K-1832 Natural-convective heat transfer in a uniformelyheated pipe annulus : Effect of Prandtl number

Abstract

Natural convection in .a vertical councentric pipe annulus is investigated numerically for laminar flows at the modified Grashof numbers Gr^*=10^2〜10^5. In numerical calculations the thermal entrance region for Prandtl numbers of 0.01,7.0,50 is examined at the diameter ratios d _i/d_0=0.2,0.5,0.8. From the results obtained acorrelation equation is presented for thermal entrance length x/b.