Investigation of the heat exchanger bundle effect for the passive condensate cooling tank using the CUPID code

The need for a multi dimensional analysis of transient thermal hydraulic phenomena in a component of a nuclear reactor is increasing with the advanced design features. Motivated by this, the development of a new thermal hydraulic analysis code, named CUPID, is in progress at KAERI (Korea Atomic Energy Research Institute). The simulation of the passive secondary cooling system, PAFS (Passive Auxiliary Feedwater System) has been considered as one of the practical applications of CUPID. In order to validate the two phase flow models of CUPID, the PASCAL test facility was simulated with a porous media model in our previous study. In the present study, the heat exchanger bundle effect on the natural circulation heat transfer was investigated using CUPID for the passive condensate cooling tank (PCCT) of the PAFS. The calculation results with the porous media model, such as the liquid temperature and velocity, were imposed as boundary conditions of the detailed flow simulation near the single heat exchanger tube of the PASCAL facility. Thereafter, the bundle effect was investigated by comparing the calculation result of the unit cell of the PAFS tube bundle and that of the single tube. This paper presents the two dimensional porous media analysis result for the PCCT of the PASCAL facility, two dimensional open media analysis result for a single heat exchanger tube, and two dimensional open media analysis result for the unit cell of the heat exchanger bundle