1. REFRIGERATION SYSTEMS
ALL - CO2 SUPERMARKET
REFRIGERATION SYSTEMS

2. CO2 REFRIGERATING UNITS
Kyoto protocol and its consequences
Why CO2
State of the art

3. KYOTO PROTOCOL AND EU Kyoto protocol
Came into force from February 16th 2005, Over 160 nations involved
Greenhouse gas emission reduction
Strong influence on refrigeration and air conditioning
EU banishes HFCS, HCFCS, restricts the use of HFCS
Many important nations, such as Australia, Canada and Japan, set funds for HFCS emission reduction
Russia ratified Kyoto protocol on 2004
EU proposal: evolution of regulation 2037/2000
Obligation to perform regular leak test
Reporting duties regarding greenhouse gas emission
Logbooks for control and recharging operations
Phase out R134a in automotive air conditioners from 2014 (probably replaced by CO2)
Several North European countries are moving to natural refrigerants
Danish government applies a 100€ for 1 kg of HFCS in taxes

4. ALTERNATIVES Natural refrigerants: Why CO2 Ammonia NH3
Know how available
Toxic/Flammable
Indirect system required
Water condensation
Hydrocarbons HC
Know how available
Flammable/Explosive
Indirect system required
Reliable for domestic refrigeration
Largely available in nature (GWP=1)
Very low cost respect to traditional refrigerants
High refrigerating capacity
Not toxic/Not flammable
Direct expansion system with heat recovery
Redesign components required
EPTA CHOICE
Carbon Dioxide CO2

5. OUR CONCLUSIONS
Secondary systems aren’t economical choices, especially in LT. A DX concept is needed
The only natural fluid that can be used without harm is CO2

6. PLANT SOLUTIONS
Secondary fluid
system
Centralised CO2
system
MT and LT pack with R404A or NH3 and CO2 as a secondary refrigerant subject to phase change
Direct expansion CO2 LT in cascade with R404A or NH3 MT
Direct expansion CO2 LT and MT with heat realised directly into the atmosphere

7. SECONDARY FLUID SYSTEM
HFC, NH3 or HC
ADVANTAGES
Low pressure in piping
High evaporator efficiency
DISADVANTAGES
CO2 pump
Two refrigerants are used
Pump energy consumption
Plant complexity
Installation costs
CO2

8. HYCOOL®
Product specification Following data is at 20°CComposition: Potassium formate 30-50%, deionised water and corrosion inhibitor
Appearance: Clear fluid, insignificant smell
Freezing point: -20 to -50°C
Density: 1194 – 1348 kg/m³
Dynamic viscosity: 1,8 – 2,6 mPas (cP)
Thermal conductivity: 0,50 – 0,56 W/mK
Specific heat capacity: 2,5 – 3,0 kJ/kgK
Boiling point: 105 – 115°C at atmospheric pressure
pH: 10,6 – 11,4
Refractive index: 1,364 – 1,385
Surface tension: 78,5 mN/m för HYCOOL 20
Thermal expension coefficient: 3-4 • /K
Vapour pressure: 1,3 – 2,0 kPa Electrical conductivity: 210 – 240 mS/cm
Flashpoint: Non-flammable
Miscibility with water: Complete

9. Secondary Fluid (Propylene,etc..)
CASCADE SYSTEM
ADVANTAGES
HFC, NH3 or HC
Consolidated know-how
Low pressure in piping
DISADVANTAGES
Three fluids used
LT not autonomous
Plant complexity
High installation costs
CO2
Secondary Fluid (Propylene,etc..)

10. DIRECT EXPANSION SYSTEM/1
High pressure CO2 compressors NT LT
CO2
CO2

11. DIRECT EXPANSION SYSTEM/2
ADVANTAGES
Completely “green”, only CO2
Simple system
Competitive energy efficiency especially in cold climates
Reduced CO2 charge
DISADVANTAGES
Relatively high pressure in piping
Efficiency somewhat lower than conventional dx systems in hot climates without special arrangements
CO2

12. DESIGN CONCEPTS
With CO2 systems the following design concepts should be used:
To operate at the lowest discharge pressure permitted by ambient temperature (or cooling medium available)
 to operate in subcritical conditions when ambient temperature is < 20°
To use subcooling when operating at subcritical conditions
To use hybrid cooling when operating with high ambient temperature (> 30° C), the mass flow of water needed is very low
To use a 2 stage concept in low temperature (- 35°C) discharging the heat directly to ambient

13. COP - MEDIUM TEMPERATURE
CONDITIONS
Evap. temp. -10°C
Temp. evap. out -5°C
Subcooling 3 K in subcritical
Approach 3 K in transcritical
Calculation based on the monthly medium-day temperature
Minimum condensing temperature +25°C (R404A), +15°C (CO2)
HER based on indoor temperature

14. MT AIR COOLED
Ambient temperature

15. COP - LOW TEMPERATURE CONDITIONS Evap. temp. -35°C
Temp. evap. out -30°C
Efficiency of S/L HX 60%
Subcooling 3 K in subcritical
Approach 3 K in transcritical
Minimum condensing temperature +25°C (R404A), +15°C (CO2)
Calculation based on the monthly medium-day temperature
HER based on indoor temperature

16. LT AIR COOLED
Ambient temperature

17. ENERGY CONSUMPTION CONDITIONS MT 120kW LT 20kW Based on Bruxelles TRY
HER weighted upon internal thermal load
Minimum condensing temperature +25°C (R404A), +15°C(CO2)

18. Customization required to gain efficiency in hot climate countries
COP of MT and LT CO2 unit as a function of ambient temperature
Customization required to gain efficiency in hot climate countries

19. EPTA RANGE
Medium Temperature

20. EPTA RANGE
Low Temperature

21. EPTA RANGE
Dimensions of 2 compressors units

22. EPTA RANGE
Three-compressors NT cooling pack, water gas cooling

23. EPTA RANGE

24. AIR GAS COOLER

28. SAFETY: PRESSURE/1
Design pressure of units is 120 bar high side and 60 bar low side
Units are CE marked
Evaporators of cabinets and cold rooms are designed for 60 bar
Multipipe distribution system allows the use of small piping: 18 mm OD for about 20 kW at - 10°C, with pressure drop less than 100 kPa ( 1,5 K) in suction line for 40 m run
Max working pressure of annealed copper pipe up to 18 mm is about 60 bar. Hard copper and joints can withstand even higher pressure
Relief valves on unit manifolds and vessels protect piping and evaporators in the event of power supply failure for an extended period (typically many hours)

29. SAFETY: PRESSURE/2 Opportunity: only main manufacturers and customers
PED compliance: new components by commercial refrigeration usual suppliers and industry suppliers are specifically designed (vessels, manifolds, filters,…)
Reliability: there are no technical reasons in the medium term for substantial differences between HFCs plants and carbon dioxide plants
Industrialization: high quality level over the whole supply and production chain

30. TOXICITY Potential risks only in the machine room (leak detector)
Over two times lower than the value that causes a breathing acceleration
Potential risks only in the machine room (leak detector)
Very low risks in the market area

31. CASE HISTORY/1 2002: First supermarket Cascade Chillers Heat recovery
Transcritical air condensed
Transcritical water condensed
Cascade

32. CASE HISTORY/2 COSTAN: 2002: First supermarket, 50 kw MT + 38 kw LT
Reliability: LT and MT refrigerating units are indipendent
2004: 180kw MT + 76kw LT
COSTAN:
2004: 160kw + 34kw
Transcritical MT + cascade subcritical LT
LINDE:
Complexity, criticity, reliability

33. CONCLUSIONS CO2 is a natural fluid, non toxic and non flammable
A single “green” fluid for all the refrigeration system
Simple system
Energy efficient, especially in cold climates
Reduced CO2 charge
Reduced pipe diameters, low installation cost
Technically the best solution available today,
with further improvements under development

34. REFRIGERATION SYSTEMS
ALL - CO2 SUPERMARKET
REFRIGERATION SYSTEMS