CFD analysis on flow and heat transfer characteristic in natural circulation system with subchannels under rolling conditions

The combination of advancement in nuclear technology and ship engineering is a new technology of nuclear application which can not only marine capability and provide power for remote islands, but also help solve the practical issues of high cost, high pollution and high pressure in cutting down emissions in the petroleum exploitation field. The CFD analysis in this paper focuses on the exploration of single-phase natural circulation flow and heat transfer characteristics for rod bundle under rolling conditions. The rolling version CFD tool is developed and compared with the calculated results by system code. The natural circulation system which consists of a 2 by 2 subchannel is established. This paper mainly focuses on the effect of different rolling parameters on natural circulation flow and heat transfer characteristics for rod bundle loop under rolling motion. The thermal-hydraulic performance varies periodically under rolling motion. The variation period equals to rolling period. The stronger the rolling intensity is, the greater the fluctuations of different thermal-hydraulic parameters are. The average values of mass flux and heating section temperature difference under rolling conditions are lower than those under non-rolling conditions, proving that rolling motion may enhance heat transfer. Meanwhile, the inlet temperature of heating section under rolling conditions is lower compared with that under non-rolling conditions. With increasing rolling intensity, the effect of heat transfer enhancement is greater. (C) 2020 Elsevier Ltd. All rights reserved.