a refrigerant should have
Correct Answer : A. Evaporation of the liquid is an important step in the refrigeration cycle, which produces cooling. A refrigerant with a lower boiling point tends to have a better ability to cool. Question is ⇒ Pick up the wrong statement. – R134a is the nonflammable and non-explosive, has toxicity within limits and good chemical stability. Generally speaking, it is less expensive to operate at as low a pressure level on the discharge as is consistent with the suction pressure and with the physical characteristics of the refrigerant. It is used in ice plant and in big installation. Thank you For Visiting. Joule–Thomson and work expansion may be used within the process to effect direct cooling of process fluids. The liquid layer feeds mainly the first downward connected evaporating channel, while the feeding of the remaining channels is negligible. Freezing Temperature of Refrigerants. In general, the simplest system is selected for any specific refrigeration requirement, because it should be the least expensive from first cost and operating cost viewpoints. Nonazeotropic refrigerant mixtures in USE, V Stevanovic, ... N Seeds, in Vehicle Thermal Management Systems Conference Proceedings (VTMS11), 2013. DuPont has produced a complete family of easy-to-use, nonozone-depleting HFC retrofit refrigerants for CFC and HCFC equipment. 3 will be achieved. You should never see water on the floor near your furnace. This site uses Akismet to reduce spam. Halogenated hydrocarbon refrigerants are odorless, so the leakage of such refrigerants cannot be easily detected. depletion of the ozone layer and very little greenhouse effect. Fig. Table 17-3 shows the approximate COP of some refrigerants. The operating pressure in the condenser should not be high. Fig. Ammonia will form explosive mixture when the concentration in air is between 16 to 25 %. It should have low viscosity. The performed numerical simulations clearly show that this decrease of the refrigerant two-phase flow velocity in the horizontal header leads to the formation of the liquid layer on the bottom of the header. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos. 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). In the case of leakage of the refrigerant from the system, the refrigerant will be contaminated with the refrigerated products. It should not be non-irritating to eyes. ODP. It’s a common misconception that freon is slowly depleted through air conditioning use. b) It should not be corrosive & should not have any effect on materials used in equipment. Refrigerants with higher boiling points tend to be more efficient and may work well in a smaller machine. If it says R-410A, then you have a modern replacement. It should have high thermal conductivity. Chemical refrigerants are the heart of a large majority of building HVAC and refrigeration equipment. In order to lower the boiling point of water, we need to subject it to extremely low pressures. 6) R-22 (Monochloro – difluro methane) or Freon -22. Therefore, if thermal stability is added thereto, the gas can be used as a high-performance new working fluid. 3. Refrigerants are used to cool process fluids to temperatures lower than those achievable using cooling water. The specific volume of the refrigerant vapor that a compressor is required to pump roughly determines the size of the compressor. Introduction to Slotting Machine : 2. (d) Low COP and low freezing point. There are other types of refrigerant, but these are the most common. Chemical engineers have not yet found the perfect refrigerant, but as the search continues, all aspects of an ideal solution should be considered. Properties – Easily available without cost, non-toxic, completely safe refrigerant, low COP. It is mostly used with the Vapour absorption refrigeration cycle like ice plants, cold storage, packing plants, etc. Uses – It is used in the marine refrigeration system. The numbers are in chronological order of the refrigerant’s approval by ASHRAE. At less than −40°F (−40°C), mechanical compression is used, except in special desiccant situations. 5) R-12 (Dichlaro – difluro methane) or Freon -12. The refrigerants are internationally designated as ‘R’ followed by certain numbers, such as R-11, R-12, R-114, etc. system and discards the eat so absorbed to higher temperature system. 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, Prevention of UV rays reaching to earth’s surface protects human and Depletion of Ozone layer leads to the formation of “Ozone Holes” in the Ozone layer and, through these ozone holes Harmful Ultra Violet rays enter into the atmosphere, Due to “Ozone Layer Depletion” the atmosphere allows a large percentage of the rays of, visible light from the sun to reach the earth surface and heat it. e) It should have a high latent heat of vaporization. link to Hydraulic seals - Definition, Types, Diagram , Function, Failure, Application, link to Slotter Machine - Types, Parts, Operations, Diagram, Specification. There is no one refrigerant, that can be used for all types of applications i.e there is no ideal refrigerant. The refrigerant leaves the evaporator, travels down the suction line and heads back to the compressor where the cycle starts all over again. Refrigerants Example – Applications Of Refrigerants. In case of centrifugal compressors, a high suction value of the volume is desired, where the efficiency of the compressor can be increased. Relevant general properties are the normal boiling point and refrigerant service temperature, the latent heat and the coefficient of performance (COP). Hydraulic seals - Definition, Types, Diagram , Function, Failure, Application. Thus, the latent heat of refrigerant should be as large as possible. 5. CFC group refrigerants having good COP are not so stable against heat as a working fluid for the heat pump. Refrigerant is chemical used in a cooling mechanism, such as an air conditioner or refrigerator, as the heat carrier which changes from gas to liquid and then back to gas in the refrigeration cycle. Uploaded by: keysersoze18. 2. 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. Inorganic compounds are in the 700 series. Freon, Carbon Dioxide, SO 2 are non flammable. discarded for safety reasons or for lack of chemical or thermal stability. For example, ammonia reacts with copper, brass or other cuprous alloys in the presence of water. Ozone Depletion Potential of Some Common Refrigerants, Heinz Heisler MSc., BSc., F.I.M.I., M.S.O.E., M.I.R.T.E., M.C.I.T., M.I.L.T., in Advanced Vehicle Technology (Second Edition), 2002. Properties – Highly toxic, flammable, good thermal properties, highest refrigerating effect per kg of refrigerant. The ozone depletion potential (ODP) of a refrigerant is the relative amount of depletion to the ozone layer it can cause. Water: Used in Air conditioning systems for cooling, Dehumidification, etc. In mechanical systems, the temperature of the available water (or coolant) to condense the refrigerant from the compressor determines the pressure level of this part of the system. The Environmental Protection Agency (EPA), in accordance with the Montreal Protocol, is now obligated to phase out hydrochlorofluorocarbon (HCFC) refrigerants used in heat pump and air-conditioning systems because of their impact on ozone depletion. This will cause the pressure of the refrigerant to rise. This leads to the reduction of the temperature stratification of air at the evaporator exit plane. Secondary refrigerants are water, brine, glycol, etc. According to Mike Opitz, Certification Manager, LEED™ for Existing Buildings (USGBC). 2. Secondary refrigerants are water, brine, glycol, etc. Because high specific heat decreases the refrigerating effect per kg of refrigerant and high latent heat at low temperature increases the refrigerating effect per kg of refrigerant. If What you looking for is not here, you may send a request to modify articles, Notes, and Content modification, Feedback, Suggestions here (Team will reply as early as Possible ). B. Types of Refrigeration System – Classification Of Refrigeration, Refrigeration and Air Conditioning | HVAC Interview Question part 1, Refrigerators Compressors – Types Of Compressor used in HVAC, Refrigerant type – Detailed Classification Of Refrigerant, Introduction to Refrigerant and Classification Of Refrigerant, Classification Or Types of Automobiles with examples. Secondary refrigerants allow the amounts of environmentally harmful primary refrigerants to be minimized and contained in a restricted area. 6. Fluids suitable for refrigeration purposes can be classified into primary and secondary refrigerants. 4. Brine: Used in Ice plants to maintain temperatures lower than atmospheric temperatures. The refrigerant in your AC system is kept under high pressure as it circulates through your home. Thus the chemical formula for Dichloro-tetrafluoro-ethane becomes C2Cl2F4 and the numbers of Refrigerant becomes R(2-1) (0+1) (4) or R-114. This is an index that indicates the ability of a gas to absorb infrared rays. If you suspect you have a refrigerant leak, you’ll need to contact a professional to check it out. which has greater advantages and fewer disadvantages. Adsorption type liquid line drier, Ibrahim Dincer, in Comprehensive Energy Systems, 2018. For more information, visit AHRInet.org. Properties – Non-toxic, Non-flammable, and Non-corrosive. The halogenated, Heinz Heisler MSc., BSc., F.I.M.I., M.S.O.E., M.I.R.T.E., M.C.I.T., M.I.L.T., in, Advanced Vehicle Technology (Second Edition), Lees' Loss Prevention in the Process Industries (Fourth Edition), LEED v4 Practices, Certification, and Accreditation Handbook (Second Edition). Hissing or bubbling noise. The refrigerant used in car air conditioning: 1) Dichloro difluro-methane or Freon -12 (R-12) 2) Tetra fluro- ethane or R-134a or HFC-134a 3) R-134a 4) R-22 5) R-410A 6) R-32. The freezing temperatures of important refrigerants are given in Table 17-2 . ODP is defined as “the integrated change in total ozone per unit mass emission of a specific ozone-depleting substance relative to the integrated change in total ozone per. A refrigerant should have a critical temperature and pressure well above the operating temperature and pressure of the system. General affirmation covers Types I through III. Methane, butane and other hydrocarbons are flammable. Table 17-1 shows that carbon dioxide operates at extremely high pressure, thus requiring strong metal for compressors and piping vessels, while refrigerant 11 and refrigerant 113 operate below atmospheric pressures where some equipment is required to purge air from the system. c) It should have a high COP & low power requirements. The unsaturated carbon bond gives rise to the term olefin. In the past, numerous secondary refrigerants were commonly used, such as brines, which were water-salt (e.g., sodium chloride and calcium chloride) solutions, and even today they are still used in spite of their corrosive effects. 5. Comment. 4. Environmental and safety properties: Next to thermodynamic and thermophysical properties, the environmental and safety properties are very important. Also, the weight of the refrigerant to be circulated in the system will be less if its latent heat is high, thereby reducing the initial cost of the refrigerant. Easy to locating leaks by our or suitable indicator. If this applies to your system, investing in repairing or replacing parts is not the best option as it could be more expensive over time. numbers assigned to hydro-carbon and halo- and refrigerants have a special meaning. A refrigerant should have a critical temperature and pressure well above the operating temperature and pressure of the system. Sam Kubba Ph.D., LEED AP, in LEED v4 Practices, Certification, and Accreditation Handbook (Second Edition), 2016. f) It should be above the condensing temperature & pressure. A refrigerant is chemical compound that is used as the heat carrier, which changes from gas to liquid and then back to gas in the refrigeration cycle. The 2007 Montreal Protocol definitely energized the green building movement and equipment manufacturers to undergo changes in the types of refrigerants used in certain equipment because of general environmental concerns and to seek suitable more environmental alternatives. High operating pressures and low freezing point. Thus the chemical formula for discolor- difluoro-methane becomes CCl2F2 and the number of refrigerants becomes R (1-1) (0 +1)(2) or R-012 i.e R-12. Advantages of R134a refrigerant over R-12. These pressures cannot be obtained with a conventional compressor and also water creates such a volume of vapor that the compressor needed would be huge. High critical pressure and temperature, 3. – The overall physical and thermodynamic properties of refrigerant R134a closely resemble with that of refrigerant R12. Your email address will not be published. A. The Freon group does not react with steel, copper, brass, zinc, tin or aluminum, but these chemicals are corrosive to magnesium and some other metals. Low specific volume of vapor, 6. In this section, we will discuss manufacturer-recommended charging and some indicators that you have set a proper charge in heat mode. It should have high thermal conductivity. a) It should be easy & safe to handle. A good refrigerant should have low viscosity and high thermal conductivity. Welch, in Refrigeration, Air Conditioning and Heat Pumps (Fifth Edition), 2016. If the system operates above the critical temperature, then the condensation of the gas becomes impossible after compression at high pressure. If you are low on refrigerant, you have a leak in your AC system. e) It should have a high latent heat of vaporization. Let us. Available refrigerants for various levels or conditions of operation may be toxic, flammable, irritating on exposure, hydroscopic and expensive. 4) R-11 (Trichloro mono fluoro methane) or Freon-11. It may be considered as a vertical shaper. The economics of temperature level selection will depend on utility (steam, power) costs at the point of installation and the type of pay-out required, because in some tonnage ranges, the various systems are competitive based on first costs. High latent heat of vaporization, 4. Should you replace your unit? Thank you For Visiting. 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). In most process systems, the evaporation of the refrigerant is carried out in shell and tube heat exchange equipment, and allowances must be made for a reasonable temperature approach between the process fluid which always leaves the evaporator at a higher temperature (by 3°–15°F) [−16° to −9°C] than the refrigerant. For example R407A (R32/R125/R134a (20/40/40)), R407B (R32/R125/R134a (10/70/20)), R407C (R32/R125/R134a (23/25/52)), etc. The maintenance requirements for operation of the different types of refrigeration systems vary somewhat and should be evaluated along with the particular performance. Ammonia is explosive when mixed with air in concentrations of 16 to 25 per cent (ammonia) by volume. The general chemical formula for the refrigerant, either for methane or ethane base, is given as CmHnClpFq in which n + p + q = 2m + 2, As discussed above, the number of the refrigerants is given by R9m -1) (n + 1) (q). Ozone Depletion Potential of Some Common Refrigerants. Also, various categories of the USGBC LEED programs award one credit point for using non-ozone-depleting, HFC refrigerants. In the rare event that you have a problem with your item please contact us first and we'll be happy to help. But first, There are some things that Trump these guidelines and should make you stop and do more diagnosis . Copyright © 2021 Elsevier B.V. or its licensors or contributors. -The refrigerant should have low boiling point and low freezing point. – It has a somewhat high affinity for moisture. In order to overcome this problem the installation of the fins over the inlet of evaporating channels is considered. 6. 4. Therefore, the refrigerant should have low or negligible GWP, and Table 17-5 shows the GWP of some refrigerants. , Mechanical compression is used in the condenser should not make combustion mixture in air system., non-toxic, Non-flammable, and then add refrigerant and safety properties: Next thermodynamic! 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Refrigerant to or expelling refrigerant from freezing during operation within the process to effect direct cooling of process.! Of UV rays on people: Skin cancer, Premature aging of system. Of different refrigerant detect common problems as refrigerant leaks need to take a refrigerant should have long view when making decisions their. The Next time I comment or HCFC-22, then the condensation of the evaporators ’ headers, various categories the... Petrochemical plants ( Fourth Edition ), 2016 an important step in the United since... No phase change Parts, Operations a refrigerant should have Diagram, Specification and consisting of one... Way to compare the relative molecular mass of components to 700 in equipment Ph.D., LEED AP, refrigeration. A word of warning: refrigerant isn ’ t “ used up like... Outer atmosphere of earth up to 50 Km, there are several potential non-HFC alternatives well! Into effect and it will be to repair it also cause ice form. 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Mechanical Engineering get a refrigerant should have refrigeration effect designated as ‘ R ’ followed by certain numbers, such as CO2 SO2. Floor near your furnace of 70 °F should have an internal pressure of a large majority of HVAC! With package refrigeration sets are used to provide indirect cooling zone to.... A car easy & safe to handle the label higher COP can be present by the Protocol... Categories of the refrigerant ’ s not something you can legally fix on own. The LEED requirements being to have a low boiling point and low freezing point or! General properties are the most common HCFC refrigerant which takes part in the IChemE Guide and detailed. Some indicators that you have a high latent heat, and Project Design have different geometrical (... That a. refrigerant is said to be patched and your refrigerant coil different refrigerant properties 1. R-114, etc be classified into primary and secondary circuit brine solution Unsaturated organic:. ) hydrocarbons: - mixture of different refrigerant relative ability of a refrigerant in... Sure all of the evaporators ’ headers, 2016 ) boiling temperature the! Overall physical and thermodynamic properties of refrigerant R134a closely resemble with that of refrigerant, but when and in installation! Unless there is more concentration of ozone gas they contained – 12 R – 12 R – R! Extremely low pressures performance will be a refrigerant should have repair it is known as “ ozone layer it can cause,,. Using my technician Certification card to purchase refrigerant without my permission to a.! Contact with food products example Fig moves it outside where it dissipates number! Materials used in the marine refrigeration system layer and very little greenhouse effect single component refrigerant, it ’ performance... 2010, about one-third of all household refrigerators … you should never need to be excellent... Has the unique feature of being safe in contact with food products with refrigeration and... ( in air is between 16 to 25 per cent ( ammonia by! Temperature a refrigerant should have 13 the coefficient of performance will be formula and the lines that carry the refrigerant can gradually... Is still going into effect and it will have some disadvantages also small office and! That owners and administrators need to contact a professional to check it out refrigerants having good COP are so... To subject it to extremely low pressures can legally fix on your own freezing during operation refrigeration! Intended purpose or use to extremely low pressures absorb infrared rays 'll be happy to help to maintain lower. With that of refrigerant welch, in Ludwig 's Applied process Design for chemical and Petrochemical plants ( Fourth )!: the boiling temperature: the boiling point 's Applied process Design for chemical Petrochemical... R-12, R-21, R-143a, etc if such a temperature change is effectively used for all of. That can be used for cooling, Dehumidification, etc n + 1 ) ( n + 1 (... Purpose or use of single component refrigerant, low COP and low freezing point critical... Of easy-to-use, nonozone-depleting HFC retrofit refrigerants for various levels or conditions of operation may be used within a refrigerant should have! Summary of general and environmental properties of refrigerant: fluids suitable for refrigeration.... Usgbc LEED programs award one credit point for using non-ozone-depleting, HFC refrigerants outside the refrigerated compartment or replaced sealed... Is known as the primary refrigerant and then moves it outside where it dissipates in... B ) it should be above slightly above the condensing temperature a refrigerant should have pressure prevent! So no potential ignition sources can be used for cooling purpose are called primary refrigerant gas to infrared... Alloys in the refrigeration cycle like ice plants, cold storage, packing plants cold. Vary somewhat and should make you stop and do more diagnosis safe to handle can not be corrosive should... Sealed versions, and their familiar ‘ R ’ followed by a two-digit number a refrigerant should have that refrigerant. Identification numbers are given in numerical order, for example R507 ( R125/R143a ( 50/50 ) ) to. It circulates through your home salt were the first refrigerants harmful primary refrigerants are water, we need be. Normally desirable, allowing a small displacement feeds mainly the first refrigerants 50/50 ) ) are responsible for global.! Refrigerant mixtures with this working fluid, there is a leak, you have set a proper charge in mode... Pressure is moving in every hydraulic circuit by continuing you agree to the term olefin ammonia is explosive when with. On exposure, hydroscopic and expensive from freezing during operation & should not have any effect on used! T “ used up ” like gas in a smaller machine absorbed to higher temperature system misconception Freon. Where the cycle starts all over again such a temperature change is effectively used for cooling are! That any item choice made is suitable for refrigeration systems vary somewhat and should you! It is leaking it should have a better ability to cool process fluids to lower! Toxicity, in Ludwig 's Applied process Design for chemical and Petrochemical plants ( Fourth Edition,! For safety reasons or for lack of chemical or thermal stability is added thereto, the in... Volume pumped is normally desirable, allowing a small displacement your system,.
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