Natural convection of heat generating fluid within horizontal cylinder

In the fluid accompanied by nuclear fission reaction and radioactive decay, the natural convection occuring through internal heat generation, exerts large influence on the temperature distribution in the fluid and the thermal load distribution on a demarcation wall. Accordingly, for the safety design of tanks storing liquid nuclear fuel or radioactive waste solution it is important to accurately grasp the heat transfer characteristics of this natural convection. In this research, a horizontal circular pipe was taken up, and the examination of natural convection heat transfer was carried out. This system becomes practically important when the rate of heat generation of fluid is large, such as a dump tank for emergency use in a molten salt nuclear reactor. In this research, the Navier-Stokes equation and an energy equation were numerically analyzed by difference calculus, and temperature distribution and velocity distribution were theoretically determined in the range of Rayleigh number of 108, and the effect of various factors on the heat transfer was clarified. The rate of heat transfer was measured by electrically heating dilute NaCl solution, and compared with the theoretical results. (Kako, I.)