円管内強制対流沸騰におけるDNB発生過程のドライパッチと三相界面の挙動について

抄録

Experimental observations on the trigger mechanisms for the departure from nucleate boiling in subcooled flow boiling in a vertical, single-tube with an inner diameter of 4 mm and heated length of 5 mm are presented. In this study, a transparent heated tube is used. The tube is made of Pylex glass which inner wall is covered with extremely thin gold film, and it can be measured the inner wall temperature and observated flow behaviour simulataniously. Experiments used FC-72 as a test fluid are counducted under the conditions of G=400-1000 kg/m²s, ΔT_sub=30 K, q_in=464-673 kW/m². Three indicators, dry patch area, three-phase interfacial length and two-dimensional projected gas-liquid interfacial area (2D-PGIA) are drived from high-speed images. 2D-PGIA that is proposed in this study is a new indicatior, it can be considerd as a simple expression of interfacial area concentarion. The results indicate the possibility that the reduction of 2D-PGIA at constant heat flux condition is the trigger of DNB.