Critical heat fluxes in internally heated annular channels

The development of a mathematical expression to express critical heat fluxes in internally heated annular channels is described. The generalizing equation developed made use of Soviet and other data. The critical heat flux depends both on the operational parameters (pressure, mass velocity and relative enthalpy at the point of burnout) and the geometric characteristics of the channel (diameter of the heated rod, annulus size, and length of section). The limitations of applicability of the equation developed to ranges of these variables are given. Calculated and measured critical heat fluxes are compared. The deviation of more than 80% of all experimental data from the results of calculation by the equation did not exceed +-20%. This agreement should be recognized as quite satisfactory, especially when the great scatter of the experimental data themselves is considered. Thus, the approximating relation with adequate accuracy generalizes data published in world literature on the first kind of burnout in internally heated annular channels.