Author(s)

S. Sinkunas, J. Gylys & A. Kiela

Abstract

The aim of the present study is to clarify the tendencies of the heat transfer developments in gravitational liquid film flow. Heat transfer in a turbulent film flow on a vertical tube has been investigated in this paper. The analytical study of stabilized heat transfer of turbulent film has been performed. The calculation method for the local heat transfer coefficient of turbulent film falling down a vertical convex surface is proposed. The analytical approach is used to establish the dependence of heat flux variation on the distance from the wetted surface. An experimental investigation of heat transfer in the entrance region of the turbulent film has also been carried out. The methodology involves determining the local heat transfer coefficient and establishing the transfer stabilization length. The description of the experimental set-up and procedure is presented in this study. The experiments have been performed in water film flowing down a surface of vertical tube for Reynolds number ranged from 5850–6700. The results of experiments are discussed with respect to the local heat transfer dependence on the Reynolds number and initial velocity of the film in liquid distributor. Key words: heat transfer, gravitational liquid film flow, turbulent film, entrance region, vertical tube. 1 Introduction A lot of industrial processes in chemical, environmental and power engineering employ gravitational liquid film systems that are often designed using the heat transfer phenomena in flows. The application of stabilized liquid film flow in industrial apparatus is perspective from both economic and engineering aspects.

Keywords

heat transfer, gravitational liquid film flow, turbulent film, entrance region, vertical tube.