Multimodal freezing system for cryogenic 3D printing

Cryogenic 3D printing (Cryo-3DP) technique is used to realize the frozen 3D objects by layered deposition of the liquids inside an insulated chamber. The operating temperature of the process ranges from − 20 to − 25 °C. Cryo-3DP demands high cooling rates initially to reach the process temperature followed by lower cooling rates to sustain it. Multimodal freezing system proposed in this study uses more than one cooling mode that helps in achieving the variable cooling rates. The present system uses two modes of cooling, viz., vapor compression refrigeration (VCR) and CO₂ injection. A detailed design of the multimodal freezing system is carried out for the chamber size of 200 mm × 200 mm × 195 mm. The performance of the system is analysed numerically. The results were experimentally validated using the prototype of the multimodal system developed as a part of the present study. The results show that the multimodal system reduces the initial cooling time substantially by providing a high cooling rate that rapidly cools the chamber to initiate the cryo-3DP. VCR system provides a low but sustained cooling rate that maintains the desired temperature. The present study proves the significance of multimodality in cooling system that is fit to deploy in a commercial cryogenic 3D printer.