GWP is reason #4 why HFO Refrigerants are a strong alternative to ammonia in mild freezing applications: GWP
Food and beverage companies that need a mild freezing cooling system are increasingly moving away from traditionally used NH3 (ammonia) turning to HFO (Hydrofluoro-olefin) refrigerants. They improve sustainability, boost performance, and significantly reduce costs.
Sustainable companies have sustainability targets and cannot neglect the Global Warming Potential (GWP) of refrigerant fluids when selecting the most appropriate chiller system.
IDEAL REFRIGERANT PROPERTIES
The ideal refrigerant is non-toxic, non-flammable, non-explosive, non-corrosive, environment-friendly, inexpensive, easy to produce and handle and with good thermodynamic properties operating at low pressures.
HFO refrigerants meet these criteria. They have zero ODP (Ozone Depletion Potential) and low GWP (Global Warming Potential). R1234ze is a synthetic HFO refrigerant rather than a natural refrigerant like ammonia, has a GWP value below 1, lower than the CO2 natural refrigerant and doesn’t create TFA (Trifluoroacetic Acid). Ammonia has a GWP of zero. The two fluids are very comparable from this perspective.
HISTORY AND REGULATION OF REFRIGERANTS
The first commercial refrigerants used toxic or flammable gases, such as ammonia, methyl chloride, or propane that could result in fatal accidents when they leaked. Non-toxic and non-flammable refrigerants were later developed: chlorofluorocarbon (CFC) gas known as R-12, hydrochlorofluorocarbon (HCFC) commonly R-22 and hydrofluorocarbon (HFC) refrigerants. These refrigerants were frequently used for industrial purposes as they delivered a high level of safety and efficiency combined with low installation costs. Most of these common refrigerants are greenhouse gases that contribute to global warming and may deplete the ozone layer when leaked to the atmosphere.
The Montreal Protocol in 1987 and the Kyoto Protocol in 1997 resulted in a shift to refrigerants with lower environmental impact. In the EU, regulations came into force in 2002 banning the use of ozone-depleting HCFC refrigerants such as R-22 in new systems.
EU F-gas regulations came into force in 2015 to reduce emissions of fluorinated greenhouse gases (F Gases) through phase-down quotas, bans and maintenance requirements.
These regulations and market demand for more environmentally friendly solutions have driven much innovation in HVAC temperature control with many new refrigerants such as R-454b and R-513a.
REFRIGERANT SAFETY CLASSIFICATIONS
Refrigerants are categorised according to their toxicity and flammability. There are two classes for toxicity; lower toxicity (Class A) where toxic concentrations are less than or equal to 400 parts per million (PPM) by volume and higher toxicity (Class B).
There are four classes of flammability: 1, 2L, 2 or 3. Class 1 is for refrigerants that show no flame propagation at 140°F (60°C) ranging to class 3 highly flammable. The purpose of the 2L subclass is to reflect the lower flammability properties of the new low-GWP refrigerants, such as HFOS (hydrofluoroolefins), like R-1234yf and R-1234ze.
ODP AND GWP
All refrigerants have an ODP (Ozone Depletion Potential) and a GWP (Global Warming Potential) ratings. The ODP is the relative amount of degradation to the ozone layer.
GWP (Global Warming Potential) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (CO2). GWP is a measure of how environmentally detrimental refrigerants can be relative to C02 which has a GWP of 1.0.
TRANE REFRIGERANT DEVELOPMENT
Trane has vast experience in designing products operating with low-GWP refrigerants. The entire portfolio of screw compressor and high-speed centrifugal compressor chillers is already available with low-GWP refrigerant alternatives such as R-1234ze, R-515b and R-513a. Trane entire portfolio of scroll units has been moved to R-454B as the lowest GWP value option to replace R-410a whilst maximising high-efficiency operation. Specifically compared to ammonia systems, Trane chillers use refrigerants that are non-toxic, require easier maintenance, have a lower first cost and low GWP.
KEY TERMS DEFINED
ODP – Ozone Depletion Potential – degree to which a substance can degrade the ozone layer; all measurements relative to a similar mass of CFC-11, which is indexed at 1.0.
GWP – Global Warming Potential – degree to which a greenhouse gas (GHG) traps heat in the atmosphere; all measurements relative to a similar mass of carbon dioxide (CO²), which is indexed at 1.0. The build-up of GHGs can cause climate change.
CFCs – Chlorofluorocarbons (e.g. R-11, R-12) – phased out by the Montreal Protocol in 1996 because of their very high ODPs. Significant impact on both ozone depletion and global warming due to their chlorine and fluorine atoms and very long atmospheric lives.
HCFCs – Hydrochlorofluorocarbons (e.g. R-22, R-123) – also contain chlorine, but contribute less to ozone depletion and climate change due to shorter atmospheric lives. Still in use globally but have phase-out dates scheduled under the Montreal Protocol.
HFCs – Hydrofluorocarbons (e.g. R-134a, R-404A, R-407C, R-410A) – do not contain chlorine, but they do have high GWPs given their fluorine content. Currently targeted for global phase down under the Montreal Protocol.
HFOs and HCFOs – Hydrofluoro-olefins (e.g. R-1234yf, R-1234ze) and Hydrochlorofluoroolefins – next-generation refrigerants that are non-ozone-depleting with ultra-low GWPs and very short atmospheric lives (measured in days vs. years or decades).
HFO BLENDS (e.g. R-452b, R-454b, R-513a, R-514a) – blends including an HFO with lower GWPs.
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