Application of a Taylor's Series Approximation to Represent the Heat Transfer Constitutive Relationships in Thermal-Hydraulic Computer Codes

摘要

A technique for decreasing the computer execution time for convective heat transfer calculations in thermal-hydraulic computer codes is investigated. The technique consists of approximating the convective heat flux by the first-order terms of a Taylor series expansion, with fluid and heat structure conditions as independent variables. The approximation is used until the system state point varies enough to make the approximation inaccurate. The technique was incorporated into the RELAP5 computer code. Calculations were performed to determine the savings in computer-execution time and to verify the accuracy of the approximation. In slowly varying transients, the approximation ran up to 16.5% faster than the current calculation technique in RELAP5. In rapidly varying transients, it ran slower than the current technique. (ERA citation 08:014920)