EXPERIMENTAL INVESTIGATION ON PERFORMANCE OF HOUSEHOLD REFRIGERATOR WITH DIFFERENT CAPILLARY TUBE LE

e-ISSN: 2582-5208 International Research Journal of Modernization in Engineering Technology and Science Volume:02/Issue:11/November -2020

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EXPERIMENTAL INVESTIGATION ON PERFORMANCE OF HOUSEHOLD REFRIGERATOR WITH DIFFERENT CAPILLARY TUBE LENGTH BY USING LOW GLOBAL WARMING POTENTIAL REFRIGERANTS Md. Jahangir Alam*1, D. C Vishwakarma*2 *1Mechanical *2

Engineering, All Saints’ College of Technology, Bhopal, India.

Mechanical Engineering, All Saints’ College of Technology, Bhopal, India.

ABSTRACT These impacts have lead the researchers and manufacturers to find suitable alternates such as Hydro fluorocarbons (HFCs) and Hydrocarbons (HCs), which have zero/low ozone depletion (ODP), low global warming potential (GWP) and are safe to the environment. A detailed experimentation was carried out in a vapour compression test rig to compare the performance and effectiveness of the system based on the following parameters: i) Evaporator Load (Qe), ii) Condenser Load (Qc), iii) Work done by Compressor (Wc), Refrigeration Effect (R.E), iv) Coefficient of Performance (COP) and v) Effectiveness ( ) of the system. The experimental results shows that R600a (Isobutane) a hydrocarbon performed better than R12 (CFC), and R152a (Difluoroethane) in terms of COP and energy consumption. The comparison between the four refrigerants selected for the study revealed that hydrocarbon refrigerant R600a (Isobutane) recorded the lowest temperature of -3.7 C in the chiller for the capillary length of 1.55m Moreover, the energy consumption by hydrocarbon R600a was 8% and 30% less for capillary lengths 1.25m and 1.55m. Based on their environmental benefits hydrocarbon refrigerant R600a is selected as a suitable ecofriendly alternate refrigerant which is cost effective, energy efficient and safe to the environment .

Keywords: Refrigerants

I.

INTRODUCTION

Refrigeration means the artificial withdrawal of heat, producing in a substance or within a space a temperature lower than that which would exist under the natural influence of the surroundings. Cooling effect created by a machine or mechanical device is classified as mechanical refrigeration. Since prehistoric times, artificial cooling has been recognized as desirable; food was kept in cold air in caves and wells 10 keep it fresh for longer periods.

Two physical phenomena were used in most remote times—without much understanding of the principles involved—evaporation of water, especially through vases of porous pottery (Figure 1.1) widely used in Egypt.

India and China, and terrestrial radiation towards clear sky during the night. It is known that several centuries before the birth of Christ. Egyptians made ice by this means by putting porous earthen pots on the roof of the house during the night. Evaporation of water in cool dry air together with radioactive heat transfer during a clear night caused ice formation even when the ambient temperature was above the freezing temperature.

Fig. 1.1 Earthen containers used by Egyptians for cooling water and making ice.

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The first refrigerator used for commercial and domestic purpose was ―Electric Monitor Top Refrigerator‖ in 1927. In this refrigerator, the compressor and its assembly were placed above the cabinet and surrounded by a ring and sulfur dioxide was used as refrigerants which was highly flammable, toxic and irritative.

II.

REFRIGERANTS PRIOR TO THE DEVELOPMENT OF CFC’S

Water is one of the earliest substances to be used as a refrigerant, albeit not in a closed system. Production of cold by evaporation of water dates back to 3000 B.C. Archaeological findings show pictures of Egyptian slaves waving fans in front of earthenware jars to accelerate the evaporation of water from the porous surfaces of the pots, thereby producing cold water. Of course, the use of ―punkahs‖ for body cooling in hot summer is very well known in countries like India. Production of ice by nocturnal cooling is also well known. People also had some knowledge of producing sub-zero temperatures by the use of ―refrigerant mixtures‖. It is believed that as early as 4th Century AD people in India were using mixtures of salts (sodium nitrate, sodium chloride etc) and water to produce temperatures as low as –20o C. However, these natural refrigeration systems working with water have many limitations and hence were confined to a small number of applications. Water was the first refrigerant to be used in a continuous refrigeration system by William Cullen (1710-1790) in 1755. William Cullen is also the first man to have scientifically observed the production of low temperatures by evaporation of ethyl ether in 1748. Oliver Evans (1755-1819) proposed the use of a volatile fluid in a closed cycle to produce ice from water. He described a practical system that uses ethyl ether as the refrigerant. As already mentioned the credit for building the first vapour compression refrigeration system goes to Jakob Perkins (1766-1849).

Perkins used sulphuric (ethyl) ether obtained from India rubber as refrigerant. Early commercial refrigerating machines developed by James Harrison (1816-1893) also used ethyl ether as refrigerant. Alexander Twining (1801-1884) also developed refrigerating machines using ethyl ether. After these developments, ethyl ether was used as refrigerant for several years for ice making, in breweries etc. Early commercial refrigerating machines developed by James Harrison (1816-1893) also used ethyl ether as refrigerant. Ether machines were gradually replaced by ammonia and carbon dioxide based machines, even though they were used for a longer time in tropical countries such as India. Ethyl ether appeared to be a good refrigerant in the beginning, as it was easier to handle it since it exists as a liquid at ordinary temperatures and atmospheric pressure.

Fig. 2.1: Classification of refrigerants

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III.

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RESEARCH OBJECTIVE

The objective of the research work is to study and identify suitable conditions of vapor compression refrigeration system using two different refrigerants based on their ecofriendly nature such as R152a (isobutene) Hydro-fluorocarbon (HFC) refrigerants and R600a (Isobutene) (HC) with two different lengths of capillary tubes with lengths of 1.25m, 1.55m. Simulation of vapour compression experimental set up would be done using Artificial Neural Network (ANN) to validate the experimental data in terms of coefficient of performance and effectiveness of the system and to identify the suitable length of the capillary that gives the maximum efficiency to the system.

IV.

EXPERIMENTAL SETUP

The experimental set up consist of a reciprocating compressor, an air cooled condenser, an expansion device usually a capillary device and coiled evaporator surrounding the vessel for cooling of liquids. The actual view and the line diagram of the vapour compression refrigeration system are shown in Fig. 1.3 (i) and 1.4. The actual view of the chiller unit filled with water with a sensor to measure the temperature of water at noted intervals is shown in Fig. 1.3 (ii).

Fig. 4.1 (i) Actual view of the experimental setup of vapour compression refrigeration system

Fig. 4.2 (ii) Actual view of the chiller with temperature measuring probe

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V.

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WORKING PROCEDURE OF THE EXPERIMENTAL SET-UP

The vapour compression system is initially cleaned by nitriding the entire system and the evacuation of moisture is carried out with the help of a vacuum pump for nearly 30 mins and then the refrigerant is charged with the help of the charging system. The system was initially charged with the refrigerant R134 .Initially the system is switched on and allowed to run for 30 minutes in order to stabilize the flow of refrigerant into various components of the refrigeration system.

The readings recorded from the experimental set up at time interval of 10 minutes are the suction pressure of the compressor (P1), discharge pressure of the compressor (P2), suction temperature (T1), discharge temperatures (T2), condenser outlet temperature (T3) and evaporator inlet temperature (T4). A data sheet was created which included the readings obtained from the various locations of the experimental setup and calculations were performed. The plots obtained were compared to determine the most efficient and suitable length of capillary.

Fig. 5.1 Schematic diagram showing capillary length 1.25m, 1.55m

VI.

RESULTS AND DISCUSSION

 EFFECT OF TIME VERSUS WATER TEMPERATURE The parameters time and temperature are dependent on each other. The temperature of water gradually decreases with respect to time. The graphs plotted from Fig. 1.5 to 1.7 refer to time versus water temperature for the four refrigerants and various capillaries used in the study. Fig. 1.5 shows the comparison of time for different capillary lengths. The graph clearly indicates that the capillary length 1.55m has recorded a minimum temperature of 2.50C and the lengths 1.25m shows very less difference in temperature with the initial temperature of water.

Fig 6.1 In this diagram shows the variation between water temperatures versus time, here two different capillary length tubes used for experiment, in this figure 1.25mcapillary tube gives minimum water temperature than 1.55m capillary tube for R134a refrigerant.

Fig 6.2 In this diagram shows the variation between water temperatures versus time, here two different capillary length tubes used for experiment, in this figure 1.25mcapillary tube gives minimum water temperature than 1.55m capillary tube for R152a refrigerant.

Fig 6.3 In this diagram shows the variation between water temperatures versus time, here two different capillary length tubes used for experiment, in this figure 1.255m capillary tube gives minimum water temperature than 1.25m capillary tube for R600a refrigerant

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Fig. 6.1 Time versus water temperature for refrigerant R134a

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Fig. 6.2 Time versus water temperature for refrigerant R152a

Fig. 6.3 Time versus water temperature for refrigerant R600a

VII.

EFFECT OF TIME VERSUS WORK OF COMPRESSION

The work of compression is dependent on the discharge pressure and temperature. Fig 1.8 to 1.10 shows the graphs plotted with the experimental data for time versus work of compression for the refrigerants selected for the study. The results shows progressive increase in the work of compression as time increases, which will be an influencing factor for the increase or decrease in the evaporator temperature. It is clear from the above graphs, that the increase of capillary length increases the load on the compressor which in turn decreases the evaporator temperature. The result shows that the length 1.25m required more of compression work than for lengths 1.55m, irrespective of the refrigerants used for the analysis.

Fig 7.1 In this diagram shows the variation between works of compression versus time, here two different capillary length tubes used for experiment, here 1.55m length tube have more compression work than 1.25mcapillary tube for R134a refrigerant.

Fig 7.2 In this diagram shows the variation between works of compression versus time, here two different capillary length tubes used for experiment, here 1.25m length tube have more compression work than 1.55mcapillary tube for R152a refrigerant.

Fig 7.3 In this diagram shows the variation between works of compression versus time, here two different capillary length tubes used for experiment, here 1.25mlength tube have more compression work than 1.55m capillary tube for R600a refrigerant.

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Fig. 7.1 Time versus work of compression for refrigerant R134a

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Fig. 7.2 Time versus work of compression for refrigerant R152a

Fig. 7.3 Time versus work of compression for refrigerant R600a

VIII.  

Water temperature found minimum in case of 1.55m length capillary tube for all refrigerants and in case of R600a found minimum 20C at 250 min. of time.

Work of compression found minimum in case of 1.55m length capillary tube for all refrigerants and in case of R600a found minimum 49 W at 50 min. of time and found maximum in 250 min for all refrigerants.

IX. [1]

[2]

[3] [4] [5]

CONCLUSION

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