An SEM surface study of nucleate pool boiling heat transfer to saturated liquid nitrogen reduced pressures from 0.1 to 0.9

"This study constituted an examination of both nucleate boiling and maximum heat flux characteristics of liquid nitrogen boiling from characterized surfaces. Several textures of gold plated copper surfaces were studied in addition to silver and silver oxide surfaces. Data were taken over a wide range of reduced pressures. All surfaces were examined using a Scanning Electron Microscope (SEM). Data and micrograph comparison revealed that both surface chemistry and surface roughness affect the nucleate boiling characteristics of liquid nitrogen. These effects are separated from each other showing that nucleate boiling is a function of both surface chemistry and topography. Surface roughness was found to have a significant effect on the maximum heat flux with rougher surfaces yielding higher heat flux values. The temperature difference at burnout was found to be a function of both surface chemistry and roughness. Some existing correlations for both nucleate boiling and maximum heat fluxes were examined and shown to inadequately predict the data, primarily because of inability to account for surface roughness and/or surface-fluid interaction as affected by surface chemistry. A maximum temperature difference correlation tested predicted burnout temperature differences well. The necessity to age a surface in the fluid to be boiled was found not to be a result of adsorbed gases, but probably a result of impurities acquired on the surface that must be removed. Attempts to observe hysteresis is were unsuccessful. Hysteresis was found not to be a function of adsorbed inert gases. Data indicated that one mechanism of heat transfer by nucleate boiling will not suffice for all pressures. An existing nucleate boiling correlation was modified to allow for a mechanism change and predicted the data better than other correlations tested"--Abstract, pages ii-iii.

Name thesis:degree_name

Ph. D. in Chemical Engineering

Grantor

University of Missouri--Rolla

Year dc:date.available

2016

Author dc:creator

• Porchey, David Virgil

• Chemical Engineering

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/2039

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-3041