Surface Roughness Effects on Heat Transfer in Additive Manufactured Microchannels: A CFD Study

Microchannel heat exchangers are widely used in applications where compactness and efficient heat transfer are essential. The difficulty of producing metal microchannels with conventional techniques leads to the adoption of additive manufacturing, such as Direct Metal Laser Sintering (DMLS), which offers unprecedented design freedom but introduces relevant surface roughness, impacting heat transfer phenomena. The objective of this research is to methodically examine the impact of roughness factors on heat transfer through Computational Fluid Dynamics (CFD) analyses. In particular, the parametric study focuses on one specific spatial parameter, the roughness Correlation Length (CL), to consider the spatial distribution of surface features. This parameter offers a more thorough analysis than the commonly used Average Roughness (Ra) and Root Mean Square Roughness (Rq). Specifically, two types of rough surfaces are investigated: isotropic and anisotropic, to capture the complex interplay between surface roughness and heat transfer more accurately. This research advances understanding regarding the effects of surface roughness on heat transfer, advocating for the adoption of comprehensive spatial parameters for its accurate characterization. Additionally, the findings provide crucial insights for optimizing thermal management systems, guiding engineers in improving heat transfer efficiency in additively manufactured microchannels.