Possible replacements for these refrigerants in commercial applications include ashrae class 2l refrigerants, which have lower global warming potentials but are mildly flammable. Chlorofluorocarbons cfcs, hydrochlorofluorocarbons hcfcs and hydrofluorocarbons hfcs are synthetic substances used as refrigerants. Table of contents 2018 ashrae handbookrefrigeration. Refrigerants are widely used in refrigeration cycle where cooling effect below the atmospheric temperatures are needed. Following the discovery that some of these chemical compounds may be harmful to the environment, they are being replaced with more environmentally friendly alternatives see figure 5. Pdf refrigerant types, issues, trends and future options.
The refrigerants should preferably be nonflammable and nonexplosive. Desirable properties of refrigerants used in refrigeration. Risk assessment of refrigeration systems using a2l. A refrigerant is a substance or mixture, usually a fluid, used in a heat pump and refrigeration. Toxicity classification of refrigerants is assigned to classes a or b. Some comments on the refrigerants presented in the table are given below. Class a signifies refrigerants for which toxicity has not been identified. R4a is also known as tetrafluoroethane cf3ch2f from the family of hfc refrigerant. The usage of oil free compressors solves many of the problems that lubricants consisting of a mixture of oil and refrigerant cause. The ideal working fluid or often called refrigerant would have favorable thermodynamic properties, be noncorrosive to mechanical components, and be safe, including freedom from toxicity and flammability. Jul 04, 2017 refrigerant nomenclature nomenclature of refrigerants refrigeration and air conditioning. Here are some of the desirable properties of refrigerant explained in detail.
Desirable refrigerants are those which possess chemical, physical, and thermodynamic properties that permit their efficient application and service, in practical designs of refrigerating equipment. There must be large difference in the boiling points of refrigerant and absorbent greater than 2000 0c, so. Refrigerants properties pdf product data summary and thermodynamic tables. In refrigeration and air conditioning applications there are wide range of conditions in which the refrigerants. The properties examined in this study were toxicity, flammability, explosion potential, global warming potential, ozone depletion potential and efficiency.
Compressor has to be operated at high vacuum if the boiling point of the refrigerant is high at atmospheric pressure. Primary refrigerants change states to absorb heat from surrounding areas or substances. Pdf influence of refrigerant r4ar1234yf properties. This article presents a comparison of the properties and performance of hydrocarbons as refrigerants in smallsize heat pump and refrigeration systems of several. In addition, a chapter is devoted to the issue of refrigerant selection, and a further chapter focuses on refrigerating devices that do not operate the vapour compression cycle. It is the fluid that flows continuously through the refrigeration cycle or vapor compression cycle absorbing heat from the low temperature reservoir and throwing it to the atmosphere or any other high temperature reservoir.
This article describes thermodynamic properties of the refrigerants the ideal refrigerant. The refrigerants have a thermodynamic property chart on pressureenthalpy coordinates with an abbreviated set of tabular data for saturated liquid and vapor on the faci ng page. Refrigerants are substances that can be used in the refrigeration cycle of air conditioning and refrigeration equipment because of their thermodynamic properties. Mle is a method for estimating parameters of a statistical model. This article has been excerpted from a comprehensive white paper, refrigerants for commercial refrigeration applications, issued by copeland corp. The liquid at the evaporator coil should therefore vapourise easily, otherwise the compressor will have to create too much of vacuum to cause the liquid to vapourise. The refrigerant in any refrigerator or air conditioner flows continuously through the vapor compression cycle, absorbing the heat in the evaporator and releasing it in the. Originally the title given was new and alternative refrigerants but i was also asked to. Synthetic and organic refrigerants are classified under two main categories, primary and secondary. Safety properties of refrigerants considering flammability and toxicity are defined by.
R32 is a chlorinefree, ozonesafe fluorocarbon whose boiling point is 52c. Ecofriendly refrigerants h c f c r 2 2, r 1 2 4 h f c r 1 3 4 a, r 1 5 2 a n a t u r a l r e f r i g e r a n t n h 3, h c s c f c a l t e r n a t i v e s. The free water apart from the dissolved water in refrigerant freezes below 0 deg c. New, natural and alternative refrigerants by dr s f pearson of star refrigeration limited introduction it is an honour to be invited to present this paper despite the rather daunting title. Positively innovative refrigerants r32 daikin chemical europe. With the discovery of the damaging effect of cfcs and hcfcs refrigerants to the ozone layer, the hfc family of refrigerant has been widely used as their replacement. New refrigerants to replace cfcs comprise an active area of development. In fact, from the thermodynamic or heatcarrying standpoint, differences among refrigerants with similar boiling points are small. However, important practical issues such as the system design, size, initial and operating costs, safety, reliability, and serviceability etc. Detailed comparison is made on first generation, second generation and third generation refrigerants, including the option of using hcs and co 2. Which of the following is not a desirable property for new refrigerants high boiling point which of the following refrigerants has a low gwp and can be used as a replacement for r4a in automotive air conditioning. A blank numerically shows the thermodynamic properties of a refrigerant under saturated conditions. The purpose of this standard is to establish purity specifications, to verify composition, and to specify the associated methods of testing for acceptability of the refrigerants listed in section 2. Refrigerants should have low freezing point than the normal operating conditions.
The liquid has to vapourise at the evaporator coil to cause cooling. The article focuses on the criteria for refrigerant selection, including discussion of the transitional refrigerants hcfcs, chlorine free refrigerants hfcs, and halogen free refrigerants. R22 chc1f425 and r11 cc1435f are colorless, nonexplosive, nonpoisonous refrigerants with many properties similar to those of r12. Fellow ashrae mcquay international staunton, virginia usa 1 what is a refrigerant. Many different refrigerants have been used in the past and are in use today with good ability to transfer heat from one place to another. Lets look at the properties of these and other refrigerants. These two refrigerant thermodynamic properties are similar to each other, making it a desirable choice for future automotive refrigerants. The process is not easy, and although there are alternatives to old refrigerants, the new ones are usually not. For flammable refrigerants special precautions should be taken to avoid accidents. Mixtures of r12 vapor and air, in all proportions, will not irritate your eyes, nose, throat, or lungs. Working fluids in refrigeration cycles undergoes phase transition in cycles mostly before going to subject topic first of all we divide all refrigerants in following categories. In fact, from the thermodynamic or heatcarrying standpoint, differences among refrigerants with similar. In addition, if the volume of charge is large, there should be no danger to health and property in case of its escape. Usually, a fluid, used in a heat pump and refrigeration cycle that can extract heat from another body or substance.
The september 2017 addendum 1 has been incorporated into the already published 2017 version of. Low viscosity of the refrigerant in both states are desirable. The weight of the refrigerant required to be circulated in the system per unit of refrigerating effect will be low if the latent heat of refrigerant is high. It would not cause ozone depletion or climate change. Any substance which has appropriate thermal properties can be used as a refrigerant, but in practice the choice is limited by many factors such as toxicity, flammability, chemical stability, and the behaviors of the refrigerant with lubricating oil, water and construction materials. In todays world, other properties of the refrigerant are more important. The refrigerant is the fluid that is used in the vapor compression refrigeration system for carrying the heat from the substance or the fluid to be cooled and throws it to the atmosphere. Physical properties of refrigerants low freezing point. Nist standard reference database 23, refprop thermo dynamic properties of refrigerants and refrigerant mixtures, version 3. Refrigerants with higher boiling points tend to be more efficient and may work well in a smaller machine.
The production and use of cfcs is restricted by the montreal protocols. Learn the types of refrigerants bright hub engineering. R32 has a gwp about one third that of r410a, and it has excellent properties. These refrigerants will evaporate at cold temperatures and so the heat absorbed is in the form of latent energy.
The institute of refrigeration refrigerants americas. Apr 12, 2020 refrigerants are widely used in refrigeration cycle where cooling effect below the atmospheric temperatures are needed. Ashrae position document on refrigerants and their. Desirable properties of refrigerants chemical engineering site. Secondary refrigerants allow the amounts of environmentally harmful primary refrigerants to be minimized and contained in a restricted area. This section presents data for the thermodynamic and transport properties of refrigerants, arranged for the occasional users. Duponttm refrigerants, technical information keywords. The general conclusion of the thesis is that the refrigerant affects all of the measured properties negatively on the subject of lubrication and life of the rolling element bearing. What is a refrigerant and desired properties of a refrigerant scribd. Hence, the study for the performance characteristics for refrigerants has become necessary in order to evaluate an ecofriendly refrigerant which is bound to protect the environment from dreadful substances.
Thermodynamic properties of duponttm freonr 22 refrigerant. It has the highest refrigeration effect per kilogram of all refrigerants and comes at a low cost. High conductivity of refrigerant in both states are desirable. It has long been used in a variety of airconditioning and refrigeration applications in a variety of. Some important physicalchemical properties of refrigerants.
Safety properties of refrigerants considering flammability and toxicity are defined by ashrae standard 34 1. The refrigerants have a thermodynamic property charge. Refrigerant is the life blood of the vapor compression cycle. Whenever we choose them for particular use properties of refrigerants also plays a vital role in economic and environmental friendly application. This also reduces the initial cost of the refrigerant used in the system. High latent heat of refrigerant at evaporator temperature is desirable. Toxic pressures to the previous refrigerant with zero odp from dupont halogen free refrigerants 09. Since different fluids have the desired traits in different degree, choice is a matter of. Properties of refrigerants n low boiling point and high latent heat of vaporization n dense vapor n low toxicity n non flammable n low miscibility with oil. Halocarbon refrigerants halocarbon refrigerant are all.
The desired thermodynamic properties are a boiling point somewhat below the target temperature, a high heat of vaporization. R32 and r125 are seldom used as single refrigerants, but only in mixtures with particularly favorable thermodynamic properties. Because of the similarities between r22, r11, and r12, only r12 is discussed. May 01, 2014 following are the desirable properties of a primary refrigerant. Without being pressureregulated, primary refrigerants absorb all available heat from perishable goods until theyre frozen solid. This data is necessary for designing the pumping units of the system. The thermodynamic efficiency of a refrigeration system depends mainly on its operating temperatures. Refrigeration n changes phase due to change in pressure n most common cryogens are n solid carbon dioxide n liquid carbon cook chill systems n used to replace warm holding of foods n cook chill system. Classification can be divided into class 1, class 2, class 3. However, the compressor must use a synthetic polyester lubricating oil. All refrigerants which damage the ozone layer have now effectively been banned, however many substances have a significant gwp that is released into the atmosphere through leakage. R4a is capable to be at temperatures of 28c at room temperatures of 38c, its performance being very similar to that of an r12.
This paper presents the investigation results of hfc refrigerants r125, r143a, r152a and r32 which prevent the ozone layer. System should possess some desirable properties like the refrigerant should be more volatile than the absorbent in other words the boiling point of refrigerant should be much lower than the absorbent. Key properties of the main refrigerants are given in together with their typical application ranges. A refrigerant with a lower boiling point tends to have a better ability to cool. Following are the desirable properties of a primary refrigerant. Jul 17, 2017 a refrigerant with a lower boiling point tends to have a better ability to cool. Thermodynamic properties of duponttm freonr 22 refrigerant author. Ammonia is highly toxic but it has excellent thermal properties and low volumetric displacement. Low boiling temperature at atmospheric of the refrigerant is desirable. This liquid, sweet, colorless refrigerant has a nonirritating odor, is nonflammable and nontoxic. Table a1 molar mass, gas constant, and criticalpoint properties table a2 idealgas specific heats of various common gases table a3 properties of common liquids, solids, and foods table a4 saturated watertemperature table table a5 saturated waterpressure table table a6 superheated water table a7 compressed liquid water table a8 saturated icewater vapor. This article is the brief overview of what are refrigerants and the history of refrigerants.
The thermodynamic properties of refrigerants columbushoa. Polyalkylene glycol pag soluble or partially soluble with hc refrigerants depending upon the conditions. What is a refrigerant and desired properties of a refrigerant free download as pdf file. Which of the following is not a desirable property for new refrigerants. Learn vocabulary, terms, and more with flashcards, games, and other study tools. 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. However, hcfc refrigerants r123 and r22 do not completely prevent the ozone layer depletion. Desirable properties of refrigerants desirable refrigerants are those which possess chemical, physical, and thermodynamic properties that permit their efficient application and service, in practical designs of refrigerating equipment. If the oil has to be in the system it is of great importance that the lubrication issues are taken care of early.
Refrigerants are classified according to their way of absorption or extraction of heat from substances stored in the refrigerator. The method used to solve for new refrigerants was achieved using an iterative method based on group contribution theory. Dec 12, 2005 this article has been excerpted from a comprehensive white paper, refrigerants for commercial refrigeration applications, issued by copeland corp. Polyol ester poe generally exhibit excessive solubility with hc refrigerants. The refrigerants should be chemically stable as long as they are inside the refrigeration system. The following is a list of refrigerants with their typeprefix, ashrae designated numbers, iupac chemical name, molecular formula, cas registry number blend name, atmospheric lifetime in years, semiempirical ozone depletion potential, net global warming potential over a 100year time horizon, occupational exposure limitpermissible exposure. It is highly toxic but nonexplosive and nonflammable. Ozone depletion potential odp of a chemical compound is the relative amount of degradation it can cause to the ozone layerglobal warming potential gwp is a measure of how much a given mass of a gas contributes to global warming.
With regard to environmental impacts, the preferable refrigerant is butane. Properties of a good refrigerants mechanical engineering. They finally chose dichlorodifluoromethane freon as having the most desirable characteristics, thus introducing the first chlorofluorocarbons. Examples of secondary refrigerants include water, air, hydrocarbons, ammonia and carbon dioxide, which are more environmentally benign than traditional refrigerants such as hcfcs. Refrigerants such as air, water and carbon dioxide are used but most refrigerants are those designed for vapour compression cycles.
A blend of ab and m oils achieving desirable properties for use with hc refrigerants. The text, which contains worked examples, is intended for use as an elective undergraduate paper for 3rd or 4th year engineering students. This property of refrigerant in both states carries importance for calculating heat transfer coefficients in evaporators and condensers. The flood of the airconditioner, that is, the refrigerants, their properties, merits and demerits are summarized to map the various types and their classifications. Refrigerants are divided into groups according to their chemical composition.
Equipment and system dehydrating, charging, and testing 9. Thermophysical properties of refrigerants t his chapter presents data for thermodynamic and transport properties of refrigerants, arra nged for the occasional user. Pdf refrigeration and airconditioning play a vital role in domestic and industrial. Refrigerants and their application presented by thomas e. Common refrigerants and their ozone depletion potential odp and global warming potential gwp are indicated below. Low boiling point otherwise operation at high vacua becomes a necessity low condensing pressure to avoid heavy machine plant scantling and reduce the leakage risk. Naturally, refrigerants with as a low a value of tewi are preferable from global warming point of view. Ashrae position document on refrigerants and their responsible use 5 a broad range of fluids has been used as refrigerant over the past century, and the current usage is dominated by a range of fluorinated chemicals, such as hfcs, in addition to hydro. Refrigerants color codes refrigerants and their color codes.
585 939 1116 1225 627 356 795 1088 1468 1280 1012 1395 723 1491 1095 1009 1519 427 1292 737 1498 1367 30 1529 661 1462 907 571 463 22 329 1077 173 346 1272 294 1393 1491 1092 1426 1377 1173