垂直円管内の自然流動沸騰系の限界熱流束

概要

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An experimental study has been made of the critical heat fiux (CHF) of natural convective boiling in vertical uniformly heated tubes. The experiment was performed at a pressure of P=0.1 to 3.1 MPa for the tube diameter of D-1.12 to 18.4 mm, the tube length of L=23 to 960 mm and three kinds of liquids. The effects of the pressure which corresponds to the density ratio pυ/pι ranging from 6.24×10^<-4> to 0.236 and of the ratio of L/D=5 to 857 on the CHF, are mainly discussed. The experiment shows that the characteristics of the CHF can be first divided into two regimes at a point where a nondimensional parameter of D/√<σ/g(pι-pυ)> is equal to about 13. In addition, the CHF in D/√<σ/g(pι-pυ)><13 can be further divided into two regimes ; the CHF of L/D < 240 takes place under the condition of slug or annular flows, and then the CHF data can be predicted with an accuracy of ±20% by Eq. (2), and the CHF of L/D=857 may be caused by flooding. On the contrary, the CHF in D/√<σ/g(pι-pυ)><13 occurs under the same conditions as the CHF in pool boiling. Then the CHF data are also correlated by Eq. (4), in which the tube diameter has no effect on the CHF.
一般社団法人日本機械学会の論文
1990-11-25