Novel
Energy
Systems
for
Distributed
and
Mobile
Power
Genera;on
William E. Lear
University of Florida
Department of Mechanical & Aerospace Engineering
Gainesville, FL
UF Energy & Gas
Dynamics Laboratory
May 23, 2011
Univ. Stellenbosch
Outline
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Semi-closed cycle description
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Use in distributed generation
System benefits and challenges
Analytical and experimental results
Discussion and Conclusions
DMFC introduction and system description
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May 23, 2011
Advanced architecture
Application focus
Status and challenges
Univ. Stellenbosch
What Do We Want from a
Power System?
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Efficiency, compactness, low cost…
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We really want a “best friend”
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Helps you be comfortable
Doesn’t intrude on your space
Anticipates your needs
Is there when the chips are down
Doesn’t ask for money
May 23, 2011
Univ. Stellenbosch
How Does Current System Do?
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Comfort from major appliances
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Need electricity from grid, gas from pipe, water from pipe
Disruptions unless all distribution systems work - vulnerable
Intrudes on our space a little
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Emissions
Transmission lines
Geopolitics (non-renewable fuels)
Local maintenance
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Anticipates needs well - except transmission lines
 Displays character flaws when chips are down
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Hurricanes
Homeland security
Sneaky expensive
May 23, 2011
Univ. Stellenbosch
Disaster Infrastructure?
May 23, 2011
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May 23, 2011
Univ. Stellenbosch
Distributed Energy
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Smaller engines
installed near loads
CCHP - local cooling,
heating, power
Efficiency not bad
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Include cooling (how?)
Local transmission,
robustness, process
heat/cooling
Disadvantages: Cost, space, noise (esp.
Diesel), maintenance…don’t run continuously
May 23, 2011
Univ. Stellenbosch
Waste Heat Cooling Potential


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How cold can State 2 be?
Ideal gas, reversible
process, isobaric, zero
work
1st & 2nd Laws, Gibbs
eqn:
Q& = m& (h2 ' h1 )
Q&
( m& ( s2 ' s1 )
To
1
2
Q&
To

& T2 #
s2 ' s1 = C p ln$$ !!
% T1 "
May 23, 2011
HX + ?
Univ. Stellenbosch
Result:
' T2 $
ln%% ""
T1 #
T1
&
=
T2
To
!1
T1
Cooling Potential Results
VARS Cooling Potential
VARS Cooling Potential, ISO
1.2
100
50
0.8
T2/T1
0.6
T2/To
0.4
0.2
Exit T, F
Normalized Exit T
1
0
-50
-100
-150
-200
-250
-300
Exit T, F
-350
-400
0
0
1
2
3
4
0
1000
Inlet T, F
Inlet/Ambient T Ratio
May 23, 2011
500
Univ. Stellenbosch
1500
Gas Turbine Recuperation
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Low pressure ratio
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Typically small
engines
Centrifugal
compressor, but not
necessarily
p
4
T
Flat efficiency curve
Desire high
combustor inlet T
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T ds = δQ
High T gives small ds
High p ratio
unnecessary
May 23, 2011
Univ. Stellenbosch
p
3
5
2
6
1
s
Power, Water Extraction and
Refrigeration (PoWER) System
9.3
1w
VARS
CGC
HGC
Refrigeration
9.2
4w
10
Water Harvesting
3w
Y
PCW
AIR
14
15
3.1
1
MAI
2w
9.1
WGC
ReV
PCW
REC
2
Turbocharger
6
12
FUEL
C
13
4
LPT
LPC
AIR
3
HPC
HPT
5
18
Power
Microturbine Block
May 23, 2011
11
7
ExV
Univ. Stellenbosch
8
9
HPRTE Advantages
•
•
•
•
•
•
Increased efficiency/high part-load efficiency
• “Inlet” temperature low
Increased specific power and compactness
Ultra-low emissions
Low intake filtration, exhaust handling
Small lapse rate with temperature
Water extraction (mostly with VARS)
• Load leveling
• Emergency drinking water
• Ice
• Couple to steam gasification
May 23, 2011
Univ. Stellenbosch
System Benefits of PoWER
Distributed Energy
•
Complete local service
• Power, refrigeration, fresh water, heat
• Normal mode:
•
•
•
•
•
Emergency mode:
•
•
•
•
AC load, use water for peaking
Design for max efficiency or AC/power blend
Controlled by utility to follow loads
Efficiency & emissions warrant high usage
Local loads met, decreasing widespread impact
Switch to icemaking
Compactness, decreased siting requirements
Life-cycle costs competitive
May 23, 2011
Univ. Stellenbosch
Flameless Combustion
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Multiple Definitions in literature
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Implementation
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Absence of broadband luminosity
Reaction zone uniformity
Low heating value fuel
Dilute fuel with products (cooled)
Dilute oxidizer stream
Advantages
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Low emissions
Fuel flexibility
May 23, 2011
Univ. Stellenbosch
Flameless Combustion
O2
Conventional
Flamelet
O2
Spray Combustion
Flameless
Uniform Rxn
May 23, 2011
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Fuel Flexibility/Emissions
 Flameless combustion regime
• Low luminosity (neglegible soot)
• Flame uniformity
 Flame chemistry
• Damkohler number order unity
• Oxidation reaction distributed
• Limited pyrolysis due to oxidation
radicals
May 23, 2011
Univ. Stellenbosch
High Recirculation Combustion Facility
PoWER System (…Continued)
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Semi-Closed Cycle Engines and Flameless
Combustion
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More Uniform Combustor Conditions
Flatter Efficiency Profiles
Fuel Flexibility
Lower Flame Temperatures
Lower NOx Emissions
Lower Flame Luminosities
Suitable for distributed energy systems
May 23, 2011
Univ. Stellenbosch
Part-Power Efficiency
9
8
T2
10
1
C1
3.1
2
3.2
C2
4
5
T1
cm
6
7
R
5r 4r
Evaporator
IC1
2.9
Water
Harvesting
3
•Design-point efficiency comparable to or
better than conventional recuperated engine
2r
Ambient
Cooling
6r 1r
Generator
•Throttling to part-power via turbo wastegate or
variable geometry
•Leaves core engine at design point over most
of power band
May 23, 2011
Univ. Stellenbosch
3.0
2r
3r
•Issues include sensitivity to intercooler
effectiveness and pressure drop
Generator
2.9
1r
6r
Condenser
Expansion
Valve
Regulating
Valve
4r
Pump
7r
8r
Evaporator
Absorber
5r
3.2
3.1
Cooling
Loads
Ambient
Cooling
Life-Cycle Costs
Our studies (MS thesis) show cost advantage over conventional
microturbine for distributed generation
Boost of 4:1 increases power density of high temperature components
by an order of magnitude
Additional components (turbo, HX) relatively inexpensive
Part-load efficiency advantage reduces fuel costs
Result: Several percent cost savings typical
May 23, 2011
Univ. Stellenbosch
Demonstration Plant
May 23, 2011
Univ. Stellenbosch
PoWER Demonstrator
May 23, 2011
Univ. Stellenbosch
Potential Applications
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Stationary vs Transportation
Military vs Civilian
Combined Cycle vs Simple Cycle
Focus: stationary, small, distributed
generation, multi-fuel, dual-use
May 23, 2011
Univ. Stellenbosch