The Gas-Liquid Two Phase Flow And Heat Transfer In The Pool With Internal Heat Sources

Two-phase flow and heat transfer is widely existed in the fields such as power engineering, medical and chemical engineering, metallurgy , cooling of electron devices as well as reactors engineering and etc. In the medical isotope reactor (MIPR) to separate and purify the medical isotope 99Mo and 131I, the reactive heat is constantly generated in the process of reaction, associated with the production of fission gas. In order to control the average temperature (usually≤80℃) of the reactor to prevent the sample from volatilizing, the cooling system of the reactor need to be designed carefully, i.e., the tube bunds of exchanger, the inlet temperature and flow rate of the coolant must be appropriately selected. In the reactor, the cooling process is a complicated process, not only because of the natural convection which is caused by the temperature difference with the volume heat source, but also the bubble drived flow by the fission gas. At the present, the domestic and foreign studies on the liquid-gas two phase flow were mainly focused on mixed convection in the tubes, while there is little literature about natural convection with internal heat source and cooled by the cooling coil in the pool, especially the literature about two-phase convection heat transfer drived by air bubble.In the dissertation, the three-dimensional physical and mathematical model of heat transfer of natural convection in the pool conjugated with forced convection in the tube were firstly established, and were numerically solved; Then physical and mathematical model of the gas-liquid two phase flow which was actuated by the bubble in the pool, were proposed and solved numerically.The effects of velocity of cooling water in the coiled tube and the internal heat source of the pool on the natural convection heat transfer performance in the pool and the total heat transfer performance were investigated. Furthermore, the effect of air bubble on the heat transfer performance was studied. The computed results showed that:(1) Without the drive of air bubble, the total heat transfer coefficient relational curve was obtained under different flux of the cooling water in the coiled tube and the volume heat source intensity in the pool, the results are approximately consistent with the experimental ones.(2) The numerical calculating discovered that the volume heat source intensity has...