碩士 / 國立勤益科技大學 / 冷凍空調系 / 101 / The heat transfer and pressure drop performance of X type louver fin and tube heat exchangers are studied. The plate type and curved shape heat exchangers characteristics are compared to provide design reference of louver fin and tube heat exchangers. The geometries of the fin and tube heat exchangers are: one-row and two-row, the longitudinal tube pitch is 12.7mm, the transverse tube pitch is 21mm, the tube collar is 7.3mm, the fin thickness is 0.1mm, two fin pitches Fp=1.5mm and Fp=2.5mm are studied. The louver pitch in the louver fin is 1.425mm, and the louver width is 1.425mm. the louver angle is 25°. Eight frontal velocities are considered: 0.5 m/s、1 m/s、1.5 m/s、2 m/s、2.5 m/s、3 m/s、3.5 m/s、4.0 m/s. Three curvatures 60mm、100mm and150mm of the circular heat exchangers are studied.
The results show that the plate type and circular fin and tube louver fin heat exchangers have similar heat transfer characteristics with respect to the same pressure drop and air volume. When the fin pitch becomes smaller, the heat transfer and pressure drop of the louver fin will increase simultaneously due to the trans-louver air flow. The heat exchanger with the same frontal velocity will have approximately same heat transfer rate, but the pressure drop in the Fp=1.5mm is about twice of the Fp=2.5mm. The heat transfer rates of the bare tubes in the heat exchangers have proportional to the area percentage of the total heat transfer surface. It seems that the bare tube primary heat transfer surfaces have no extra heat transfer with respect to the extended fin.
Under the same pressure drop, the heat transfer rate difference between the single row plate type and curved heat exchanger reaches 5% at low velocity. The difference becomes large in the two row heat exchanger and approximately 10% at low velocity. The heat transfer rate discrepancy becomes smaller as the air velocity increased, about 3% in the two row Fp=1.5mm heat exchanger.
| Identifer | oai:union.ndltd.org:TW/101NCIT5680010 |
| Date | January 2013 |
| Creators | Hsin-Wei Chen, 陳欣緯 |
| Contributors | Wen-Chien Hsieh, 謝文健 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 111 |
Page generated in 0.0112 seconds