The effect of condensation area and operating temperature on heat transfer capacity of a closed loop thermosyphon cooling system for HTS machinery

A sophisticated cooling system is necessary for applications of high-temperature superconductor (HTS) for electric devices. Among them, status of rotating machine requests to maintain the temperature of HTS field poles under 40 K. We have employed a thermosyphon (TS) as cooling system for HTS rotating machines. The TS cooling is based on natural convection of coolant and does not require a forced circulation. Advantages of the TS cooling system are simple, light weight mechanical composition and high heat transfer coefficient with latent heat. The operating temperature of the TS cooling system depends on the saturation temperature and the pressure of coolant. Thus, the saturation pressure of the TS affects the performance of the TS cooling system. In this paper, we investigate the relationship between the saturation pressure and the condenser heat transfer area. We studied a heat transfer capacity under the heat load with different neon quantities using the TS cooling system. The saturation pressure increases with the heat load and/or condenser temperature increment. Reducing the number of condensers i.e. decrease of condensation area, the saturation pressure increases and the heat transfer capacity decreases. This result shows that the saturation pressure is proportional to the temperature difference between condenser temperature and the saturation temperature calculated by saturation pressure.