Low viscosity of the refrigerant in both states are desirable. Safety properties of refrigerants considering flammability and toxicity are defined by ashrae standard 34 1. The primary refrigerants used in commercial reachin and walkin coolers are r404a and r4a, greenhouse gases with global warming potentials gwps in excess of 1,400. What is a refrigerant and desired properties of a refrigerant scribd. This article is the brief overview of what are refrigerants and the history of refrigerants. Learn the types of refrigerants bright hub engineering. It has long been used in a variety of airconditioning and refrigeration applications in a variety of. The september 2017 addendum 1 has been incorporated into the already published 2017 version of. 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. R4a is capable to be at temperatures of 28c at room temperatures of 38c, its performance being very similar to that of an r12. Examples of secondary refrigerants include water, air, hydrocarbons, ammonia and carbon dioxide, which are more environmentally benign than traditional refrigerants such as hcfcs.
Here are some of the desirable properties of refrigerant explained in detail. Thermodynamic properties of duponttm freonr 22 refrigerant. 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. The process is not easy, and although there are alternatives to old refrigerants, the new ones are usually not. With regard to environmental impacts, the preferable refrigerant is butane. A blank numerically shows the thermodynamic properties of a refrigerant under saturated conditions. Desirable properties of refrigerants chemical engineering site. This paper presents the investigation results of hfc refrigerants r125, r143a, r152a and r32 which prevent the ozone layer. 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. 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. Refrigerants are divided into groups according to their chemical composition. The flood of the airconditioner, that is, the refrigerants, their properties, merits and demerits are summarized to map the various types and their classifications.
High latent heat of refrigerant at evaporator temperature is desirable. The production and use of cfcs is restricted by the montreal protocols. If the oil has to be in the system it is of great importance that the lubrication issues are taken care of early. Refrigerants with higher boiling points tend to be more efficient and may work well in a smaller machine. Polyalkylene glycol pag soluble or partially soluble with hc refrigerants depending upon the conditions. Usually, a fluid, used in a heat pump and refrigeration cycle that can extract heat from another body or substance. These refrigerants will evaporate at cold temperatures and so the heat absorbed is in the form of latent energy. Properties of a good refrigerants mechanical engineering. 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. 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.
Chlorofluorocarbons cfcs, hydrochlorofluorocarbons hcfcs and hydrofluorocarbons hfcs are synthetic substances used as refrigerants. R32 is a chlorinefree, ozonesafe fluorocarbon whose boiling point is 52c. In addition, if the volume of charge is large, there should be no danger to health and property in case of its escape. Nist standard reference database 23, refprop thermo dynamic properties of refrigerants and refrigerant mixtures, version 3. The method used to solve for new refrigerants was achieved using an iterative method based on group contribution theory. 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. 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. Thermophysical properties of refrigerants t his chapter presents data for thermodynamic and transport properties of refrigerants, arra nged for the occasional user. Since different fluids have the desired traits in different degree, choice is a matter of. The refrigerants have a thermodynamic property charge. Refrigerants such as air, water and carbon dioxide are used but most refrigerants are those designed for vapour compression cycles. Incorporating product design into the development of new. This also reduces the initial cost of the refrigerant used in the system.
Common refrigerants and their ozone depletion potential odp and global warming potential gwp are indicated below. The desired thermodynamic properties are a boiling point somewhat below the target temperature, a high heat of vaporization. However, the compressor must use a synthetic polyester lubricating oil. However, important practical issues such as the system design, size, initial and operating costs, safety, reliability, and serviceability etc. 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. Desirable properties of refrigerants used in refrigeration. This article presents a comparison of the properties and performance of hydrocarbons as refrigerants in smallsize heat pump and refrigeration systems of several. Naturally, refrigerants with as a low a value of tewi are preferable from global warming point of view. 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.
This section presents data for the thermodynamic and transport properties of refrigerants, arranged for the occasional users. This article describes thermodynamic properties of the refrigerants the ideal refrigerant. Control of moisture and other contaminants in refrigerant systems 8. Synthetic and organic refrigerants are classified under two main categories, primary and secondary.
In todays world, other properties of the refrigerant are more important. Jul 04, 2017 refrigerant nomenclature nomenclature of refrigerants refrigeration and air conditioning. Halocarbon refrigerants halocarbon refrigerant are all. Thermodynamic properties of duponttm freonr 22 refrigerant author. It has the highest refrigeration effect per kilogram of all refrigerants and comes at a low cost. Primary refrigerants change states to absorb heat from surrounding areas or substances. In refrigeration and air conditioning applications there are wide range of conditions in which the refrigerants.
Lets look at the properties of these and other refrigerants. The liquid has to vapourise at the evaporator coil to cause cooling. 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. The usage of oil free compressors solves many of the problems that lubricants consisting of a mixture of oil and refrigerant cause. R32 and r125 are seldom used as single refrigerants, but only in mixtures with particularly favorable thermodynamic properties. There must be large difference in the boiling points of refrigerant and absorbent greater than 2000 0c, so. Refrigerants are widely used in refrigeration cycle where cooling effect below the atmospheric temperatures are needed. Learn vocabulary, terms, and more with flashcards, games, and other study tools. A number of materials have physical and thermodynamic properties suitable for their use as refrigerants. Apr 12, 2020 refrigerants are widely used in refrigeration cycle where cooling effect below the atmospheric temperatures are needed. The text, which contains worked examples, is intended for use as an elective undergraduate paper for 3rd or 4th year engineering students. Pdf refrigeration and airconditioning play a vital role in domestic and industrial. 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.
Some comments on the refrigerants presented in the table are given below. Compressor has to be operated at high vacuum if the boiling point of the refrigerant is high at atmospheric pressure. However, hcfc refrigerants r123 and r22 do not completely prevent the ozone layer depletion. Which of the following is not a desirable property for new refrigerants. Jul 17, 2017 a refrigerant with a lower boiling point tends to have a better ability to cool. 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. Key properties of the main refrigerants are given in together with their typical application ranges. Following are the desirable properties of a primary refrigerant. Originally the title given was new and alternative refrigerants but i was also asked to. The article focuses on the criteria for refrigerant selection, including discussion of the transitional refrigerants hcfcs, chlorine free refrigerants hfcs, and halogen free refrigerants. This property of refrigerant in both states carries importance for calculating heat transfer coefficients in evaporators and condensers.
Refrigerants and their application presented by thomas e. The refrigerants should preferably be nonflammable and nonexplosive. Mixtures of r12 vapor and air, in all proportions, will not irritate your eyes, nose, throat, or lungs. May 01, 2014 following are the desirable properties of a primary refrigerant. This data is necessary for designing the pumping units of the system. 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. Ashrae position document on refrigerants and their. Without being pressureregulated, primary refrigerants absorb all available heat from perishable goods until theyre frozen solid. Safety properties of refrigerants considering flammability and toxicity are defined by. 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. 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. In fact, from the thermodynamic or heatcarrying standpoint, differences among refrigerants with similar. Positively innovative refrigerants r32 daikin chemical europe.
Ammonia is highly toxic but it has excellent thermal properties and low volumetric displacement. The thermodynamic properties of refrigerants columbushoa. For flammable refrigerants special precautions should be taken to avoid accidents. These two refrigerant thermodynamic properties are similar to each other, making it a desirable choice for future automotive refrigerants. 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. 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. Risk assessment of refrigeration systems using a2l. Some important physicalchemical properties of refrigerants. Toxic pressures to the previous refrigerant with zero odp from dupont halogen free refrigerants 09. Pdf refrigerant types, issues, trends and future options. 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. A blend of ab and m oils achieving desirable properties for use with hc refrigerants. This article has been excerpted from a comprehensive white paper, refrigerants for commercial refrigeration applications, issued by copeland corp. Whenever we choose them for particular use properties of refrigerants also plays a vital role in economic and environmental friendly application.
It is highly toxic but nonexplosive and nonflammable. Possible replacements for these refrigerants in commercial applications include ashrae class 2l refrigerants, which have lower global warming potentials but are mildly flammable. Polyol ester poe generally exhibit excessive solubility with hc refrigerants. 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. Equipment and system dehydrating, charging, and testing 9.
Refrigerant is the life blood of the vapor compression cycle. 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. The properties examined in this study were toxicity, flammability, explosion potential, global warming potential, ozone depletion potential and efficiency. The thermodynamic efficiency of a refrigeration system depends mainly on its operating temperatures. Low boiling temperature at atmospheric of the refrigerant is desirable. Refrigerant containment, recovery, recycling, and reclamation. The institute of refrigeration refrigerants americas. Duponttm refrigerants, technical information keywords. 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. 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. Table of contents 2018 ashrae handbookrefrigeration.
Refrigerants color codes refrigerants and their color codes. R32 has a gwp about one third that of r410a, and it has excellent properties. Fellow ashrae mcquay international staunton, virginia usa 1 what is a refrigerant. Toxicity classification of refrigerants is assigned to classes a or b. 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. Classification can be divided into class 1, class 2, class 3. Dec 12, 2005 this article has been excerpted from a comprehensive white paper, refrigerants for commercial refrigeration applications, issued by copeland corp. Desirable refrigerants are those which possess chemical, physical, and thermodynamic properties that permit their efficient application and service, in practical designs of refrigerating equipment. A refrigerant with a lower boiling point tends to have a better ability to cool. 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.
R22 chc1f425 and r11 cc1435f are colorless, nonexplosive, nonpoisonous refrigerants with many properties similar to those of r12. The free water apart from the dissolved water in refrigerant freezes below 0 deg c. Class a signifies refrigerants for which toxicity has not been identified. 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. R4a is also known as tetrafluoroethane cf3ch2f from the family of hfc refrigerant. This liquid, sweet, colorless refrigerant has a nonirritating odor, is nonflammable and nontoxic. What is a refrigerant and desired properties of a refrigerant free download as pdf file. Refrigerants are classified according to their way of absorption or extraction of heat from substances stored in the refrigerator. 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. They finally chose dichlorodifluoromethane freon as having the most desirable characteristics, thus introducing the first chlorofluorocarbons. 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. Refrigerants properties pdf product data summary and thermodynamic tables. The refrigerants should be chemically stable as long as they are inside the refrigeration system.
Refrigerants are substances that can be used in the refrigeration cycle of air conditioning and refrigeration equipment because of their thermodynamic properties. High conductivity of refrigerant in both states are desirable. 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. Secondary refrigerants allow the amounts of environmentally harmful primary refrigerants to be minimized and contained in a restricted area. Detailed comparison is made on first generation, second generation and third generation refrigerants, including the option of using hcs and co 2.
A refrigerant is a substance or mixture, usually a fluid, used in a heat pump and refrigeration. Pdf influence of refrigerant r4ar1234yf properties. New refrigerants to replace cfcs comprise an active area of development. Refrigerants should have low freezing point than the normal operating conditions. In fact, from the thermodynamic or heatcarrying standpoint, differences among refrigerants with similar boiling points are small. 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. Because of the similarities between r22, r11, and r12, only r12 is discussed. These physical properties of refrigerants help us select the proper refrigerant for the application as per our requirement. Mle is a method for estimating parameters of a statistical model.
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