A mechanistic model for critical heat flux of subcooled flow boiling
This paper presents a mechanistic model for the prediction of CHF of subcooled flow boiling based on liquid sublayer dryout model. In the model, By writing critical wavelength of Helmholtz Instability to both left and right sides of vapor blanket and by assuming these two wavelengths are equal to each other, the vapor blanket velocity U{sub B} can be written as a simple function of average velocity of liquid bulk V{sub {ell}} which can be obtained by the knowledge they have known. Then, on the base of U{sub B}, other important parameters such as vapor blanket length L{sub B} and liquid sublayer thickness {delta} can be calculated easily. The model is simple with explicit physics nature, and is characterized by the absence of empirical constants. To verify the present model, two databases (include about 2,400 points) are used. One gathered by Celata used to verify his model is characterized by high mass velocity and low-medium system pressure. The other gathered by Pei is characterized by high pressure and low-medium mass velocity. The verification showed that present model could keep its validity in a wide range of operating conditions (mass velocity up to 70 Mg/m{sup 2}s, system pressure up to 17.5 MPa). Figure A-1 shows a comparison of calculated versus experimental CHF. About 89% of data points are predicted within {+-}30%. Comparison between Celata model and the present model shows that although present model shows a little worse prediction than Celata model with the data base collected by Eclat, it shows a much better prediction with the data base collected by Pei. A general better prediction than Celata model is obtained with both the databases collected by Celata and Pei.
- Research Organization:
- Univ. of Tsukuba, Ibaraki (JP)
- OSTI ID:
- 20026816
- Resource Relation:
- Conference: 5th ASME/JSME Thermal Engineering Joint Conference, San Diego, CA (US), 03/14/1999--03/19/1999; Other Information: 1 CD-ROM. Operating system required: Windows i386(tm), i486(tm), Pentium (R) or Pentium Pro, MS Windows 3.1, 95, or NT 3.51, 8 MB RAM, MacIntosh and Power MacIntosh with a 68020 or greater processor, System software version 7.1, 3.5 MB RAM (5 MB for PowerMac) 6 MB available hard-disk space, Unix; PBD: 1999; Related Information: In: Proceedings of the 5th ASME/JSME thermal engineering joint conference, [3600] pages.
- Country of Publication:
- United States
- Language:
- English
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