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ALL - CO 2 SUPERMARKET REFRIGERATION SYSTEMS. CO2 REFRIGERATING UNITS Kyoto protocol and its consequences Why CO2 State of the art.

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Presentation on theme: "ALL - CO 2 SUPERMARKET REFRIGERATION SYSTEMS. CO2 REFRIGERATING UNITS Kyoto protocol and its consequences Why CO2 State of the art."— Presentation transcript:

1 ALL - CO 2 SUPERMARKET REFRIGERATION SYSTEMS

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

3 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 HFC S in taxes Kyoto protocol Came into force from February 16 th 2005, Over 160 nations involved Greenhouse gas emission reduction Strong influence on refrigeration and air conditioning EU banishes HFC S, HCFC S, restricts the use of HFC S Many important nations, such as Australia, Canada and Japan, set funds for HFC S emission reduction Russia ratified Kyoto protocol on 2004 KYOTO PROTOCOL AND EU

4 Natural refrigerants: Why CO 2 Ammonia NH 3 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 CO 2 ALTERNATIVES

5 OUR CONCLUSIONS Secondary systems arent economical choices, especially in LT. A DX concept is needed The only natural fluid that can be used without harm is CO 2

6 PLANT SOLUTIONS 2Direct expansion CO 2 LT in cascade with R404A or NH 3 MT 3Direct expansion CO 2 LT and MT with heat realised directly into the atmosphere 1MT and LT pack with R404A or NH 3 and CO 2 as a secondary refrigerant subject to phase change Secondary fluid system Centralised CO 2 system

7 SECONDARY FLUID SYSTEM ADVANTAGES Low pressure in piping High evaporator efficiency DISADVANTAGES Two refrigerants are used Pump energy consumption Plant complexity Installation costs HFC, NH 3 or HC CO 2 CO2 pump

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 10 -4 1/K Vapour pressure: 1,3 – 2,0 kPa Electrical conductivity: 210 – 240 mS/cm Flashpoint: Non-flammable Miscibility with water: Complete

9 CASCADE SYSTEM ADVANTAGES Consolidated know-how Low pressure in piping DISADVANTAGES Three fluids used LT not autonomous Plant complexity High installation costs HFC, NH 3 or HC CO 2 Secondary Fluid (Propylene,etc..)

10 DIRECT EXPANSION SYSTEM/1 CO 2 High pressure CO 2 compressors CO 2 NTLT

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

12 DESIGN CONCEPTS With CO 2 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 (CO 2 ) 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 (CO 2 ) 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(CO 2)

18 COP of MT and LT CO 2 unit as a function of ambient temperature Customization required to gain efficiency in hot climate countries

19 Medium Temperature EPTA RANGE

20 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

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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 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 SAFETY: PRESSURE/2

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

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

32 CASE HISTORY/2 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 CO 2 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 CO 2 charge Reduced pipe diameters, low installation cost Technically the best solution available today, with further improvements under development

34 ALL - CO 2 SUPERMARKET REFRIGERATION SYSTEMS


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