DESIGN AND SAFETY STANDARDS FOR HC REFRIGERANTS AND CO2 IN “BREAKING OUT THE BARRIERS FOR THE WIDESPREAD USE OF NATURAL REFRIGERANTS: NXTHPG PROJECT”
Dr. Ignat Tolstorebrov Brussels, May 29th 2015 Faculty of Engineering Science and Technology Department of Energy and Process Engineering
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, airconditioners 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 3
1. Safety standards Safety standards limit CO2 and HC in following regions: 1. 2. 3. 4. 5.
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Area of application of system Refrigerant charge – the most important parameter Working temperatures Allowable pressures Safety devices
2. Determination of a refrigerant charge. Refrigerant class (group) Loca;on area (volume)
Occupancy category Type of the system (HP or REF.)
Proper;es of refrigerant 5
Type of system (dir/indir) Loca;on of system’s elements
Refrigerant charge
2. Determination of refrigerant charge: properties of refrigerants ATEL/ODL
Autoigni:on temperature, # Name LFL, kg m-‐3 PL, kg m-‐3 °C N.D. 645 R50 Methane 0.032 0.006 0.008 515 R170 Ethane 0.038 0.008 N.D. N.D. R1150 Ethylene 0.036 0.007 0.09 470 R290 Propane 0.038 0.008 0.002 455 R1270 Propylene 0.047 0.008 0.002 365 R600 Butane 0.048 0.0086 0.006 460 R600a Isobutane 0.038 0.011 0.003 N.D. R601 Pentane 0.035 0.008 0.003 N.D. R601a Isopentane 0.038 0.008 The values were taken in accordance with EN 378-‐1:2008 (F.3.1.)/ ISO5149-‐1:2014 gives a bit different values 6
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
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IEC 60335-‐2-‐40:2013 regulates the refrigerant charge in heat pumps, sanitary water heat p u m p s , a i r -‐ c o n d i ; o n e r s ( A / C ) a n d 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.
2. Determination of refrigerant charge: types of occupancies Strict
Supervised occupancy B Authorized occupancy C 8
Restric:on Low
Medium
High
Examples Hospitals, courts, schools, s u p e r m a r k e t s , h o t e l s , restaurants etc. Business or professional offices, laboratories, places for general manufacturing and where people work. Manufacturing facili;es, cold stores, non-‐public area in supermarkets.
Requirements to ref. charge
Categories General occupancy A
So`
Standards: EN 378-‐1:2008 ISO 5149-‐1:2014
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 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 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)
Class IV
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Notes
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. 10
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 11
2. Determination of refrigerant charge: class of refrigerants
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CO2
A1
HC
A3
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 13
Charge R290 A/C system
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 14
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. EN 378-‐1:2008
𝑀=PL∗𝑉𝑟𝑜𝑜𝑚 (for HC and CO2)
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ISO 378-‐1:2008
𝑀=0.2∗𝐿𝐹𝐿∗𝑉𝑟𝑜𝑜𝑚 (for HC) 𝑀=Toxicity∗𝑉𝑟𝑜𝑜𝑚 (for CO2)
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
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Pressure Equipment Directive (PED) 97/23/ EC. Diagram for HC. The type of pressure vessel is the question of price.
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 19
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. 20
