Browsing by Author "Chang, Wen-Yao"

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Evaluating the performance of a portable water-mist fire extinguishing system with additives
(2008-11-01)
Chang, Wen-Yao
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Fu, Ping-Kun
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Chen, Chiun-Hsun
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Shu, Yi-Liang
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機械工程學系
This study investigates how high-pressure water-mist system discharge methodologies influence the fire extinction performance for pan pool fires and the corresponding mechanisms of restraining fire. The fire source is a pool-fire burner. Fine water spray is injected using a portable device. The additive in the water-mist is neither toxic nor corrosive. All the tests are regarded as fuel controlled. The fire test parameters are fuel type, nozzle discharge angle, and additive solution volume. The fuels used are heptane, gasoline, and diesel. Nozzle discharge angles are 30, 45, and 60 degrees with respect to the ground. Additive solution volumes are 0% (pure water), 3, 6, and 10%. Test results indicate that the nozzle discharge angle and additive solution volume in a water-mist fire extinction system play a significant role. Fire extinguishing efficiency is influenced by mist effects and the additive. Furthermore, the water-mist system can reduce radiation and can provide good protection for operators using portable fire extinguishing equipment. Copyright (C) 2008 John Wiley & Sons, Ltd.
Performance evaluation of a water mist system in semiconductor wet bench fires
(2008-05-01)
Chang, Wen-Yao
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Fu, Ping-Kun
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Chen, Chiun-Hsun
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Shu, Yi-Liang
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機械工程學系
Wet benches are typically utilized in semiconductor facilities for wafer and parts cleaning. Heaters and some flammable liquids, such as acetone and isopropyl alcohol (IPA), are employed during the cleaning process. Wet bench fires have caused serious losses in the semiconductor industry. To assess the fire protection performance, several field tests were performed using a water mist system installed in the wet bench. In this study, acetone pan fuel was used as fire source. The test parameters were operational pressure, pan size, nozzle location, cylinder obstruction and degree of door closure. An appropriate design for operating pressure and the location of water mist nozzles extinguished wet bench fires effectively in the early fire stages. The nozzles are suggested to be fixed above or on the each side of the pan, ensuring that mist can completely cover a pan surface with sufficient momentum. With this suggested design, fires can be extinguished in the pan and do not spread over the wet bench. (c) 2007 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Performance evaluation of portable water mist fire extinguishing system
(2006)
Chang, Wen-Yao
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Fu, Ping-Kun
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Chen, Chiun-Hsun
;
Shu, Yi-Liang
;
機械工程學系
The phase out of Halon production under the Montreal Protocol has led to intense research to find a replacement agent for fire protection. Through extensive research and testing, water mist systems have gained worldwide acceptance as an effective solution in many applications. In this article, we will introduce a portable water mist system, with longer operating time than traditional fire extinguisher and less water damage than hydrant. The operation time of traditional fire extinguisher is always ten to thirty seconds, too short for fire control and dangerous to operator. If the fire is getting larger, hydrant will be used, and always results in huge water damage, especially in high-tech facilities. So, it's necessary to find a system with longer operation time to control fire and less water used for water damage problem, especially for high-tech facilities. This portable extinguish system is designed to operate at least ten minutes, long enough for fire control, and this system uses high pressure water mist nozzle, less water used, the water damage will not be a problem. This Portable system uses a petrol engine or an electric engine to pump water for high pressure operation. The petrol one could be used out of buildings, and electric one could be used in buildings without air pollution problem, which is important to employees and high-tech manufacturing instruments. There is a mist nozzle with one hose connects to the system and this soft pipe could be 50 meters long, could easily move to the fire origin and releases mist to fire. Series of fire tests were taken for evaluating the performance of this portable system. In fire tests, air temperatures, images, combustion products and extinguish time are recorded simultaneous. The fire tests include wood stabs fire, sofa fire, petrol pan fire, motorcycle fire and car fire. In these fire tests, the portable water mist system performs well and meets what we need, longer operation time and less water damage. This portable system also has capability to cool the environment temperature and wash down combustion products and soot, it's safer to operator.
Probing nanocrystalline grain dynamics in nanodevices
(2017-06-01)
Yeh, Sheng-Shiuan
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Chang, Wen-Yao
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Lin, Juhn-Jong
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電子物理學系
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物理研究所
Dynamical structural defects exist naturally in a wide variety of solids. They fluctuate temporally and hence can deteriorate the performance of many electronic devices. Thus far, the entities of these dynamic objects have been identified to be individual atoms. On the other hand, it is a long-standing question whether a nanocrystalline grain constituted of a large number of atoms can switch, as a whole, reversibly like a dynamical atomic defect (that is, a two-level system). This is an emergent issue considering the current development of nanodevices with ultralow electrical noise, qubits with long quantum coherence time, and nanoelectromechanical system sensors with ultrahigh resolution. We demonstrate experimental observations of dynamic nanocrystalline grains that repeatedly switch between two or more metastable coordinate states. We study temporal resistance fluctuations in thin ruthenium dioxide (RuO2) metal nanowires and extract microscopic parameters, including relaxation time scales, mobile grain sizes, and the bonding strengths of nanograin boundaries. These material parameters are not obtainable by other experimental approaches. When combined with previous in situ high-resolution transmission electron microscopy, our electrical method can be used to infer rich information about the structural dynamics of a wide variety of nanodevices and new two-dimensional materials.