Restriction of Critical Heat Flux by Critical Flow Condition in Capillary Tube

Critical heat flux (CHF) is a very important design factor of boiling channel, then, so many investigations have been conducted so far. In the case of small diameter channel, the main interest is related with the heat removal of high heat flux component. Therefore, CHF of that system should be predicted by DNB condition. On the other hand, CHF under low heat flux condition in small channel can be considered as the relation with two kinds of restrictions. In this investigation, the confirmation of the relationship of two restrictions in CHF was principal purpose. The CHF of this system was basically decided by the dryout condition, but it deviated from the dryout under certain conditions. In those conditions, the critical flow condition achieved in lower heat flux compared with that of the dryout. Owing to this restriction of the flow rate by critical flow condition, pseudo CHF condition occurs. Experimental results have expressed these relationships between CHF and critical flow condition well.