Cellular Materials – CMs

Over the past four decades, there has been increased attention in the research of transport phenomena in porous media due to its importance in many engineering and industrial sectors. Major advances have been made in modeling fluid flow, heat, and mass transfer through a porous medium, including clarification of several important physical phenomena.

Cellular Materials (CMs) are a very promising and relatively new class of porous materials. Hence, CMs are relatively novel materials that demonstrate commitment in a wide range of state-of-the-art mechanical/biomechanical/thermal engineering fields. Among the various CMs, it is possible to observe two kinds of CM based on topology, namely, cell-size (stochastic or periodic) and pore-type (open or closed).

In recent years, thermal researchers focus has changed to novel materials for the improved efficiency and better performance in the energy transfer systems. Metal Periodic Cellular Lattice (PCL) material can be classified as porous media with typically high porosity that consists of tortuous, irregular shaped flow passages. Metal PCL materials are used in a wide range of heat-transfer equipment. Due to their nature and structure, PCL material is used in many thermal management applications due to its high surface area to volume ratio, in the order of 10,000 m2/m3.

The metal PCL material structure with 90%-98% porosity has the desirable qualities of a well-designed heat exchanger, i.e. a high specific solid–fluid interface surface area, good thermally conducting solid phase, and a tortuous coolant flow path to promote mixing. Therefore, metal PCL material are such kinds of materials which can be considered as a replacement of conventional fins of compact heat exchangers used in aerospace applications and better heat transfer values in comparison to the conventional fins with a marginally increased pressure drop values.

The metal matrix of PCL material can be manufactured from a high thermally conducting solid such as aluminum or copper, which, merely by its presence in a static fluid, dramatically increases the overall effective thermal conductivity of the fluid-system (the overall effective thermal conductivity of the solid–fluid system can be most generally described by the porosity and the conductivities of the fluid and solid phases). Flow through porous media has been studied in detail ever since 1856. Porosity and structure topology of metal PCL material are the only parameters that affect the thermal-hydraulic performance of thermal equipment equipped with metal PCL material.

In one of the most recent researches in the field of cellular material thermal sciences, computational numerical simulations were conducted to clarify and explore the influences of PCL morphological parameters–such as lattice structure topology and porosity value–on the thermal-hydraulic characteristics of the novel compact heat exchanger has led to a deeper understanding of the superior heat transfer enhancement ability of the PCL structure:

A novel trussed fin-and-elliptical tube heat exchanger with periodic cellular lattice structures

[Download]

Dr. Babak Lotfi

Assistant Professor

Research Affiliate of Lund University, Sweden