The document discusses the implementation of CO2 transcritical systems in warm climates, particularly in southern Europe, emphasizing the efficiency of modulating ejectors. It highlights the benefits of advanced system controls and the adaptability of the technology for various cooling capacities and formats. The findings suggest significant energy savings and improved energy efficiency for food retail applications in warmer regions.

1. 1
Hall 7A
NürnbergMesse, Arbeitstitel, Datum
Chillventa Specialist Forums 2018
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2. Cristian Corato
10/2018
EmJ to boost the CO2 compressor pack
efficiency in warm climate

3. Europe background
CO2 is the mainstream technology in
Europe for food retail application
The CO2 equator is still visible,
considering the number of installations
Installing transcritical CO2 systems in
southern Europe is today feasible
Ejector technology is one of the best
options for warm climates
Source: SheccoBase
Total CO2 Stores
14000+
Southern Europe
500 (3,6%)

4. Top perfomances comes from system control stability
• Wide modulation range to always
fit the cooling capacity
• Maximum energy efficiency at
part load
• Stepper electronic expansion valves
• Continuous and precise control of
evaporator feeding
• Equi-percentual profile for perfect
control in part load operation
Opening %
Cooling
capacity
CAREL ExV
• Continuous modulation to match the
different rack requirements
• No need of high pressure valve to
modulate high pressure flow
• Maximum energy efficiency in ejector
mode
CAREL DNA: Continuous Modulation
DC technology EEV EMJ

5. Emj: Modulating Ejector
Full RANGE of MODULATING EJECTORS
• from 20 to 135 kW and up to 3 EmJ in parallel
to match different compressor rack capacities, even for
small formats
• Compact Design
• Vapour ejectors design for full mass flow
• Continuous stepper modulation to match the
different rack requirements
• Easy adaptation to all working condition and part loads
• Precise high pressure control: no compromise on
HPV function
• Simplified rack design to reduce capital investement
• Full advanced control system (rack, cabinets,
monitoring) for whole system optimization
20 kW
135 kW

6. System configuration and operating modes
Standard mode (winter)
Standard CO2 transcritical system
Parallel Comp. mode
Parallel compressor activation
Ejector mode (summer)
Ejector activation

7. • Standard booster system
• Ejector suction port is closed
• Ejector controls high pressure like a standard
modulating HPV
• Parallel compressor is not active
Standard mode (winter) – low external T
MT evap P = 26 bar
SH in cabinets = 5-10K
Rec P =
35-40
bar
Suct P =
26 bar
WINTER
mode
Ejector HP control
3Way-valve
(Vcs)
EmJ Suction
port (Vej)
CLOSED
Parallel Comp NOT ACTIVE
Flash Valve ACTIVE
Vcs
Vej

8. • Parallel compressor is active
• Flash valve is closed
• 3-way valve connects comp suction and evap outlet
• Ejector suction port is closed
• Ejector controls high pressure like a standard modulating HPV
Parallel Comp. mode
MT evap P = 26 bar
SH in cabinets = 5-10K
Rec P
= 35-40
bar
Suct P =
26 bar
WINTER
mode
MID SEASON
mode
Ejector HP control HP control
3Way-valve
(Vcs)
EmJ Suction
port (Vej)
CLOSED CLOSED
Parallel Comp NOT ACTIVE ACTIVE
Flash Valve ACTIVE NOT ACTIVE
Vcs
Vej

9. Ejector mode (Summer) – High external T
MT evap P = 28-30 bar
SH in cabinets = 3K
Rec P
= 33-38
bar
• 3-way valve connects comp suction and liquid receiver
• Ejector suction port is open
• Ejector controls high pressure modulating its opening
• Ejector provides a pressure lift from evaporator pressure to receiver
P
• All compressor work in «parallel» conditions: i.e. 33-38 bar suction P
• SH can be reduced: semiflooded Evap
Suct P =
33-38 bar
WINTER
mode
MID SEASON
mode
SUMMER
mode
Ejector HP control HP control Optimized
HP control
3Way-valve
(Vcs)
EmJ Suction
port (Vej)
CLOSED CLOSED OPEN
Parallel Comp NOT ACTIVE ACTIVE ALL
Compressors
Flash Valve ACTIVE NOT ACTIVE NOT ACTIVE
Vcs
Vej

10. Emj advanced system control
ETHTCPIP
• Fast synchronization between rack and
cabinets thanks to ethernet connectivity
• Safety and optimization is always at top
level
Rack
• Reduced number of compressors required
thanks to interchangeability of medium
temp and parallel compressors
• No need of liquid receiver
• All compressors running as parallel
compressors in summer mode
Case
• Semiflooded operation, SH=2-3K
• Stable regulation
Ethernet
switch
ETH TCPIP ETH TCPIP

11. Results from a real store
System Characteristics
Location: Spain
Cooling Capacity: 130kW MT, 40kW LT
Booster system
4 MT compressors (1° with INV) +
1 Eco Compressor
3 LT compressors (1° with INV)
3 Ejectors
44 Medium Temp cabinets
15 Medium Temp cold rooms
12 Low Temp cabinets
2 Low Temp cold rooms

12. Analysis: Data acquisition
Data Acquisition
 Sampling every 10 minutes
 6 month data (May to
October)
Compressor rack
 Temperature probes
 Pressure probes
 Compressors activation
 Ejectors opening
 Operating modes
Cabinets
 Temperature probes
 Pressure probes
Energy Meters
 General
 MT line
 LT line Supervisory system
 Alarm management
 Plant optimization
 Data logging

13. Analysis: Annual energy savings
0%
20%
40%
60%
80%
100%
0
100
200
300
400
500
600
-2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42
Ejectoractivation[%]
hours
External temperature [°C]
Temperature distribution example
EJ
Std
Activation Ejector
In hours at low temp,
Standard mode will
be active
In hours at high
temp, Ejector mode
will be active
Each column represents the
number of hours per year at
a certain temperature.

14. Results: Annual energy savings expectations
Annual average Temperature [°C]
Madrid Sevilla
Rio de
Janeiro
Sao Paulo Houston Miami Phoenix Acapulco Veracruz
14,3 18,4 24,0 19,9 20,3 24,1 23,8 27,4 25,0

15. Improvments: Annual energy savings expectations
Annual average Temperature [°C]
Madrid Sevilla
Rio de
Janeiro
Sao Paulo Houston Miami Phoenix Acapulco Veracruz
14,3 18,4 24,0 19,9 20,3 24,1 23,8 27,4 25,0
Ejector mode activation parameters
can be optimized:
• The system could work for a
longer time in EJ mode
• The transition curve could be
shifted, including more hours in
EJ mode during the year
The rack analysed worked with an
evaporation pressure setpoint in
ejector mode of 28 bar.
• It is possible to increase the
pressure setpoints to 30 bar,
with an improvement of the
energy saving

16. Conclusions
• Efficiency in warm climate is not anymore an issue thanks of modulating ejectors
• Southern Europe can profit of CO2 transcritical technology, already mature in the
northern part of the continent. Extreme saving of time and investments
• CO2 not only for big formats, Emj can offer suitable solution also for small formats.
Effective solution to improve energy efficiency.

18. 18
Hall 7A
NürnbergMesse, Arbeitstitel, Datum
Chillventa Specialist Forums 2018
Chillventa Fachforen 2018