posted on 2021-12-30, 16:33authored byTanya Liu, Mehdi Asheghi, Kenneth E. Goodson
As
electronic device power densities continue to increase, vapor
chambers and heat pipes have emerged as effective thermal management
solutions for hotspot mitigation. A crucial aspect of vapor chamber
functionality depends on the properties of the microporous wick that
drives heat and mass transport within the device. While many prior
studies have focused on the optimization of these porous structures
to increase the maximum capillary-limited dryout heat flux, an equally
important aspect of porous wick design is the minimization of the
thermal resistance above heated areas. Segmented wicks with geometries
that vary along the length of the wick are attractive candidates that
can potentially be used to fulfill these simultaneous design goals.
Previous studies on bisegmented wicks with only two distinct adiabatic
and heated region geometries, however, have shown mixed results regarding
the degree of performance benefit over homogeneous wicks. In this
work, we present a systematic modeling approach to investigate the
optimal composition of segmented micropillar wicks comprising multiple,
discrete regions of graded geometry. Using a genetic algorithm, we
generate Pareto fronts of optimal segmented wick distributions that
maximize the dryout heat flux and minimize the thermal resistance
for a given heating configuration. We find that optimal, graded segmented
wicks are capable of dissipating dryout heat fluxes more than 200%
higher than baseline homogeneous wicks with significantly lower thermal
resistance. The sensitivity of the wick performance to the total number
of geometry segments is found to vary depending on the desired heat
flux and thermal resistance operating regimes.