Research Of Heat Transfer Performance Of Internally Helical Ribbed Tube With Thin Wall

As a highly efficient heat transfer component, the internally helical ribbed tube is widely applied to the refrigeration and air conditioning, petrochemical, energy power and other fields, has the advantages of high heat transfer efficiency, low cost, compact structure etc., so the heat exchange performance of the internally helical ribbed tube has become a research focus for scholars at home and abroad. This paper does research on the heat exchange performance of the internally helical ribbed tube from two aspects of heat transfer and flow.This paper takes the common smooth tube and different geometric parameters of internally helical ribbed tube as the object of study, the medium in the tube for air, it does a basic hypothesis for the flow and heat transfer model of the fluid in the tube: the fluid in the tube can not be compressed, the three-dimensional steady laminar flow is fully developed in the tube, physical parameters are not changed with the external factors, ignoring the fluid viscous dissipative force and physical strength in the process of calculation, not considering the axial heat conduction. In the constant wall temperature boundary conditions, three-dimensional numerical simulation on the heat transfer and flow characteristics of the laminar flow condition is established.The results of numerical simulation of the common smooth tube and 18 internally helical ribbed tubes of the same tooth height are analyzed. In the range of the inner spiral angle γ for 30 °~45 °, thread number N for 30~46, tooth height H for 0.2~0.6 mm, the change regulation of Nusselt number and drag coefficient, and the impact of temperature field, which can be obtained, comparing to heat transfer performance of the smooth tube, heat transfer effect of internally helical ribbed tube is analyzed comprehensively by using the heat transfer evaluation criteria. The simulation results show that the effect of tooth height for heat transfer and flow is the largest, next is the inner spiral angle, the smallest influence is the thread number.For tooth height difference 0.1 mm,0.2 mm,0.3 mm,0.4 mm of high and low tooth internally helical ribbed tube, the heat transfer and flow characteristics of laminar flow condition are simulated, comparing to the corresponding approximately same inner surface area of equal tooth height internally helical ribbed tube, in the unchanged low tooth height of high and low tooth internally helical ribbed, the influence law of Nusselt number and drag coefficient for high tooth height increasing is summarized, and heat transfer performance of internally helical ribbed tube is analyzed comprehensively by using the Heat transfer evaluation criteria. The results show that, in the same internal surface area of heat transfer, the Nusselt number Nu, drag coefficient f of high and low tooth internally helical ribbed tube is bigger than equal tooth height, and the comprehensive effect of heat transfer of high and low tooth internally helical ribbed tube is better.