A SEMIQUANTITATIVE THEORY OF CONVECTIVE HEAT-TRANSFER IN A HEAT-GENERATING FLUID

A semiquantitative theory of heat transfer in a heat-generating fluid within a closed volume is developed. The analysis is based on relation ships derived from the condition of energy balance and on modern physi cal concepts of heat transfer processes in an energy-neutral fluid. Fo ur main regimes and one asymptotic regime of heat transfer are singled out, which differ in the exponents of power in the expression relatin g the Nusselt number, Nu, and the modified Rayleigh number, Ra-I. In t he asymptotic limit, with Ra-I(-1/32) much greater than 1, heat transf er to the upper horizontal part of the boundary and the curved part of the boundary facing downward obeys dependences Nu(up) similar to Ra-I (7/32) and Nu(dn) similar to Ra-I(1/4), respectively. In the range of values of Ra-I which is of interest with regard to the safety problem of the nuclear power engineering the established theoretical correlati ons are in good agreement with the experimental data. (C) 1998 Elsevie r Science Ltd.