A ONE-DIMENSIONAL MODEL OF A MICRO-HEAT PIPE DURING STEADY-STATE OPERATION

Micro heat pipes are small structures that will be used to cool micros cale devices. They function much like their conventional counterparts, with a few exceptions, most notably the absence of a wick. It is expe cted that water-filled micro heat pipes will be able to dissipate heat fluxes on the order of 10-15 W/cm2 (100,000-150,000 W/m2). This work addresses the modeling of a micro heat pipe operating under steady-sta te conditions. A one-dimensional model of the evaporator and adiabatic sections is developed and solved numerically to yield pressure, veloc ity, and film thickness information along the length of the pipe. Inte rfacial and vapor shear stress terms have been included in the model. Convection and body force terms have also been included in the momentu m equation, although numerical experiments have shown them to be negli gible. Pressure, velocity, and film thickness results are presented al ong with the maximum heat load dependence on pipe length and width. Bo th simple scaling and the model results show that the maximum heat tra nsport capability of a micro heat pipe varies with the inverse of its length and the cube of its hydraulic diameter, implying the largest, s hortest pipes possible should be used.