Studi Eksperimen Tentang Pengaruh Lokasi Regenerator, Frekuensi Bunyi dan Daya Listrik Masukan Terhadap Unjuk Kerja Pendingin Termoakustik Gelombang Berjalan

ALI HAMIDI, Ikhsan Setiawan, S.Si., M.Si.; Prof. Dr. Agung B.S. Utomo, S.U.

2015 | Skripsi | S1 FISIKA

Telah dilakukan penelitian tentang pengaruh lokasi regenerator, frekuensi sumber bunyi dan daya masukan sumber bunyi terhadap unjuk kerja pendingin termoakustik gelombang berjalan. Pendingin termoakustik gelombang berjalan terdiri atas sebuah regenerator, sebuah simpal pipa (looped-tube) dan sebuah pelantang (loudspeaker). Regenerator dibuat dua buah dengan panjang 4 cm terbuat dari susunan rapat lembaran-lembaran kasa kawat baja antikarat masing-masing dengan ukuran kasa #40 dan #50. Simpal pipa terbuat dari pipa PVC (polyvinyl chloride) komersial berdiameter dalam 55,0 mm dan tebal 2,6 mm. Loudspeaker yang digunakan memiliki diameter 10 inchi dan impedansi 4 ohm dan dihubungkan dengan simpal pipa dengan menggunakan pipa PVC lurus sepanjang 15 cm. Regenerator diletakkan di dalam simpal pipa yang letaknya divariasi untuk mencari lokasi regenerator terbaik. Posisi regenerator 0,1 ternormalisasi menghasilkan penurunan suhu terbesar yaitu sebesar (3,6 plus minus 0,5) derajat Celsius. Pada rentang frekuensi yang lebar, yaitu 30 Hz - 400 Hz, teramati adanya pembalikan sisi panas dan sisi dingin pada regenerator ketika frekuensi divariasi. Hal ini disebabkan oleh adanya perubahan dominasi arah perambatan gelombang bunyi. Pada frekuensi 43 Hz dan 147 Hz diperoleh penurunan suhu terbesar yaitu (4,0 plus minus 0,5) derajat Celsius. Selain itu, diperoleh juga hasil bahwa besar penurunan suhu sisi dingin dan kenaikan suhu sisi panas regenerator berbanding lurus dengan kenaikan daya listrik masukan loudspeaker. Karena eksperimen ini tidak menggunakan komponen penukar kalor panas (hot heat exchanger) di sisi panas regenerator, daya listrik masukan dibatasi hanya sampai 60 W untuk menghindari aliran kalor balik dari sisi panas ke sisi dingin regenerator.

A research on the influences of regenerator position, sound frequency and input electric power to the performance of a traveling wave thermoacoustic refrigerator has been conducted. The traveling-wave thermoacoustic refrigerator consists of a regenerator, a loop-tube, and a loudspeaker. In this experiment, it has been made two units of regenerators which the length of each regenerator is around of 4 cm. The regenerator was made by stacking layer by layer of some stainless-steel wire-mesh screens which has the size of #40 and #50. The loop-tube are was made of a commercial PVC (polyvinyl chloride) pipe which has of 55.0 mm inner diameter and 2.6 mm wall thickness. The loudspeaker, which has diameter of around 10" and impedance of 4 ohm, is connected to the PVC loop tube by using of 15 cm straight PVC pipe. The location of regenerator in the loop-tube was varied in order to determine the optimal location. The 0.1 regenerator's normalized-position produces the largest temperature decrease is of around of (3.6 plus or minus 0.5) degree Celsius . By varying the sound frequency in a wide range, i.e. 30 Hz - 400 Hz it was found that the cold and hot side's position on regenerator was reversed. It was caused by the change of the dominant direction of the sound wave propagation along the looped-tube. At the frequencies of 43 Hz and 147 Hz, it was obtained the largest temperature decrease of around (4.0 plus or minus 0.5) degree Celsius. In addition, it was also found that the largest temperature decrease at cold side and temperature increase at hot side were proportional to the increase of the input electric power of the loudspeaker. Because in this experiment a hot heat-exchanger was not installed at the hot-end of regenerator, the input power was limited up to 60 W to avoid heat flowing back from the hot-end to the cold-end of the regenerator.

Kata Kunci : pendingin termoakustik, gelombang berjalan, lokasi regenerator, frekuensi bunyi, daya masukan