Heat Transfer Enhancement at Vapor Condensation from a Vapor-Air Mixtures on Vertical Tubes

Heat transfer enhancement of water and gasoline vapors condensing from a vapor-air mixtures on vertical tubes was investigated. These tubes had transverse annular grooves on the outside surface and diaphragms on its inside surface. An up to 1.9-fold increase of heat transfer in water vapor condensation and an up to 1.7-fold increase at condensing of gasoline vapors with an air content up 6% were obtained. The obtained heat transfer enhancement by turbulators compared with the heat transfer decrease due to the presence of air amounting to 6%. The ratio of heat transfer coefficients on tubes with grooves and those on smooth tubes increases as the rolling groove depth increases and the rolling pitch decreases.

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