Numerical study on two-phase flow and heat transfer characteristics of loop rotating heat pipe for cooling motorized spindle

Abstract

• Rotating heat pipe with two bended structures was numerically studied. • Two-phase flow and heat transfer characteristics of the loop rotating heat pipe were investigated. • Effects of rotation speed and heating power were analyzed. Rotating heat pipe has a broad application prospect for the heat dissipation of high-speed rotation machineries. In order to realize the numerical simulation of a loop rotating heat pipe with two bended structure, which aims to cool the shaft of the high-speed motorized spindle, the Volume of Fluid (VOF) method combined with the Lee phase change model is adopted and the conjugate heat transfer between the fluid and the solid region is considered in this paper. The effects of heating power and rotation speed on flow behavior and heat transfer characteristics have been studied. Detailed evaporation and condensation phenomena are captured by simulation results. The results show that the centrifugal force has an inhibition effect on bubbles growth. Meanwhile, the increase of rotation speed enhances the convective heat transfer in the evaporator and speeds up the reflux of the condensing film and reduces the liquid film thickness in the condenser. The thermal performance of the loop rotating heat pipe is improved with the increase of rotation speed. When the rotation speed increases from 2000 rpm to 6000 rpm and 10,000 rpm, the overall thermal resistance is reduced by 30.0% and 36.8%, respectively. The overall thermal resistance is also reduced with the increase of heating power. When the heating power increases from 30 W to 120 W and 200 W, the overall thermal resistance is reduced by 31.0% and 37.0%, respectively. However, the temperature difference between the evaporator and the condenser increases with the increase of heating power while it decreases with the increase of rotation speed.