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Simulating Rayleigh Streaming and Heat Transfer in a Standing-Wave Thermoacoustic Engine via a Thermal Lattice Boltzmann Method

Simulating Rayleigh Streaming and Heat Transfer in a Standing-Wave Thermoacoustic Engine via a... The streaming flow and convective heat transfer in a standing-wave thermoacoustic engine (SWTAE) filled with helium gas were numerically handled. The mathematical model depicting the flow and heat transfer occurring consists of the extended Brinkman–Forchheimer–Darcy equations under Boussinesq approximation and completed by the temperature equation based on local thermal equilibrium assumption. Their numerical resolution was performed using a thermal lattice Boltzmann method (TLBM) with the approximation of Bhatnagar–Gross–Krook (BGK) implemented in an in-house solver. Such an approach is further validated by a previous study available in the literature with good agreement. The phase variation of streaming velocity, the convective heat effect on Rayleigh streaming, and temperature gradient and porosity effects on SWTAE thermal efficiency have been investigated and amply commented on. It turned out that the convection effect on the acoustic velocity is mainly observed on the engine core hot side while it is negligible on the cold side. Likewise, its influence on the Rayleigh streaming is particularly detected at low thermal gradient and that the minimization of the Rayleigh effect improves the thermoacoustic conversion at large thermal gradient. On the other hand, such efficiency is improved with increasing the core porosity. Based on the findings obtained, the TLBM approach adopted seems suitable to predict such flow's behavior. Thereby, the present work opens up a new course to model and characterize the flow and transfer of heat by convection in a SWTAE. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png International Journal of Thermophysics Springer Journals

Simulating Rayleigh Streaming and Heat Transfer in a Standing-Wave Thermoacoustic Engine via a Thermal Lattice Boltzmann Method

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References (56)

Publisher
Springer Journals
Copyright
Copyright © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2022
ISSN
0195-928X
eISSN
1572-9567
DOI
10.1007/s10765-022-03016-x
Publisher site
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Abstract

The streaming flow and convective heat transfer in a standing-wave thermoacoustic engine (SWTAE) filled with helium gas were numerically handled. The mathematical model depicting the flow and heat transfer occurring consists of the extended Brinkman–Forchheimer–Darcy equations under Boussinesq approximation and completed by the temperature equation based on local thermal equilibrium assumption. Their numerical resolution was performed using a thermal lattice Boltzmann method (TLBM) with the approximation of Bhatnagar–Gross–Krook (BGK) implemented in an in-house solver. Such an approach is further validated by a previous study available in the literature with good agreement. The phase variation of streaming velocity, the convective heat effect on Rayleigh streaming, and temperature gradient and porosity effects on SWTAE thermal efficiency have been investigated and amply commented on. It turned out that the convection effect on the acoustic velocity is mainly observed on the engine core hot side while it is negligible on the cold side. Likewise, its influence on the Rayleigh streaming is particularly detected at low thermal gradient and that the minimization of the Rayleigh effect improves the thermoacoustic conversion at large thermal gradient. On the other hand, such efficiency is improved with increasing the core porosity. Based on the findings obtained, the TLBM approach adopted seems suitable to predict such flow's behavior. Thereby, the present work opens up a new course to model and characterize the flow and transfer of heat by convection in a SWTAE.

Journal

International Journal of Thermophysics – Springer Journals

Published: Jul 1, 2022

Keywords: Porous medium; Rayleigh streaming; Standing wave; Thermal-acoustic efficiency; Thermoacoustic engine; Thermal lattice Boltzmann method

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