A computational model for the transient analysis of flat heat pipes

A computational model is developed for the analysis of the transient operation of a flat heat pipe. The analysis involves the solution of the two-dimensional continuity, momentum and energy equations coupled with the state equation in the vapor core, the transport equations for a porous medium in the wick, and the two-dimensional heat conduction equation in the heat pipe wall. The equations are discretized and solved using a finite-difference approach. Variations in the temperature, pressure and velocity fields are obtained as a function of time. The effect of the axial conduction through the heat pipe wall and wick, which causes heat to flow into the interior in the externally adiabatic section, thus affecting the velocity distributions in the wick and vapor, is brought out in the present analysis. The heat removal capability of the heat pipe is contrasted to that of a solid copper block of the same overall dimensions as the heat pipe, and a copper plate with dimensions equivalent to those of the heat pipe wall.