Boiling Heat Transfer Characteristics of Subcooled Nitrogen

The boiling heat transfer characteristics of saturated and subcooled nitrogen were investigated to clarify the effect of subcooling. The objective of this study is to supply information on the cooling design of high-Tc superconducting apparatuses such as the high-Tc super-conducting transformer. A thin wire of platinum-30% rodium with a diameter of 0.05mm was simultaneously used for the heater and the thermometer. The effect of space restrictions around wire on heat transfer characteristics was also examined by using transparent acrylic tubes covering thin wires, which simulated the complicated structure of a cooling system for high-Tc superconducting apparatuses. The heat transfer characteristics of subcooled nitrogen were compared with those of saturated nitrogen, and it was found that heat transfer was remarkably enhanced with the degree of subcooling.