Case Study: Heat Recovery with an
Ammonia Heat Pump
Kraft Foods
Don Stroud
Vilter Manufacturing LLC Emerson Climate Technologies
Sam Gladis
Kraft Foods - Oscar Mayer
Processing Facility
Davenport, Iowa
OVERVIEW • Project Definition
• Design Parameters
• System Description
• Actual Results
• Operation / Maintenance
• Recommendations and Conclusions
Project Definition
• Meat Processing Facility
• Refrigeration
• Conventional Industrial Ammonia
• Screw & Reciprocating Compressors
• Evaporative Condensers
• Heating
• Steam Boilers
• Stack Condensing Economizer
• Pre-heat Economizer
• Direct Contact Hot Water Heaters
Design Parameters
OBJECTIVE: Use an ammonia heat
pump to replace the use of a direct
contact water heater.
Design Parameters
OBJECTIVE: Use an ammonia heat
pump to replace the use of a direct
contact water heater.
Direct Contact Water Heater • Capacity = 7.013 MMBtu
• Average Flow Rate = 170 gpm
• Average Inlet Temperature = 62.5°F
• Outlet Temperature = 145°F
• Fuel: Natural Gas
• Efficiency: 97%
• Hourly Operating Cost = $50.61
Ammonia Heat Pump
Summer Capacity = 8.200 MMBtu
Flow Rate = 205 gpm
In/Out Temperatures = 65°F/145°F
Suction: 160 psig
Winter Capacity = 5.738 MMBtu
Flow Rate = 135 gpm
In/Out Temperatures = 60°F/145°F
Suction: 105 psig
Design Parameters
Ammonia Heat Pump
• Isolate the ammonia heat
exchangers from the potable water
• Monitor the performance with a
SCADA system, 29 points of data
Design Parameters
Ammonia Heat Pump
Summer 205 GPM, 65F to 145F 8,200 MBH/3.41 = 2,405kW
Suction = 160 psig, Condensing = 510 psig
Power = 594 HP/1.34 = 443kW
COP = 2,405/443 = 5.43
Winter 135 GPM, 60F to 145F
5,738 MBH/3.41 = 1,682kW
Suction = 105 psig, Condensing = 510 psig
Power = 562 HP/1.34 = 419kW
COP = 1,682/419 = 4.01
Average COP = 4.77 Average Hourly Operating Cost = $19.40
Design Parameters
System Description
• Refrigeration System
with Ammonia Heat Pump
• Hot Water System
with Ammonia Heat Pump
• Detailed Description
Ammonia Heat Pump
Compressors Condensers
Receiver
REFRIGERATION
Heat Pump
Hot Water Storage Tank
WATER HEATING
Direct Contact Hot Water Heater
(PRIMARY)
62°F
145°F
Hot Water Storage Tank
WATER HEATING
Direct Contact Hot Water Heater
(BACKUP)
62°F
145°F
Heat Pump
62°F
145°F
155°F
145°F
65°F
Heat Exchanger Inlet Temp
Outlet Temp
Heat (MBH)
%
Subcooler 75°F 85°F 1,025 12.5%
Desuperheater 85°F 89°F 410 5.0%
Oil Cooler 89°F 94°F 512 6.2%
Condenser 94°F 155°F 6,253 76.3%
TOTAL 75°F 155°F 8,200 100%
8,200 MBH TOTAL HEAT
Of REJECTION
Desuperheater
Oil Cooler
Subcooler
Condenser
155°F
94°F
Actual Results
Summer: 209.9 GPM , 68.4F to 145.4F
8,080.6 MBH/3.41 = 2,369.5 kW
Suction = 170.5 psig, Cond’g = 478.1 psig
Power = 364.0 kW
COP = 2,369.5/364.0 = 6.51
Winter: 125.7 GPM, 67.8F to 145.1F
4,857.6 MBH/3.41 = 1,423.6 kW
Suction = 110.4 psig, Cond’g = 462.7 psig
Power = 336.9 kW
COP = 1,423.6/336.9 = 4.23
Actual Results
4,857.6 MBH/3.41 = 1,423.6 kW
Power = 336.9 kW
COP = 1,423.6/336.9 = 4.23
Summer: Winter:
170.5 psig
478.1 psig
110.4 psig
462.7 psig
8,080.6 MBH/3.41 = 2,369.5 kW
Power = 364.0 kW
COP = 2,369.5/364.0 = 6.51
0
250
500
750
1,000
1,250
1,500
1,750
2,000
2,250
2,500
2,750En
erg
y (k
W)
160 PSIG Host System Condensing Pressure
(Heat Pump Suction Pressure)
Heating Energy
Heat Pump Water Heater
Use
ful
Use
ful
Pu
rch
ase
d
Pu
rch
ase
d
2,112 2,049 2,049
361
$0.00
$10.00
$20.00
$30.00
$40.00
$50.00
$60.00
160 PSIG Host System Condensing Pressure
(Heat Pump Suction Pressure)
Hourly Operating Costs and Savings
Energy costs based on $7.00 per MMBtu natural gas and $0.045 per kWh electricity
Heat Pump
Direct Contact Water Heater Savings
$16.26
$52.03
$35.77
Other Savings
• To the existing ammonia system
the heat pump performs as an
additional condenser
• With heat pump operating,
condensing pressure drops 3-5 psi
• 105 HP (78.3 kW) power reduction
• ≈ $15,000 savings (half year)
Other Savings
• To the existing ammonia system
the heat pump performs as an
additional condenser
• When condensing pressure is at
minimum 105 psig, the heat pump
offsets condenser fan & pump power
• 105 HP (78.3 kW) power reduction
• ≈ $15,000 savings (half year)
Other Savings
• To the existing ammonia system
the heat pump performs as an
additional condenser
• 7,000 MBH Condensing Capacity
• 4.8 GPM Water Savings per 100 tons
• 14 million gallons water saved/yr
• 2.4 GPM Water to Drain per 100 tons
• 7 million gallons sewage savings/yr
• Comparable water treatment savings
Operation & Maintenance
• Operation
• PHA Performed prior to install
• Risks evaluated and recommendations
applied to design
• Fully automated operation
• Minimal operator input required
• Maintenance
• No different than existing
refrigeration equipment
Recommendations and Conclusions
• Consider all hot water loads/uses
• Perform energy assessment
• Hot Water Load Profile
• Refrigeration Operating Conditions
and Load Profile
• Daily and Seasonal Weather Data
• Utility Costs
• Electric, energy & demand
• Fossil Fuel
• Water / Sewage
• Water Treatment & Softening Chemicals
• Heater/Boiler & Condenser Maintenance
Case Study: Heat Recovery with an
Ammonia Heat Pump
Thank You