CHF enhancement in flow boiling system with TSP and boric acid solutions under atmospheric pressure

Abstract

In several studies, it was demonstrated that surfactant affects the heat transfer with the change of fluid property related with bubble formation and behavior due to the decrease of surface tension. G. Hetsroni et al. [1] showed in their experiments with Habon G surfactant that the heat transfer of the boiling process is enhanced considerably by the addition of a small amount of surfactant. It was also experimented by Rozenblit et al. [2] on how flow changes in surfactant solution. It showed that gas bubbles in air-water solution with surfactant are smaller in size but much larger in number than in pure air-water mixture, at all flow regimes. In recent, an experiment was performed by Jeong et al. [4], which was on flow boiling CHF enhancement with TSP surfactant solutions under atmospheric pressure in SS316 circular tube. It was represented that the addition of TSP surfactant helps to increase wettability by reducing surface tension and the increment is vary with the concentration of TSP, mass flux, and subcooling. Tri-sodium phosphate (TSP, Na3PO4·12H2O) and boric acid (H3BO3) are used in nuclear power plant for maintaining high pH level during accidents. It is noticed that boric acid concentration is about 2000 ppm at normal condition and about 4000 ppm in IRWST. In this study, the variation of the CHF is observed in water with TSP or boric acid at circular tube of flow boiling water system under atmospheric pressure. Same procedure of the experiment is performed on several concentrations of TSP or boric acid, and it was shown that TSP and boric acid are effective for the CHF enhancement from the results of the experiment.