1.3) Porous structures
The heat pipe porous structure has two main functions: to return the condensed fluid to the
evaporator, and to assure that the working fluid is distributed through the entire volume of
the heat pipe. The fluid returns to the condenser through the capillarity of the porous structure.
Therefore, in order to enhance the the capillar capacity, it is necessary to utilize materials with
small pores. On the other hand, reduced pores enhance the working fluid flowing resistance through
the porous media, which raises the thermal resistance of the device as a whole.
The porous medium has interconnecting porosity, which allows fluids to be transported though it.
Metallic, ceramic, polymeric, and composite materials can be used, and chemical composition choices
will depend on the device project and construction factors.
Currently, LEPTEN/LABTUCAL have been developing in cooperation with the Materials Laboratory
(LABMAT/UFSC), Copper and Nickel powder syntherized capillary structures, in a Plasma Assisted
Debinding and Sintering (PADS) oven. In order to obtain the porous medium, two powder molding
techniques are used: metallic powder injection (a promising technique for industrial production
of porous medium), and the traditional technique of loose sintering.
