METHOD FOR RECOVERING REFRIGERANT FROM A REFRIGERATION EQUIPMENT

Abstract

A method for recovering refrigerant from an external refrigeration equipment by a refrigerant recovery device includes recovering the refrigerant from the refrigeration equipment in a main recovering process. A small amount of heated refrigerant is recharged into the refrigeration equipment in a temporary refrigerant recharge process. An additional recovering process for emptying of a residual refrigerant from the refrigeration equipment is performed after finishing the temporary refrigerant recharge process.

Description

This invention relates to a method for recovering refrigerant of an external refrigeration equipment.

STATE OF THE ART

U.S. Pat. No. 5,720,184 discloses a low pressure refrigerant recovery recycle machine. The machine comprises a compressor and a refrigerant pump. The refrigerant pump connected to the refrigeration unit to recover the refrigerant and the compressor compresses the refrigerant that is recovered by the refrigerant pump.

ADVANTAGES OF THE INVENTION

The method of refrigerant recovery according to the independent claims have the following advantages.

The method of recovering refrigerant from a refrigeration equipment introduces a small amount of the high temperature high pressure refrigerant into the refrigeration equipment. This increases the temperature and pressure inside the refrigeration equipment. This also changes the state of the refrigerant inside the refrigeration equipment. This allows the compressor to recover additional refrigerant from the refrigeration equipment. Thus lesser amount of refrigerant is released into the atmosphere. This would reduce the pollutant released into the atmosphere, thereby reducing pollution considerably. This increases the working efficiency of the refrigerant recovery device.

Further improvements and/or advantages are realised by the features of the dependent patent claims.

Due to increase in temperature and pressure inside the refrigeration equipment the pressure equalization while the refrigerant is recovered will be slower. Hence additional refrigerant can be recovered. This increases the ability of the refrigerant recovery device to recover refrigerant.

The change in state of the refrigerant in the refrigeration equipment enables easier recovery of the refrigerant. The compressor has to be switched on for a shorter period for recovering the same amount of refrigerant. This reduces the power consumption. This in turn reduces the operating cost of the using the refrigerant recovery device.

When residual refrigerant is recovered from the refrigeration equipment, the amount of refrigerant released into the atmosphere is reduced considerably. This helps to reduce pollution.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

FIG. 1 illustrates a refrigerant recovery comprising various components and connection between the various components.

FIG. 1 illustrates a refrigerant recovery device 10. The refrigerant recovery device 10 is connected to an external refrigeration equipment 12 through a valve block 14. The valve block 14 comprises valves, which are adapted to establish a connection between the various components of the refrigerant recovery device 10 and refrigeration equipment 12. The valves in the valve block 14 are switched from a closed to an open position so as to establish a connection between a compressor 16 and a refrigerant tank 18 of the refrigeration equipment 12. The refrigerant recovery device 10 is used to recover refrigerant as well as to recharge refrigerant into the refrigeration equipment 12. The recovery of refrigerant from the refrigeration equipment 12 and storing of refrigerant by the refrigerant recovery device 12 is done through a refrigerant recovery path 20. The recharging of refrigerant from the refrigerant recovery device 12 to refrigeration equipment is done through a refrigerant recharge path 22. In the refrigerant recharge path 22 the refrigerant flows from the refrigerant tank 18 is heated by the heating element 24 and recharged to the refrigeration equipment 12.

Refrigeration equipments 12 are widely used in many applications including air conditioning systems, refrigerators and the like. These refrigeration equipments 12 use a refrigerant which provide cooling to an area or room in which they are fitted. The working principle of the refrigerant in the refrigeration equipment is that it absorbs heat while passing through various components of the refrigeration equipment. This cools the air around the refrigeration equipment and the cool air is then blown to the area or room where the refrigeration equipment is installed.

Due to prolonged usage of the refrigerant in the refrigeration equipment 12 the ability of the refrigerant to cool is reduced. Also there is a possibility that the refrigerant get contaminated with oil and moisture, which also reduces the ability of the refrigerant to cool the area or room where the refrigeration equipments 12 are installed. Hence it is required that the refrigerant is removed from the refrigeration equipment 12 and is recharged with new refrigerant. For the purpose of recovering the refrigerant and recharging the refrigerant a refrigerant recovery device 10 is used.

The refrigerant recovery device 10 is usually a stand alone device which is connected to the refrigeration equipment 12 while the refrigeration equipment 12 is being serviced. The refrigerant recovery device 10 comprises at least, a valve block 14, a compressor 16 and a refrigerant tank 18. The valve block 14 comprises valves, which are usually solenoid valves. The valves of the valve block 14 can be switched from a closed position to an open position, thereby establishing connection between the various components of the refrigerant recovery device 10. The valves in the valve block 14 can be switched from a closed position to an open position to establish a connection between the refrigerant recovery device 10 and the refrigeration equipment 12. The compressor 16 is a device which is capable of receiving fluid or gas at a particular pressure and increases the pressure of the fluid or gas that is received. A heating element 24 may be a electric heating coil wound around the tube through which the refrigerant is recharged to the refrigeration equipment 12. The heating element 24 increases the temperature of the refrigerant and the state of the refrigerant changes from liquid to gas. Due to the change of state of the refrigerant the pressure of the refrigerant that is recharged to the refrigeration equipment 12 also increases. The refrigerant tank 18 is a tank where the recovered refrigerant is store. The stored refrigerant is reused by recharging the refrigerant to the refrigeration equipment 12.

While servicing refrigeration equipment 12 three particular tasks are involved viz (i) recovery of the refrigerant from the refrigeration equipment 12, (ii) evacuation of air and moisture from the refrigeration equipment 12 and (iii) refilling or recharging the refrigeration equipment 12 with clean refrigerant. The method used by a conventional refrigerant recovery device in the three tasks can be explained as follows. The valve block 14 establishes a connection between the refrigerant recovery device 10 and the refrigeration equipment 12. When the refrigerant recovery device 10 is switched on the compressor 16 is able to recover the refrigerant from the refrigeration device 12. The recovered refrigerant is stored in the refrigerant tank 18. A vacuum pump 16 is used to evacuate the refrigeration device 10. Once the refrigeration equipment 12 is evacuated the air and moisture and remaining recovered refrigerant is released to the atmosphere. After the evacuation the refrigeration equipment 12 is recharged with refrigerant from the refrigerant tank 18. One disadvantage of this method of recovery and recharge is that the remaining refrigerant which is removed from the refrigeration equipment using the vacuum pump is released to the atmosphere. The release of these refrigerants to the atmosphere is harmful. It is necessary that the amount of refrigerant released in the atmosphere should be minimized.

Also when the refrigeration equipment 12 is in use there is a possibility that some amount of refrigerant gets stuck at some corners in the refrigeration equipment. When the refrigerant is being recovered this residual refrigerant which is stuck in the refrigeration equipment cannot be removed. Hence the amount of refrigerant that has to be recharged to the refrigeration equipment will be miscalculated. Thus extra refrigerant will have to be recharged which increases the cost for recharging refrigerant.

In accordance with this invention the refrigerant recovery device 10 is able to recover additional residual refrigerant which may be stuck in the refrigeration equipment 12. This reduces the amount of refrigerant that is released to the atmosphere. The method of recovering refrigerant in accordance with this invention can be explained as follows.

A connection is established between the refrigerant recovery device 10 and the refrigeration equipment 12 through the valve block 14 for performing a main recovering process. At least one valve in the valve block is switched to an open position for this purpose. Once the connection is established recovery of the refrigerant from the refrigeration equipment is initiated through the refrigerant recovery path 20 by switching on the compressor. In the refrigerant recovery path 20 the refrigerant flows from the refrigeration equipment 12 through the valve block 14 to the compressor 16 and is stored in the refrigerant tank 18. When the compressor 16 is switched on the pressure in the inlet path of the compressor 16 is lower that the pressure in the refrigeration equipment 12. The refrigerant flows from the high pressure refrigeration equipment 12 to the low pressure inlet path of the compressor. The compressor 16 increases the pressure of the refrigerant and is stored in the refrigerant tank 18. Once the refrigerant is recovered from the refrigeration equipment 12 to the refrigerant tank the valve in the valve block 14 is switched to closed position.

After recovering the refrigerant from the refrigeration equipment 12 by the main recovering process described above, a temporary refrigerant recharge process takes place in which a small amount of heated refrigerant from the refrigerant tank 18 is recharged into the refrigeration equipment 12. For this purpose a connection is established between the refrigerant tank 18 and the refrigeration equipment 12 through the refrigerant recharge path 22. In the refrigerant recharge path 22 the refrigerant flows from the refrigerant tank 18 through the heating element 24, valve block 14 to the refrigeration equipment 12. The small amount of heated refrigerant at the temporary refrigerant recharge process represents less than 20% of the whole capacity of the refrigerant inside of the refrigeration equipment 12, especially less than 10% of the whole capacity of the refrigerant inside of the refrigeration equipment 12. The small amount of heated refrigerant is introduced into the refrigeration equipment 12 in more than one pulse, for example in three pulses.

When the refrigerant passes along the heating element 24, there is a sudden increase in the temperature and pressure of the refrigerant. Here the temperature and pressure of the refrigerant is higher than temperature and pressure of the refrigerant during a conventional recharge operation. The increased pressure and temperature of the recharged refrigerant ensures that the refrigerant is quickly recharged to the refrigeration equipment. Further due the high temperature and pressure the state of the refrigerant recharged into the refrigeration equipment changes from liquid to gaseous.

When the refrigerant enters the refrigeration equipment 12 it changes the state of the residual refrigerant that is present in the refrigeration equipment to gaseous state. This happens due to the increase in temperature and consequent increase in pressure of the refrigerant inside the refrigeration equipment 12. Due to change in state of the residual refrigerant the high temperature and high pressure refrigerant from the refrigeration equipment can be easily recovered from the refrigeration equipment 12. Introducing high pressure and high temperature refrigerant into the refrigeration equipment 12 increases the pressure and temperature inside the refrigeration equipment 12. This makes recovery of refrigerant from the refrigeration equipment 12 easier.

After the temporary refrigerant recharge process is finished an additional recovering process is performing for additionally emptying of a residual refrigerant from the refrigeration equipment (12). For recovering the residual refrigerant in the additional recovering process at least one valve in the valve block is switched to an open position for this purpose. Once the connection is established recovery of the refrigerant from the refrigeration equipment is initiated through the refrigerant recovery path 20 by switching on the compressor. When the compressor is switched on the pressure in the inlet path of the compressor is lower than the pressure in the refrigeration equipment 12. The refrigerant flows from the high pressure refrigeration equipment to the low pressure inlet path of the compressor. The compressor increases the pressure of the refrigerant and is stored in the refrigerant tank 18. Once the refrigerant is recovered from the refrigeration equipment 12 to the recovery tank the valve in the valve block 14 is switched to closed position.

An advantage of introducing refrigerant that is heated using the heating element is that it increases the temperature of the refrigerant being recharged into the refrigeration equipment 12 consequently pressure also increases. This leads to change in state of the refrigerant in the refrigeration equipment 12 from liquid state to gaseous state. It is easier to recover refrigerant which is in gaseous state. As pressure and temperature inside the refrigeration equipment 12 is higher than usual. Hence, the compressor 12 can easily and quickly recover refrigerant. The compressor 16 will have to be switched on for a shorter period of time to recover additional refrigerant from the refrigeration equipment 12. Also due to high temperature and pressure the liquid refrigerant that may be stuck in various parts of the refrigeration equipment is converted to gaseous state and are easily recovered. This method of recovering additional refrigerant ensures more than 95% refrigerant of the refrigerant from the refrigeration equipment 12. Another advantage of this method is that since additional refrigerant is recovered during the recovery process the total amount of refrigerant released into the atmosphere is reduced.

Claims

1. A method for recovering refrigerant from an external refrigeration equipment by a refrigerant recovery device, with the refrigerant of the external refrigeration equipment flowing from the refrigeration equipment through a refrigerant recovery path to a refrigerant tank of the recovery device, comprising:

recovering the refrigerant from the refrigeration equipment in a main recovering process;

recharging a small amount of heated refrigerant into the refrigeration equipment in a temporary refrigerant recharge process; and

performing an additional recovering process for emptying of a residual refrigerant from the refrigeration equipment after finishing the temporary refrigerant recharge process.

2. The method as claimed in claim 1, wherein, to perform the temporary refrigerant recharge process, the refrigerant recovery path is closed and a recharge path which connects the tank with the refrigeration equipment is opened.

3. The method as claimed in claim 2, further comprising:

establishing a connection between the refrigerant recovery device and the refrigeration equipment by switching on at least one valve in a valve block;

creating a low pressure at the inlet path of a compressor by switching on said compressor;

recovering the refrigerant from said refrigeration equipment to a refrigerant tank through the refrigerant recovery path comprising at least said valve block, said compressor and said refrigerant tank by the main recovering process;

switching off said compressor;

recharging the refrigerant from said refrigerant tank to said refrigeration equipment by keeping a heating element switched on through the refrigerant recharge path comprising at least said valve block and said refrigerant tank by the refrigerant recharge process;

switching off said heating element;

creating a low pressure at the inlet path of said compressor by switching on said compressor; and

emptying the rest of the refrigerant from said refrigeration equipment through said refrigerant recovery path by the additional recovering process.

4. The method as claimed in claim 1, wherein the increase in temperature of the refrigerant by the temporary refrigerant recharge process causes change of state of the refrigerant recharged to said refrigeration equipment from liquid to gaseous.

5. The method as claimed in claim 4, wherein the change in state of the refrigerant causes increase in pressure of the refrigerant recharged to said refrigeration equipment.

6. The method as claimed in claim 1, wherein said temporary refrigerant recharge process increases the temperature inside the refrigeration equipment.

7. The method as claimed in claim 1, wherein said temporary refrigerant recharge process changes the state of the refrigerant inside the refrigeration equipment.

8. The method as claimed in claim 7, wherein said change in state of the refrigerant causes increase in pressure of the refrigerant in said refrigeration equipment.

9. The method as claimed in claim 7, wherein performing said temporary refrigerant recharge process to said refrigeration equipment recovers additional refrigerant that is stuck in different parts of the refrigeration equipment.

10. The method as claimed in claim 1, wherein the small amount of heated refrigerant is introduced into the refrigeration equipment in more than one pulse.