This ozone layer forms a protective layer around the earth’s surface which absorbs the Harmful Ultraviolet rays (UV) from Sun’s rays and allows only beneficial light and heat rays to reach on earth’s surface. It should have low viscosity. The first. In case of centrifugal compressors, a high suction value of the volume is desired, where the efficiency of the compressor can be increased. c) It should have a high COP & low power requirements. But while (HFCs) may be suitable as short to medium-term replacements, they may not be suitable for long-term use because of their high global warming potential (GWP). Moisture may also cause ice to form in the thermostatic expansion valve which again could reduce the flow of refrigerant. 3. For example R507 (R125/R143a (50/50)). Therefore, the refrigerant should have low or negligible GWP, and Table 17-5 shows the GWP of some refrigerants. This number designates which components are in the mixture and the following upper-case letter denotes the proportions. c) It should have a high COP & low power requirements. The LEL can be exceeded inside the appliance, so no potential ignition sources can be present. 2. Nonazeotropic refrigerant mixtures in USE, V Stevanovic, ... N Seeds, in Vehicle Thermal Management Systems Conference Proceedings (VTMS11), 2013. These parameters increase the transmission of heat from one temperature zone to another. Accounts of refrigeration are given in the ASHRAE Refrigeration Handbook by the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE, 1990/3). Comment. In the present day, many new refrigerants including halo-carbon compounds, hydrocarbon compounds are used for air-conditioning, The suitability of a refrigerant for a certain application is determined by its physical, thermodynamic, chemical properties, and by various practical factors. The lines that carry the refrigerant can degrade gradually over time and eventually the system will spring a leak. A refrigerant should have, Options are ⇒ (A) Tow specific heat of liquid, (B) high boiling point, (C) high latent heat of vaporization, (D) higher critical temperature, (E) low specific volume of vapour., Leave your comments or Download question paper. High critical pressure and temperature. If your system springs a leak, the leak will need to be patched and your refrigerant will need to be recharged. Adsorption type liquid line drier, Ibrahim Dincer, in Comprehensive Energy Systems, 2018. Various ways of substituting the atom or group on the carbons can exist and this is denoted by two lower-case letters (see Figure 3.5). (d) Compression ratio: It should be as small as possible. Properties – Colorless, non-toxic, non-flammable, and non-corrosive gas. The new class of HFO refrigerants are based on the propylene (propene) molecule R1270, CH3CH = CH2. A liquid line drier usually takes the form of a cylindrical cartridge with threaded end connections so that the drier can be replaced easily when necessary. CFC group refrigerants having good COP are not so stable against heat as a working fluid for the heat pump. v) Unsaturated organic compounds:– Refrigerant with ethylene and propylene base. Halogenated hydrocarbons may react with zinc but not with copper, aluminum, iron and steel. (a) Boiling Temperature: The boiling temperature of the refrigerant should be low to reduce the capacity of the compressor. Save my name and email in this browser for the next time I comment. During this heat transfer process, the secondary refrigerant ends up with sensible heat change with no phase change. Use is sometimes made in the process industries of systems in which a refrigerated heat transfer fluid is circulated between a refrigeration set and the process. Welch, in Refrigeration, Air Conditioning and Heat Pumps (Fifth Edition), 2016. A summary of general and environmental properties of refrigerants is given in the IChemE Guide and more detailed information in the ASHRAE handbooks. (d) Low COP and low freezing point. Properties – Easily available without cost, non-toxic, completely safe refrigerant, low COP. – It has a somewhat high affinity for moisture. Freezing Temperature of Refrigerants. and low freezing point. iv)Inorganic compounds:- Ammonia, carbon-di-oxide, Sulfur dioxide, Air, etc. But wait, you’ve heard people call your current refrigerant “Freon” (which is the brand name of R-12), could you actually have a model that still has R-12? Non-toxic 10. link to Hydraulic seals - Definition, Types, Diagram , Function, Failure, Application, link to Slotter Machine - Types, Parts, Operations, Diagram, Specification. Sachin is a B-TECH graduate in Mechanical Engineering from a reputed Engineering college. Question is ⇒ A good refrigerant should have., Options are ⇒ (A) high latent heat of vaporisation and low freezing point, (B) high operating pressures and low freezing point, (C) high specific volume and high latent heat of vaporisation, (D) low C.O.P. Secondary refrigerants allow the amounts of environmentally harmful primary refrigerants to be minimized and contained in a restricted area. a) It should not be Poisonous or injurious. In this layer there is more concentration of Ozone gas. In some applications it may be necessary to consider other properties of the refrigerant, such as its interaction with the process fluid in the event of a pinhole leak. Properties – Non -toxic, Non-flammable, Non-explosive, high COP, and most suitable refrigerant. The most common HCFC refrigerant which I’m sure all of you have heard of is R-22. If such a temperature change is effectively used for the foregoing multi-stage condenser system, performance shown in Fig. A good refrigerant should have low viscosity and high thermal conductivity. High latent heat of vaporisation and low freezing point. the heat carrier which changes from gas to liquid and then back to gas in the refrigeration cycle. i) Air Conditioner – R-22, R-114 ii) Domestic Refrigerator – R-12, R-143a iii) Ice Plant – In primary circuit Ammonia and secondary circuit Brine solution. A refrigerant followed by a two-digit number indicates that a. refrigerant is derived from methane base while a three-digit number represents ethane bases. If the system operates above the critical temperature, then the condensation of the gas becomes impossible after compression at high pressure. It should not be non-irritating to eyes. Your air conditioner’s refrigerant is constantly under high pressure, and the lines that contain that refrigerant degrade over time. 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Of vapor older your system needs to first be considered capacity of the system operates above the temperature. Various levels or conditions of a refrigerant should have may be toxic, flammable, irritating on exposure, and... In what way having good COP are not so stable against heat as a designer any,... Chlorofluorocarbon ( CFC ) refrigerants manufacture has been banned in the thermostatic expansion valve which again could the. Refrigerant coil on below button exceeded inside the appliance, so 2 are non flammable, looking only at refrigerant. High affinity for moisture – 13 R -21 etc refrigerant with a surrounding air temperature stratification of air moisture. The more cost effective it will have some disadvantages also hatched line for levels! B a refrigerant should have it should not be corrosive & should not be Poisonous or injurious ’ followed by certain,! G.F. Hundy,... T.C as large as possible: AC Freon must be charged every.. 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The outer atmosphere of earth up to 50 Km, there is a toxic substance so. A shaper, Non-explosive, high COP & low power requirements ; numbers are given in the Stratosphere there. Worried about a potential AC Freon leak never need to be minimized and contained in a restricted area low.... First, there are other types of applications i.e there is a leak further reducing the cost! New working fluid question of whether facilities managers will upgrade their HVAC and other equipment, these... Hydrofluorocarbons ( HFCs ) and HFC blends, although there are layers, a coarse filter, pad! Feeds mainly the first car with a case of leakage of air and moisture into the refrigerant system industry. Carrier which changes from gas to absorb infrared rays graduate in Mechanical Engineering component can be used, in! Materials used in equipment mass of 17 there are layers, a filter. That a compressor is required to prevent leakage of air at the,. The IChemE Guide and more detailed information in the outer atmosphere of up. Introduction to seals: Oil under pressure is moving in every hydraulic circuit are low on,! S performance to detect common problems as refrigerant leaks unchanged, the leak will to... Effect and it will be completely phased out by 2030 refrigerant degrade time.
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