Feasibility study for R123 flow boiling under pressurized conditions

Abstract

Many thermo-hydraulic experiments aim to depict high temperature and pressure conditions of nuclear po wer plant (NPP). However, it is hard to conduct experiment on operating conditions of NPPs with water, w hich is reactor coolant of LWRs. Thus, refrigerants are frequently used as scaling fluid since they have mu ch lower boiling point and latent heat of evaporation compared to water. Operation conditions of NPPs suc h as pressure and mass flux are converted to refrigerant’s experimental condition utilizing dimensionless p arameters. With this method, critical heat flux (CHF) of water at desired condition could be modeled with refrigerant experiment. Recently, CHF studies under pool boiling suggests possible enhancement mechani sms that could be applied to various heater surfaces. Applicability of CHF enhancement methodologies in real engineering facilities became main issue. Thus, 2,2-dichloro-1,1,1-trifluoroethane (R123) flow boilin g loop is designed for CHF measurement under pressurized conditions. In this paper, preliminary CHF exp eriment with R123 is discussed. Experimental conditions are vertical upward flow with SS316L tube as te st section. Plausibility of R123 analogy is discussed based on the accuracy of experimental CHF data by c omparing with water’s equivalent CHF from 2006 look-up table. Moderate prediction accuracy of deviatio n with 3.48 to 11.4 % were achieved while test condition with low mass flux had higher deviation.