DX rear coolers using
CO2 with Heat Recovery
Principle of the solution
The Focus Cooling system is a Direct Expansion rear door cooler installed on Data Centre
server racks. In resume, the indoor unit cools the hot air from inside the rack, prior to exiting
and rejects this heat into the atmosphere externally via an outside remote condenser.
To find out how it works please watch the following video.
https://www.youtube.com/watch?v=zK2oVzrqsPU
This Indoor Unit is equipped with a coil in order to reduce the temperature of the output hot
air. Inside the coil the refrigerant turns into vapor. Due to the location of the coil, which is very
close to the heat source, the hot and cold air do not get mixed and the thermodynamic
process is very efficient. The temperature of the coil is similar to the ambient room
temperature, so the thermal load is neutralized. All this heat energy is transported through
the refrigerant pipes until the heat is expelled by an outdoor unit. In that unit vapor turns into
liquid and the refrigerant completes the cycle by going back to the indoor unit. Each Indoor
Unit adapts itself to the specific load of each given moment, thus avoiding an excess or lack
of cooling.
The heat recovery system
In the system, when the ‘refrigerant’ CO2 (R744) is used, there is the option to utilize a heat
recovery system. Instead of releasing the heat from the compressed gas to the atmosphere
via the gas cooler, Focus Cooling outdoor units give the user the option to choose heat
recovery. The recovered heat can be used for water or heating of air, or both if so desired.
Due to the high temperature of compressed gas, it is possible to achieve water temperatures
in the 70-80°C range.
The control of the heat recovery consists of four steps, depending on the heat requirement.
Step 1: The 3-way valve (By pass heat recovery exchanger) is set so the discharge gas flows
through the heat exchanger, and the water pump is started. The heat recovery has started
Step 2: By gradually increasing the gas cooler pressure, the temperature of the discharge
gas is increased. This is useful if a higher temperature and capacity on the water side is
required.
Step 3: The gas cooler fans are stopped. A minimal amount of heat is lost to the
environment.
Focus Cooling
C/ Johannes Kepler 17
50015 Zaragoza
Tel + 34 876 600 014
www.focuscooling.es
2
Step 4: The 3-way valve (By pass heat condenser) is set so the gas cooler is bypassed. The
heat recovery reaches 100%.
Benefits of the Heat Recovery
For example, in a 10 rear rack cooler system of a total cooling capacity of 200kW, the supply
of hot water can be up 240 kW (200kW of the IT energy plus 40 kW of the compressors
energy consumption). When the hot water requirement is greater than the heat supplied by
the compressed gas the fans of the condenser/ gas cooler are stopped so decreasing the
consumption of the cooling system.
It is remarkable, that with this system the water temperature supply can achieve a very
directly useable 70 to 80 ºC temperature range without supplementary heat input sources.
Focus Cooling
C/ Johannes Kepler 17
50015 Zaragoza
Tel + 34 876 600 014
www.focuscooling.es
3
Mechanical Data Outdoor Unit FC-UE
Unit
FC-UE 75 kW CO2
Capacity
Nominal Cooling (Gross) (1) kW
Nominal Power Input (1) kW
Nominal COP (1)
Capacity Modulation %
Dimensions W x D x H in mm
Construction
Fan Motor
80.08
27
3.78
26 to 100%
3240 x 2200 x 2550
Panels: Galvanised Sheet Steel; Epoxy Baked
Powder Coated
Axial fans with high efficiency aerodynamic blades
and electric motors
EC
Motor Type
2 x 800 mm
Quantity x Fan ø in mm
48 dB(A) @ 10m in free field
Noise Level of Unit
Compressor
Quantity
Refrigerant Type
Refrigerant Reservoir Charge (l)
Safety
Reciprocating with Frequency Converter
2
R744 (CO2)
150
Emergency condensing unit (UPS system is not
supplied)
Connections
Discharge Line
Design pressure 120 bar
Suction Line
Design pressure 60 bar
(1) At 32ºC Outdoor Temperature
Focus Cooling
C/ Johannes Kepler 17
50015 Zaragoza
Tel + 34 876 600 014
www.focuscooling.es
4
Unit
FC-UE 150 kW CO2
Capacity
Nominal Cooling (Gross) (1) kW
Nominal Power Input (1) kW
Nominal COP (1)
Capacity Modulation %
Dimensions W x D x H in mm
Construction
Fan Motor
156.50
52
3.62
26 to 100%
3240 x 2200 x 2550
Panels: Galvanised Sheet Steel; Epoxy Baked
Powder Coated
Axial fans with high efficiency aerodynamic blades
and electric motors
EC
Motor Type
3 x 800 mm
Quantity x Fan ø in mm
50 dB(A) @ 10m in free field
Noise Level of Unit
Compressor
Quantity
Refrigerant Type
Refrigerant Reservoir Charge (l)
Safety
Reciprocating with Frequency Converter
2
R744 (CO2)
150
Emergency condensing unit (UPS system is not
supplied)
Connections
Discharge Line
Design pressure 120 bar
Suction Line
Design pressure 60 bar
(1) At 32ºC Outdoor Temperature
Focus Cooling
C/ Johannes Kepler 17
50015 Zaragoza
Tel + 34 876 600 014
www.focuscooling.es
5
Unit
FC-UE 200 kW CO2
Capacity
Nominal Cooling (Gross) (1) kW
Nominal Power Input (1) kW
Nominal COP (1)
Capacity Modulation %
Dimensions W x D x H in mm
Construction
Fan Motor
203.37
64
3.83
15 to 100%
4280 x 2200 x 2550
Panels: Galvanised Sheet Steel; Epoxy Baked
Powder Coated
Axial fans with high efficiency aerodynamic blades
and electric motors
EC
Motor Type
4 x 800 mm
Quantity x Fan ø in mm
50 dB(A) @ 10m in free field
Noise Level of Unit
Compressor
Quantity
Refrigerant Type
Refrigerant Reservoir Charge (l)
Safety
Reciprocating with Frequency Converter
3
R744 (CO2)
300
Emergency condensing unit (UPS system is not
supplied)
Connections
Discharge Line
Design pressure 120 bar
Suction Line
Design pressure 60 bar
(1) At 32ºC Outdoor Temperature
Focus Cooling
C/ Johannes Kepler 17
50015 Zaragoza
Tel + 34 876 600 014
www.focuscooling.es
6
Unit
FC-UE 300 kW CO2
Capacity
Nominal Cooling (Gross) (1) kW
Nominal Power Input (1) kW
Nominal COP (1)
Capacity Modulation %
Dimensions W x D x H in mm
Construction
Fan Motor
305.80
93
3.84
15 to 100%
5320 x 2200 x 2550
Panels: Galvanised Sheet Steel; Epoxy Baked
Powder Coated
Axial fans with high efficiency aerodynamic blades
and electric motors
EC
Motor Type
5 x 800 mm
Quantity x Fan ø in mm
60 dB(A) @ 10m in free field
Noise Level of Unit
Compressor
Quantity
Refrigerant Type
Refrigerant Reservoir Charge (l)
Safety
Reciprocating with Frequency Converter
3
R744 (CO2)
300
Emergency condensing unit (UPS system is not
supplied)
Connections
Discharge Line
Design pressure 120 bar
Suction Line
Design pressure 60 bar
(1) At 32ºC Outdoor Temperature
Focus Cooling
C/ Johannes Kepler 17
50015 Zaragoza
Tel + 34 876 600 014
www.focuscooling.es
7
Mechanical Data Indoor Unit FC-D
FC-D/15kW
CO2/42U/600mm
FC-D/30kW
CO2/42U/600mm
Nominal Cool. Cap (1) kW
17.3
37.4
Sensible Capacity (1) kW
17.3
37.4
25 to 100%
25 to 100%
Unit
Capacity
Capacity Modulation %
Dimension H x W x D
(mm)
2400 x 600 x 330
Weight- Machine
60
80
Inner Volume (l)
2.74
6.91
Construction
Panels: Galvanised Sheet Steel; Epoxy Baked Powder Coated
Colour
RAL 7016 (Grey)
Fan
Redundancy
Configuration
N+1
N+1
Fan Motor
Axial fans with high efficiency aerodynamic blades
Motor Type
AC
Quantity x Motor Size (kW)
Maximum
Air
3
Flow (m /h)
4 x 0.10 (Total 0.4)
Volume
6600
Refrigerant Type
R744
Power Supply
230 V/ 50-60 Hz
Consumption
500W
Connections
Liquid mm
Ø 12 mm
Ø 22 mm
Suction mm
Ø 16 mm
Ø 22 mm
Focus Cooling
C/ Johannes Kepler 17
50015 Zaragoza
Tel + 34 876 600 014
www.focuscooling.es
8
Sound Data Indoor Unit FC-D
Sound Data
Overall
Frequency (Hz) dB
dB(A)
Overall Lw
63
125
250
500
1000
2000
4000
8000
80
66
68
74
75
73
74
74
69
72
58
60
56
57
55
56
56
61
74
60
62
69
69
67
68
68
63
66
52
54
61
61
59
60
60
55
3
100% (6600 m /h)
Sound Pressure @
1m
3
100% (6600 m /h)
Overall Lw
3
75% (4800 m /h)
Sound Pressure @
1m
3
75% (4800 m /h)
Outdoor Unit FC-UE CO2 series
Focus Cooling
C/ Johannes Kepler 17
50015 Zaragoza
Tel + 34 876 600 014
www.focuscooling.es
9