CHAPTER 1 INTRODUCTION 1

CHAPTER 1 INTRODUCTION
1.1 History of Refrigerator System
Human being are looking for ways to keep their food fresh, and found out that the coldness satisfy it. Therefore the idea of refrigeration was born. For centuries people relay on ice and snow for the purpose of cooling things. Since the Roman Empire, slaves used terracotta pots fanning in water to cool down the food. That is the method of cooling by extracting heat. Until 1844, Jacob Perkins, an American inventor acquired the pattern of the first evaporative cooling refrigerator and a new chapter of refrigeration has begun. After the invention of the first refrigerator, people started to gain more and more interest in using man made machines rather than natural ice for cooling food. The early refrigerator models in the nineteenth century made the foundation of the more functional and more stylized refrigerators in the future. Many kinds of refrigerator exist in our society today, each with its own distinct function. But the refrigerator in our home is the most commonly seen and utilized. It serves primary function to keep our food fresh. This study discuss specifically on home refrigerator. Like the air conditioner, it is also consist of the following four basic components: 1.Evaporator 2.Compressor 3.Condenser 4.Expansion device. 7

Fig 1.1: Schematic diagram of a refrigeration system
1.2 Basic of Refrigeration System
Refrigerator is a cooling appliance comprising a thermally insulated compartment and a refrigeration system is a system to produce cooling effect in the insulated compartment. Meanwhile, refrigeration is define as a process of removing heat from a space or substance and transfers that heat to another space or substance. Nowadays, refrigerators are extensively used to store foods which deteriorate at ambient temperatures; spoilage from bacterial growth and other processes is much slower in refrigerator that has low temperatures. In refrigeration process, the working fluid employed as the heat absorber or cooling agent is called refrigerant. The refrigerant absorbs heat by evaporating at low temperature and pressure and remove heat by condensing at a higher temperature and pressure. As the heat is removed from the refrigerated space, the area appears to become cooler. A vapor compression cycle is used in most household refrigerators, refrigerator–freezers and freezers. In this cycle, a circulating refrigerant such as R134a enters a compressor as low-pressure vapor at or slightly above the temperature of the refrigerator interior. The vapor is compressed and exits the compressor as high-pressure superheated vapor. The superheated vapor travels under pressure through coils or tubes comprising “the condenser”, which are passively cooled by exposure to air in the room. The condenser cools the vapor, which liquefies. As the refrigerant leaves the condenser, it is still under pressure but is now only slightly above room temperature. This liquid refrigerant is forced through a metering or throttling device, also known as an expansion valve (essentially a pin-hole sized constriction in the tubing) to an area of much lower pressure. Thesudden decrease in pressure results in explosive-like flash evaporation of a portion (typically about half) of the liquid. The latent heat absorbed by this flash evaporation is drawn mostly from adjacent still-liquid refrigerant, a phenomenon known as “auto-refrigeration”. This cold and partially vaporized refrigerant continues through the coils or tubes of the evaporator unit. A fan blows air from the refrigerator or freezer compartment (“box air”) across these coils or tubes and the refrigerant completely vaporizes, drawing further latent heat from the box air. This cooled air is returned to the refrigerator or freezer compartment, and so keeps the box air cold. Note that the cool air in the refrigerator or freezer is still warmer than the refrigerant in the evaporator. Refrigerant leaves the evaporator, now fully vaporized and slightly heated, and returns to the compressor inlet to continue the cycle. 1,2,3…10

Main Component of refrigerator:
1 Compressor
2 Condenser
3 Expansion (capillary)
4 Evaporator

Fig1.2: Schematic diagram of a refrigeration system
1.2.1 Main function of each component of refrigeration system
a. Compressor:
The low pressure and temperature vapour refrigerant from evaporator is drawn into the compressor through the inlet or suction valve A, where it is compressed to a high pressure and temperature. This high pressure and temperature vapour refrigerant is discharged into the condenser through the delivery or discharge valve B.
b. Condenser:
The condenser or cooler consists of coils of pipe in which the high pressure and temperature vapour refrigerant is cooled and condensed. The refrigerant, while passing through the condenser, gives up its latent heat to the surrounding condensing medium which is normally air or water.
c. Receiver:
The condensed liquid refrigerant from the condenser is stored in a vessel known as receiver from where it is supplied to the evaporator through the expansion valve or refrigerant control valve. It is used for the constant supply of refrigerant to the evaporator.

d. Expansion Valve:
It is also called throttle valve or refrigerant control valve. The function of the expansion valve is to allow the liquid refrigerant under high pressure and temperature to pass at a controlled rate after reducing its pressure and temperature. Some of the liquid refrigerant evaporates as it passes through the expansion valve, but the greater portion is vaporized in the evaporator at the low pressure and temperature.
e. Evaporator:
An evaporator consists of coils of pipe in which the liquid-vapour. Refrigerant at low pressure and temperature is evaporated and changed into vapour refrigerant at low pressure and temperature. In evaporating, the liquid vapour refrigerant absorbs its latent heat of vaporization from the medium (air, water or brine) which is to be cooled.

Fig 1.3: Actual working diagram of a refrigeration system

Processes Involved in Vapor Compression Refrigeration System:

Fig1.4:T-S Diagram for the Ideal Vapor Compression Refrigeration Cycle

Fig 1.5 : Pressure-enthalpy graph for vapour compression refrigeration system
Process 1 – 2: Isentropic compression in compressor.
Process 2 –3: Constant pressure heat rejection in condenser.
Process 3 – 4: Isenthalpic expansion in expansion device.
Process 4 –1: Constant pressure heat absorption in evaporator.

1.3 Advantages of Vapour Compression Cycle:
C.O.P. is quite high as the working of the cycle is very near to that of reversed Carnot cycle.
When used on ground level the running cost of vapour compression refrigeration system is only 1/5 of air refrigeration system. .i.e. it has low running cost.
For the same refrigeration effect the size of the plant is smaller.
The required temperature of the evaporator can be achieved simply by adjusting the control valve of the same unit.

1.4 Factors Affcting The Performance Of VC Refrigration System
From the literature survey it is observed that following factors affect the performance of vapour compression refrigeration system.
Properties of working fluid.
Mixture proportions of different refrigerants.
Suction pressure.
Discharge pressure.
Pressure ratio.
Amount of charge filled.
Dimensions of capillary tubes
1.5 Refrigerant
1.5.1 What is RefrigerantThe working fluid used to transfer the heat from low temperature reservoir to high temperature reservoir is called refrigerant.

Different Types of Refrigerant
1 Halocarbon compound: They are molecules composed of carbon, chlorine and fluorine. They are stable, allowing them to reach the stratosphere without too many problems. It contributes to the destruction of the ozone layer. Some important halocarbon are: R11,R12,R13,R21,R22,R40,R100,R113,R114,R152
2 Azeotropes: This group of refrigerant consists of mixture of different refrigerant which cannot be separated under pressure and temperature and they have fixed thermodynamic properties.e.g.R500 is the mixture 7308% of R1226.2% of R152.

3 Hydrocarbons (HC):This is primarily propane (R290), butane (R600) and isobutene (R600a). These fluids have good thermodynamic properties, but are dangerous because of their flammability. The world of the cold has always been wary of these fluids, even if they have reappeared recently in refrigerators and insulating foams. Their future use in air conditioning seems unlikely, given the cost of setting both mechanical and electrical safety.

4 Inorganic compounds: Before the development of hydrocarbon group refrigerants, these were used in past commonly used refrigerants of his group are:R717-Ammonia(NH3),R718-Wter(H2O),R729-Air,R744,(CO2),R764-Sulphur dioxide(SO2)
5 Unsaturated organic compounds: This group of refrigerants is hydrocarbon with ethylene and propylene base. Example is: R1120-Trichloroehylene (C2HCL3), R1130 Dichlroehylene (C2H2CL2), R1150-Ethylene (C2H4), R1270-Propylene (C3H6), R1270-Propylene (C3H6). 10,12
1.5.2 CFC REFRIGERANTS
Since the 1930s, chlorofluorocarbons (CFCs) have been widely used as foam blowing agents, aerosols and especially refrigerants due to their pre-eminent properties such as stability, non-toxicity, non-flammability and thermodynamic properties. In particular, R12 has been predominantly used for small refrigeration units including domestic refrigerator/freezers. Refrigerant R12 has been the most dominant refrigerant for refrigeration industry. However, they also have harmful effect on the earth’s protective ozone layer 1. So, they are being regulated internationally by Montreal Protocol since 1989 2. Later, it was also proved that CFCs also contributed significantly to the global warming problem. The global warming potential of R12 is considered to be 8500 times that of CO2 over 100 years 3. Greenhouse gas emissions led to the Kyoto Protocol in 1997. It was thus decided that by 2010 4, producing and using of CFCs should be prohibited completely all over the world. In consequence, a lot of research has been done to find the suitable eco-friendly replacement of CFCs.

1.5.3 HCFC Refrigerant The initial alternatives included some hydro chlorofluorocarbons, or HCFCs, but they are likely to be phased out internationally around 2040, because their ozone depletion potentials and global warming potentials are in relative high levels though less than those of CFCs 5. By that time compounds such as HFCs (hydro fluorocarbons), which are benign to the ozone layer, are likely to have replaced HCFCs. As a result, it has become an urgent issue to search and develop CFC and HCFC alternatives. While the presence of single component refrigerants reduces the performance possibilities, the solution appears to lie in using the synthetic mixtures. The search for alternate refrigerants as substitutes for R134a in various refrigeration systems has been an important area of research in the RAC sector. As per the Montreal Protocol, developed countries have already phased out R12 and developing countries like India have to do the same before the end of 2010. None of the alternative refrigerants can be used in the R12 based appliances without making system modifications or technology change 6. In developing countries the growth of RAC sector has picked up momentum only in the last decade and hence the immediate change of technology may cause setbacks to the RAC sector 7.

1.5.4 R134a Refrigerant
For the past decade, R12 has been replaced with R134a in refrigerators and automobile air conditioners. At present in India more than 80% of the refrigerators are working with R134a 8. R134a
possesesfavourable characteristics such as zero ODP, non-flammability, stability and similar vapour pressure to that of R12. Earlier studies indicate that the energy efficiency of R134a obtained in actual refrigerators was lower than that of R12 9.

1.5.5 Hydrocarbon Refrigerant
Hydrofluorocarbons, such as R134a, have almost zero ozone depletion potential, as they do not contain chlorine atoms in their chemical structure. Similar to R12, they are safe, non inflammable and have similar vapour pressures 10. However, they have lower energy efficiency and are more expensive than R12. They also have a low negative environmental effect of global warming potential 11. The concern against the increase of global warming has been the prior issue of study in the present century. Thus, in 1997 the Kyoto protocol was agreed by many countries there by calling for the reduction in emissions of greenhouse gases including HFCs. The GWP of R134a is 1300 which is considerably high but lower than R12 12.
Naturally occurring substances such as water, carbon dioxide, ammonia and hydrocarbons are believed to be environmentally safe refrigerants. Now in India CFCs phase out was successfully implemented by replacing R12 with R134a, but it has to be controlled due to relatively high GWP. So, interest towards environmentally safe refrigerants is growing. At the same time the performance of the refrigerants and their flammability are other crucial factors that have to be taken into account while selecting the refrigerants. Furthermore, it is desirable that the designed refrigerants, replace the current refrigerants without any major change in the system equipment. A trade-off point between all these factors has been considered while proposing the mixtures in the present work. The aim of the present investigation is to find substitutes for R134a refrigerators. Using hydrocarbons is an environmentally sound alternative to CFCs/HFCs 13. HCs as a refrigerant have been used since the beginning of 20th century. The development of the CFCs in the 1930s placed the HC technology in the background. Hydrocarbon technology has come to the forefront. Most of the natural refrigerants are also considerably cheaper than their synthetic alternatives 14. The general conclusion is that there is no ideal refrigerant today. Natural refrigerant should be chosen whenever possible for the sake of environment protection. In fact, hydrocarbons are known to have such advantages as low cost, availability, compatibility with the conventional mineral oils as well as PAG and POE 15. However, their use has been held up in other developed countries mainly due to their high flammability. They offer other advantages of being very economical and easily available in large amounts. They are environmental friendly with zero ozone depletion potential, and they do not cause the greenhouse warming effect 16. The major limitation is that they are highly flammable substances and must be handled with caution. Also, blends of some refrigerants can be considered as substitutes or alternatives to existing refrigerants.
There are an increasing number of scientists and engineers, including environmentalists who believe that an alternative solution,
which has been overlooked, may be provided by using hydrocarbons. These provide the possibility of a zero ODP, together with suitable thermodynamic, physical and chemical properties. It is possible to mix hydrocarbon refrigerants with other alternative refrigerants, such as HFC, to replace R134a in domestic refrigerators 10, 17, 18. Alternative refrigerants should have stable thermo physical and chemical properties, good miscibility with lubricants and low inflammability. The only limitation of hydrocarbons when compared to other refrigerants is flammability. The reduction in flammability can be achieved by mixing HCs with HFCs 19. This process reduces the amount of flammable substance and consequently the flammability risk will be reduced. The global warming potential will be atleast two third less when HFCs are used alone. The proposed ternary mixture of HFC/HC used in this study has saturation properties matching with those of R134a. In fact, for the developing countries, meeting all the requirements of various international amendments for environmental protection is quite burdensome. Thus, a change in a major component in refrigeration equipment would be another serious hurdle preventing those countries from adopting energy-efficient and environmentally safe refrigerants.
It is quite likely that the first component needs to be changed in adopting a new fluid would be a compressor 6. For such a case, it would be quite costly for those who implement it to redesign and retool all the manufacturing amenities for new compressors. Thus, in order to adopt environmentally safe refrigerants at a reasonable cost, `drop-in replacement fluids’ requiring only minor changes in the system, particularly in the compressor, should be developed from the beginning to be used in the long run. In the present work, a general method of selecting `drop-in fluids’ is presented with a main application in visi cooler charged with R134a. To accomplish the goals of the study, a theoretical analysis as well as experimental investigation for the energy consumption and cooling performance is presented. The procedures and data presented in this work will be helpful for the replacement/reduction of ozone depleting/green-house warming refrigerants in the future. The point of contention surrounding the phase out of CFCs is to provide substitutes with optimum benefits and performance. In this work, an experimental study, using hydrofluorocarbon/hydrocarbon (HFC/HC) mixtures with suitable proportions, has been carried out to determine the optimum mixture for replacing R134a in existing visi coolers. Non-azeotropic mixtures have some added advantages over single component and azeotropic refrigerants. The alternatives that are proposed in this report mainly comprise of non-azeotropic mixtures of R134a and hydrocarbons.

1.6 Properties of good refrigerant
Low boiling point and high latent heat of vaporization
Non-flammable
Low toxicity
Low miscibility with oil
Low cost
Good heat transfer rate
Low freezing point
Low power consumption
High efficiency
Negligible ODP,GWP
The main objective in this study to development of Hydrocarbon blends “to study alternative refrigerants to replace R134a in a domestic refrigerator” and calculated EER, COP GWP, ODP in different methods like that practical, theoretical, software. The main function of this statistical models or use is Performance Evaluation of Domestic Refrigerator Using new eco- friendly Refrigerant as an Alternative with commonly used Refrigerant like that R32, R600a, R290, R12 And R134a.because of following reasons In India, about 80% of the domestic refrigerators use R134a as refrigerant due to its excellent thermodynamic and thermo physical properties. But R134a has high GWP of 1300. The higher GWP due to R134a emissions from domestic refrigerators Leads to identifying a long term alternative to meet the requirements of system performance, refrigerant-lubricant interaction, energy efficiency, environmental impacts, safety and service. The Kyoto Protocol of the United Nations Framework Convention on Climate Change (UNFCCC) calls for reductions in emissions of six categories of greenhouse gases, including hydro fluorocarbons (HFCs) used as refrigerants. From the environmental, ecological and health point of view, it is urgent to find some better substitute for HFC refrigerants .Many investigators have reported that GWP of HFC refrigerants is more significant even though it has less than that of chlorofluorocarbons (CFC) refrigerants .Refrigerators are identified as major energy consuming domestic appliance in household environment. Many researchers have reported that hydrocarbon mixed refrigerants is found to be an energy efficient and environment friendly alternative option in domestic refrigerators. The literature review brings out the fact that many researchers have studied with different hydrocarbon refrigerant mixtures as alternative to R12 and R134a in domestic refrigerators. However, the possibility of using HCM (composed of 45.2% of R290 and 54.8% of R600a) as R134a alternative at different ambient temperatures needs further investigation. The objective of the present study is to explore the possibility of using above mentioned HCM in a 150 l domestic refrigerator with different mass charges (40, 50, 60 and 70 g). The influence of ambient temperatures on the performance characteristics of the refrigerator under continuous and cycling running operating mode at different freezer air temperatures with 32 ?C ambient temperature have been studied.1,2,…12
1.7 Refrigerant Selection
In refrigeration and air conditioning systems selection of an appropriate working fluid is one of the most significant steps for a particular application. Low global warming potential has been inserted to the long list of desirable criteria of refrigerant’s selection. In fact, environmental characteristics of refrigerants are becoming the dominant criteria provided that their thermodynamic behaviors and safeties are favorable as well.

1. Environmental impact and safety aspects
2. Zero ODP and Low GWP Refrigerant
1.8 THEORETICAL AND RESEARCH STUDY OF ALTERNATIVE REFRIGERANTS TO R134a
Many investigators have reported that GWP of HFC refrigerants is more significant even though it has less than that of chlorofluorocarbons (CFC) refrigerants. HCFCs (hydro chlorofluorocarbons) and CFCs (chlorofluocarbons) have been applied extensively as refrigerants in air conditioning and refrigeration systems from 1930s as a result of their outstanding safety properties. However, due to harmful impact on ozone layer, by the year 1987 at Montreal Protocol it was decided to establish requirements that initiated the worldwide phase out of CFCs. By the year 1992, the Montreal Protocol was improved to found a schedule in order to phase out the HCFCs. Moreover in 1997 at Kyoto Protocol it was expressed that concentration of greenhouse gases in the atmosphere should be established in a level which is not intensifying global warming ozone layer. Subsequently it was decided to decrease global warming by reduction of greenhouse gases emissions.

1. Characteristics of R134a and new proposed refrigerants:
The properties of the refrigerants for wide range of temperatures (between ?60 and 60 °C) are compared in Figs. 1. Using Refprop 7 all properties can be evaluated and their comparison as shown in graphs. Fig. (a) depicts the variation of saturation pressure of R134a, R290, R600a, and blends of R290/R600a % by wt. (45.2/54.8 HCM 1, 50/50 HCM 2, 54/46 HCM 3, 56/44 HCM 4, 60/40 HCM 5 and 68/32 HCM 6) against temperature. It was observed that all of the HCM has approximately the same vapor pressure as R134a in the evaporator temperature ranging between -60 and 100C. Hence the compressors can operate relatively at lower pressures with HCM than R134a. R290 has higher vapor pressure than R134a hence the compressor operate at higher pressure and R600a has very low vapor pressure (below atmospheric pressure) than R134a, thus increasing the possibility of drawing contamination in to the system in the event of a leak so that R600a is less suitable for low temperature applications. Hence with pure HCs (R290 and R600a) HC type compressor is needed.

Fig.1.6: Effect of temperature on (a) saturation pressure and (b) liquid density 4
In Fig.1.5 (b) Depicts the variation of liquid densities against temperature. It was observed that the liquid densities of all of the HCM and Pure HCs (R290 and R600a) refrigerants were found to be lower than that of R134a, as the liquid density is low it will significantly reduce the refrigerant charge requirement. Thus we can expect that if we will proceed with R290, R600a, and HCM it requires less charging amount as compare to that of the R134a. The other properties such as critical temperature, critical pressure, boiling point, molecular weight, ODP and GWP of R134a, R290, R600a and all of the HCM are compared in Table.

Refrigerant Chemical
Composition N.B.P
°C Molecular
weight
g/mol Critical
Temp.

°C Critical
pressure
MPa GWP
R134a CH2FCF3 -26.15 102 101.1 4.059 1300
Propane(R290) CH3-CH2-CH3 -42.1 44.096 96.675 4.247 3
Isobutene (R600a) CH3-CH-CH3
CH3 -11.73 58.12 134.67 3.65 3
R290/R600a(HCM1) 45.2/54.8 -31.13 50.816 118.54 4.096 <20
R290/R600a(HCM2) 50/50 -32.47 50.147 116.74 4.126 <20
R290/R600a(HCM3) 54/46 -33.52 49.602 115.22 4.154 <20
R290/R600a(HCM4) 56/44 -34.01 49.334 114.45 4.165 <20
R290/R600a(HCM5) 60/40 -34.97 48.807 112.92 4.186 <20
R290/R600a(HCM6) 68/32 -36.72 47.786 109.8 4.22 <20
Table 1.1:Alternative low GWP refrigerants to R134a. 7
There are practical problems associated with the use of hydro fluorocarbon (HFC) refrigerants such as R134a:
HFCs are not miscible with the mineral oils commonly used today. Polyol ester oils must be used instead of mineral oils. These are more dangerous to handle (contact with skin can cause problems) and more readily absorb moisture from air.

The HFC and polyol ester oil mixture reacts in a different way, compared to R12 and mineral oils, with many seal materials. If these seals are not changed, leaks can occur.

Polyol ester oils are more expensive. Servicing is more difficult for HFC systems.

HFCs and polyol ester oils are not as tolerant to moisture and other contamination in systems, so failures are more likely to occur if systems are not thoroughly cleaned and dehydrated before changing.

It is not considered feasible to repair compressors after a burn out except in closely controlled conditions. This move away from HFCs has been further accelerated by concern caused by their potent global warming potentials. Some European countries have already decided to phase out HFCs because of this environmental problem.

2. Hydrocarbon refrigerants:
Hydrocarbons (HCs) are very good refrigerants for many reasons:
They are compatible with copper and the standard mineral oils;
They have a very low environmental impact in comparison with CFCs, HCFCs and HFCs;
They perform very well, with good capacity and efficiency;
Due to lower liquid densities, low refrigerant charge than that of HFCs;
High heat transfer coefficients hence high latent heat of vaporization;
Coefficient performance (COP) of the system increases and Power consumption reduced with HCs;
Improves compressor life due to low discharge temperature compare to HFCs, HCFCs and CFCs;
Service procedures can remain largely the same as for R12 and R22 refrigerants, except for safety considerations due to its flammability. However, HCs show relatively high flammability, but the flammability of the mixture of R290 and R600a is not a problem in a small- capacity refrigeration system with the refrigerant charge below 100g based on R134a. Very few changes are needed to a system and its components to be able to use HCs refrigerants. However, care is needed to ensure that flammability does not present safety problems:
Systems using HCs must be designed so that leakage is not dangerous.

During charging, appropriate equipment should be used to charge the systems, and the charging area has to be chosen with care.

Service technicians must be trained to handle HCs refrigerants safely.

1.9. OBJECTIVE OF PROJECT
The development of statistical models ,new hydrocarbon blends ,to investigate COP, GWP, ODP, EER of domestic refrigerator in different methods like that practical, theoretical, software.& Electric Power Consumption, Refrigeration Capacity, Compressor work and Coefficient of Performance (COP) by determining important parameters during in operating mode which are temperature, pressure with domestic refrigerator using Refrigerant R134a,R1234yf,Blends of R32,R600a,R290 at Constant Evaporator Temperature.

1 To find out Actual COP of Refrigerant blend at different mixing ratio
2 To investigate blends having zero ODP and GWP.

3 To become aware about how to calculate EER and to give energy star rating of domestic refrigerator
4 To find out best suitable Alternative Refrigerant to Replace R134a in Domestic Refrigerator without any modification in VCR system.

CHAPTER 2 LITERATURE REVIEW
In recent past, R134a, R12 was used as working substance in domestic refrigerator. But use of R12 was abandoned because of ozone layer depletion (ODP) problem. Or use of R12 was abandoned because of Global Warming Potential (GWP) problem now a day, R600a is used as working substance in domestic refrigerator. R600a (Hydrocarbon refrigerant) is used in domestic refrigeration and other vapor compression system.

Mani et.al. 1 experiments are conducted using R12, R134a and R290/R600 mixture refrigerants. In this work the following conclusions are made. A five level factorial experimentation technique is employed for developing statistical models and the performance of R12, R134a and R290/R600 (79/21 by wt %) mixture are compared. The refrigerating capacity of R290/R600 (79/21 by wt %) is 49% higher for lower Te temperatures and 30% higher for higher Te than that with R12 and R134a R290/R600 mixture consumed 21.3%-22.2% higher power than R12 and R134a at all the operating conditions due to the increased work of compression.

The COP of R290/R600 (79/21 by wt %) mixture is 19.3%-27.9% higher than that of R12 and the COP of R134a is close to that of R12 for the range of evaporating temperatures. Interaction effects of Te, Tcand N on RC, PC and COP for the refrigerants R12, R134a and R290/R600 are discussed using 3D plots. The investigated hydrocarbon mixture R290/R600 (79/21 by wt %) can be used as a possible alternative refrigerant for R12 and R134a
Joybari et.al. 2 studied first energy analysis was carried out for 145 g of R134a. Then, R134a was replaced by 60 g of R600a, compressor was changed to a HC type one and energy analysis was applied to the refrigerator to improve its performance. According to the results, R600a charge amount, compressor COP and condenser fan rotational velocity were selected for Taguchi design. It was found that at optimum condition the amount of charge required for R600a was 50 g which is 66% lower than R134a one; Besides, R134a is about two times more expensive than R600a which makes R600a use economically beneficial. Compressor modification is strongly recommended to enhance the system. Furthermore, the amount of total energy destruction in optimum condition (0.025 kW) is 45.05% of the base refrigerator one (0.05549 kW) which confirms the enhancement of the cycle for 54.95%. .

Exergy analysis of a refrigerator with 145 g of R134a showed that the compressor had the highest amount of exergy destruction followed by the condenser, capillary tube,
evaporator and superheating coil had the highest exergydestruction.Using Taguchi design, the optimum condition was found to be R600a charge amount of 50 g, compressor coefficient of performance of 1.82 and condenser fan rotational velocity of 1800. The amount of charge required for R600a is 50 g, 66% lower than R134a one.The amount of total exergy destruction in optimum condition is 45.05% of the base refrigerator one.

sheikh et.al. 3 studied Energy Efficiency Ratio of R-600a is higher than R-134a. Experiment carried out using refrigerant R134a and R600a at in Domestic Refrigerator; it is found that cooling Capacity using Refrigerant for constant refrigeration effect is 107.03. Whereas for same refrigeration effect the cooling Capacity using Refrigerant R600a is 142.10.Compressor energy consumption of domestic refrigerator decreased by 10-15% with using refrigerant R600a.

Exergy analysis of a refrigerator with 145 g of R134a showed that the compressor had the highest amount of exergy destruction followed by the condenser, capillary tube,
evaporator and superheating coil had the highest exergydestruction.Using Taguchi design, the optimum condition was found to be R600a charge amount of 50 g, compressor coefficient of performance of 1.82 and condenser fan rotational velocity of1800.The amount of charge required for R600a is 50 g, 66% lower than R134a one.

The amount of total exergy destruction in optimum condition is 45.05% of the base refrigerator one.

Mahajan.et.al. 4 studied the harmful refrigerants are to be phased out and are to be replaced with alternate environmental friendly refrigerants with zero ozone depletion potential (ODP) and negligible global warming potential (GWP), to replace R-12 and R134a in domestic refrigerator Hydrocarbons blends may replace R-134a without any system modifications. COP of the system is improved with reduced energy consumption. Hydrocarbon refrigerants are compatible with mineral oils (commonly used lubricants). Hydrocarbon technology provides a simple, sustainable and cost-effective solution for replacing R-134a in the domestic refrigeration subsector in developing countries.

Kumar et.al. 5 R600 has the highest value of EER among R134a, R152a, R290, R600 and R600a at 40°C but at 55°C R600a has the highest value of EDR among R134a, R152a, R290, R600 and R600a.R600a has the highest value of Efficiency defect in compressor among R134a, R152a, R290, R600 and R600a.R290 has the highest value of Efficiency defect in throttle valve among R134a, R152a, R290, R600 and R600a.R600 has the highest value of Efficiency defect in evaporator among R134a, R152a, R290, R600 and R600a.

This study presents a comparison of energy and exergy analysis for R134a, R152a, R290, R600 and R600ain refrigerator. The paper analyzes the domestic refrigerator with alternative refrigerants for computing coefficient of performance, exergy destruction ratio, exergy efficiency and efficiency defect. The method of exergy provides a measure to judge the magnitude of energy waste in relation to the energy supplied or transformed in the total plant and in the component being analyzed, a measure for the quality (or usefulness) of energy from the thermodynamic viewpoint and a variable to define rational efficiencies for energy systems. It is established that in the present work efficiency defect is maximum in condenser and lowest in evaporator. Comparison of various properties for alternative refrigerants has been done for a domestic refrigerator.

Jatav et. Al. 6 This review paper presents the work on the performance of condenser used in refrigeration system by the various researches. Micro channel condenser used to enhance the performance of various parameters like heat transfer, pressure drop, energy efficient ratio, COP and refrigerant effect of the system. In refrigeration system condenser is a vital part. Micro channel heat exchanger has been increasingly applied in HVAC&R (Heating, ventilation and air conditioning &refrigeration) field due to its higher efficiently heat transfer rate more compact structure.

The COP of the system has been improved with the hydrocarbon refrigerants. The average COP of HC 19% higher than that of R134a.The domestic refrigerator was charged with 60g in 134a and 40g of HC. This is indication of better performance of HC as refrigerants. Refrigeration efficiency of the system increases with the increases in condensing and evaporating temperature. Mass flow rate is reduced when we are using hydrocarbon as refrigerant.

Bhargav et.al. 7 He Studied that A domestic refrigerator designed to work with R134 a was investigated to assess the possibility of using a mixture of propane and iso butane. The performance of the refrigerator using azotropic mixture as refrigerant was
investigated and compared with the performance of refrigerator when R134a, R12, R22, R290, R600a is used as refrigerant. The effect of condenser temperature and evaporation temperature on COP, refrigerating effect, condenser duty, work of compression and Heat Rejection Ratio where investigated. The energy consumption and COP of hydrocarbons and there blends shows that hydrocarbons can be used as refrigerant in the domestic refrigerator The paper deals with the energy analysis of mixture and of propane and iso butane with R12 and R134a.The cycle considered for study is having super heatedvapour after compression. Efforts have been made to
consider super cooling also.comparison of mint gas is done with R-12 and R-134 for in domestic refrigerators. From the observation we found that mint gas can be an option which could produce better results. Al though its implementation requires a detail experimental calculations. Mint gas is providing more COP then ordinary refrigerants another advantage of this refrigerant was that it does not react with compressor oil. The only disadvantage associated with this gas is its flammability, which can be an obstacle in its implementation. This problem can be solved by proper design of the refrigerator.

Cabello et.al.8 studied the influence of the evaporating pressure, condensing pressure and superheating degree of the vapour on the exergetic performance of a refrigeration plant using three different working fluids R134a, R407c, R22.

In this paper, the influence of the main operating variables on the energetic characteristics of a vapour compression plant, based on experimental results, is addressed. The experimental tests are performed on a single-stage vapour compression plant using three different working fluids, R134a, R407C and R22.The operating variables considered are the evaporating pressure, the condensing pressure and the superheating degree at the compressor inlet. The performance characteristics followed to analyse the energetic performanceare the refrigerating capacity and the power requirements of the reciprocating compressor, presenting and discussing in this work the main experimental results obtained.

Kumar et. al. 9 studied the behavior of HCFC (Hydrochloroflurocarbon) -123/ HC-290 refrigerant mixture computationally as well as experimentally and found that refrigerant mixture 7/3 as a promising alternative to R12 system.

At the advent of the Montreal protocol, R134a has been suggested as an alternate refrigerant to R12. R134a is a high global warming potential gas and needs to be controlled as per the Kyoto protocol. It is reported that there is no single refrigerant or mixture available to satisfy both the ozone depletion potential (ODP) and global warming potential (GWP) issues. In this scenario, the objective of this work was, to develop an eco-friendly refrigerant mixture with negligible ODP and GWP values that is nearly equivalent to R12 in its performance. R123 is a potential refrigerant with very low ODP and GWP values, but due to its high suction specific volume and high boiling point, it has not been considered as an alternate refrigerant to R12. In this work, to overcome the above said problems, R290 has been identified as suitable for combination with R123 in a refrigerant mixture. Using REFPROP for analysis, it was found that the performance parameters for a mixture containing 70% R123 and 30% R290 were near matching with R12. This has been further confirmed experimentally by conducting a base line test with R12 and tests with the new mixture. The flow characteristics of the mixture were compared with R12 and presented.

Bolaji et.al. 10 investigated experimentally the performances of three ozone friendly Hydrofluorocarbon (HFC) refrigerants R12, R152a and R134a. R152a refrigerant found as a drop in replacement for R134a in vapour compression system.

In this paper, the performances of three ozone-friendly Hydrofluorocarbon (HFC) refrigerants (R32, R134a and R152a) in a vapour compression refrigeration system were investigated experimentally and compared. The results obtained showed that R32 yielded undesirable characteristics, such as high pressure and low Coefficient of Performance (COP). Comparison among the investigated refrigerants confirmed that R152a and R134a have approximately the same performance, but the best performance was obtained from the used of R152a in the system. As a result, R152a could be used as a drop-in replacement for R134a in vapour compression refrigeration system. The COP of R152a obtained was higher than those of R134a and R32 by 2.5% and 14.7% respectively. Also, R152a offers the best desirable environmental requirements; zero Ozone Depleting Potential (ODP) and very low Global Warming Potential (GWP)
Balakrishnan et.al.11 studied that,This paper explores an experimental investigation of an alternative eco-friendly refrigerant for R134a with a better Coefficient Of Performance (COP), reduced Global Warming Potential (GWP) and Ozone Depletion Potential(ODP). This investigation has been accessed using a hydrocarbon refrigerant mixture composing of R32/R600a/R290 in the ratio of 70:5:25 by weight. The performance characteristics of the domestic refrigerator were predicted using continuous running tests under different ambient temperatures and cyclic running (On/Off) tests at the fixed temperatures i.e., evaporation temperature (-5?C) and condensation temperature (30?C). The obtained results showed that the hydrocarbon mixture has lower values of energy consumption; pull down time and ON time ratio also higher Coefficient of Performance (COP). Thus, the performance of the alternate refrigerant derives the better choice than R134a.

Dalkilic et. al. 12 studied the A theoretical performance study on a traditional vapour-compression refrigeration system with refrigerant mixtures based on HFC134a, HFC152a, HFC32, HC290, HC1270, HC600, and HC600a was done for various ratios and their results are compared with CFC12, CFC22, and HFC134a as possible alternative replacements. In spite of the HC refrigerants’ highly flammable characteristics, they are used in many applications, with attention being paid to the safety of the leakage from the system, as other refrigerants in recent years are not related with any effect on the depletion of the ozone layer and increase in global warming. Theoretical results showed that all of the alternative refrigerants investigated in the analysis have a slightly lower performance coefficient (COP) than CFC12, CFC22, and HFC134a for the condensation temperature of 50 °C and evaporating temperatures ranging between ?30 °C and 10 °C. Refrigerant blends of HC290/HC600a (40/ 60 by wt.%) instead of CFC12 and HC290/HC1270 (20/80 by wt.%) instead of CFC22 are found to be replacement refrigerants among other alternatives in this paper as a result of the analysis. The effects of the main parameters of performance analysis such as refrigerant type, degree of subcooling, and superheating on the refrigerating effect, coefficient of performance and volumetric refrigeration capacity are also investigated for various evaporating temperatures.

performance analysis of alternative new refrigerant mixtures as substitute for R12, R134a and R 22. Refrigerant blend of R290/R 600a (40/60 by wt. %) and R 290/R1270 (20/80 by wt. %) are found to be the most suitable alternative among refrigerants tested for R12 and R22.

Wongwises et.al. 13 found that 6/4 mixture of R290 and R600 is the most appropriate refrigerant to replace HFC134a in a domestic refrigerator. This work presents an experimental study on the application of hydrocarbon mixtures to replace HFC- 134a in a domestic refrigerator. The hydrocarbons investigated are propane (R290), butane (R600) and is butane (R600a). A refrigerator designed to work with HFC-134a with a gross capacity of 239 l is used in the experiment. The consumed energy, compressor power and refrigerant temperature and pressure at theinlet and outlet of the compressor are recorded and analysed as well as the distributions of temperature at various positions in the refrigerator. The refrigerant mixtures used are divided into three groups: the mixture of three hydrocarbons, the mixture of two hydrocarbons and the mixture of two hydrocarbons andHFC-134a. The experiments are conducted with the refrigerants under the same no load condition at a surrounding temperature of 25 _C. The results show that propane/butane 60%/40% is the most appropriatealternative refrigerant to HFC-134a.

Reddy et.al. 14 studied the present review on the alternative refrigerants used in the domestic refrigerators to have better performance with minimum losses. This paper give the summary and range of various refrigerants used in the domestic refrigerators. of global warming which affect the environment by the use of refrigerant, and our aim is to reduce the effect of global warming as well as optimize the performance of domestic refrigerators by using the latest refrigerants. This review paper represents the recent developments done in domestic refrigerator. Performance of refrigerator is increased by using different refrigerants. R134a is used in domestic refrigeration and other vapor compression system. R134a is having zero ozone depletion potential (ODP) and almost good thermodynamic properties, but it has a high Global Warming Potential (GWP) of 1300.The higher GWP due to R134a emissions from domestic refrigerators leads to identifying a long term alternative to meet the requirements of system performance, Therefore it is going to be banned very soon for environmental safety. Some new refrigerants is been found by researchers which are environmental friendly refrigerants having low GWP and low ODP. Hydrocarbon refrigerants particularly propane, butane and isobutene are proposed as an environment friendly refrigerants. After reviewing the various literatures on the hydrocarbons (R290 and R600a) refrigerants and their mixture gives good performance in small capacity domestic refrigerator to replace R134a.Bhatkar et. al. 15 Vapour compression refrigeration is used in almost 80 % of the refrigeration industries in the world for refrigeration, heating, ventilating and air conditioning. The high-grade energy consumption of these devices is very high
and the working substance creates environmental problems due to environmental unfriendly refrigerants such as chloroflurocarbons, hydrochloroflurocarbons and hydroflurocarbons. Heating, ventilating, air conditioning and refrigeration industries are searching for ways to increase performance, durability of equipments and energy efficiency in a sustainable way while reducing the cost of manufacturing. With the present refrigerants, environmental problems such as ozone layer depletion, global warming potential, green house gases and carbon emission are increasing day by day. In this paper, the popular refrigerant is thoroughly studied experimentally and recommendations are given for alternatives such as carbon dioxide, ammonia and hydrocarbons and new artificially created fluid, Hydro- Fluoro-Olefin 1234yf by DuPont and Honeywell which exhibit good thermo-physical and environmental properties and will be commercialized in the near future.

Agrawal et.al. 16 worked on eco-friendly refrigerant as a substitute for CFC (Chloroflurocarbon). The binary mixture in the ration of 64% and 36% of R290 and R600a found to be a retrofit or drop in substitute of R12 for use in the vapour compression refrigeration trainer. He works on the study hydrocarbon refrigerants R600a and R290, in that he concludes that the bleds of R600a and R290 in mixture ratio of 64% and 36% is best suitable alternative to R134a.

Arora et.al. 17 had worked on a detailed analysis of an actual vapour compression refrigeration cycle. A computational model had been developed for computing coefficient of performance, exergy destruction, exergetic efficiency and efficiency defects for R502, R404A and R507A. The investigation had been done for evaporator and condenser temperatures in the range of -50°C to 0°C and 40°C to 55°C respectively. The results indicate that R507A was a better substitute to R502 than R404A. This paper presents a detailed exergy analysis of an actual vapour compression refrigerationb(VCR) cycle. A computational model has been developed for computing coefficient of performance (COP), exergy destruction, exergetic efficiency and efficiency defects for R502, R404A and R507A. The present investigation has been done for evaporator and condenser temperatures in the range of _50 _C to 0_C and 40 _C to 55_C, respectively. The results indicate that R507A is a better substitute to R502 than R404A. The efficiency defect in condenser is highest, and lowest in liquid vapour heat exchanger for the refrigerants considered.

Padilla et. al.18 found that R413A (mixture of 88% R134a, 9%R218, 3%R600a) can replace R12 and R134a in domestic refrigerator,study deals with an exergy analysis of the impact of direct replacement (retrofit) of R12 with the zeotropic mixture R413A on the performance of a domestic vapour-compression refrigeration system originally designed to work with R12. Parameters and factors affecting the performance of both refrigerants are evaluated using an exergy analysis. In the literature, no experimental data for exergy efficiencyare reported, so far, for R413A. Twelve tests (six for each refrigerant), are carried out in a controlled environment during the selected cooling process from evaporator outlet temperature from 15 _C to _10 _C. The evaporator and condenser air-flows are modified to simulate different evaporator cooling loads and condensers ventilation loads. The overall energy and exergy performance of the system working with R413A is consistently better than that of R12.

Tayde et.al. 19 design and investigated with classical refrigeration using vapour compression has been widely applied over the last decades to large scale industrial systems. Now, the mini-scale (miniature) refrigerator using VCR seems to be an alternative solution for the electronic cooling problem. Fabrication of very small devices is now possible due to advances in technology. In this investigation a mini-scale refrigerator of 300W cooling capacity using R-134a as refrigerant is designed, built and tested. This test indicates that the actual COP of the developed system is 1.6 and second law efficiency is 19%.

Ankitunde et.al. 20 In the vent of chlorofluorocarbons (CFCs) phase-out, identify long term alternative to meet requirements in respect of system performance and service is an important area of research in the refrigeration and are conditioning industry. This work focuses on experimental study of the performance of eco-friendly refrigerant mixtures. Mixtures of three existing refrigerants namely: R600a (n-butane), R134a (1,1, 1,2,tetrafluoroethane) and R406A (55%R22/4%R600a/41%R142b) were considered for this research. These refrigerants were mixed in various ratios, studied and compared with R-12 (dichlorodifluoromethane) which was used as the control for the experimentation. The rig used in the experimentation is a 2 hp (1.492 kW) domestic refrigerator, designed based on condensing and evaporating temperatures. The rig was tested with R-12, and blends of the three refrigerants. During the experimentation, both evaporator and condenser temperatures were measured. These were used to determine the heat absorbed in evaporator and the heat rejected incondenser. The results show that R134a/R600a mixture in the ratio 50:50 can be used as alternative to R-12 in domestic refrigerators, without the necessity of changing the compressor lubricating oil. At and , R-12 gives a COP of 2.08 while 50:50 blend of R134a/R600a gives a COP of 2.30 under the same operating conditions.

Sattar et.al. 21 studied the domestic refrigerator designed to work with R-134a was used as a test unit to assess the possibility of using hydrocarbons and their blends as refrigerants. Pure butane, isobutene and mixture of propane, butane and isobutene were used as refrigerants. The performance of the refrigerator using hydrocarbons as refrigerants was investigated and compared with the performance of refrigerator when R-134a was used as refrigerant. The effect of condenser temperature and evaporator temperature on COP, refrigerating effect, condenser duty, work of compression and heat rejection ratio were investigated. The energy consumption of the refrigerator during experiment with hydrocarbons and R-134a was measured. The results show that the compressor consumed 3% and 2% less energy than that of HFC-134a at 28 °C ambient temperature when iso-butane and butane was used as refrigerants respectively. The energy consumption and COP of hydrocarbons and their blends shows that hydrocarbon can be used as refrigerant in the domestic refrigerator. The COP and other result obtained in this experiment show a positive indication of using HC as refrigerants in domestic refrigerator.

Baskaran et.al. 22 determined the performance analysis on a vapour compression refrigeration system with various eco-friendly refrigerants of HFC152a, HFC32, HC290, HC1270, HC600a and RE170 were done and their results were compared with R134a as possible alternative replacement. The results showed that the alternative refrigerants investigated in the analysis RE170, R152a and R600a have a slightly higher performance coefficient (COP) than R134a for the condensation temperature of 50 C and evaporating temperatures ranging between -30 C and 10 C.

Refrigerant RE170 instead of R134a was found to be a replacement refrigerant among other alternatives. The effects of the main parameters of performance analysis such as refrigerant type, degree of sub cooling and super heating on the refrigerating effect, coefficient of performance and volumetric refrigeration capacity were also investigated for various evaporating temperatures.

Aasim et.al. 23 investigated experimental study of isobutene (R-600a), an environment friendly refrigerants with zero ozone depletion potential (ODP) and very low global warming potential (GWP), to replace R-134a in domestic refrigerators. A refrigerator designed to work with R-134a was tested, and its performance using R-600a was evaluated and compared its performance with R-134a. The average COP using R-600a was 27% higher than R-134a respectively. The power consumption by compressor reduced by 3.7% with R600a refrigerant. The compressor ON time ratio was lowered by 6.98% with R-600a compared with R- 134a. The experimental results showed that R-600a can be used as replacement for R-134a in domestic refrigerator.

Daviran et.al. 24 Studied that the automotive air conditioning system is simulated by considering HFO-1234yf (2,3,3,3- tetrafluoropropene) as the drop-in replacement of HFC-134a. The simulated air conditioning system consists of a multi-louvered fin and flat-plate type evaporator, a wobble-plate type compressor, a minichannel parallel-flow type condenser and a thermostatic expansion valve. The thermodynamic properties of the refrigerants are extracted from the REFPROP 8.0 software, and a computer program is simulated for the thermodynamic analysis. Two different conditions have been considered in this program for the cycle
analysis: for the first state, the cooling capacity is taken as constant, and for the second state the refrigerant mass flow rate is considered fixed. The performance characteristics of system including COP and cooling capacity have been studied with changing different parameters. The results show that the refrigerant-side overall heat transfer coefficient of HFO-1234yf is 18–21% lower than that of HFC-134a,
and the pressure drop is 24% and 20% smaller than HFC-134a during condensing and evaporating processes, respectively. Also, in a constant cooling capacity, the COP of HFO-1234yf is lower than HFC- 134a by 1.3–5%, and in the second case the COP of HFO-1234yf is about 18% higher than that of HFC-134a.

mohanraj et.al.25 studied that the energy performance of a domestic refrigerator has been assessed theoretically with R134a and R430a as alternative refrigerant. and he concludes that R430a has a low gwp of 109 as compare to R134a. In this work, the energy performance of a domestic refrigerator has been assessed theoretically with R134a andR430A as alternative refrigerant. The performance has been assessed for three different condensing temperatures, specifically, 40, 50 and 60 °C with a wide range of evaporator temperatures between ?30 and 0 °C. The
performance of the domestic refrigerator was compared in terms of volumetric cooling capacity, coefficient of performance, compressor power consumption and compressor discharge temperature. Total equivalent global warming impact of the refrigerator was assessed for a 15-year life time. The results showed that volumetric
cooling capacities of R430A and R134a are similar, so that R134a compressor can be used for R430A without modifications. The coefficient of performance of R430A was found to be higher than that of R134a by about 2.6–7.5% with 1–9% lower compressor power consumption at all operating temperatures. The compressor discharge temperature of R430A was observed to be 3–10 °C higher than that of R134a. Total equivalent global warming impact of R430Awas found to be lower than that of R134a by about 7% due to its higher energy efficiency. The results confirmed that R430A is an energy efficient and environment-friendly alternative to R134a in
domestic refrigerators.

Vaghela 26 is derived that R1234yf is best suitable is best suitable alternative refrigerant to R134a.he concludes that R1234yf has lower cop as compared to R134a;however it is best suitable refrigerant as drop in substitute because it has very low GWP and can be substituted in the existing automobile air conditioning system with minimum modification.

Rasti et.al.27studied that substitution of two hydrocarbon refrigerants instead of R134a in domestic refrigerator. experiments are designed on a refrigerator manufactured for 105 g R134a charge.the effect of parameters including refrigerant type, charge and compressor type are investigated. his research is conducted using R436a and R600a as a hydrocarbon refrigerant.This paper is devoted to feasibility study of substitution of two hydrocarbon refrigerants instead of R134a in a domestic refrigerator. Experiments are designed on a refrigerator manufactured for 105 g R134a charge. The effect of parameters including refrigerant type, refrigerant charge and compressor type are investigated. This research is conducted using R436A (mixture of 46% iso-butane and 54% propane) and R600a (pure iso-butane) as hydrocarbon refrigerants, HFC type compressor (designed for R134a) and HC type compressor (designed for R600a). The results show that for HFC type compressor, the optimum refrigerant charges are 60 g and 55 g for R436A and R600a, respectively. Moreover, for this type of compressor, the energy consumption of R436A and R600a at the optimum charges is reduced about 14% and 7%, respectively in comparison to R134a. On the other hand, when using HC type compressor, the optimum refrigerant charges for R436A and R600a are both 50 g, and the energy consumption of R436A and R600a at the optimum charges are reduced about 14.6% and 18.7%, respectively. Furthermore, when the refrigerator is equipped with HC type compressor, working under optimum charges of R436A and R600a have a total equivalent warming impact about 16% and 21% lower than base refrigerator, respectively. Totalexergy destruction of the domestic refrigerator with HFC type compressor for R134a, R600a and R436A are 0.0389, 0.0301, 0.0471, respectively and for R600a and R436A with HC type compressor are 0.0292, 0.0472, respectively.

2.1.Research Gap:
By studying the all above literature research ,They have done various experiments by using different refrigerant like R12,R290,R600a,R436a,R430a,pure and blends of hydrocarbons etc.by studying all these parameters I am going to study with different hydrocarbon blends of R32,R600a,R290.also by using R1234yf which is joint venture of Dupont and Honeywell in domestic refrigerator without any modification in VCR system.

CHAPTER 3 DESIGN AND DEVELOPMENT OF EXPERIMENTAL SYSTEM
3.1 Details of Experimental Setup
Table 3.1: Details of Experimental Setup
SI NO Description Dimension/Range
1 Refrigerator Capacity 170 litres2 Capillary Tube 0.031mm
3 Compound Gauge -30-220psi
4 Pressure guage0-250 psi
5 Vaccum Pump -30PSIG
6 R32/R600a/R290 76 gm
The R134a domestic refrigerator setup consist of a hermatically sealed compressor ,natural convection air cooled condenser having a cooling capacity level of 5.67KW/hr, an evaporator and copper capillary tube whose schematic diagram and photographic view of the experimental set up is given in the fig .Sensor is attached at the inlet and outlet of compressor, condenser and evaporator. Pressure gauge is attached at the compressor inlet and outlet. Compound gauge is fitted at the condenser outlet. Evacuation of moisture takes place with the help of service port service port. Vaccum pump is used for evacuation and through the charging system refrigerant was filled in the refrigeration system.
3.2 Compressor:
A refrigerant compressor, as name indicates, is a machine used to compress the vapor refrigerant coming out from an evaporator and to raise its pressure. It also continuously circulates the refrigerant through refrigeration system. Since the compression of refrigerant requires some energy input for performing its function, therefore a compressor must be driven by some prime movers.
There are three types of compressor which are common in used, they are
1. Reciprocating Compressor
a. Hermetically sealed.
b. Semi hermetically sealed.
c. Open type
2. Centrifugal compressor
3. Rotary compressor
The compressor used in this research work was hermetically sealed reciprocating type compressor. In which motor was enclosed along with the cylinder and crank case, inside the dome. The motor windings were cooled by incoming suction vapor. These have the advantages of no leakage, less noise and compactness.

Design of Compressor: 29
Volume flow rate through compressor V= QDV1/(h1-h4)
where, Design load QD = 0.46 Kw , h1= 412 KJ/Kg , h4 = 257 KJ/Kg
V = 0.00074 m3/sec
rpm of compressor N= 120cf / npwhere, frequency cf =50Hz, no. of poles = 2 , N=3000 rpm
Cylinder bore d = {( 240/?) QDV1 / nvaN (h1-h4)}1/3 14
nva = 1 – (vc/vs) (r1/1.4-1)
where, compression ratio r = P2/p1 = 13.33 , Taking vc/vs = 0.03
Nva = 83 %
Cylinder bore d = 6.1 mm
The length of stroke may be assumed 1 to 1.2 of bore
L = 7.32mm
Vs= V/nvTable 3.2: Compressor specifications:
Description Specification
Model K444 HAG
Capacity 0.46 KW
Suction Pressure 2.8 kg/cm2
Discharge pressure 13.8 kg/cm2
Bore 6.1 mm
3.3.Condenser :
Refrigerant from compressor passes through air cooled condenser. The function of condenser is to remove or reject heat of the hot vapor refrigerant discharged from the compressor to the atmosphere. The hot vapor refrigerant consists of heat observed by the evaporator and heat of compression added by the mechanical energy of the compressor motor. In air cooled condenser air is used as cooling medium. The axial fan is used in the setup so as to undergo forced convection in order to achieve more cooling by the condenser. 15
Condenser Design :The inner and outer diameter and length of the condenser tubes are as follows,
di=6mm d0=9.37mm L= 3.6m
Overall heat transfer coefficient U is given by,
1/U = A+(B/V0.8)
U=2.14 W/m2 0C
Q=UA?mThe log mean temp. difference?m= ?1-?2 /In (?1/?2)
Assume ambient air temperature as 300C, condenser inlet temperature as 1100C and condenser outlet temperature as 400C.
?m= 38.830C
Capacity of condenser is given by Q = m (h2-h4)
m=0.003kg/sec , h2=457KJ/kg , h4 = 257KJ/k
Q = 0.6 KJ/sec
A= Q/U ?mA= 0.009 m2
A=?.d0L.n
No of coils n =12 16 28

Table 3.3 : Condenser specifications
Description Specification
Material of Coil Copper
Diameter of Coil 9.37 mm
Length of Tube 3.6 m
No.of Rows 3
Nos01
Condenser Type Air cooled condenser
3.4 Capillary tube :-
Capillary tube is one of the most throttling devices in the refrigeration systems. The capillary tube is a copper tube of very small internal diameter. It is of very long length and it is coiled to several turns so that it will occupy less space. The internal diameter of the capillary tube used for the refrigeration.
Capillary tube design :- 28
The compressor work per unit mass is given by
w = (h2-h1) , w= 45KJ/kg
Compression capacity for 0.5 KW = mqc x 3600
= (0.5/w)xqcx3600= 6200 KJ/hr
Corresponding to 6200 KJ/h and 1.25mm capillary tube Length is found to be L=3m (capillary tube length Vs Compressor capacity graph) 17

Fig 3.1 Cappillary tube vs Compressor Capacity
3.5 Evaporator: 28
An evaporator is a device used to evaporate from liquid to gas while absorbing heat in the process. It can also be used to remove water or other liquid from mixtures.
Evaporator Design –
Inner diameter and length of coil
d0=7.81mm, L=9m
Q= m( h1-h4)
where, h1=412 KJ/Kg , h4=257 KJ/Kg
Q = 0.46 KW
Consider fluid enters evaporator at 270K ; leaves at 262 K, boilling temperature of refrigerant= 258 K
?m= ?1-?2 /In (?1/?2)
?m= 7.2 K
A = Q/ U?mWhere, U= 2.14 KJ/m2-m-s, A = 0.03 m2
A = ?d L n
No of tubes n =18

Table 3.4: Evaporator specifications
Description Specification
Material of coil Copper
Diameter of coil 7.81 mm
Length of tube 9 m
Nos02
3.6 Energy meter:
The energy meter is provided in the system that measures the power consumption by each and every component of the system such as the refrigerator, condenser fan, digital temperature indicator, etc.

3.7 Pressure gauges:
Two pressure gauges are mounted in the system to measure the pressures of suction and delivery sides. The suction gauge and delivery gauge a range from 0 to 250 psi.

3.8. Thermocouples:
The thermocouples are K type and have the range of -50 0c to 70 0c (108 0c Maximum measurable).

3.9 METHODOLOGY
The first step is to study the alternative refrigerant to replace R134a in a domestic refrigerator.

3.5 Properties of R32/R600a/R290 refrigerant given in the Table 4.2. 11
Table 3.5: Properties of R32/R600a/R290
Refrigerant R32 R600a R290
Safety level A1 A1 A1
Boiling point(oc) -52 -11 -41
Tcon(oc) 78.1 137.7 66
Pcond (bar) 5.78 3.78 3.62
COP 2.11 1.99 2.01
ODP 0 0 0
GWP 71.5 -20 -20
Methodology of this work is concentrated on two important things that need to be developed in order to investigate the performance of the domestic refrigerator which is location of measurement points and it devices, and experiment set-up.

3.9.1 Development of Location of Measurement Points
Refrigerator test rig was developed in order to investigate the performance of the system. In developing the reliable refrigerator test rig, consideration should be highly addressed especially the development method and measurement locations of pressure and temperature. They discussed the locations of temperature and pressure measurement points, measurement devices and measurement methods. As a result, a refrigerator test rig was developed. There are five points of temperature measurement, two points of pressure measurement and one is energy measurement. 8
From the five points of temperature measurement, four points have been placed inside the refrigeration circuit to measure refrigerant temperature and another one points have been placed in refrigerator compartments. The thermocouple wire was used to measure the temperature of refrigerant in the tube. The technique to measure the temperature where the thermocouple wire was put inside the refrigerant tube so that the measurement made was exactly the temperature of the refrigerant. However, the method to construct the sensor was different. Figure shows the method to construct the temperature measurement point in the refrigerant tube.8
By using this method, as shown in Figure was used to hold a thermocouple wire which was inserted into the tube and effectively sealed, as shown in Figure . The flared tube is fitted securely on to a copper J-junction which was then joined mechanically to the tube to reconnect every two consecutive components. The temperature of the refrigerant which now flowed through each J-junction was measured by the hot thermocouple junction or head, as shown in Figure . Prior to installation each thermocouple was calibrated using a platinum thermocouple against temperature of freezing point, room condition and boiling point of water.The thermocouple used was of J-type, 0.3 mm diameter and designed for temperature range between -50°C to 99°C. The accuracy is about ±2%.

Fig 3.2: Fabrication of Assembly method of Thermocouple
Besides that, two points of pressure were tapped respectively made on pipes connecting all main components. Bourdon Tube pressure gauges were used for each pressure measurement in this test rig (ANSI/ASHRAE Standard, 1989, ARI 1998). A tube with diameter 2.1 mm was used to connect the refrigerant tube to each pressure gauge as what was done by Philipp. Figure 4 shows the detail construction of the pressure measurement points. 8

Fig 3.3: Assembly method of pressure measurement using Bourdon type pressure

Fig 3.4: Fabrication of Assembly method of pressure measurement using Bourdon type pressure

CHAPTER 4 . EXPERIMENTAL SETUP
In short the experimental setup consists of following component: 3
1) Vapour compression refrigeration unit
Compressor
Condenser
Expansion device (capillary tube)
Evaporator
2) Energy meter
3) Five thermo-couple with digital display
4) Two pressure gauge
5) Main switch ; indicator

Fig 4.1: schematic dia1gram of a refrigeration system experimental setup system

a) Front view b) Back side view

c) Reading panel Front view d) Reading panel Back side view
Fig 4.2: Actual Experiment Set-up

4.1 Experimental procedure
Take known quantity of water in can.

Measure initial temperature of water and note down.

The can is place in freezer compartment.

The thermocouple no.5 dipped into water (water can)
Start the system by main switching on the compressor.

Start the stop watch.

Measure the initial suction and discharge pressure of compressor.

When ice is formed then stops the stop watch and measures all temperatures T1, T2, T3, T4, and T5.and measure the final suction and discharge pressure of compressor.

Use different formulas and get the calculated EER, COP in different methods.
4.2 PRECAUTIONS:
1) Maintain constant power supply to compressor.
2) Maintain the required pressure in the system.
3) Maintain the required level of water in the cane.
4) Do not open charging valve unless required for charging.
5) Do not open refrigerator door.

4.3 FORMULAE AND SAMPLE CALCULATION
4.3.1Energy Efficiency Ratio (EER): 3
Energy Efficiency Ratio is defined as the ratio of heat removed in B.Th.U.to Electrical Power Consumption in W.hr is known as the Energy Efficiency Ratio.

EER= Heat Removed in B.Th.U.Electric Power Consumption in W.hr 1
Where,
Heat removed in B.Th.U= R.E(KJ)1.055 = 462.321.055 =438.21
1B.Th.U=1.055 KJ
Hence, EER= 438.21400 =1.0955.

4.3.2.Coefficient of Performance (COP): 3
The coefficient of performance (COP) is expressed as COP or coefficient of performance which defined as Refrigeration Effect to Compressor Work.

a Actual COP
COP=Refrigerating Effect(R.E.)Cooling Effect(Win) 2
Where,
R.E. =M {Cpw(Tw-0) +L+Cpice (0-Tice)},KJ 3
M=Mass of Water
Cpw =Specific Heat of Water
Cpice = Specific Heat of Ice
L =Latent Heat
Tw =Initial Temp. of Water
Tice=Ice Temp.

R.E. =1{4.19(28-0) +335 +2(0-(-5))}
R.E.= 462.32 KJ.

Win =0.380×3600 =1368 KJ.

COP = =462.321368 =0.3379.

b Theoretical COP
COP=h1-h4h2-h1 4
Where, h1= After Evaporation Enthalpy
h2= After Compression Enthalpy
h3= After Condensation Enthalpy
h4= After Expansion Enthalpy
T1= After Evaporation Temp
T2= After Compression Temp
T3= After Condensation Temp
T4= After Expansion Temp
C EER (Based on COP)
EER=3.41×COP 5
= 3.41×0.3379 = 1.1522.

3 Energy Consumption Calculation
1. Normal Working Hour of a Refrigerator in a day = 6 Hr/Day
2. Actual working of Compressor “Cut In& Cut Out” Condition is 70 % =4.2 hr/day comp runs time.

4 Calculation of Energy Efficiency Ratio (EER) for Related Star Rating
EER=Energy ConsumptionkwhyearAdjusted Volume(Litre) 6
Where,
Adjusted volume =FFV+FZV×K×FcFFV = fresh food compartment volume
FZV = freezer compartment volume
K = adjustment factor
Fc = frost free factor
K=Room Test Temp.-Freezer Compartment Temp.Test Room Temp.-Fresh Food Compartment Temp = 34-(-15)34-(-10) 7
K =1.1136
Adjusted volume =170×1.1136×1.6 = 302.90.

Electric power consumption of 170 ltr = 0.750 unit/day
= 274 unit/ yr
Rate per unit =6.81 rsElectric power consumption per day =0.75×6.81= 5.1075 rs.

Electric power consumption per month = 5.1075×30 = 153 rsElectric poer consumption per year = 153×12 =1839 rs.

EER=274302.90= 0.9045.

Table 4.1: Relation between EER and Star Rating
Proposed Grading System (EER)
1 Star ? 1.45
2 Star 1.23 ? EER ? 1.44
3 Star 1.01 ? EER ? 1.22
4 Star 0.81? EER ? 1.00
5 Star EER? 0.80
EER of given refrigerator with Blend no.1 (mixing ratio:0/80/20) =0.9045.

Hence given refrigerator with mixing ratio of (0/80/20) is four star rated.

CHAPTER 5. RESULT ; DISCUSSION
Initial temperature of water Tw =280C
Temperature of ice (Tice)=-50C
Mass of water = 1 Kg
Specific heat of water(Cpw) = 4.19 KJ/KgK 28
Specific heat of ice (Cpice) = 2 KJ/Kgk 28
Latent heat (L) = 335 kJ/Kg
Table 5.1:- Experimental COP and EER of R32/R600a/R290
Blend No. Refrigerants Mixing ratio COP EER
1 R32/R600a/R290 0/80/20 0.3379 1.1531
2 R32/R600a/R290 10/70/20 0.3279 1.1236
3 R32/R600a/R290 20/60/20 0.3210 1.0955
4 R32/R600a/R290 30/50/20 0.3132 1.0688
5 R32/R600a/R290 40/40/20 0.2620 0.8943
6 R32/R600a/R290 50/30/20 0.2518 0.8592
7 R32/R600a/R290 60/20/20 0.2253 0.7687
8 R32/R600a/R290 70/10/20 0.2105 0.7183
9 R32/R600a/R290 80/0/20 0.1975 0.6741

Fig-5.1 COP oF various Rerigerant blends

Fig.5.2 EER of Various Refrigerant Blends

Fig 5.3 :- Variation in COP w.r.t. time
Fig 5.3 shows that the variation of COP with time at loading on condition. COP decreases with increase in time.

Fig 5.4 :- Variation in EER w.r.t. time
Fig 5.4 shows that the variation of EER with time at loading on condition. EER decreases with increase in time.

CHAPTER 6. CONCLUSION
The problem of R134a (GWP) is identified from the environmental site. Hence an alternative refrigerant is chosen with better COP and EER.

Mixing ratio (0:80:20) has higher value of COP Also mixing Ratio (20:60:20) has higher value of COP as compared with other blends and R134a,At loading condition ON.

The given Refrigerator with different Refrigerant blends is Four star rated.

Mixing refrigerant GWPAnd ODP is lower than R134a.
This refrigerant blends ( R32/R600a/R290) is comfortable as working substance in VCR system. Hence mixing Ratio (0:80:20),(10:70:20), (20:60:20),(30:50:20) Having higher value of COP hence This blends can Easily replace R134a in domestic Refrigerator.

FUTURE WORK
COP of the Other Refrigerant blends is Slightly lower than Refrigerant R134a because of R32 is lower Refrigerating Effect . Hence in Future use different Hydrocarbon Refrigerants Like R1234yf which is joint venture of Dupont and Honywell, also use different ecofriendly refrigerants with different mixing ratios.

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ANNEXURE

a) Front view b) Back side view

c) Reading panel Front view d) Reading panel Back side view
Fig Actual Experiment Set-up

Fig Fabrication of Assembly method of Thermocouple

Fig. Fabrication of Assembly method of pressure measurement using Bourdon type pressure