Accession Number : AD0668986

Title :   DROPWISE CONDENSATION OF STEAM AT ELEVATED PRESSURES.

Descriptive Note : Technical rept.,

Corporate Author : MASSACHUSETTS UNIV AMHERST DEPT OF CHEMICAL ENGINEERING

Personal Author(s) : Dolloff,J. B. ; Metzger,N. H.

Report Date : 15 MAY 1968

Pagination or Media Count : 42

Abstract : The results of a study of the mechanism of dropwise condensation of steam at elevated pressures are presented. Equivalent heat transfer coefficients for dropwise condensation of steam were determined experimentally for pressures ranging from 0 to 142 psig. The results showed that for each Delta-Ts there is a pressure at which the film coefficient is a maximum and that this maximum increases slightly as Delta-Ts decreases. For a Delta-Ts of 10 and 20 F, the maximum heat transfer coefficient is 33,000 and 24,000 Btu/hr-sq. ft.-F respectively and lies in the pressure range 50-60 psig. It is believed that this maximum reflects the formation of a quasi-film of closely packed drops which offers considerable resistance to heat transfer. Photographic analysis of the dropwise condensation phenomena revealed that the combined effects of drop cycle time, free area available for condensation, and overall temperature driving force are the factors which cause a maximum in the equivalent heat transfer coefficient. A theoretical analysis is presented which is consistent with experimental observations. Also, photographs revealed that dropwise condensation was maintained for pressures up to 120 psig. (Author)

Descriptors :   (*STEAM, *CONDENSATION), DROPS, HIGH PRESSURE, HEAT TRANSFER COEFFICIENTS, FILMS, PHOTOGRAPHIC ANALYSIS

Subject Categories : Industrial Chemistry and Chemical Processing
      Air Condition, Heating, Lighting & Ventilating
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE