Performance measurements on a thermoacoustic refrigerator driven at high amplitudes

Area of Science:

• Thermodynamics
• Acoustics
• Mechanical Engineering

Background:

• Thermoacoustic refrigerators offer high power density, driven by acoustic power.
• Increasing pressure amplitude is key to enhancing cooling power in thermoacoustic devices.
• Previous Space Thermo-Acoustic Refrigerator (STAR) designs operated at lower pressure ratios.

Purpose of the Study:

• To investigate the performance of a modified STAR operating at higher pressure amplitudes (up to 6%).
• To compare experimental results with predictions from the DELTAE linear acoustic computer model.
• To quantify deviations in heat pumping and acoustic power at moderate amplitudes.

Main Methods:

• Modification of the Space Thermo-Acoustic Refrigerator (STAR).
• Operation at peak-to-mean pressure ratios up to 6%.
• Comparison of experimental data with the DELTAE computer model.
• Precise measurement of exhaust heat using sensitive instrumentation (65 mW absolute accuracy).

Main Results:

• Achieved 30 W of cooling power, a five-fold increase compared to previous STAR reports.
• Observed a 23% deviation in heat pumping power between experimental data and the linear DELTAE model at 6% pressure ratio.
• Identified significant disagreement between measured and modeled acoustic power requirements.

Conclusions:

• Thermoacoustic refrigerators can achieve significantly higher cooling power at increased pressure amplitudes.
• Linear acoustic models show measurable deviations from experimental performance at moderate amplitudes.
• Further research is needed to refine models for accurate prediction of thermoacoustic device performance at higher operating pressures.