In the present work, diffusion bonding technology used for fabrication of pulsating heat pipes (PHP) in a high-vacuum, highpressure and high-temperature furnace is discussed. Seven different configurations of PHPs were manufactured, subjected to different fabrication parameters. PHPs with 10 and 26 parallel channels of circular and square cross-sectional areas were constructed. In addition, a PHP with a novel cross-sectional channel geometry, composed by a circular area with lateral grooves, which is easily fabricated by the present technology, is proposed. The deformation of the geometries of the channel cross sections was observed. The square channel PHP showed large deformation, while the deformations of the circular ones, including the new proposed geometry, were small. The distribution of the PHPs along the matrix in a single bonding cycle showed to be a very important parameter: Those PHPs produced in parallel presented some deformation and leakage problems, while those made by stacking mode did not presented any leakage. Scanning electron microscopy and optical microscopy were used to assess that diffusion bonding is a very suitable and promising technology for the fabrication of PHPs. The thermal tests showed that the grooved circular channel PHP presents higher thermal performance.
Heat pipe design and selection require specialist knowledge due to numerous possible combinations and restrictions that should be taken into account. The general objective of this work is to design a Specialist System that assists future engineers in material and working fluid selection for a suitable heat pipe application, based on the technical operating requirements. The methodology consisted of a qualitative perspective through interviews with two specialist engineers in the heat pipes area. The resulting information from the interviews was organized into a library, working as a source for the specialist system. In addition, several books from the literature completed the information in the library. Based on the operating conditions and the provided library, the program recommends suitable materials and working fluids and the necessity of porous media for the application, similar to a consult with a heat pipe specialist. The new expert system can be a tool for researchers and engineers in heat pipe design as passive control systems, providing more suitable solutions for each application.
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