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Film boiling of nitrogen with suction on an electrically heated porous plate
Author(s) -
Wayner P. C.,
Bankoff S. G.
Publication year - 1965
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690110115
Subject(s) - boiling , materials science , heat transfer , liquid nitrogen , heat transfer coefficient , superheating , nucleate boiling , heat flux , nusselt number , thermodynamics , porosity , composite material , porous medium , chemistry , reynolds number , physics , turbulence , organic chemistry
Experimental equipment to study the film boiling of liquid nitrogen on a porous heat source with vapor suction was developed. The electrically heated element was a 3.69 in. sintered stainless steel screen, which was also used as a resistance thermometer in conjunction with an a.c. potentiometric circuit. In preliminary work, this mode of heat transfer was unstable, but stability was achieved by placing a porous flow control element on the liquid side of the heater. It was found that the Nusselt number was a function of only the Reynolds number; the heat transfer coefficient was increased by a factor of as much as 2.5 over the heat transfer coefficient in normal film boiling; it was possible to vary independently any two of the three variables, heat flux, flow rate through the plate, and temperature difference; and the generated vapor was considerably superheated. Fluctuations in the local surface temperature were measured in film boiling from both porous and nonporous flat plates, indicating that momentary solid‐liquid contacts can occur, for all practical purposes, in film boiling.