european regional climate zone modeling of a commercial...
TRANSCRIPT
European Regional Climate Zone Modeling of a Commercial Absorption
Heat Pump Hot Water Heater
Vishaldeep Sharmaa, Bo Shena, Christopher Keinathb,Michael Garrabrantb, Patrick Geoghegana
aOak Ridge National LaboratoryOak Ridge, TN, USA
bStone Mountain Technologies, Inc.Johnson City, TN, USA
12th IEA Heat Pump ConferenceRotterdam Netherlands
15th – 18th May 2017
Outline
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v Introductionv Climate Zonesv Full Service Restaurant Configurationv GAHP Thermodynamic Modelv EnergyPlus Modelv Simulated Water Draw Patternv Resultsv Conclusions
Introduction
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v Commercial water heating accounts for approximately 0.78 Quads of primary energy (0.44 Quads from natural gas systems) in the US
v Commercial water heating accounted for 12.6 kW/m2 in Western Europe in 2010v Current gas water heating systems limited to COP < 1v The gas absorption heat pump (GAHP) offers COP > 1
SpaceHeating17%
Cooling7%
Ventilation6%
WaterHeating16%Lighting
10%
Cooking25%
Refrigeration16%
Other3%
FoodService(US)
buildingsdatabook.eren.doe.gov
Family of Absorption Heat Pumps, 3-40 kW
Introduction to GAHP
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v Offer COP values >> 1v Maintain heating performance at low ambients
v Single-effect ammonia-water absorption heat pumpv SHX & RHX effectiveness of 0.97 & 0.93v Evap-Amb pinch of 3°Cv CHX-Hyd pinch of 3°Cv HCA pinch of 3°Cv Condenser pinch of 10°C
v SE versus GAXv Lower desorber temps than GAX v Better reliability v More options for NC controlv Fewer heat exchangers/lower costv Easier to control and modulate
System Configurations
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Conventional High Efficiency Configuration
GAHP Configuration
Climate Zones & Cities Investigated
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v 10 European Cities v All 5 climate zones of Europe
City Zone Madrid 1&2 Rome 1&2 Athens 1&2
Moscow 3 Vienna 3 London 4
Paris 4 Oslo 5
Reykjavik 5 Helsinki 5
GAHP Thermodynamic Model
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Ambient Temperature Range, °C GAHP Performance Penalty Tamb > 3.5 No penalty
3.5> Tamb > -2.7 4% reduction -2.8 > Tamb > -9 3% reduction
-9 > Tamb No penalty
v Absorption heat pump model developed in Engineering Equation Solver (EES)
v Curve fits for use in EnergyPlus developed from modeling performance curvesv Performance penalties implemented to account for the defrost requirements at
certain operating conditions
EnergyPlus Model
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v Stratified modelv Air-source heat pumpv 1.7 W/m2-K skin loss coefficientv Six control volumes uniformly distributedv Heat Pump pulls water from the bottom and returns to the middle of the
tankv 1 minute time stepv Controlling sensor 1 meter from bottom of storage tank
Simulated Water Draw Pattern
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0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0 2 4 6 8 10 12 14 16 18 20 22 24
Waterdraw,kg/s
Time,hrs
Full service restaurant draw pattern based on work by Fisher and Pietrucha (2008)
v 7.95 m3 (7950 liters) of water drawn in 24 hour period
Results – Nominal day in London
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v Tank 1 inlet (mains water), tank 1 outlet and ambient temperature for nominal day of March 20th
GAHP Coupled Tank Temperatures
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v Tank 1 nodal water temperatures for nominal day of March 20th in London
Average Annual COP
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v Average GAHP configuration COP of 1.4 v Average high efficiency configuration COP of 0.92
v It should be noted that ALL of the reported COP values use the Higher Heating Value (HHV) in the evaluation of the Natural Gas energy input
Annual Gas Usage
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v 525 GJ/year and 691 GJ/year for the conventional high efficiency systemv 342 GJ/year and 495 GJ/year for the GAHP system
Conventional High Efficiency Configuration
GAHP Configuration
Annual Gas Savings
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v Annual fuel savings determined for each cityv On average, GAHP offered an annual gas savings of 31%
Climate Zone Location Annual Percentage Gas Savings (%) London 31 Athens 35 Oslo 29
Moscow 29 Madrid 33
Reykjavik 28 Paris 32
Vienna 31 Rome 34
Helsinki 29
Payback
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v Assumed GAHP installed cost of 17300 eurosv Assumed standard high efficiency installed case of 10600 eurosv In the first half of 2016, natural gas prices for industrial consumers were on
average 0.033 euros/kWh (lowest in 6 years)
Conclusions
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v Use of GAHP in full service restaurant in 10 European cities in all 5 climate zones were investigated
v Average annual COP of GAHP and high efficiency conventional system were 1.4 and 0.92 respectively
v GAHP offers an average annual gas savings of 31% over a high efficiency system utilizing a condensing gas water heater
v The GAHP offers a payback of ~ 4 years at 0.033 euros/kWh
v Payback strong function of natural gas price
Future and Ongoing Work
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v Modeling study will be expanded to the cold climate regions within the United States
v Commercial water heating field test of a 41 kW GAHP (application to be TBD)
v Commercial water heat field test of two 23.5 kW GAHPs (application full service restaurants)
Acknowledgements
19
Thank You
Michael Garrabrant, PEPresident & CEO
Stone Mountain Technologies, Inc. Johnson City, TN, USA
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