A New Approach for Thermo-Fluid Behavior through Porous Layer of Heat Pipes

Abstract

This paper developed a new mathematical model to investigate the heat transfer as well as wick thickness of a heat pipe. The model was set up by conservative equations of continuity, momentum and energy in the thermal boundary layer. Using the similarity variable, the governing equations have been changed to a set of ordinary differential equations and they were solved numerically by the forth order Runge-Kutta method. The flow variables such as velocity components, wick thickness and Nusselt number were obtained. The results show that the Nusselt number is proportional to the root square root of the Darcymodified Rayleigh number and that the distance from the edge of the condenser surface. Furthermore, the thickness of the wick material depends on the Jakob number and proportional to the heat transfer between the wall and the liquid film.

Assessment of Vapor Formation Rate and Phase Shift between Pressure Gradient and Liquid Velocity in Flat Mini Heat Pipes as a Function of Internal Structure

“…The fluid moves through the capillary layer and starts to wet the inner porous cavities of the porous medium, creating a convective-type phenomenon. In this case, for porous media, the Nusselt number can be determined as a function of Reynolds number and/or Prandtl number by empirical relations proposed by various authors in different forms [ 13 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ], at which the flow regime is turbulent. …”

“…In the graph shown in Figure 4, the correlation between the Nusselt number and porosity was represented when the Prandtl number changes for convective transfer between the two capillary media. It should be noted that Petukhov [25] indicates values of the Prandtl number for a fully developed turbulent pipe flow ranging from 0.5 to 2000 while the Nusselt equation deduced by Gnielinski [22,[26][27][28] for turbulent as well as transition regions for a smooth tube is valid only if 0.6 < Pr < 10. The amount of liquid carried through the two media (copper microsphere surface and trapezoidal microchannels) is not the same.…”