Study Of Liquid Film Formed Of Viscosity Liquid Outside Horizontal Tube

The zinc coating tubes are widely used in refrigeration equipment. Comparing with the coppered steel tubes, the zinc coating tubes have some important characters, such as low cost, long life and no pollution. But now the zinc coating technology not only makes the zinc coat not-uniformity but also consumes more energy. So it is very significant to study the liquid film formed of viscosity liquid outside horizontal tube.Based on the low Reynold number and small flux model, the purpose of the paper is to study the velocity and thickness of the liquid film outside the horizontal tube. According to the character of the object, the paper adopts cylinder coordinates and boundary layer coordinates, dimensionless parameters are adopted to simplify the governing equations and the main part of the question is grasped. The expressions of velocity and the first order partial differential equation of the thickness of liquid film are attained. The paper uses characteristic line method to achieve the numerical solution of liquid film and compares the results of two different coordinates. Heat-transfer character is analyzed and temperature curve is attained. The paper also designs experimental facilities.The result shows that the distributing law of liquid film is identical in two different coordinates, at special time the film thickness increases along circle direction and the fluctuation range of liquid film aggravates along with time. Because the tube radius is short and liquid film is very thin, the temperature of liquid film is only the time function and temperature curve is exponent curve.