JP2014031915A - Refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle device, which uses a constant speed compressor and capillary tubes, capable of securing reliability of the compressor by suppressing the rise of a discharge temperature of the compressor at low cost at the time of an overload, even when it comes into a state of overload where the discharge temperature of the compressor surpasses a predetermined reference value because of the change in an environmental temperature and the like.SOLUTION: The refrigeration cycle device has a configuration in which a constant speed compressor 1 and capillary tubes 5 and 7 are used, and a heat exchange mechanism 8 for exchanging heat between a high pressure side cooling medium and a low pressure side cooling medium of the capillary tubes is installed. Thereby, even when it comes into a state of overload where a discharge temperature of the constant speed compressor 1 surpasses a predetermined reference value because of a change in an environmental temperature and the like, the rise of the discharge temperature of the compressor can be suppressed without using a solenoid valve, so that the refrigeration cycle device with high reliability can be achieved at low cost.

Description

  The present invention relates to a vapor compressor type refrigeration cycle apparatus.

  Conventionally, when a refrigeration system including an air conditioner is in an overload state in which the discharge temperature of the compressor exceeds a predetermined reference value due to a change in environmental temperature during the refrigeration cycle operation, There is a problem in reliability such as alteration, and in order to solve this problem, an electric expansion valve with variable throttle amount and a variable capacity compressor have been used as the throttle mechanism to adjust the discharge temperature (for example, Patent Documents 1 and 2). reference).

  In addition, the liquid bypass mechanism that introduces the liquid refrigerant before the throttling mechanism into the compressor suction port suppresses an increase in the discharge temperature, thereby ensuring the reliability of the compressor.

  Against this background, recently, the adoption of HFC refrigerant as an alternative refrigerant for HCFC refrigerant has begun to be examined. This HFC-based refrigerant is effective in preventing global warming in addition to protecting the ozone layer. That is, it has a low GWP compared to conventional HCFC refrigerants (R410A, R407C, etc.). Therefore, the application of a mixed refrigerant containing R32 or R32, which is a kind of HFC-based refrigerant, is called out.

  When R32 is used in an air conditioner, the theoretical COP and heat transfer rate are higher and the pressure loss is smaller than the conventional refrigerants R22, R407C, and R410A, so that the actual cycle efficiency is increased. However, since the heat insulation index which is the thermophysical property of the refrigerant is larger than that of the conventional refrigerant, there is a characteristic that the discharge temperature of the compressor is higher by about 10 to 20 ° C. In particular, the discharge temperature further increases during an overload outside air temperature condition.

Japanese Patent No. 3465654 No. 2-333110

  However, in a refrigeration cycle apparatus using a constant speed compressor and a capillary tube that is a fixed throttle, the discharge temperature cannot be adjusted during an overload. Further, the liquid bypass mechanism requires a solenoid valve that opens when the discharge temperature becomes a certain level or more, which has been a factor in increasing costs.

  The present invention has been made in view of these points, and uses a constant speed compressor and a capillary tube, resulting in an overload state in which the discharge temperature of the compressor exceeds a predetermined reference value due to a change in environmental temperature or the like. In this case, it is an object of the present invention to provide a refrigeration cycle apparatus capable of ensuring the reliability of the compressor by suppressing an increase in the discharge temperature of the compressor at the time of overload at low cost.

  The present invention is a refrigeration cycle in which a constant speed compressor, a condenser, a throttle device, and an evaporator are connected in an annular shape, and the throttle device is a capillary tube, and heat is exchanged between the high pressure side refrigerant and the low pressure side refrigerant of the capillary tube. It is what.

  This suppresses an increase in the compressor discharge temperature without using a solenoid valve even when the discharge temperature of the compressor exceeds a predetermined reference value due to a change in environmental temperature or the like. Is possible.

  The present invention suppresses an increase in the discharge temperature of the compressor without using a solenoid valve even when the discharge temperature of the compressor exceeds a predetermined reference value due to a change in environmental temperature or the like. Therefore, a highly reliable refrigeration cycle can be achieved at low cost.

Refrigeration cycle diagram of the air conditioner in Embodiment 1 of the present invention PH diagram in the conventional refrigeration cycle PH diagram during overload operation in refrigeration cycle according to Embodiment 1 of the present invention Relationship between the amount of refrigerant flowing through the capillary and the degree of supercooling

  According to a first aspect of the present invention, in a refrigeration cycle in which a constant speed compressor, a condenser, a throttle device, and an evaporator are connected in an annular shape, the throttle device is a capillary tube, and between the high-pressure side refrigerant and the low-pressure side refrigerant of the capillary tube A refrigeration cycle system that has a heat exchange mechanism for exchanging heat with each other, can suppress the rise in the discharge temperature of the compressor at the time of overload, and can ensure the reliability of the compressor without using a solenoid valve. Can be provided.

  The second invention uses a refrigerant mixture mainly composed of R32 or R32 as a refrigerant in the first invention, and in addition to protecting the ozone layer, compared to conventional refrigerants (R410A, R407C, etc.) The low GWP contributes greatly to the prevention of global warming, while suppressing the rise in compressor discharge temperature during overload, which is a problem with mixed refrigerants mainly composed of R32 and R32. It is possible to provide a refrigeration cycle apparatus that ensures the performance.

  In the third invention, the mixed refrigerant mainly comprising R32 in the second invention is a mixed refrigerant of R32 and HFO1234yf.

  Thereby, like the second invention, while greatly contributing to the prevention of global warming, an increase in the discharge temperature of the compressor at the time of overload, which is a problem of the mixed refrigerant containing R32 as a main component, can be suppressed. It is possible to provide a refrigeration cycle apparatus that ensures the reliability.

  According to a fourth aspect of the present invention, in the first to third aspects of the invention, the capillary tube is provided with a cooling operation and a heating operation, so that the optimum throttle amount can be obtained for each of the cooling and heating, thereby improving efficiency. it can.

  According to a fifth invention, in the first to fourth inventions, the high-pressure side pipe and the low-pressure side pipe of the capillary tube are in close contact with each other to exchange heat, and the discharge temperature rise of the compressor at the time of overload is efficiently increased. Can be suppressed.

  The refrigeration cycle apparatus of the present invention will be described below. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a refrigeration cycle diagram when the refrigeration cycle apparatus of the present invention is used in an air conditioner. In addition, since the condenser 12 and the evaporator 14 are switched in the cooling operation and the heating operation, () is added to the reference numerals in the heating operation.

  The air conditioner of the present invention uses R32 or a mixed refrigerant mainly composed of R32, and the mixed refrigerant is a mixed refrigerant of R32 and HFO1234yf. Therefore, although effective in preventing global warming, there is a problem that the discharge temperature becomes higher than that of the conventional refrigerant when the outside air temperature condition is overloaded. This problem is solved by the configuration described below.

  That is, the air conditioner according to the present embodiment has, on the outdoor unit side, a constant speed compressor 1 that compresses refrigerant, a four-way valve 2 that switches a refrigerant circuit during cooling and heating operation, a condenser 12 during cooling operation, and a heating operation. An outdoor heat exchanger 3 that becomes an evaporator 14 and exchanges heat between the refrigerant and the outside air, and an outdoor fan 11 that promotes heat exchange between the refrigerant flowing in the outdoor heat exchanger 3 and the outside air are provided.

  And the heat exchange mechanism 8 which solves the discharge temperature rise problem of the said refrigerant | coolant is provided. The heat exchanging mechanism includes a cooling check valve 4 that opens during cooling operation and closes during heating operation, a heating capillary 5 that serves as a throttle device during heating, and a heating check valve 6 that opens during heating operation and closes during cooling operation. The high pressure side refrigerant pipe and the low pressure side refrigerant pipe in the vicinity of the cooling capillary 7 serving as the capillary 13 serving as a throttling device during cooling, the cooling capillary 7 or the heating capillary 5 serving as the capillary 13 serving as a throttling device during heating are brought into close contact with each other. Heat exchange.

  Furthermore, on the indoor unit side, an evaporator 14 is used in the cooling operation and a condenser 12 is used in the heating operation. The indoor heat exchanger 9 exchanges heat between the refrigerant and the room air, and the refrigerant and room air flowing through the indoor heat exchanger 9 are exchanged. An indoor fan 10 that promotes heat exchange is provided.

  The outdoor unit 22 is installed outdoors and the indoor unit 21 is installed indoors. The outdoor unit 22 and the indoor unit 21 are connected by a liquid side connection pipe 23 and a gas side connection pipe 24.

  Operation | movement is demonstrated about the air conditioner comprised in this way.

  First, during the cooling operation, the refrigerant compressed by the constant speed compressor 1 becomes a high-temperature and high-pressure refrigerant and passes through the four-way valve 2. Then, heat exchange with the outside air is promoted by the outdoor fan 11 to dissipate heat and become high-pressure liquid refrigerant, which is sent to the heat exchange mechanism 8 and sent to the cooling capillary 7 through the cooling check valve 4 that is opened during the cooling operation. It is done. At this time, the heating check valve 6 is closed.

  In the cooling capillary 7, the pressure is reduced to become a low-temperature and low-pressure two-phase refrigerant, the heat exchange mechanism 8 exchanges heat with the high-pressure side refrigerant, and the liquid is connected to the indoor heat exchanger 9 through the liquid connection pipe 23.

  The indoor air sucked by the indoor fan 10 exchanges heat with the refrigerant through the indoor heat exchanger 9, and the refrigerant absorbs the heat of the indoor air and evaporates to become a low-temperature gas refrigerant. At this time, the indoor air absorbed by the refrigerant has a reduced temperature and humidity, and is blown into the room by the indoor fan 10 to cool the room. Further, the gas refrigerant passes through the gas side connecting pipe 24 and enters the four-way valve 2 and returns to the constant speed compressor 1.

  During the heating operation, the refrigerant compressed by the constant speed compressor 1 passes through the four-way valve 2 and is sent to the gas connection pipe 24 as a high-temperature and high-pressure refrigerant. The indoor air sucked by the indoor fan 10 exchanges heat with the refrigerant through the indoor heat exchanger 9, and the refrigerant dissipates heat to the indoor air and condenses to become high-pressure liquid refrigerant. At this time, the indoor air absorbs the heat of the refrigerant and is blown into the room by the indoor fan 10 in a state where the temperature is raised, thereby heating the room. Thereafter, the refrigerant is sent to the heat exchanging mechanism 8 through the liquid connection pipe 23, and is sent to the heating capillary 5 through the heating check valve 6 opened during the heating operation. At this time, the check valve 4 at the time of cooling is closed.

  The pressure is reduced in the heating capillary 5 to become a low-temperature and low-pressure two-phase refrigerant. The heat exchange mechanism 8 exchanges heat with the high-pressure refrigerant, and is sent to the outdoor heat exchanger 3, and exchanges heat with the outside air by the outdoor fan 11. To evaporate and return to the constant speed compressor 1 via the four-way valve 2.

  In this way, the air conditioning operation is performed.

  Next, a conventional refrigeration cycle will be described with reference to FIG. FIG. 2 is a PH diagram of a prior art refrigeration cycle. In FIG. 2, the solid line represents the refrigeration cycle during normal operation, point A represents compressor suction, point B represents compressor discharge, point C represents a condenser outlet, and point D represents an evaporator inlet.

  Further, the broken line indicates the refrigeration cycle at the time of overload. The A ′ point indicates the compressor suction, the B ′ point indicates the compressor discharge, the C ′ point indicates the condenser outlet, and the D ′ point indicates the evaporator inlet. T1 indicates the temperature of the isotherm passing through the point B ', T2 is the temperature of the isotherm passing through the point B, and T1> T2.

  As shown in FIG. 2, when the normal operation becomes an overload operation due to a change in the environmental temperature or the like, the high pressure and the low pressure are increased, and the compressor discharge temperature is also increased. The discharge temperature of the compressor may exceed a predetermined reference value depending on conditions such as a rise above.

  However, this can be suppressed when the heat exchange mechanism 8 of the present invention is used. The operation of the heat exchange mechanism 8 will be described in detail with reference to FIG. FIG. 3 shows a PH diagram during overload operation, where the solid line indicates the refrigeration cycle of the present invention, and the broken line indicates the prior art refrigeration cycle.

  A 'point, B' point, C 'point and D' point indicate points of the prior art refrigeration cycle. A 'point indicates compressor suction, B' point indicates compressor discharge, C 'point indicates condenser outlet, and D' point indicates evaporator inlet.

  Moreover, A point, B point, C point, D point, E point, and F point have shown each point of the refrigerating cycle of this invention. Point A indicates compressor suction, point B indicates compressor discharge, point C indicates a condenser outlet, point D indicates an evaporator inlet, point E indicates a capillary inlet, and point F indicates a capillary outlet.

  During the cooling operation, the outlet of the outdoor heat exchanger 3 that is a condenser is the point C, the inlet of the cooling capillary 7 is the point E, the outlet is the point F, and the inlet of the indoor heat exchanger 9 that is the evaporator is the point D.

  The high-temperature and high-pressure liquid refrigerant that has passed through the outdoor heat exchanger 3 enters the heat exchange mechanism 8. On the other hand, the low-temperature and low-pressure two-phase refrigerant passes through the heat exchange mechanism 8 and exchanges heat with each other. Therefore, the high-temperature and high-pressure liquid refrigerant that has passed through the outdoor heat exchanger 3 exchanges heat by the heat exchange mechanism 8 to dissipate heat, so that the point C changes to the point E. The refrigerant at point E enters the cooling capillary 7 and adiabatically expands to become point F to become a low-temperature and low-pressure two-phase refrigerant. The heat exchange mechanism 8 exchanges heat and absorbs heat, so the point changes from point F to point D. In this way, heat exchange is performed by the heat exchange mechanism 8.

  At this time, the degree of supercooling of the refrigerant entering the cooling capillary 7 is larger than that of the conventional refrigeration cycle. The amount of refrigerant circulating through the cooling capillary 7 is approximately proportional to the pressure difference between the high pressure and the low pressure.

FIG. 4 shows the relationship between the amount of refrigerant flowing through the capillary tube 13 and the degree of supercooling. As shown in FIG. 4, when the pressure difference is constant, the refrigerant circulation amount changes greatly in a region where the degree of supercooling is small, and the refrigerant circulation amount becomes substantially constant when the degree of supercooling exceeds a certain level. In the prior art refrigeration cycle, the degree of supercooling at the inlet of the capillary tube 13 is small. Therefore, by increasing the degree of supercooling according to the refrigeration cycle of the present invention, the amount of refrigerant circulating through the capillary tube 13 is increased and the ratio is large. become.

  Therefore, in order to increase the circulation amount of the constant speed compressor 1, the low pressure is slightly increased to increase the suction density of the constant speed compressor 1, so that the discharge temperature of the constant speed compressor 1 is lowered. Further, at this time, since the low-pressure pressure increases, the input of the compressor is reduced and the efficiency of the refrigeration cycle is improved.

  T1 shown in FIG. 3 indicates the temperature of the isotherm passing through the point B ', T3 is the temperature of the isotherm passing through the point B, and T1> T3.

  Furthermore, since the degree of supercooling at the capillary inlet is large in normal operation in the refrigeration cycle of the prior art, even in the case of the refrigeration cycle of the present invention, the amount of refrigerant flowing through the capillary tends to increase slightly, but overload There is no big difference compared to driving.

  During the heating operation, the amount of refrigerant flowing through the capillaries increases during the overload operation due to the same operation, and the discharge temperature of the constant speed compressor 1 decreases, but a detailed description is omitted.

  In this way, in the refrigeration cycle in which the constant speed compressor 1, the condenser 12, the expansion device, and the evaporator 14 are connected in an annular shape, the expansion device is the capillary tube 13, and the high-pressure side refrigerant and the low-pressure side refrigerant of the capillary tube 13 are used. By adopting a configuration for exchanging heat, an overload state in which the discharge temperature of the constant speed compressor 1 exceeds a predetermined reference value due to a change in environmental temperature or the like at low cost without using a solenoid valve is performed. In addition, it is possible to ensure the reliability of the constant speed compressor 1 by suppressing an increase in the discharge temperature of the compressor. Mu

  According to the present invention, the compressor discharge temperature can be increased without using the solenoid valve even when the compressor discharge temperature exceeds a predetermined reference value due to a change in environmental temperature or the like. Since it can be suppressed, it can be a low-cost and highly reliable refrigeration cycle, and can be widely applied not only to household use but also to industrial refrigeration cycles.

1 Constant Speed Compressor 8 Heat Exchange Mechanism 5 Heating Capillary 7 Cooling Capillary 12 Condenser 13 Capillary Tube 14 Evaporator

Claims (5)

In a refrigeration cycle in which a constant speed compressor, a condenser, an expansion device, and an evaporator are connected in an annular shape, the expansion device is a capillary tube, and heat is exchanged between the high pressure side refrigerant and the low pressure side refrigerant of the capillary tube. A refrigeration cycle apparatus provided with an exchange mechanism. 2. The refrigeration cycle apparatus according to claim 1, wherein R32 or a mixed refrigerant mainly comprising R32 is used as the refrigerant. 3. The refrigeration cycle apparatus according to claim 2, wherein the mixed refrigerant containing R32 as a main component is a mixed refrigerant of R32 and HFO1234yf. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the capillary tube is provided with a cooling capillary and a heating capillary. The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein the high-pressure side pipe and the low-pressure side pipe of the capillary tube are in close contact with each other.

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