ABSTRACT
A data base was obtained for ultra-high CHF, with values mostly exceeding 104 W cm-2, using high mass velocity water flow through small diameter tubes. The parametric trends of ultra-high CHF were ascertained with respect to key flow and geometrical parameters over a wide range of exit pressures. Pressure drop for most conditions was fairly constant over the entire range of heat fluxes, from the single-phase flow condition corresponding to zero heat flux up to CHF, proving CHF was triggered even with negligible net vapor production. CHF increased with increasing mass velocity, increasing subcooling, decreasing tube diameter, and decreasing heated length. CHF increased with increasing pressure up to about 30 bars, became fairly constant up to about 100 bars, and then decreased for higher pressures. A new CHF correlation was developed for pressures ranging from 10.3 to 172.4 bars corresponding to CHF values as high as 2.76 × 104 W cm-2.
