Heat exchanger manufacturers are constantly researching for new techniques that enhancement the heat transfer performance. A possible solution is the use of open-cell metal foams as substitute for the conventional fins. The major advantages of foams are low density, good rigidity, high thermal conductivity and huge value of surface/volume ratio. For these reasons, metal foams are applied in several fields such as heat exchangers, fuel cells, heat sinks and solar thermal plants. In order to create new systems in reduced volumes, it is necessary the use the aluminum foams because they are characterized by a great specific area surface that allow to obtain compact heat exchanger with high thermal performance.

A numerical investigation has been accomplished to analyze the thermal and fluid dynamic behaviors of a tubular heat exchanger partially filled with aluminum foam. The Darcy – Brinkman - Forchheimer flow model and the thermal non-equilibrium model (LTNE) for the energy are used to accomplished two-dimensional simulations on metal foam heat exchanger. The metal foam, in particular an aluminum foam, is assumed homogeneous and isotropic, the thermal and physical properties of the fluid and solid phases are considered constant and viscous dissipation and buoyancy force are neglected. The foam is characterized by porosity and (number) pores per inch respectively equal to 0.9353 and 20. The heat exchanger is analyzed with different thicknesses along the fluid flow of the same metal foam in order to study the behavior of the partially filled system for assigned tube diameter. The heat exchanger system at different mass flow rates is analyzed with a fixed surface tube temperature and the thermal contact resistances between the tube surface and foam is neglected. The finite volume method is applied in order to obtain the solutions of the governing equations. As computational domain is employed half of a single tube partially enclosed in the aluminum foam with a upstream and downstream extended domains. Ansys Fluent commercial code is used to carry out the numerical investigations. The SIMPLE algorithm is accomplished for the pressure-velocity coupling; the least square cell is used to evaluate the gradient evaluation for the spatial discretization. The pressure calculation is done by means of the PRESTO algorithm; the second order upwind scheme is used for energy and momentum equations. The results are given as heat transfer rates and mechanical powers. Furthermore, the ratios in terms of thermal and mechanical power are showed for the schemes partially and totally filled in order to understand the most convenient configuration. Finally, the temperature and pressure fields are presented.


Numerical Investigation on a Compact Heat Exchanger Partially Filled With Metal Foam

Division / Sponsors: 
Heat Transfer Division (HTD), Fluids Engineering Division (FED)

Heat Transfer Summer Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/HT/HT2020/volume/83709

18th International Conference on Nanochannels, Microchannels, and Minichannels
Paper Proceedings: https://asmedigitalcollection.asme.org/ICNMM/ICNMM2020/volume/83693

Fluids Engineering Division Summer Meeting
Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2020/volume/83716

HT-ICNMM2020 - Virtual Conference, SHTC - Virtual Conference, FEDSM2020 - Virtual Conference

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