Heat Transfer Analysis And Regression Evaluation Of Fluids At Supercritical Pressures In Vertical Upward Ducts

As the only type of water-cooled reactor among the six advanced nuclear energy systems proposed by the Generation-IV International Forum, Supercritical Water-Cooled Reactor (SCWR) has the prominent advantages of high thermal efficiency, system similicity, small size and competitive economy. Since PWR is the target for short and mid term development in China, research and development of SCWR comes into an essential choice under the present circumstance of energy structure and practical requirement, considering the technical continuity and request of sustainable development. Among the fundamental topics and nessesary basis of SCWR R & D, study on heat transfer characteristics of fluids at supercritical pressures has received great attention.In this thesis, available experimental data of forced convective heat transfer of water, carbon dioxide and Freon in vertical upward ducts at supercritical pressure are extensively collected, categorized and analyzed. Investigation and discussion on the mechanism of forced convective heat transfer in ducts of supercritical fluids, and the effects of various factors on supercritical heat transfer, such as abrupt change of fluid thermal-physical properties near the pseudo-critical region, action of buoyancy and acceleration caused by the decease of fluid density from heating, etc. are conducted in detail. Based on the study, dimensionless numbers representing impact of buoyancy and thermal acceleration are therefore introduced, while the modification terms of the ratios of fluid thermal-physical properties at wall temperature and at bulk temperature are dealed with to extract main information, applying principal factor analysis. Furthermore, experimental data of water forced convective heat transfer in vertical upward ducts at supercritical pressures are regressively correlated. By comparing the prediction results with the experimental data under certain conditions, error and accuracy analysis for the correlation arrived is presented. Finally, according to the modeling criterion of corresponding state similarity, the author attempts to correlate a general heat transfer correlation for multi-fluids, along with a preliminary evaluation.With the work of this thesis, a preliminary experimental database of forced convective heat transfer of different fluids in vertical upward ducts at supercritical pressures, as well as research framework of data categorization, analysis and correlation, is constructed, which might lay a foundation for further comprehensive and intensive analysis and exploration of the features of forced convective heat transfer for different fluids at supercritical pressures.