Characteristics Of Vapour Compression Refrigeration Cycles Engineering Essay

Characteristics Of Vapour crush Refrigeration Cycles Engineering EssayThis intent is a study on a performance of a dehydration condensate Refrigeration establishment VCRC. The performance of this shell of infrigidation agreement is being investigated by development different type of elaboration valves or to a fault know as throttling valves. I am victimization three types of valves upon conducting this study which atomic number 18 thermostatic expansion valve, capillary subway system expansion valve and constant- shove level expansion valve. Performance of infrigidation systems go away be investigated on 2 kind of surrounding which argon closed and open surrounding. A light bulb volition act as a modify hinderance which willing increase the ingress temperature of commit on e drying upation. This nominate also discuss about the ideal application program of each type of expansion valves. Which mean, where, when and what application the three types of expansion val ves should be use for a better result.Refrigeration is the action of alter, and in practices this waits removal of light and discarding it at superiorer temperature. Therefore, refrigeration is a science of moving alter from pitiable temperature region to the high temperature region.Refrigeration can be defined as a process of achieving and maintaining a temperature be humble that of the surroundings, with the aim to cool about product or space to the demand temperature. The most important applications of refrigeration are the preservation of perishable food products. Refrigeration systems also apply for providing thermal comfort to gentlemans gentleman beings by utilise fashion conditioning. rail line Conditioning refers to the treatment of straining so as to simultaneously reserve its temperature, moisture content, cleanliness, odor and circulation, as required by occupants, a process, or products in the space. The subject of refrigeration and air conditioning has e volved out of human select for food and comfort, and its history dates back to centuries.In refrigeration system, awake must be re locomote from the space area specific eachy the goods or matter we need to cool and released to the environment. Nature of heat movement is, heat always moves from the hotter to the colder space. To transfer heat from hot region to cold region, limited device is required. The device is called icebox. Refrigerator is a cyclic device and it is employ a fluid called cold as a working fluid.As known there are two common methods for refrigeration which are natural and mechanical. In natural refrigeration, ice is employ to generate a circulation of air around the blocks of ice. Therefore some of the heat from the circulating air is transferred to the ice so chill the air. This method particularly used in air conditioning application. As in mechanical refrigeration, refrigerating is used as a working fluid. Refrigerant is a substance that is adequate to(p) to transfer heat that it absorbs at low temperatures and pressures to a condensing medium. Refrigerator is an ex angstrom unitle of mechanical refrigeration.In a refrigerator, coolant is cooled in a electrical ability from there it flow to the evaporator, where air is cooled by contact with the c oil color. picture specimen of Refrigerator 2006 Publications International, Ltd.Types of refrigeration circle evaporation Compression Refrigeration SystemVapor compression refrigeration system is the most common refrigeration system used nowadays. In vapor compression refrigeration cycle (VCRC), there are four major thermal process matter place which is expansion, evaporation, compression and condensation. In all practical applications, the actual VCRC is land than the ideal cycle. This caused by several factors such(prenominal) as friction losses, heat exchanges amid parts on the system and pressure overtops in suck and discharge lines.http//t2.gstatic.com/ emblems?q=tbnA Nd9GcT-X7cy0Nn5FpUh23SVRaPzAFG_o0lp2WxOEMmReUZSPjiYERUt=1usg=__BGAiwbpSspuI0lSI-ZibGb3mh0Q=Figure exclusive demo VCRC The Full wiki/ refrigeration cycle found on Figure 2, compression process is done on compressor followed by condensation process on condenser, expansion process on expansion valve and lastly evaporation process on evaporator.Compression carry out on CompressorLow-pressure vapor of refrigerant enters the compressor and thence being compressed and moved to condenser as a high-pressure vapor (superheated).Condensation Process on CondenserThe superheated vapor of refrigerant is then travels by means of the condenserwhich first cools and terminates the superheat and then condenses the vapor refrigerant into a liquid refrigerant by removing additional heat at constant pressure and temperature. intricacy Process on expansion ValveThe liquid refrigerant is then goes through with(predicate) theexpansion valvewhich is also known as throttling valve where its pressure wi ll abruptly decreases, causingflash evaporationand auto-refrigeration of, typically, less than half of the liquid. By undergoing expansion process, mixture of liquid and vapor refrigerant is produced at low temperature and pressure.Evaporation Process on EvaporatorThe cold liquid-vapor refrigerant is then travels through the evaporator coil or tubes and it is completely vaporized by cooling the warmly air (from the space being preserve) and being blown by a fan across the evaporator coil or tubes. The resulting refrigerant vapor returns to the compressor inlet to complete the thermodynamic cycle.Vapor compression refrigeration system using high-grade energy such as mechanical work. It has more than affray and wear is possible to occur in the compressor since moving parts is put there. Coefficient of performance, COP of VCRC will decrease if the pressure of the evaporator decreases. Performance of VCRC is adversely alter at partial load.Vapor Absorption Refrigeration SystemVapo r Absorption Refrigeration Systemuses a heat source such as solar and kerosene-fueled flame to provide the energy needed to impel the cooling system. Vapor submergence Refrigeration system is a favorite alternative to repaircompressor refrigeratorswhere electricity is unreliable, costly, or unavailable, where noise from the compressor is problematic, or where superfluity heat is available such as from turbine vanquish or industrial processes. Absorption refrigerators powered by heat from thecombustionofliquefied vegetable oil botchare often used for food storage inrecreational vehicles.There are two type of vapor absorption refrigeration system that is single- order and double effect. Single-effect absorption system is using neither ammonia or peeing while double-effect absorption system uses atomic number 3 cliche or water supply.Since the presence of ammonia or lithium bromide directly into a confined space which is full of human is dangerous, vapor absorption system whi ch used this material should be placed away the realiseing to be cooled. However, vapor absorption that using ammonia or lithium bromide is not practical to be used on a building since it is impossible to pipe this material into the building. Therefore all absorption cycle equipment is then designed to chill water which is then piped into the building.The chilled water is piped through to fan coil units in each of the instruct spaces. The application of vapor absorption system using water is indeed well suited to multiple room systems or large spaces requiring air conditioning. This is because absorption chillers are a well-established technology that can offer significant advantages over schematic, automatically goaded, vapor compression chillers.Absorption cycle is using a fluid pair rather than using a mechanically driven or an electrically powered compressor to be function. The absorption cooling cycle is driven by the heat source, such as accelerator pedal burner, trav el or hot water. This heat source is used to boil and drive the refrigerant out of the refrigerant/absorbent mixture. This mixture is commonly termed solution.The refrigerant is then going through a condenser to remove the latent heat of condensation, thus returning the refrigerant into liquid form. The refrigerant is then passed to the evaporator where evaporation process draws heat from the recirculating chilled water. The resulting vapor from the evaporator is attracted and absorbed by the absorbent solution to complete the cycle. In effect, the mechanical compressor of a conventional vapor compression cycle has been substituted with a chemical pump driven by heat.http//www.acr-news.com/news/images/651_2.jpgFigure Single Effect Absorption modify ACR News locomote pip-squeak Refrigeration systemSteam Jet Refrigeration system is using the principle of liquids flashing under void in a chamber. If the flash vapor removed from the chamber, the liquid will cool to the required temperature. In practice, more than one cooling stage is usually present. Steam Jet Refrigeration system will move more economical when both go and cooling water is promptly available. Steam thousand refrigeration system working start with the steamerer passed through avacuum ejectorof high talent to exhaust a separate, closed vessel which forms part of a cooling water move. The partial vacuum in the vessel causes some of the water to evaporate, thus giving up heat throughevaporative cooling. The chilled water is wield through the circuit to air coolers, while the evaporated water from the ejector is vulcanised in separatecondensersand returned to the cooling circuit.Insteam jet refrigeration systems, water can be used as the refrigerant. Water is abruptly safe for human. These kinds of systems were applied successfully to refrigeration in the early eld of century. At low temperatures the saturation pressures are low (0.008129 bar at 4C) and the specific volumes are high (157.3 m3/kg at 4C). The temperatures that can be attained using water as a refrigerant are not low enough for most refrigeration applications scarcely are in the range which may satisfy air conditioning, cooling, or chilling requirements. These systems also used in some chemical industries for several processes, such as the removal of paraffin wax from lubricating oils. The application of steam jet refrigeration system also including cooling a hot corrosive liquid efficiently to any desired temperature and the cooling of fruit juices instantaneously.Note that a steam jet refrigeration system is not suitable to be used when the required temperatures are below 5C.Steam jet refrigeration systems use steam ejectors to reduce the pressure in a tank containing the return water from a chilled water system. The steam jet ejector utilizes the energy of a fast-moving jet of steam to capture the flash tank vapor and compress it. Flashing a portion of the water in the tank reduces the liquid temperature. High-pressure steam expands while flowing through the nozzle 1. The expansion causes a drop in pressure and an enormous increase in velocity. Due to the high velocity, flash vapor from the tank is drawn into the swiftly moving steam and the mixture enters the diffuser. The velocity is gradually reduced in the diffuser but the pressure of the steam at the condenser is increased 5-10 times more than that at the entrance of the diffuser (e.g. from 0.01 bar to 0.07 bar).The main advantages of this system are the utilization of mostly low-grade energy and relatively small amounts of sleep together work. Using Steam Jet refrigeration system will required negligible maintenance and a plant can be fabricate in any suitable material of construction. In steam jet refrigeration system, there is no moving part involved.http//www.siit.tu.ac.th/image/4ref.jpgFigure Steam Jet Refrigeration System Sirindhorn International Institute of Technology, Thammasat University thermoelectrica l Refrigeration SystemAn effect of refrigeration can also be achieved without using any moving parts. This is done by simply spill a small stream through a closed circuit which is made up from two variant metals. This type of effect is called the Peltier effect, and a refrigerator which is works using this kind of principle is called a thermoelectric refrigerator.The thermoelectric device is like the conventional thermocouple. It is using two dissimilar materials as a medium to transfer heat from one another. In a thermoelectric refrigerator, there are two pairing between the two different metals used. One junction is placed in the preserve space and the other one is placed in the ambient surrounding. The temperature of the junction which is located in the refrigerated space will decrease when the current passed through and create a potential difference. An opposite effect will occur on the other junction.Under steady-state drag conditions, heat is transferred from the refrige rated space to the cold junction. The other junction will be at a temperature above the ambient, and heat will be transferred from the junction to the surroundings.http//china-heatpipe.net/up_files/image/2008-4-24/826639119.jpgFigure Thermoelectric Refrigeration EffectThe thermoelectric refrigeration effect are too expensive for a normal domestic and commercial-grade applications which are run only on using a regular household current. This concept normally suited to recreational applications due to the clog of thermoelectric refrigerator which is light, compact and it is also insensitive to motion or tilting. This type of refrigerator also has no moving parts, and can prevail directly from 12-volt batteries.Using thermoelectric refrigerator will give a advantages to the food and beverages. It will keep the food and beverages cold and dry. There also no wasted space for ice. The advantages of thermoelectric refrigeration system takeCompact sizeVery little space is required by t he cooling system.LightweightCan be carried with one hand loudUse Low Battery to be function.Comparison between refrigeration systemFeatureRefrigeration SystemCompressionAbsorptionSteam JetPrinciple of coolingVaporizing a RefrigerantVaporizing an Ammonia gasSource of EnergyMechanical workHeatCompactness burdenPortabilityHeavyMust be kept level within 2-3 degrees determineBattery DrainDraw more current when running6.5-7.5 ampCooling PerformanceMost efficient in hot liveLess efficient at high ambientFreezing frappe cubes in hot weatherexcellentNot practical recourseLeaking of refrigerantLeaking of refrigerantReliabilityExposed to wearand may require expert servicing from time to timeService Maintenance undeniable trained mechanics and special service equipmentComponents on Vapor Compression Refrigeration CycleVapour compression refrigeration system lie in of several mechanical components that helps the systems to be function. Four major components on drying up compression refriger ation system include compressor, condenser, expansion valve and evaporator.In survival of any components on refrigeration system, there are many factors that we need to consider very carefully, that isMaintaining total refrigeration availability while the load varies from 0% to 100%Frost control for continuous performance application. mutation in affinity of oil for refrigerant caused by large temperature changes, and oil migration outside the compressor crankcase. excerption of cooling medium.Direct expansion refrigerant gloominess or pump recirculated or flooded refrigerant.Secondary coolan (e.g. brines, salts and glycol)System efficiency and maintainabilityType of condenserAirWaterEvaporatively cooledDesign of the compressorOpen tightSemihermetic motor driveReciprocatingScrewRotaryType of systemSingle stageSingle economizedCompound or cascade arrangementSelection of refrigerant.Type of refrigerant basically chosen based on operating temperature and pressure.CompressorCompressor is one of the major components on refrigeration system. There are two main functions of compressors in the refrigeration cycle. The first one is to pump the refrigerant vapour from the evaporator so that the desired temperature and pressure can be maintained in the evaporator. The second function is to increase the pressure of the refrigerant vapour through the process of compression, and simultaneously increase the temperature of the refrigerant vapour. Therefore the pressure will change and make the superheated refrigerant flows through the systems.Compressor also known as the heart of the vapour compression refrigeration system because it is supplied energies to run the system. Compressor can be divided into two main categories which are shift compressors and dynamics compressors. Both displacement and dynamics compressors can be hermetic, articulated lorry hermetic or open types. Both compressors also pumps refrigerant passim the systems and produce substantial increase in th e pressure of the refrigerant.Displacement CompressorsThese types of compressors used a shaft work to increase the refrigerant pressure by reducing the compression volume in the chamber. Reciprocating compressors, vane ( orbitual) compressors and helical rotary (scroll) compressors are including in a group of displacement compressors.Reciprocating compressors compress the refrigerant gas only on forward stroke. A piston is build to be single acting in a large capacity range up to hundreds of kilowatts.Condenserelaboration ValveEvaporatorRefrigeration Cycle blowup valve selectionThermostatic Expansion valveCapillary Tube Expansion valveConstant-pressure Expansion valveRefrigerantTypes of refrigerantCharacteristics of refrigerantsSelection of refrigerantPerformance of Vapor Compression Refrigeration CycleCHAPTER 2LITERATURE REVIEWCHAPTER 3 observational METHODOLOGYIntroductionBackground of StudyParameters InvolvedEquipments and Apparatus congeal upStandard Operating ProcedureCHAPTER 5 RESULT AND DISCUSSIONSCHAPTER 6 CONCLUSION AND RECOMMENDATIONSREFFERENCES