An Alternative Design Space for High-Power Wick-Type Evaporators for Electronics Cooling

High power spacecraft have long relied on Loop Heat Pipes (LHPs) for passive thermal management. Performance of LHPs and other evaporative cooling systems has historically been governed by a porosity/ permeability tradeoff, which both limits performance and constrains manufacturing approaches. In this work, we unify prior models of wetting, meniscus formation, and capillary evaporation, to demonstrate these surface phenomena act as independent, separately tunable parameters governing evaporator performance, decoupled from bulk porosity and permeability. This independence enables large-pore wicks with reduced risk of clogging and a wider range of lower-cost manufacturing methods, including additive manufacturing. In a direct comparison between evaporators with identical bulk wick properties, our optimized approach provides a 42% performance improvement in conductance while maintaining the cost savings of additive manufacturing and the flight-proven long term reliability of LHPs. These results establish a pathway for additively manufactured, high-performance, low-cost passive evaporators, addressing manufacturing constraints that have limited LHP deployment in terrestrial applications such as electronics thermal management and waste heat recovery.