refrigerator charging unit

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RefrigeratorCharging Unit

1. INTRODUCTION

Refrigeration: refrigeration is defined as any process of heat

removal. More specially, refrigeration is defined as the branch of science that

deals with the process of reducing and maintaining the temperature of a space of

material below the temperature of the surroundings.

Multipurpose charging set is a single arrangement for charging the

education and air conditioning unit. This charging set is different than the other

method. This is a portable device which can be transferred from One place to

another its construction is simple and decorative one. This set is multipurpose

device; with charging the unit it can also achieve the vacuum in unit. The weight

of gas and pressure of gas going to the unit is directly measured at the time of

charging on this set so it is very useful device for charging the refrigeration and

air condition unit in laboratories.

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2. PRINCIPLE OF PROJECT

Evacuation : -

Removing of fully air present in the refrigeration unit is known as

evacuation.

The main purpose of evacuation process is that for charging the

refrigeration unit. The air should not be present in it. If evacuation is not carried

out some amount of air is present in the refrigeration unit carried out properly.

The leakage problems are rising in it.

Definition of Charging: -

Charging is the process of filling the gas in the refrigeration and air

conditioning system.

Principle of charging set: -

This is a new method used for the charging of refrigeration unit

differ than the other method.

The principle of this charging set is that whenever a charging is

carried out by this set how many amount of gas is supply to the refrigeration or

air conditioning unit is calculated with the help of spring balance and also

determine the pressure of the gas flowing through the charging line with the help

of compound pressure gauge.

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3. PART LIST

Sr. no. Part Quantity Material

1 3 way valve 2 Bronze

2 2 way valve 1 Bronze

3 Charging line 3 Rubber

4Compound

pressure gauge

1 -

5 Spring balance 1 -6 Refrigerant gas 1 kg R-12

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4. REFRIGERANT

The substance, which carries the heat from low temperature region

and discharge, the same to the higher temperature region is known as refrigerant.

Refrigerant removes the heat in the form of sensible heat as in case of air

refrigeration or in the form of latent heat as in the case of vapour refrigeration.

The refrigerants, which carry the heat in the form of latent heat and

also dissipate in the form of latent heat, are more efficient than the refrigerant,

which carry the heat in the form of sensible heat.

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RefrigeratorCharging UnitREFREGERANT IN COMMON USE.

1. Ammonia (NH3) :

Ammonia is one of the oldest refrigerant uses in refrigeration

system. Its excellence thermal property make it an idea refrigerant for ice plant,

cold storage etc. Ammonia has the highest refrigerating effect per unit refrigerant

capacity. It is much less expensive compare with any other refrigerant. Any

moisture, which may enter the system, will be dissolved in ammonia and it

attacks many foods, therefore it is not used for domestic refrigerant or where

there is danger of exposing foods to leaking ammonia. It attack non-ferrous

metal, brass and bronze, but it is non-corrosive to iron and steel. It is widely used

in vapour absorption refrigerant system as it soluble in water and easily expelled

when heated.

2. Freon 12 or Discholorodifluro methane ( CCL2F2) :

It is commercially term as F-12 or R-12. It is used for domestic

refrigerator. It is colorless odorless and non-toxic. Therefore it is best suitable for

domestic refrigerator. It is used with all types of condenser, air-cooled and water-

cooled. The boiling point is 29.8

0

c at atmospheric pressure make it suitable for

high, medium and low temperature application with any types of compressor. It

is soluble in oil; therefore, it is simplifies the problem of lubrication. But its

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RefrigeratorCharging Unitdisadvantage is that it is costly and leak cannot be detected easily. Its leak

detected with the halides torch.

3. Freon -22 Difluromonochloro Methane (CHCIF2) :

It has a boiling Point -40"C at atmospheric pressure. It is used for

low temperature production. It is also used in packaged air conditioners, where,

because of space limitations, Relatively small compressor displacement required

with R-22 water-cooled Condensers are used. When air-cooled condenser is used

with R-22 is not used. The main advantage of R-22 over R-12 is the smaller

compressor displacement required for same capacity.

4. Carbon dioxide (CO2) :

It is the oldest refrigerant used. Carbon dioxide is Odorless, non-

toxic, non-flammable, non-explosive and non-corrosive Refrigerant. It used in

hospitals, theaters, hotels and marine service where safety Is prime

consideration? Now days its use is limited for production of dry ice. But the

power required for 002 refrigerants is high.

5. Sulphur dioxide (S02):

In olden days it was used in domestic Refrigerator. It is now replaced

by freon-12. It is colorless and suffocating fluid. In presence of water it forms

sulphurous acid, it has low refrigerating effect Compared with other refrigerant and it is

heavy irritating and high toxic in nature.

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RefrigeratorCharging UnitPROPERTY OF IDEAL REFREGERANT

Therefore, ideal refrigerant should have following properties

(i) The boiling point should be low.

(ii) The condensing pressure should not be more.

(iii) Critical temperature should be high.

(iv) The latent heat of vaporization should be high.

(v) Specific heat of liquid should be low.

(vi) It should not have corrosive action.

(vii) It should not be flammable and explosive.

(viii) It should be non-toxic.

(ix) It should be easily detectable for leaks.

(x) It should have satisfactory heat transfer coefficient.

: Should be easily available at low cost.

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5. CONSTRUCTION

This is a simple arrangement for charging the refrigeration and air

conditioning unit. The main feature of this charging set is that the whole assembly is

carried on a rectangular base. This is portable device, which can be transferred from

one place to another its construction is simple land decorative one. A vacuum pump is

fitted on the base plate. In front vacuum pump a vertical rectangular angle set is

attached on which spring balanced is attached and the plywood and valve are attached

with the help of nut-bolt.

A vacuum pump is mounted for creating the vacuum in the unit.

An arrangement of spring balance is to be made for calculating how many

amount of gas is filled in unit. For calculating the amounting of the gas

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RefrigeratorCharging UnitRefrigerant the refrigerant cylinder is attached tom hook of spring balance with

the help of into cylinder hanger arrangement.

On the front side of this charging set a panel board is fixed for

mounting 2 three way valves and compound pressure gauge. Three charging

lines are required for this set. One charging line is joined between the vacuum to

connector disconnect the vacuum pump. The second charging line is connected

between the cylinder and valve V1 and end of valve V2, which is always open.

The third charging line is connected between the refrigeration unit

and common end of valve V2 for the purpose of connect or disconnect the unit

whenever required. One end of valve V2 is connected to the compound pressure

gauge with the help of flare nut. These two 3-way valve V1 and V2 are

connected with the help of copper tube and flare nut.

So this is a simple arrangement of charging set.

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6. WORKING

After assembling it is required to charge the system with refrigerant

gas. Many time charging is necessary after repair and maintenance of the

system.

Before charging the system evacuation of system is done. With the

help of vacuum pump air in the system is removed and vacuum is achieved. For

this purpose the vacuum pump is joined to the common end of valve V1 and

connection between cylinder and valve is turned off from cylinder it self. Then

turn the valve V2 on for the purpose of removing oxygen and nitrogen from the

unit. The vacuum created in the system should be below 300 mm of Hg.



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After vaccumisation of the system, the vacuum pump is disconnect

immediately with the help of valve V1 by turning it at off position. In this way at

the vacuum side connection is off and remaining two connections is on state.

The hand shut-off valve is used during change of line.

Before charging the system, calculate the amount of gas required

for the system. Then place the refrigerate cylinder with the help of cylinder

hanger arrangement on the spring balance to refrigerant into evacuated system to

exact quantity required. The purging should be done before admitting the gas

into system.

What amount of pressure present in the system is indicated by

compound pressure gauge. The amount of pressure is required inside the system

is controlled by valve V2.

After completing the process, pinch the process tubes and seal it.



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7. ADVANTAGES AND APPLICATION

Advantages: -

The weight of gas and pressure of gas going to the unit is directly

measured at the time of charging.

It is multipurpose device.

The connection of vacuum pump to the unit is directly connected with the

help of valve and charging line. So separate arrangement is not required

for achieving the vacuum in unit.

Simple in construction.

It is portable device, which can be transferred from one place to another.

Less maintenance.

Time is saved due to whole accessories are mounted on one table.

The initial and working cost is less.

Application: -

In refrigeration and air-conditioning industries.

In refrigeration shops and laboratories.

It is used for charging of ice plant domestic refrigerator etc.



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8. HINTS BEFORE CHARGING

Use clean & moisture free drums for transfer & charging purpose.

The system should be evacuated particularly when it is new.

The charging lines must be purged & it must be made sure that all

connections are tight air is not drawn in the system with the

refrigerant.

The suction pressure may not be allowed to rise above 2 Kg.sq.cm.

when charging. The pressure may be controlled with the cylinder

valve.

The refrigerant in the liquid from should under no circumstances to

the compressor.

The charging lines should not be flexible.

The head pressure must be watched for indications of over charge.



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9. TESTING OF CHARGING SET

(LEAK DETECTION)

Before charging the refrigeration unit, the whole system must be

tested for the purpose of arising leakage problem. If it is not done, the leakage

problem is created & the charging is not done properly i.e. evacuation is not done

properly.

For this test a high-pressure compressed air is drawn through a

charging set. Before entry of the high-pressure compressed air, a soap bubble are

placed on v/v port, connection of charging lines & copper tubes & compound

pressure gauge for the purpose of to detect the leakage. Then a compressed air is

pass through the system if leakage is find, tight the connection with Teflon tape

properly. This process is carried out up to the leakage problem is minimized.

Then the system is ready form charging.

Method Commonly Used For Leak Detection are: -

1) Bubble Method

2) Halide Torch Method

3) Electronic Leak Detector

4) Special Method for detection of Ammonia and Sulphur dioxide.



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RefrigeratorCharging Unit1) Bubble Method: -

This method of leak detection is the oldest one and is Universally

used with all the refrigerants. A solution of soap or some other leather forming

liquid detergent is applied with the brush over the subjected area or joint. The

leaking gas forms bubble, which can be easily been seen. This method of leak

detection can only be used when the system has positive pressure. If there is

vacuum present in the system, it will pull in the moisture or stop bubble, which

will be quite harmful.

2) Halide Torch Method: -

A carbon element is heated by methyl alcohol or hydrocarbon

flame in the halide torch. A rubber tube attached to the refrigerator. A

refrigerant going on the tube combines with the Flame to cause Perceptible

change in the Flame Color.

This method of leak detection is slow and insensitive and in

brightly lighted area it is almost impossible to locate small leaks.

3) Electronic Leak Detector: -

An electronic leak detector is more sensitive and faster responding.

The electronic detector contains an internal pump, which draws,

and air leaking gas through a probe and hose as the probe is passed over leaking



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RefrigeratorCharging Unit joints. A leak-detecting lamp Flashes at this moment. By adjusting a knob on

the Electronic detector the magnitude of the leak can also be found.

4) Special Method For detection of Ammonia and Sulphur dioxide: -

Ammonia leak can be detected by bringing a burning candle of

sulphur near the suspected spot. The candle will give a cloud of white smoke if

ammonia vapour is present there A solution of hydrochloric acid brought in the

Vicinity of ammonia leak will also give white smoke. The moistened strip of

Phenol Phalein Paper turns Pink when faintest trace of ammonia vapour comes in

contact with it.

Presence of sulphur dioxide can be detected by bringing aqueous

ammonia near the suspected area. It will give white smoke in the presence of

Sulphur dioxide. When no ammonia is available leak may located by the soap

bubble or oil test.



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10. METHODS OF CHARGING

By using this set the methods of charging are as follows:

There are three methods of charging as given below:

1. Charging thought the suction valve: -

A small installation, which needs to few kilograms of refrigerant, is

usually charged through the suction service valve gauge port. For this method of

charging the system is fully evacuated and charged a follows.

Charging line is connected to the suction valve gauge port. Attach a

gauge to the discharge valve and open half turn.

The other end of the charging lines us connected to a refrigerant cylinder,

which should be standing up right.

The cylinder valve is opened slightly and to flare nut is loosened at the

compressor end.



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RefrigeratorCharging Unit This operation removes air from the line, when the sound of escaping gas

is heard, the nut is tightened.

Suction valve is turned into close the suction line, thus drawing the gas

directly from the cylinder by the compressor.

Compressor is started drawing the requisite quantity of refrigerant. The

suction pressure should not be allowed to exceed 2 kg/sq.cm. Gauge.

The cylinder valve is closed and the compressor is allowed to run

sufficient time to reduce the pressure in charging time to 0 kg/sq.cm.

Gauge.

Compressor is stopped and the suction valve is back seated. The charging

line is detached and compound gauge attached. The valve is turned in one

half turn. The system is thus ready for testing and normal operation.

The refrigerant quantity to be charge is often weighted. In that case

the cylinder may be on the weighing platform, or suspended from spring scale.

The tubing should be coiled and long enough to get true weight. The cylinder

may be kept in warm water to quacked the process of charging.

2. Charging through discharge valve: -

The method is used for certain conditions where it is impossible or impracticable

to add refrigerant by the other methods. This is the least used to the three



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RefrigeratorCharging Unitmethods. The refrigerant is caused to flow by difference in pressure between

cylinder and high side. The compressor is not operated while the unit is being



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RefrigeratorCharging UnitCharged. In order to save time when charging by this method, it is imperative to

weight into an empty cylinder the exact amount of charge required by the system.

If this is known, all contents of cylinder transferred. The system is evacuated

and following procedure adopted.

The discharge and suction service value are back-seated. The gauge port

of each valve is plugged or otherwise kept closed until the valves are wide

open.

Compound gauge is attached to the suction valve and the valve is turned

in one-half turn. A pipe-to-flare adapter is installed to the discharge valve

port and the charging line is connected to the adapter.

The other end of the charging line is connected to the cylinder. The air is

removed from line by loosing flare nut. The nut is tightened. The valve A

is turned in about half way.

The cylinder is placed bottom side up since the refrigerant will flow into

the condenser in liquid form.

After the refrigerant has flowed into the condenser, the discharge valve is

back-seated cylinder valve is closed and the charging line is removed.

The pressure gauge is attached and the valve is ready for testing and

operation.



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The cylinder valve is opened slightly and the flare nut is loosened

at the charging valve to purge the air from the line. When the

sound of escaping gas is he hard the nut is lightened.

The cylinder is tipped to ensure liquid at the valve and then

charging and cylinder valves are opened wide.

Compressor is started and the system is charged with required

quinsy. When cylinder becomes empty, frost will form on the

bottom of the cylinder and the charging line.

After completing the charging close the cylinder valve and run the

compressor for sometime to empty the charging line. Then close

the charging valve C, and remove the line. The charging valve is

capped to prevent leakage.

The receiver valve R is opened, the system is ready for testing and

operation.

When charging refrigerant into an ammonia plant using the above

method. It is necessary to lay the cylinders have an internal

gooseneck which makes this necessary. Charging connections for

ammonia should be made rigid steel pipe and fittings. For other

refrigerants use copper tubing Flexible connections, in the authors

opinion are dangerous.



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11. CONCLUSION AND MODIFICATION

Conclusion: -

In the end we concluded that by using this instrument we could

evacuate and charge the refrigeration and air conditioning system

simultaneously. This means that we can save a time by connecting and

disconnecting of the charging line. It is used in the charging of refrigeration and

air conditioning system in an industries, laboratories etc.

Modification: -

1. It is possible to weight a refrigerant, which is supplied to the system.

2. From the system we can evacuate and charged the refrigeration and air

conditioning system fastly.



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12. COST ANALYSIS

Sr. no. Name of material Material Quantity Cost

1. 3- way valve Bronze 2 360

2. 2-way valve Bronze 1 180

3. Copper tube with flare nut Copper 2 80

4. Compound pressure gauge with

adaptor

-- 1 205

5. Charging line Rubber 3 380

6. Cylinder with gas R-12 1 kg 690

7 Angle C.I. 12 kg 210

8 Vacuum pump -- 1 no. 22009. Spring balance -- 1 no 90

10. Plywood Plywood 10 sq. ft. 100

11. Screw C.I. 34 nos. 15

12 Roller Rubber 4 nos. 80

13. Welding -- -- 200

14. Color -- -- 120

15 Other -- -- 725

Total Rs.

5635

BIBLIOGRAPHY

1. Refrigeration and air conditioning

S.C Arora , S. Domculwar

2. Refrigeration and air conditioning system.

S.L. Gavhale

3. Refrigeration and air conditioning system.

S.T. Ghan, R.M. Naphade.



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refrigerator charging unit

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