Analysis of superheated loop heat pipes exploiting nanoporous wick membranes



The design and analysis of plant-inspired loop heat pipes (LHPs) that would exploit nanoporous membranes to allow for operation with large capillary pressures and superheated liquid are presented. The operating concepts of this superheated loop heat pipe (SHLHP) resemble the transpiration process in vascular plants: reduction of pressure in leaves drives sap flow up from the roots and overcomes gravity, viscous drag, and reduced chemical potential of water in subsaturated soils. We present a model for steady-state operation and a linear response analysis of both the conventional and superheated designs. Our analysis shows that these SHLHPs could: (1) extend the limitations of conventional LHPs imposed by thermodynamic properties of the working fluid, (2) provide efficient heat transfer over long distances and against large accelerations, and (3) allow for operation in a subsaturated state that would eliminate the thermal resistance and entrainment effect of the liquid film of conventional designs. © 2013 American Institute of Chemical Engineers AIChE J 60: 762–777, 2014