Why are hfo refrigerants less flammable than hydrocarbon refrigerants?
Why are HFO refrigerants less flammable than hydrocarbon refrigerants? They contain Fluorine. Which word applies to the process that returns refrigerant to new product specifications and that requires chemical analysis?
All flammable fluorocarbon refrigerants are classified as an extremely flammable gas. The exception to this is the HFO R-1234ze(E), which GHS classifies as non-flammable (at 20°C). Refrigerant safety classification assesses flammability at higher temperature.
HFO stands for hydrofluoroolefin. The chemical is also made of hydrogen, fluorine, and carbon. However, unlike HFCs, HFOs have zero ODP (Ozone Depletion Potential) and low GWP, making them a more environmentally-friendly option than HFCs. HFOs don't trap heat in our atmosphere and don't contribute to global warming.
R-22a is a hydrocarbon refrigerant blend with primary components including flammable substances such as propane and butane. In some cases, it may also contain small amounts of other hydrocarbons or a pine-scented odorant. This refrigerant is a highly flammable, colorless gas that is heavier than air.
- Energy Efficient. HFO refrigerants reduce emissions over the equipment lifecycle for key applications, like air conditioning and refrigeration. ...
- Lower Cost. Greater efficiency means lower running costs for use in supermarkets, heat pumps, cold transport and much more. ...
- Safe and Reliable.
Why are HFO refrigerants less flammable than hydrocarbon refrigerants? They contain Fluorine. Which word applies to the process that returns refrigerant to new product specifications and that requires chemical analysis?
Highly flammable. Water insoluble. HYDROCARBONS may be incompatible with strong oxidizing agents like nitric acid. Charring of the hydrocarbon may occur followed by ignition of unreacted hydrocarbon and other nearby combustibles.
HFC refrigerants are composed of hydrogen, fluorine and carbon atoms connected by single bonds between the atoms. HFO refrigerants are composed of hydrogen, fluorine and carbon atoms but contain at least one double bond between the carbon atoms.
HFOs “problematic”
Although it has previously been classed as having very low toxicity, recent research has indicated it may impact health. It is extremely persistent in the environment, has high mobility, and cannot be removed by current water treatment technology.
HFOs are highly toxic when dissolved in water and exposed to sunshine. Exposure to Heavy Fuel Oil is toxic to humans and wildlife, and highly polluting to the environment on several dimensions.
Are hydrocarbon refrigerants highly flammable?
The refrigerants that are being introduced to replace HFCs and HCFCs are often hydrocarbons which are flammable. This is leading to the regulation of the importation, exportation and use of those refrigerants.
Is it safe to use hydrocarbon (HC) refrigerants in motor vehicle air conditioners (MVACs)? No. HC refrigerants, such as propane, are highly flammable and are not acceptable alternatives for MVACs under the Clean Air Act and the EPA's Significant New Alternatives Policy (SNAP) Program.
Class 1 refrigerants have low flammability. Class 2L refrigerants are only “mildly” flammable. Class 2 refrigerants are low flammability but higher than 2L. Class 3 refrigerants are highly flammable.
The typical heating value is about 40.9 MJ/kg and the flash point is typically > 60 °C. In order to be suitable for pumping and to achieve sufficient atomization, heavy fuel oil is typically heated up to a level with sufficient margin against the flash point.
In view of the present scenario, it is very important to find new alternatives. HFOs are considered to be the most suitable replacements due to its low global warming potential. Last few decades have witnessed the introduction as well as phasing out of several synthetic refrigerants due to environmental issues.
In general, the process steam efficiencies are: 85%, 90% and 95%.
R22 and R410A are considered to have low flammability levels and are listed as A1. A and B are the toxicity levels of the refrigerant; “A” being lower than “B”, while 1,2 and 3 are the flammability ratings, with 1 being the lowest and 3 being the highest.
The disadvantages of these products are mainly toxicity (NH3), flammability (HC) and high pressures (CO2). However, with minimal skills and compliance with safety rules, they do not eventually prove to be more dangerous than other fluids.
Flammability is the main concern, along with the potential hazards and consequences.
Shorter hydrocarbon molecules have weaker intermolecular forces and lower boiling points. They are highly volatile and therefore extremely flammable.
What happens to the flammability of hydrocarbons?
The flammability decreases with increasing molecular size. As the length of the carbon chain increases, the less flammable the hydrocarbon will be. Longer chain hydrocarbons are more difficult to ignite as compared to shorter chain hydrocarbons.
Hydrocarbon fires are caused by fuels containing carbon being burned in oxygen or air. Most fuels contain significant levels of carbon, including paper, petrol, and methane – as examples of solid, liquid or gaseous fuels – hence hydrocarbon fires.
Refrigerants are divided into two toxicity classes. Class A for low toxicity refrigerants and Class B for for higher toxicity. The two main molecules HFO 1234yf and HFO 1234ze are both Class A, and mixtures containing these molecules will also be Class A.
Refrigerants affected. Among the HFCs and HFC-blend refrigerants affected by the regulations are several that are familiar to facility managers: R-404A, R-134a, and R-410A and R-407C, used to replace R-22. Under the rules, new chillers would no longer be produced using these refrigerants after Jan. 1, 2024.
HC refrigerants have better energy efficiencies and reduced energy usage when compared to currently used HFC refrigerants. These refrigerants are created by nature, not a chemical company, and are often referred to as “natural” refrigerants.
HFO-1336mzz-Z has a normal boiling point of 33.4ºC and a relatively high critical temperature of 171.3 ºC, which result in relatively low vapor pressures and high cycle energy efficiencies.
REFRIGERANTES HFO
HFOs, such as R-1234yf and R-1234ze, are pure solutions used in vehicle air conditioning systems and in chillers respectively, at medium and high temperatures.
It is found that using HFO-1234yf as the air conditioning refrigerant leads to higher exergy efficiency compared to HFC-134a. Also, maximum entropy generation and exergy destruction occur in the compressor.
On a technical level, HFO, which is often referred to as “refinery residual,” is a complex group of hydrocarbon products that consist of the highly viscous and tar-like residues of the crude oil refining process.
One potential alternative to HFO is liquified natural gas (LNG); however, implementation of this fuel requires extensive infrastructural changes.
Does HFO float on water?
The specific gravity of a particular HFO can vary from 0.95 to greater than 1.03. Thus, spilled oil can float, suspend in the water column, or sink. Small changes in water density may dictate whether the oil will sink or float.
As rated by ASHRAE (American Society of Heating, Refrigerating and Air-conditioning Engineers) Standard 34, the safety classification of the most commonly used high pressure refrigerant, R-410A, is A1. As shown in the chart below, A is the lowest toxicity class, and 1 is the lowest flammability class.
For common hydrocarbon fuels, the minimum AIT ranges between 600C (1350 F) for methane (CH4) to 200C (472F) for dodecane (C12H26). A minimum AIT of 190C (450F) is used for the purposes of hazard analysis for aviation kerosene.
Hydrocarbon blends are highly flammable and in a confined space may burn or explode in the presence of an open flame, spark, or cigarette.
Flammability risks of non-toxic refrigerants
A1 designates no flame propagation; A2 indicates lower flammability; and A3 indicates higher flammability. Hydrocarbons such as propane have higher flammability (A3) and are restricted to a lower charge limit that does not address refrigeration needs of large systems.
R-717 has the lowest global warming potential, which is 0 over the course of 100 years. The chemical name for this refrigerant is ammonia, which has molecules with a central nitrogen atom bonded to three hydrogen atoms.
Heavy fuel oil cannot generally be pumped at a temperature of 20°C, and must therefore be preheated in the ship's tanks. To ensure the fuel is or remains pumpable, it must be heated to at least 40°C. At a temperature of 15°C, IFO has a bitumen-like consistency.
LNG cost includes production, liquefaction and logistics and bunkering costs, and therefore, its cost will be different from one area to another. Taking into account the lower heating value (LHV) of fuels, the price of LNG is cheaper than HFO.
HEAVY FUEL OIL (HFO)
All flammable fluorocarbon refrigerants are classified as an extremely flammable gas. The exception to this is the HFO R-1234ze(E), which GHS classifies as non-flammable (at 20°C). Refrigerant safety classification assesses flammability at higher temperature.
What are the main advantages of using hydrocarbons as refrigerants?
The two main advantages of hydrocarbon refrigerants are lower environmental impact and economic gains. First, hydrocarbons do not damage the ozone layer. Moreover, hydrocarbons can significantly reduce emission of greenhouse gases from refrigeration and air conditioning equipment.
Natural hydrocarbon refrigerants provide more efficient cooling due to their high latent heat of evaporation. As a result, smaller compressors can be used leading to greater energy efficiency. With exceptionally low global warming potential natural refrigerants are also better for the environment.
And it was inexpensive: HFO is cheaper than other fuels because it is the leftover or residual product from the oil refining process. Refining removes other fuels such as gasoline and diesel, called distillates, for use in cars, trucks, planes and smaller vessels, leaving the HFO behind.
Vapors may be ignited rapidly when exposed to heat, spark, open flame or other source of ignition. When mixed with air and exposed to an ignition source, flammable vapors can burn in the open or explode in confined spaces. Being heavier than air, vapors may travel long distances to an ignition source and flash back.
HFCs are greenhouse gases because they absorb Earth's outgoing infrared radiation in a spectral range where energy is not removed by CO2 or water vapour.
Hazard Summary
Hydrofluoric acid (HF) and Hydrogen Fluoride (HF) are very poisonous, highly irritating and corrosive. Hydrofluoric acid or Hydrogen Fluoride (HF) is fatal if inhaled, if swallowed, or in contact with skin. It causes severe skin burns and eye damage. The effects may be delayed after exposure.
Crude oil is a flammable, naturally-derived liquid. Its properties vary based on where and when it was extracted. It can also contain measurable amounts of hydrogen sulfide gas, which is toxic.
It is therefore 2 main safety issues that are related to HFOs: flammability and their potential to form dangerous acids.
Exposure to Heavy Fuel Oil is toxic to humans and wildlife, and highly polluting to the environment on several dimensions.
In the MARPOL Marine Convention of 1973, heavy fuel oil is defined either by a density of greater than 900 kg/m³ at 15°C or a kinematic viscosity of more than 180 mm²/s at 50°C. Heavy fuel oils have large percentages of heavy molecules such as long-chain hydrocarbons and aromatics with long-branched side chains.
What is the flash point of HFO?
The flash point is always above 50 °C (122 °F) and the density is always higher than 0.900. In general, heavy fuel oil usually contains cracked residua, reduced crude or cracking coil heavy product which is mixed (cut back) to a specified viscosity with cracked gas oils and fractionator bottoms.
Heavy crude oil has a higher proportion of heavier hydrocarbons composed of longer carbon-plus-hydrogen molecule chains. It is referred to as “heavy” because it has a higher density than light crude oil and actually appears thicker and flows slower.
Peanut oil, safflower oil, and soybean oil all have a smoke point of 450°F. Other smoke points include 445°F for grapeseed oil, 435°F for canola oil, 390°F for sunflower oil, and 410°F for corn oil, olive oil, and sesame seed oil.
Gasoline, paint thinner and turpentine.
One of the most dangerous liquids in the home, gasoline starts approximately 8,000 home fires annually.
Hydrofluro-Olefins (HFO) are considered the 4th generation of fluorinated refrigerant gases (GF). With a zero ozone depletion potential (ODP) and a low global warming potential (GWP), they are the fluorinated gas solutions with the lowest environmental impact.
One potential alternative to HFO is liquified natural gas (LNG); however, implementation of this fuel requires extensive infrastructural changes.
HFO refrigerants are composed of hydrogen, fluorine and carbon atoms but contain at least one double bond between the carbon atoms. The first HFO, jointly developed by DuPont and Honeywell, is HFO 1234yf which is sold under the brand names Opteon YF and SOLSTICE yf.
A prohibition on the use and carriage of heavy fuel oil as fuels in Arctic waters will come into effect in 2024, as part of amendments to MARPOL Annex I, MEPC.
