Experimental validation of an analytical model for predicting the thermal and hydrodynamic capabilities of flat micro heat pipes

An analytical model by Lefèvre and Lallemand (1) that couples a 2D hydrodynamic model for both the liquid and the vapor phases inside a flat micro heat pipe (FMHP) and a 3D thermal model of heat conduction inside the FMHP wall has been modified. It consists of superposing two independent solutions in order to take into account the impact of evaporation or condensation on the equivalent thermal conductivity of the capillary structure. The temperature, pressure and velocity fields can be determined using Fourier solutions. The model has been experimentally validated based on literature data from a grooved FMHP. Two new correlations for the equivalent thermal conductivities during evaporation and condensation inside rectangular micro-grooves have been proposed based on a numerical database. The influence of the saturation temperature and geometry on the maximum heat flux transferred by the system is presented.