Critical heat flux analysis of divertor cooling flow channel in fusion reactor with CFD method

Abstract

Situated at the bottom of the vacuum vessel, the divertor extracts heat and ash produced by the fusion reaction, minimizes plasma contamination, and protects the surrounding walls from thermal and neutronic loads. The vertical targets of divertor are designed to be able for up to 20 MW/m2 high heat flux. It is a great ordeal for both the material performance and the cooling ability. Critical heat flux (CHF) margin is very crucial during the design of divertor. ANSYS FLUENT is used in this paper to predict the CHF on a monoblock structure with a twisted tape inside the tube. Numerical results are validated with the corresponding sets of experimental results. In this paper, CFD method used to predict CHF of divertor cooling channel was first introduced. On the other hand, influence of inlet subcooling on CHF is studied in detail. The inlet subcooling affect the CHF much complicated for the single- side heated and swirl flow channel. Whether the influencing trend or the locations of CHF occurrence are different under different inlet subcooling. The derivations between the simulation and experimental results were no more than 32%. This study proves the CFD tools can provide efficient help on the understanding of the CHF phenomenon of complex construction.

Onset of flow instability with one-side heated swirl tube for fusion reactor safety

“…Wang et al [16] q OFI = 0.9( P h Pw )q sat 87.75 106.01 R = T out −T in T sat −T in = 0.9( P h Pw ) Al-Yahia & Jo [18] q OFI = 0.8q sat ( P h Pw )( p 1.12 ) 0.4 112.89 157.19…”

“…In a recent study, there is a case of evaluating the CHF of a swirl tube by simulating the fusion cooling system conditions through computational simulation method. Li et al [16] calculated the CHF of a one-side high heat loaded swirl tube under the conditions of a pressure of 30 bar, a flow rate of 0.7-2.8 m 3 h −1 , and sub-cooling of 36 • C-144 • C using computational fluid dynamic (CFD). It is noteworthy that the calculation result was derived that sub-cooling and CHF do not have a linear proportional correlation.…”

“…The cooling system of the commercial power plant is highly likely to be operated under a lower subcooling condition than that of the ITER cooling system for the economic efficiency of the power plant. However, if an unexpected high heat flux is loaded on the PFC under the subcooling condition lower than 72 • C, it can generate a large amount of vapor inside the channel [16]. The generated vapor can rapidly fluctuate the system pressure, and if density oscillation is induced due to fluctuating pressure, the flow rate is suddenly lowered instantaneously, this causes local dry-out at the flow path wall.…”

Experimental study of thermal limits with one-side heated smooth channel for plasma facing component safety

“…; p = liquid specific heat (J kg −1 • K); P h = heated perimeter (m); P w =wetted perimeter (m); A=heating area [mm 2 ] (3) re-learn the model using all the normal values; (4) calculate the error between the learned model and the normal value (the error is calculated using the median absolute deviation (MAD); and (5) repeat the algorithm until it reaches a user-specified convergence value. The performance of this model was evaluated using a determinant (R 2 ), where R 2 is a measure of how well the estimated model fits all the data, and it can be obtained by (14). R 2 has a value ranging between 0 and 1, indicating that the model has learned.…”

“…where In recent studies, many studies have been conducted to evaluate the critical heat flux safety margin under oneside high heat load conditions inside the tokamak. Xiangyu Li et al [14] evaluated the CHF of mono-block plasma facing component with twisted tape inserted through computational fluid dynamics (CFD) simulation and compared it with experimental values. As a result, the experimental and calculated values showed an error rate of up to 32%, and this results showed that CHF could be accurately predicted through CFD simulation even under high-pressure, high-velocity, and high-temperature fluid conditions.…”