Enhanced evaporation heat transfer of water and R-11 falling film with the roll-worked enhanced tube bundle

Abstract

An experimental study was carried out for the evaporation heat transfer of water and R-11 falling films across horizontal smooth tube and two kinds of structured tube bundles under atmospheric pressure. The experimental results reveal that the low-cost roll-worked tube can greatly enhance the falling-film evaporation heat transfer either for water or for R-11 at low and moderate heat fluxes. The average evaporation heat transfer coefficients for the roll-worked tube bundle are basically independent of the falling film mass flow rate, the heat flux and the geometry parameters of the tube bundle, but only rely on the kind of liquids in the convective evaporation regime.