09A - Introduction to Refrigerants Flashcards
What were the three CFC refrigerants originally developed and used in the 90s?
R12, R22, and R502.
What does CFC stand for?
Chlorofluorocarbons
What does HCFC stand for?
Hydrochlorofluorocarbons
What does HFC stand for?
Hydrofluorocarbons
What was the Montreal Protocol? When was it signed?
The Montreal Protocol was a document which went into effect on January 1, 1989. This was designed to ban the production of CFCs in all large, developed countries. This required countries to stop producing CFC refrigerants by January 1, 1996.
What is the EPA?
The Environmental Protection Agency is a US governmental agency charged with enforcing the regulations for working with refrigerants.
What is the Clear Air Act?
The Clean Air Act is a federal law that includes guidelines, restrictions, and penalties for releasing refrigerants into the atmosphere. Fines are assessed up to $37,500 per day, for failure to comply with the Clean Air Act.
What are some of the Clean Air Act violations subject to legal action?
- Venting of CFC, HCFC, HFC, or HFO refrigerants into the atmosphere.
- Failure to recover refrigerant to require evacuation levels before opening equipment for maintenance.
- Falsifying records or failure to keep records.
- Performing refrigeration work without having technician certification according to Section 608 of the Clean Air Act.
- Disposing of refrigeration and air conditioning equipment or cylinders without fully recovering or reclaiming the refrigerant
- Using recovery equipment that is not EPA approved.
What is refrigerant ODP?
Ozone depletion potential is the measurement of the ability of a refrigerant to destroy the ozone layer. The base unit of measurement is the refrigerant R11, which has an ODP of 1.0. The more harmful the refrigerant is to the ozone layer, the higher its ODP.
What is GWP?
Global warming potential is a measure of the ability of a gas to contribute to global warming over time. The baseline gas is carbon dioxide, which has a GWP of 1.0 is commonly measured over a 100 year time period. The higher the GW is, the greater the risk of environmental damage.
What are the refrigerant chemical classifications?
- (CFCs) Chlorofluorocarbons
- (HCFCs) Hydrochlorofluorocarbons
- (HFCs) Hydrofluorocarbons
- (Azeotropic and Zeotropic) Refrigerant Blends
- (HFOs) Hydrofluoro-olefin
- (HCs) Hydrocarbons
What is a CFC?
Chlorofluorocarbons were the first halogen-based refrigerants developed over eighty years ago. CFCs are composed of chlorine, fluorine, and carbon. They are considered to be fully halogenated because all the hydrogen atoms in the original methane or ethane molecule have been replaced by halogens, such as chlorine and fluorine. Two popular CFC refrigerants include R-11, and R-12. They were phased out of production since 1995, but can still be found in some equipment produced before 1995.
How many ozone molecules can be broken apart by one molecule of chlorine?
100,000
What is an HCFC?
Hydrochlorofluorocarbons are refrigerants whose molecules are composed of hydrogen, chlorine, fluorine, and carbon. HCFC molecules include halogens combined with either methane or ethane. Examples of HCFC refrigerants are R-22 and R-123. They have less impact on the ozone layer than fully halogenated CFCs. HCFCs are considered to be partially halogenated because not all the hydrogen atoms have been replaced by chlorine and fluorine. As a result, HCFCs tend to break down in the lower atmosphere and cause less ozone depletion than CFCs. They do however still linger in the atmosphere for a long time and have a high GWP. The EPA requires the complete phaseout of HCFCs by the year 2030.
What is an HFC?
Hydrofluorocarbons are refrigerants that contain hydrogen, fluorine, and carbon. They differ from CFCs and HCFCs in that they contain no chlorine atoms. HCFs have zero ODP. Like HCFCs, HFCs are partially halogenated, but they have a lower ODP than HCFCs because they do not contain chlorine atoms. This makes HFC refrigerants well suited to replace ozone depleting refrigerants. Examples of HFC refrigerants are R-123a, R-152a, and R-404a.
What is a refrigerant blend?
Refrigerant blends are mixtures of two or more established refrigerants. Based on their thermodynamic properties, they are split into the following groups: azeotropes, zeotropes, and near-zeotropes.
What are Azeotropes?
Azeotropes are refrigerant blends that respond to changes in pressure and temperature like a single refrigerant, having fixed boiling and condensing points. An azeotrope maintains constant properties during all operating conditions. At atmospheric pressure, the individual refrigerants will not separate as the blend evaporates or condenses.
Azeotropes can be identified by their ASHRAE classification number series of 500. (Ex: R502, R500)
What are Zeotropes?
Zeotropes are refrigerant blends in which each individual refrigerant that makes up the blend responds differently to conditions based on its individual characteristics. Therefore, a zeotropic blend operates under a range of boiling and condensing points that correspond to the range of its individual refrigerants and the percentage of the blend that each refrigerant makes up.
Zeotropes can be identified by their ASHRAE classification number series of 400. (Ex: R407C, R409A)
What is Fractionation?
Fractionation is the phenomenon where zeotropic blend’s individual refrigerants will separate during phase change. Fractionation can be thought of as the refrigerant splitting up or “fracturing” into its base components. This occurs because the different refrigerants in a zeotropic blend have different boiling points.
What is bubble point?
Bubble point is the temperature at which a liquid zoetrope first begins to boil. The refrigerant with the lowest boiling point boils first.
What is dew point?
Dew point is the temperature at which a vapor zoetrope first begins to condense. The refrigerant with the highest condensing point condenses first.
What is temperature glide?
Temperature glide is the temperature difference between the vapor and liquid state during evaporation or condensing at a constant pressure. Temperature glide is a result of the different boiling and condensing temperatures of a zoetrope’s individual components for a given pressure. This shows as a zoetrope changing its phase and temperature at the same time, and each zeotropic refrigerant blend has its own temperature glide. The common range for temperature glide is 0.3F to 10F.
What is a Near-Azeotrope?
Near-Azeotropes react similarly to zeotropes but respond over a smaller range of boiling and condensing points. Near-azeotropes are technically zeotropes, but allowing them their own category helps to differentiate them more precisely.
What are HFO refrigerants?
Hydrofluoro-olefins are composed of hydrogen, fluorine, and carbon, but they have at least one double bond between the carbon atoms. While HFOs are technically a group of HFCs, they are made from olefins, rather than alkanes. HFOs have zero ODP and very low GWP values. HFOs are miscible in POE lubricants and not soluble in mineral oils or alkylbenzene lubricants. Ex: HFO-1234yf, HFO-1234ze.
What are HCs?
Hydrocarbons are organic substances that contain carbon and hydrogen. These substances are the components in petroleum and natural gas. They are often known for their use as fuel and in the production of plastics, solvents, and industrial chemicals. Hydrocarbons can also be used as refrigerants. Pure hydrocarbons have 0 ODP and a low GWP compared to CFCs, HCFCs, and HFCs. HCs also have better energy efficiency than HFCs.
What is SNAP?
Significant New Alternatives Policy is the EPS’s program that evaluates and regulates substitutes for high ODP refrigerants. It helps to progress the phaseout of older refrigerants and meet the ozone protection provisions of the Clean Air Act. Ex: R-600a (Isobutane), R-290 (propane, R-441A (HC blend)
How are refrigerants identified?
By a standardized numbering system developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE)
