Studies on steam condensation with non-condensable gases in a horizontal condenser tube for advanced nuclear reactors using RELAP5

Abstract

Horizontal heat exchangers are used in advanced light water nuclear reactors in their passive cooling systems, such as Residual Heat Removal System (RHRS) and Passive Containment Cooling System (PCCS). Horizontal condensation studies of steam with non-condensable gases mixtures in these heat exchangers are very important. This work presents a comparison between simulation results and experimental data in steady state conditions for some inlet pressure, steam and non-condensable gases (air) inlet mass fractions. The test section was modelled and the simulations were performed with the RELAP5 code. Experimental tests were carried out for 200-400 kPa inlet pressure and 5%, 10%, 15% and 20% of inlet air mass fractions. Comparisons between experimental data and simulation results are presented for 200 kPa and 400 kPa pressure conditions and showed good agreement. New correlations for heat transfer coefficients in these steam-air conditions must be theoretically and experimentally studied and implemented in the RELAP5 code.

A review: passive system reliability analysis – accomplishments and unresolved issues

“…In an experimental validation of RELAP5, Hassan and Raja (1993) found that for condensation in presence of non-condensable in U-tube, there were large discrepancy in calculated primary temperatures for several cases and also the nitrogen contents in the tube. Macedo and Torres (2009) have shown that for horizontal condenser tubes of an advanced nuclear reactor, RELAP5 code overestimates heat transfer coefficients for the higher inlet air mass fraction and hence calculated temperatures were smaller than experimental data. Based on the comparison of results from experiments, Fahri (2010) has observed that RELAP5/Mod3.3 cannot evaluate the relationship between mixture Reynolds number and air accumulation at interface leading to under-predicted wall sub-cooling and over-predicted heat transfer coefficient with an unacceptable deviation.…”

Modelling of Passive Heat Removal Systems: A Review with Reference to the Framatome KERENA BWR Reactor: Part I

“…Their results showed a high discrepancy compared to data from experiments conducted at Purdue University. Macedo et al [69] performed experimental and numerical investigations on the effect of non-condensable gases during steam condensation in horizontal tubes for pressure values between 200 to 400 kPa. The comparison revealed an overestimation of the heat transfer for higher pressures.…”