic engines), those devices produce mechanical work, which is converted to electricity and another devices, as a result of stimulated acoustic waves produce heat or cold (heat pumps, refrigerators). In the second part of the paper presents the didactic test bench at which was conducted primary research. The results of the location of the heat source for the excitation of acoustic waves and the effect of temperature of the heater thermoacoustic engine speed was presented.

5

Application of CFD technique for modelling of the thermoacoustic engine

Rulik S., Remiorz L., Dykas S.

Archives of Thermodynamics

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2011

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Vol. 32, no. 3

175-190

EN

The paper is concerned with an important issue from the field of thermoacoustics - the numerical modelling of the flow field in the thermoacoustic engine. The presented way of modelling is based on the solution to fundamental fluid mechanics equations that govern the flow of compressible, viscous, and heat-transferring gas. The paper presents the way of modelling the thermoacoustic engine, the way of conducting calculations and the results which illustrate the correctness of the selected computational technique.

6

Numerical Modelling of Thermoacoustic Phenomenon as Contribution to Thermoacoustic Engine Model

Remiorz L., Dykas S., Rulik S.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2010

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Vol. 14, No 3

257-269

EN

The presented paper shows our first step into the numerical modelling of the thermoacoustic phenomenon. The thermoacoustic effect has a great application potential, for instance, in thermoacoustic engines or thermoacoustic mixture separation. These two applications are in the centre of our interest. The modelling of thermoacoustic effects consists in a solution of transport equations, mass, momentum and energy, to identify the influence of heat transfer on the sonic oscillation and vice versa. The numerical modelling of such sensitive and sophisticated phenomena requires a high quality numerical tool. The commercial CFD code ANSYS CFX 12 was chosen as the numerical tool. This investigation will be supported by using the finite time thermodynamic theory. At the beginning preliminary numerical tests were performed in order to validate the numerical methods and the boundary conditions implemented in CFX. The numerical calculations of the Rijke tube were carried out and the results were validated against analytical relations.