Institute of Air-handling and Refrigeration (ILK Dresden)
Development of a small capacity
directly air-cooled water/LiBr absorption chiller
Chinese Solar Cooling Conference, Shanghai, 27.3.2015
ILK Dresden – R&D company
Founded in 1964
Re-established as independent
research institute in 1991
Employees: 145
Academics: 72 %
mean age: ~44
Laboratory area: ~3000 m²
Test rigs: ~56
Phys. / Chem. Laboratories: 25
2 27.03.2015 Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik
Background and goal of the development
Problems in solar thermal cooling systems with small scale chillers
Complexity of the system
Interface problems because of different crafts (might be) involved
Possibly high error rate during installation
Auxiliary energy demand of the system
Limited applicability of evaporative systems but high re-cooling
sensibility of the cycle
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 3 27.03.2015
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 4
Challenges
Avoiding of an intermediate circuit:
- to minimize the auxiliary energy demand (as re-cooling circuit pump
usually consumes much electricity)
- for a better approach of external and internal temperatures since
temperature lift and driving temperature are limited
Air-cooled absorber needed
Water as refrigerant -> big free section needed
Air as heat transfer media -> big free section needed
?
27.03.2015
Distribution of the auxiliary energy demand
of a small scale water cooled absorption chiller
Nominal cooling capacity: 19,4 kW
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 5
35 %
22 % 25 %
27.03.2015
Auxiliary energy demand of the system
Auxiliary energy demand of the system with constant
speed pumps/fans as a function the cooling capacity
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 6 27.03.2015
Distribution of auxiliary energy demand
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 7 27.03.2015
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 8
Examples of air-cooled absorption chillers
H2O/LiBr, rotating HX,
intermediate circuit
NH3/H2O -> high working pressure!
Gas driven -> high driving temperature
Source Helioplus
Source: Rotartica
27.03.2015
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 9
Examples of air-cooled absorption chillers
H2O/LiBr, gas driven, intermediate
circuit
Q0=23 kW; zetta=1,1, Pel=1,8kW
(COPel=12,7)
27.03.2015
Source: Broad
Source: Broad
Balancing Single Lift vs. Double Dift
chilled water out: 13 °C
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 10 27.03.2015
60
65
70
75
80
85
90
95
100
105
110
115
120
125
130
20 25 30 35 40 45 50
tL,e [°C]
t HW
,e [
°C]
0,1
0,15
0,2
0,25
0,3
0,35
0,4
0,45
0,5
0,55
0,6
0,65
0,7
0,75
0,8
zre
al [-
]
durchgezogen - Double Lift / gestrichelt - Single LiftSolid lines – single effect/double lift; dashed lines – single-effect/single lift
Aimed specifications for the development
Condenser and Absorber directly air-cooled
Outdoor installation, frost save
Auxiliary energy consumption at nominal conditions < 60 Wel/kW0 („EER“ > 16)
Single effect / single lift
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 11 27.03.2015
External Fluid Nominal Condition Operating Range
Chilled water temperature
(water w. 20 % Glycol) 18 °C / 13 °C (in/out) 6 °C … 20 °C (out)
Heating water temperature
(water w. 20 % Glycol) 95 °C / 87 °C (in/out) 75 °C … 105 °C (in)
Ambient air (for re-
cooling) 32 °C / 42 °C (in/out) 10 °C … 32°C (in)
Cooling capacity 8 kW
Test of components within functional model
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 12 27.03.2015
Improved functional model
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First lab results
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 14 27.03.2015
0,55
0,60
0,65
0,70
0,75
0,80
6
7
8
9
10
11
12
9 10 11 12 13 14 15 16 17
EER
th[-
]
coo
ling
po
wer
[kW
]
chilled water outlet temperature [°C]
cooling power and EERth
95 | var | var
95 | 25 | var95 | 30 | var95 | 35 | vardesign point (95 | 32 | 13)EER_th 95 | 25 | varEER_th 95 | 30 | varEER_th 95 | 35 | var
25
30
35
35
30
35
0,55
0,60
0,65
0,70
0,75
0,80
6
7
8
9
10
11
12
9 10 11 12 13 14 15 16 17
EER
th[-
]
coo
ling
po
wer
[kW
]
chilled water outlet temperature [°C]
cooling power and EERth
95 | var | var
95 | 25 | var95 | 30 | var95 | 35 | vardesign point (95 | 32 | 13)EER_th 95 | 25 | varEER_th 95 | 30 | varEER_th 95 | 35 | var
0,55
0,60
0,65
0,70
0,75
0,80
6
7
8
9
10
11
12
9 10 11 12 13 14 15 16 17
EER
th[-
]
coo
ling
po
wer
[kW
]
chilled water outlet temperature [°C]
cooling power and EERth
95 | var | var
95 | 25 | var95 | 30 | var95 | 35 | vardesign point (95 | 32 | 13)EER_th 95 | 25 | varEER_th 95 | 30 | varEER_th 95 | 35 | var
Restrictions of lab measurements
Limited space and height in lab
No free outflow of absorption chiller outlet air
-> increased air-side counter pressure
-> higher fan speed for same air flow rate needed
-> increased power consumption of fan
=> no meaningful results regarding EERel
Difficulty to maintain even temperature
distribution
27.03.2015 Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 15
Conclusion and Outlook
Thermal design point reached
No useful results regarding electrical efficiency yet
Field test planned in summer 2015
Results expected regarding
Electrical efficiency
Operational experience
Outdoor installation
Directly air-cooled absorption chiller - Chinese Solar Cooling Conference 2015 - M. Safarik 16 27.03.2015
Vacuum ice slurry technology for high density cold
storage, e.g. in PV driven cooling systems
High energy density (93 kWh/m³)
Higher efficiency than conventional ice bank
storage through high evaporation temperature
No glycol circuit needed
Ice slurry is pumpable
Capacity range: 50 … 500 kW
Matching solar radiation and cooling demand
Efficient cooling, cold storage or heating using vacuum ice slurry 17
ILK Dresden Department of Applied Energy Engineering
Bertolt-Brecht-Allee 20; 01309 Dresden; Germany
Dr.-Ing. Mathias Safarik
Tel.: +49 351 4081-700
E-Mail: [email protected]
Thanks for your attention!
Questions?
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