碩士 / 國立成功大學 / 機械工程學系 / 87 / Experiments are conducted to measure and analyze the thermal-hydraulic characteristics of plate finned-tube evaporators under frosting conditions for different fin pitches (3,6 fins per inch) , different outside tube diameters (1/2,5/16 inch),and different operating conditions( i.e., different air velocity, ambient temperature, ambient relative humidity ratio and tube wall temperature). The variations of the heat transfer rate , overall heat transfer coefficient , pressure drop, frost thickness and air volume flow rate are recorded and compared.
The experimental results indicated that as the ambient temperature、relative humidity ratio and air velocity are increased , or the tube wall temperature is decreased ，the frost thickness is increased. Heat transfer rate and overall heat transfer coefficient start to decrease after the frost thickness 0.4~0.6 mm. Frost formation also makes pressure drop increase, and makes air volume flow rate decrease. It is also shown that evaporator with sweat fin pitch makes heat transfer performance decrease faster than large one; small tube outside diameter makes frost formation faster then large one.
| Identifer | oai:union.ndltd.org:TW/087NCKU0489021 |
| Date | January 1999 |
| Creators | HUAN CHUAN TSENG, 曾煥全 |
| Contributors | JIN YUH JANG, 張錦裕 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 84 |
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