Thermal-hydraulic analysis of once-through steam generator with annular narrow slot tube

Integrated small modular reactors (SMR) have garnered significant attention in the field of nuclear energy, with the high-performance integrated steam generator being a critical technology for their advancement. The highperformance once-through steam generator (HP-OTSG) featuring an annular narrow slot tube, which leverages narrow channel enhanced heat transfer technology, holds significant potential for future applications. However, research on the design and experimental studies related to this type of steam generator remains significantly limited. This paper establishes a thermo-hydraulic analysis method for the OTSG based on the segmented heat exchanger design ideas, and the analysis method is verified by comparing the calculation results with those in the literatures. Then, the experimental studies conducted in the annular narrow slot tube and the related conclusions are comprehensively reviewed and subjected to an accurate assessment. The design parameters of a typical SMR, 200 MW Nuclear Heating Reactor-II (NHR200-II), are selected to evaluate and analyze the accuracy and validity of the correlation based on the annular narrow slot tube in the different heat transfer regions including the onset of nucleate boiling (ONB) point, saturated boiling heat transfer coefficient (hsat), dryout point, and the post-dryout heat transfer coefficient (hpdo). Finally, the influences of operational and geometrical parameters on the performance of the HP-OTSG are analyzed, and the design optimization of the HPOTSG is performed according to several performance indicators including Power Density (PD), Area Density (AD), pressure drop (Delta p), secondary steam temperature (T2out), heat transfer factor (j), the proportion of nucleate boiling zone length in H (PNL), the point of dry-out (Xdryout), and the length of heat exchange tube (L). The model developed in this paper extends the application range of high-performance steam generators to annular narrow slot tubes. The calculation model including both of the analysis method and the heat transfer correlations established in the present study can serve as a useful tool for the design and optimization of HP-OTSG, which further prompts the development of integrated SMR with built-in steam generator.