This document discusses modulating ejectors for CO2 refrigeration systems in the United States. It notes that installations of CO2 systems have increased significantly in recent years due to improved efficiency and retailers entering the US market. Modulating ejectors allow CO2 systems to operate efficiently in various climate conditions by matching cooling capacity to demand. Test results from European stores indicate modulating ejectors can reduce energy consumption by 6-19% compared to standard CO2 systems. The document concludes that modulating ejector technology makes CO2 a viable solution for both large and small refrigeration applications in warm climates like the US.

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Modulating Ejectors
next steps for CO2 transcritical systems in the USA
Brandon Marshall
June 13th 2018

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CO2 US background
The number of installation in the US has
increased by 458% from 2015 to date
(2015-52 to 2017- 290)
Factors driving growth:
• Availability of efficient systems
• Several European retailers are
entering the USA
• ROI is being proven with the use of
modern technologies
210+
CANADA
340+
UNITED STATES
Source: sheccoBase

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Top perfomance comes from system control and 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
• Equal percentage profile for
perfect control in part load
operation
Opening %
Cooling
capacity
CAREL ExV
• Continuous modulation to match the
different rack requirements
• No need for high pressure valve to
modulate high pressure flow
• Maximum energy efficiency in ejector
mode
CO2 Continuous Modulation
DC technology EEV EMJ

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EmJ : Modulating Ejectors
Full RANGE of MODULATING EJECTORS
• Vapor ejectors are designed for full mass flow
• Continuous stepper modulation
• Easy adaptation to all working conditions and part loads
• High Pressure Valve & Modulating Ejectors in one
• Available in different sizes to match different compressor rack capacities,
even for small formats
• Simplified rack design to reduce capital investment
• Full advanced control system (rack, cabinets, monitoring) for whole system
optimization
From 20kW to 135kW

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System configuration
Winter mode
Standard CO2 transcritical system
Mid-Season mode
Parallel compressor activation
Summer mode
Ejector activation

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System control
Rack
• Ejectors working as high pressure valve in winter and mid-
season mode
• Reduced number of compressors required thanks to
interchangeability of medium temp and parallel compressors
• No need for a liquid receiver
• All compressors running as parallel compressors in summer
mode
Case
• Semi flooded operation, SH=2K
• Synchronization with rack working mode thanks to Ethernet
connectivity

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From real stores to model calculation
From real stores/labs running in Europe
1 year of data was acquired to create a
mathematical model for validation
Mode distribution
Power cons vs T
Energy saving vs T
Power abs model
Example
Spain: 130kW MT, 40kW LT
3 ejectors installed

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EmJ activation
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
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
BL
Activation Ejector

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NAM expectations
0
50
100
150
200
250
300
350
400
450
Madrid Sevilla Rio de
Janeiro
Sao Paulo Houston Miami Phoenix Acapulco Veracruz
MWh
Annual power consumption
Ejector Standard
6%
9%
15%
8% 12%
16% 14%
19%
16%

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Lab testing: 2018
Field installation planned for 2019

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Conclusions
• Efficient CO2 systems in warm climates are now viable thanks to modulating ejector
technology.
• The US market can benefit from the development and tests done in Europe. This equates to
a significant reduction in time and investment to test and implement the technology.
• «Americanization» is a key factor to global adoption of new technologies from other
continents.
• Modulating Ejector technology allows CO2 to be a viable solution for large and small format
applications by reducing system complexity and improving the energy benefits.

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