CALCULATED HEAT TRANSFER DEPENDENCIES AND AERODYNAMIC RESISTANCE OF SCREW-TYPE TUBES

Abstract

The paper presents the results of CFD simulation of convective heat transfer and aerodynamic drag during internal flow in pipes with an equidistant surface in the range of Reynolds numbers from 3500 to 13000. Heat exchanger sections composed of such pipes have improved thermal efficiency compared to heat exchange sections that are composed of steel pipes of round profile. The use of such pipes, with the same power spent for moving the heat carrier inside the pipes, will allow to reduce the metal consumption of the heat exchanger by 30 ... 40% in comparison with the heat exchanger made of traditional smooth tubes of round profile. This is achieved due to a high degree of intensification of heat exchange inside the pipe and by decomposition of the pipe surface. In addition, for the manufacture of such pipes, the use of a relatively inexpensive technology is envisaged-roller rolling around a round pipe using a flowing medium or liquid for counterpressure inside the pipe. The proposed technology and equipment for the profiling of screw pipes with an equidistant surface makes it possible to produce such pipes up to 6 m in length.

Generalizing relationships are proposed for calculating the convective coefficients of heat transfer and aerodynamic drag of equidistant screw-shape surface, taking into account the effect on the heat transfer intensity and resistance of the geometric parameters of the pipe and regime flow factors.

Generalized computational dependencies for determination of heat transfer coefficients and aerodynamic resistance inside brass screw-shaped pipes with an external diameter of 16 mm are obtained, taking into account the effect on the heat exchange intensity and resistance of the geometric parameters of the pipe and regime flow factors.

On the basis of the generalizing dependences obtained, it will be possible to develop new engineering methods for calculating heat transfer coefficients and aerodynamic drag inside the equidistant screw-shape pipes.