Hydro-thermal performance of cracking furnace tube equipped with internal helix with different twist ratio

Abstract Spiral tape is a technology widely used to enhance heat transfer. In the present paper, an open spiral tape was designed to obtain good heat transfer performance. A comparative study between this type and ordinary spiral tape was performed numerically in tubular flows. The results show that the tubes with ordinary spiral tapes and open spiral tapes can produce strong radial force on the fluid, which can effectively change the flow state and turbulence degree of the fluid, so as to effectively strengthen the heat transfer. As the twist ratio increases, the temperature uniformity and maximum temperature in the tube have not been progressively improved and increased. The decrease of twist ratio is conducive to improving the influence range of spiral plate and enhancing the heat transfer effect, but it will increase the flow resistance and improve the resistance coefficient. When the twist ratio is 3, the thermal performance factor of the tube with open spiral tape can be enhanced by 22-25% as compared with the spiral tape of the twist radio is 1. All these demonstrated that open spiral tape is a promising technology to enhance convective heat transfer.