This document discusses an integrated CO2 system for refrigeration, air conditioning, and heat recovery installed in a supermarket in southern Germany. It includes: 1. Medium and low temperature compressors, a parallel compressor, heat exchangers, and valves to control the transcritical and flash gas processes. 2. The system is controlled as a single unit to reduce installation costs and space needs while improving efficiency through more precise control and optimization of refrigeration, air conditioning, and heat recovery loads. 3. Data is collected in real-time to calculate COP and divide total energy consumption between the different applications to evaluate system performance under varying operating conditions.

1. Integrated CO2 systems for
warm climates
Diego Malimpensa

2. Field experience
2 - MT : 60 kW
1 - LT : 8 kW
1 - Par : 12 m3/h
1 - H/R : 75 kW
1 - AC : 30 kW
Integrated compressor rack for medium-sized supermarket in southern Germany
Refrigeration, air conditioning & heat recovery loads

3. Field experience
1. MT Compressors
2. LT Compressor
3
2
4 5
7
8
3. Parallel Compressor
4. Heat recovery heat ex.
5. Gas Cooler & “false load”
7. Air conditioning heat ex.
8. Oil return
6
6
6. Transcritical & flash gas valves
1

4. Integration
Complete control of the entire unit on one
single device
• Lower installation costs/ space
• Increased usability (one point of access)
• Faster commissioning
• Improved efficiency

5. How to divide total energy consumption between REF – AC – HR?
Compressor power consumption [kW]
• PMT : Medium temperature compressors
• PLT : Low temperature compressors
• PPC : Parallel compressors
• PGC : Gas cooler
Integration
Heat transfer
• QAC : Air conditioning heat
• QHR : Heat recovery heat
One unit providing REF+AC+HR

6. PHR
PAC
PREF
PGCPPCPLTPMT
QAC
Rack Controller
QHR
How to divide total energy consumption between REF – AC – HR?
Site status reading: main variables, energy consumption, heat transfer
Real time COP calculation, division of power consumption
Integration

7. Integration
Temperatures
Pressures
Comps data
Entalpies
Qualities
COPHR
COPAC
COPREF
PHR PAC
PREF
Air conditioning mode
Heat Reclaim mode
Higher gas cooler pressure
Higher quality of vapour
𝐶𝑂𝑃 𝐻𝑅 𝑂𝑁
𝐶𝑂𝑃 𝐻𝑅 𝑂𝐹𝐹 [𝑇]
=
𝑃 𝐻𝑅 𝑂𝑁
𝑃 𝐻𝑅 𝑂𝐹𝐹
Higher quality of vapour
Mass refrigerant flow 𝑚 𝐴𝐶

8. PARALLEL COMPRESSOR
Receiver pressure control
Activated with sufficient flash gas
Flash gas valve synchronisation
Higher efficiency
• High gas cooler pressure
• AC load
• Heat recovery
Higher efficiency at higher outside temperature
RPRV
HPV
Warm Climates

9. 00
10
20
30
40
50
60
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
PowerConsumption[kW]
Outside temperature [°C]
Power consumption vs Temperature
Booster with Flash Valve Booster with Parallel compressor
Parallel compressor
enabled to run only when
outside temperature higher
than 15°C
Warm Climates
-15%

10. 0
20
40
60
80
100
120
140
160
180
200
Munich [8°C] Venice [13°C] Palermo [18°C]
PowerConnsumption[kW]
Energy consumption comparison
Booster with Flash Valve Booster with Parallel Comp
-4%
-10%
Warm Climates
-7%

11. 0
20
40
60
80
100
120
140
160
180
200
Munich [8°C] Venice [13°C] Palermo [18°C]
PowerConnsumption[kW]
Energy consumption comparison
Booster with Flash Valve Cascade R134a/CO2 Booster with Parallel Comp
Warm Climates
-10%
-6%
≈

12. Warm Climates
italian transcritical CO2 systems (Carel 2013)
lab testing
real spmkt