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Author
Klassen, M. E. | diMarzo, M.
Title
Transient Cooling of a Hot Surface by Droplets Evaporation. Final Report. July 1988-July 1989.
Coporate
Maryland Univ., College Park
Sponsor
National Institute of Standards and Technology, Gaithersburg, MD
Report
NIST GCR 90-575; Report 89-3, May 1990, 108 p.
Distribution
Available from National Technical Information Service
Contract
70NANB8H0890
Keywords
droplets | evaporation | solid fuels | thermal conductivity | water | vaporization
Abstract
An infrared thermographic technique is developed to obtain the transient solid surface temperatures surrounding the droplet during vaporization. This technique is appealing because it is non-intrusive, detailing the surface response to the droplet without affecting the evaporation process. Surface recovery can also be monitored using this thermographic method. The transient temperature distribuiton of a Macor solid is detailed. It is found that contact temperature is held in the vicinity of the droplet during the majority of the droplet's evaporation until the droplet thickness diminishes greatly, where upon the temperature of the solid surrounding the droplet begins to rise. The non-dimensional radius of influence of droplet cooling is also detailed. The data obtained on the cooling effect induced on aluminum and on Macor from previous studies is used in concert with new data obtained on a quartz surface to characterize the induced cooling of a hot surface by an evaporating droplet. The role of the droplet size and shape is investigated for various high and low thermal conductivity surfaces. Droplet evaporation time, surface heat transfer coefficient and droplet shape parameter are also examined.