Hydrocarburos Refrigerantes

Características,

ventajas, aspectos de seguridad, aplicaciones

Rolf Huehren

Senior Consultant

rolf.huehren@proklima.net

History of Refrigeration

In 1834, Jacob Perkins, an American, developed a closed refrigeration system (vapour compression circuit) using liquid expansion and then compression to maintain the cooling effect.

He used Ether as refrigerant, in a hand- operated compressor, a water-cooled condenser and an evaporator in liquid cooler. Patented 1835 as Ether-ice-machine.

Unfortunately some machines exploded because of the formation of highly explosive Peroxide (Ether in reaction with Oxygen)

Refrigerants – historical development

Ozone Depleting Substances (ODS): Artificially induced substances that deplete the ozone layer (→ earth’s protection from UV-rays is reduced).

Naturally occurring substances with low environmental impact, i.e. no ODP and low GWP.

No Ozone Depletion Potential (ODP), but high Global Warming Potential (GWP).

Sorce: SECOP

Hydrocarbon (HC) History and Future

1993 launch of the Greenfreeze refrigerator, developed by Greenpeace in cooperation with East German manufacturer Foron (formerly VEB dkk Scharfenstein), proving that R600a & R290 , although flammable, caused no problems in a household refrigerator.

The campaign from Greenpeace has put so much pressure on the traditional manufacturers (Bosch-Siemens, Liebherr, Miele, AEG, Electrolux, Bauknecht) that they decided to accelerate the introduction of R600a and to phase out the recently introduced R134a!.

Also in 1993 Danfoss Compressors (Secop) introduced compressors for R600a.

Today more than 700 million domestic refrigerators globally use R600a. By 2020, 75% of the global production will be based on R600a.

Hydrocarbon (HC) Characteristics

Chemically speaking, a hydrocarbon (HC) is an elementary compound of hydrogen and carbon which occurs naturally and is found in large concentrations in crude oil.

Used as a modern refrigerant, non-toxic hydrocarbons are an eco-friendly alternative to the CFC/HCFC/HFC fluorocarbons linked to ozone damage and climate change.

In addition to their environmental benefits, hydrocarbons are a cost-saving option for heating/cooling and also for freezing.

The features of a HC system (lower condensing point, positive thermodynamic attributes, and superior COP [Coefficient of Performance]) act in combination to optimize energy-efficient operation.

As an illustration, the use of propane (R290) as an air‐conditioning replacement for an HCFC/HFC system would return a minimum GHG saving of about 80 percent

Hydrocarbon (HC) Characteristics

A common replacement for fluorocarbons (now lacking green credentials), HCs substitutes are compatible with oils and components found in many existing systems.

They can be purchased more cheaply and also offer superior energy efficiency, reflected in more-affordable running costs.

Though HCs are flammable, propane (R290) is in general used for cooking and heating, and thus the necessity for the application of standard practices for the safe handling and deployment of such materials is recognized and accepted by all users.

Assisted by the cheap availability of HCs produced as a by‐product of gas and oil hydrocarbons have proved to be viable replacements for fluorocarbons and other environmentally harmful refrigerants.

HC Application Ranges

RHPAC = Refrigeration, Heat Pumps, Air- Conditioning Source: adapted from Mayekawa

Classification of HC refrigerants

A “higher” classification (i.e. toxicity class B instead of class A, and flammability class 3 instead of class 1) means:

the refrigerating system has more demanding design requirements, in order to handle the higher risk represented by the refrigerant.

Natural Refrigerants Characteristics

Approximate auto-ignition temperatures

R22 635 ºC

R12 750 ºC

R134a 743 ºC

R290 470 ºC

R600a 460 ºC

HFC-1234yf 405°C

Oil 222 °C

Chemical refrigerants strongly and negatively affect health and the environment When HCs burn, they

produce carbon and steam. When chemical refrigerants

(such as HFCs and HCFCs) burn, they ALL produce toxic substances (e.g. hydrofluoric acid).

Specifying the right quality of the refrigerant

Important Safety Aspects

Due to their physical properties and high flammability, refrigerating systems using hydrocarbon refrigerants require special safety precaution measures.

The electrical design plays a central role for safety and exceeds the requirements for the use of non-flammable refrigerants.

Careful consideration of the design and construction of HC refrigeration systems and their installations is essential to achieve maximum safety.

~2 % ~10%

Oxygen 0 % to 100 %

HC refrigerant critical

region to ignite Gas /

Oxygen Mixture

Safety rules for alternative refrigerants

Standard Equipment type Coverage

EN 378 Commercial and industrial

Components, safety devices, system design, location, charge

size limits, refrigerant classification, installation site,

maintenance ISO 5149 Commercial and

industrial

60335-2-24 Domestic fridges and freezers

Marking, pressure testing, electrical

60335-2-40 Factory built a/c and heat pumps

Marking, pressure testing, maintenance, electrical, charge

limits

60335-2-89 Factory built commercial

fridges

Marking, pressure testing, electrical

Extract on Standards

In general all system designs of the electrical equipment should comply with:

product standard of the EN 60335 series, or

EN 60204-1 (Safety of machinery) and for electronically controlled systems related with EN ISO 13849-1 and / or EN 62061 (Safety-related parts of control systems)

Additionally for flammable refrigerants:

EN 378-2:2017-3

6.2.14 Protection against fire and explosion hazards

6.2.15 Requirements for ventilated enclosures where applied for A2(L), B2(L), A3 and B3 refrigerants as defined in EN 378-1:2017-3 Annex C1, C2 (charge limits)

Electrical requirements: relevant standards

Importance of Standards

New Product /

Installation

Standard

Available?Permit use?

Accept

responsibility

Do not use Use

YES

NO

NO

NO

YES

YES

• Provide indication of „best practice“

• Although rarely mandatory, give „safety net“ for new options

• Certain refrigerants have significant different safety characteristics

Before addressing safety aspects directly, initial task to minimise refrigerant charge Primarily target condenser; HX design. With some effort, can approach <20% of HCFC/HFC charge.

Safety – risk analysis approach

Safety – improved system tightness

Improve system tightness Strength pressure test. Leak tightness test.

Additional tests • Mechanical impact, vibration,

resonance, cycling, drop, corrosion, long-term run

Tightness standard ISO 14903. Additional design/ construction

• Prevention of frost damage, thermal cycling, etc)

Safe design working – Risk Assessment

19 HEAT GmbH – Habitat, Energy,

Application & Technology

Risk analysis (identifying the processes) and risk assessment (characterisation, quantification) is useful for aiding safe application of flammables.

Assists in identifying critical flammability hazards through rational understanding of flammability risks.

Implies thorough evaluation of variables. Imposes systematic checking of influencing factors. Highlights areas needing improvement in safe design.

Human behaviour has greatest influence on risk of ignition.

Business as usual (for HCs) as with “Safety Refrigerants” may lead to fatal accidents.

Risk of ignition is function of probability of leak; size of flammable cloud; duration of flammable cloud; presence of sources of ignition.

During servicing higher probability of leakage (breaking into system); more refrigerant to leak (e.g., cylinders) more sources of ignition (service equipment) etc.

Overall, risk of fire 10× to 1000× higher during servicing! > Therefore, essential to focus on reducing risk whilst installation and servicing.

Safe working & servicing practices

Important Servicing Issues

When breaking into the HC refrigerant circuit e.g. component replacement Use of appropriate gas detector. Use of appropriate PPE. HC refrigerant recovery, venting, safe burning. Sufficient circuit evacuation (HC residues in oil). Inerting (flushing) with OFDN*. Cold “Cutting Out” of system parts before

considerations for un-brazing. During brazing, inerting with OFDN* (*oxygen free dry nitrogen) .

Outdoor side

IDU

ODU

Indoor side

Cylinder to collect oil

Hose

Diffuser

1 m

3 m

Refrigerant venting instead of recovery

Charge system limit for venting in capillary systems ≤ 500 g !

While removing the refrigerant from the system, oil should be separated.

Prevention of Accidents

European Standard EN 13313 describes the minimum education level and what topics to be knowledgeable

Training centres and institutes around the world can approve the skills to be achieved

Technicians need to be trained at least in handling the refrigerants they are to work with

Service technicians that are on call need to know more than installation only technicians

For doing leak check only you can be trained for this in specific

Accidents will happen (as with ALL other refrigerants) but we can try to avoid them! Good Training and Best Practices are „Key Elements“ for a safe

HC application environment and all RACHP sectors

Ease of application of natural refrigerants

Air conditioning

Refrigeration

Residential

Domestic RetailStorage and food

processing

Commercial

Self-

contained

Non-ducted

single splitDucted split Chillers RooftopMultisplit

IntegralsCondensing

units (cabinets)

Fridge/freezers

Integrals

Non-ducted

single splits

CentralisedCondensing

units (coldstores)

Centralised

ChillersDirect

distributedChillers

Direct distributed

Central split

Air- Conditioners – Split Type and Factory Sealed

Air- Conditioners – Split Type and Factory Sealed

Several manufacturers in Europe, China, India, Australia primarily using R290.

Charge sizes up to 1 kg/7 kW cooling capacity

• Very high efficiency.

Reversible systems available.

Major shift to R290 underway in China, availability will improve over time.

Safety aspects designed to EN 60335-2-40.

Cost of R290 systems same as HFC products.

Energy consumption R290 gives about 5-10% higher efficiency than HFC options.

Plug-in chillers and freezers > Examples

Many commercial cabinets with R290, R1270, R600a

• End users report 5 – 15% lower energy use.

Numerous manufacturers within Europe, Japan, Central America, Southern Africa, China, SE Asia, etc.

Two general categories

• Movable type appliances with charges up to 150 g.

• Fixed appliances charges up to 1.5 kg.

Safety aspects

• Designed to EN 378.

• Charge size up to 150 g of R290.

Cost of R290 systems same as HFC products.

290 provides lower noise levels, operates efficiently up to +43°C ambient.

Plug-in chillers and freezers > Examples

Condensing Units (remote controlled refrigerating systems)

Condensing Units (remote controlled refrigerating systems)

Small condensing units.

Range of R290 condensing units

• Smaller capacity range.

Safety aspects

• Designed to safety standards.

• May require gas detector/alarm.

Modular units

• Package with entire system.

• Small charge size.

Safety aspects

• Designed to EN 378/EN 6035-2-89

High efficiency

Chiller

e.g. York/JCI / Euroklimat • Air-cooled chillers

Safety aspects • Designed to EN 378; up to 25 kg of R290

Cost marginally more than HFC products, but with “green premium”

R290 gives ~15% higher COP than R407C, R410A products

Centralised supermarket systems

Conventional Alternative

Type

Direct expansion,

multi-compressor

pack

Cascade

Indirect (liquid sec)/

cascade

Indirect (phase-change

sec)/ cascade

Trans-critical booster

Distributed water cooled

Medium temp

R404A, R507A, R407F

Lower GWP HFC, (HC-290, HC-

1270)

HC-290, HC-1270, R-717,

brine

HC-290, HC-1270, R-717,

CO2 R744

HC-290, HC-1270, R-717,

brine

Low temp R404A, R507A,

R407F R744 CO2 CO2 R744

HC-290, HC-1270

Options for different systems

Indirect (Secondary Loop) HC System

09/10/2017

Integral System Supermarket

Refrigeration System Heating & Cooling

Ventilation System Demand Controlled

Air Quality

Plus Cooling

Minus Cooling

LIDL Co. Germany

No ozone damage implications Significantly reduced GHG emissions Low GWP ratings, and thus low global

warming effects Greater energy efficiency Easy implementation Production conversion requires minimal

investment Good cost effectiveness of appliances and

refrigerating systems

In summary, advantages of HC technologies are:

Thank you for your attention!