2. History of using CO2 as refrigerant
1850 Aleksandar Twining in his British patent suggested CO2 as
refrigerant
1867 Thaddeus S.C. Lowe (adviser of Abraham Lincoln) experimented
with military balloons and designed first ice making device with CO2.
He also constructed device for transport frozen food on ships.
1920 – 1930 systems with CO2 are at their peak, mostly in marine
applications, while NH3 was mostly used on land.
By apearing of “Freon” R12 use of CO2 significantly dropped, mostly
because of drop of cooling capacity and high pressure on higher
outside temperatures.
1993 New focus on CO2 as natural refrigerant, encouraged by limitations
of CFC i HFC as well as demands to limit amount of NH3 in
installations.
2
3. History of using CO2 as refrigerant
CO2 compressor
from 1900
Peak of CO2 usage
Suggestion to use
CO2 as refrigerant
(Alexander Twining, Rediscover of CO2
British patent) cooling technology
(Gustav Lorentzen)
1850 1920 ----------1930 1960 1993
3
4. Characteristics of CO2
(Carbon dioxide / R744)
• Natural substance ( ODP = 0 ; GWP = 1 )
• Refrigerant classified as non toxic and non flammable
• Dangerous for humans if concentration exceeds 5000 ppm (0,5% v/v)
• Odourless
• Heavier than air (app 1,5 times)
• High volumetric cooling capacity
smaller dimensions of suction pipeline
smaller compression volume in compressor
• Compatible with most of materials (non corrosive)
• Less sensitive to pressure drop in pipeline
• Low critical point (31° high triple point (-56.6° C)
C),
4
5. Characteristics of CO2
(Carbon dioxide / R744)
• High volumetric cooling capacity
smaller dimensions of suction pipeline
smaller compression volume in compressor
• Low viscosity liquid and gas pipelines (small pressure drop)
• High coefficient of heat exchange during evaporation and
condensation
• Compatible with most of materials (non corrosive)
• Less sensitive to pressure drop in pipeline
• Low critical point (31° high triple point (-56. 6°
C), C)
5
6. Drivers of future refrigerants
Tradition ….
Environmental
Protection
Charges or Initial
subvention costs
Buduće
Legislations Efficiency
rješenje
“Green” Sustainable
profile development
Safety
6
7. Global warming potential GWP i
Ozone depletion potential ODP
Global Warming Potential (GWP)100a
20.000
protokol
Kyoto
4.000
R404A
2.000
Montreal
protokol
7
9. Global warming in perspective
What is the mileage you can
make with Volkswagen Golf 2.0
TDI in order to emit same amount
of CO2 equivalent to leakage of
1kg R404A.
30.000 km
Equatorial Retail store with 500 kg
load of R404A and 10%
circumference of early leakage means
the Earth 1.500.000 km**
40.070 km! * CO2 emission per km. 129 g/km
**GWP of 404a is 3983 according to IPCC AR4
(100 year radiative forcing)
10. CO2 - a natural choice for refrigeration
• No tax on refrigerant
• No charge limitation
• Cascade systems applicable in all weather conditions
• Green profile
• Less energy consumption than indirect systems
• One refrigerant ( transcritical)
• Simple system (transcritical)
CO2
11. CO2 in comparison with other refrigerants
Refrigerant R134a R404a NH3 CO2
Natural substance NO NO YES YES
Ozone Depletion Potential (ODP) * 0 0 0 0
Global Warming Potential (GWP) * 1300 3784 - 1
Critical point bar 40.7 37.3 113 73.6
°C 101.2 72 132.4 31.1
Triple point bar 0.004 0.028 0.06 5.18
°C -103 -100 -77.7 -56.6
Flamable or explosive NO NO (YES) NO
Toxic NO NO YES NO
* prEN 378-1 (2003)
11
13. Transcritical Energy Savings
Energy savings of
Mean Annual
transcritical CO2 Temperature
compared to single stage s
•Stockholm 10%
R404A
0 - 5°C
•Copenhagen 9%
•Berlin 3%
•London 4%
5-
10°C
•Paris 0% •Vienna 1%
10 -
•Rom -10% 15°C
•Istanbul -9%
•Madrid -7%
15 -
20°C
14. Transcritical vs. Subcritical
Transcritical & Subcritical CO2
• Copenhagen 9%
Paris 0%•
Seattle 3%• • Buffalo 1% • Rom -10% Sapporo 3%•
Subcritical
CO2 Subcritical
CO2
Cape Town -10%•
Melbourne -4%•
Energy savings of Transcritical & Subcritical CO2
transcritical CO2 compared
to single stage R404A
15. Principal diagram CO2 cascade system with 2 temperature
levels (e.g. supermarket refrigeration)
Pump circulating
system / -7°
C
Direct expansion
/ -20°
C
15
16. Characteristics of CO2 cascade system
• Efficient in all climate areas
• Usage of CO2 lowers the amount of
HFC refrigerant (system charge)
• If combined with NH3 or
Hydrocarbons on upper side of
cascade, 100% ecological solution
• CO2 is practical when used in low
temperature cooling
• Highest pressure in the system is 40
bar, so copper pipelines and
standard components can be used
• 70% - 90% lower consumption of el.
energy for recirculation, comparing
to brine systems
16
17. Experiences
• Mostly good experiences, but larges issues can occur with
dimensioning of pipes, heat exchangers and problems on HT system
• HC or HFC system on HT side
• CO2 on LT and MT (25/40 bar systems)
• Typical system:
-30°C evaporation on LT CO2 system
-10° evaporation on MT CO2 system
C
• CO2 condensation at -10° C
• Direct expansion on LT and pump (or natural) recirculation on MT
• In large systems, CO2 pump uses app. 10% el. energy
17
20. Why CO2 in industrial applications ?
• Faster reaction time
to any temperature change
• Pipelines are much smaller
comparing to brine systems
• Energy consumption for
recirculation is few percentage
comparing to classical systems
20
21. Program for calculating energy savings with CO2 as
secondary refrigerant
www.danfoss.com/COtoo
CO2 calculator helps you estimate energy savings using CO2 as secondary
refrigerant comparing traditional systems with water mixtures
21
22. Energy efficiency comparison between R404A/CO2 cascade
system and conventional R404A i R22 systems in retail
stores
A. Silva(a) , E. Almeida(b) ,
E.P. Bandarra Filho(c)
(a), (b)Bitzer Compressores Ltda , Brazil.
(c)Faculty of Mechanical Engineering – Federal
University of Uberlandia, Brazil
9th IIR Gustav Lorentzen Conference 2010,
Sydney
22
23. Energy efficiency comparison between R404A/CO2 cascade
system and conventional R404A i R22 systems in retail
stores
23
24. Energy efficiency comparison between R404A/CO2 cascade
system and conventional R404A i R22 systems in retail
stores
24
26. CO2 Transcritical Booster
CO2 Trans-critical Booster
• Efficient in mild climates
• One refrigerant
• Controls available today
– Gas-cooler controls
– Receiver pressure controls
• Standstill security
• Oil management solved
• Excellent potential for heat reclaim.
27. CO2 Transcritical Booster Gas cooler
HT compressor
High pressure
regulator
Gas “by-pass”
“by-
valve MT
Expansion
valve
Booster / LT compressor
LT
28. Market Drivers for Refrigerants
1. Legislation
– Tax on refrigerants
– Refrigerant charge
– F-gas
2. Operating cost
– Energy
– Service
– Refrigerant cost
3. Green profile
- Carbon footprint
29. Legislation, Subsidies, & Taxes
Subsidies: Japan, Germany,
Quebec
TAX on F-gases: DK, NO, SE,
etc.
Russia
North America
Europe
Japan
Middle East
Asia
California? Africa
Charge limitations: Denmark, Austria, ….
South America
Australia
Legislation forces the use of natural refrigerants
30. Taxes on refrigerants in Denmark, Sweden and Norway
2010 2011 2010 2011
Refrigerant KR / kg KR / kg € / kg € / kg
HFC-23 (R-23) 400 600 54,1 81,1
HFC-134a (R-134a) 130 215 17,6 29,1
R-404A (HFC-143a/HFC-125/134a) 378 588 51,1 79,5
R-407C (HFC-32/HFC-125/134a) 165 266 22,3 35,9
R-410A (HFC-32/HFC-125) 198 313 26,8 42,3
R-507 (HFC-125/HFC-143a) 385 598 52,0 80,8
http://www.skm.dk/tal_statistik/satser_og_beloeb/184.html
31. Taxes on refrigerants in Slovenia
Company responsible for keeping record about refrigerants, pays after
first installation 5% targeted tax level for 2013.
For refilling of the installation, following taxes apply:
Tax
1.1.2013
GWP € / kg
R404A 3784 93,4 40,5
R134a 1300 93,4 13,9
01.01.2009 01.01.2010 01.01.2011 01.01.2011 01.01.2013
10% 20% 40% 80% 100%
R404A 4,05 8,1 16,2 32,4 40,5
R134a 1,39 2,78 5,56 11,12 13,9
32. Market trends CO2 status Nordic
• Subcritical CO2
– Several hundreds of various types of installations
– more than 10 years of experience but now in decline because of simpler
transcritical systems and high taxes on HFC refrigerants
• Transcritical stores
– 2006 > 5 stores
– 2007 > 50 stores
– 2008 > 150 installations
– 2009 > 300
– 2010 > 500
– 2011 > 700
• Market standard appears to become
1. Cascade MT pump CO2 and LT CO2 DX
2. Transcritical booster systems
Most ambitious is IKEA saying a carbon footprint of 0% !!!
33. Market trends CO2 status Great Britain
The Environmental Investigation Agency releases
Chilling Facts III report ; March 2011
HFC-free refrigeration in UK
– 2008 > 14
– 2009 > 193
– 2010 > 239
TESCO ; HFC-free, 57 in UK, 23 outside UK
Marks & Spencer ; 29 stores by April 2011. Totally HFC-free by 2030
Sainbury ; 2 stores in 2009, 71 stores by March 2011
Morrisons ; hybrid systems in 23 stores
• Tesco, Sainsbury, COOP and many others say reduction of carbon footprint by
20-30 % by 2020
34. Market trends CO2 in Eastern Europe
Poland
Since 2008 several industrial cascade NH3/CO2 plants; capacities 300-600 kW
One supermarket application
Russia
Industrial cascade NH3/CO2 plants ; 2 storage, 2 production, 1 sport facility
Hungary
4 years of experience
In beginning subcritical systems but now transcritical is more attractive
Applications in supermarket and industrial refrigeration
Aprox. 10 subcritical and 40 transcritical systems
35. Future trends
• Today systems build are between 25 and 300 kW
• Future systems will be smaller to cover gas stations and small stores
segment
• Bigger systems will also be a more common application taking over
from ammonia in some cases
• Transcritical CO2 will also be used in large AC systems
36. Large systems
• Netto Central storage facility
vest of Århus (Denmark)
• Total installed capacity
approx 1,5 MW
• Transcritical gas by pass
system
• Heat reclaim 1,5 MW
at 70/40 ºC water
• Start up Q2 2009
37. Large systems
Storage of fruit and vegetables
Måkested Norway:
Booster with gas-by-pass, DX
Capacity: 2 x 400 kW
Evaporation temperature: -10ºC/ -35ºC
Economy: 20 % saving on installation
and approx 20 % saving on energy.
Compared to cascade systems
38. Parken in Copenhagen – AC with DX CO2
Gas by-pass system with DX CO2
3 x 400 kW installed capacity
Evaporation temperature 7-8 ºC
Economy: 20% saving on
installation and 15% saving on
energy compared with high end
HFC chillers
