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The performance of heat transfer is one of the most important research areas in the field of thermal engineering. There are a large number of refrigerants, which are used to transfer heat from low temperature reservoir to high temperature reservoir by using vapour compression refrigeration system. There are various obstacles faced in working of different refrigerants due to their environmental impact (R11, R12), toxicity (NH3), flammability (HC) and high pressure (CO2); which makes them more hazardous than other working fluids according to safety and environmental issues. Here experimental study is conducted to observe the performance of different environmental friendly refrigerant mixtures (HC mixture and R401a). It is also observed the effect of working parameters like diameter of capillary tube, working pressures and inlet water temperatures, which affect the coefficient of performance (COP) of vapour compression refrigeration system. It is observed that R134a is more efficient than HC mixture and R401a, but there is less mass quantity of HC mixture and R401a is required in the same system. So there is less effect in environment due to more mass of R134a.
Present day mankind depends very heavily on refrigeration and air conditioning systems for daily needs. These cover a wide range of applications such as food processing, comfort cooling, health and recreation etc. Refrigerants are the working fluids for refrigeration and air conditioning systems. Generally refrigerants are classified into various types on the basis of their physical and chemical changes during the course of operation. The most preferred type of the refrigerant mixture is zeotropic mixtures. Refrigerants emit green house gases and these gases have a significant impact on the environment. Global warming and ozone depletion are the most important environmental issues caused by the refrigerants. Refrigerants are the derivatives of alkanes namely methane and ethane. Chloroflurocarbon, hydrochloroflurocarbon, hydroflurocarbon and hydrocarbon are the major chemical compounds which are used as refrigerants since 1970s. The presence of chlorine and fluorine in the derivatives of methane and ethane modifies the emission of green house gases and their impacts. The present study deals with the drawbacks of existing refrigerants and also finding a suitable replacement to the presently used working fluids with respect to their chemical compositions, thermodynamic properties and environmental properties. The results obtained from this study supported that the blend of R410A (CH2F2/C2HF5:50/50 by mass)/R600a (C4H10) as a potential replacement for R22 (CHClF2). Keywords:Refrigerants, chemical composition, thermodynamic properties, ozone depletion, global warming
The performance of heat transfer is one of the most important research areas in the field of thermal engineering. There are a large number of refrigerants, which are used to transfer heat from low temperature reservoir to high temperature reservoir by using vapour compression refrigeration system. There are various obstacles faced in working of different refrigerants due to their environmental impact (CFC, HCFC), toxicity (NH3), flammability (HC) and high pressure (CO2); which makes them more hazardous than other working fluids according to safety and environmental issues. Experimentation is conducted to observe the performance of Hydro-fluorocarbon (HFC) refrigerants (R134a and R152a) in vapour compression refrigeration. Value of average refrigerating effect for R152a is about 57% more than that of R134a . Average pressure ratio for R152a was 18.92% higher than that of R134a. In this result, R152a has emerged as the most energy efficient refrigerant among both the investigated refrigerants being the one that exhibited the lowest power consumption per ton of refrigeration with the average value of 13.23% less than that of R134a.The COP of R152a obtain is higher than R134a by 3.769% .As a result, R152a could be used as a drop-in replacement for R134a in vapour compression refrigeration system. R152a offers the best desirable environmental requirements; zero Ozone Depleting Potential (ODP) and 120 Global Warming Potential (GWP).
_______________________________________________________________________________________ Abstract The (HFC) that is hydro fluorocarbon replaces the (CFC) that is chloro fluorocarbon and (HCFC) that is Hydro chloro fluorocarbon refrigerants. HFC is being considered because concern about depletion of the ozone layer and global warming. There are numerous research has been done which suggested various alternative of refrigerants Twenty one refrigerants (R32 as R22, R290, R502, R407C, R410A and R417a etc.) have been considered for investigating thermal performances and model was tested by for 40oC condenser temperature and-40oC evaporator temperature for 3.5167 kW cooling capacity of system. The eco-friendly refrigerant also considered because of its zero ODP(ozone depletion potential). In case of R22 its ODP is 0.055., which have harmful effects on ozone layer. Therefore R22 will phase out form earth by 2030 in developed countries and by 2040 in developing countries. The vapour compression refrigeration system using alternate refrigerant needs to be modify or due to variation in the properties (physical and chemical) of these alternate with R22. The hydrocarbons R600 , R600a and R 290 are flammable in nature and R 502 is azeotropes refrigerants are also been considered for numerical computation at 40oC reference temperature (for typical Indian conditions). In the present work exergy analysis along with energy analysis of vapour compression refrigerant cycle for CFC refrigerants (R12, R22, R502) and its 18 alternate refrigerants (i.e.R 407C, R410A and R417A etc) has been carried out for evaporator temperature between-40℃ and condenser temperature of 40℃,. The parametric investigation such as coefficient of performance , exergy destruction in terms of lost work , exergetic efficiency, and efficiency defect in individual components for above refrigerants have been carried out theoretically and have been compared with the available data [10]. The result indicates that evaporating and condensing temperature have pronounced effect on exergy destruction in the components such as compressor, condenser and throttle valve .The exergetic efficiency and COP of the cycle change to large extent with the variation in evaporator and condenser temperatures and it was observed that eco-friendly refrigerant R152a have maximum first and second law performances.
The existing refrigerant requirements are, system performance should not be compromised, refrigerant and lubrication interaction should be as required, it should be energy efficient, environment friendly etc. After Montreal protocol, use of refrigerants like CFC and HCFC banned because of high ozone depleting potential (ODP). So there is need to find out a refrigerant which is environment friendly, such as HFC refrigerants as working fluids in refrigeration and air conditioning systems and which can be used long term substitute for existing refrigerants. The most important qualification for refrigerants is low ozone depleting potential (ODP). HFC refrigerants have suitable specifications such as non-flammability, stability, and similar vapour pressure to the refrigerant CFCs and HCFCs and zero ozone depleting potential (ODP). They are used in many applications with safety of the leakage from the system also with these refrigerants it was found that, there was no need to change in the design of the refrigeration system. So we can look forward to HFC refrigerants. R407C and R507 are HFC refrigerants which are under study.
Scientific Journal of Maritime Research
Thermodynamic study of environment-friendly R429A, R435A and R457A refrigerants as substitutes for ozone depleting R22 in refrigeration and air-conditioning systems2017 •
International Journal of Engineering Research and Technology (IJERT)
IJERT-Comparative Performance of R438A and R32/R125/R600A Mixture for Replacing HCFC22 used in Air-Conditioners2015 •
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A THEORETICAL COMPARISON OF TWO ECO-FRIENDLY REFRIGERANTS AS ALTERNATIVES TO R22 USING A SIMPLE VAPOUR COMPRESSION REFRIGERATION SYSTEM2014 •
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ENERGY PERFORMANCE OF ECO-FRIENDLY RE170 AND R510A REFRIGERANTS AS ALTERNATIVES TO R134a IN VAPOUR COMPRESSION REFRIGERATION SYSTEM2012 •
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International Journal of Engineering Sciences & Research Technology
Alternative Refrigerants: A Review2014 •
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