Study On Flow And Heat Transfer Characteristics In A Straight Semi-Circular Channel Of Plate Once-Through Steam Generator

The Plate OTSG(Once-Through Steam Generator)has an important application prospect in the pre-research of miniaturization and modularization of PWR(Pressurized Water Reactor)because its volume power ratio is 100 times higher than the traditional shell and tube steam generator.In this paper,aiming at the flow and heat transfer characteristics in the typical long straight semi-circular channel of the Plate OTSG,the experiment and numerical simulation of single-phase flow and two-phase flow are carried out in order to provide support for the thermal and hydraulic design of OTSG.In the aspect of experimental research,the flow and heat transfer experiment section of a long straight semi-circular channel with diameter of 3 mm is designed and processed,and the corresponding flow and heat transfer experiment system platform is established.After the debugging and calibration of the experimental system,the thermal and hydraulic experiments of single-phase flow and phase change heat transfer two-phase flow in the semi-circular channel are carried out.The single-phase flow experiment studies the single-phase fluid thermal hydraulic characteristics of the primary side circulating water in the Plate OTSG.The predicted values of the Nu and f correlation of the equivalent circular tube are compared with experiment results,and the correlation of Nu and f of the straight semi-circular channel is obtained through the correction of the experimental results.The phase change heat transfer two-phase flow experiment investigates the heat transfer characteristics of the two-phase fluid flow in the secondary side circulating water in the Plate OTSG.The effects of fluid pressure,mass flow rate,heat flux and thermodynamic equilibrium quality on the heat transfer coefficient and pressure drop in a semi-circular tube are studied experimentally.The results show that the fluid heat transfer coefficient and pressure drop in the semi-circular tube have different variations trend at atmospheric pressure and higher pressure.In the aspect of numerical simulation research,three kinds of CFD analysis models are established.The first one is the long straight semi-circular channel flow-solid coupling analysis model that is the same as the experimental model.Based on this model,the numerical model analysis of single-phase flow and two-phase flow with phase change in the tube is carried out under the condition of bottom heating;the second is to take a pair of typical channel units of the Plate OTSG to establish a fluid solid coupling analysis model,and carry out numerical simulation analysis of flow and heat transfer characteristics in pipes under actual heating conditions;the third type is to take 5 pairs of typical channel units to establish the fluid-solid coupling analysis model,and conduct numerical simulation research of flow instability.The results of numerical simulation show that the ?-? turbulence model is more suitable for the simulation of single-phase convective heat transfer in the straight semi-circular channel;the homogeneous flow model combined with the corrected rohsenow model can well predict the flow boiling heat transfer characteristics in the straight semi-circular channel,and the relative deviation between the simulation value and the experimental value is-30% ? 40%;simulation results of the second kind of CFD model can better clarify the flow and heat transfer characteristics of the actual steam generator tube;simulation results of the third kind of CFD model can provide reference for the overall layout design of the internal heat transfer channel and the structure design of the inlet and outlet section of the steam generator.