Performance of air/spray cooling system for large-capacity and high-power-density motors

Nowadays, the motors in many fields show the development trend of large-capacity and high-power-density, putting forward the higher requirements for motor cooling. In this paper, a new cooling technology for horizontal motor was proposed, called air/spray cooling technology, which use the mixture of air and the high-insulation spray as the cooling medium. Relying on the compound heat exchange form including single-phase convection and evaporation, air/spray cooling technology has good cooling capacity. An experimental model of the air/spray cooling system was established on the basis of a real turbine-generator. The experimental results show that under the experimental conditions, the maximum temperature of the air/spray cooled stator coils can be 22 degrees C lower than that of the air-cooled stator coils. Compared with the air-cooled stator coils, the utilization of air/spray cooling technology can make the temperature distribution of the stator coils more uniform in the circumferential direction of the motor and the average heat transfer coefficient can be increased by 28% to 53%. The increase of the spray medium mass flow can cause the temperatures of the stator coils decrease gradually and the air/spray mixture mass flow increase, resulting in the demand for a higher driving force of system.