CONVECTION AND RADIATION HEAT TRANSFER IN A PASSIVE CONTAINMENT COOLING SYSTEM

摘要

One essential feature of the composite containment is itsrnpotential to remove the decay heat by natural air convectionrncoupled with thermal radiation. Experimental investigationsrnhave been performed to determine the coolability of such arnpassive cooling system and to study the contribution of thermalrnradiation to the decay heat removal. By these experimentsrndifferent effects, e.g. the effect of the heated wall temperturernand the wall emissivity, on heat transfer are studied. A data basernhas been provided for validating advanced multi-dimensionalrncomputer codes and for developing physical models. Inrnaddition, numerical calculations have been performed by usingrnthe three-dimensional computer code FLUTAN to simulate flowrnconditions and heat transfer behaviour in an one-sided heatedrnrectangular flow channel. From the results achieved so far it hasrnbeen found that the passive containment cooling by natural airrnconvection coupled with thermal radiation is a promisingrnconcept. Both the experimental data and the numerical resultsrnshow that for intermediate and high wall emissivities,rnrespectively, thermal radiation enhances significantly the entirernheat transfer, even at low temperatures of the containment wall.rnThe FLUTAN code combined with the radiation modelrndeveloped has been proven to be an accurate and efficientrnnumerical tool for investigating flow and heat transferrnbehaviour in the system considered.