Experimental investigation of the performance of an Industrial-Grade Schwartz-D heat exchanger

Advancements in additive manufacturing (AM) technology have enabled the fabrication of innovatively designed heat exchangers (HXs), such as those based on triply periodic minimal surfaces (TPMS) structures. Despite extensive research on TPMS-based HXs, the manufacturability and the thermal–hydraulic performance of industrial-grade TPMS-based HX, characterized by meter-scale sizes, remain unexplored. In this study, a 159 mm × 500 mm (diameter × length) HX designed with the Schwartz-D (S-D) structure was successfully fabricated using 316L stainless steel via AM. The printing quality was evaluated in terms of size precision and surface roughness. Then, the thermal–hydraulic performance of this HX was experimentally investigated using water as the working fluid. The flow resistance correlation for the S-D structure was obtained and the transition between flow resistance regimes in the S-D structure without baffles was identified. The heat transfer correlation for the S-D structure without baffles was developed for the Reynolds number (Re) ranging from 1,000 to 25,000. This correlation accurately predicts simulation and experimental data from other studies, with an error of less than 20 %. The simulations show that the flow in the S-D structure exhibits significant eccentricity across all cross-sections, with the shifting position of the eccentric flow at different locations enhancing heat transfer between the fluid and the wall. Compared to an optimized helical tube, the S-D structure without baffles achieves up to a 150 % increase in the Nusselt number (Nu) at the same Re. Furthermore, the S-D HX has a 2–3 times higher overall heat transfer coefficient with 52 %–95 % smaller volume than conventional optimized shell-and-tube HXs under similar flow rate conditions. Overall, this work demonstrates the TPMS-based HX performance advantages on a large scale and underscores its potential for industrial-grade HX miniaturization.