| Title |
Pressure Drop in Microtubes and Correlation Development |
| Keywords |
Microtube ; 마이크로관 ; Pressure drop ; 압력강하 ; Friction factor ; 마찰계수 ; Two- phase frictional multiplier ; 2상유동 마찰손실배수 |
| Abstract |
The characteristics about the pressure drop in microtubes have been investi-gated. The test tubes are the circular, seamless, stainless steel tubes with an inner diameter of 0.244, 0.430, and 0.792mm, respectively. R-134a was used as a test fluid. Early flow tran-sition which has been reported in some previous studies is not found in single-phase flow pressure drop tests. The conventional theory between friction factor and Reynolds number predicted the experimental friction factors within an absolute average deviation of 8.9%. The two-phase flow pressure drop increases for higher quality and mass flux, and for reduced in-ner diameter. The existing correlations fail to predict the experimental data. A new correlation to predict the two-phase flow pressure drop is developed in the form of the Lockhart- Martinelli correlation. The effects of the tube diameter and the surface tension were consi-dered, and the correlation predicted the experimental data within an average absolute deviation of 8.1%. |