Analysis of Transport Phenomena in Optical Fiber Manufacturing
Ranga Pitchumani Advanced Materials and Technologies Laboratory Department of Mechanical Engineering University of Connecticut Storrs, Connecticut http://www.engr.uconn.edu/amtl
Presented at Corning Incorporated • August 6, 2008
Outline
Introduction to Advanced Materials and Technologies Laboratory Optical Fiber Drawing Numerical Modeling Analysis of dopant concentration and refractive index profile evolution during manufacturing Simulation and optimization under uncertainty Analysis of coating thickness variations A sampling of other recent research activities in the Laboratory
Advanced Materials and Technologies Laboratory • University of Connecticut
Advanced Materials and Technologies Laboratory MISSION: Conduct research towards improving the fundamental description and understanding of complex physical phenomena governing materials processing and design, and emerging technologies. The fundamental description and understanding are applied towards practical development, design, optimization and control. LAB PERSONNEL: 6 Graduate Students, 1-2 Postdocs 2 Undergraduate Students 2-3 High School Students each summer RESEARCH AREAS: Advanced Materials Processing Microsystems and Microfabrication Fuel Cells/Energy Design and Manufacturing Core Sciences $6M total funding Advanced Materials and Technologies Laboratory • University of Connecticut
Representative Recent Projects Polymer and Composite Materials Processing (NSF, ONR, AFOSR) Processing of thermosetting and thermoplastic-matrix composites Fundamental transport property determination: Conductivity; Permeability Investigations on microscale and nanoscale phenomena Process optimization and control using physics-based models Microsystems (Sandia National Lab, NSF) Fabrication of high-aspect ratio microstructures (HARMs) Reliability of microdevices Fuel Cells (Army) Novel cell designs–functionally graded electrodes and catalyst layers Passive fuel cells and mFuel Cells Cell modeling and performance optimization under uncertainty Measurement and prediction of contact resistance Information Technology in Materials Processing (NSF-ITR) Advanced computing techniques for rapid simulation and optimization of materials processing under uncertainty–Application to Optical Fiber Drawing Life Prediction of Aircraft Engine Components Using Neural Networks (P&W) New Material Designs for Contact Heads and Ablative Walls in Electrical Circuit Breakers (GE)
Advanced Materials and Technologies Laboratory • University of Connecticut
Optical Fiber Drawing
nr(r)
coating
Optical fibers are used to transmit light signals The manufacturing process consists of: fiber drawing, cooling and coating steps. Preform is SiO2 doped with oxides of Ge, P or B, with an initial concentration profile. The index of refraction profile is a function of the dopant concentration which evolves during the drawing and cooling steps; at the end of the cooling step, the index of refraction profile is finalized. The cooled fiber is coated with a polymer.
Advanced Materials and Technologies Laboratory • University of Connecticut
Optical Fiber Drawing Model Conservation equations are formulated in the glass and surrounding fluid domains; It is assumed that the flow and temperature fields are not significantly affected by the dopant (taken to be GeO2).
Continuity
Momentum
Energy
Species (Dopant Diffusion)
u 1 (rv) 0 z r r u 2 1 (ruv) p u 1 u v 2 m rm z r r z z z r r r r ( uv) 1 (rv 2 ) p u v 2 v 2mv m rm z r r r z r z r r r r 2
( C p uT) 1 rC p vT T 1 T k rk z r r z z r r r u 2 u 2 v 2 u v 2 m2 r r z z r
E (uc) 1 (rvc) c 1 c D rD ; D D0 exp z r r z z r r r kB T
+ Boundary and Interface Conditions
Advanced Materials and Technologies Laboratory • University of Connecticut
Optical Fiber Drawing Model The preform/fiber domain can be represented in one of two ways: 1.
A fixed necking profile given by a parametrized function (such as the logarithmic function of an 8th order polynomial, as in Lee and Jaluria, 1996)
2.
Profile that is determined as part of the solution: In approach, the necking profile is parametrized as a hyperbolic tangent function
r(z) c1 tanh c 2 z c 5 c 3 c 4
in which, the constants are determined as solution to an optimization problem seeking to maintain uniform tension (obtained from the viscous v force gradient in fiber drawing simulation) along the axis FT 3mA
z
Simulation Outputs:
Temperature, Velocity, and Concentration, profiles in the preform fiber, and fluid domains
Refractive index is calculated from the dopant concentration using the Lorentz-Lorentz equation (Huang, Sarkar, Schutz, 1978): 1 2 n ; 1
n n
2 r,i
2 r,i
1c i
2i
ci
i
Advanced Materials and Technologies Laboratory • University of Connecticut
Necking Profiles for Different Parameters
zL = 15 cm
Advanced Materials and Technologies Laboratory • University of Connecticut
Validation and Parametric Studies Y. Yan and R. Pitchumani, Int. J. Heat and Mass Transfer (2006)
Numerical simulations show good agreement to results in literature The validated numerical simulations are used to investigate the effects of non-dimensional parameters representing the flow (i.e. the Reynolds numbers), the geometry (i.e. furnace radius), and the mass transport (i.e. Peclet number of the dopant), on the drawing process by observing the surface temperature, dopant concentration, and refractive index distributions. Advanced Materials and Technologies Laboratory • University of Connecticut
Effects of Reynolds Number Y. Yan and R. Pitchumani, Int. J. Heat and Mass Transfer (2006)
Re f
u f rf
f ,m
;
T T ; T0 T
z r ; zL r(z)
As Ref increases, the fiber residence time in the furnace and cooling zones decreases, reducing the rate of temperature rise and decay in the respective zone. Increasing Ref decreases dopant diffusion and increases the radial refractive index variation.
Advanced Materials and Technologies Laboratory • University of Connecticut
Effects of Peclet Number of Dopant Y. Yan and R. Pitchumani, Int. J. Heat and Mass Transfer (2006)
The surface temperature is independent of Pe, due to the model assumption.
u f rf T T ; ; Dm T0 T z r ; zL r(z) Pe
As Pe increases, centerline dopant concentration decays less along the axis (due to poor diffusion), and the refractive index varies considerably across the radius. The results suggest that refractive index profile may be tailored to a degree through processing conditions (in addition to material choices)
Advanced Materials and Technologies Laboratory • University of Connecticut
Outline
Introduction to Advanced Materials and Technologies Laboratory Optical Fiber Drawing Numerical Modeling Analysis of dopant concentration and refractive index profile evolution during manufacturing Simulation and optimization under uncertainty A. Mawardi and R. Pitchumani, IEEE J. Lightwave Technology (2008) C. Acquah, et al., Ind. Eng. Chem. Res. (2006)
Analysis of coating thickness variations A sampling of other recent research activities in the Laboratory
Advanced Materials and Technologies Laboratory • University of Connecticut
Stochastic Analysis: Uncertain Parameters Uncertain Parameters Radiation Parameter: – Spectral, hemispherical emissivity of the silica preform, (a). The absorption coefficient a is given as a function of the wavelength . The magnitude of a is considered to be uncertain. Concentration Parameters: – Thermophysical dopant properties (temperature dependent): Diffusion coefficients: D0, E Rheological Parameters: – Viscosity of the glass melt varies with temperature following an Arrhenius relationship; the preexponential factor (m0) and the activation energy (Em)are considered uncertain. Temperature Parameters: – Furnace temperature, Tw – Cooling gas temperature, Td Parameters with uncertainties are represented as probability distributions with mean m, and standard deviation . Define: coefficient of variance /m quantifies the severity of uncertainty in the parameters represents the ―width‖ of the distribution Advanced Materials and Technologies Laboratory • University of Connecticut
Quality Parameters Considered Drawing induced defects [Hanafusa, et al. (1985)] Point defects associated with the interstitial Ge atoms (Ge E’ centers) occurs in GeO2-doped silica due to quenching from high temperatures: associated with oxygen vacancies in neighboring the Ge atoms. The concentration of the thermally induced defects, nd, is expressed as: E A n d (T) n p exp f kT V
Draw Tension [Paek and Runk (1978)] Combination of viscous force, forces due to surface tension, inertia, and shear force exerted by external fluid. v FT (r) Fm F FI Fe Fg 3mR 2 z
Residual Stress [Paek and Kurkjian (1975)]: Combination of mechanical and thermal stresses. Affects the optical characteristic of the fiber F z (r) m t (r) A2
T r
E(r,T)
1 (r,T) c (r,T)dT
TC
Index of Refraction (IR) Correction [Hibino, et al. (1989)] Residual stress affects refractive index through photoelastic effects. A correctionto the refractive index is given by:
nr Ca r Cb ( z ) Cb z r
Advanced Materials and Technologies Laboratory • University of Connecticut
Sampling-Based Stochastic Analysis Tw
Td
m0
Em
D0
ED a
Uncertain Inputs Distributions
Output Distributions nd Sampling (LHS)
zz,max Deterministic Inputs u1, u2,…uM
Nonlinear Optical Fiber Drawing Simulation
FT,max
Based on the stochastic convergence analysis, a sample size of 500 was chosen for each stochastic simulation Advanced Materials and Technologies Laboratory • University of Connecticut
max
n r r
r
n r,0 r
n r r n r,0 r 100% n r,0 r
Quality Variability Measure Typically, standard deviation is used as a measure of ―variation‖ of a distribution However, standard deviation is sensitive to outliers. In this study, a measure of variance based on percentiles values is used to quantify distribution variation. 25% 50%
75%
Interquartile Range (IQR)
Advanced Materials and Technologies Laboratory • University of Connecticut
Output Distributions
Advanced Materials and Technologies Laboratory • University of Connecticut
Output Variations
The IQRs of all output parameters pronouncedly increases with the COV of Tw. The IQRs of max. residual stress and max. refractive index variation also significantly increase with the COV of ED, while the IQR of max. tension increases with COV of Em. Advanced Materials and Technologies Laboratory • University of Connecticut
Design Windows
As input COV increases, the output variations (IQR) increases. As the wall temperature increases, the IQRs of the defects and max. refractive index variation increase, while the IQRs of the residual stress and maximum tension decrease. Advanced Materials and Technologies Laboratory • University of Connecticut
Remarks
The wall temperature is the most important of the uncertain parameters, and uncertainty in the wall temperature affects significantly the variations in all output parameters, and especially the Ge(3) defects Uncertainty in the diffusion affects the variation in residual stress and the index of refraction profile
Uncertainty in the viscosity most significantly influences the variability in maximum tension Low draw temperature is desired to minimize the variations in Ge(3) defects and index of refraction profile, while high temperature minimizes the variability in residual stress and draw tension
Advanced Materials and Technologies Laboratory • University of Connecticut
Optimization Under Uncertainty
Problem Statement:  Design problem: to maximize drawing velocity while satisfying constraints on product quality requirements in the forms of: Ge(3) defects, residual stress, drawing tension, and a desired refractive index profile, given uncertainty in parameters affecting the fiber drawing process
Advanced Materials and Technologies Laboratory • University of Connecticut
Sampling-Based Optimization Under Uncertainty
Sampler Input Parameters
Deterministic Model
Stochastic Model
Output Variabilities
Optimum Design
Optimizer
Confidence Level (pc)
The optimization problem:
Minimize : E Pc ( f (di )) di
pc
(Probabilistic Objective Function)
f
fcrit 1
Subject to: E Pc (g j ) g j,crit
(Probabilistic Constraints)
pc
cdf f
fcrit
pc is the confidence level, which allows different level of risk management. Optimization may be solved using any deterministic non-gradient based optimization method.
Advanced Materials and Technologies Laboratory • University of Connecticut
Two-Stage Optimization Problem (TSOP) C. Acquah, et al., Ind. Eng. Chem. Res. (2006)
Using the optical fiber drawing numerical model as the basis, a deterministic TwoStage Optimization Problem (TSOP) and a Split and Bound (SB) algorithm is employed to solve the optimization under uncertainty of a fiber drawing process.
Two-Stage Optimization Problem: the two stages represent the initial design stage followed by the operational stage.
In the design stage, design variables, dk, are selected and are fixed as the process runs. During the process operation, another set of variables, zi, referred to as control variables, are varied to compensate for the effect of uncertainties.
In TSOP uncertainty, the objective function is evaluated as an expected (mean) value, whereas the constraints are treated deterministically for each realization of within the domain of the uncertain parameter. The optimization problem can be expressed as: Maximize E ( V )
Tw ,Td ,ra ,c i ,z L , V
Subject to:
g1 n d (dk ,z i , j ) n d ,crit 0
j Tw ,Td ,a, m0 E m,,D0, E dk Tw ,Td ,ra ,c 0 ,zL,,u f
g2 FT (dk ,z i , j ) Fcrit 0 g3 (dk ,z i , j ) crit 0 g4 max (dk ,z i , j ) max,crit 0
z i ucg ,uig
g5 ave (dk ,z i , j ) ave,crit 0 Advanced Materials and Technologies Laboratory • University of Connecticut
Outline
Introduction to Advanced Materials and Technologies Laboratory Optical Fiber Drawing Numerical Modeling Analysis of dopant concentration and refractive index profile evolution during manufacturing Simulation and optimization under uncertainty Analysis of coating thickness variations Q. Jiang, F. Yang, and R. Pitchumani, IEEE J. Lightwave Technology (2005)
A sampling of other recent research activities in the Laboratory
Advanced Materials and Technologies Laboratory • University of Connecticut
The Coating Process Coating thickness and its variation govern the reliability of the fiber The average coating thickness can be developed analytically based on analysis of fluid mechanics of the coating polymer in the applicator Coating thickness variation has been studied mostly through experiments, with little supporting analysis The present goal is to be able to predict the thickness variations as a function of the coating process and material parameters. Advanced Materials and Technologies Laboratory • University of Connecticut
Coating Process Modeling: Problem Formulation Assumptions: Incompressible Newtonian fluid Axisymmetric laminar flow No-slip on the fiber surface
Governing Equations: u u w 0 t r z 1 ur 2 u u u p u u w m 2 r z r t r r r z 1 w 2 w w w p w g u w m r 2 t r z z r r r z
Boundary Conditions: (1) no-slip conditions at the fiber surface, (2) vanishing shear stress at the free surface, (3) stress balance at the free surface, and (4) kinematic condition Stream function: Velocity components are expressed in terms of a stream function,
Nondimensionalization:
u
1 (radial ) r z
w 1
1 (axial) r r
3 3 p pa h0 p ; ; 2 ; 4 W 02 W 0 h02 4 m g
z
z h0
;r
R r W 0 t mW 0 W 0 h0 h ;t ;Ca0 ;Re 0 ;a f ;h h0 h0 m h0 h0
Advanced Materials and Technologies Laboratory • University of Connecticut
Solution Approach: Perturbation Analysis * 0* 1* O( 2 ) p* p*0 p1* O( 2 ) Substituting the power series expansions into the nondimensional form of the governing equations and associated conditions, and collecting terms of the first two powers of the perturbation parameter— the wave number, — yields two differential equations for the two unknowns * and p*. Substituting these into the kinematic condition and defining a nondimensional coating thickness: (t*,z*) = h*(t*,z*) – 1 yields a partial differential equation for , whose solution is of the form: d ZW i 0 cosZ dr t ; V f
Ai exp
Z z
Vf t W0
dr : the dimensionless linear wave speed di : dim ensionless growth rate of the amplitude
Amplitude of the thickness variation at the entrance to the cure region (Zf) = coating thickness in the final product d Z W i f 0 A f Ai exp V f
Ai is still unknown
Advanced Materials and Technologies Laboratory • University of Connecticut
Initial Perturbation Amplitude Correlation Ai = f(Re, S, pin/pa, Rd/Rf. L/Rf) Re
V f R f : Re ynolds Number m
Rd R f : Radius Ratio
L R f : Aspect Ratio
pin pa : Inlet Pr essure Ratio
OhCa S
2
Fr
gm 4
3
Ai C1 Rd R f L R f pin pa S n 4 exp S n 5Re n 6 f1 exp f 2 Re n 6 n1
n2
n3
Using experimental data from Panoliaskos, et al., (1985), Wagatsuma, et al., (1986) and Kobayashi, et al., (1991), the coefficients and exponents are determined empirically to get
Ai 0.079Rd R f
1.5
L R f
0.5
pin
pa
3.85
S 0.1023 exp S 0.964 Re 3
Advanced Materials and Technologies Laboratory • University of Connecticut
Effects of Process and Geometry on Final Amplitude
Advanced Materials and Technologies Laboratory • University of Connecticut
Design of Process Parameters & Applicator Geometry
The maximum Reynolds number decreases with increasing S or decreasing inlet pressure ratio The maximum Reynolds number increases with increasing Rd/Rf or L/Rf
Advanced Materials and Technologies Laboratory • University of Connecticut
Remarks
Linear Perturbation Analysis was applied to the study of coating thickness fluctuation in optical fiber manufacturing. Effects of S, Re, pin/pa, Rd/Rf and L/Rf on the coating thickness variation were presented. Process parameters have a more pronounced influence on the fluctuation than the geometric parameters. Af increases with increase in Re or S, and with decrease in pin/pa, Rd/Rf or L/Rf. A methodology for identifying design and process parameters based on maximum allowable thickness fluctuation was presented.
Advanced Materials and Technologies Laboratory • University of Connecticut
Outline
Introduction to Advanced Materials and Technologies Laboratory Optical Fiber Drawing Numerical Modeling Analysis of dopant concentration and refractive index profile evolution during manufacturing Simulation and optimization under uncertainty Analysis of coating thickness variations A sampling of other recent research activities in the Laboratory
Advanced Materials and Technologies Laboratory • University of Connecticut
Composites Processing
Flow Control in Liquid Composite Molding The Process
The Problems Vacuum Line Vent
Resin Line Inlet
0.00
0-0.
The Approach
Processing-Interphase-Property Relationships AFOSR MEANS Program Tf tramp
Tj
[(CT)T ] T (kT T ) t y y
[ CT ] T (k )C EO HR (1v f ) t y y t
30 t'=10.80 t'=54.00
25
t'=0.11
0
20
t'=10.80
2.0
t'=54.00
1.8
40 60 Molecular Layer
80
100
1.2
5.0
Interphase
1.0 4.5
t'=147.18
1.6 1.4
di
0.5
Glass Fiber
2
Modulus, E [GPa]
pph PACM20
t'=147.18
20
y* = 0.0
t'=0.11
2.2
35
y/L 0.0
5.5
2.4
y* = 0.0
6.0
E , [GPa]
40
y
Matrix
di 0
10
20 30 Molecular Layer
40
4.0
0
50 100 150 Cure Cycle Ramp Time, t'
200
r
50
5.8 5.6
y/L 0.0
5.4
0.5
5.2 5.0
1.0
4.8 4.6 4.4 -0.1
0 0.1 0.2 0.3 0.4 0.5 Cure Cycle Hold Temperature, f
0.6
Thermoplastic Composites Processing Stage 1: PREPREGGING
Fiber Prepregging Matrix Prepreg
CONSOLIDATION
Advanced Materials and Technologies Laboratory • University of Connecticut
Thermoplastic Tape Laying/Tow Placement
Heat Transfer
(Temperature History)
Compaction
(Void Growth/Reduction)
Intimate Contact Polymer Healing Polymer Degradation Polymer Crystallization
(Strength Development)
(Mechanical Properties)
Advanced Materials and Technologies Laboratory • University of Connecticut
Placement Head
Compaction Force Main Heater
Preheater
Advanced Materials and Technologies Laboratory • University of Connecticut
Process Simulations and Processing Runs Polymer Crystallization
Polymer Degradation
Statistical DOE was carried out on the fabrication of 8� dia. rings using AS4/PEEK prepregs. Products evaluated in regard to interlaminar shear strength (short beam shear test), void fraction, and microstructural quality
Advanced Materials and Technologies Laboratory • University of Connecticut
Process Design Considerations
Objective
Maximize Interlaminar Bond Strength Constraints Void Content (at Roller 2 exit)
v vmax Dimensional Change (Degree of Compaction)
hi h f Dc hi
Dc,max
Polymer Degradation (of mass [and properties] due to prolonged exposure of polymer to high temperatures)
max
Advanced Materials and Technologies Laboratory • University of Connecticut
Parametric Effects 1
0.6
Degree of Bonding, D b
T 1 = 700 oC; T 2 = 800 oC
Void Fraction at Roller Exit [%]
N
2 4 6 8
0.8
0.6
10 25
0.4
0.2
0 0
10
20
30
40
50
60
70
0.5 0.4 0.3 0.2 0.1
T 1 = 700 oC; T 2 = 800 oC
0 0
80
N 2 4 6 8 10 25
10
Line Speed, V [mm/s]
40
50
60
70
80
0.01 N
N
0.15
T1 = 700oC ; T = 800oC 2
25 10 8
0.13
Degree of Degradation, ď Ą
Degree of Compaction, D c
30
Line Speed, V [mm/s]
0.17
0.11 6
0.09 0.07
4 2
0.05 0.03 0.01
20
0
10
20
30
40
50
60
Line Speed, V [mm/s]
70
80
T1 = 700oC; T2 = 800oC
25 0.008 10 0.006 8 0.004 6 0.002
0 10
4 2 15
20
Line Speed, V [mm/s]
25
Processing Windows T 1 = 600 oC; T 2 = 700 oC
Line Speed, V [mm/s]
100
V op tuc based on Max. Strength V m in based on Š 0.001 V based on v Š 0.2% m ax f V m in based on Dc Š 0.1
80
60 Optimum Line Speed B
40 Processing Window 20
D C A
0
1
5
9
13
17
21
25
Number of Layers T 1 = 600 oC; T 2 = 800 oC
100
T 1 = 600 oC; T 2 = 900 oC
100
V uc based on Max. Strength op t V m in based on Š 0.001 V based on v Š 0.2% m ax f V based on D Š 0.1
based on Max. Strength V based on Š 0.001 m in V based on D Š 0.1 m in c V based on v Š 0.2%
80
m ax
60
f
Optimum Line Speed B
40
Processing Window D
20
C
Line Speed, V [mm/s]
Line Speed, V [mm/s]
V uc op t
80
m in
c
Optimum Line Speed
60 B
Processing Window
40
D C
20 A
A
0
1
5
9
13
17
Number of Layers
21
25
0
1
5
9
13
17
Number of Layers
21
25
Product Quality
Advanced Materials and Technologies Laboratory • University of Connecticut
Fabrication of High Aspect Ratio Microstructures (HARMs)
Microcasting of Ceramic and Metallic Microparts Al2O3 Microgear
Fabrication of Ceramic and Metallic Microparts Slurry
Microchannel
Mold Top View
Micropart
Capillary-driven Mold Filling Microcast Slurry, (arrows indicate slurry flow) Cured and Planarized
Stainless Steel Microgear with nominally 8 mm teeth
Binder Removal/Sintering Demolded Composite Preform (Shrinkage)
Advanced Materials and Technologies Laboratory • University of Connecticut
Fuel Cells
Fuel Cell Performance and Related Issues Measured in terms of a Cell voltage – Current density variation, referred to as a
Cell Voltage, V
polarization curve.
Decreasing Ecell
Average Current Density, I
Local current density could be high and its spatial variation is a factor influencing membrane reliability; it is desirable to minimize the spatial variation.
A second issue pertains to the system complexity associated with balance of plant; it is desirable to reduce system complexity.
Advanced Materials and Technologies Laboratory • University of Connecticut
Planar PEM Micro Fuel Cell (µPEMFC) Traditional fuel cell designs are based on a ―sandwich‖ construction of stacking constituent layers; Micro and miniature fuel cell designs have also focused primarily on the layered design, while shrinking the size Proposed concept is that of combining microfabrication techniques with fuel cell technologies to achieve compact, modular, and scalable designs for high power density A unique feature of the mPEMFC design is that the cathode and the anode channels are patterned in a planer configuration. The design also eliminates gas diffusion layers; Design lends itself to fabrication of fuel cell arrays with associated circuitry on a single wafer
Advanced Materials and Technologies Laboratory • University of Connecticut
Fabrication of mPEMFC
1. Solution casting 40~50 mm Nafion® 500 mm Si Substrate
2. Hot pressing of microchannels Si Micro Die
Nafion® Si Substrate
3. Current collector deposition Au
Au mask
Top view of the cell
Substrate 4. Catalyst deposition Pt/C Catalyst mask Nafion
Substrate 5. Sealing with PDMS
PDMS H2
H+
O2
Substrate
Pattern Fidelity
mPEMFC Testing Cell dimensions: 25mm x 25mm x ~5mm Width of microchannels: 500mm 0.9
Single cell prototype Patterned Nafion® micro channels No gas diffusion layers H2 and air operation Concept also applicable to DMFC Active area ~0.33 mm2
80
0.8
Comparison with Peer Designs
70
0.7 60 0.6
V (V)
2
0.5
P (mW/cm )
50
40 0.4
V (V) P (mW/cm2)
30 0.3 20 0.2
10
0.1
0 0.00
42.67
85.33
128.00
218.66
0 253.33
I (m A/cm2 )
Advanced Materials and Technologies Laboratory • University of Connecticut
mPEMFC Arrays and Interdigitated Stacks
Parallel stack of 7 mPEMFCs
Series-parallel stack of 21 mPEMFCs
Advanced Materials and Technologies Laboratory • University of Connecticut
Acknowledgments Funding National Science Foundation Office of Naval Research Army Research Office Air Force Office of Scientific Research
Sandia National Laboratories Students and Collaborators C. Acquah, Q. Jiang, Dr. A. Mawardi, Dr. F. Yang, Dr. R.J. Johnson, B. Elolampi, Dr. A. Morales (Sandia)
Thank you! Advanced Materials and Technologies Laboratory • University of Connecticut
Functionally Graded Material Designs
Advanced Materials and Technologies Laboratory • University of Connecticut
Air Breathing Fuel Cells/Prototype Hybrid Fuel Cell/Battery System
Stack Voltage, EStack [V]
15.0
35 30 25
10.0
20 15 5.0
10
0.0 0
1
Voltage (V) Power (W)
5
3
0 4
2
Power, P [W]
Design specifications: 25 W avg. power Power delivery at 12 VDC (regulated) Hydrogen fuel, and air-cooled Provide 1800 Wh of energy over 72 hrs
T = 25 oC, RHa = 0 %, H2 Pressure=5 psi
Current, I [A]
Fuel Cell
10.00
Power (W) 25
12 VDC
8.00
20
Voltage (V)
6.00
15
4.00 10
2.00 5.0
Long Term Test Five units (10 fuel cells), room temperature, flow rate = 0.75lpm 0.00
0.0
0
10
20
30
40
50
Time (Hrs)
Advanced Materials and Technologies Laboratory • University of Connecticut
Power (W)
Voltage (V)
DC/DC Converter
30