Collaboration for aquaponics sustainable Energy: Case
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Transcript Collaboration for aquaponics sustainable Energy: Case
Design and Modeling of Combined Heat and
Power Systems for Sustainable Urban
Agriculture and Aquaculture
Team Members:
Ben Steffes
Dan Neumann
Brandon Jackson
Nate Weber
Chris Chapman
Faculty Advisor:
Dr. Chris Damm
Milwaukee School of Engineering
AQUAPONICS OVERVIEW
Borrowed from:
http://www.photosbysc.com/Aquaponics/Saras_Aquaponic_Blog/Entries/2008/4/13_What_is_Aquaponics_files/droppedImage_1.png
CHP OVERVIEW
CHP Combined Heat and Power
One fuel source for multiple types of output power
Electricity
Thermal Energy
High overall efficiency
Fuel
Thermal
CHP System
Electrical
Develop models to guide in the development of an
advanced energy system for aquaponics
System level design of an environmentally responsible
and economical system capable of reducing carbon
emissions through higher efficiency
Create a simulation tool to aid in the designing and
selection of aquaponics energy systems
Greenhouse Environment between 45-60% relative
humidity and 55°F-85°F
Rearing Tank sizes ranging from 1,000-20,000 gallons
Maintain Tank Temperature Between 75°F-85°F
Consider both natural and artificial lighting
DESIGN CONSTRAINTS: POWER PRODUCTION
Provide power to aerate, heat, and pump tank water
Provide power for artificial lighting
Operate on Natural Gas
Continuous Operation With Exception for Maintenance
Less CO2 emissions than Milwaukee Emission Statistic
Lowest Cost/Least Environmental Impact
INITIAL PLANS
Mechanical
Natural
Gas Engine with Heat Exchangers
Supply
mechanical demand for:
Pumps
Blowers
Heat
exchangers to Provide heat for aquaponics tank(s)
Electrical
Commercial
Supply
CHP generator set
electricity for:
Pumps
Lighting
Provide
heat for aquaponics tank(s)
ELECTRICAL VS. MECHANICAL
Engine Trouble
Introducing lubrication (2-stroke)
Maintenance cycle
Space requirements
Efficiency of Heat Exchangers
MOVING FORWARD WITH ELECTRICAL SYSTEM
Took system level approach to pairing CHP and
aquaponics using commercially available CHP generators
Selected Marathon ecopower
Borrowed from: mathonengine.com
MARATHON ECOPOWER
Estimated installed system cost approximately $35,000
4000 hour maintenance interval
Specifications
Electrical Power
Thermal Power with max. flow
temp. 167 °F [75 °C]
Overall Efficiency
Engine
Exhaust Gas Figures [at 5% O2]
Grid Feed [Single Phase]
Sound Level
Dimensions/ Weight
Approvals
2.0 – 4.7 kW
6.0 – 12.5 kW
>90% (approx. 25% electrical + approx 65% thermal)
Single-Cylinder, 270 cm3, 1,700 – 3,600 rpm
NOx < 1.98 mg/ft3 CO < 11.33 mg/ft3 Temp < 194 °F [90 °C]
250 VAC, 50/60 Hz, Power Factor = 1
< 56 dB [A]
54 in. L x 30 in D x 43 H 858 lb
CE – Certificate, ETL - Approved
THERMAL MODELING
qevap , surf
Atmosphere
Ta , pa , P
qconv , surf
Water Level
Tw , hw , pw
Ground
Tg
qconv , wall
qcond ,base
CHP system sized for thermal load
Point of most efficient operation
Model used to approximate thermal loading
Surface convection and evaporation, wall convection, base
conduction, and hydroponic tank losses
Evaporation (Two Models)
(R.V. Dunkle 1961) Based on model of distillation pond
evaporation
p pa
q e 0.0254 T w T a w
T
460
a
39
p
a
1 3
pw
p a hw
(W.S. Carrier 1918) Empirical model based on indoor swimming
pools
98.7 0.43V
G 0.491
pw pa
h fg
Surface Convection
Related to surface evaporation (I.S. Bowen 1926)
Tw Ta P
0.004943
qe
p
p
14.7
a
w
qc
Wall Convection
Based on non-dimensionalized analysis of flat plate
convection
N u L 0.13 G rL P r
Nu L hL k
1/ 3
G rL g L T
2
3
Pr C p k
Hydroponics Tank Losses
q&g ro w b ed m&g ro w b ed c p , w a ter T tan k T retu rn
2
PSYCHROMETRIC CHAMBER TESTING
Tank water temperature (F)
Atmospheric temperature (F)
Relative humidity (%)
Total run time (min)
Trial 1
~72
50
50
100
Trial 2
70
60
31
210
Temperature [F]
System Temperatures
80
Water
Atmospheric
60
40
0
0.5
1
1.5
2
2.5
3
3.5
2.5
3
3.5
Heater Power [BTU/hr]
Humidity [%]
System Relative Humidity
0.35
0.3
0.25
0
0.5
1
1.5
2
System Input Power
400
Raw Power Input
Averaged Power Input
200
0
0
0.5
1
1.5
2
Time [hr]
2.5
3
3.5
Evaporation Rate Over Time
0.12
Evaporation [lbm/hr]
0.1
0.08
0.06
0.04
0.02
0
0
R.V. Dunkle
W.H. Carrier
Actual Mass Loss
0.5
1
1.5
2
Time [hr]
2.5
3
3.5
q&conv , surf q&in q&evap q&conv , w all m c p , w ater
dT w ater
dt
System Energy
200
150
Energy [BTU/hr]
100
50
0
-50
Surface Evaporation (Predicted)
Surface Evaporation (Actual)
Heater Power (Actual)
Surface Convection (Actual)
Surface Convection (Predicted)
Water Transient
Tank Wall Convection (Predicted)
-100
-150
-200
0
0.5
1
1.5
2
Time [hr]
2.5
3
3.5
THERMAL LOAD PROFILE
Property
Tank Temperature
Greenhouse
temperature
Relative Humidity
Flow Rate
Value
80
70
Units
F
F
50
67
F
GPM
Return Temperature 78
Tank Size
7 width
3.5 height
30 length
Number of Tanks
Rubber Liner
Lumber
R7 Foam Insulation
2
0.25
1.5
1.5
Thermal Losses For Aquaponics
System
Surface Evaporation
Tank Wall Convection
Base Conduction
0%
F
Ft
Inch
Inch
Inch
Surface Convection
Gardening Losses
16%
81%
2%
1%
AQUAPONIC SYSTEM PROPORTIONING
University of Virgin Islands (UVI)
Raft
Style Commercial System
Proportioning Hydroponic Tank to Rearing Tank
Hydraulic
Loading Rate
Retention Time
Feed Rate
POWER REQUIREMENTS
Pumping
Centrifugal Pump
Rearing Tank Aeration
Greater Stocking Density
Regenerative Blower
45% Efficiency (elec.-water)
64% Efficiency (elec.-water)
Artificial Lighting
Implemented in few cases
18 Hr daylight grow period
Faster Plant Growth
V olum etric Flow *P ressure D ifference
E lectrical P ow er
POWER CALCULATION METHODS
SYSTEM HEAT & POWER REQUIREMENTS
SIZED SYSTEM FOR MARATHON ECOPOWER
(11000 GALLON)
System Calculated Power:
Pumping: 0.64 Hp (460 W)
Aeration: 1.44 Hp (1.06 kW)
Lighting: 43.8 Hp (32.7 kW)
Thermal: 39000 Btu/hr (11.43 kW)
UNIVERSITY OF VIRGIN ISLANDS SYSTEM
USING DEVELOPED PROCEDURE (8240 GALLON)
Calculated Power:
Pumping: 0.50 Hp (370 W)
Aeration: 1.1 Hp (800 W)
Lighting: None
Thermal: None
UVI System:
Pumping: 0.50 Hp
Fish Tank Aeration: 1.5 Hp
RESULTS OF ECONOMIC ANALYSIS
Conditions:
$35,000 installed system
cost
Analysis uses current
utility pricing
CHP system run using
thermal load following
Net metering 1:1
Replaces 75% efficient
natural gas water heater
Results:
31,000 kWh Electricity
Generated Annually
83,000 kWh Water Heating
Using 462,000 cu.ft
natural gas ($4,300)
$3,000 Annual Benefit
12 year simple payback
10 year payback with 3%
inflation
No incentives applied
RESULTS OF ENVIRONMENTAL ANALYSIS
Results:
16.4 tCO2 avoided annually based on
Milwaukee emissions profile
14.5 tCO2 avoided annually based on National
emissions profile
Equivalent to approximately 2.8 cars and light
trucks not used
20.4 MPG
11,720 Miles
To provide a selection tool to farmers to assist in
incorporating CHP into efficient aquaponics operations
QUESTIONS