Heat and mass transfer to decelerating finely-atomized sprays.

The transfer of heat, mass and momentum in the nozzle zone of sprays produced by internal-mixing, pneumatic and hollow-cone, pressure nozzles was determined for both co-current and cross-current drying air flow patterns. The Nusselt Numbers for the evaporating .drops were correlated by means of the equation proposed by Ranz and Marshall for stationary drops in a rnoving air flow. Values of the drag coefficients for the decelerating drops, over a range of Reynolds Numbers of 1 to lOO, were approximately one tenth of those predicted by the standard curve for spheres, and a dependance on the drop diameter was observed. Methods of measuring the physical properties of the water-air system were developed and tested with special attention devoted to the determination of drop velocities and air humidity