Investigation on Heat Transfer Performance of Loop Thermosyphon for Inner Cooling of Motorized Spindle

Taking the inner cooling of 150SD grinding motorized spindle as the application background, an innovative cooling method based on the single-loop thermosyphon with high heat transfer efficiency and without external power supplier is suggested, which could avoid the troublesome rotary seal problem on the inner cooling for spindle shafts. In view of the fact that loop thermosyphon is suitable for the cooling space of the spindle shaft, n-pentane is used as the working medium, and the theoretical analysis on the flow and heat transfer characteristics of the working medium in a single-loop thermosyphon under high centrifugal force is conducted, then an experimental study on the heat transfer performance is carried out. The results show that the operating temperature of the single-loop thermosyphon is stable under the experimental condition and the heat transfer performance reaches its peak value when the filling rate is 60%, and the corresponding thermal resistance is only 0.57℃/W. The temperature rise of rotor in 150SD grinding motorized spindle is 28.5℃, and the temperature rise continuously decreases with the increase of rotary speed. Therefore, the single-loop thermosyphon may have promising application to the inner cooling of motorized spindles.