Numerical study of oscillatory flow and heat transfer in a loaded thermoacoustic stack

Journal Article · Fri Jan 01 04:00:00 EST 1999 · Numerical Heat Transfer. Part A, Applications

DOI:https://doi.org/10.1080/104077899275362· OSTI ID:328381

Worlikar, A S; Knio, O M ^[1]

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1. Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Mechanical Engineering

A thermoacoustic refrigerator may be idealized as consisting of a straight resonance tube housing a stack of parallel plates and heat exchangers, and an acoustic source. Among the advantages of thermoacoustic refrigerators are the simplicity of their design and the fact that they naturally avoid the need for harmful refrigerants such as chlorofluorocarbons (CFCs). The operation of these devices is based on exploiting the well-known thermoacoustic effect to induce a temperature difference across the stack and to transport heat from one end of the plate to the other. Heat exchangers are then used to transfer energy from the thermoacoustic refrigerator to hot and cold reservoirs. A two-dimensional, low-Mach-number computational model is used to analyze the unsteady flow and temperature fields in the neighborhood of an idealized stack/heat exchanger configuration. The model relies on a vorticity-based formulation of the mass, momentum, and energy equations in the low-Mach-number, short-stack limit. The stack and heat exchangers are assumed to consist of flat plates of equal thickness. The heat exchanger plates are assumed isothermal and in perfect thermal contact with the stack plates. The simulations are used to study the effect of heat exchanger size and operating conditions on the heat transfer and stack performance. Computed results show that optimum stack performance is achieved when the length of the heat exchanger is nearly equal to the peak-to-peak particle displacement. Numerical estimates of the mean enthalpy flux within the channel are in good agreement with the predictions of linear theory. However, the results reveal that a portion of the heat exchangers is ineffective due to reverse heat transfer. Details of the energy flux density around the heat exchangers are visualized, and implications regarding heat exchanger design and model extension are discussed.

• Sponsoring Organization: Office of Naval Research, Washington, DC (United States)
• OSTI ID: 328381
• Journal Information: Numerical Heat Transfer. Part A, Applications, Journal Name: Numerical Heat Transfer. Part A, Applications Journal Issue: 1 Vol. 35; ISSN NHAAES; ISSN 1040-7782
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ACOUSTICS
DESIGN
HEAT EXCHANGERS
HEAT TRANSFER
MATHEMATICAL MODELS
NUMERICAL ANALYSIS
PERFORMANCE
REFRIGERATORS
UNSTEADY FLOW