Development of a small capacity directly air-cooled water/libr absorption chiller

Size: px
Start display at page:

Download "Development of a small capacity directly air-cooled water/libr absorption chiller"

Transcription

1 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,

2 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 Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 2

3 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 M. Safarik 3

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 Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 4

5 Distribution of the auxiliary energy demand of a small scale water cooled absorption chiller 35 % 22 % 25 % Nominal cooling capacity: 19,4 kw Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 5

6 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 M. Safarik 6

7 Distribution of auxiliary energy demand Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 7

8 Examples of air-cooled absorption chillers Source Helioplus H 2 O/LiBr, rotating HX, intermediate circuit Source: Rotartica NH 3 /H 2 O -> high working pressure! Gas driven -> high driving temperature Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 8

9 Examples of air-cooled absorption chillers Source: Broad Source: Broad H 2 O/LiBr, gas driven, intermediate circuit Q 0 =23 kw; zetta=1,1, P el =1,8kW (COP el =12,7) Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 9

10 Balancing Single Lift vs. Double Dift 130 Solid lines single effect/double durchgezogen lift; dashed - Double lines Lift single-effect/single / gestrichelt - Single Lift lift 0, , , , , ,55 thw,e [ C] ,5 0,45 0,4 zreal [-] 85 0, ,3 75 0, ,2 65 0, , t L,e [ C] chilled water out: 13 C Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 10

11 Aimed specifications for the development 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) Ambient air (for recooling) Cooling capacity 95 C / 87 C (in/out) 75 C 105 C (in) 32 C / 42 C (in/out) 10 C 32 C (in) 8 kw Condenser and Absorber directly air-cooled Outdoor installation, frost save Auxiliary energy consumption at nominal conditions < 60 W el /kw 0 ( EER > 16) Single effect / single lift Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 11

12 Test of components within functional model Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 12

13 Improved functional model Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 13

14 EER th [-] EER th [-] cooling power [kw] EER th [-] First lab results 12 cooling power and EER th 95 var var 0, cooling power and EER th 95 var var 0, ,75 0,70 0,65 0, design EER_t EER_t EER_t 6 0,75 0, var var chilled water outlet temperature 0,70 [ C] var 0,75 design point ( ) var EER_th var var 0,65 EER_th var 0, var EER_th var design point ( ) EER_th var 0,60 0,65 EER_th var 0,55 Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 14

15 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 EER el Difficulty to maintain even temperature distribution Directly air-cooled absorption chiller - Chinese Solar Cooling Conference M. Safarik 15

16 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 M. Safarik 16

17 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: kw Matching solar radiation and cooling demand Efficient cooling, cold storage or heating using vacuum ice slurry 17

18 Thanks for your attention! Questions? ILK Dresden Department of Applied Energy Engineering Bertolt-Brecht-Allee 20; Dresden; Germany Dr.-Ing. Mathias Safarik Tel.: