There are a variety of ways that the refrigeration cycle can be tailored to suit an application in a better way. Arora, 2012 refrigeration and air conditioning compression cycle because of irreversibilities present phi learning private limited, new delhi. May 14, 2009 refrigeration cycle it is a well known fact that heat flows in the direction of decreasing temperature, i. Generally refrigeration systems can be classified in 3 main cycle systems which are vapor compression refrigeration system, vapor absorption refrigeration system, and gas cycle refrigeration system. Similarly, two alternative designs for the evaporator are developed and simulated.
The refrigeration cycle in the log ph diagram the refrigeration cycle in the log ph diagram the real refrigeration cycle consists of the following changes of state. The tons of refrigeration, often called the cooling load or refrigeration effect, are min. H 1 to h 2 is the adiabatic compression of the compressor for the simple refrigeration system. Analyze the actual vaporcompression refrigeration cycle. The refrigeration cycles can also be represented in a ph diagram. Air conditioning clinic refrigeration cycle one of the.
Compare refrigeration to a man in a boat with a sponge. Another type of system is known as an ejector refrigeration heat. Twostage refrigeration system gpsa, 2004 17 figure 9. It sates that heat does not flow from a low temperature body to a high temperature body without the help of an external work. If an expander had been used the line from d to a would be a vertical line.
Exergy assessments by using realtime measurements in a factory. However, as a service technician you maycontinue to come across it for years to come. Theory and applications 4 contents contents 1 introduction 8 1. Design and thermodynamic analysis of a steam ejector.
The vertical pressure axis and the horizontal enthalpy axis are omitted. Fundamentals of refrigeration thermodynamics australian. The most common refrigeration system in use today involves the input of work from a compressor and uses the vapor compression cycle. The refrigerant enters the evaporator at state 4 as a. Introduction the principle of refrigeration is based on second law of thermodynamics. This cycle is often used as a comparison cycle to describe the quality of the cyclic process. In refrigeration process, since the heat has to be transferred from a low. The direction of the cyclic process in thets diagram determines w hether this is a heat pump cycle refrigeration cycle or a work machine cycle steam power cycle. The refrigeration system consists of a simple direct expansion refrigeration cycle with an adiabatic compressor having an isentropic efficiency of 85%. Wet refrigeration cycle the expander has been substituted by a throttling valve. Jsrae, japanese society for refrigerating and airconditioning. Refrigeration cycle evaporator condenser receiver expansion device.
In the last session, we had discussed vapor compression refrigeration cycle and in todays session, we can discuss in detail the concept of refrigeration along with its definition, unit, classification of refrigerants and applications. Goals of lab to get acquainted with a vaporcompression refrigeration system to be able to use pressureenthalpy diagrams and tables to determine the c. A heat pump uses a vapour compression cycle with refrigerant 12. Modeling and investigation of refrigeration system. It readily evaporates and condenses or changes alternatively between the vapor and. Now consider a change in the evaporator pressure corresponding to a decrease in the evaporator temperature to 10c. State the difficulties with carnot refrigeration cycle section 10.
Refrigeration calculations pressureenthalpy charts are tools to use in better understanding refrigeration cycles, for judging whether the operation is normal, and for estimating the effect of change in operation. Thermodynamic calculations of vapor compression refrigeration. Analyze and perform cyclic calculations for standard vapour compression refrigeration. A reversible, adiabatic isentropic compression of the refrigerant. A theoretical comparative study on nanorefrigerant. Understanding the basic refrigeration cycle diagram also helps us to find subcooled, superheat and to troubleshoot. P, t, h, and phase changes in a vapor compression refrigeration cycle. For ease in calculation, an allowance can be made for the sun load in refrigeration calculations by increasing the temperature. Carnot cycle, here the enclosed area is a rectangle. Ph diagram representation of a dry refrigeration cycle. Take the structure image of this refrigeration cycle from figure 15, it becomes the ph diagram for engineering calculation as shown in figure 16. When you can draw a refrigeration cycle on a ph diagram, you can easily obtain the refrigerant characteristics through the diagram.
Hydrocarbons, r290, r1270 and a mixture of r290r1270 of 1585 wt % are used as dropin refrigerant to r22. The refrigeration cycle explains to us what is happening to the ac freon in each of the four components within the air conditioner units. A second law analysis is performed at the end of the study. The heat pump cycle uses an ideal cycle with an evaporator at 5oc and a condenser. In the ultra low temperature field today the use of a compound system has given way to the cascade system almost 100%. This is equivalent to 12,000 btuhr 288,000btu 24 hours today, we still refer to 1 ton of refrigeration as 12,000 btuh. Ts and ph diagrams for an ideal vaporcompression refrigeration cycle. Compression refrigeration cycle the vaporcompression refrigeration is the most widely used cycle for.
Kolmetz handbook of process equipment design refrigeration. The more complete the information, the better the calculation. However the vapor compression refrigeration system is the most widely used in the. All of the relevant parameters are instrumented and the unit is completely safe for operation by students. Lesson 1 basic refrigeration cycle and concepts, standard rating of refrigerating machines 58 lesson 2 elementary vapour compression refrigeration cycle 912 lesson 3 representation of vapour compression refrigeration cycle on pv, t and ph diagrams, use of refrigerant properties tables and ph mollior charts. Air conditioning clinic refrigeration cycle one of the trane. Threestage refrigeration system gpsa, 2004 18 figure 10. The saturated vapor at state 1 is superheated to state 2. Yeah, it seems complicated at first, but it will be easier to understand. This module examines refrigeration and heat pump systems and identi. The above figure shows the objectives of refrigerators and heat pumps. Refrigeration is the achievement of temperatures below that of the local environment.
Pdf simulation of a simple vapourcompression refrigeration. Pdf on apr, 2018, hayder lafta published refrigeration load calculation find, read and cite all the research you need on researchgate. The liquefaction of the hot refrigerant vapor takes place in several stages. In the log ph diagram the pressure p is plotted above the p enthalpy h. All the important parameters use in the guideline are explained in the definition section which help. The purpose of a refrigerator is the removal of heat, called the cooling load, from a lowtemperature medium. Onestage refrigeration system gpsa, 2004 16 figure 8. Entropy for a carnot cycle coupled to a heat sink and heat. Part of this chapter deals with a refrigerant r22 that will soon be phased out of production.
The main purpose of refrigeration is thermal conditioning e. The refrigerants generally used for this purpose are ammonia nh 3, carbon dioxide co 2 and sulphurdioxide so 2. The equipment used for removing the heat continuously for maintaining a low temperature in a space is called refrigerator. Micro refrigerator, electronic cooling, micro evaporatorcondenser, microchannels, vapor compression refrigeration cycle. Refrigeration machinery and required ventilation ventilation required for refrigeration machinery and compressors in hot areas tons cooling vs. The refrigeration cycle in the log ph diagram the distinctive feature of the refrigeration cycle is that it runs counterclockwise, i. Due to this heat transfer, water vaporizes in a, flows to b and is absorbed by. Pdf vapour compression refrigeration shubham maurya. Since the water temperature in a is lower than the surroundings, a refrigeration effect qe can produced by transferring heat from the surroundings to water at 10oc.
Include in this guideline is a calculation spreadsheet for the engineering design. Sep 03, 2008 the idea refrigeration cycle imposed on the ph diagram. Case1 the basics of refrigeration cycle ph diagram analysis. Nov 06, 2016 the vapor compression refrigeration cycle is the most common method used for removing heat from a lower temperature level to a higher temperature level using a mechanical work. Refrigeration fundamentals heatcraft worldwide refrigeration. Schematic diagram of the vapor compression refrigeration cycle. The evaporator is a heat exchanger, typically of the shellandtube configuration in mining refrigeration plant. Describe the difference between single stage and two stage compression systems 6 during this presentation, we will discuss ammonia and its uses. Airflow and duct sizes typical relations between tons cooling, air flow and duct size.
Also, a new definition for the exergoeconomic factor is introduced which suggests that the components of refrigeration cycle and combustion chamber have the lowest values of the. Good calculations are the first step in assuring adequate selection in refrigeration equipment for. Elementary vapour compression refrigeration cycle 2. Ts diagram for the vapour compression refrigeration cycle including the isentropic efficiency. Th movement cooling by the removal of heat the movement of heat from a place where it is notot a ted to a wanted to a place where it is unobjectionable. The specific volume a for the refrigerant is read from the l.
Figure 6 pressureenthalpy diagram of an ideal refrigeration cycle. It tells us how much refrigerant the evaporator absorbs, the refrigerant properties in the compressor, and how much refrigerant the condenser rejects. Show the cycle on a ts diagram with respect to saturation lines. Heat transfer in refrigerator condensers and evaporators. Refrigeration and air conditioning pdf book agrimoon. Twostage refrigeration system temperature of refrigeratore04 dew point temperature of propane at 5. The points which are required for engineering calculation are from h 1 to h 6 as shown in the figure 16. This tutorial on refrigeration cycles steps through. Differentiate directexpansion, gravity flooded, and liquid overfeed evaporator arrangements 4. A refrigeration system is a combination of components and equipment connected in a sequential order to produce the refrigeration effect. Temp pressure volume energy enthalpy entropy quality.
A set of computerbased methods for calculating densities, vapour pressures, enthalpies, internal energies and entropies of refrigerants, together with simple refrigeration cycle calculations are. This amounts to 40% of the energy supplied in the fuel. However, for large industrial applications efficiency, not simplicity, is the major concern. If the walls of the refrigerated space are exposed to the sun, additional heat will be added to the heat load. The compressor is driven by a heat engine with a thermal efficiency of 40%. The hilton refrigeration laboratory unit r714 has been designed to allow students to fully investigate the performance of a vapour compression cycle under various conditions of evaporator load and condenser pressure. Heat removed from the engine in the cooling system is recovered. Refrigeration cycles the vapor compression refrigeration cycle is a common method for transferring heat from a low temperature to a high temperature. The ordinary vaporcompression refrigeration systems are simple, inexpensive, reliable, and practically maintenancefree. Goals of lab to get acquainted with a vaporcompression refrigeration system to be able to use pressureenthalpy diagrams and. This tutorial on refrigeration cycles steps through calculations neede. The cooling calculator includes an advanced calculation method for refrigeration systems, based on calculation rules suggested by ashrae, refrigerant properties by refprop from the nist and updated thermodynamic correlations for the calculation of heat transfer coefficient. Refrigeration cycle apparatus observation and calculations sr. Basic refrigeration cycle and concepts, standard rating of refrigerating machines lesson 2.
Mechanical refrigeration works by changing the the majority of heat is removed from the the majority of the works by removedchanging the absorbed heat is state of the refrigerant. Basic components of the vapour compression cycle figure 18. Learning how to read the charts and to do the calculations involved will pay rich dividendsin all phases of refrigeration work. An irreversible throttling process in which the temperature and pressure decrease at constant enthalpy. Figure 7 l f d diagram of a real refrigeration cycle. The resistance of the heat exchanger tube is a function of the thickness of the tube s, the conductivity of the tube k, and the mean cross 2. With applications to general and specialty areas, 7th edition emphasizes patient safety above all else. Modifying the conventional cycle configuration can offer a less complex and less costly alternative approach.
Economizing is a common modification for improving the performance of the refrigeration cycle, resulting in decreasing the work required to compress the gas per unit mass. The primary radiation factor involved in the refrigeration load is heat gain from the suns rays. Using 32f water for the cooling instead of ice would have required 144 tons or 288,000 lbs. It raises the pressure, temperature and enthalpy of. Cop refrig q l w in q l q h q l 1 q h q l 1 1 t s 4 s 1 t s 3 2 1 1 t h t l h1 t l t t l cop heat pump q h w in q h q h q l 1 1 q l q h 1 1 t l t h t h t h t l 2. Vapour compression refrigeration cycle ph diagram explain the vapor compression cycle on the ts and ph diagrams for the heated steam at the end of the compression the ph and ts vapor compression cycle for a simple steam compression cooling cycle is shown in the pattern for the steam entering the compressor, is in a dry state of saturating dry.
Heating and cooling buildings accounts for 40% of total energy consumption in the u. Although each separate part covers a specific area of refrigeration theory and practice, each successive publication presumes a basic understanding of the material presented in the previous sections. At the outlet of the compressor, if isentropic efficiency is 1 and the refrigeration cycle is ideal, s 1 and s 2 must be equal. Analyze and perform cyclic calculations for carnot refrigeration cycle section. Refrigeration fundamentals 2175 west park place blvd. Vapour compression cycle is an improved type of air refrigeration cycle in which a suitable working substance, termed as refrigerant, is used. Part 1 fundamentals of refrigeration part 2 refrigeration system components part 3 the refrigeration load part 4. The basic refrigeration cycle for beginners if you are interested in learning how a refrigeration system works, it is helpful to understand from the ph pressure enthalpy chart perspective. Consider a simple saturation cycle 1234 with freon 12 as the refrigerant as shown in figure 2. The vapor compression refrigeration cycle is a common method for transferring heat from a. Pdf a simple approach to calculateminimize the refrigeration.
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