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8/10/2019 Harrison Solar Cooling IEA Australia 2013
1/23
EVALUATION OF A LIQUID
DESICCANT AIR CONDITIONINGSYSTEM WITH SOLAR THERMAL
REGENERATION
Stephen J. Harrison, Ph.D., P.Eng.
Solar Calorimetry Laboratory
Queens University
Kingston, Canada
8/10/2019 Harrison Solar Cooling IEA Australia 2013
2/23
Overview
Main focus of Canadian government is
combined heating and cooling systems Liquid Desiccant systems are being primarily
evaluated
Two LD systems: AIL LD prototype system andan Advantix DuCool air conditioning &
dehumidification.
Other systems operating in Canada, e.g.,
conventional absorption (EnerWorks) and largescale ClimateWell system.
8/10/2019 Harrison Solar Cooling IEA Australia 2013
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Project Overview
Liquid desiccant air conditioning (LDAC) demonstration project Phase I (completed):
Used gas fired boiler to simulate solar input and drive LDAC
Characterized and modelled LDAC performance
Phase II (in progress):
Installed evacuated tube solar array to drive LDAC
Will test different configurations and compare with simulation
results
Phase III (beginning)
Investigate methods to increase electrical COP Investigate additional desiccant storage
Investigate optimal configurations and control schemes
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
8/10/2019 Harrison Solar Cooling IEA Australia 2013
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EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
Solar availability matchedclosely with cooling load
LDAC applicable in Dedicated
Outdoor Air System (DOAS)
Designed to handle latent load Pair with evaporative cooler or
small vapour compression
system to handle sensible load
Ensure adequatedehumidification and provide
better control over humidity
0
2
46
8
10
12
14
16
VentilationLoadIndex
(kWh/m3/hr)
Sensible Cooling
Latent Cooling
Background
8/10/2019 Harrison Solar Cooling IEA Australia 2013
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Source: Lowenstein, A., Slayzak, S, and Kozubal, E. (2007). "A Zero Carryover Liquid-Desiccant Air Conditioner for Solar Applications," 2006 International
Solar Energy Conference, ISEC2006, American Society of Mechanical Engineers, pp. 397-407.
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
Conditioner
Strong desiccant absorbs moisturefrom process air
Cooling water removes latent heat of
condensation
Regenerator Heating water added to re-concentrate
desiccant
Moisture in dilute desiccant desorbed
to scavenging air stream
Novel low flow configurationeliminates carry over, increases
storage capacity
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EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
LDAC Benefits
Dehumidification without
over-cool reheat
Low temp (60-90C) heat for
regeneration, ideal for solar Loss-less energy storage
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8/10/2019 Harrison Solar Cooling IEA Australia 2013
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System OperationSystem Parameter Results
Process Air Flow 1200 L/s
Hot Water Flow 90 L/min
Cold Water Flow 130 L/min
Desiccant Concentration25.64-42.73
wt%
Conditioner Desiccant Flow 5.3 L/minRegenerator Desiccant Flow 6.5 L/min
Regeneration Thermal COP 0.4190.761
Heating Water Temperature 50 - 90C
Measured Latent Cooling
Capacity
4.523.3 kW
(1.36.6 tons)
Measured Total Cooling
Capacity
4.818.1 kW
(1.45.1 tons)
Cooling
Tower
Process Air
Outlet
Conditioner Air
Inlet
Regenerator
Air Inlet
Scavenging
Air Outlet
Heating Water
Piping
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
8/10/2019 Harrison Solar Cooling IEA Australia 2013
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EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
Boiler
LiquidDesiccant
Air
Handling
Unit
Cooling Tower
P4
Cooling Water
Heating Water
Buffer
Storage
P2
P1
Ball Valve
PumpEvacuated Tube
Solar Collectors
Non-standard Operation
Dry Cooler
P3
Solenoid Valve
Parameter Design ValueDesign Temperature Rise 10C
Total Collector flow rate 40-50 L/min
Collector Absorber Area 61m2
Buffer Storage Size 870L
Pumping Power (collector circulator) 25-450W
Dry Cooler Rated Capacity 56.5kW
Solar Array Description
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EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
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EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
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EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
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EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
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EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
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EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
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System Performance, Characterization and
Modelling TRaNsient SYstem Simulation program (TRNSYS)
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
8/10/2019 Harrison Solar Cooling IEA Australia 2013
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inheat
Cooling
TQ
QCOP
,
Thermal COP
inelec
Cooling
EW
QCOP
,
Electrical COP
inheat
DesorptionR
QQCOP
,
Regenerator COP
Collector Efficiency
Tcoll
p
IA
TcmColl
.
Solar Fraction
load
aux
Q
QSF 1
LDAC Performance
Solar Performance
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
8/10/2019 Harrison Solar Cooling IEA Australia 2013
18/23
Simulation Results
TRNSYS simulations
used to size array
Large array increases
cost, time in stagnation,pumping power
Sized for 65% solar
Storage
implementation toincrease SF and
utilization
0
0.1
0.2
0.3
0.4
0.5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 20 40 60 80 100 120
Percentage
ofTimeinStagnation
SolarFraction
Collector Absorber Area (m2)
Solar Fraction
Collector Stagnation
Design point
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
8/10/2019 Harrison Solar Cooling IEA Australia 2013
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Performance predicted for series (top) and parallel
(bottom) boiler configurations
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
8/10/2019 Harrison Solar Cooling IEA Australia 2013
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Boiler setpoint temperature important system parameter
Increases cooling capacity and LDAC performance
Decreases collector efficiency
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
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Conclusions
Installation of 95m2
evacuated tube solar array for low flowLDAC demonstration project
TRNSYS simulations predict
65% solar fraction
65% collector efficiencybased on absorber area
(41% gross area)
Typical LDAC COPT 0.4-.52
Average LDAC latent coolingpower between 13 and
23kW (3.8-6.6 tons)
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
8/10/2019 Harrison Solar Cooling IEA Australia 2013
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Future Work
Improve system by replacing inefficient fans and pumps andintegrating variable speed pump control
Implement desiccant storage in demonstration project, use
modelling to determine optimal storage configurations
Monitor array to determine capacity for space heating andevaluate potential for solar combi-system
0
1000
2000
3000
4000
Energy[
kWh]
Space Heating Load
Domestic Hot Water Load
Cooling Potential
Global Radiation on Collector
Solar Energy to Load, Qsol
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION
O O Q S CC CO O G S S SO
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Natural ResourcesCanada
Solar Buildings
Research Network
Queens University
Mechanical Engineering
AIL Research
EVALUATION OF A LIQUID DESICCANT AIR CONDITIONING SYSTEM WITH SOLAR
THERMAL REGENERATION