Self-Circulating Evaporative Cooling System of a Rotor and Its Experimental Verification

Abstract

With the development of hydropower, the heat problem of a rotor cannot be ignored. This paper presents a topology of an evaporative cooling system for rotors. The system seals the pole coil in a tank and immerses the coil in the insulating coolant with a suitable boiling point. The latent heat of vaporization during the boiling of coolant is used to control the temperature rise of the pole coil. After explaining the circulation principle of the system, the effectiveness of the cooling system is verified by experiments. A small-scale experimental platform has been set up to test the effectiveness of the new topology. The comparison experiment with air-cooling shows that the phase change cooling system can not only provide hundreds of times the heat transfer capacity of air-cooling, but also the temperature rise of the coil is half that of air cooling. Based on the experimental results, the calculated formula of the heat transfer coefficient of the evaporative cooling system in the rotating state was fitted, and the deviation of the calculated result could be kept at less than 25%. Thanks to the evaporative cooling system, the rotor carries a high current density.