THE INCEPTION OF NUCLEATE BOILING WITH LIQUID NITROGEN.
Abstract
Delayed inception of nucleate boiling and patchwise boiling are discussed and the significant parameters restricting the growth of a boiling patch are analytically determined to be: (1) a high nucleate boiling heat transfer coefficient; (2) a low total heat flux; (3) the absence of cavities with a trapped liquid-vapor interface outside the boiling patch; (4) an appropriate value of wall thermal conductivity; (5) a high vapor enthalpy per bubble. A qualitative agreement between theory and experiment was observed for items 1, 2, 3 and 4. A series of pool boiling tests were conducted at one atmosphere of pressure in order to develop a surface finish that would eliminate the observed temperature hysteresis at inception of boiling of liquid nitrogen. The best surface finish developed used a bi-metallic (Zm + Cu) flame spray process. The flame spray and a 0.3-micron-grit polished copper surface were tested for their nucleation properties in forced flow of liquid nitrogen. Visual observations indicated that nucleation occurred promptly on both surfaces at approximately the same wall temperature. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1966
- Accession Number
- AD0634256
Entities
People
- David W. Almgren
- Joseph L. Smith Jr.