Additive Design and Manufacturing of a Composite Polymer Heat Exchanger Jake Boxleitner
Project Overview ARPA-e ARID Program Power plant cooling HVAC applications kw/kg and $/kw Page 3
Project Overview Common additive processes Filament Resin Powder Fused Filament Fabrication (FFF) Continuous Liquid Interface Production (CLIP) Stereolithography (SLA) Selective Laser Melting (SLM) Binder jetting Page 4
Project Overview Performance Weighted Cost ($/kw) 160 140 120 100 80 60 40 20 reduced $/kg Phase 1 result - pin fin Phase 1 result - airfoils Phase 2 - subfins conventional heat exchangers Phase 2 - tapered fins 0 0 1 2 3 4 5 6 7 8 Mass-weighted Performance (kw/kg) constant $/kg Page 5
HX Design and Modeling Heat Exchanger Topology 6 by 6 frontal area Air Lytron 6110 Water Microstructure Macrostructure Page 6
HX Design and Modeling Heat flow and resistance network T water R conv Water channel qሶ Air channel Fins Walls R wall R unfinned R finned T air Page 7
HX Design Thermal model Conduction resistance Neat polymer conductivity: 0.1-0.3 W/m-K Wall thickness Convection resistance Heat transfer coefficient Feature size Pressure drop T water R conv R wall 5.5 mm R unfinned R finned 1.2 mm T air Page 8
Manufacturing University of Wisconsin Polymer Engineering Center FFF printers Makergear M2 Aon3D M Cosine AM1 Page 9
Manufacturing Nomenclature and build orientation Filament Nozzle Print direction (x, y) Nozzle diameter Layer height Z Y X Build Direction (z) Page 10
Manufacturing Geometry printing process Microstructure channel Microstructure kazoo Page 11
Manufacturing Test Channel Slicing Build Direction (z) Page 12
Manufacturing Test Channel Slicing Build Direction (z) Layer A cut plane Layer A Layer A tool path Page 13
Manufacturing Test Channel Slicing Build Direction (z) Layer A cut plane Layer A Layer A tool path Page 14
3 Manufacturing Tool path comparison Uncontrolled tool path Optimized tool path Page 15
3 Manufacturing uct geometry analysis 5.5 mm 1.2 mm Page 16
3 Manufacturing uct geometry analysis 0.2 mm 0.4 mm Ø0.4 mm Page 17
3 Manufacturing Evolution of the kazoo 1 2 3 4 Page 18
3 Manufacturing Kazoo failure modes fin-to-wall connection wall Page 19
3 Pressure Testing Pressure Testing Page 20
3 Pressure Testing Shot on iphone 6 Addition equipment and software not used Page 21
3 Pressure Testing Page 22
3 Pressure Testing Design of Experiments Setup Layer Height Print Speed Extrusion Ratio Extrusion Temperature Filament Temperature Nozzle Print speed Extrusion Ratio Layer height Nozzle diam. Layer height Page 23
3 Pressure Testing Design of Experiments Results Page 24
3 Pressure Testing Kazoo formic acid treatment Page 25
Manufacturing As-printed airfoil heat exchanger Page 26
4 Model Validation Test loop schematic HX Water DP RTD Hydrostatic Pump Pump Nozzle DP RTD RTD Flow Meter HX Frontal Area: 70 mm x 70 mm HX HX Air DP RTD Hot Water Bath Pressure Gauge Page 27
Model Validation ASHRAE Standard 33 almost Page 28
Model Validation Test results and model prediction Page 29
Thermal model Material conductivity and minimum wall thickness trade study Page 30
Overview of Project Performance Weighted Cost ($/kw) 160 140 120 100 80 60 40 20 reduced $/kg Phase 1 result - pin fin Phase 1 result - airfoils conventional heat exchangers 0 0 1 2 3 4 5 6 7 8 Mass-weighted Performance (kw/kg) constant $/kg Page 31
Material Development Carbon fiber Copper spheres Copper fibers Aluminum flake Graphite flakes Page 32
Material Development Recall heat flow and resistance network Water channel k3 k2 k1 Air channel k2 k1 Fins Walls k1 Fiber alignment Flake alignment Oriented carbon fibers Page 33
3 Material Development Nozzle clogging with filled polymers Flow-ability Fibers Spheres Page 34
3 Material Development Material performance comparison Page 35
Project Overview Performance Weighted Cost ($/kw) 160 140 120 100 80 60 40 20 reduced $/kg Phase 1 result - pin fin Phase 1 result - airfoils conventional heat exchangers Phase 2 - tapered fins 0 0 1 2 3 4 5 6 7 8 Mass-weighted Performance (kw/kg) constant $/kg Page 36
4 Geometry Development CFD unit cell definition and boundary conditions u, T a,in T w Page 37
4 Geometry Development CFD geometry correlations and thermal model friction factor from correlation Nusselt from correlation 12 10 8 6 4 2 0 0 2 4 6 8 10 12 1.5 1.25 1 0.75 0.5 0.25 Nusselt from CFD +20% +20% -20% -20% Standard linear regression Nonlinear regression Standard linear regression Nonlinear regression Nu, f T water R conv R wall R unfinned R finned 0 0 0.25 0.5 0.75 1 1.25 1.5 friction factor from CFD Felber, R., Design, simulation, and testing of novel air-cooled heat exchangers manufactured by fused filament fabrication, M.S. thesis, Dept. of Mech. Eng., Univ. of Wisc., Madison, WI, 2017. T air Page 38
Geometry Development Tapered pin fins and heat flow comparison Water Flow Air Flow Tapered pin Straight pin Page 39
Manufacturing Tapered pin fin build orientation Page 40
Manufacturing Tapered pin fin tool path Layer A Layer B Layer C Page 41
Manufacturing Tapered pin fin tool path Layer A Layer B Layer C Layer A Layer B Layer C Page 42
Manufacturing Tool Pathing Geometry Comparison Airfoils Tapered Fins Page 43
Manufacturing Tool Pathing tapered pin fin Page 44
Geometry Development Thermal Advantages Page 45
Geometry Development Water Side Behavior Page 46
Geometry Development Water Side Behavior Water side thermal gradients Page 47
Geometry Development Hollow-through tapered pin fins Page 48
Geometry Development Revisit iterative printing process Page 49
Geometry Development Page 50
Geometry Improvements Tapered pin fin test results and thermal model comparison to airfoil results Page 51
Project Overview Performance Weighted Cost ($/kw) 160 140 120 100 80 60 40 20 reduced $/kg Phase 1 result - pin fin Phase 1 result - airfoils conventional heat exchangers Phase 2 - tapered fins 0 0 1 2 3 4 5 6 7 8 Mass-weighted Performance (kw/kg) constant $/kg Page 52
Future Work Geometry development Material development Tool Pathing Streamlined, tapered, and decoupled fins Filled and flow-able materials Page 53
Thank you for your attention Polycarbonate Aluminum Flake Tapered Pin Fin Heat Exchanger Page 54
Appendix Page 55
Other Additive Processes - SLM A Page 56
Other Additive Processes - CLIP A Page 57
Tool Paths A Page 58
Water-side CFD Modeling Flow misdistribution: 4.3% deviation from average flow rate per channel A Section A-A A Page 59
3 Manufacturing Printer hardware issues Milestone due: 11/30/17 Feed gear abrasion This leads to a reduction in the effective diameter of the gear, leading to under-extrusion. These grooves represent ~2% reduction in the extrusion ratio. 2 weeks of printing The Makergear was adjusted to use these hardened steel gears Page 60
3 Manufacturing Printer hardware issues Nozzle abrasion: the actual extruded bead becomes wider and shorter than the nominal bead due to abrasion by the filler. Nominal 0.35 mm nozzle grew to 0.7 at the exit! This leads to leaks between the layers due to an incomplete fill in the z-direction. A hardened steel nozzle shows no wear after several weeks. Nominal Bead Actual Bead Page 61