On Free Transient Convective Heat Transfer Between Cable and its Surrounding Pipe or Duct Wall

The transient free convection heat transfer problem between cable and its enclosure is solved using the method of finite difference. As the transient time is found to be very small compared with a typical operation time, the steady state Nusselt number Can be used in lieu of the transient Nusselt number. Our numerical results are summarized in Fig. 9 which consists of three Nusselt number vs. Grashof number plots with diameter ratio as parameter and serves as a design chart for practical free convective heat transfer calculations.