This thesis uses aluminum porous board (AP board) to study the noise reduction for cooling tower. It sets the barrier to isolate the sound propagation. But it will happen diffracted phenomenon when sound wave impinging at the edge of barrier. So the mathematical model of acoustic diffraction on the barriers, which is set up by Hayek, is applied in this thesis. Base on this theorem, the AP board and the paths of sound propagation are analyzed.
In experiment, it uses the sound intensity method to measure the cooling tower for determining the major source first. The major source is determined by ranking the sound power. And the suitable insulation material is selected by analysis the frequency band of major source. After analyzing, the major source of cooling tower is the region of fans by motor driven that is located upper the cooling tower. And its frequency range is between 25 Hz to 2500 Hz. So the AP board is a candidate since it has broadband characteristic on noise insulation.
After aim of the major source, the noise barrier is studied for noise reduction. In this thesis, the U profile of barrier (looking down from above), which considers the situation in the field, is designed to surround the cooling tower. This barrier is made of aluminum board, and the aluminum porous board is applied to add on the upper barrier for noise reduction. To study the acoustic diffraction on the boundary of barrier, the thick of porous board is added on the upper barrier. The insulation effect is compared in the different condition after measuring the transmission loss. The T shape barrier is also designed for noise reduction evaluating in this thesis. Finally, the best-insulated effect is obtained when the complex board is added on the upper barrier. And the noise level is down to 59 dB around the environment. This result is matched the EPA noise standards.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0716101-142041 |
| Date | 16 July 2001 |
| Creators | Cheng, Hao-An |
| Contributors | Shiuh-Kuang Yang, Ru-yen Ro, rcwei |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0716101-142041 |
| Rights | unrestricted, Copyright information available at source archive |
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