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NATIONAL RESEARCH COUNCIL OF ITALY
Institute for Advanced Energy Technologies “Nicola Giordano”
Thermally driven adsorption heat pumps: recent
advancements and future technical challenges
Giovanni Restuccia
Problématiques Scientifiques et Technologiques
dans les Procédés Frigorifiques et Thermiques à Sorption
Paris 7/2/2014
SUMMARY
Basics
Current market Situation
R&D priorities
Novel Adsorbent Materials
Adsorbent coatings
Adsorption machine components
Machine optimization and control
Recent advancement at CNR-ITAE
SUMMARY
Basics
Current market Situation
R&D priorities
Novel Adsorbent Materials
Adsorbent coatings
Adsorption machine components
Machine optimization and control
Recent advancement at CNR-ITAE
Thermally Driven ADsorption Machines
OPERATING PRINCIPLE
Condenser
Condenser
Bed
1
Bed
2
Bed
1
Bed
2
Evaporator
Evaporator
Condenser
Condenser
Bed
1
Bed
2
Bed
1
Bed
2
Evaporator
Evaporator
Thermally Driven ADsorption Machines
PERFOMANCE AND DRAWBACKS
Less studied and developed
than liquid sorption
Not a mature technology
Few products on the market
Can be efficiently driven by a heat source at a
temperature as low as 60- 80 °C
Environmental friendly refrigerants (water)
Silent operation
APPLICATIONS
CHP units, process heat
Solar collectors
District heating
Automotive waste heat
HEAT SOURCES FOR ADSORPTION CHILLERS
o (Low-grade) waste heat recovery
o Tri-generation
o Air conditioning in vehicles or boats
o Solar cooling
SUMMARY
Basics
Current market Situation
R&D priorities
Novel Adsorbent Materials
Adsorbent coatings
Adsorption machine components
Machine optimization and control
Recent advancement at CNR-ITAE
Brief history of adsorption chiller development
2000 – today
reliable products developed
(better heat transfer quality, materials,
controls)
1990 – 2000
No commercial products strong enough
to survive, apart the Mycom silica gel
/water chiller
1980 – 1990
Early studies and prototypes
Meunier, Guilleminot, Pons et al. in Paris (AC/Meth, Zeolite/H2O)
Tchernev in USA (zeolite/water)
Shelton in USA (AC/Ammonia)
Spinner in Perpignan (hygroscopic salts)
Cacciola and Restuccia in Italy (zeolite/water)
Groll in Germany (metal hydrides)
Alefeld in Germany (zeolite/water)
Current market situation
SMALL SIZE UNITS
SWAC-10
chiller
water-fired
silica
gel/water
10 kW
China
Current market situation
SMALL SIZE UNITS
AQSOA
chiller
water-fired
zeolite/water
10 kW
Japan
Current market situation
HIGH-CAPACITY CHILLERS
AdRef-Noa
chiller
water-fired
zeolite/water
105kW - 430kW
Japan
Ad3
chiller
water-fired
silica gel/water
35 to 600 kW
USA
Current market situation
COMPARISON
The current market for solid sorption
heat pumps is very small, due to:
• High capital costs
• Still too big and too heavy to compete
with conventional systems
• Lower thermal efficiency and power
density than liquid sorption systems
Advanced prototypes realized at:
Warwick University (UK)
ECN (NL)
SJTU (Ch)
CNR ITAE (IT)
Adsorption chillers/heat pumps development
MAIN ACTORS INVOLVED
ASIA
SUMMARY
Basics
Current market Situation
R&D priorities
Novel Adsorbent Materials
Adsorbent coatings
Adsorption machine components
Machine optimization and control
Recent advancement at CNR-ITAE
Future challenges
Today a limited number of materials
is used!
Materials
New or modified adsorbents
needed
Stability over several thousand
cycles
Compact, lightweight, high
surface area HEXs and
adsorbent reactors
Compact and low cost
evaporator and condenser
Components
for
adsorption
machines
Coated adsorbent reactors
Machine
optimization
control &
integration
Advanced control strategies
Compact and modular system
designs
SUMMARY
Basics
Current market Situation
R&D priorities
Novel Adsorbent Materials
Adsorbent coatings
Adsorption machine components
Machine optimization and control
Recent advancement at CNR-ITAE
Development of advanced adsorbent materials
The adsorbent material is a key-element of an adsorption machine
Initially, adsoption heat transformers were
realized using not optimized adsorbents
(Zeolite 4A, X, silica gel)
New generation of adsorption machines requires novel
adsorbent materials with optimal adsorption properties
Tdes
∆W = ∆W
Tads
“New” adsorbent materials
Composite
Adsorbents
«salt in matrix»
(Selective
Water
Sorbents)
Modified
Zeolites
(dealuminated
zeolites,
MeAPO)
Metallic
Organic
Frameworks
(MOFs) (Major
trend)
The solution
must be
stable and
cheap.
Classical zeolites (4A, 13X, DDZ 70 UOP)
Aluminophosphates (SAPO34, AQSOA
FAMZ02 from MITSUBISHI Plastics)
Microporous silica gel (e.g. Fuji Davison
type RD)
Porous Carbons (ammonia and alchools
adsorbate)
SWS-Selective Water Sorbents
INITIAL STATE
porous host
matrix
impregnated
anhydrous salt
solid crystalline
hydrates
Q
<salt>
+ H2O
sorption
Q
<salt> ∙ n
<sorbate>
+ H2O
sorption
- H2O
desorption
+ H2O
sorption
n
<sorbate>
FINAL STATE
solid crystalline
hydrates
salt aqueous
solution
<sorbate> = water, methanol, ethanol, ammonia
Ca(NO3)2 + 2 H2O = Ca(NO3)2∙2H2O
BaBr2 + 8 NH3 = BaBr2∙8NH3
LiCl + 3 CH3OH = LiCl∙3CH3OH
LiBr + 3 C2H5OH = LiBr∙3C2H5OH
SWS-Selective Water Sorbents
SORPTION CHARACTERISTICS
MOF-Metall Organic Frameworks
MOF-Metall Organic Frameworks
Commercially available MOFs: (BASF - Basolite®)
Oxygen
Carbon
Hydrogen
Copper
Basolite C300 (HKUST-1) structure
Basolite® C300 (HKUST-1): Copper-based
MOF, trimesate trianions as linkers. It is also
known as Cu(BTC).
Basolite® F300: Iron-based MOF, trimesate
trianions as linkers.
Particle size
distribution
15.96 μm
Particle size
distribution
~ 20 μm
Surface area
BET surf. area 15002100 m2/g
Surface area
BET surf. area 13001600 m2/g
Bulk density
0.35 g/cm3
Bulk density
0.35 g/cm3
Cost
~ 95 €/(10 g)
Cost
~ 85 €/(10 g)
MOF-Metall Organic Frameworks
STABILITY ISSUE
30
27.5
Water Uptake [wt.%]
25
∆W = - 6 wt %
22.5
BASOLITE C-300: Water adsorption capacity
reduction after 5 ad/desorption steps!
20
17.5
15
12.5
10
7.5
5
2.5
0
20
30
40
50
60
70
80
90
100
110
120
130
140
150
Temperature [ C]
Ba solite C-300 Ba sf 9.9 mbar Ads. 1
Basolite C-300 Basf 9.9 mba r Ads. 2
Ba solite C-300 Ba sf 10.1 mba r Ads. 4
Basolite C-300 Basf 10.1 mbar Ads. 5
Ba solite C-300 Ba sf 10 mbar Ads. 3
160
Database of Adsorbent Materials
A DATABASE of adsorbent materials was created within the IEA - Annex 34
“Thermally Driven Heat Pumps for Heating and Cooling”
Databasing of adsorbents is continuing within the new
Annex 43 “fuel driven sorption heat pumps”.
30
27.5
25
Water Uptake [wt.%]
22.5
20
17.5
15
12.5
10
7.5
5
2.5
0
20
40
60
80
100
120
140
160
180
Temperature [°C]
AQSOA-FAMZ02 11.8 mbar
UOP DDZ70 10.8 mbar
Tiajin SAPO 34 11 mbar
Union Carbide Na-Y 12.2 mbar
Fuji Davidson 12 mbar
Oker Chemie Silica Gel Siogel 10 mbar
Zeolyst CBV-100 10.7 mbar
BASF Basolite C300 9.9 mbar
BASF Basolite F300 9.8 mbar
200
Overall comparison of adsorbents
Material
Ability to be
regenerated at low T
Maximum adsorption
capacity
Hydrothermal stability
AQSOA – Z02
+
+
+
NaY UnionCarbide
-
+
+
NaY CBV-100
-
+
+
DDZ70
-
+
+
Fuji Davidson
+
-
+
Basolite C300
+
+
-
SAPO 34
+
+
-
Siogel
+
-
+
Basolite F300
+
-
-
AQSOA Z02 is the best material for low T application
SUMMARY
Basics
Current market Situation
R&D priorities
Novel Adsorbent Materials
Adsorbent coatings
Adsorption machine components
Machine optimization and control
Recent advancement at CNR-ITAE
Coated adsorbers
HEAT TRANSFER CHARACTERISTICS
Intensification of the heat
transfer quality in
adsorbers is a key-factor
for development of
dynamically efficient
adsorption refrigeration
and heat pump systems
λeq= 0.09 W/m K
• WHTC= 10 W/m2 K
λeq=0.4 W/m K
• WHTC= 100-400 W/m2 K
λeq= 10 W/m K
• WHTC= 20 W/m2 K
λeq=0.6 W/m K
• WHTC= >1000 W/m2 K
Coated adsorbers
DEVELOPMENT STEPS
Grains
-
coating
-
synthesis
SUMMARY
Basics
Current market Situation
R&D priorities
Novel Adsorbent Materials
Adsorbent coatings
Adsorption machine components
Machine optimization and control
Recent advancement at CNR-ITAE
Components for Adsorption Machines
Utilization of compact, lightweight, high surface area HEXs is mandatory
for realization of dynamically efficient adsorbent beds
Optimization of the HEX • (H&M transfer properties, thermal
mass, flow field)
design
Optimal configuration
of the “adsorbent –
HEX” (AdHex) unit
Corrosion
• Optimal adsorbent mass per 1 m2
of HEX
• Optimal size of the adsorbent
Is it a real issue?
Coatings offer a barrier effect
Components for Adsorption Machines
Increased dynamic efficiency of the AdHex unit asks for
compact and efficient evaporator and condenser
The heat transfer between tube wall and refrigerant and
between tube wall and chilled water circuit have to be
increased through:
o Increasing of the specific surface area
o Improvement of the heat transfer coefficient
o Increasing the volume flow and the turbulence inside the
tube
a
a
a
SUMMARY
Basics
Current market Situation
R&D priorities
Novel Adsorbent Materials
Adsorbent coatings
Adsorption machine components
Machine optimization and control
Recent advancement at CNR-ITAE
Machine optimization
IMPROVED CYCLES
Thermal wave
Heat and/or mass recovery
Cascades cycles
Multiple beds
Today the trend is to use low regeneration T.
Most developers are using the simple cycle, especially
for low temperature applications
Machine optimization
Bed 1
MANAGEMENT STRATEGY
Isosteric
Isosteric
Desorption
Adsorption
Adsorption
Bed 2
Isosteric
Desorption
Isosteric
UP TO 30% COP INCREASING
Very short duration of
the isoteric stages
Identification of the
optimal cycle time for
a given operating
condition
Desorption rate is
faster than
adsorption, due to
higher temperature
and vapor pressure
SUMMARY
Basics
Current market Situation
R&D priorities
Novel Adsorbent Materials
Adsorbent coatings
Adsorption machine components
Machine optimization and control
Recent advancement at CNR-ITAE
ITAE’s Coating Technique
Inorganic (clay-based) binder
Organic binder
collaboration
UNIME
–
in
with
Preparation of the Coated Adsorbers
Coating technique: The original lamella HEX in aluminum was coated
by pouring a SAPO-34 zeolite – polymeric binder (5 wt.%) solution
through the lamellas …
…drying at room temperature, then heating at 120 °C in oven.
• binder thermally resistant in the T-range of application
• coating thickness can be controlled (0.1- 0.7 mm) by multi-layer deposition
The prepared adsorbers
ITAE coating performance evaluation
HEX filled
with grains
10
10
20
Coated HEX
Cycle time, min
Wall Heat Trans. Coeff., W/m2K
Specific cooling power W/kgads
5
100
300
Adsorption Chiller for Automotive Applications
Thermally OPerated Mobile Air Conditioning Systems
TORINO
Overall volume
150 L
Overall weight
59 kg
Chilling capacity
2,3 kW
Min, air temperature
9 °C
COP
0,2
Regeneration temp.
Adsorbent
80 °C
Zeolite
o SCP: up to 600 W/kg
o Very competitive weight
considering commercial
products!
o Volume density higher than
10kW/m3!
Prototype
57 cm
STRALIS 520
Cabin installation
Solar Cooling System for Residential Application
Technology of solar thermal collectors
Number of evacuated tubes
Total thermal collectors area [m2]
Heat storage volume [m3]
Tilt angle [°]
Gas Boiler nominal Power [kW]
AHP cooling Power [kW]
Required Cooling Load [max, kW]
Cold delivering system
Overall radiant surface [m2]
Evacuated tubes
90
9.6
0.5
20
20
8
2.43
Flat radiant panel
28
Test facility for Trigeneration Systems
•
75 kW heat source up to 99 °C
•
15 – 50 °C discharging T ability
•
2 – 20 °C Low T simulation ability
•
1500 litres High Temperature
High Temp Storage
99°C Heat Source
Storage
•
1000 litres Low Temperature
Storage
•
Variable flow hydraulic pumps
•
High accuracy sensors
•
Pressure drop measurements
•
Full automatic operation
Management/
measurements
Low Temp.
Storage
System under testing
(overnight tests!)
•
UNI-EN 12977 – III (possible tests
on storages for solar application)
Piping
Testing of chillers up to 35-40 kW cooling
Thermal energy storage test (max charging rate 75 kW – discharging 63 kW
ICE or Fuel cell Cogenerator
Conclusions
Development will be mainly technological
Better materials
Enhanced heat transfer/HEX
Optimized management strategy
Techno-economic optimization
Scientific issues
Material science (adsorbents, etc.)
From thermodynamic to adsorption dynamics
Thank you!
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