| It is significant for the fast breeding reactor steam generator(FBR SG) to study its thermal hydraulic mechanism, which it can operate safely and reliably. On the basis of the thermal-hydraulic theory of CEFR SG, the steady-state mathematical model of SG was established with the semi-analytical method in the paper. The boiling heat transfer mechanism of FBR SG was analyzed deeply. The thermal-hydraulic program of SG was developed with the help of steady-state heat transfer characteristics of SG. Further more, the influence of different structural parameters on the performance of the steam generator was discussed. After optimizing the structural parameters, the best structure of tube bundle was achieved. At last, the method of numerical simulation was used to simulate two different kinds of support plate. The conclusion obtained can guide the engineering application. The main works and results in this paper are listed as follows:(1) Comparison and analysis of thermal hydraulic calculation formula of CEFR SG under the condition of high pressure and high heat flux. The boiling region of fluid was divided in a reasonable manner in tube side. The results show that it is reasonable for the division with the departure from nucleate boiling quality(DNB)(2) The steady-state mathematical model of CEFR SG was established with the semi-analytical method. The mechanism of boiling heat transfer was discussed. The researches show that heat transfer mechanism between nucleate boiling region and film boiling region is different. At the same time, in the nucleate boiling region and other heat transfer regions, the main factor influencing the boiling heat transfer is different.(3) The steady-state heat transfer of CEFR SG was analyzed. The effect of load in secondary side, inlet water temperature and the flow of liquid sodium on heat transfer of SG was researched. The results show that with the reduction of load in secondary side, the boiling length decreases gradually. And the contribution of boiling reduces. When inlet water temperature rises up, the total quantity of heat which is transferred from liquid sodium to working medium in second side will reduce. The flow of liquid sodium has obvious effect on outlet temperature of the water vapor and length scale arrangements in every heat transfer region. Outlet temperature of the water vapor can be controlled by the flow of liquid sodium. (4) Sodium-heated steam generator was thermal-hydraulic designed. The influence of the tube length, outer diameter, wall thickness and tube spacing on the SG performance was discussed. JF factor was used to evaluate the comprehensive performance of the steam generator. On the basis of it, SN was used to determine the contribution ratio of each control factor. Comparison with JF factor, the effect each control factor on the performance of the steam generator is relatively independent. The optimal structure of tube bundle was obtained. Considering the construction cost, CER was used to evaluate the overall performance of the steam generator. It is not completely consistent between the optimal structure and the structure obtained above. The main difference is how to choose the tube length.(5) The large commercial software FLUENT is adopted to simulate the support structure of both circular hole and plum blossom hole. Comparison of velocity profile and temperature profile of working medium in both tube side and shell side was made. What’s more, this paper discussed its influence on heat transfer and pressure drop of the steam generator. The conclusion is that it is optimal for overall performance of the support structure of circular hole. |
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