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Microchannel Heat Exchangers
High-pressure hydroforming reigns in the future of microchannel heat exchangers
Microchannel heat exchanger prototype formed by FluidForming sheet metal hydroforming . Image courtesy of FluidForming Americas , LLC .
FluidForming is a high-pressure , bladder-free sheet metal hydroforming process . The process has been used by product developers and manufacturers for rapid prototyping and low- to medium-volume production runs . Working closely with product developers at Evicient , the team at FluidForming Americas helped optimize part design using Autoform ® finite element analysis , and created production-ready prototypes of a counterflow , flat-plate , microchannel heat exchanger for testing , analysis , and product development .
About the author
Jurgen Pannock is the co-founder and CTO at FluidForming Americas , LLC . He received his Ph . D . in Engineering from the University of Maryland , College Park . He went on to work for the Whirlpool Corporation , where he was employed as the Technology Manager , Global Technology Manager in Air Treatment , Director of Design for Safety , and Director of Advanced Development Refrigeration .
By Jurgen Pannock , Ph . D ., Chief Technical Officer , FluidForming Americas LLC , and Jesse Killion , Co-Founder , Evicient LLC
The FluidForming metal forming process was selected to form prototypes of microchannel heat exchangers from 28 gauge nickel plated 1006 steel . The dimensions of the prototype panels were 280 mm × 115 mm . The plates included headers to distribute the working fluids and 55 channels 1.7 mm wide × 0.2 mm deep . A forming pressure of 30,000 psi was employed , though the process can achieve pressures up to 60,000 psi . The fundamental benefit of this prototype — and all microchannel heat exchangers — lies in the fact that , as the cross-sectional area decreases , the surface area to cross sectional area of the media increases and the heat transfer coefficient increases . In addition , smaller channels can withstand higher pressures with thinner walls than larger channels . Microchannel heat exchangers therefore provide better efficiency with less material and more space efficient
designs . Thus , the benefits of microchannel heat exchanger include :
• Efficiency : pound for pound significantly more efficient than traditional heat exchangers .
• Size : Typically significantly smaller than conventional heat exchangers .
• Fluid savings : Depending on the use , the amount of operating fluid on the inside the tubing can result in cost savings .
Creating microchannel geometries in flat-plate heat exchangers requires precise dimensional control . Creating prototypes is typically a capital-intensive process . The process in question only requires tooling on one side of the material and inherently has high dimensional accuracy and repeatability .
Problem : rapid prototyping and part functionality High tooling costs , elaborate machine set-up , prohibitively complex part design , and forming inconsistencies
Microchannel prototypes prior to final assembly . Image courtesy of FluidForming Americas , LLC .
26 Heat Exchanger World September 2024 www . heat-exchanger-world . com