Experimental Investigation of Heat Transfer and Burnout in Condition of Nonuniform Megawatt Heat Fluxes

Abstract

Bunwut is investigated in tubes under nonuniform heating on the perimeter. Data on heat trrmsfer and crilical heat flux ('IchtJ in the case of water were obWilled for ranges of mass ve/Dcily pw -200-3000 kglm 2 s, pressure p -0.1-1 MPa, and inlet water temperature T -2S-9SoC. The test section was a horivmtal copper tube of 21 mm outer diameter, S mm inner diameter with a technwally smooth surface and heat transfer-intensifying twisted tape and porous sintered coating. The test section was hented by bombardment with electrons. It is es/abUshed that a redistribution of heat fluxes and an increase of wall temperature fluctuations occur at burnout. The range of regime parameters to prevent burnout of a heat transfer surface is detennined.

Investigation of hydraulic drag and heat transfer in a single-phase swirl flow under one-sided heating

“…In the activities within the ITER program [5,6], primary attention was given to the investigation of critical heat loads, and much less attention was given to singlephase convection. Schlosser and Boscary [5] suggested using the Dittus-Belter relation for the calculation of heat transfer under conditions of single-phase convection, which serves as an indirect proof of the results of Komendantov et al [3] who used the wellknown relations for flows in straight pipes for generalizing the heat transfer in the mode of single-phase convection.…”

“…A distinguishing feature of the latter devices consists in one-sided heating of heat-absorbing surfaces and strong subcooling of heat-transfer agent. The heat transfer and boiling crisis in a subcooled swirl flow of water under conditions of one-sided heating were experimentally investigated in 1990s in application to the problem of cooling particle beam detectors in a number of laboratories both in Russia [3,4] and in other countries [5,6]. The basic diagrams of facilities and the procedures for investigation and processing of primary data turned out to be fairly similar, in spite of the fact that the investigations were independent.…”

“…The wall temperature and the distribution of heat flux density over the inner perimeter were calculated by solving numerically the boundary-value problem of thermal conductivity in the working section. Both the direct [4,5] (in this case, the calculation formulas for the heat-transfer coefficients and the relations defining the boundaries of the modes were varied) and inverse problems of thermal conductivity [3,6] were solved. In both cases, agreement between the predicted and measured temperature fields in the working section served as the criterion of reliability of solution.…”