An experimental investigation on hydraulic and thermal performance of SLM-printed Mini channels using different printing parameters

Additive manufacturing (AM), particularly selective laser melting (SLM), has brought revolutionary degrees of freedom to the design of compact heat exchangers. The previous studies on pressure drop and heat transfer characteristics of AM heat exchangers primarily concentrated on numerical simulation, with surface morphology and porosity conditions typically based on idealized assumptions. However, variations in empirical printing parameters among different AM manufacturers lead to unignorable differences in the hydraulic and thermal performance of the SLM-printed heat exchangers with the same geometric structure. This study experimentally investigates the pressure drop and heat transfer characteristics of circular SLM-printed horizontal mini channels fabricated by three different sets of printing parameters commonly used by AM manufacturers. Additionally, the experimental results were also compared with the pressure drop and heat transfer data of traditional cold-rolled stainless steel tubes. The experimental results demonstrate that the different combination of printing parameters (such as laser power, layer thickness, laser spot, etc.) results in notable differences in surface roughness and internal porosity of the printed samples, which directly affects the hydraulic and thermal performance. The SLM-printed channel with the best performance showed a 30.62% improvement in the efficiency index j j p / f f p compared to the channel with the worst performance across the entire flow regime. Hence, the findings of this study not only reveal that the selection of printing parameters had a significant effect on hydraulic and thermal performance but also provide a reference for thermal engineers in designing and developing SLM-printed heat exchangers and thermal management devices. • Different AM manufacturers vary in the selection of key printing parameters • The performance of SLM-printed channels is a strong function of printing parameters • The best SLM-printed channel is 30.62% more efficient on average than the worst