Critical evaluation of additively manufactured metal lattices for viability in advanced heat exchangers

The advantages offered by the stochastic metal foams when used in high-performance compact heat exchangers is evident in the open literature. Recently, there has been a surge in investigations on regular metal lattices which can be manufactured additively, because of their "potential" to provide multifunctional and tunable characteristics to heat exchangers. These lattices are also reported to lend superior mechanical properties as well. The literature, however, lacks in the critical assessment of these additively manufactured regular lattices in terms of the quality of printed parts (defects, surface roughness, etc.), their compatibility in compact heat exchangers, flow and thermal transport characteristics, and whether or not they are viable alternatives to the commercial metal foams conventionally manufactured. This paper reports different manufacturing routes for the fabrication of conventional stochastic and regular lattices and additively manufactured regular lattices, and how these technologies have evolved over the years. The additively manufactured lattices different from the commercial TKD may result in significantly higher interstitial heat transfer coefficient. Further, the design freedom allows different porosities through which higher effective thermal conductivity can be achieved. The usage of regular lattices in tube-heat exchangers, as wicks in heat pipes, heat transfer enhancement features in boiling heat transfer and transpiration cooling mechanisms of turbine blades as an alternative to conventional technologies is promising. The role of inherent surface roughness in dictating the thermal and flow transport in additively manufactured lattices, especially for multi-phase flow applications, should be studied in more detail. (C) 2020 Elsevier Ltd. All rights reserved.