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An experimental investigation of heat transfer to water in film flow Part I – non‐boiling runs with and without induced swirl
Author(s) -
Herbert L. S.,
Sterns V. J.
Publication year - 1968
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450460604
Subject(s) - tube (container) , thermodynamics , mechanics , heat transfer , reynolds number , materials science , thermocouple , heat transfer coefficient , boiling , heat flux , flow (mathematics) , chemistry , turbulence , composite material , physics
Local heat transfer coefficients have been measured in the range of Reynolds Numbers 3,000‐20,000 for non‐boiling heat transfer to water flowing down the inside of a copper tube. The tube was 0.948‐in. Inside diameter and 8‐ft long, heated in 15 sections 6‐in. long, by electrical resistance heaters wound on the outside of the tube. Thermocouples measured the wall temperature at the midpoint of each section. Coefficients obtained for downward, non‐swirling, full tube flow were correlated by the Dittus Boelter equation, with a correction for heat flux. An experimental correlation was obtained for the improved coefficients resulting from the use of a swirl generator in full tube flow. Non‐swirling falling film data were correlated by an equation: h LA = 3.9 Re LA 0.05 It is to be noted that the exponent on Re LS is higher than the value of 0.1‐0.33 found by previous workers. The effect of swirl on falling film heat transfer was complex; increased coefficients were noted at ReL below 10,000 but much reduced coefficients were obtained at R L above 15,000 in the lower parts of the tube.