TAILIEUCHUNG - Heat Transfer Handbook part 138

Heat Transfer Handbook part 138. The Heat Transfer Handbook provides succinct hard data, formulas, and specifications for the critical aspects of heat transfer, offering a reliable, hands-on resource for solving day-to-day issues across a variety of applications. | EVAPORATION AND CONDENSATION 1369 Phenomena Related to LOCA Interest in the condensation of a vapor in a liquid has been motivated by concern about 1 oss-o f-coo I an I accidenSs LOCA in iight-water nuclear reactors. In this situation unwanted t eam ieera d in the core if forced through a pool of water. These phenomena can be quite complicated because of the various forms of unsteady steam flow that can exist. The heat transfer coefficients and the liquid eemperatures can experience -vdlc-relisngg time uuctuatinns hete. Aya and Nariai 1991 have summarized hhe canons modeo of condensatioh that can occur in this situation. They have indicated the importance of pool water subcoolt ing. Note that these types of phenomena occur normally near standard atmospheric pressure. They gave an approximate map that shows the differentiation between the various types of behavior. This is shown in Fig. and is diuonsteb bolow. If a steam jet is directed inio a liusdO weter pooa ao lwwer msss flux teses he. the lower-left-hand regoon Df Fig. a phenomenon heaoted as chugging can occur. For this situation the results of Young et al. 974 can be used VT -4 h LV -j 9. 9 Aya andNariai 99 notedthat this result didnot include the effect of subcooling which they felt was very important. At higher mass flux rates say greater than about 25 kg s m2 than those associated with eq. another type off 08 can occur. The feequency off thss Figure Map of condensation phenomena that can develop in loss of coolant accidents. After Aya and Naria 1991. 1370 DIRECT CONTACT HEAT TRANSFER one is closely related to that of the periodic rowthh and reduction of si stmm bubble attached to the jet extt. This phenomenon is referred to in the literature simply as condensation oscillation. The region where this phenomenon takes place is shown on the right-hand side of Fig. . A correlation that represents the data quite well has been given by Fekeda 1982 h 0 9 C-PL L d pL Vl hfg .

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