JP2009222348A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a risk of occurrence of liquid compression in a compressor, in a refrigerating device comprising a refrigerant circuit filled with a single refrigerant composed of a refrigerant represented by a molecular formula: C<SB>3</SB>H<SB>m</SB>F<SB>n</SB>(m=1-5, n=1-5, m+n=6), and having one double bond in a molecular structure, or a mixed refrigerant including the refrigerant. <P>SOLUTION: An air conditioner 1 comprises the refrigerant circuit 10 constituted by connecting the compressor 2, a heat source-side heat exchanger 4 as a radiator, an expanding mechanism 5, and a use-side heat exchanger 6 as an evaporator, and filled with HFO-1234yf(2,3,3,3-tetrafluoro-1-propene), and a superheating mechanism 8 disposed in the refrigerant circuit 10 and heating the refrigerant distributed from the use-side heat exchanger 6 to the compressor 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus including a refrigerant circuit.

  Conventionally, there are refrigeration apparatuses such as an air conditioner and a water heater. Such a refrigeration apparatus includes a compressor that compresses a refrigerant, a radiator that radiates heat of the refrigerant compressed by the compressor, an expansion mechanism that depressurizes the refrigerant radiated in the radiator, and a refrigerant that is depressurized in the expansion mechanism The refrigerant circuit comprised by connecting with the evaporator which evaporates is provided.

Then, as the refrigerant to be filled in such a refrigerant circuit, such as shown in Patent Document 1, molecular formula: C ₃ H _m F _n (where, m = 1~5, n = 1~5 and,, m + n = There is a refrigerant represented by 6) and having one double bond in the molecular structure. It is known that this refrigerant has excellent refrigeration performance such as a coefficient of performance and does not contribute to the destruction of the ozone layer.
JP-A-4-110388

  In addition, the refrigerant shown in the above-mentioned Patent Document 1 has a low global warming potential (GWP) other than the point that it has excellent refrigeration performance such as a coefficient of performance and does not contribute to the destruction of the ozone layer. Yes. For this reason, by using this refrigerant, it is possible to provide a refrigeration apparatus that has excellent refrigeration performance and is friendly to the global environment.

  However, this refrigerant has a characteristic that the slope of the isentropic line in the vicinity of the gas-phase line in the pressure-enthalpy diagram is steep compared to HCFC-22 and HFC-410A that are often used conventionally. In a refrigerant circuit filled with a single refrigerant composed of this refrigerant or a mixed refrigerant containing this refrigerant, the degree of superheat of the refrigerant discharged from the compressor tends to be small, and the refrigerant sucked into the compressor is in a wet state. Then, there is a problem that liquid compression occurs in the compressor and there is a high risk of damage.

An object of the present invention is represented by a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6), and 1 double bond is present in the molecular structure. In a refrigerating apparatus including a single refrigerant composed of individual refrigerants or a refrigerant circuit filled with a mixed refrigerant containing this refrigerant, the risk of liquid compression occurring in the compressor is reduced.

A refrigeration apparatus according to a first invention includes a compressor that compresses a refrigerant, a radiator that radiates heat of the refrigerant compressed by the compressor, an expansion mechanism that depressurizes the refrigerant radiated by the radiator, and a pressure reduction in the expansion mechanism. Is connected to an evaporator for evaporating the generated refrigerant, and has a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6). And a refrigerant circuit filled with a single refrigerant consisting of a refrigerant having one double bond in the molecular structure or a mixed refrigerant containing this refrigerant, and compressed from the evaporator provided in the refrigerant circuit And an overheating mechanism for heating the refrigerant sent to the machine.

In this refrigeration apparatus, molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6) and one double bond in the molecular structure Compared to HCFC-22 and HFC-410A, which are conventionally used, a single refrigerant composed of a refrigerant having a single refrigerant or a mixed refrigerant containing this refrigerant is isentropic curve near the gas phase line of the pressure-enthalpy diagram In consideration of the characteristic that the inclination of the refrigerant is steep, the refrigerant sucked into the compressor becomes wet by heating the refrigerant sent from the evaporator to the compressor by the overheating mechanism provided in the refrigerant circuit. (That is, the refrigerant sucked into the compressor is in an overheated state), the risk of liquid compression occurring in the compressor can be reduced.

  A refrigerating apparatus according to a second aspect is the refrigerating apparatus according to the first aspect, wherein the overheating mechanism heats the refrigerant sent from the evaporator to the compressor by the refrigerant sent from the radiator to the expansion mechanism. It is an exchanger.

  In this refrigeration apparatus, the first internal heat exchanger that heats the refrigerant sent from the evaporator to the compressor using the relatively high-temperature refrigerant sent from the radiator to the expansion mechanism is used as the overheating mechanism. An external cooling source is not necessary, and the refrigerant sucked into the compressor can be reliably prevented from becoming wet.

  A refrigerating apparatus according to a third aspect is the refrigerating apparatus according to the first aspect, wherein the overheating mechanism branches the refrigerant sent from the radiator to the evaporator and joins the refrigerant sent from the evaporator to the compressor. A return pipe and a second internal heat exchanger that heats the refrigerant flowing through the suction return pipe by the refrigerant sent from the radiator to the expansion mechanism.

  In this refrigeration apparatus, a second internal heat exchanger that heats the refrigerant flowing through the suction return pipe using a relatively high-temperature refrigerant sent from the radiator to the expansion mechanism is used as the overheating mechanism, and this second internal heat exchange is performed. Since the refrigerant flowing through the suction return pipe heated by the evaporator is joined to the refrigerant sent from the evaporator to the compressor, the refrigerant sent from the evaporator to the compressor is heated. And the refrigerant sucked into the compressor can be reliably prevented from becoming wet.

  The refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to any one of the first to third aspects, wherein an accumulator for storing refrigerant sucked into the compressor is provided as a container for storing excess refrigerant in the refrigerant circuit. ing.

  In this refrigeration apparatus, it is possible to reliably prevent the refrigerant sucked into the compressor from becoming wet by storing excess refrigerant in the accumulator.

  The refrigeration apparatus according to a fifth aspect of the present invention is the refrigeration apparatus according to the third aspect of the present invention, further comprising a receiver for storing the refrigerant radiated by the radiator as a container for storing excess refrigerant in the refrigerant circuit.

  In this refrigeration apparatus, the amount of surplus refrigerant that accumulates in the accumulator can be reduced, so that it is possible to more reliably prevent wet refrigerant from being sucked into the compressor.

The refrigeration apparatus according to a sixth aspect of the present invention is the refrigeration apparatus according to any one of the first to third aspects of the present invention, wherein the refrigerant filled in the refrigerant circuit has a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6), and is a mixed refrigerant containing a refrigerant having one double bond in the molecular structure, and as a container for storing excess refrigerant in the refrigerant circuit, A receiver for storing the refrigerant that has radiated heat in the radiator is provided without providing an accumulator for storing the refrigerant sucked into the compressor.

The refrigerant filled in the refrigerant circuit is represented by the molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6), and double in the molecular structure. In the case of a mixed refrigerant including a refrigerant having one bond, if an accumulator that stores the refrigerant sucked into the compressor is provided, the composition of the mixed refrigerant is likely to change, so that a desired refrigeration capacity can be obtained. There is a risk of being lost.

  However, in this refrigeration apparatus, since an accumulator is not provided, only a receiver that is located at a high pressure in the refrigeration cycle and hardly changes in composition of the mixed refrigerant is provided to accumulate excess refrigerant in the refrigerant circuit. The composition change of the mixed refrigerant that is highly likely to occur when the is provided is suppressed, and a desired refrigeration capacity can be obtained.

  A refrigeration apparatus according to a seventh invention is the refrigeration apparatus according to any one of the first to fifth inventions, wherein the refrigerant filled in the refrigerant circuit is from 2,3,3,3-tetrafluoro-1-propene. It is a single refrigerant.

  A refrigeration apparatus according to an eighth invention is the refrigeration apparatus according to any one of the first to sixth inventions, wherein the refrigerant charged in the refrigerant circuit is 2,3,3,3-tetrafluoro-1-propene. It is a mixed refrigerant with difluoromethane.

  A refrigeration apparatus according to a ninth invention is the refrigeration apparatus according to any one of the first to sixth inventions, wherein the refrigerant charged in the refrigerant circuit is 2,3,3,3-tetrafluoro-1-propene. It is a mixed refrigerant with pentafluoroethane.

  As described above, according to the present invention, the following effects can be obtained.

  In the first and seventh to ninth inventions, the risk of liquid compression occurring in the compressor can be reduced.

  In the second or third invention, an external cooling source is not required, and the refrigerant sucked into the compressor can be reliably prevented from becoming wet.

  In 4th invention, it can prevent reliably that the refrigerant | coolant suck | inhaled by a compressor will be in a wet state by accumulating an excess refrigerant | coolant in an accumulator.

  In the fifth aspect of the invention, since the amount of excess refrigerant that accumulates in the accumulator can be reduced, it is possible to more reliably prevent the wet refrigerant from being sucked into the compressor.

  In the sixth aspect of the invention, the composition change of the mixed refrigerant that is likely to occur when the accumulator is provided is suppressed, and a desired refrigeration capacity can be obtained.

  Hereinafter, an embodiment of a refrigeration apparatus according to the present invention will be described based on the drawings.

(1) Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of an air conditioner 1 as an embodiment of a refrigeration apparatus according to the present invention. The air conditioner 1 has a refrigerant circuit 10 configured to be capable of cooling operation, and uses a single refrigerant made of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene). And it is an apparatus which performs a refrigerating cycle. Here, the chemical formula of HFO-1234yf is represented by CF ₃ —CF═CH ₂ .

  The refrigerant circuit 10 of the air conditioner 1 mainly includes a compressor 2, a heat source side heat exchanger 4, an expansion mechanism 5, a use side heat exchanger 6, and a superheat mechanism 8.

  The compressor 2 is a mechanism for compressing the refrigerant, and is a hermetic compressor driven by the drive motor 2a in the present embodiment. In the present embodiment, only one compressor 2 is provided. However, the present invention is not limited to this, and two or more compressors may be connected in parallel depending on the number of connected units used. .

  The heat source side heat exchanger 4 is a heat exchanger that functions as a refrigerant radiator. One end of the heat source side heat exchanger 4 is connected to the compressor 2, and the other end is connected to the expansion mechanism 5 via a first internal heat exchanger 11 (described later) constituting the overheating mechanism 8. . Although not shown here, the heat source side heat exchanger 4 is supplied with water and air as a cooling source for exchanging heat with the refrigerant flowing through the heat source side heat exchanger 4.

  The expansion mechanism 5 is a mechanism that depressurizes the refrigerant sent from the heat source side heat exchanger 4 as a radiator to the use side heat exchanger 6 as an evaporator, and an electric expansion valve is used in this embodiment. . One end of the expansion mechanism 5 is connected to the heat source side heat exchanger 4 via a first internal heat exchanger 11 (described later) constituting the superheating mechanism 8, and the other end is connected to the use side heat exchanger 6. Yes. Further, in the present embodiment, the expansion mechanism 5 reaches the low pressure in the refrigeration cycle before sending the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator to the use side heat exchanger 6 as an evaporator. Reduce pressure.

  The use side heat exchanger 6 is a heat exchanger that functions as a refrigerant evaporator. The use side heat exchanger 6 has one end connected to the expansion mechanism 5 and the other end connected to the compressor 2. Although not shown here, the use side heat exchanger 6 is supplied with water and air as a heat source for exchanging heat with the refrigerant flowing through the use side heat exchanger 6.

  The superheat mechanism 8 is a mechanism for heating the refrigerant sent from the use side heat exchanger 6 as an evaporator to the compressor 2, and in this embodiment, the heat source side heat exchanger 4 as a radiator is connected to the expansion mechanism 5. It is the 1st internal heat exchanger 11 which heats the refrigerant sent from use side heat exchanger 6 to compressor 2 with the sent refrigerant. In the present embodiment, the first internal heat exchanger 11 is opposed to the refrigerant sent from the heat source side heat exchanger 4 as a radiator to the expansion mechanism 5 and the refrigerant sent from the use side heat exchanger 6 to the compressor 2. It has a flow path that flows like this.

  In addition, the air conditioner 1 includes a control unit that controls the operation of each part of the air conditioner 1 such as the compressor 2 and the expansion mechanism 5 that is not illustrated here.

(2) Operation | movement of an air conditioning apparatus Next, operation | movement of the air conditioning apparatus 1 of this embodiment is demonstrated using FIG.1 and FIG.2. Here, FIG. 2 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the cooling operation. The operation control in the following cooling operation is performed by the above-described control unit (not shown). In the following description, “high pressure” means high pressure in the refrigeration cycle (that is, pressure at points B, B ′, C, and F in FIG. 2), and “low pressure” means low pressure in the refrigeration cycle ( That is, the pressure at points A, D, D ′, and E in FIG.

  During the cooling operation, the opening degree of the expansion mechanism 5 is adjusted. In the state of the refrigerant circuit 10, the low-pressure refrigerant (see point A in FIGS. 1 and 2) is sucked into the compressor 2 and is discharged after being compressed to a high pressure in the refrigeration cycle (FIGS. 1 and 2). Point B). The high-pressure refrigerant discharged from the compressor 2 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator, and is cooled by exchanging heat with water or air as a cooling source ( (See point C in FIGS. 1 and 2). Then, the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator is sent to the first internal heat exchanger 11 constituting the superheating mechanism 8 and from the use side heat exchanger 6 as an evaporator. The refrigerant is cooled by exchanging heat with the refrigerant sent to the compressor 2 (see point F in FIGS. 1 and 2). The high-pressure refrigerant cooled in the first internal heat exchanger 11 constituting the superheating mechanism 8 is depressurized by the expansion mechanism 5 to become a low-pressure gas-liquid two-phase refrigerant, and functions as a refrigerant evaporator. It is sent to the use side heat exchanger 6 (see point D in FIGS. 1 and 2). Then, the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 as an evaporator is heated by exchanging heat with water or air as a heating source to evaporate ( (See point E in FIGS. 1 and 2). The low-pressure refrigerant heated and evaporated in the use side heat exchanger 6 as the evaporator expands from the heat source side heat exchanger 4 as the radiator in the first internal heat exchanger 11 constituting the superheating mechanism 8. Heat exchange is performed with the refrigerant sent to the mechanism 5 so that the refrigerant is heated and overheated, and then sucked into the compressor 2 (see point A in FIGS. 1 and 2). In this way, the cooling operation is performed.

Thus, in the air conditioning apparatus 1 of the present embodiment, the molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6) and the molecule Since a single refrigerant composed of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene), which is a kind of refrigerant having one double bond in the structure, is used, the refrigeration performance is excellent. It is possible to provide an environmentally friendly air conditioner.

  Moreover, in the air conditioner 1 of the present embodiment, the HFO-1234yf has an isentropic line near the gas phase line of the pressure-enthalpy diagram compared to the HCFC-22 and HFC-410A that are often used conventionally. In consideration of the characteristic that the inclination is steep, the refrigerant sent from the use side heat exchanger 6 as the evaporator to the compressor 2 is heated by the superheating mechanism 8 provided in the refrigerant circuit 10 (see FIG. 2). Since the refrigerant sucked into the compressor 2 is prevented from becoming wet (that is, the refrigerant sucked into the compressor 2 is overheated). The risk of liquid compression occurring in the compressor 2 can be reduced.

  This will be described in detail with reference to FIGS. 3 is a pressure-enthalpy diagram illustrating a refrigeration cycle using HCFC-22, and FIG. 4 is a pressure-enthalpy diagram illustrating a refrigeration cycle using HFC-410A. . 2 to 4, the horizontal axis is displayed with the same enthalpy width, and the vertical axis is displayed with a saturation pressure width corresponding to −10 ° C. to 50 ° C.

  First, in the refrigerant circuit 10 of the present embodiment, when the superheating mechanism 8 (here, the first internal heat exchanger 11) is omitted, when HFO-1234yf is used as the refrigerant, the point E → the point B ′ in FIG. A refrigeration cycle consisting of a stroke of point C → point D ′ → point E (that is, a refrigeration cycle without a stroke of point C → point F and a stroke of point E → point A by the overheating mechanism 8) is performed. . Here, if the conditions of this refrigeration cycle are a saturated gas state where the evaporation temperature is 0 ° C., the condensation temperature is 40 ° C., the refrigerant at point E is 0 ° C., and the compressor efficiency is 75%, the compressor 2 discharges from the compressor 2. The degree of superheat of the high-pressure refrigerant that is generated is 5 ° C. On the other hand, when HCFC-22 is used as the refrigerant under the same refrigeration cycle conditions, the degree of superheat of the high-pressure refrigerant discharged from the compressor 2 is 29 ° C., and HFC-410A is used as the refrigerant. When used, the degree of superheat of the high-pressure refrigerant discharged from the compressor 2 is 25 ° C. The difference in superheat degree of the high-pressure refrigerant discharged from the compressor 2 is that the slope of the isentropic line near the gas phase line of the pressure-enthalpy diagram of HFO-1234yf is compared with HCFC-22 and HFC-410A. Due to the steep and steep characteristics, when using HFO-1234yf, the compression stroke line of the refrigeration cycle in the pressure-enthalpy diagram (compared to using HCFC-22 or HFC-410A) ( 2 to 4) (see point E → point B ′) and the gas phase line are reduced, so that when the refrigerant sucked into the compressor 2 becomes wet, liquid compression occurs in the compressor 2 and damage occurs. It turns out that there is a high risk of doing.

  Therefore, in the air conditioning apparatus 1 of the present embodiment, in consideration of such characteristics of HFO-1234yf, as described above, the refrigerant sent from the use side heat exchanger 6 as an evaporator to the compressor 2 is heated. The refrigerant circuit 10 is provided with the overheating mechanism 8 that prevents the refrigerant sucked into the compressor 2 from becoming wet (that is, the refrigerant sucked into the compressor 2 is overheated). Therefore, the risk of liquid compression occurring in the compressor 2 can be reduced.

  Moreover, in the air conditioning apparatus 1 of this embodiment, the use side heat exchange as an evaporator using the comparatively high-temperature refrigerant | coolant sent to the expansion mechanism 5 from the heat source side heat exchanger 4 as a radiator as the overheating mechanism 8 is used. Since the first internal heat exchanger 11 that heats the refrigerant sent from the compressor 6 to the compressor 2 is employed, an external cooling source is not necessary, and the refrigerant sucked into the compressor 2 is in a wet state. Can be surely prevented.

  Moreover, the first internal heat exchanger 11 constituting the overheating mechanism 8 includes a refrigerant sent from the heat source side heat exchanger 4 as a radiator to the expansion mechanism 5 and a refrigerant sent from the use side heat exchanger 6 to the compressor 2. Therefore, the refrigerant sent to the expansion mechanism 5 from the heat source side heat exchanger 4 as a radiator in the first internal heat exchanger 11 and the utilization side heat as an evaporator The temperature difference from the refrigerant sent from the exchanger 6 to the compressor 2 is reduced, and thereby the degree of superheat of the refrigerant sent from the use side heat exchanger 6 to the compressor 2 can be increased.

  In this embodiment, a single refrigerant made of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene) is used as the refrigerant, but instead of this, HFO-1234yf is used. Similar to HCFC-22 and HFC-410A, which are often used in the past, other refrigerants that have a characteristic that the slope of the isentropic line near the gas-phase line in the pressure-enthalpy diagram is steep are used. May be.

Such a refrigerant has a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6), and a double bond is present in the molecular structure. A single refrigerant consisting of one refrigerant can be used. For example, HFO-1225ye (1,2,3,3,3-pentafluoro-1-propene, chemical formula: CF ₃ —CF═CHF), HFO-1234ze (1,3,3,3-tetrafluoro-1- Propene, chemical formula: CF ₃ —CH═CHF), HFO-1234ye (1,2,3,3-tetrafluoro-1-propene, chemical formula: CHF ₂ —CF═CHF), HFO-1234zf (3, 3, 3 - trifluoro-1-propene, chemical _{formula: CF 3 -CH = CH 2)} , 1,2,2- trifluoro-1-propene (chemical _{formula: CH 3 -CF = CF 2)} , 2- fluoro - propene (chemical formula : it is possible to use a CH ₃ -CF = CH ₂₎ and the like.

  Moreover, you may use the mixed refrigerant | coolant containing the above-mentioned refrigerant | coolant. For example, there is a mixed refrigerant of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene) and HFC-32 (difluoromethane). Here, as a composition of the mixed refrigerant, the ratio of HFO-1234yf is 50% by mass to 94% by mass and the ratio of HFC-32 is 6% by mass to 30% by mass, preferably HFO-1234yf. The proportion is 77% by mass or more and 87% by mass or less, and the proportion of HFC-32 is preferably 13% by mass or more and 23% by mass or less. More preferably, the proportion of HFO-1234yf is 77% by mass or more and 79% by mass or less. Is preferably 21% by mass or more and 23% by mass or less (for example, a mixed refrigerant of 78% by mass of HFO-1234yf and 22% by mass of HFC-32). Further, there is a mixed refrigerant of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene) and HFC-125 (pentafluoroethane). Here, the composition of the mixed refrigerant is such that the ratio of HFO-1234yf is 90% by mass or less and the ratio of HFC-125 is 10% by mass or more, preferably, the ratio of HFO-1234yf is 80% by mass or more and 90% by mass. %, The ratio of HFC-125 is preferably 10% by mass or more and 20% by mass or less. In addition, other HFC refrigerants such as HFC-134 (1,1,2,2-tetrafluoroethane), HFC-134a (1,1,1,2-tetrafluoroethane), HFC-143a (1, 1,1-trifluoroethane), HFC-152a (1,1-difluoroethane), HFC-161 (fluoroethane), HFC-227ea (1,1,1,2,3,3,3-heptafluoropropane) HFC-236ea (1,1,1,2,3,3-hexafluoropropane), HFC-236fa (1,1,1,3,3,3-heptafluoropropane), HFC-365mfc (1,1 , 1,3,3-pentafluorobutane) or the like may be used. In addition, other refrigerants such as hydrocarbons, not HFC refrigerants, such as methane, ethane, propane, propene, butane, isobutane, pentane, 2-methylbutane, cyclopentane, dimethyl ether, bis-trifluoromethyl-sulfide, A mixed refrigerant with carbon dioxide, helium or the like may be used.

Further, refrigerants represented by molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5 and m + n = 6) and having one double bond in the molecular structure Or a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6), and a double bond in the molecular structure And other refrigerants such as the above-mentioned HFC refrigerants and hydrocarbons, the molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6), and a mixed refrigerant composed of three or more components including at least one refrigerant having one double bond in the molecular structure may be used. For example, there is a mixed refrigerant of HFO-1234yf, HFC-32, and HFC-125 (for example, a mixed refrigerant of 52% by weight of HFO-1234yf, 23% by mass of HFC-32, and 25% by weight of HFC-125). .

Also in these mixed refrigerants, molecular formulas such as HFO-1234yf: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6) are present in the molecular structure. Contains a refrigerant having one double bond, and the slope of the isentropic curve near the gas-phase line in the pressure-enthalpy diagram is steeper than that of HCFC-22 and HFC-410A, which are often used in the past. Therefore, as described above, the air conditioner is excellent in refrigerating performance and is friendly to the global environment, and is sent from the use side heat exchanger 6 as an evaporator to the compressor 2. By providing the refrigerant circuit 10 with the overheating mechanism 8 that heats the refrigerant, the refrigerant sucked into the compressor 2 can be prevented from becoming wet, and the risk of liquid compression occurring in the compressor 2 can be reduced.

(3) Modification 1
In the air conditioning apparatus 1 according to the above-described embodiment, the molecular formula is represented by C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6), and in the molecular structure. In the refrigerant circuit 10 filled with a single refrigerant consisting of a refrigerant having one double bond or a mixed refrigerant containing this refrigerant, the refrigerant sent from the use side heat exchanger 6 as an evaporator to the compressor 2 Overheating mechanism 8 (here, the first internal heat that heats the refrigerant sent from the use side heat exchanger 6 to the compressor 2 by the refrigerant sent from the heat source side heat exchanger 4 as a radiator to the expansion mechanism 5) By providing the exchanger 11) in the refrigerant circuit 10, the refrigerant sucked into the compressor 2 is prevented from becoming wet, and the possibility of liquid compression occurring in the compressor 2 is reduced. In addition to this, the cold sucked into the compressor 2 There To reliably prevented from becoming wet state, an accumulator 17 for storing surplus refrigerant caused by fluctuations in the operating conditions in the refrigerant circuit 10 may be provided in the refrigerant circuit 10.

  Thereby, in the air conditioning apparatus 1 of this modification, the effect in the above-described embodiment can be obtained, and the possibility of liquid compression occurring in the compressor 2 can be further reduced.

(4) Modification 2
In the air conditioner 1 according to the above-described modification 1, the refrigerant sucked into the compressor 2 is sent to the compressor 2 from the use side heat exchanger 6 serving as an evaporator in order to prevent the refrigerant from getting wet. Overheating mechanism 8 that heats the refrigerant (here, a first internal portion that heats the refrigerant sent from the use side heat exchanger 6 to the compressor 2 by the refrigerant sent from the heat source side heat exchanger 4 as a radiator to the expansion mechanism 5) Although the accumulator 17 is provided together with the heat exchanger 11), as shown in FIG. 6, in addition to this, the amount of surplus refrigerant accumulated in the accumulator 17 is reduced and the refrigerant sucked into the compressor 2 is moistened. In order to further prevent the state from entering, the refrigerant circuit 10 may be further provided with a receiver 18 for storing the refrigerant radiated in the heat source side heat exchanger 4 as a radiator.

  Thereby, in the air conditioning apparatus 1 of this modification, the effect in the above-mentioned modification 1 is obtained, and the possibility that liquid compression occurs in the compressor 2 can be further reduced.

(5) Modification 3
In the air conditioner 1 according to the second modification described above, the refrigerant sucked into the compressor 2 is sent to the compressor 2 from the use side heat exchanger 6 serving as an evaporator in order to prevent the refrigerant from getting wet. Overheating mechanism 8 that heats the refrigerant (here, a first internal portion that heats the refrigerant sent from the use side heat exchanger 6 to the compressor 2 by the refrigerant sent from the heat source side heat exchanger 4 as a radiator to the expansion mechanism 5) Although the accumulator 17 and the receiver 18 are provided together with the heat exchanger 11), the refrigerant filled in the refrigerant circuit 10 is a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5 and m + n = 6), and in the case of a mixed refrigerant containing a refrigerant having one double bond in the molecular structure, an accumulator 17 for collecting refrigerant sucked into the compressor 2 is provided. This mixed refrigerant set Since the change is likely to occur, thereby, it may become impossible to obtain the desired refrigeration capacity.

  Therefore, in the air conditioner 1 according to this modification, as shown in FIG. 7, only the receiver 18 that is located at a high pressure in the refrigeration cycle and hardly changes in the composition of the mixed refrigerant is provided without providing the accumulator 17. The excess refrigerant in the refrigerant circuit 10 is accumulated.

  Thereby, in the air conditioning apparatus 1 of this modification, while having the effect in the above-mentioned embodiment, the composition change of the mixed refrigerant that is likely to occur when the accumulator 17 is provided is suppressed, and a desired refrigeration capacity is achieved. Obtainable.

(6) Modification 4
In the above-mentioned embodiment and its modifications 1-3, the heat source side heat exchanger 4 as a radiator is used as the overheating mechanism 8 for heating the refrigerant sent from the use side heat exchanger 6 as an evaporator to the compressor 2. A first internal heat exchanger 11 is used which heats the refrigerant sent from the use side heat exchanger 6 as an evaporator to the compressor 2 using a relatively high temperature refrigerant sent to the expansion mechanism 5 (see FIG. 1, 5-7), but is not limited to this, and any mechanism that heats the refrigerant sent from the use side heat exchanger 6 to the compressor 2 can be used.

  For example, in the refrigerant circuit 10 (see FIG. 1) of the air-conditioning apparatus 1 of the above-described embodiment, as shown in FIG. 8, the superheat mechanism 8 is replaced with the first internal heat exchanger 11 as a radiator. A suction return pipe 12 for branching the refrigerant sent from the heat source side heat exchanger 4 to the use side heat exchanger 6 as an evaporator and joining the refrigerant sent from the use side heat exchanger 6 to the compressor 2; The refrigerant circuit 110 may include a second internal heat exchanger 13 that heats the refrigerant flowing through the suction return pipe 12 by the refrigerant sent from the heat exchanger 4 to the expansion mechanism 5.

  Here, the suction return pipe 12 branches the refrigerant sent from the heat source side heat exchanger 4 as a radiator to the expansion mechanism 5 and joins the refrigerant sent from the use side heat exchanger 6 to the compressor 2. It is. In the present modification, the suction return pipe 12 is configured such that the refrigerant sent from the heat source side heat exchanger 4 serving as a radiator to the expansion mechanism 5 undergoes heat exchange in the second internal heat exchanger 13 and then the heat source side heat exchanger 4. Is provided so as to branch the refrigerant sent to the expansion mechanism 5. More specifically, the suction return pipe 12 branches the refrigerant from a position downstream of the second internal heat exchanger 13 (that is, between the second internal heat exchanger 13 and the expansion mechanism 5) and uses the refrigerant. It is provided so as to merge with the refrigerant sent from the heat exchanger 6 to the compressor 2. The suction return pipe 12 is provided with a suction return valve 12a capable of opening degree control. The suction return valve 12a is an electric expansion valve in this modification.

  The second internal heat exchanger 13 is a refrigerant that flows through the suction return pipe 12 by the refrigerant sent from the heat source side heat exchanger 4 to the expansion mechanism 5 (more specifically, in the vicinity of the low pressure in the refrigeration cycle in the suction return pipe 12). It is a heat exchanger that heats the refrigerant after being depressurized until. In the present modification, the second internal heat exchanger 13 has a position upstream of the position where the suction return pipe 12 is branched (that is, the heat source side heat exchanger 4 as a radiator and the suction return pipe 12 are branched. The refrigerant is provided so as to exchange heat between the refrigerant flowing between the refrigerant and the refrigerant flowing through the suction return pipe 12, and has a flow path through which both refrigerants face each other. For this reason, the refrigerant cooled in the heat source side heat exchanger 4 serving as a radiator is branched into the suction return pipe 12 after exchanging heat with the refrigerant flowing through the suction return pipe 12 in the second internal heat exchanger 13. Will be.

  Furthermore, various sensors are provided in the air conditioning apparatus 1 of the present modification. Specifically, the second internal heat exchanger 13 detects the temperature of the refrigerant at the outlet of the second internal heat exchanger 13 on the suction return pipe 12 side at the outlet of the second internal heat exchanger 13 on the suction return pipe 12 side. An outlet temperature sensor 14 is provided, and a suction pressure sensor 15 that detects the pressure of the refrigerant sucked into the compressor 2 is provided on the suction side of the compressor 2.

  Next, operation | movement of the air conditioning apparatus 1 of this modification is demonstrated using FIG.8 and FIG.9. Here, FIG. 9 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the cooling operation in the present modification. The operation control in the following cooling operation is performed by the same control unit (not shown) as in the above-described embodiment. In the following description, “high pressure” means high pressure in the refrigeration cycle (that is, pressure at points B, B ′, C, and G in FIG. 9), and “low pressure” means low pressure in the refrigeration cycle ( That is, the pressures at points A, D, D ′, E, H, and I in FIG.

  During the cooling operation, the opening degree of the expansion mechanism 5 is adjusted. The opening degree of the suction return valve 12a is also adjusted. More specifically, in this modification, the suction return valve 12a is adjusted in opening degree so that the degree of superheat of the refrigerant at the outlet on the suction return pipe 12 side of the second internal heat exchanger 13 becomes a target value. So-called superheat control is performed. In this modification, the superheat degree of the refrigerant at the outlet on the suction return pipe 12 side of the second internal heat exchanger 13 is calculated by converting the low pressure detected by the suction pressure sensor 15 into the saturation temperature, and the second internal heat exchange outlet temperature. It is obtained by subtracting the saturation temperature value of the refrigerant from the refrigerant temperature detected by the sensor 14. Although not adopted in the present modification, a temperature sensor is provided at the inlet of the second internal heat exchanger 13 on the suction return pipe 12 side, and the refrigerant temperature detected by this temperature sensor is used as the second internal heat exchange outlet. By subtracting from the refrigerant temperature detected by the temperature sensor 14, the degree of superheat of the refrigerant at the outlet on the suction return pipe 12 side of the second internal heat exchanger 13 may be obtained. Further, the adjustment of the opening degree of the suction return valve 12a is not limited to the superheat degree control, and for example, it may be opened only by a predetermined opening degree according to the refrigerant circulation amount in the refrigerant circuit 110 or the like. In the state of the refrigerant circuit 110, the low-pressure refrigerant (see point A in FIGS. 8 and 9) is sucked into the compressor 2 and discharged after being compressed to a high pressure in the refrigeration cycle (FIGS. 8 and 9). Point B). The high-pressure refrigerant discharged from the compressor 2 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator, and is cooled by exchanging heat with water or air as a cooling source ( (See point C in FIGS. 8 and 9). Then, the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator is sent to the second internal heat exchanger 13 constituting the superheating mechanism 8, and the suction return pipe 12 constituting the superheating mechanism 8 is passed through the suction return pipe 12. The refrigerant is cooled by exchanging heat with the flowing refrigerant (see point G in FIGS. 8 and 9). A part of the high-pressure refrigerant cooled in the second internal heat exchanger 13 is branched to the suction return pipe 12. Then, the refrigerant flowing through the suction return pipe 12 is depressurized to near low pressure in the suction return valve 12a, and then sent to the second internal heat exchanger 13 (see point H in FIGS. 8 and 9), as described above. In addition, after heat is exchanged with the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator and heated, the superheat state according to the target value in the superheat degree control of the suction return valve 12a is reached ( 8 (see point I in FIG. 9), the refrigerant is sent from the use side heat exchanger 6 serving as an evaporator to the refrigerant 2. The high-pressure refrigerant cooled in the second internal heat exchanger 13 is decompressed by the expansion mechanism 5 to become a low-pressure gas-liquid two-phase refrigerant and functions as a refrigerant evaporator. (See point D in FIGS. 8 and 9). Then, the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 as an evaporator is heated by exchanging heat with water or air as a heating source to evaporate ( (See point E in FIGS. 8 and 9). The low-pressure refrigerant heated and evaporated in the use-side heat exchanger 6 as the evaporator is heated by joining the refrigerant flowing through the suction return pipe 12 that has been overheated in the second internal heat exchanger 13. After being overheated, it is sucked into the compressor 2 (see point A in FIGS. 8 and 9). In this way, the cooling operation is performed.

  As described above, in the air conditioner 1 of the present modification, the overheating mechanism 8 flows through the suction return pipe 12 using a relatively high-temperature refrigerant sent from the heat source side heat exchanger 4 as a radiator to the expansion mechanism 5. A second internal heat exchanger that heats the refrigerant is employed, a suction return pipe 12 and a second internal heat exchanger 13 are employed, and the refrigerant flowing through the suction return pipe 12 heated by the second internal heat exchanger 13 is The above-described implementation is that the refrigerant sent from the use side heat exchanger 6 to the compressor 2 is heated by joining the refrigerant sent from the use side heat exchanger 6 to the compressor 2 as an evaporator. The operation of the refrigeration cycle is different from the case where the superheating mechanism 8 including the first internal heat exchanger 11 in the embodiment is adopted. However, also in the air conditioner 1 of this modification, HFO-1234yf is an isentropic line near the gas phase line of the pressure-enthalpy diagram compared to HCFC-22 and HFC-410A that are often used conventionally. In consideration of the characteristic that the inclination of the refrigerant is steep, the refrigerant sent from the use side heat exchanger 6 as the evaporator to the compressor 2 is heated by the superheating mechanism 8 provided in the refrigerant circuit 110 (FIG. 9). Point E and point A), the refrigerant sucked into the compressor 2 is prevented from becoming wet (that is, the refrigerant sucked into the compressor 2 is overheated). About is the same as that of the above-mentioned embodiment, Thereby, the effect similar to the above-mentioned embodiment can be acquired.

  Moreover, the second internal heat exchanger 13 constituting the overheating mechanism 8 flows so that the refrigerant sent from the heat source side heat exchanger 4 as a radiator to the expansion mechanism 5 and the refrigerant flowing through the suction return pipe 12 face each other. Since it has a flow path, the temperature difference between the refrigerant sent to the expansion mechanism 5 from the heat source side heat exchanger 4 as a radiator in the second internal heat exchanger 13 and the refrigerant flowing through the suction return pipe 12 becomes small. Thus, the degree of superheat of the refrigerant flowing through the suction return pipe 12 can be increased, and as a result, the refrigerant flowing through the suction return pipe 12 is sent from the use side heat exchanger 6 as an evaporator to the compressor 2. It is also possible to increase the degree of superheat of the refrigerant after it has been joined.

  In this modification, the suction return pipe 12 is provided so as to branch the refrigerant from a position downstream of the internal heat exchanger 13 (that is, between the second internal heat exchanger 13 and the expansion mechanism 5). However, the present invention is not limited to this, and the suction return pipe 12 is positioned upstream of the internal heat exchanger 13 (that is, between the heat source side heat exchanger 4 and the second internal heat exchanger 13 as a radiator). It may be provided so as to branch the refrigerant. However, as described above, the suction return pipe 12 is provided so as to branch the refrigerant from a position downstream of the internal heat exchanger 13 (that is, between the second internal heat exchanger 13 and the expansion mechanism 5). However, the flow rate of the refrigerant flowing through the suction return pipe 12 increases, and the flow rate of the refrigerant that merges with the refrigerant sent from the use-side heat exchanger 6 to the compressor 2 through the suction return pipe 12 increases. This is advantageous for the purpose of increasing the degree of superheat of the refrigerant after the refrigerant flowing through 12 is joined to the refrigerant sent from the use side heat exchanger 6 as an evaporator to the compressor 2.

Also in this modified example, as in the above-described embodiment, instead of a single refrigerant made of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene), the molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6), and a single refrigerant comprising a refrigerant having one double bond in the molecular structure It may be used or a mixed refrigerant containing these refrigerants may be used.

  Further, in this modified example, as shown in FIG. 10, in addition to this, in order to reliably prevent the refrigerant sucked into the compressor 2 from becoming wet as shown in FIG. The refrigerant circuit 110 may be provided with an accumulator 17 for accumulating surplus refrigerant caused by fluctuations in operating conditions in the refrigerant circuit 110.

  Also in the present modification, as shown in FIG. 11, in addition to the accumulator 17, the receiver 18 that stores the heat dissipated in the heat source side heat exchanger 4 as a radiator is also provided as in the above-described modification 2. You may make it provide in the refrigerant circuit 110 further.

Further, in the present modified example, as in the above-described modified example 3, the refrigerant charged in the refrigerant circuit 110 has a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, And m + n = 6), and in the case of a mixed refrigerant including a refrigerant having one double bond in the molecular structure, the accumulator 17 is not provided as shown in FIG. Only the receiver 18 which is located at a high pressure in the cycle and hardly changes the composition of the mixed refrigerant may be provided so as to accumulate excess refrigerant in the refrigerant circuit 110.

(7) Modification 5
In the above-described embodiment and Modifications 1 to 3, the overheating mechanism 8 (specifically, the first internal heat exchanger 11) is provided in the cooling-only refrigerant circuit 10 (see FIGS. 1 and 5 to 7). Furthermore, although the accumulator 17 and the receiver 18 are provided, this configuration may be employed in a refrigerant circuit capable of switching between a cooling operation and a heating operation.

  For example, as shown in FIG. 13, in the refrigerant circuit 10 (see FIG. 1) provided with the superheating mechanism 8 including the first internal heat exchanger 11, switching for enabling switching between cooling operation and heating operation. It can be set as the refrigerant circuit 210 provided with the bridge circuit 16 for making the flow direction of the refrigerant | coolant to the mechanism 3 and the 1st internal heat exchanger 11 constant.

  Here, the switching mechanism 3 is a mechanism for switching the direction of the flow of the refrigerant in the refrigerant circuit 210, and during the cooling operation, the heat source side heat exchanger 4 is used as a radiator for the refrigerant discharged from the compressor 2. In addition, the discharge side of the compressor 2 and one end of the heat source side heat exchanger 4 are connected and compressed so that the use side heat exchanger 6 functions as an evaporator of the refrigerant cooled in the heat source side heat exchanger 4. The suction side of the machine 2 and the use side heat exchanger 6 are connected (see the solid line of the switching mechanism 3 in FIG. 13, hereinafter, the state of the switching mechanism 3 is referred to as “cooling operation state”). In order to function the use side heat exchanger 6 as a radiator for the refrigerant discharged from the compressor 2 and the heat source side heat exchanger 4 as an evaporator for the refrigerant cooled in the use side heat exchanger 6, compression is performed. Connecting the discharge side of the machine 2 and the use side heat exchanger 6 In addition, it is possible to connect the suction side of the compressor 2 and one end of the heat source side heat exchanger 4 (refer to the broken line of the switching mechanism 3 in FIG. 13; hereinafter, the state of the switching mechanism 3 is referred to as “heating operation”. State ”). In this modification, the switching mechanism 3 is a four-way switching valve connected to the suction side of the compressor 2, the discharge side of the compressor 2, the heat source side heat exchanger 4, and the use side heat exchanger 6. The switching mechanism 3 is not limited to a four-way switching valve, and is configured to have a function of switching the refrigerant flow direction as described above, for example, by combining a plurality of electromagnetic valves. There may be.

  The bridge circuit 16 is provided between the heat source side heat exchanger 4 and the use side heat exchanger 6, and includes an inlet pipe 19a connected to the inlet of the first internal heat exchanger 11, and the first It is connected to an outlet pipe 19b connected to the outlet of the internal heat exchanger 11. The bridge circuit 16 has four check valves 16a, 16b, 16c, and 16d in this modification. The inlet check valve 16a is a check valve that allows only the refrigerant to flow from the heat source side heat exchanger 4 to the inlet pipe 19a. The inlet check valve 16b is a check valve that allows only the refrigerant to flow from the use side heat exchanger 6 to the inlet pipe 19a. That is, the inlet check valves 16a and 16b have a function of circulating the refrigerant from one of the heat source side heat exchanger 4 and the use side heat exchanger 6 to the inlet pipe 19a. The outlet check valve 16c is a check valve that allows only the refrigerant to flow from the outlet pipe 19b to the use-side heat exchanger 6. The outlet check valve 16d is a check valve that allows only the refrigerant to flow from the outlet pipe 19b to the heat source side heat exchanger 4. That is, the outlet check valves 16c and 16d have a function of circulating the refrigerant from the outlet pipe 19b to the other of the heat source side heat exchanger 4 and the use side heat exchanger 6.

  The expansion mechanism 5 is provided in the outlet pipe 19b. The first internal heat exchanger 11 is provided so as to heat the refrigerant flowing through the inlet pipe 19a by the refrigerant sent from the switching mechanism 3 to the suction side of the compressor 2.

  Thus, in the refrigerant circuit 210 of this modification, the compressor 2, the heat source side heat exchanger 4, the first internal heat exchanger 11, the expansion mechanism 5, and the use side heat exchanger are switched by the switching mechanism 3 and the bridge circuit 16. A cooling operation state in which the refrigerant is circulated in the order of 6, and a heating operation state in which the refrigerant is circulated in the order of the compressor 2, the use side heat exchanger 6, the first internal heat exchanger 11, the expansion mechanism 5, and the heat source side heat exchanger 4. And can be switched.

  Next, operation | movement of the air conditioning apparatus 1 of this modification is demonstrated using FIG.13 and FIG.2. Here, the refrigeration cycle during the cooling operation in the present modification will be described with reference to FIG. 2, and the refrigeration cycle during the heating operation will be described by replacing point C and point D in FIG. It shall be. The operation control in the following cooling operation and heating operation is performed by the same control unit (not shown) as in the above-described embodiment.

  During the cooling operation, the switching mechanism 3 is in a cooling operation state indicated by a solid line in FIG. The opening degree of the expansion mechanism 5 is adjusted. In the state of the refrigerant circuit 210, low-pressure refrigerant (see point A in FIGS. 13 and 2) is sucked into the compressor 2 and discharged after being compressed to high pressure in the refrigeration cycle (FIGS. 13 and 2). Point B). Then, the high-pressure refrigerant discharged from the compressor 2 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator via the switching mechanism 3, and water and air as the cooling source and heat It is exchanged and cooled (see point C in FIGS. 13 and 2). The high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator flows into the inlet pipe 19a through the inlet check valve 16a of the bridge circuit 16, and constitutes the overheating mechanism 8. 11 and is cooled by exchanging heat with the refrigerant sent from the use side heat exchanger 6 as an evaporator to the compressor 2 (see point F in FIGS. 13 and 2). Then, the high-pressure refrigerant cooled in the first internal heat exchanger 11 constituting the superheating mechanism 8 is sent to the outlet pipe 19b and decompressed by the expansion mechanism 5 to become a low-pressure gas-liquid two-phase refrigerant. The refrigerant is sent to the use side heat exchanger 6 functioning as a refrigerant evaporator through the outlet check valve 16c of the bridge circuit 16 (see point D in FIGS. 13 and 2). Then, the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 as an evaporator is heated by exchanging heat with water or air as a heating source to evaporate ( (See point E in FIGS. 13 and 2). Then, the low-pressure refrigerant heated and evaporated in the use side heat exchanger 6 as the evaporator is sent to the first internal heat exchanger 11 constituting the superheating mechanism 8 via the switching mechanism 3, and the first In the internal heat exchanger 11, heat is exchanged with the refrigerant sent from the heat source side heat exchanger 4 as a radiator to the expansion mechanism 5 to be overheated and then sucked into the compressor 2 (see FIG. 13, see point A in FIG. In this way, the cooling operation is performed.

  During the heating operation, the switching mechanism 3 is in a heating operation state indicated by a solid line in FIG. The opening degree of the expansion mechanism 5 is adjusted. In the state of the refrigerant circuit 210, low-pressure refrigerant (see point A in FIGS. 13 and 2) is sucked into the compressor 2 and discharged after being compressed to high pressure in the refrigeration cycle (FIGS. 13 and 2). Point B). Then, the high-pressure refrigerant discharged from the compressor 2 is sent via the switching mechanism 3 to the use side heat exchanger 6 that functions as a refrigerant radiator, and water, air, and heat as a cooling source. Cooling is performed after replacement (refer to point C in FIG. 13 and FIG. 2 as point D). Then, the high-pressure refrigerant cooled in the use-side heat exchanger 6 as a radiator flows into the inlet pipe 19a through the inlet check valve 16b of the bridge circuit 16, and constitutes the overheating mechanism 8. 11 and is cooled by exchanging heat with the refrigerant sent from the heat source side heat exchanger 4 as an evaporator to the compressor 2 (see point F in FIGS. 13 and 2). The high-pressure refrigerant cooled in the first internal heat exchanger 11 constituting the superheating mechanism 8 is sent to the outlet pipe 19b and decompressed by the expansion mechanism 5, and becomes a low-pressure gas-liquid two-phase refrigerant. It is sent to the heat source side heat exchanger 4 functioning as a refrigerant evaporator through the outlet check valve 16d of the circuit 16 (refer to point D in FIGS. 13 and 2 as point C). Then, the low-pressure gas-liquid two-phase refrigerant sent to the heat source side heat exchanger 4 serving as the evaporator is heated by performing heat exchange with water and air serving as the heating source, and evaporates ( (See point E in FIGS. 13 and 2). Then, the low-pressure refrigerant heated and evaporated in the heat source side heat exchanger 4 as the evaporator is sent to the first internal heat exchanger 11 constituting the superheating mechanism 8 via the switching mechanism 3, and the first In the internal heat exchanger 11, heat is exchanged with the refrigerant sent from the use side heat exchanger 6 as a radiator to the expansion mechanism 5 to be heated to an overheated state, and then sucked into the compressor 2 (FIG. 13, see point A in FIG. In this way, the heating operation is performed.

  Thus, in the air-conditioning apparatus 1 of the present modification, in the cooling operation, from the use side heat exchanger 6 as an evaporator by the overheating mechanism 8 including the first internal heat exchanger 11 provided in the refrigerant circuit 210. By heating the refrigerant sent to the compressor 2 (see point E and point A in FIG. 2), the refrigerant sucked into the compressor 2 can be prevented from becoming wet, and also in heating operation By heating the refrigerant sent to the compressor 2 from the heat source side heat exchanger 4 as an evaporator by the superheating mechanism 8 provided in the refrigerant circuit 210 (see points E and A in FIG. 2), the compressor 2 Therefore, it is possible to reduce the possibility of liquid compression occurring in the compressor 2 in both the cooling operation and the heating operation.

Also in this modified example, as in the above-described embodiment, instead of a single refrigerant made of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene), the molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6), and a single refrigerant comprising a refrigerant having one double bond in the molecular structure It may be used or a mixed refrigerant containing these refrigerants may be used.

  In addition, in this modified example, as shown in FIG. 14, in addition to the above-described modified example 1, in addition to this, in order to reliably prevent the refrigerant sucked into the compressor 2 from becoming wet, The refrigerant circuit 210 may be provided with an accumulator 17 for accumulating surplus refrigerant generated due to fluctuations in operating conditions in the refrigerant circuit 210.

  Also in this modified example, as in the above-described modified example 2, as shown in FIG. 15, in addition to the accumulator 17, heat is radiated in the heat source side heat exchanger 4 or the utilization side heat exchanger 6 as a radiator. The refrigerant circuit 210 may be further provided with a receiver 18 for storing the refrigerant.

Further, in the present modified example, as in the above-described modified example 3, the refrigerant charged in the refrigerant circuit 210 has a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, And m + n = 6), and in the case of a mixed refrigerant including a refrigerant having one double bond in the molecular structure, the accumulator 17 is not provided as shown in FIG. Only the receiver 18 that is located at a high pressure in the cycle and hardly changes the composition of the mixed refrigerant may be provided so that the excess refrigerant in the refrigerant circuit 210 is accumulated.

(8) Modification 6
In the above-described modification 4, the overheating mechanism 8 (specifically, the suction return pipe 12 and the second internal heat exchanger 13) is provided in the cooling-only refrigerant circuit 110 (see FIGS. 8 and 10 to 12). Furthermore, although the accumulator 17 and the receiver 18 are provided, this configuration may be employed in a refrigerant circuit capable of switching between a cooling operation and a heating operation.

  For example, as shown in FIG. 17, in the refrigerant circuit 110 (see FIG. 8) provided with the superheating mechanism 8 including the suction return pipe 12 and the second internal heat exchanger 13, the cooling operation and the heating operation can be switched. And the refrigerant circuit 310 provided with the bridge circuit 16 for making the flow direction of the refrigerant to the second internal heat exchanger 13 constant.

  Here, since the switching mechanism 3 is the same as the switching mechanism 3 of the above-mentioned modification 5, description is abbreviate | omitted here. Further, the bridge circuit 16 is configured such that the inlet pipe 19a and the outlet pipe 19b are connected to the inlet and outlet of the second internal heat exchanger 13 instead of the inlet and outlet of the first internal heat exchanger 11. Since this is the same as the bridge circuit 16 of the above-described modified example 5, the description thereof is omitted here. The expansion mechanism 5 and the suction return pipe 12 are provided in the outlet pipe 19b. The second internal heat exchanger 13 is provided so as to heat the refrigerant flowing through the inlet pipe 19a by the refrigerant sent from the switching mechanism 3 to the suction side of the compressor 2.

  Thus, in the refrigerant circuit 310 of this modification, the compressor 2, the heat source side heat exchanger 4, the second internal heat exchanger 13, the expansion mechanism 5, and the use side heat exchanger are switched by the switching mechanism 3 and the bridge circuit 16. 6 is a cooling operation state in which the refrigerant is circulated in order, and a heating operation state in which the refrigerant is circulated in the order of the compressor 2, the use side heat exchanger 6, the second internal heat exchanger 13, the expansion mechanism 5, and the heat source side heat exchanger 4. And can be switched.

  Next, operation | movement of the air conditioning apparatus 1 of this modification is demonstrated using FIG.17 and FIG.9. Here, the refrigeration cycle during the cooling operation in this modification will be described with reference to FIG. 9, and the refrigeration cycle during the heating operation will be described by replacing point C and point D in FIG. It shall be. The operation control in the following cooling operation and heating operation is performed by the same control unit (not shown) as in the above-described embodiment.

  During the cooling operation, the switching mechanism 3 is in a cooling operation state indicated by a solid line in FIG. The opening degree of the expansion mechanism 5 is adjusted. In addition, the opening adjustment of the suction return valve 12a is performed in the same manner as in the fourth modification. In the state of the refrigerant circuit 310, the low-pressure refrigerant (see point A in FIGS. 17 and 9) is sucked into the compressor 2 and discharged after being compressed to a high pressure in the refrigeration cycle (FIGS. 17 and 9). Point B). Then, the high-pressure refrigerant discharged from the compressor 2 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator via the switching mechanism 3, and water and air as the cooling source and heat It is exchanged and cooled (see point C in FIGS. 17 and 9). The high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator flows into the inlet pipe 19 a through the inlet check valve 16 a of the bridge circuit 16, and constitutes the overheating mechanism 8. 13 is cooled by exchanging heat with the refrigerant flowing through the suction return pipe 12 constituting the superheating mechanism 8 (see point G in FIGS. 17 and 9). Then, the high-pressure refrigerant cooled in the second internal heat exchanger 13 is sent to the outlet pipe 19 b and a part thereof is branched to the suction return pipe 12. The refrigerant flowing through the suction return pipe 12 is depressurized to near low pressure in the suction return valve 12a, and then sent to the second internal heat exchanger 13 (see point H in FIGS. 17 and 9), as described above. In addition, after heat is exchanged with the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator and heated, the superheat state according to the target value in the superheat degree control of the suction return valve 12a is reached ( 17 and FIG. 9 (see point I), the refrigerant is sent to the compressor 2 from the use side heat exchanger 6 as an evaporator. Then, the high-pressure refrigerant cooled in the second internal heat exchanger 13 is decompressed by the expansion mechanism 5 to become a low-pressure gas-liquid two-phase refrigerant, and the refrigerant is discharged through the outlet check valve 16c of the bridge circuit 16. It is sent to the use side heat exchanger 6 functioning as an evaporator (see point D in FIGS. 17 and 9). Then, the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 as an evaporator is heated by exchanging heat with water or air as a heating source to evaporate ( (See point E in FIGS. 17 and 9). The low-pressure refrigerant heated and evaporated in the use-side heat exchanger 6 as the evaporator is heated by joining the refrigerant flowing through the suction return pipe 12 that has been overheated in the second internal heat exchanger 13. After being overheated, it is sucked into the compressor 2 (see point A in FIGS. 17 and 9). In this way, the cooling operation is performed.

  During the heating operation, the switching mechanism 3 is in a heating operation state indicated by a solid line in FIG. The opening degree of the expansion mechanism 5 is adjusted. Further, the opening degree of the suction return valve 12a is adjusted in the same manner as in the cooling operation. In the state of the refrigerant circuit 310, the low-pressure refrigerant (see point A in FIGS. 17 and 9) is sucked into the compressor 2 and discharged after being compressed to a high pressure in the refrigeration cycle (FIGS. 17 and 9). Point B). Then, the high-pressure refrigerant discharged from the compressor 2 is sent via the switching mechanism 3 to the use side heat exchanger 6 that functions as a refrigerant radiator, and water, air, and heat as a cooling source. Cooling is performed after replacement (refer to point C in FIGS. 17 and 9 as point D). Then, the high-pressure refrigerant cooled in the use side heat exchanger 6 as a radiator flows into the inlet pipe 19 a through the inlet check valve 16 b of the bridge circuit 16, and constitutes the overheating mechanism 8. 13 is cooled by exchanging heat with the refrigerant flowing through the suction return pipe 12 constituting the superheating mechanism 8 (see point G in FIGS. 17 and 9). Then, the high-pressure refrigerant cooled in the second internal heat exchanger 13 is sent to the outlet pipe 19 b and a part thereof is branched to the suction return pipe 12. The refrigerant flowing through the suction return pipe 12 is depressurized to near low pressure in the suction return valve 12a, and then sent to the second internal heat exchanger 13 (see point H in FIGS. 17 and 9), as described above. In addition, after being heated by exchanging heat with the high-pressure refrigerant cooled in the use side heat exchanger 6 as a radiator, the superheat state corresponding to the target value in the superheat degree control of the suction return valve 12a is reached ( 17 and FIG. 9 (see point I), the refrigerant is sent from the heat source side heat exchanger 4 as an evaporator to the compressor 2. Then, the high-pressure refrigerant cooled in the second internal heat exchanger 13 is reduced in pressure by the expansion mechanism 5 to become a low-pressure gas-liquid two-phase refrigerant, and passes through the outlet check valve 16d of the bridge circuit 16 to It is sent to the heat source side heat exchanger 4 functioning as an evaporator (refer to point D in FIGS. 17 and 9 as point C). Then, the low-pressure gas-liquid two-phase refrigerant sent to the heat source side heat exchanger 4 serving as the evaporator is heated by performing heat exchange with water and air serving as the heating source, and evaporates ( (See point E in FIGS. 17 and 9). The low-pressure refrigerant heated and evaporated in the heat source side heat exchanger 4 as the evaporator is heated by joining the refrigerant flowing through the suction return pipe 12 that has been overheated in the second internal heat exchanger 13. After being overheated, it is sucked into the compressor 2 (see point A in FIGS. 17 and 9). In this way, the heating operation is performed.

  As described above, in the air conditioner 1 of the present modification, in the cooling operation, the use side as the evaporator is provided by the overheating mechanism 8 including the suction return pipe 12 and the second internal heat exchanger 13 provided in the refrigerant circuit 310. By heating the refrigerant sent from the heat exchanger 6 to the compressor 2 (see point E and point A in FIG. 9), it is possible to prevent the refrigerant sucked into the compressor 2 from becoming wet. Even in the heating operation, the refrigerant sent from the heat source side heat exchanger 4 as an evaporator to the compressor 2 is heated by the superheating mechanism 8 provided in the refrigerant circuit 310 (see points E and A in FIG. 9). ) Since the refrigerant sucked into the compressor 2 can be prevented from becoming wet, it is possible to reduce the possibility of liquid compression occurring in the compressor 2 in both the cooling operation and the heating operation.

Also in this modification, as in Modification 4 described above, instead of a single refrigerant made of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene), the molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6) and a single refrigerant comprising a refrigerant having one double bond in the molecular structure Or a mixed refrigerant containing these refrigerants may be used.

  Further, in this modified example, as shown in FIG. 18, in addition to this, in order to reliably prevent the refrigerant sucked into the compressor 2 from becoming wet as shown in FIG. An accumulator 17 that accumulates surplus refrigerant generated due to fluctuations in operating conditions in the refrigerant circuit 310 may be provided in the refrigerant circuit 310.

  Also in this modified example, as in the above modified example 4, as shown in FIG. 19, in addition to the accumulator 17, heat is radiated in the heat source side heat exchanger 4 or the utilization side heat exchanger 6 as a radiator. The refrigerant circuit 310 may be further provided with a receiver 18 for storing the refrigerant.

Further, in the present modified example, as in the above-described modified example 4, the refrigerant charged in the refrigerant circuit 310 has a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, And m + n = 6), and in the case of a mixed refrigerant including a refrigerant having one double bond in the molecular structure, the accumulator 17 is not provided as shown in FIG. Only the receiver 18 which is located at a high pressure in the cycle and hardly changes the composition of the mixed refrigerant may be provided so as to store the excess refrigerant in the refrigerant circuit 310.

(9) Modification 7
In the refrigerant circuit 210 (see FIGS. 13 to 16) in the above-described modified example 5, in the configuration having one use side heat exchanger 6, the cooling operation for setting the switching mechanism 3 to the cooling operation state and the heating operation for the switching mechanism 3. In any heating operation to be performed, the refrigerant sent from the use side heat exchanger 6 as the evaporator or the heat source side heat exchanger 4 to the compressor 2 is cooled by the superheating mechanism 8 including the first internal heat exchanger 11. Heating prevents the refrigerant sucked into the compressor 2 from becoming wet, thereby reducing the risk of liquid compression in the compressor 2. You may apply to the refrigerant circuit which can perform cooling and heating according to an air-conditioning load.

  For example, as shown in FIG. 21, in the refrigerant circuit 210 (see FIG. 13) provided with the superheating mechanism 8 composed of the first internal heat exchanger 11, a plurality (here, three) connected in parallel to each other. The use side heat exchanger 6 is provided, the use side expansion mechanism 5b is provided so as to correspond to each use side heat exchanger 6, and the expansion mechanism 5 provided in the outlet pipe 19b is further deleted. A refrigerant circuit 410 in which a heat source side expansion mechanism 5 a is provided between the side heat exchanger 4 and the bridge circuit 16 can be provided. In this modification, the heat source side expansion mechanism 5a and the use side expansion mechanism 5b are electric expansion valves.

  In the refrigerant circuit 410 of the present modification, the compressor 2, the heat source side heat exchanger 4, the heat source side expansion mechanism 5a, the first internal heat exchanger 11, and the use side expansion mechanism 5b are switched by the switching mechanism 3 and the bridge circuit 16. The cooling operation state in which the refrigerant is circulated in the order of the use side heat exchanger 6, the compressor 2, the use side heat exchanger 6, the use side expansion mechanism 5b, the first internal heat exchanger 11, the heat source side expansion mechanism 5a, the heat source It is comprised so that the heating operation state which circulates a refrigerant | coolant in order of the side heat exchanger 4 can be switched.

  Next, operation | movement of the air conditioning apparatus 1 of this modification is demonstrated using FIG.21 and FIG.22. Here, FIG. 22 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the cooling operation in the present modification. In addition, the refrigeration cycle during the heating operation will be described by replacing point C and point D in FIG. The operation control in the following cooling operation and heating operation is performed by the same control unit (not shown) as in the above-described embodiment. In the following description, “high pressure” means high pressure in the refrigeration cycle (that is, pressure at points B, B ′, C, F, and J in FIG. 22), and “low pressure” means in the refrigeration cycle. It means low pressure (that is, pressure at points A, D, and E in FIG. 22).

  During the cooling operation, the switching mechanism 3 is in the cooling operation state indicated by the solid line in FIG. The opening degree of the expansion mechanism 5 is adjusted. In the state of the refrigerant circuit 410, the low-pressure refrigerant (see point A in FIGS. 21 and 22) is sucked into the compressor 2 and discharged after being compressed to a high pressure in the refrigeration cycle (FIGS. 21 and 22). Point B). Then, the high-pressure refrigerant discharged from the compressor 2 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator via the switching mechanism 3, and water and air as the cooling source and heat It is exchanged and cooled (see point C in FIGS. 21 and 22). The high-pressure refrigerant cooled in the heat-source-side heat exchanger 4 as a radiator is decompressed to near the saturation pressure by the heat-source-side expansion mechanism 5a (see point J in FIGS. 21 and 22), and then the bridge circuit 16 The refrigerant flows into the inlet pipe 19a through the inlet check valve 16a, is sent to the first internal heat exchanger 11 constituting the superheat mechanism 8, and is sent from the use side heat exchanger 6 as an evaporator to the compressor 2. And is cooled by exchanging heat (see point F in FIGS. 21 and 22). The high-pressure refrigerant cooled in the first internal heat exchanger 11 constituting the superheating mechanism 8 is sent to the use-side expansion mechanism 5b through the outlet pipe 19b and the outlet check valve 16c of the bridge circuit 16, and used. The refrigerant is depressurized by the side expansion mechanism 5b to become a low-pressure gas-liquid two-phase refrigerant, and is sent to the use-side heat exchanger 6 that functions as a refrigerant evaporator (see point D in FIGS. 21 and 22). Then, the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 as an evaporator is heated by exchanging heat with water or air as a heating source to evaporate ( (See point E in FIGS. 21 and 22). Then, the low-pressure refrigerant heated and evaporated in the use side heat exchanger 6 as the evaporator is sent to the first internal heat exchanger 11 constituting the superheating mechanism 8 via the switching mechanism 3, and the first In the internal heat exchanger 11, heat is exchanged with the refrigerant sent from the heat source side heat exchanger 4 as a radiator to the utilization side expansion mechanism 5 b to be heated and overheated, and then sucked into the compressor 2. (See point A in FIGS. 21 and 22). In this way, the cooling operation is performed.

  During the heating operation, the switching mechanism 3 is in a heating operation state indicated by a solid line in FIG. The opening degree of the expansion mechanism 5 is adjusted. In the state of the refrigerant circuit 410, the low-pressure refrigerant (see point A in FIGS. 21 and 22) is sucked into the compressor 2 and discharged after being compressed to a high pressure in the refrigeration cycle (FIGS. 21 and 22). Point B). Then, the high-pressure refrigerant discharged from the compressor 2 is sent via the switching mechanism 3 to the use side heat exchanger 6 that functions as a refrigerant radiator, and water, air, and heat as a cooling source. Cooling is performed after replacement (refer to point C in FIGS. 21 and 22 as point D). The high-pressure refrigerant cooled in the use-side heat exchanger 6 as a radiator is reduced to near the saturation pressure by the use-side expansion mechanism 5b (see point J in FIGS. 21 and 22), and then the bridge circuit 16 The refrigerant flows into the inlet pipe 19a through the inlet check valve 16b, is sent to the first internal heat exchanger 11 constituting the superheating mechanism 8, and is sent to the compressor 2 from the heat source side heat exchanger 4 as an evaporator. And is cooled by exchanging heat (see point F in FIGS. 21 and 22). Then, the high-pressure refrigerant cooled in the first internal heat exchanger 11 constituting the superheating mechanism 8 is sent to the heat source side expansion mechanism 5a through the outlet pipe 19b and the outlet check valve 16d of the bridge circuit 16, and is supplied to the heat source. The refrigerant is decompressed by the side expansion mechanism 5a to become a low-pressure gas-liquid two-phase refrigerant, and is sent to the heat source side heat exchanger 4 that functions as a refrigerant evaporator (replaces point D in FIG. 21 and FIG. 22 with point C). See). Then, the low-pressure gas-liquid two-phase refrigerant sent to the heat source side heat exchanger 4 serving as the evaporator is heated by performing heat exchange with water and air serving as the heating source, and evaporates ( (See point E in FIGS. 21 and 22). Then, the low-pressure refrigerant heated and evaporated in the heat source side heat exchanger 4 as the evaporator is sent to the first internal heat exchanger 11 constituting the superheating mechanism 8 via the switching mechanism 3, and the first In the internal heat exchanger 11, heat is exchanged with the refrigerant sent from the use side heat exchanger 6 as a radiator to the expansion mechanism 5 to be heated to an overheated state, and then sucked into the compressor 2 (FIG. 21, see point A in FIG. In this way, the heating operation is performed.

  As described above, also in the air conditioner 1 of the present modified example, in the cooling operation, in the cooling operation, the evaporation is performed by the superheating mechanism 8 including the first internal heat exchanger 11 provided in the refrigerant circuit 410. By heating the refrigerant sent from the use side heat exchanger 6 as a compressor to the compressor 2 (see point E and point A in FIG. 22), the refrigerant sucked into the compressor 2 is prevented from becoming wet. In the heating operation, the refrigerant sent from the heat source side heat exchanger 4 as the evaporator to the compressor 2 is heated by the superheating mechanism 8 provided in the refrigerant circuit 410 (point of FIG. 22). E, see point A), and the refrigerant sucked into the compressor 2 can be prevented from becoming wet, so that the possibility of liquid compression occurring in the compressor 2 is reduced in both the cooling operation and the heating operation. be able to.

Also in this modified example, as in Modified Example 5 above, instead of a single refrigerant composed of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene), the molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6) and a single refrigerant comprising a refrigerant having one double bond in the molecular structure Or a mixed refrigerant containing these refrigerants may be used.

  Further, in this modified example as well as the above-described modified example 5, in addition to this, in order to reliably prevent the refrigerant sucked into the compressor 2 from becoming wet, as shown in FIG. The refrigerant circuit 410 may be provided with an accumulator 17 for accumulating surplus refrigerant caused by fluctuations in operating conditions in the refrigerant circuit 410.

  Also in this modified example, as in the above modified example 5, as shown in FIG. 24, in addition to the accumulator 17, heat is radiated in the heat source side heat exchanger 4 or the utilization side heat exchanger 6 as a radiator. The refrigerant circuit 410 may be further provided with a receiver 18 that stores the refrigerant.

Further, in the present modified example as well, as in the above-described modified example 5, the refrigerant charged in the refrigerant circuit 410 has a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, And m + n = 6), and in the case of a mixed refrigerant containing a refrigerant having one double bond in the molecular structure, the accumulator 17 is not provided as shown in FIG. Only the receiver 18 that is located at a high pressure in the cycle and hardly changes the composition of the mixed refrigerant may be provided so as to store the excess refrigerant in the refrigerant circuit 410.

(10) Modification 8
In the refrigerant circuit 310 (see FIGS. 17 to 20) in the above-described modified example 6, in the configuration having one use side heat exchanger 6, the cooling operation for switching the switching mechanism 3 to the cooling operation state and the heating operation for the switching mechanism 3 are performed. In any heating operation to be performed, the superheater mechanism 8 including the suction return pipe 12 and the second internal heat exchanger 13 causes the compressor 2 from the use side heat exchanger 6 or the heat source side heat exchanger 4 as an evaporator. By heating the refrigerant sent to the compressor 2, the refrigerant sucked into the compressor 2 is prevented from becoming wet, thereby reducing the possibility that liquid compression occurs in the compressor 2. You may apply to the refrigerant circuit which can perform the air_conditioning | cooling and heating according to the air-conditioning load of several air-conditioning space.

  For example, as shown in FIG. 26, in the refrigerant circuit 310 (see FIG. 17) provided with the superheating mechanism 8 including the suction return pipe 12 and the second internal heat exchanger 13, a plurality (here, Then, the three use side heat exchangers 6 are provided, the use side expansion mechanism 5b is provided so as to correspond to each use side heat exchanger 6, and the expansion mechanism 5 provided in the outlet pipe 19b is further provided. It can delete and it can be set as the refrigerant circuit 510 which provided the heat source side expansion mechanism 5a between the heat source side heat exchanger 4 and the bridge circuit 16. FIG. In this modification, the heat source side expansion mechanism 5a and the use side expansion mechanism 5b are electric expansion valves.

  And in the refrigerant circuit 510 of this modification, the switching mechanism 3 and the bridge circuit 16 allow the compressor 2, the heat source side heat exchanger 4, the heat source side expansion mechanism 5a, the second internal heat exchanger 13, and the use side expansion mechanism 5b. The cooling operation state in which the refrigerant is circulated in the order of the use side heat exchanger 6, the compressor 2, the use side heat exchanger 6, the use side expansion mechanism 5b, the second internal heat exchanger 13, the heat source side expansion mechanism 5a, the heat source It is comprised so that the heating operation state which circulates a refrigerant | coolant in order of the side heat exchanger 4 can be switched.

  Next, operation | movement of the air conditioning apparatus 1 of this modification is demonstrated using FIG.26 and FIG.27. Here, FIG. 27 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the cooling operation in the present modification. In addition, the refrigeration cycle during the heating operation will be described by replacing point C and point D in FIG. The operation control in the following cooling operation and heating operation is performed by the same control unit (not shown) as in the above-described embodiment. In the following description, “high pressure” means high pressure in the refrigeration cycle (that is, pressure at points B, B ′, C, F, and J in FIG. 27), and “low pressure” means in the refrigeration cycle. It means low pressure (that is, pressure at points A, D, and E in FIG. 27).

  During the cooling operation, the switching mechanism 3 is in a cooling operation state indicated by a solid line in FIG. The opening degree of the expansion mechanism 5 is adjusted. Further, the opening degree of the suction return valve 12a is adjusted in the same manner as in the sixth modification. In the state of the refrigerant circuit 510, low-pressure refrigerant (see point A in FIGS. 26 and 27) is sucked into the compressor 2 and discharged after being compressed to high pressure in the refrigeration cycle (FIGS. 26 and 27). Point B). Then, the high-pressure refrigerant discharged from the compressor 2 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator via the switching mechanism 3, and water and air as the cooling source and heat It is exchanged and cooled (see point C in FIGS. 26 and 27). The high-pressure refrigerant cooled in the heat source side heat exchanger 4 serving as a radiator is decompressed to near saturation pressure by the heat source side expansion mechanism 5a (see point J in FIGS. 26 and 27), and then the bridge circuit 16 Flows into the inlet pipe 19a through the inlet check valve 16a and is sent to the second internal heat exchanger 13 constituting the superheating mechanism 8 to exchange heat with the refrigerant flowing through the suction return pipe 12 constituting the superheating mechanism 8. (Refer to point G in FIGS. 26 and 27). Then, the high-pressure refrigerant cooled in the second internal heat exchanger 13 is sent to the outlet pipe 19 b and a part thereof is branched to the suction return pipe 12. The refrigerant flowing through the suction return pipe 12 is depressurized to near low pressure in the suction return valve 12a, and then sent to the second internal heat exchanger 13 (see point H in FIGS. 26 and 27), as described above. In addition, after heat is exchanged with the high-pressure refrigerant cooled in the heat source side heat exchanger 4 as a radiator and heated, the superheat state according to the target value in the superheat degree control of the suction return valve 12a is reached ( 26 and FIG. 27 (see point I), the refrigerant is sent from the use-side heat exchanger 6 serving as an evaporator to the compressor 2. The high-pressure refrigerant cooled in the second internal heat exchanger 13 is sent to the use-side expansion mechanism 5b through the outlet pipe 19b and the outlet check valve 16c of the bridge circuit 16, and is reduced in pressure by the use-side expansion mechanism 5b. Thus, the refrigerant becomes a low-pressure gas-liquid two-phase state and is sent to the use side heat exchanger 6 that functions as a refrigerant evaporator (see point D in FIGS. 26 and 27). Then, the low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 as an evaporator is heated by exchanging heat with water or air as a heating source to evaporate ( (See point E in FIGS. 26 and 27). The low-pressure refrigerant heated and evaporated in the use-side heat exchanger 6 as the evaporator is heated by joining the refrigerant flowing through the suction return pipe 12 that has been overheated in the second internal heat exchanger 13. After being overheated, it is sucked into the compressor 2 (see point A in FIGS. 26 and 27). In this way, the cooling operation is performed.

  During the heating operation, the switching mechanism 3 is in a heating operation state indicated by a solid line in FIG. The opening degree of the expansion mechanism 5 is adjusted. Further, the opening degree of the suction return valve 12a is adjusted in the same manner as in the cooling operation. In the state of the refrigerant circuit 510, low-pressure refrigerant (see point A in FIGS. 26 and 27) is sucked into the compressor 2 and discharged after being compressed to high pressure in the refrigeration cycle (FIGS. 26 and 27). Point B). Then, the high-pressure refrigerant discharged from the compressor 2 is sent via the switching mechanism 3 to the use side heat exchanger 6 that functions as a refrigerant radiator, and water, air, and heat as a cooling source. The cooling is performed after replacement (refer to point C in FIGS. 26 and 27 as point D). Then, the high-pressure refrigerant cooled in the use side heat exchanger 6 as a radiator is decompressed to near the saturation pressure by the use side expansion mechanism 5b (see point J in FIGS. 26 and 27), and then the bridge circuit 16. Flows into the inlet pipe 19a through the inlet check valve 16b and is sent to the second internal heat exchanger 13 constituting the superheat mechanism 8 to exchange heat with the refrigerant flowing through the suction return pipe 12 constituting the superheat mechanism 8. (Refer to point G in FIGS. 26 and 27). Then, the high-pressure refrigerant cooled in the second internal heat exchanger 13 is sent to the outlet pipe 19 b and a part thereof is branched to the suction return pipe 12. The refrigerant flowing through the suction return pipe 12 is depressurized to near low pressure in the suction return valve 12a, and then sent to the second internal heat exchanger 13 (see point H in FIGS. 26 and 27), as described above. In addition, after being heated by exchanging heat with the high-pressure refrigerant cooled in the use side heat exchanger 6 as a radiator, the superheat state corresponding to the target value in the superheat degree control of the suction return valve 12a is reached ( 26 and FIG. 27 (see point I), the refrigerant is sent from the heat source side heat exchanger 4 serving as an evaporator to the compressor 2. The high-pressure refrigerant cooled in the second internal heat exchanger 13 is sent to the heat source side expansion mechanism 5a through the outlet pipe 19b and the outlet check valve 16d of the bridge circuit 16, and is depressurized by the heat source side expansion mechanism 5a. Thus, the refrigerant becomes a low-pressure gas-liquid two-phase state and is sent to the heat source side heat exchanger 4 functioning as an evaporator of the refrigerant (refer to point D in FIGS. 26 and 27 as point C). Then, the low-pressure gas-liquid two-phase refrigerant sent to the heat source side heat exchanger 4 serving as the evaporator is heated by performing heat exchange with water and air serving as the heating source, and evaporates ( (See point E in FIGS. 26 and 27). The low-pressure refrigerant heated and evaporated in the heat source side heat exchanger 4 as the evaporator is heated by joining the refrigerant flowing through the suction return pipe 12 that has been overheated in the second internal heat exchanger 13. After being overheated, it is sucked into the compressor 2 (see point A in FIGS. 26 and 27). In this way, the heating operation is performed.

  As described above, in the air conditioner 1 of the present modification, in the cooling operation, the use side as an evaporator is provided by the superheat mechanism 8 including the suction return pipe 12 and the second internal heat exchanger 13 provided in the refrigerant circuit 510. By heating the refrigerant sent from the heat exchanger 6 to the compressor 2 (see points E and A in FIG. 27), it is possible to prevent the refrigerant sucked into the compressor 2 from becoming wet. Even in the heating operation, the superheater mechanism 8 provided in the refrigerant circuit 510 heats the refrigerant sent from the heat source side heat exchanger 4 as an evaporator to the compressor 2 (see points E and A in FIG. 27). ) Since the refrigerant sucked into the compressor 2 can be prevented from becoming wet, it is possible to reduce the possibility of liquid compression occurring in the compressor 2 in both the cooling operation and the heating operation.

Also in this modified example, as in the above modified example 6, instead of a single refrigerant composed of HFO-1234yf (2,3,3,3-tetrafluoro-1-propene), the molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6) and a single refrigerant comprising a refrigerant having one double bond in the molecular structure Or a mixed refrigerant containing these refrigerants may be used.

  Also in this modification, as shown in FIG. 28, in addition to the above modification 6, in order to reliably prevent the refrigerant sucked into the compressor 2 from becoming wet, as shown in FIG. The refrigerant circuit 510 may be provided with an accumulator 17 that accumulates surplus refrigerant generated due to fluctuations in operating conditions in the refrigerant circuit 510.

  Also in this modified example, as in the above modified example 6, as shown in FIG. 29, in addition to the accumulator 17, heat is radiated in the heat source side heat exchanger 4 or the utilization side heat exchanger 6 as a radiator. The refrigerant circuit 510 may be further provided with a receiver 18 for storing the refrigerant.

Further, in the present modified example, as in the above-described modified example 6, the refrigerant charged in the refrigerant circuit 510 has a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, And m + n = 6), and in the case of a mixed refrigerant including a refrigerant having one double bond in the molecular structure, the accumulator 17 is not provided as shown in FIG. Only the receiver 18 which is located at a high pressure in the cycle and hardly changes the composition of the mixed refrigerant may be provided so as to store the excess refrigerant in the refrigerant circuit 510.

(11) Other Embodiments Embodiments of the present invention and modifications thereof have been described above with reference to the drawings. However, specific configurations are not limited to these embodiments and modifications thereof, and Changes can be made without departing from the scope of the invention.

  For example, in the above-described embodiment and the modification thereof, an example in which the present invention is applied to an air conditioner has been described. However, the present invention is not limited thereto, and the present invention is applied to other refrigeration apparatuses such as a heat pump type hot water heater and a refrigerator. You may apply.

By using the present invention, a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5, and m + n = 6) is used, and a double bond is present in the molecular structure. In a refrigeration apparatus including a single refrigerant composed of one refrigerant or a refrigerant circuit filled with a mixed refrigerant containing this refrigerant, the risk of liquid compression occurring in the compressor can be reduced.

It is a schematic block diagram of the air conditioning apparatus as one Embodiment of the freezing apparatus concerning this invention. It is the pressure-enthalpy diagram in which the refrigerating cycle at the time of air_conditionaing | cooling operation was illustrated. FIG. 2 is a pressure-enthalpy diagram illustrating a refrigeration cycle using HCFC-22. FIG. 4 is a pressure-enthalpy diagram illustrating a refrigeration cycle using HFC-410A. It is a schematic block diagram of the air conditioning apparatus concerning the modification 1. It is a schematic block diagram of the air conditioning apparatus concerning the modification 2. It is a schematic block diagram of the air conditioning apparatus concerning the modification 3. It is a schematic block diagram of the air conditioning apparatus concerning the modification 4. It is the pressure-enthalpy diagram in which the refrigerating cycle at the time of air_conditionaing | cooling operation in the air conditioning apparatus concerning the modification 4 was illustrated. It is a schematic block diagram of the air conditioning apparatus concerning the modification 4. It is a schematic block diagram of the air conditioning apparatus concerning the modification 4. It is a schematic block diagram of the air conditioning apparatus concerning the modification 4. It is a schematic block diagram of the air conditioning apparatus concerning the modification 5. It is a schematic block diagram of the air conditioning apparatus concerning the modification 5. It is a schematic block diagram of the air conditioning apparatus concerning the modification 5. It is a schematic block diagram of the air conditioning apparatus concerning the modification 5. It is a schematic block diagram of the air conditioning apparatus concerning the modification 6. It is a schematic block diagram of the air conditioning apparatus concerning the modification 6. It is a schematic block diagram of the air conditioning apparatus concerning the modification 6. It is a schematic block diagram of the air conditioning apparatus concerning the modification 6. It is a schematic block diagram of the air conditioning apparatus concerning the modification 7. It is the pressure-enthalpy diagram in which the refrigerating cycle at the time of air_conditionaing | cooling operation in the air conditioning apparatus concerning the modification 7 was illustrated. It is a schematic block diagram of the air conditioning apparatus concerning the modification 7. It is a schematic block diagram of the air conditioning apparatus concerning the modification 7. It is a schematic block diagram of the air conditioning apparatus concerning the modification 7. It is a schematic block diagram of the air conditioning apparatus concerning the modification 8. It is the pressure-enthalpy diagram in which the refrigerating cycle at the time of air_conditionaing | cooling operation in the air conditioning apparatus concerning the modification 8 was illustrated. It is a schematic block diagram of the air conditioning apparatus concerning the modification 8. It is a schematic block diagram of the air conditioning apparatus concerning the modification 8. It is a schematic block diagram of the air conditioning apparatus concerning the modification 8.

Explanation of symbols

1 Air conditioning equipment (refrigeration equipment)
2 Compressor 4 Heat source side heat exchanger (radiator, evaporator)
5 Expansion mechanism 5a Heat source side expansion mechanism 5b Usage side expansion mechanism 6 Usage side heat exchanger (evaporator, radiator)
8 Overheating mechanism 10, 110, 210, 310, 410, 510 Refrigerant circuit 11 First internal heat exchanger 12 Suction return pipe 13 Second internal heat exchanger 17 Accumulator 18 Receiver

Claims (9)

A compressor (2) that compresses the refrigerant; a radiator (4, 6) that radiates the refrigerant compressed by the compressor; and an expansion mechanism (5, 5a, 5b) that depressurizes the refrigerant radiated in the radiator. ) And an evaporator (6, 4) for evaporating the refrigerant decompressed in the expansion mechanism, and a molecular formula: C ₃ H _m F _n (where m = 1 to 5, n = 1 to 5 and m + n = 6) and a refrigerant circuit filled with a single refrigerant comprising a refrigerant having one double bond in the molecular structure or a mixed refrigerant containing the refrigerant (10, 110, 210, 310, 410, 510);
An overheating mechanism (8) provided in the refrigerant circuit for heating the refrigerant sent from the evaporator to the compressor;
A refrigeration apparatus (1) comprising:   The superheating mechanism (8) heats the refrigerant sent from the evaporator to the compressor (2) by the refrigerant sent from the radiator (4, 6) to the expansion mechanism (5, 5a, 5b). The refrigeration apparatus (1) according to claim 1, which is an internal heat exchanger (11).   The superheating mechanism (8) branches the refrigerant sent from the radiator (4, 6) to the evaporator (6, 4) and joins the refrigerant sent from the evaporator to the compressor (2). A suction return pipe (12), and a second internal heat exchanger (13) for heating the refrigerant flowing through the suction return pipe by the refrigerant sent from the radiator to the expansion mechanism (5, 5a, 5b). The refrigeration apparatus (1) according to claim 1, wherein:   The accumulator (17) for storing refrigerant sucked into the compressor (2) is provided as a container for storing excess refrigerant in the refrigerant circuit (10, 110, 210, 310, 410, 510). The freezing apparatus (1) in any one of 1-3.   The receiver (18) which accumulate | stores the refrigerant | coolant thermally radiated in the said heat radiator is further provided as a container which accumulate | stores the excess refrigerant | coolant in the said refrigerant circuit (10,110,210,310,410,510). Refrigeration equipment (1). The refrigerant charged in the refrigerant circuit (10, 110, 210, 310, 410, 510) is the mixed refrigerant,
A receiver (18) for storing refrigerant radiated in the radiator (4, 6) without providing an accumulator for collecting refrigerant sucked into the compressor (2) as a container for collecting excess refrigerant in the refrigerant circuit. Is provided,
The refrigeration apparatus (1) according to any one of claims 1 to 3.   The refrigerant filled in the refrigerant circuit (10, 110, 210, 310, 410, 510) is a single refrigerant composed of 2,3,3,3-tetrafluoro-1-propene. The refrigeration apparatus (1) according to any one of the above.   The refrigerant filled in the refrigerant circuit (10, 110, 210, 310, 410, 510) is a mixed refrigerant of 2,3,3,3-tetrafluoro-1-propene and difluoromethane. Refrigeration apparatus (1) in any one of -6.   The refrigerant charged in the refrigerant circuit (10, 110, 210, 310, 410, 510) is a mixed refrigerant of 2,3,3,3-tetrafluoro-1-propene and pentafluoroethane. The refrigeration apparatus (1) according to any one of 1 to 6.

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