Optimization of thermoacoustic stacks for low onset temperature engines

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Standing-wave thermoacoustic engines are typically optimized in order to obtain high system efficiency. However, in applications targeting the utilization of waste heat, it may be necessary to optimize them for a low onset temperature difference instead, so as to enable the engine's self-oscillation using low-grade energy sources. This article focuses on theoretical investigations of the critical temperature gradient in stacks, based on the assumptions of a short stack in a standing-wave acoustic field and an ideal gas. A dimensionless critical temperature gradient factor is obtained on the basis of the linear thermoacoustic theory and the analysis of the viscous and thermal relaxation losses for selected stack geometries. With a simple form, it reveals the effects of the stack geometry, the characteristic channel dimension, and the local acoustic impedance on the critical temperature gradient of the stack. In particular, it is shown that the impedance determines the proportion between the viscous loss, heat relaxation losses, and the power production from the heat energy. Numerical analysis based on this dimensionless factor clearly shows that there is an optimum channel dimension for each given stack location in the acoustic field. There exists a possible optimum combination of these parameters, which leads to the lowest critical temperature gradient.
LanguageEnglish
Pages329-337
Number of pages9
JournalProceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy
Volume224
Issue number3
Early online date15 Dec 2009
DOIs
Publication statusPublished - May 2010
Externally publishedYes

Fingerprint

Thermoacoustics
Thermal gradients
Engines
Acoustic fields
Thermoacoustic engines
Temperature
Acoustic impedance
Geometry
Waste heat
Heat losses
Numerical analysis
Gases
Hot Temperature

Cite this

@article{418970d04a244390beab5e5bf5459101,
title = "Optimization of thermoacoustic stacks for low onset temperature engines",
abstract = "Standing-wave thermoacoustic engines are typically optimized in order to obtain high system efficiency. However, in applications targeting the utilization of waste heat, it may be necessary to optimize them for a low onset temperature difference instead, so as to enable the engine's self-oscillation using low-grade energy sources. This article focuses on theoretical investigations of the critical temperature gradient in stacks, based on the assumptions of a short stack in a standing-wave acoustic field and an ideal gas. A dimensionless critical temperature gradient factor is obtained on the basis of the linear thermoacoustic theory and the analysis of the viscous and thermal relaxation losses for selected stack geometries. With a simple form, it reveals the effects of the stack geometry, the characteristic channel dimension, and the local acoustic impedance on the critical temperature gradient of the stack. In particular, it is shown that the impedance determines the proportion between the viscous loss, heat relaxation losses, and the power production from the heat energy. Numerical analysis based on this dimensionless factor clearly shows that there is an optimum channel dimension for each given stack location in the acoustic field. There exists a possible optimum combination of these parameters, which leads to the lowest critical temperature gradient.",
keywords = "Thermoacoustic stack, Critical temperature gradient, Geometrical configuration",
author = "Z. Yu and A.J. Jaworski",
year = "2010",
month = "5",
doi = "10.1243/09576509JPE845",
language = "English",
volume = "224",
pages = "329--337",
journal = "Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy",
issn = "0957-6509",
publisher = "SAGE Publications",
number = "3",

}

TY - JOUR

T1 - Optimization of thermoacoustic stacks for low onset temperature engines

AU - Yu, Z.

AU - Jaworski, A.J.

PY - 2010/5

Y1 - 2010/5

N2 - Standing-wave thermoacoustic engines are typically optimized in order to obtain high system efficiency. However, in applications targeting the utilization of waste heat, it may be necessary to optimize them for a low onset temperature difference instead, so as to enable the engine's self-oscillation using low-grade energy sources. This article focuses on theoretical investigations of the critical temperature gradient in stacks, based on the assumptions of a short stack in a standing-wave acoustic field and an ideal gas. A dimensionless critical temperature gradient factor is obtained on the basis of the linear thermoacoustic theory and the analysis of the viscous and thermal relaxation losses for selected stack geometries. With a simple form, it reveals the effects of the stack geometry, the characteristic channel dimension, and the local acoustic impedance on the critical temperature gradient of the stack. In particular, it is shown that the impedance determines the proportion between the viscous loss, heat relaxation losses, and the power production from the heat energy. Numerical analysis based on this dimensionless factor clearly shows that there is an optimum channel dimension for each given stack location in the acoustic field. There exists a possible optimum combination of these parameters, which leads to the lowest critical temperature gradient.

AB - Standing-wave thermoacoustic engines are typically optimized in order to obtain high system efficiency. However, in applications targeting the utilization of waste heat, it may be necessary to optimize them for a low onset temperature difference instead, so as to enable the engine's self-oscillation using low-grade energy sources. This article focuses on theoretical investigations of the critical temperature gradient in stacks, based on the assumptions of a short stack in a standing-wave acoustic field and an ideal gas. A dimensionless critical temperature gradient factor is obtained on the basis of the linear thermoacoustic theory and the analysis of the viscous and thermal relaxation losses for selected stack geometries. With a simple form, it reveals the effects of the stack geometry, the characteristic channel dimension, and the local acoustic impedance on the critical temperature gradient of the stack. In particular, it is shown that the impedance determines the proportion between the viscous loss, heat relaxation losses, and the power production from the heat energy. Numerical analysis based on this dimensionless factor clearly shows that there is an optimum channel dimension for each given stack location in the acoustic field. There exists a possible optimum combination of these parameters, which leads to the lowest critical temperature gradient.

KW - Thermoacoustic stack

KW - Critical temperature gradient

KW - Geometrical configuration

UR - http://journals.sagepub.com/home/pia

U2 - 10.1243/09576509JPE845

DO - 10.1243/09576509JPE845

M3 - Article

VL - 224

SP - 329

EP - 337

JO - Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy

T2 - Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy

JF - Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy

SN - 0957-6509

IS - 3

ER -