Heat transfer by high-frequency oscillations: A new hydrodynamic technique for achieving large effective thermal conductivities

Abstract

Heat transfer between two fluid reservoirs maintained at different temperatures and connected to each other via a capillary bundle is examined when the fluid within the capillaries is oscillated axially. Very large effective axial heat conduction rates, exceeding those possible with heat pipes by several orders of magnitude, are found to be achievable. A laminar hydrodynamic theory is developed to describe the phenomenon and to show that the enhanced heat conduction is one involving radial heat transfer across very thin Stokes’s boundary layers existing in these flows. Experimental measurements using water as the working fluid show effective thermal diffusivities up to 17 900 times those existing in the absence of oscillations. Since the process involves no net convective mass transport, it offers considerable promise as a means for the rapid removal of heat from radioactive fluids.