Modeling of spray cooling of superheated surfaces
- National Research Council, Moffett Field, CA (United States). NASA Ames Research Center
This paper considers flow of an aerosol containing liquid droplets around a body. Body surface temperature exceeds the boiling point of the liquid. Depending on droplet normal impact velocity, impinging droplets are either captured by the surface and eventually evaporate, or they are almost elastically rebound. This alteration in droplet behavior causes the onset of a heat transfer crisis. Spray cooling heat transfer can be described in terms of two problems. The first problem consists of an analysis of the dynamic Leidenfrost phenomenon and a subsequent calculation of the critical droplet normal velocity as a function of physical and process parameters. The second problem involves determining the field of droplet trajectories around the body based on a modified theory of inertial capture of suspended aerosol particles and the subsequent calculation of total liquid mass flux to the body surface. Both these problems are effectively resolved for bodies of different shape in a uniform aerosol flow and for a mist jet normally falling onto a plate. A natural explanation is given for the heat transfer crisis as surface temperature increases within a certain interval, and the surface distribution of the specific heat removal coefficient due to droplet evaporation is obtained. The developed model agrees well with experimental evidence, both qualitatively and quantitatively.
- OSTI ID:
- 435749
- Report Number(s):
- CONF-951135-; ISBN 0-7918-1755-5; TRN: IM9710%%407
- Resource Relation:
- Conference: 1995 International mechanical engineering congress and exhibition, San Francisco, CA (United States), 12-17 Nov 1995; Other Information: PBD: 1995; Related Information: Is Part Of Proceedings of the ASME Heat Transfer and Fluids Engineering Divisions: Fluid mechanics and heat transfer in sprays; Heat, mass and momentum transfer in environmental flows; Measurement techniques in multiphase flow; Multiphase transport in porous media. HTD-Volume 321; FED-Volume 233; Hoyt, J.W. [ed.] [San Diego State Univ., CA (United States)]; O`Hern, T.J. [ed.] [Sandia National Labs., Albuquerque, NM (United States)]; Presser, C. [ed.] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)] [and others]; PB: 761 p.
- Country of Publication:
- United States
- Language:
- English
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