Thermal-hydraulic Characteristics Analysis Method of Helical Coil Steam Generator in High Temperature Gas Reactor

Abstract

High temperature gas reactors (HTGRs) have broad application prospects in power supply, seawater desalination and hydrogen production. Helical coil steam generators have the advantages of compact structure, high heat transfer efficiency and resistance to expansion thermal stress, which was widely used in energy supply, power engineering, petrochemical and other fields. The steam generator of HTGRs has complex structure and severe operating conditions. It is very important to accurately predict its thermalhydraulic characteristics under normal operation and typical transient conditions for the safety of HTGR. Based on this, a general and accurate heat transfer model was established by using homogeneous flow model, the system thermalhydraulic analysis code for high temperature gas reactor helical coil oncethrough steam generator (STAGS) was developed. Based on THTR300 reactor steam generator, the outlet temperatures of tube and shell side predicted by the system code were compared with the experimental data, and the calculation error of both sides is less than 3 K. It is proved that the system code can effectively predict the thermalhydraulic characteristics of helical coil steam generator in HTGRs under normal operation conditions. Taking high temperature gas cooled pebblebed module (HTRPM) reactor as the research object, the characteristics of the helical coil steam generator under full power condition were analyzed, and the distribution of key thermalhydraulic parameters along the helical tube was obtained. The results show that the thermal resistance of the tube side increases sharply after entering the liquiddeficient area, and the thermal resistance of the shell side is greater than the thermal resistance of the tube side and the tube wall at different positions of the heat exchange tube bundles, which has a major impact on the heat transfer. A study was carried out on the influence of the fluid mass flow at the shell and tube sides on the operating characteristics of HTRPM steam generator. The results show that the maximum value of the heat transfer coefficient at the tube side is greatly affected by the tube side fluid mass flow. Then the response of the key parameters of the steam generator when the thermalhydraulic parameters of two sides inlet was disturbed was studied. The results show that the change of the thermalhydraulic parameters of the shellside helium has a severe impact on the heat transfer power of the steam generator. When the shell side helium mass flow drops by 10% and the inlet temperature increases by 20 K, the heat transfer power of steam generator decreases by 968 kW and increases by 664 kW respectively. This work has reference significance for design and safety analysis of helical coil steam generator in high temperature gas reactors.

Keywords

• high temperature gas reactor
• helical coil steam generator
• thermal-hydraulic analysis
• system code