Optimization of Heat Pipe Thermal Transport Using Axially Graded Capillary Wick Structures

One strategy for improving heat pipe heat transport performance will be discussed in detail. Using an axially graded wick, in which the capillary pore radius is varied as a function of axial position, the liquid pressure drop can be reduced allowing for increased heat transport. A one-dimensional analytical model is presented showing how the optimal continuously graded wick profile is developed for the case with constant vapor pressure and adverse (against gravity) orientation. General results are presented in terms of nondimensional parameters. For a particular case where the evaporator and condenser are each one-quarter of the length of the heat pipe, the optimal graded wick is capable of transporting over 5.6 times more power than an optimal uniform wick. In the worst case, the graded wick can transport over 3.3 times as much power as a uniform wick.Copyright © 2005 by Thermacore International, Inc.