State-of-the-art in heat exchanger additive manufacturing

The progress in additive manufacturing (AM) sector has transformed the ways in which heat exchangers (HXs) can be fabricated. The complex and freeform designs which could not be realized by conventional manufacturing routes can now be realized through AM technologies. The weight, volume, load bearing capabilities and manufacturing cost reductions are some of the other benefits that AM can provide over the conventional manufacturing. The relative benefits of using AM to make heat exchangers, however, are accompanied by various inherent challenges related to the process parameters, surface quality and material choice. A comprehensive understanding of the fabricated HX surface quality is imperative to explain the resulting flow and thermal characteristics. This study focusses on analyzing the thermal-hydraulic performance of additively manufactured HXs such as rough surfaces, microchannels, surface area and turbulence promoters, cellular materials, heat pipes, turbomachinery cooling designs, and jet impingement cooling concepts. The review of the existing literature suggests that the inherent surface roughness is the key consideration across different types of heat exchanger configurations manufactured by metal additive manufacturing. Significant deviation of the manufactured dimensions is observed relative to the intended design, especially when the dimensions approach the manufacturing limits. With the continuously improving AM technologies in terms of final product surface quality, dimensional accuracy, and realization of smaller length scales with accuracy, one can expect exciting times ahead in heat exchanger development and to this end, the review paper may serve as an essential reference tool. (c) 2021 Elsevier Ltd. All rights reserved.