碩士 / 華梵大學 / 機電工程研究所 / 89 / This thesis employs the experimental method to investigate the thermofluid performance of plate and louvered finned-and-tube heat exchangers under frosting conditions. The effects of various geometric and environment parameters on performance of heat exchangers have been examined in detail. The parameters include the number of rows, the temperature of inlet refrigerant, the air flow rate, the relative humidity and the temperature of inlet air.
The experimental results show that, under a fixed number of rows, in the beginning of frost deposition, the heat transfer rate increases with the flow rate, the temperature of inlet air and the relative humidity. If the relative humidity and temperature of inlet air are fixed to be 70%. The temperature of inlet air = 5℃, respectively, the variations of heat transfer rate, overall heat transfer and pressure drop with time are more significant. For the effects of row number, the heat transfer rate increases with the row number. But the effects of row number on the overall heat transfer coefficient show the inverse trend.
The performance comparisons between plate and louvered finned-and-tube heat exchangers under the same conditions indicate that the trend of heat transfer rate, overall heat transfer coefficient and air pressure loss are approximately the same. But the heat transfer performance of louvered type are better than plate type heat exchangers. As for the frosting on the pressure loss across the heat exchangers, the results show that larger pressure loss is noted for louvered finned-and-tube heat exchangers. This means that at the same time frosting period, the louvered type heat exchanger has more frost deposition.
| Identifer | oai:union.ndltd.org:TW/089HCHT0657005 |
| Date | January 2001 |
| Creators | Su, Yang-Bo, 蘇原保 |
| Contributors | Yan, Wei-Mon, 顏維謀 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 73 |
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