One‐Piece Stainless‐Steel 3D Printed Minichannel Evaporators using Flow Boiling Carbon Dioxide

New concepts are required for high‐performance minichannel evaporators with low mass and reduced size involved in the cooling of cylindrical or conical surfaces. The development of one‐piece stainless‐steel evaporators using flow boiling CO2 for the cooling of conical copper test specimens heated by a foil heater element is presented. The specimens mimic a mobile cooling device used in high‐energy and particle physics. The stainless‐steel evaporators were manufactured with a state‐of‐the‐art 3D stainless‐steel printer via selective laser melting. The computer‐aided design and the construction of this new type of evaporators are described. A dedicated two‐phase accumulator controlled loop filled with liquid CO2 was developed, it allowed for operating four parallel connected evaporators. Cooling efficiency and manufacture reproducibility were experimentally investigated by applying different thermal loads and refrigerant mass flows. Stainless‐steel 3D printing proved to be a promising technology for the manufacture of one‐piece minichannel evaporators using flow boiling CO2 as working fluid. Such evaporators are particularly interesting for the refrigeration of surfaces exhibiting complex geometries. They are manufactured as a one‐piece element and can be easily integrated in two‐phase accumulator controlled loop.