DESIGN AND SAFETY STANDARDS FOR HC REFRIGERANTS AND CO2  

Dr. Ignat Tolstorebrov Brussels, May 29th 2015

Faculty of Engineering Science and Technology Department of Energy and Process Engineering

IN “BREAKING OUT THE BARRIERS FOR THE WIDESPREAD USE OF NATURAL

REFRIGERANTS: NXTHPG PROJECT”  

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Agenda: 1 Main safety standards 2 Determination of refrigerant charge 3 Allowable pressure 4 Other requirements

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1. Safety standards IEC 60335-2-24:2012 Household and similar electrical appliances - Safety - Part 2-24: Particular requirements for refrigerating appliances, ice-cream appliances and ice makers IEC 60335-2-34: 2012 Household and similar electrical appliances - Safety - Part 2-34: Particular requirements for motor-compressors IEC 60335-2-40:2013 Household and similar electrical appliances - Safety - Part 2-40: Particular requirements for electrical heat pumps, air-conditioners and dehumidifiers IEC 60335-2-89:2012 Household and similar electrical appliances - Safety - Part 2-89: Particular requirements for commercial refrigerating appliances with an incorporated or remote refrigerant unit or compressor EN 378:2008+A2:2012 Refrigerating systems and heat pumps – Safety and environmental requirements- Parts 1-4 ISO 5149:2014 Mechanical refrigerating systems used for cooling and heating – Parts 1-4

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1. Safety standards Safety standards limit CO2 and HC in following regions: 1.  Area of application of system 2.  Refrigerant charge – the most important parameter 3.  Working temperatures 4.  Allowable pressures 5.  Safety devices

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2. Determination of a refrigerant charge.

Refrigerant  class  

(group)  

Occupancy  category  

Type  of  system  

(dir/indir)  

Refrigerant  charge  

Loca;on  area  (volume)  

Type  of  the  system  (HP  or  

REF.)  

Loca;on  of  system’s  elements  

Proper;es  of  refrigerant  

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2. Determination of refrigerant charge: properties of refrigerants

#     Name   LFL,  kg  m-­‐3   PL,  kg  m-­‐3  ATEL/ODL   Autoigni:on  

temperature,  °C  

R50   Methane   0.032   0.006   N.D.   645  R170   Ethane   0.038   0.008   0.008   515  R1150   Ethylene   0.036   0.007   N.D.   N.D.  R290   Propane   0.038   0.008   0.09   470  R1270   Propylene   0.047   0.008   0.002   455  R600   Butane   0.048   0.0086   0.002   365  R600a   Isobutane   0.038   0.011   0.006   460  R601   Pentane   0.035   0.008   0.003   N.D.  R601a   Isopentane   0.038   0.008   0.003   N.D.  The  values  were  taken  in  accordance  with  EN  378-­‐1:2008  (F.3.1.)/  ISO5149-­‐1:2014  gives  a  bit  different  values  

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2. Determination of refrigerant charge: Domestic applications of systems IEC  60335-­‐2-­‐24:2010+A1:2012,                                                      IEC  60335-­‐2-­‐40:2013  

IEC   60335-­‐2-­‐24:2010+A1:2012   regulates  the  maximum  charge  of  the  refrigerant  in  the   refrigera;ng   appliances   and   ice  makers   for   households   and   similar   use.  The   maximum   refrigerant   charge   is  limited  by  0.15  kg  irrespec;vely  from  the  area   of   the   occupancy.   The   system  should  be  factory  sealed  

IEC   60335-­‐2-­‐40:2013   regulates   the   refrigerant  charge   in   heat   pumps,   sanitary   water   heat  pumps ,   a i r -­‐ c ond i ;one r s   ( A /C )   a nd  dehumidifiers  .  The  methods  of  the  es;ma;on  of   the   allowable   charges,   which   are   listed   in  IEC   60335-­‐2-­‐40:2013,   are   similar   to   those  w h i c h   a r e   i n t r o d u c e d   i n   E N  378-­‐1:2008+A2:2012   for   A/C   and   heat   pumps  for  human  comforts.  

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2. Determination of refrigerant charge: types of occupancies

Categories   Restric:on   Examples  General  

occupancy  A  

Low  

Hospitals,   courts,   schools,  s u p e r m a r k e t s ,   h o t e l s ,  restaurants  etc.  

Supervised  occupancy  

B  Medium  

Business  or  professional  offices,  laboratories,   places   for   general  manufacturing   and   where  people  work.  

Authorized  occupancy  

C  High  

Manufacturing   facili;es,   cold  stores,   non-­‐public   area   in  supermarkets.  

Standards:  EN  378-­‐1:2008  ISO  5149-­‐1:2014    

Requirements  to  ref.  charge  

Strict  

So`  

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2. Determination of refrigerant charge: location of system’s elements ISO  5149-­‐1:2014  gives  be]er  and  more  clear  classifica:on  of  the  same  loca:on    types  as  EN  378-­‐1:2008  Class  type   Notes  Class  I   Mechanical  equipment  located  within  occupied  space.  Class  II   Compressor  in  machinery  room.  Coil  heat  exchanger  and  

pipework  can  be  located  in  occupied  space.  Class  III   Machinery  room  or  open  air.  Special  requirement  for  organiza;on  

of  machinery  room  Class  IV   Ven;lated  enclosures.  All  parts  of  the  system  should  be  inside  the  

enclosure.  Extra  requirements  for  size  and  ven;la;on.  (This  loca;on  is  applied  only  for  A/C  and  human  comfort  heat  

pumps  in    EN378-­‐1:2008)  

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2. Determination of refrigerant charge: class of refrigerants

Toxicity class: A – lower toxicity, do not have effect on people who may exposed to it day after day at a refrigerant concentration 400 ppm or above. CO2 and HC – belong to this group. B – higher toxicity, do not have effect on people who may exposed to it day after day at a refrigerant concentration below 400 ppm.

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2. Determination of refrigerant charge: class of refrigerants Flammability class (EN 378-1:2008) 1 – no flame propagation, refrigerant does not show flame propagation when testes at 60 ºC, 1 atm. CO2. 2 – lower flammability, exhibits flame propagation when tested at 60 ºC, has LFL≥3.5 Vol%, has a heat of combustion < 19.000 kJ / kg. (!extra 2L class is cited in ISO817! The difference is only in flame velocity) 3 – Higher flammability, exhibits flame propagation, LFL≤3.5 Vol%, heat of combustion is >19.000 kJ/ kg

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2. Determination of refrigerant charge: class of refrigerants

CO2  

HC  

A1  

A3  

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2. Determination of refrigerant charge: methods When the class of refrigerant, type of occupancy and system type is clear, the refrigerant charge for CO2 and HC is a function of area of room (occupancy). For HC, EN 378:2008 ISO 5149:2014 and apply different requirements for refrigeration systems and for A/C and human comfort HP.

Charge  R290  In  freezer    

Charge  R290  A/C  system  

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2. Determination of refrigerant charge: human comfort heat pumps «Cap» factor is used to limit the maximum allowable charge (does not apply for CO2): Mc=X*LFL Where X depends on type of A/C system (X=4, 8, 26 or 130). LFL – is a tabular value. The charge below Mc should satisfy some math. dependence, for example:

𝑀=2.5∗𝐿𝐹𝐿↑5∕4  ∗ℎ↓𝑜 ∗𝐴↑1∕2    

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2. Determination of refrigerant charge: other systems «Cap» factor is also used to limit the maximum allowable charge. It depends only on type of occupancy and location of system’s elements. No “Cap” factor for CO2. Class A – from 1.5 to 5 kg (From 1 kg ISO 5149:2014) Class B – from 2.5 to 10 kg Class C – from 10 to no restrictions.

𝑀=PL∗𝑉𝑟𝑜𝑜𝑚  (for  HC  and  CO2)  

EN  378-­‐1:2008   ISO  378-­‐1:2008  𝑀=0.2∗𝐿𝐹𝐿∗𝑉𝑟𝑜𝑜𝑚  (for  HC)  𝑀=Toxicity∗𝑉𝑟𝑜𝑜𝑚  (for  CO2)  

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3. Allowable pressure EN 378-2:2008 and ISO 5149-2:2014 Pressure is determined by taking into account: •  Maximum ambient temperature; •  Possible presence of non-condensable gases; •  Setting of any pressure relief device; •  Method of defrosting; •  Application;  Method  1:  The  PS  is  determined  by  designer,  when  calcula;ons  should  be  verified  by  tes;ng  (The  preferable  method).    Method  2:  The  minimum  values  of  the  maximum  allowable  pressure  can  be  determined  by  the  minimum  specified  temperature  (does  not  work  for  trans-­‐cri;cal  systems)

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3. Allowable pressure Pressure Equipment Directive (PED) 97/23/EC. Diagram for HC. The type of pressure vessel is the question of price.

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Diagram for CO2.

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4 Other requirements Temperature: The hot surfaces should not reach the temperature within 100 K of the autoignition temperature of refrigerant Strength test for elements: EN 378-2:2008, EN 60335-2-34:2012, ISO 5149-2. Refrigerant pressure indicators: HC system with charge over 2.5 kg Electric components: clause 20 IEC 60079-15:2010, devices, which a suitable for Zone 2, 1, 0 (IEC 60079-14:2008) Detectors: EN 378-3:2008, in machinery room if the system charge is greater than 25.0 kg. Alarm limit =0.25 LFL

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Conclusions: •  Relatively high restriction for HC as refrigerants,

especially for their charges; •  Restrictions are used for one installation, thus several

devises can cover the demand in heat, cold etc. •  Effective systems, which are compact, are required. •  CO2 has less restriction, when compared with HC. •  NO «cap» factors and higher refrigerant charge. •  High operating pressure creates problem with class of

pressure vessels, this can be avoided by installation of several receivers.