Numerical prediction of flow and mixing characteristics in CVCS chemical addition system

A numerical result of the flow and mixing characteristics is presented for the flow field created by water injected into a cylindrical tank with an in itially stationary fluid. The flow is relevant to the operation of the chem ical addition system in the chemical and volume control system (CVCS) of nu clear power plants. This study was undertaken to provide a basis for modifi cation of the previous design which gave a number of difficulties in instal lation and operation of the chemical addition system because it needs a spe cial reciprocating pump with a high actual head. For the tank of length-to- diameter ratios (L/D) of 1, 2 and 3, each with and without a baffle inside, calculation results were obtained by solving the unsteady laminar two-dime nsional elliptic forms of governing equations for the mass, momentum and sp ecies concentration. Finite-difference method was used to obtain discretiza tion equations, and the SIMPLER solution algorithm was employed for the cal culation procedure. Results showed that the baffle was very effective in en hancing the mixing in the tank, and that a baffle should be installed near the tank entrance in order to inject chemicals into the reactor coolant sys tem (RCS) within the operating time required. (C) 1999 Elsevier Science S.A . All rights reserved.