Experimental Study Of Subcooled Boiling On Heat Transfer Characteristics In Pulsating Flow

The use of nuclear energy is an inevitable trend of future energy development,but the safety of nuclear energy is always the key problem that limits people's energetically developing nuclear energy.Therefore,it is necessary to further study the reactor thermal hydraulics.Under the condition of ocean,the reactor is affected by the movement of swaying and undulating.How to ensure the safe operation of nuclear reactor under marine conditions is facing new challenges and difficulties.Natural circulation has a wide range of applications in the field of nuclear energy,but the related research is not very perfect.In this paper,experimental study on the heat transfer characteristics of natural circulation in the narrow rectangular channel,thermal experiments were carried out in vertical,inclined and rolling conditions respectively,the experimental data analysis,the research content mainly includes natural circulation thermal characteristics,onset of nucleate boiling of the research and subcooled boiling heat transfer characteristics.In the case of single-phase natural cycle heat transfer,the transition of the laminar and turbulent regions of the experimental section in the vertical state is 2250.Respectively laminar and turbulent Nu prediction are verified In the laminar flow region,Tian Sieder-Tate formula is well suited for this experiment.In the turbulent region,the prediction value of the Yang ruichang equation is small,and the prediction value of Gnielinski formula is a good formular of the test section of the experimental value.The influence of inclination on the heat transfer characteristics is mainly reflected in the laminar flow area.The positive inclination will increase the heat transfer coefficient of the laminar flow area,and the negative inclination has less influence on the heat transfer characteristics.The curves of the average Nu and the rolling angle of the channel with the time variation are given.The research of subcooled boiling in natural circulation is mainly divided into the study of onset of nucleate boiling and the study of the heat transfer characteristics of the supercooled boiling.The onset of nucleate boiling is visualized.The Su Shunyu formula can predict the heat flux at the onset of nucleate boiling well.The Yan formula can predict the subcooled boiling heat transfer coefficient,the error is less than 30%,the coefficient of heat transfer under high pressure is decreased;incline has great effect on the heat transfer characteristics of subcooled boiling.the positive inclination increases the heat transfer coefficient and the negative inclination decreases the heat transfer coefficient.;In the rolling condition,the thermal parameters with the time are given,and the average heat transfer coefficient and the rolling angle with time were shown.