### Abstract

Language | English |
---|---|

Pages | 329-337 |

Number of pages | 9 |

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

Volume | 224 |

Issue number | 3 |

Early online date | 15 Dec 2009 |

DOIs | |

Publication status | Published - May 2010 |

Externally published | Yes |

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**Optimization of thermoacoustic stacks for low onset temperature engines.** / Yu, Z.; Jaworski, A.J.

Research output: Contribution to journal › Article

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 -