ceramic/metallic heat exchanger development
TRANSCRIPT
Ceramic/Metallic Heat Exchanger Development
9th Annual SECA WorkshopPittsburgh, PA.August 7, 2008
Anthony F. Litka
Project Objective
Combine ceramic and metallic heat exchanger cores to produce a low cost, high effectiveness, recuperator for cathode air preheating
Hybrid Recuperator Advantages
M etallicAdvantages
• M anufacturability• Extended Surface• Compactness• Therm al Shock
Disadvantages
• H igh Cost• Fouling/O xidation
C eram ic
Advantages
• Low Cost M aterials• H igh Tem p Stability• Single Casting
Disadvantages
• Therm al Shock
H ybridAdvantages
• Low Cost M aterials Throughout• M odular M anufacture• Temperature G radients on Ceram ic are R educed• M aterials O ptimized for Temperature• Therm al Expansion Unrestrained
Recuperator Specification
• Exhaust Inlet Temperature – 850 – 950 C• Air Outlet Temperature – 725 - 800 C• Effectiveness – >85%• Total Pressure Drop – 1250 Pa• Equal Air and Exhaust Flowrates• Air Flow – 150 lpm per kWe
Initial Generator Configuration
Cathode Air Path
Burner
Exhaust
SOFC Stacks
Cathode Blower
Recuperator
Cathode Air Path
Burner
Exhaust
SOFC Stacks
Cathode Blower
Recuperator
Cross Flow Metallic Recuperator
CathodeAir InHot Air
Out
ExhaustIn
ExhaustOut
CeramicCore
MetallicCores
CathodeAir InHot Air
Out
ExhaustIn
ExhaustOut
CeramicCore
MetallicCores
Cross Flow Hybrid Recuperator Concept
Ceramic Core
Manufactured by Blasch Precision Ceramics , Albany NY
Cross Flow Configuration
3 Pass Cross Flow Hybrid Performance
Metallic Core Effectiveness = 77.3%
Metallic CoreEffectiveness = 77%
Ceramic CoreEffectiveness = 37.7%
Air Inlet
Air Outlet
Exhaust Inlet
Exhaust Outlet
T = 417 C
T = 641 C T = 708 C
T = 532 C
T = 845 C
T = 25 C
T = 718 C
Flow = 70.9 kg/hr
Flow = 67 kg/hr Overall Effectiveness = 85%
2 Pass Cross Flow Hybrid Performance
Metallic Core Effectiveness = 78.7%
Ceramic CoreEffectiveness = 47%
Air Inlet
Air Outlet
Exhaust Inlet
Exhaust Outlet
T = 538 C
T = 850 C
T = 677 C
T = 23.5 C
T = 684 C
Flow = 70.9 kg/hr
Flow = 70.9 kg/hr
Overall Effectiveness = 80%
Stack Size Reduction
Cathode Air Downcomer
Offgas Injectors
Fuel Plenum
Offgas Plenum
Cathode Air Distribution Region
CatyliticOxidation Tile
Cathode Air to and from Recuperator
Anode Gas Inlet
Cathode Air Downcomer
Offgas Injectors
Fuel Plenum
Offgas Plenum
Cathode Air Distribution Region
CatyliticOxidation Tile
Cathode Air to and from Recuperator
Anode Gas Inlet
Axial Flow Stack Geometry
Counter Flow Recuperator
Startup Burner
Exhaust Plenum
Air OutletPlenum
Stack Chamber(cells not shown)
Hot AirDuct to StackBottom
Air InletPlenumAir (tube side)
Exhaust (shell side)
Counterflow Fin Core Recuperator
Counter Flow Hybrid Recuperator
Recuperator Assembly
Ceramic Monolith
Fin Core Hybrid Cross/Ctr Flow
Ceramic Core Performance
500
550
600
650
700
750
800
850
350 400 450 500 550 600 650 700 750 800 850
Ceramic Air Inlet Temperature (C)
Cer
amic
Air
Out
let T
empe
ratu
re (C
)
Exhaust Inlet Temperature = 830 CAir & Exhaust Flow = 200 lpm
Model Prediction(Baseline)
Model Prediction(Reduced Channel Width)
Folded Sheet Recuperator
Folded Sht Hybrid Performance Gain
Air Flowlpm Metallic Hybrid100 0.71 0.787200 0.705 0.816300 0.698 0.780
Ovl Effectiveness
Cross/Ctr HX Performance
0
10
20
30
40
50
60
70
80
90
100
350 450 550 650 750 850 950Exhaust Inlet Temp (C)
Air
Tem
pera
ture
Del
ta C
eram
ic (C
)
100 LPM
200 LPM
300 LPM
Future Activities
• Complete performance testing• Conduct both long term and thermal cycle
testing• Evaluate techniques to optimize ceramic
core heat transfer – more passages, fins• Evaluate and demonstrate heat exchanger
geometry to larger sizes