管内強制流動沸騰系の上流限界熱流束

抄録

Critical heat flux (CHF) of a uniformly heated tube usually occurs at the tube exit but is sometimes detected at an upstream location under high mass flux at high system pressure. To clarify the characteristics of upstream CHF, systematic experiments were conducted using R115 as the test fluid over wide experimental ranges of system pressure, mass flux, tube length and liquid inlet subcooling. As the inner surface roughness of the test tube was found to have a strong influence on the CHF, three test tubes with different inner surface finishes were used. From the experiments, the followings results are obtained : (1) upstream CHF is an autonomous phenomenon ; (2) up-stream CHF is likely to take place in a rough tube ; (3) upstream CHF is more likely to take place at low inlet subcooling and high pressure under high mass flux ; (4) upstream CHF is greater than usual downstream CHF for the same inlet subcooling ; (5) downstream CHF can be correlated uniquely as a function of local quality whereas upstream CHF data deviate from the unique relation.