Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 1
COOLING, DEHUMIDIFICATION AND
AIR CONDITIONING POWERED BY
SOLAR / LOW GRADE HEAT
Gershon Grossman
Faculty of Mechanical Engineering
Technion, Israel Institute of Technology
Haifa 32000, ISRAEL
Seminar at the Weizmann Institute, 17 February 2013
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 2
Demand for Air Conditioning in the
World is on the rise…
• Climate change and Global Warming
• Increased standard of living + comfort
• A/C essential in modern business • European countries with no A/C tradition:
– Air conditioned space increased from in 30M m2 in 1980 to 150M m2 in
2000
– Number of A/C systems larger than 12 kW increased X5 in last 20
years
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 3
Demand for A/C associated with
increased demand for primary energy…
• AC – largest consumer of Electric power; In Israel - 30% of electric power produced is used for A/C
• Highest demand caused by business sector
• Electric utilities faced with peak demands in
hot summer months…
• Solar Cooling can alleviate the problem
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 4
Solar Cooling System
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 5
Solar Cooling/ Air Conditioning
TA TH
QH
QL QA1
QA2
TA TL
Heat
Engine
Heat
Pump
W
• Heat Pump driven by
Heat Engine
• Absorption/Adsorption
Heat Pump
• Closed-cycle systems:
Absorption, Adsorption,
Jet-cooling….
• Open-cycle systems:
Liquid desiccant, Solid
sorption
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 6
Chemical Heat Pump Principle
NH3
H2O
+NH3 NH3
H2O
+NH3
Tpure = Tsolution
Ppure > Psolution
Tpure < Tsolution
Ppure = Psolution
Tsolution-Tpure=Temperature Lift
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 7
Absorption Heat Pump Principle
Desorber
Absorber
QM2
QH
Evaporator
Condenser
Comp
QL
QM1
W
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 8
Single-Effect LiBr-H2O Absorption Chiller
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 9
Prototype 50 TR (175 kW) Solar
Absorption Cooling System, Tadiran ASD
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 10
Tadiran ASD Solar Cooling Project
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 11
200 TR (700 kW) Solar Absorption Cooling
System at Tel-Hashomer Hospital, Israel
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 12
Absorption Systems –
first cooling machines in History
• Chemical Heat Pumps – as early as 18th century
• First continuously operating refrigerators – Edmond and
Ferdinand Carrè ~1860
• Gas-fired NH3-H2O domestic refrigerators up till ww2
• Large-scale H2O-LiBr chillers powered by waste heat and
solar
• Multi-effect gas-fired chillers for A/C ~1980’s and on
• Domestic NH3-H2O heat pump development
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 13
Absorption Multi-Staging
• Staging required
to benefit from hi-
temp heat source
• Double-effect
chillers: Series
and parallel
connections
•Triple-effect
systems
•Cascading
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 14
Multi-Staging allows improved performance
with high heat source temperatures
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
50 100 150 200 250
Heat Supply Temperature (oC)
CO
P
Carnot
1-effect
2-effect
3-effect
Chilled Water: 7.0oC
Cooling Water: 30.0oC
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 15
Research Needs
• Advanced cycles
• Advanced fluids
• Heat and mass transfer in absorption/desorption
• System simulation
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 16
ABSIM Modular Simulation Tool for Absorption and
other Thermal Systems
• User-oriented, modular and flexible
• Evaluate different cycle configurations and
working fluids
• Evaluate system performance in off-design
conditions
• Perform preliminary design optimization
• Check control strategies
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 17
ABSIM - Program Structure
S OLVER 1. Condition set of equations 2. App ly constraints 3. Solve system of equations
MAIN PRO GRAM 1. Interp ret inp ut 2. Form variable vector 3. Link units and form equations martix 4. Normalize 5. Activate solver
UNIT SUBRO UTINES 1. Absorber 2. Desorber 3. Heat exchr 4. Condenser 5. Evap orator 6. Valve 7. Mixer 8. Splitter 9. Rectifier 10. Analyzer 11. Compressor 12. Pump
PRO PERTY DATABAS E
OUTPUT
USER INPUT
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 18
Alternative Approach to A/C
• Roles of Air conditioning: Reduce temperature and humidity
• Hybrid operation possible; independent control of temperature and humidity
• Latent load conventionally treated by cooling process air below its dew point
• Desiccant dehumidification performed at ambient temperature; can be powered by low grade solar or waste heat
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 19
Desiccant System Principle
Air Desiccant
QH
QL
Two types of Desiccants
• Adsorbent
• Absorbent
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 20
Liquid Desiccant vs. Absorption
Air LiCl-H2O
QH
LiBr-H2O
QH
Evap
Cond
QL QL
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 21
Cooling by controlled drying and
wetting
Dehumidifier
1
Controlled
wetting
Ambient Temp
3 2
4
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 22
Comfort
Zone
Cooling by controlled drying
and wetting
50%
70%
Saturation
100%
KgDryAir
OKgHW 2
)(0 CT
4
2
3
Desiccant
Dehumidifica
tion
Ambient HX
Wetting
1
6
5 Indirect Contact
Cooling
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 23
20-kW Solar Liquid Desiccant System at
Technion, Haifa, Israel
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 24
Control Unit - View of Computer Screen
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 25
Solar Collector Field
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 26
Liquid Desiccant System
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 27
Experimental Results – Supply air Humidity
4
5
6
7
8
9
10
11
12
10 11 12 13 14 15 16 17 18 19
Win(gr/kg)
Wo
ut-
AB
S(g
r/kg
)
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Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 29
Additional Reading
Solar Cooling, Dehumidification and Air Conditioning Technion – Israel Institute of Technology 30
Policy issues:
The Samuel Neaman Institute:
www.neaman.org.il
ac-www.ises.org.il/solarPopular article in Hebrew:
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The End
Thank You for Your Attention!
