Refrigeration  &  A/C  Controls   |  1  |  1  

CO2  for  Supermarkets  

Torben  Funder-­Kristensen      Danfoss  Refrigeration  and  Air  Conditioning  Controls  tfk@danfoss.com  

Refrigeration  &  A/C  Controls   |  2  |  2  

Agenda   The  history  of  CO2    Notes  on  CO2    Basic  application  of  CO2  

Subcritical  application  Transcritical  application    

 Top  applications  for  CO2  in  the  Cold  Chain  

Industrial  Refrigeration  Food  Retail  Refrigeration  (incl.  case  study)  

 Trends  for  CO2  in  the  Chinese  market    CO2  Outlook  for  the  future  

 Conclusion  

HFC  (CFC)  HCFC  

NH3  

Refrigeration  &  A/C  Controls   |  3  |  3  DIR-2004-02 - page 3

1850 1993 1960 1920 -1930

The  peak  of  utilizing  CO2  as  refrigerant  

Reinvention  of  CO2-­refrigeration  technology  (G.  Lorentzen)  

Proposal  to  use  CO2  as  a  refrigerant    (A.  Twining,  British  patent)  

One  of  the  first  refrigerants  at  all    Deemed  out  for  decades      Finally  returned  to  play  a  major  role  within  refrigeration  applications  

The  history  of  CO2  

2012

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Notes  on  CO2  

Non-­toxic  and  Low  GWP  

 

Energy  efficient    but  observe  the  limitations  for  outdoor  temperature  and  design  the  system  accordingly  

 

Systems  and  components  have  been  under  development  during  the  last  decade  

 

The  state  of  art  performance  increases  and  maturity  have  not  been  reached  yet  

     

 

Subcritical CO2

Transcritical & Subcritical CO2

Transcritical & Subcritical CO2

Subcritical CO2

Efficiency Limits of Transcritical CO2

Subcritical CO2

Transcritical & Subcritical CO2

Transcritical & Subcritical CO2

Subcritical CO2Subcritical CO2

Transcritical & Subcritical CO2

Transcritical & Subcritical CO2

Subcritical CO2

Efficiency Limits of Transcritical CO2

75 80 85 90 95 100 105 110 115 120Gas cooler pressure [bar]

0.00

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0.75

1.00

1.25

1.50

Ref

riger

atin

g ca

paci

ty [k

W] a

nd C

OP

[-] COP

QE

tE = -10 °C, tSH = 10 KtGC,OUT = 35 °C

OPERATING CONDITION

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CO2  

NH3  R2XX  R4XX  R1XX  

Subcritical  Applications  

First  applications  used  in  IR  and  CR  

 

CO2  used  up  to  approx.  50  pressure    

 

CO2  used  in  cascade  with  another  refrigerant  

 

CO2  used  with  direct  expansion  and  /  or  as  brine  

 

Many  systems  installed  in  especially  EU  

     

 

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CO2  

Only  used  in  northern  climates    

 

Max  pressure  up  to  approx.  120  bar    

 

Two  stage  compression  

 

CO2  used  with  direct  expansion  and  /  or  as  brine  

 

Now  1000+  systems  installed  in  especially  EU.    

     

 

Transcritical  Applications  

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Top  Applications  for  CO2  in  Refrigeration  Cold  Chain  

Industrial  Refrigeration  Safe  fluid,  running  cost  savings,  first  cost  savings,  and  space  savings  

Food  Retail  Cheap  and  safe  refrigerant,  long    term  solution,  lower    running  costs,  

-­  and  space-­heating,    

Transport  Refrigeration  Safe  fluid,  long  term  solution,  cheap  and  safe  refrigerant,  potential  future  carbon  quota  offsetting  

Bottle  Coolers  

alternative  to  R290.  

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CO2  in  Food  Retail  Future  environmental  secured    no  new  phase  down    State  of  the  art  technology    Component  and  system  knowhow  available    CO2  in  cascade  with  HFC/HC/NH3      CO2  in  booster  systems    Globally  applicable    Higher  efficiencies      CO2  systems  show  outstanding  performance  using  heat  reclaim    

Refrigeration  &  A/C  Controls   |  10  |  10  

Food  Retail  System  and  Components  

New  developed  technology  applicable  up  to  140  bar  pressure    Full  program  of  Controls  available  including  supermarket  supervision      Established  and  well  proven  technology      Education  and  training  available  at  Danfoss      

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The  Fakta  Case  Study  

2nd  generation  CO2  system  

3  system  types  compared  R404a  conventional  latest  technology  CO2/CO2  -­  1st  generation  system  CO2/CO2  -­  2nd  generation  system    

 10  stores  comparable  in  each  category    All  stores  located  within  distance  of  150  Kilometers    Running  time  is  12  months      Data  acquisition  on  remote  basis        

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Refrigeration  &  A/C  Controls   |  13  |  13  

CO2  -­  outlook  for  the  future  

Due  to  the  advantages  of  CO2  seen  from  an  energy,  total  cost  and  environmental  point  of  view  Danfoss  foresees  that  CO2  will  become  a  major  global  refrigerant    

 

The  technical  advantages  using  CO2  is  not  yet  fully  exploited  which  means  a  considerable  amount  of  development  will  still  happen  

 

Especially  in  the  field  of  combining  refrigeration  and  heating  purposes  a  high  development  potential  is  foreseen  

 

 

 

Relative sizing of pipes to give the same capacity: R134a R22 CO2 Dry suction line Liquid Line

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Conclusion  

CO2  has  shown  to  be  a  competitive  refrigerant  and  environmentally  benign  in  all  senses  within  IR  and  FR    

CO2  applications  within  IR  and  FR  are  showing  high  growth  rates    

During  the  last  10  years  a  lot  of  development  has  taken  place  and  systems  are  running  very  reliable.    

CO2  systems  needs  special  attention  because  they  are  different  to  HFC  and  alike  systems.    

CO2  refrigeration  systems  in  combination  with  heat  recovery  is  expected  grow  considerably.    

Opportunities  with  CO2  are  far  from  being  exploited.  Here  is  still  a  lot  of  room  for  innovation  

 

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ODP  =  0  (Ozone  depletion  potential)  GWP  =  1  (Global  warming  potential)  Not  flammable  Not  toxic  (EN  378)  Low  viscosity  High  volumetric  cooling  capacity  Small  compressors  Small  suction  lines  

High  pressures  Low  critical  temperature  High  tripple  point  

co2phasechanges128Kbit.wmv

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0,3

0,4

0,5

0,6

0,7

0,8

0,9

-5 5 15 25 35 45 55tc [°C]

Car

not e

ffici

ency

[-]

R717R22R134aR600aR290R410AR507R404AR407CR744

Poor  thermodynamic  efficiency  of  a  refrigerant  can  be  compensated  for  by  increased  efficiency  of  components  or  by  changes  to  the  configuration  of  

the  system.  

|  20  

High Volumetric Cooling Capacity A small volume of refrigerant has a high capacity 5 7 times higher than R22 Smaller line sizes are needed Smaller compressor is needed

High Pressure Refrigerant

1 Kelvin = 1 Bar Effect of line losses is very low

High Density Gas

Heat exchangers become very efficient Low temperature difference between CO2 and air

Relative sizing of pipes to give the same capacity: R134a R22 CO2 Dry suction line Liquid Line

|  21  

SUB-­CRITICAL  

TRANS-­CRITICAL  

TWO-­STAGE  COMBINED  

|  22  

hEVAP   hCOMP  

COP  =  1.90  

COP  =  2.31  

COP  =  2.28  

75 80 85 90 95 100 105 110 115 120Gas cooler pressure [bar]

0.00

0.25

0.50

0.75

1.00

1.25

1.50

Ref

riger

atin

g ca

paci

ty [k

W] a

nd C

OP

[-] COP

QE

tE = -10 °C, tSH = 10 KtGC,OUT = 35 °C

OPERATING CONDITION