Wall thermal conductivity effect on the heat transfer in circular pipe turbulent gas flow

The effect of the ratios fof thermal conductivity coefficients of pipe wall and gas (in the 0.01-8000 range) on the convectiVe heat exchange of a turbulent gas flow has been investigated. The problem is solved using the method of finite-differential approximation, with account of longitudinal heat flow both in the wall and in gas for the numbers Pr=0.7, Re=104-106, relative wall thickness of the channel, Δ=10-3-3. The calculation of temperature field, average mass flow temperature, temperature gradients at the gas-solid body boundary is made, using the FORTRAN-program for the ES-1060 computer. It is established that at the expense of axial thermal conductivity in a wall and liquid a considerable amount of heat can be transferred to the upper non-heated portion of the pipe. With the increase in the relative thickness of the channel wall and relative thermal conductivity the temperature jump distribution zone on the internal surface of the channel is expanded. Local values of the Nusselt numbers are given