Numerical study of transient heat transfer performance for molten salt receiver tube

The heat transfer experimental system and mathematical model of receiver tube are established to analyze the transient heat transfer performance of molten salt with heat flux of outer wall sudden change, molten salt velocity sharp reduction, heat flux of outer wall and molten salt velocity sharp reduction at the same time. The results show that when the heat flow on the outer wall of the tube changes suddenly (sudden increase or decrease), the temperature of the molten salt in the center of the tube at the inlet section of the heat absorption tube changes less, but the temperature of the tube wall changes faster. When the molten salt velocity sharp reduction, the outlet temperature of molten salt and the outer wall temperature increase with time, but the difference of outer wall and inner wall temperature decreases at first and then increases, when t≥16.0 s, each temperature and temperature difference reach steady state. When the heat flux on the outer wall of the heat absorption tube and the molten salt flow rate in the tube are halved at the same time, the temperature of the molten salt in the center and the outlet of the tube rises first and then decreases with the passage of time. After the steady state, the two molten salt temperatures maintain a constant value and are compared with the transient state. The corresponding molten salt temperature is close to initial starting temperature. The difference of outer wall and inner wall temperature after transient stability is proportional to the heat flux of outer wall, but which is independent of molten salt velocity. The outlet temperature equation of molten salt in receiver tube after transient stability is obtained, which provides a theoretical basis for the outlet temperature control of molten salt in receiver during the transient heat transfer process.