JP2000186863A - Freezing air conditioning apparatus using combustible refrigerant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve energy efficiency of an instrument and reduce an influence upon a refrigerant being leaked in a freezing air conditioning apparatus using a combustible refrigerant having a very small bad influence to global environment. SOLUTION: In a refrigerations cycle where a compressor 1, a condenser 2, a first capillary tube 3, an evaporator 4 are coupled in order through a refrigerant piping communicating these members using a combustible refrigerant as a refrigerant, an oil separator 20 is provided on a piping extending between an outlet of the compressor 1 and the condenser 2. Further, an opening/closing valve is provided for interrupting a high pressure section and a low pressure section upon interruption of the compressor. Moreover, an odorant or a colorant is added to a lubricating oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration and air-conditioning system using a flammable refrigerant which does not adversely affect the global environment such as depletion of the ozone layer and global warming.

[0002]

2. Description of the Related Art Freon-based refrigerants are currently used as refrigerants in refrigeration and air-conditioning systems such as refrigerators and refrigerators.
Among the CFC-based refrigerants, CFC-based and HCFC-based refrigerants are degrading the ozone layer, and are being switched to HFC-based CFC refrigerants. In home refrigerators, HFC
R134a, which is a system refrigerant, is widely used.

FIG. 7 is a diagram showing a refrigerant circuit configuration of a home refrigerator. In the drawing, reference numeral 1 denotes a compressor, 2 denotes a condenser, 3 denotes a capillary tube as a throttle device, and 4 denotes an evaporator. Also capillary 3
And the suction pipe of the compressor 1 are soldered to form a heat recovery heat exchanger 10. Further, a header 11 for storing excess refrigerant generated at the time of load change or the like is provided in the outlet pipe of the evaporator 4.

[0004] Next, the operation of the conventional home refrigerator using a CFC-based refrigerant will be described with reference to a pressure-enthalpy diagram shown in FIG. The high-temperature and high-pressure refrigerant vapor exiting the compressor 1 (point A in the figure) flows into the condenser 2 and is cooled by outside air and condensed to a gas-liquid two-phase state (B in the figure).
point). The gas-liquid two-phase refrigerant that has exited the condenser 2 flows into the capillary tube 3 and is decompressed, and becomes a low-pressure gas-liquid two-phase refrigerant. Since the capillary 3 forms the suction pipe of the compressor 1 and the heat recovery heat exchanger 10, the refrigerant passing through the capillary 3 is cooled by the suction pipe of the compressor 1 (point C in the figure). The low-pressure gas-liquid two-phase refrigerant flows into the evaporator 4 and cools the inside of the refrigerator, enters a low-pressure saturated vapor state, and flows out of the evaporator 4 (point D in the figure). The low-pressure vapor refrigerant flows into the heat recovery heat exchanger 10 via the header 11, is heated by the refrigerant passing through the capillary 3, becomes low-pressure superheated vapor, and is sucked into the compressor 1 again (E in the figure). point).

[0005] Lubricating oil is sealed in the compressor 1, and the lubricating oil circulates in the refrigeration cycle together with the refrigerant. Further, surplus refrigerant generated due to a change in the ambient temperature where the refrigerator is installed or the like accumulates in the header 11.

However, this HFC-based refrigerant is a substance that promotes global warming, and the use of natural refrigerants such as hydrocarbon refrigerants and ammonia, which do not deteriorate the global environment, as refrigerants for refrigeration and air conditioning systems is being studied. These natural refrigerants are flammable refrigerants, and a refrigerator using such refrigerants is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-178481. As a refrigerant for the refrigerator, a hydrocarbon-based refrigerant such as propane or butane, which has a very small effect on global warming, but is flammable is used. Further, a flammable refrigerant detection sensor is installed near the refrigerant pipe connection part of the refrigerator.

When the flammable refrigerant leaks from the piping connection of the refrigeration cycle or the like, the flammable refrigerant detection sensor detects this and transmits a stop signal to the compressor 1 so as to be controlled. It is controlled so that even if one flammable refrigerant leaks, it does not lead to an explosion.

[0008]

In the above-mentioned conventional refrigeration and air-conditioning apparatus, in order to suppress global warming, a hydrocarbon-based refrigerant having a very small effect on global warming is used as a refrigerant for the refrigeration and air-conditioning apparatus. I have. However, in order to control global warming, not only the global warming of the refrigerant itself,
It is also important to control global warming due to the use of electricity in refrigeration and air conditioning equipment. That is, improving the energy efficiency of the refrigeration and air conditioning equipment is also an important issue.

Further, the hydrocarbon refrigerant has high compatibility with the lubricating oil, and a large amount of the refrigerant dissolves in the lubricating oil in the compressor to lower the viscosity. The efficiency of the refrigeration cycle may decrease due to an increase in pressure loss or a decrease in the heat transfer performance of the heat exchanger.

Furthermore, when a flammable refrigerant is used, the amount of refrigerant charged into the refrigeration / air-conditioning system is reduced, refrigerant leakage from the equipment is suppressed, or in the event of a refrigerant leakage, the It is important to find the spot and repair it.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and is directed to a refrigeration and air-conditioning system using a flammable refrigerant having a very small adverse effect on the global environment.
It is an object of the present invention to obtain a refrigeration / air-conditioning apparatus capable of improving the energy efficiency of equipment and suppressing leakage of a refrigerant or reducing the influence of leakage.

[0012]

According to a first aspect of the present invention, there is provided a refrigeration / air-conditioning apparatus comprising: a compressor, a condenser, a throttle device, and an evaporator, which are sequentially arranged by a refrigerant pipe for circulating a flammable refrigerant as a refrigerant. In the refrigeration cycle connected, an oil separator is provided in a pipe between the compressor outlet and the condenser.

In a refrigeration / air-conditioning apparatus according to a second aspect of the present invention, the compressor is of a low-pressure shell type.

A refrigeration air conditioner according to a third aspect of the present invention is a refrigeration cycle in which a compressor, a condenser, a throttle device, and an evaporator are sequentially connected by a refrigerant pipe through which a combustible refrigerant flows as a refrigerant. , An on-off valve for shutting off a high-pressure portion from the compressor outlet to the expansion device and a low-pressure portion from the expansion device to the compressor inlet when the compressor is stopped.

In a refrigeration / air-conditioning apparatus according to a fourth aspect of the present invention, a compressor, a condenser, a capillary, and an evaporator are sequentially connected by a refrigerant pipe for circulating using a combustible refrigerant as a refrigerant, and further, an evaporator outlet is provided. In a refrigeration cycle having a heat recovery heat exchanger in which heat is exchanged between a pipe from a pipe to a compressor inlet and a capillary, the heat recovery heat exchanger is constituted by a double tube heat exchanger.

A refrigeration / air-conditioning apparatus according to a fifth aspect of the present invention is such that the inner tube of the double tube heat exchanger is a capillary tube and the annular portion of the double tube heat exchanger is a suction refrigerant pipe of a compressor. is there.

A refrigeration air conditioner according to a sixth aspect of the present invention is a refrigeration cycle in which a compressor, a condenser, a throttle device, and an evaporator are sequentially connected by a refrigerant pipe through which a combustible refrigerant flows as a refrigerant. In the above, the pipe from the outlet of the evaporator to the inlet of the compressor is constituted by a single pipe having no welding portion.

A refrigeration air conditioner according to a seventh aspect of the present invention is a refrigeration cycle in which a compressor, a condenser, a throttling device, and an evaporator are sequentially connected by a refrigerant pipe through which a combustible refrigerant flows as a refrigerant. Wherein the odorant is added to the lubricating oil of the compressor.

A refrigeration cycle air conditioner according to an eighth aspect of the present invention is a refrigeration cycle in which a compressor, a condenser, a throttle device, and an evaporator are sequentially connected by a refrigerant pipe through which a combustible refrigerant flows as a refrigerant. Wherein the coloring agent is added to the lubricating oil of the compressor.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a refrigerant circuit diagram of a home refrigerator-freezer showing an example of an embodiment of the present invention, and the same parts as those of the conventional apparatus are denoted by the same reference numerals. In the figure, 1 is a compressor, 2 is a condenser, 3 is a first capillary tube as a throttle device, and 4 is an evaporator. An oil separator 20 is provided in a pipe between the compressor 1 and the condenser 2,
The lubricating oil separated by the oil separator is connected to a suction pipe of the compressor 1 via a first solenoid valve 21 and a second capillary tube 22. The compressor 1 uses a low-pressure shell compressor in which the pressure inside the compressor container is low. Further, as the refrigerant of the refrigerator, a hydrocarbon-based refrigerant R600a (isobutane) which exhibits flammability but has a very small adverse effect on global warming is used. Mineral oil is sealed in the compressor 1 as lubricating oil for lubricating sliding portions of the compressor.
The compressor 1 uses a low-pressure shell compressor in which the inside of the compressor is in a low-pressure state.

Next, the operation will be described. In a home refrigerator-freezer, basically, the temperature inside the refrigerator is controlled to be constant by intermittent operation of a compressor. Therefore, here, the operation during the operation of the compressor will be described first. During operation of the compressor, the first solenoid valve 21 is kept open. The high-temperature and high-pressure refrigerant vapor that has exited the compressor 1 flows into the oil separator 20, where it is separated into refrigerant vapor and lubricating oil. The lubricating oil separated by the oil separator 30 stays in the lower part of the oil separator 30 due to gravity and returns to the suction pipe of the compressor 1 via the first solenoid valve 21 and the second capillary tube 22. The refrigerant vapor separated by the oil separator 30 flows into the condenser 2 and is cooled by outside air and condensed to a gas-liquid two-phase state.

The gas-liquid two-phase refrigerant leaving the condenser 2 is supplied to the capillary 3
Into a low-pressure gas-liquid two-phase refrigerant. Since the capillary 3 constitutes the suction pipe of the compressor 1 and the heat recovery heat exchanger 10, the refrigerant passing through the capillary 3 is cooled by the suction pipe of the compressor 1. The low-pressure gas-liquid two-phase refrigerant flows into the evaporator 4, cools the inside of the refrigerator, becomes a low-pressure saturated vapor state, and flows out of the evaporator 4. The low-pressure vapor refrigerant flows into the heat recovery heat exchanger 10, is heated by the refrigerant passing through the capillary 3, becomes low-pressure superheated steam, and is sucked into the compressor 1 again. On the other hand, while the compressor is stopped, the first solenoid valve 30 is kept closed.

In the present embodiment, the use of a low-pressure shell compressor significantly reduces the amount of flammable refrigerant R600a in the refrigeration cycle in the refrigeration cycle as compared with the high-pressure shell compressor, and reduces the amount of refrigerant that leaks. The leakage amount and its effects are reduced. In general, hydrocarbon-based refrigerants have greater mutual solubility with mineral oil than fluorocarbon-based refrigerants. FIG. 2 shows the solubility of R600a, which is a hydrocarbon-based refrigerant, and mineral oil. The horizontal axis represents pressure, the vertical axis represents solubility, and the curve parameter in the figure represents temperature.

That is, the solubility of the hydrocarbon-based refrigerant in the mineral oil is determined by the pressure and the temperature. As shown in FIG. 2, the higher the pressure and the lower the temperature, the higher the solubility. The high pressure of a refrigerator using a general R600a is 4.3 kg.
/ Cm ² abs. , Low pressure is 0.45 kg / cm ² abs.
And in the case of a high-pressure shell compressor, the pressure in the compressor vessel in which lubricating oil is sealed is 4.3 kg / cm ² ab
s. The pressure in the compressor vessel of the low-pressure shell compressor is 0.4
5 kg / cm ² abs. Becomes

Now, assuming that the temperature of the compressor container is 60 ° C.,
2, the solubility of the high-pressure shell compressor is about 21% (point a in FIG. 2), and the solubility of the low-pressure shell compressor is about 3% (b in FIG. 2).
Point), and the solubility inside the compressor can be greatly reduced by using a compressor having a low-pressure shell. If the solubility inside the compressor can be significantly reduced, the amount of refrigerant dissolved and present in the lubricating oil inside the compressor can be significantly reduced,
As a result, it is possible to reduce the amount of the flammable refrigerant to be charged into the refrigeration cycle, and it is possible to reduce the leakage amount at the time of refrigerant leakage and its influence.

In this embodiment, the oil separator 20 is provided in the discharge pipe of the compressor 1 to greatly reduce the amount of lubricating oil circulating in the refrigeration cycle. The lubricating oil circulating in the refrigeration cycle adheres to the inside of the refrigerant pipe, causing an increase in refrigerant pressure loss and a decrease in heat transfer characteristics of the heat exchanger, resulting in a decrease in energy efficiency of the refrigeration cycle. In general,
Since the low-pressure shell compressor discharges the refrigerant directly from the compression chamber inside the compressor to the discharge pipe, the oil discharge amount is larger than that of the high-pressure shell compressor.

Therefore, in order to reduce the influence of leakage of the refrigerant, in the refrigerating cycle employing a low-pressure shell compressor in which the solubility inside the compressor is greatly reduced and the amount of refrigerant charged is reduced, the oil separator 20 is connected to the compressor. Provided in the discharge pipe, the amount of lubricating oil circulating in the refrigeration cycle is greatly reduced, preventing a decrease in energy efficiency due to an increase in pressure loss and a decrease in heat transfer characteristics.

Also, by providing the oil separator 20 to reduce the amount of lubricating oil circulating in the refrigeration cycle, the amount of lubricating oil present in the refrigeration cycle can also be reduced. As a result, the amount of lubricating oil sealed in the compressor can be reduced. Can also be reduced. By reducing the amount of lubricating oil inside the compressor, the amount of refrigerant dissolved in the lubricating oil is reduced, so that the amount of refrigerant charged into the refrigeration cycle can be further reduced, and the safety at the time of refrigerant leakage is further improved. . Further, since the amount of the lubricating oil to be initially charged is small, the cost of the lubricating oil can be reduced, and an inexpensive system can be provided.

In the present embodiment, the first solenoid valve 21 provided in the oil return pipe of the oil separator 20 is opened during the operation of the compressor, and is separated by the oil separator 20 during the operation of the compressor. Although the oil is continuously returned to the suction pipe of the compressor 1, the first solenoid valve 21 is closed during the operation of the compressor, and the oil separated during the operation of the compressor is stored in the oil separator 20. You may make it. At this time, the oil stored in the oil separator 20 may be returned to the compressor suction pipe by opening the first solenoid valve 21 for a predetermined time when the compressor is stopped.

In this embodiment, the case where the flammable hydrocarbon refrigerant isobutane (R600a) is used as the refrigerant has been described. However, the present invention is not limited to this, and the hydrocarbon refrigerant such as butane (R600) and propane (R290) is used. It may be a natural refrigerant such as a hydrogen refrigerant or ammonia, or a mixed refrigerant thereof. Also, R32 and R152a, etc.
An HFC-based Freon refrigerant having a small global warming potential, or a mixed refrigerant thereof may be used.

In this embodiment, the case where mineral oil is used as the lubricating oil has been described. However, the present invention is not limited to this, and alkylbenzene, ester oil, ether oil, PA
It may be a synthetic oil such as G oil.

Embodiment 2 FIG. FIG. 3 is a refrigerant circuit diagram of a refrigeration / air-conditioning apparatus showing another example of the embodiment of the present invention. In a pipe between the condenser 2 and the first capillary 3, a second solenoid valve 30 is provided. A check valve 31 for closing the flow of the refrigerant from the compressor 1 to the evaporator 4 is provided in a pipe between the evaporator 4 and the compressor 1. As a refrigerant of the refrigerator, a hydrocarbon-based refrigerant R600a (isobutane) which exhibits flammability but has a very small adverse effect on global warming is used. Note that the same components as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

In this embodiment, during the operation of the compressor, the second
The solenoid valve 30 is opened, and operation is performed with the same refrigerant flow as in the first embodiment. When the compressor is stopped, the second solenoid valve 30 is closed to prevent the refrigerant from moving from the high pressure section through the first capillary tube 3 to the low pressure section. Check valve 31
Prevents the refrigerant from moving from the high pressure section through the compressor to the low pressure section when the compressor is stopped.

In a home refrigerator which controls the inside of the refrigerator to a constant temperature by the intermittent operation of the compressor, the energy efficiency of the refrigerator is reduced when the refrigerant moves from the high pressure section to the low pressure section when the compressor is stopped. This is because the evaporator is warmed by the movement of the refrigerant when the compressor is stopped, the amount of refrigerant in the high-pressure section is reduced, and the refrigerant is in a shortage state when the compressor is restarted, and the inefficient operating state continues for a while.

The flow rate of the hydrocarbon-based refrigerant through a portion having a large flow resistance such as a nozzle tends to increase as compared with the CFC-based refrigerant. Therefore, in a conventional refrigerator using a chlorofluorocarbon-based refrigerant, the flow resistance of the first capillary and the compressor 1 suppresses the movement of the refrigerant between the high-pressure part and the low-pressure part. The flow resistance of the compressor is not sufficient, and the amount of refrigerant transfer from the high-pressure section to the low-pressure section increases as compared with the CFC-based refrigerant.

The volume flow rate G of gas passing through the nozzle is G = v * F * {2 / (κ + 1)}^{{ 1 / ( κ -1) }}* [2 *
{Κ / (κ + 1)｝ * (P / v)]^0.5  Is required. Where F is the nozzle cross-sectional area, κ is the specific heat ratio,
P is high pressure and v is specific volume. Using this formula,
High pressure part of elementary refrigerant R600a and chlorofluorocarbon refrigerant R134a
Calculate the moving refrigerant flow rate in the low pressure section from

The condensing temperature immediately after stopping the compressor of the refrigerator is 30
° C and the evaporation temperature at -30 ° C, the physical properties of R600a are κ = 1.138, P = 404 kPa, and v = 0.09.
561 m ³ / kg, and the physical property value of R134a is κ =
1.198, P = 770 kPa, v = 0.02667m
³ / kg. Substituting the above equations for these physical properties, R6
When the flow rate of the moving refrigerant at the same nozzle cross-sectional area of 00a and R134a is obtained, _G600a / _G134a = 1.22. That is, the flow rate of the moving refrigerant from the high pressure section to the low pressure section of R600a is 22% larger than that of R134a, and the energy efficiency of the refrigerator using R600a is R1.
34a.

Therefore, in the present embodiment, the R600a
The second solenoid valve 30 and the check valve 3 prevent the refrigerant from moving from the high pressure section to the low pressure section when the compressor of the refrigerator is stopped.
1 is provided. As a result, a decrease in the energy efficiency of the refrigerator due to the movement of the refrigerant from the high-pressure section to the low-pressure section when the compressor is stopped can be prevented, and a refrigerating refrigerator using a highly energy-efficient flammable refrigerant can be provided.

In the present embodiment, the solenoid valve is provided in the pipe between the condenser 2 and the first capillary tube 3 and the check valve is provided in the pipe between the evaporator 4 and the compressor 1. However, the present invention is not limited to this. Not a thing,
Any configuration may be used as long as the refrigerant can be prevented from moving from the high pressure section to the low pressure section when the compressor is stopped. For example, the check valve 31 may be an electromagnetic valve. Alternatively, a differential pressure valve that opens the second solenoid valve 30 when the differential pressure before and after the valve is large and closes when the differential pressure before and after the valve is small may be used. Further, only one of the second solenoid valve 30 and the check valve 31 may be used.

Embodiment 3 FIG. 4 is a refrigerant circuit diagram of a refrigeration / air-conditioning apparatus showing another embodiment of the present invention. In the heat recovery heat exchanger 10, the inner tube is a first capillary tube and the annular portion is a compressor 1
It consists of a double pipe heat exchanger which is used as a suction pipe. Note that the same components as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

In this embodiment, since the heat recovery heat exchanger 10 is constituted by a double tube heat exchanger, the heat exchange performance can be improved as compared with the conventional solder contact type heat exchanger. The heat recovery heat exchanger becomes compact. By making the heat recovery heat exchanger compact, the internal volume of the heat recovery heat exchanger is also reduced, the amount of refrigerant is reduced, and safety at the time of refrigerant leakage can be further improved. In addition, since the heat recovery heat exchanger can be manufactured without making contact with solder, recyclability is also improved.

In this embodiment, the heat recovery heat exchanger 10 is constituted by a double-tube heat exchanger in which the inner tube is the first capillary tube and the annular portion is the suction pipe of the compressor 1, so that the first capillary tube is formed. The heat of the low-temperature refrigerant passing through the refrigerant is surely transmitted to the refrigerant flowing through the annular portion, and no heat exchanger loss occurs, so that the energy efficiency of the refrigerator can be further improved. Further, by using both the inner tube and the capillary tube, a compact double tube heat exchanger can be realized.

Embodiment 4 FIG. FIG. 5 is a refrigerant circuit diagram of a refrigeration / air-conditioning apparatus showing another embodiment of the present invention. The outlet pipe of the evaporator 4 does not have a header in the conventional apparatus, and the outlet pipe of the evaporator 4 is not provided. It is composed of one pipe with no connection such as welding. Note that the same components as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

In this embodiment, the header at the outlet of the evaporator 4 is abolished, and the outlet pipe of the evaporator 4 is constituted by a single pipe having no connection such as welding. It is possible to reduce the occurrence of refrigerant leakage due to a defective connection portion, and to realize a highly reliable refrigeration / air-conditioning apparatus.

In the present embodiment, the excess refrigerant generated at the time of a load change such as a change in ambient temperature where the refrigerator is placed cannot be stored, but the refrigerant density of R600a is smaller than that of R134a, and R600a is smaller than R134a. Is smaller than R134a, the amount of surplus refrigerant generated when the load changes is also small. Further, since the heat recovery heat exchanger 10 is a double-pipe heat exchanger having a high heat exchange performance, even if a small amount of excess refrigerant is generated due to a change in load, the reliability decreases due to liquid back to the compressor and the compressor suction piping There is no problem such as dew.

Embodiment 5 FIG. FIG. 6 is a refrigerant circuit diagram of a refrigeration / air-conditioning apparatus showing another example of the embodiment of the present invention. The same components as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted. I do. In the present embodiment, an odorant is added to the lubricating oil sealed for lubricating the sliding parts of the compressor. Therefore, if a flammable refrigerant leaks from the refrigeration cycle, the lubricating oil also leaks together with the refrigerant, so that the odor can be used to easily identify the refrigerant leakage and the lubricating oil leakage, and the user can take appropriate measures. Measures can be taken. Also, when repairing a refrigerator in which a leak has occurred, the leak site can be easily specified, so that appropriate processing can be quickly performed.

In this embodiment, an example in which an odorant is added to lubricating oil has been described. However, an adhering agent is added to lubricating oil so that refrigerant leakage can be detected by the color of oil leaking with refrigerant. The same effect can be obtained. For example, a red coloring agent is used as the adhesive, and the following components are typical. Chemical name: Azo and diazo compounds (the following mixtures) (dyes) Reference numbers of existing chemical substances according to the Chemical Substances Control Law 5th Class 3087 (Solvent Red 23) 5th Class 5049 (Solvent Orange 73) Ingredients And content: dye component 60 to 70% xylene (solvent) 30 to 40% The chemical structure of these azo and diazo dyes is characterized by:
It has an aromatic ring and a -N = N- bond in the molecule.

[0048]

As described above, the refrigeration / air-conditioning apparatus according to the first aspect of the present invention comprises a compressor, a condenser, a throttling device, and an evaporator which are sequentially connected by a refrigerant pipe through which a combustible refrigerant flows as a refrigerant. In this refrigerating cycle, an oil separator is provided in the pipe between the compressor outlet and the condenser, so that a decrease in energy efficiency due to an increase in pressure loss and a decrease in heat transfer performance can be suppressed, resulting in a highly efficient refrigeration. An air conditioner can be provided. In addition, it is possible to reduce the influence at the time of leakage due to the reduction of the refrigerant charging amount, and to provide an inexpensive system.

The refrigeration / air-conditioning apparatus according to the second invention is
Since the compressor is of a low-pressure shell type, the amount of refrigerant to be charged into the refrigeration and air-conditioning apparatus can be greatly reduced, and the effect of leakage of the refrigerant can be reduced.

The refrigeration / air-conditioning apparatus according to the third invention is characterized in that:
In a refrigeration cycle in which a compressor, a condenser, a throttle device, and an evaporator are sequentially connected by a refrigerant pipe that circulates using a flammable refrigerant as a refrigerant, a high-pressure section from the compressor outlet to the throttle device when the compressor is stopped. And an on-off valve that shuts off the low-pressure section from the expansion device to the compressor inlet. This prevents refrigerant from moving from the high-pressure section to the low-pressure section when the compressor is stopped, and provides a highly energy-efficient refrigeration and air-conditioning system. Can be provided.

The refrigeration / air-conditioning apparatus according to the fourth invention is characterized in that:
Heat recovery by connecting the compressor, condenser, capillary, and evaporator sequentially with refrigerant piping that circulates using a flammable refrigerant as the refrigerant, and further exchanging heat between the piping from the evaporator outlet to the compressor inlet and the capillary. In a refrigeration cycle with a heat exchanger, the heat recovery heat exchanger is composed of a double-tube heat exchanger, so that the effects of leakage due to the reduction of the refrigerant charge can be reduced and the recyclability is improved. Can be.

A refrigeration / air-conditioning apparatus according to a fifth aspect of the present invention
Since the inner tube of the double tube heat exchanger is a capillary tube and the annular portion of the double tube heat exchanger is the suction refrigerant pipe of the compressor,
Energy efficiency can be further improved, and a compact double tube heat exchanger can be realized.

The refrigeration / air-conditioning apparatus according to the sixth aspect of the present invention
In a refrigeration cycle in which a compressor, a condenser, a throttle device, and an evaporator are sequentially connected by a refrigerant pipe that circulates using a flammable refrigerant as a refrigerant, a pipe from an evaporator outlet to a compressor inlet has no welded portion. Since it is composed of a single pipe, it is possible to reduce the occurrence of refrigerant leakage due to defective pipe connections such as poor welding, and to realize a highly reliable refrigeration / air-conditioning apparatus.

The refrigeration / air-conditioning apparatus according to the seventh aspect of the present invention
In a refrigeration cycle in which a compressor, a condenser, a throttle device, and an evaporator are sequentially connected by a refrigerant pipe that circulates using a flammable refrigerant as a refrigerant, an odorant is added to lubricating oil of the compressor. Therefore, the leakage of the refrigerant can be easily known by the smell, and the user can accurately know the leakage of the refrigerant. Also, when repairing a refrigerator in which a leak has occurred, the leak site can be easily specified, so that appropriate processing can be quickly performed.

The refrigeration / air-conditioning apparatus according to the eighth invention is characterized in that:
In a refrigeration cycle in which a compressor, a condenser, a throttle device, and an evaporator are sequentially connected by a refrigerant pipe that circulates using a flammable refrigerant as a refrigerant, a coloring agent is added to lubricating oil of the compressor. In addition, the leakage of the refrigerant can be easily known by the color, and the user can accurately know the leakage of the refrigerant. Also, when repairing a leaked refrigerator,
Since the leak site can be easily specified, appropriate processing can be quickly performed.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration / air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 2 shows solubility curves of R600a and mineral oil.

FIG. 3 is a refrigerant circuit diagram of a refrigeration / air-conditioning apparatus according to Embodiment 2 of the present invention.

FIG. 4 is a refrigerant circuit diagram of a refrigeration / air-conditioning apparatus according to Embodiment 3 of the present invention.

FIG. 5 is a refrigerant circuit diagram of a refrigeration / air-conditioning apparatus showing Embodiment 4 of the present invention.

FIG. 6 is a refrigerant circuit diagram of a refrigerating air conditioner showing a fifth embodiment of the present invention.

FIG. 7 is a refrigerant circuit diagram of a conventional refrigeration / air-conditioning apparatus.

FIG. 8 is a characteristic diagram showing an operation of a conventional refrigeration / air-conditioning apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Compressor, 2 Condenser, 3 First capillary tube, 4
Evaporator, 10 heat recovery heat exchanger, 20 oil separator.

Continuation of the front page (72) Inventor Masahiro Nakayama 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Maruyama, etc. 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Co., Ltd. In company

Claims (8)

[Claims] 1. A compressor, a condenser, a throttle device, and an evaporator,
In a refrigeration cycle sequentially connected by a refrigerant pipe that circulates using a flammable refrigerant as a refrigerant, a flammable refrigerant characterized by having an oil separator provided in a pipe between the compressor outlet and the condenser. Refrigeration air conditioner used. 2. The refrigeration and air-conditioning system using a flammable refrigerant according to claim 1, wherein the compressor is of a low-pressure shell type. 3. A compressor, a condenser, a throttle device, and an evaporator,
In a refrigeration cycle that is sequentially connected by a refrigerant pipe that circulates using a flammable refrigerant as a refrigerant, when the compressor is stopped, a high-pressure portion from the compressor outlet to the expansion device and from the expansion device to the compressor inlet. A refrigeration / air-conditioning system using a flammable refrigerant, comprising an on-off valve for shutting off a low-pressure section of the refrigeration system. 4. A compressor, a condenser, a capillary, and an evaporator are sequentially connected by a refrigerant pipe for flowing a combustible refrigerant as a refrigerant, and a pipe from an outlet of the evaporator to an inlet of the compressor and the capillary. A refrigeration cycle having a heat recovery heat exchanger in which heat exchange is performed between the heat recovery heat exchanger and the heat recovery heat exchanger, wherein the heat recovery heat exchanger is constituted by a double tube heat exchanger. 5. The double pipe heat exchanger according to claim 4, wherein the inner pipe of the double pipe heat exchanger is a capillary tube, and the annular portion of the double pipe heat exchanger is a suction refrigerant pipe of the compressor. A refrigeration air conditioner using a flammable refrigerant. 6. A compressor, a condenser, a throttle device, and an evaporator,
In a refrigeration cycle sequentially connected by a refrigerant pipe that circulates using a flammable refrigerant as a refrigerant, a pipe from the evaporator outlet to the compressor inlet is constituted by one pipe without a welded part. Refrigeration and air-conditioning systems using flammable refrigerants. 7. A compressor, a condenser, a throttle device, and an evaporator,
A refrigeration cycle using flammable refrigerant, wherein an odorant is added to lubricating oil of the compressor in a refrigeration cycle sequentially connected by refrigerant pipes that circulate using flammable refrigerant as refrigerant. 8. A compressor, a condenser, a throttle device, and an evaporator,
A refrigeration cycle using a flammable refrigerant, wherein a coloring agent is added to lubricating oil of the compressor in a refrigeration cycle sequentially connected by refrigerant pipes circulating using a flammable refrigerant as a refrigerant.