所謂的熱聲效應裝置, 主要可分為將熱能轉化為聲波之原動機型, 以及利用聲波將熱排走之熱泵型兩種型態
, 而本實驗中之將嘗試製造一具約6公分大小之熱泵型熱聲裝置, 試著朝將熱聲裝置微性化之目標發展
。 本實驗裝置使用壓克力材質之密閉腔, 使聲波在密閉腔內形成駐波, 密閉腔長度為半波長, 當所操作的聲波振盪頻率越高, 密閉腔長度則越短
, 而聲波源則使用可產生最大1434 Pa(peak to peak)聲波壓力之壓電致動器, 聲波振盪頻率操作為2800 Hz
, 本論文中實驗條件包括使用不同間隙 、 長度及材質之薄片板堆, 觀察薄片堆兩端溫差隨壓力振幅改變之變化
, 實驗結果發現當聲波壓力振幅越大時, 薄片堆兩端溫差越大
, 本實驗中產生最佳的溫差為羊毛纖維薄片堆所產生的, 在壓電致動器所能產生之最大壓力 1434 Pa(peak to peak)之情況下
, 長度1 cm羊毛纖維薄片堆兩端可產生之溫差為3.4C, 而長度1 cm麥拉聚酯薄片堆兩端可產生之溫差則為2.3C。

Thermoacoustic device is a proven technology in the industry. However, thermoacoustic devices suffer from their low efficiency and did not receive serious attention of researchers in the past. Furthermore, the performance of small sized thermoacoustic devices has not been properly assessed.

In the present study, a miniaturized (centimeter-sized) thermoacoustic heat pump using high heat capacity and low heat conductivity materials such as mylar and wool as stack materials and driven by a PZT bimorph is constructed. An acoustic standing wave is maintained in the half-wavelength air-tight tube by the PZT bimorph. The maximum acoustic pressure of 1434Pa (peak to peak) is achieved at the natural frequency (2800Hz) of the PZT bimorph actuator. The critical bottleneck in the construction of centimeter-sized thermoacoustic heat pump lies in the fabrication of stack plates with tiny spacing of several hundred microns. Stacks with spacings of 200 and 350 10^-6m and various lengths were built successfully.

In our experiment, we found the temperature difference at the two extremities increases with the increasing acoustic pressure amplitude. The largest temperature difference achieved is 3.4 degree C for a 1 cm long wool stack and 2.3 degree C for a 1 cm long mylar stack. A preliminary evaluation of the performance of the constructed device is also discussed.

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