Abstract: Heat pipes are essential in every modern computer because they are reliable and passive devices per their reliance on capillarity, have an effective thermal conductivity 10-to-100 times that of a solid copper rod of same diameter and possess a sufficiently-high maximum heat load. We develop a semi-analytical procedure to capture the effect of slowly varying (streamwise) meniscus curvature on the flow resistance of the adiabatic section of an axial-groove heat pipe (AGHP). The relevant small parameter is the pitch of the grooves divided by the length of the adiabatic section. Prescribed are the geometry of the AGHP, its orientation with respect to the gravity vector and relevant thermophysical properties (and, by implication, the capillary pressure driving the flow). Our requisite consideration of the evaporator and condenser sections of the AGHP invoke the standard assumption that the radius of the meniscus in them is a constant equal to that of the lands between menisci. The deviation of the meniscus geometry from a circular arc (relative to an origin at the radial center of the AGHP) in the adiabatic section is captured using a boundary perturbation, where the small parameter is the protrusion angle between the arc defining a meniscus and that corresponding to the radius of an adjacent land. A local analysis ensures the singularities at the triple contact lines are resolved. Our procedure enables more accurate prediction of the components of the capillarity-limited maximum heat load in an AGHP and the corresponding thermal resistance of its adiabatic section.

Bio: Marc Hodes earned his BS, MS, and PhD degrees in Mechanical Engineering from the University of Pittsburgh, the University of Minnesota and the Massachusetts Institute of Technology, respectively. He spent 10 years at Bell Labs Research (Murray Hill, NJ) and has spent extended periods in residence at the National Institute of Standards and Technologies (NIST) and the University of Limerick. He joined the Department of Mechanical Engineering at Tufts University in 2008 where he is a Professor and the Director of Graduate Studies. His Groups’ research there has been funded by government agencies, e.g., NSF, DARPA and DoE, and industry, e.g., Huawei and Google. Research interests are in Transport Phenomena and, over the course of his career, four thematic areas have been addressed: 1) the thermal management of electronics, 2) mass transfer in supercritical fluids, 3) analysis of thermoelectric modules, and 4) momentum, heat, mass and charge transport in the presence of apparent slip. Pertinent to the latter topic, Marc runs the Red Lotus Project with Professors Darren Crowdy and Demetrios Papageorgiou in the Department of Mathematics at Imperial College London, where he is a regular, long-term Academic Visitor. Professor Hodes is the sole- or co-author of over 50 papers in archival journals on transport phenomena. Together with Dr. Georgios Karamanis, Marc spun Transport Phenomena Technologies, LLC,  out of Tufts University in 2017, which is currently focused on a Phase II NSF SBIR project on conforming vapor chambers for the thermal management of electronics and various consulting projects.

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