JP2015218909A - Refrigeration cycle device and hot water generation device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle device which is more suitable for using a working fluid including R1123.SOLUTION: A refrigeration cycle device includes: a refrigerant circuit 2 in which a compressor 21, a radiator 22, main expansion means 24, and an evaporator 25 are connected in an annular manner by refrigerant piping; and a control device 4 for controlling the main expansion means 24 and the compressor 21. It uses a working fluid which includes equal to or greater than 40 wt.% and less than 75 wt.% of a R1123 refrigerant as a refrigerant circulating in the refrigerant circuit 2. The control device 4 controls the compressor 21 and the main expansion means 24 so that a discharge pressure of the refrigerant discharged from the compressor 21 becomes equal to or less than a predetermined pressure, or a discharge temperature of the refrigerant discharged from the compressor 21 becomes equal to or less than a predetermined temperature. Thus, an operation is performed under a condition where it becomes equal to or less than a lower limit temperature or a lower limit pressure in which disproportionation reaction of the refrigerant occurs, so that disproportionation reaction of the refrigerant does not occur, and low GWP can be achieved while securing reliability.

Description

  The present invention relates to a refrigeration cycle apparatus using a working fluid containing R1123.

  In general, the refrigeration cycle apparatus comprises a compressor, a four-way valve if necessary, a radiator (or a condenser), a decompressor such as a capillary tube or an expansion valve, an evaporator, etc., and constitutes a refrigeration cycle. Cooling or heating action is performed by circulating a refrigerant inside.

  As refrigerants in these refrigeration cycle apparatuses, chlorofluorocarbons (fluorocarbons are described as ROO or ROOXX are defined by the US ASHRAE 34 standard. Hereinafter, they are indicated as ROO or RXX. ) Or halogenated hydrocarbons derived from methane or ethane are known.

  R410A is often used as the refrigerant for the refrigeration cycle apparatus as described above, but the global warming potential (GWP) of the R410A refrigerant is as large as 2090, which is problematic from the viewpoint of preventing global warming.

  Thus, from the viewpoint of preventing global warming, for example, R1123 (1,1,2-trifluoroethylene) and R1132 (1,2-difluoroethylene) have been proposed as refrigerants having a small GWP (for example, patents). Document 1 or Patent document 2).

  Conventionally, as this type of hot water generator, a supercooling heat exchanger is provided downstream of the radiator of the refrigerant circuit, and a part of the mainstream refrigerant is caused to expand and flow into the supercooling heat exchanger, There is one that supercools the mainstream refrigerant that has flowed out of the radiator (see, for example, Patent Document 3).

  This increases the enthalpy difference in the evaporator. Further, by bypassing a part of the mainstream refrigerant, the pressure loss in the evaporator and the suction side piping of the compressor is reduced. Thus, the improvement of the heating / cooling capability as a warm water production | generation apparatus and the improvement of the coefficient of performance of a refrigeration cycle apparatus are aimed at.

International Publication No. 2012/157774 International Publication No. 2012/157765 Japanese Patent No. 3440910

  However, R1123 (1,1,2-trifluoroethylene) and R1132 (1,2-difluoroethylene) are less stable than conventional refrigerants such as R410A and disproportionate when they generate radicals. There is a possibility of changing to another compound by the reaction. Since the disproportionation reaction involves a large heat release, the reliability of the compressor and the refrigeration cycle apparatus may be reduced. For this reason, when using R1123 and R1132 for a compressor and a refrigerating cycle device, it is necessary to suppress this disproportionation reaction.

  In consideration of the above-described conventional problems, the present invention provides a refrigeration cycle apparatus that is more suitable for using a working fluid containing R1123.

  In order to solve the conventional problems, a refrigeration cycle apparatus according to the present invention includes a compressor, a radiator, a main expansion unit, a refrigerant circuit in which an evaporator is annularly connected by a refrigerant pipe, at least the main expansion unit, And a control device for controlling the compressor, wherein a working fluid containing 40 wt% or more and less than 75 wt% of R1123 refrigerant is used as the refrigerant circulating in the refrigerant circuit, and the control device discharges from the compressor Controlling the compressor and the main expansion means so that the discharge pressure of the refrigerant to be discharged is equal to or lower than a predetermined pressure or the discharge temperature of the refrigerant discharged from the compressor is equal to or lower than a predetermined temperature. It is a feature.

  As a result, the compressor and the main expansion means are controlled so that the discharge pressure and the discharge temperature are not more than predetermined values, so that the discharge temperature and discharge pressure of the working fluid rise excessively, and the molecular motion of R1123 in the working fluid. It becomes possible to suppress the disproportionation reaction that occurs as a result of the activation of, and to improve the reliability.

  The present invention can provide a refrigeration cycle apparatus that is more suitable for using a working fluid containing R1123.

1 is a schematic configuration diagram of a refrigeration cycle apparatus and a hot water generation apparatus including the refrigeration cycle apparatus according to Embodiment 1 of the present invention. The graph which shows the area | region where disproportionation reaction arises from the relationship between a composition ratio and a pressure, and the area | region where disproportionation reaction does not occur when the working fluid containing R1123 is used. The graph which shows the area | region where disproportionation reaction arises from the relationship between a pressure and temperature, and the area | region where disproportionation reaction does not take place when the working fluid which contains R1123 75weight% is used The graph which shows the target value of the heat exchange ratio which becomes settled according to a condensation temperature and evaporation temperature in the refrigerating-cycle apparatus in Embodiment 1 of this invention. Flow chart of control during normal operation of the refrigeration cycle apparatus

  A first invention includes a compressor, a radiator, a main expansion unit, a refrigerant circuit in which an evaporator is connected in an annular shape by a refrigerant pipe, at least the main expansion unit, and a control device that controls the compressor, And the control device uses a working fluid containing 40 wt% or more and less than 75 wt% of the R1123 refrigerant as the refrigerant circulating in the refrigerant circuit, and the control device has a discharge pressure of the refrigerant discharged from the compressor equal to or lower than a predetermined pressure. Alternatively, the compressor and the main expansion unit are controlled such that the discharge temperature of the refrigerant discharged from the compressor is equal to or lower than a predetermined temperature.

  As a result, the discharge pressure of the working fluid containing R1123 of 40 wt% or more and less than 75 wt% is equal to or lower than a predetermined pressure (lower limit pressure at which refrigerant disproportionation occurs), or the discharge temperature of the working fluid is predetermined. Since the main expansion means and the compressor are controlled so as to be equal to or lower than the temperature (the lower limit temperature at which the refrigerant disproportionation reaction occurs), the discharge pressure and the discharge temperature are reduced.

  Here, the disproportionation reaction is more likely to occur as the pressure and temperature are higher. Therefore, it becomes possible to suppress the disproportionation reaction that occurs as a result of excessive increase in the discharge pressure and discharge temperature and the activation of the molecular motion of R1123 in the working fluid, thereby improving the reliability.

The second invention is the supercooling heat exchanger provided between the radiator and the main expansion means, and the refrigerant circuit between the radiator and the main expansion means, particularly in the first invention. And a bypass passage connected to the compressor chamber of the compressor or the refrigerant circuit between the evaporator and the compressor via the supercooling heat exchanger, and the supercooling heat exchange Bypass expansion means provided in the bypass path upstream of the evaporator, and the control device is configured so that the dryness of the refrigerant flowing out of the evaporator is 0.8 or more and less than 1.0. The compressor, the main expansion means, and the bypass expansion means are controlled.

  Thereby, the refrigerant dryness at the outlet of the evaporator is between 0.8 and less than 1.0 at which the local evaporation heat transfer coefficient in the horizontal pipe is maximized, so that the heat transfer efficiency of the evaporator is increased. Furthermore, since the refrigerant that does not contribute to evaporation flows to the bypass path side, the refrigerant pressure loss in the evaporator is reduced, and the pressure drop on the compressor suction side is suppressed.

  As a result, in a refrigeration cycle apparatus having a supercooling heat exchanger and a bypass, GWP can be reduced to 1/6 to 1/2 with respect to R410A and R32 by using a mixed refrigerant including R1123, and the refrigerant Therefore, since it is possible to operate at a discharge pressure and a discharge temperature at which no disproportionation reaction occurs, it is possible to simultaneously suppress global warming and ensure the reliability of the device.

  The third invention particularly includes the refrigeration cycle apparatus according to the first or second invention, and heats the liquid as a heat medium in the radiator to use the heat medium for at least one of hot water supply and heating. This is a hot water generator.

  Thereby, there is no need to limit types of radiators such as a water-air heat exchanger and an antifreeze-water heat exchanger.

  Therefore, the heat medium heated by the radiator can be sent to a heating device (a warm air machine, a radiator, a floor heating panel, etc.) or a hot water supply device (a currant, a shower) to perform heating and hot water supply.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of a refrigeration cycle apparatus and a hot water generator in the present embodiment. In FIG. 1, the refrigeration cycle apparatus 1 </ b> A includes a refrigerant circuit 2 that circulates refrigerant, a bypass 3, and a control device 4.

  As the refrigerant circulating in the refrigerant circuit 2, a working fluid containing 40 wt% or more and less than 75 wt% of the R1123 refrigerant having a low GWP is used. This working fluid contains 25 wt% or more and less than 60 wt% of R32 refrigerant in order to suppress the disproportionation reaction of R1123 described later. From the viewpoint of achieving both low GWP and suppression of the disproportionation reaction, R1123 is preferably contained in an amount of 40% by weight or more and less than 60% by weight, and R32 is preferably contained in an amount of 40% by weight or more and less than 60% by weight.

  The refrigerant circuit 2 includes a compressor 21, a radiator 22, a supercooling heat exchanger 23, a main expansion valve (main expansion means) 24, and an evaporator 25 that are annularly connected by piping. In the present embodiment, a sub-accumulator 26 and a main accumulator 27 that perform gas-liquid separation are provided between the evaporator 25 and the compressor 21.

The control device 4 can perform a plurality of operations. The plurality of operations include a normal operation in which the heat medium is heated by the radiator 22 and a defrost operation in which the frost attached to the evaporator 25 is melted. The circulation direction of the refrigerant flowing through the refrigerant circuit 2 is different between the normal operation and the defrost operation.
The refrigerant circuit 2 is provided with a four-way valve 28 for switching the refrigerant circulation direction.

  In the present embodiment, the refrigeration cycle apparatus 1A constitutes the heating means of the hot water generating apparatus that uses the hot water generated by the heating means for heating, and the radiator 22 includes the refrigerant and the heat medium (water or antifreeze liquid). ) And heat exchanger to heat water.

  Specifically, the supply pipe 71 and the recovery pipe 72 are connected to the radiator 22 to configure the heat medium path 70. As for the heat medium, water is supplied to the radiator 22 through the supply pipe 71, and water (hot water) heated by the radiator 22 is collected through the collection pipe 72. The water (hot water) recovered by the recovery pipe 72 is sent, for example, to a heating device such as a radiator or a hot water supply terminal such as a curan directly or indirectly via a hot water storage tank, thereby heating or hot water is performed.

  In the present embodiment, the bypass passage 3 branches from the refrigerant circuit 2 between the supercooling heat exchanger 23 and the main expansion valve 24, and the evaporator 25 and the compressor 21 are connected via the supercooling heat exchanger 23. It is connected to the refrigerant circuit 2 between. In the present embodiment, the bypass path 3 is connected to the refrigerant circuit 2 between the sub accumulator 26 and the main accumulator 27. The bypass passage 3 is provided with a bypass expansion valve (bypass expansion means) 31 on the upstream side of the supercooling heat exchanger 23. The bypass path 3 may be branched from the refrigerant circuit 2 between the supercooling heat exchanger 23 and the main expansion valve 24 and connected to the compression chamber of the compressor 21.

  In the normal operation, the refrigerant discharged from the compressor 21 is sent to the radiator 22 via the four-way valve 28, and in the defrost operation, the refrigerant discharged from the compressor 21 is sent to the evaporator 25 via the four-way valve 28. It is done. In FIG. 1, the direction of refrigerant flow during normal operation is indicated by arrows. Hereinafter, the state change of the refrigerant in the normal operation will be described.

  The high-pressure refrigerant discharged from the compressor 21 flows into the radiator 22 and radiates heat to the water passing through the radiator 22. The high-pressure refrigerant flowing out of the radiator 22 flows into the supercooling heat exchanger 23 and is supercooled by the low-pressure refrigerant decompressed by the bypass expansion valve 31. The high-pressure refrigerant that has flowed out of the supercooling heat exchanger 23 is divided into the main expansion valve 24 side and the bypass expansion valve 31 side.

  The high-pressure refrigerant branched to the main expansion valve 24 side is decompressed and expanded by the main expansion valve 24 and then flows into the evaporator 25. Here, the low-pressure refrigerant flowing into the evaporator 25 absorbs heat from the air. On the other hand, the high-pressure refrigerant branched to the bypass expansion valve 31 side is decompressed and expanded by the bypass expansion valve 31 and then flows into the supercooling heat exchanger 23. The low-pressure refrigerant that has flowed into the supercooling heat exchanger 23 is heated by the high-pressure refrigerant that has flowed out of the radiator 22. Thereafter, the low-pressure refrigerant that has flowed out of the supercooling heat exchanger 23 merges with the low-pressure refrigerant that has flowed out of the evaporator 25, and is sucked into the compressor 21 again.

  The configuration of the refrigeration cycle apparatus 1A in the present embodiment prevents an increase in the compression ratio of the compressor 21 due to a decrease in the outside air temperature and an excessive increase in the discharged refrigerant temperature while suppressing a decrease in operating efficiency. For.

  Next, the working fluid containing R1123 will be described. The working fluid containing R1123 has the advantage of greatly reducing the GWP value, which is a global warming potential, but may cause a disproportionation reaction. The disproportionation reaction is a reaction that changes to a compound when a radical is generated in the refrigeration cycle. Since the disproportionation reaction involves a large heat release, the reliability of the compressor 21 and the refrigeration cycle apparatus 1A may be reduced.

The conditions causing the disproportionation reaction are the close proximity of the intermolecular distance and the state in which the molecular behavior is actively moving from a microscopic viewpoint. In order to use the working fluid containing R1123 in an actual refrigeration cycle apparatus, it is necessary to suppress pressure conditions and temperature conditions to appropriate levels and use them under safe conditions. On the other hand, it is necessary to maximize the functions of the refrigeration cycle apparatus while ensuring safety.

  In the present embodiment, a working fluid containing 40 wt% or more and less than 75 wt% of R1123 refrigerant and 25 wt% or more and less than 60 wt% of R32 refrigerant is used.

  Here, when R32 is mixed with R1123 in an amount of 25% by weight or more, the disproportionation reaction of R1123 can be suppressed. Further, the higher the concentration of R32, the more the disproportionation reaction can be suppressed. This is because the action of mitigating the disproportionation reaction due to the small polarization of R32 to the fluorine atom and the behavior at the time of phase change such as condensation and evaporation are integrated because R1123 and R32 have similar physical characteristics. The disproportionation reaction of R1123 can be suppressed by the action of reducing the disproportionation reaction opportunity due to.

  When the working fluid containing the R1123 refrigerant is used, the disproportionation reaction occurs because the weight ratio of R1123 contained in the working fluid is on the horizontal axis and the pressure is on the vertical axis, depending on the temperature of the working fluid. And as shown in FIG. That is, it means that the disproportionation reaction does not occur in the left region of the line segment drawn according to the temperature of the working fluid, and the disproportionation reaction occurs in the right region of the line segment.

  Here, in a conventional refrigeration cycle apparatus, for example, a conventional refrigeration cycle apparatus using R410A and R32 refrigerants, the discharge pressure (high pressure) of the compressor is about 4 MPa. Here, the operating range of the discharge pressure is almost the same between when the working fluid containing the R1123 refrigerant is used and when the R410A is used. Further, in a conventional hot water generator using ordinary hot water generators, for example, R410A, R407C, and R32 refrigerants, the maximum temperature of the heat medium generated by the radiator 22 is about 70 ° C., so the discharge temperature of the compressor Is about 90 ° C. at the maximum. Based on this, if the range in which the disproportionation reaction of the refrigerant does not occur is defined, the composition ratio of the R1123 refrigerant is 75% by weight at maximum from FIG. Further, since the disproportionation reaction does not occur in the region where the composition ratio of R1123 is less than 40% by weight, the composition ratio of R1123 needs to be 40 to 75% by weight from the viewpoint of achieving a low GWP.

  Further, the mixed refrigerant of R1123 and R32 has an azeotropic boiling point with R32 being 30% by weight and R1123 being 70%, and there is no temperature slip, so that it can be handled in the same manner as a single refrigerant. On the other hand, when R32 is mixed in an amount of 60% by weight or more, temperature slip increases, and handling similar to that of a single refrigerant may be difficult. Therefore, it is desirable to mix R32 in an amount of 60% by weight or less. In particular, it is more desirable to mix R32 in an amount of 40 wt% or more and less than 50 wt% in order to prevent disproportionation and to make the temperature slip smaller because it approaches the azeotropic point and to facilitate device design.

  Tables 1 and 2 show that in the mixed working fluid of R1123 and R32, the pressure, temperature, and compressor displacement of the refrigeration cycle are the same when R32 is 30 wt% to 60 wt%. Refrigeration capacity and cycle efficiency (COP) are calculated and compared with R410A and R1123.

First, calculation conditions in Tables 1 and 2 will be described. In recent years, in order to improve the cycle efficiency of equipment, the performance of heat exchangers has increased, and in actual operating conditions, the condensation temperature tends to decrease, the evaporation temperature tends to increase, and the discharge temperature also tends to decrease . For this reason, considering the actual operating conditions, the cooling calculation conditions in Table 1 are the cooling operation of the air conditioner (indoor dry bulb temperature: 27 ° C., wet bulb temperature: 19 ° C., outdoor dry bulb temperature: 35 ° C.) The evaporation temperature is 15 ° C, the condensation temperature is 45 ° C,
The superheat degree of the refrigerant sucked in the compressor is 5 ° C., and the supercool degree of the condenser outlet is 8 ° C.

  The heating calculation conditions in Table 2 are the calculation conditions corresponding to the heating operation of the air conditioner (indoor dry bulb temperature: 20 ° C., outdoor dry bulb temperature: 7 ° C., wet bulb temperature: 6 ° C.), and the evaporation temperature. Is 2 ° C., the condensation temperature is 38 ° C., the superheat degree of the refrigerant sucked into the compressor is 2 ° C., and the supercool degree at the condenser outlet is 12 ° C.

From Tables 1 and 2, by mixing R32 at 30 wt% or more and 60 wt% or less, refrigeration capacity and cycle efficiency (COP) are equivalent to R410A during cooling and heating operation, and the warming coefficient is R410A. It can be reduced to 10 to 20%.

  As described above, in the two-component system of R1123 and R32, taking into consideration the prevention of disproportionation, the magnitude of temperature slip, the capacity during cooling operation / heating operation, and COP (that is, compression described later) When a mixing ratio suitable for an air-conditioning apparatus using an air conditioner is specified, a mixture containing 30% by weight or more and 60% by weight or less R32 is desirable, and a mixture containing 40% by weight or more and 50% by weight or less R32 is more desirable. Is desirable.

  In order to avoid the occurrence of the disproportionation reaction of the refrigerant in the presence of such constraint conditions, the discharge pressure of the compressor 21 during normal operation, in particular, using a working fluid containing R1123 at a predetermined composition ratio. Among the combined conditions of the discharge temperature and the discharge temperature, it is necessary to set the operation conditions in which the disproportionation reaction does not occur.

In order to increase the efficiency of the refrigeration cycle apparatus 1A, it is necessary to increase the enthalpy difference in the evaporator 25 by supercooling and to bypass the wet refrigerant from the bypass passage 3. Thereby, the refrigerant circuit 2 while reducing the suction refrigerant enthalpy of the compressor 21.
The pressure loss on the low pressure side can be reduced.

  Therefore, in the present invention, in order to achieve both the reliability and high efficiency of the device, the degree of refrigerant subcooling on the outlet side of the supercooling heat exchanger 23 and the amount of refrigerant flowing through the bypass passage 3 are adjusted appropriately. This suppresses a decrease in operating efficiency of the refrigeration cycle apparatus 1A.

  In the present invention, as shown in FIG. 3, at a predetermined R1123 composition ratio (in the case of 75% in FIG. 3), the relationship between the refrigerant pressure Px at which disproportionation reaction does not occur and the refrigerant temperature Tx is preliminarily expressed as a correlation approximation expression. I ask for it. The control device 4 determines the rotational speed of the compressor 21 and the main expansion so that the refrigerant discharge temperature Td is equal to or lower than a predetermined refrigerant temperature Tx that does not cause a disproportionation reaction in accordance with the detected refrigerant discharge pressure. The valve opening degree of the valve 24 is controlled, and when the bypass expansion valve 31 is provided, the bypass expansion valve 31 is also controlled. Further, the control device 4 determines the rotational speed of the compressor 21 so that the refrigerant discharge pressure Pd is equal to or lower than a predetermined refrigerant pressure Px at which disproportionation reaction does not occur, according to the detected refrigerant discharge temperature. The valve opening degree of the main expansion valve 24 is controlled, and when the bypass expansion valve 31 is provided, the bypass expansion valve 31 is also controlled.

  Next, a control operation performed by the control device 4 will be described.

  As shown in FIG. 1, the refrigerant circuit 2 includes a first temperature sensor 61 that detects the temperature (evaporation temperature) Te of the refrigerant flowing into the evaporator 25, and the temperature of the refrigerant that flows out of the evaporator 25 (evaporator outlet). A second temperature sensor 62 for detecting the temperature) Teo; a third temperature sensor 63 for detecting the discharge temperature of the refrigerant discharged from the compressor 21; and a pressure (condensation pressure) Pc of the refrigerant flowing into the radiator 22; A pressure sensor 51 is provided.

  Based on the detection values detected by the various sensors 51, 61, 62, 63, the control device 4 switches the rotation speed of the compressor 21, the four-way valve 28, and the main expansion valve 24 and the bypass expansion valve 31. Control the opening.

  In the present embodiment, the control device 4 controls the main expansion valve 24 and the bypass expansion valve so that the dryness of the refrigerant flowing out from the evaporator 25 in the refrigerant circuit 2 is 0.8 or more and less than 1.0 in the normal operation. 31.

  Specifically, the temperature difference ΔTe between the evaporation temperature Te detected by the first temperature sensor 61 and the evaporator outlet temperature Teo detected by the second temperature sensor 62 is set to a predetermined temperature difference ΔTt. The opening degree of the main expansion valve 24 is adjusted. If the temperature difference ΔTe is large, the opening of the main expansion valve 24 is opened, and if the temperature difference ΔTe is small, the opening of the main expansion valve 24 is closed.

  In order to set the dryness of the refrigerant flowing out of the evaporator 25 to a predetermined value, the second temperature sensor 62 is attached to the downstream side of the four-way valve 28 so that the refrigerant flowing out of the evaporator 25 is inside the four-way valve 28. The temperature after absorbing heat from the refrigerant discharged from the compressor 21 is detected, and the temperature difference at which the dryness becomes a desired value may be set to ΔTt.

  Further, the control device 4 detects the opening degree of the bypass expansion valve 31 by the saturation temperature (condensation temperature) Tc calculated based on the condensation pressure Pc detected by the pressure sensor 51 and the first temperature sensor 61. A predetermined opening degree Sb determined by the evaporation temperature Te is set. The predetermined opening degree Sb is set such that the heat exchange ratio Qsc / Qc increases as the evaporation temperature Te decreases and as the condensation temperature Tc increases.

Generally, when the degree of supercooling in the supercooling heat exchanger 23 is the same due to a decrease in the evaporation temperature Te in the evaporator 25 due to a decrease in the outside air temperature or the like, and an increase in the condensation temperature Tc in the radiator 22 due to an increase in the water temperature. Since the dryness of the refrigerant flowing into the evaporator 25 increases and the refrigerant gas components that do not contribute to evaporation increase, the heat absorption capability of the evaporator 25 decreases.

  In such a case, as shown in FIG. 4, the control device 4 causes the main expansion valve 24 and the bypass expansion valve so that the heat exchange ratio Qsc / Qc increases as the evaporation temperature Te decreases and the condensation temperature Tc increases. 31 is preferably controlled.

  In this way, the degree of supercooling at the outlet of the supercooling heat exchanger 23 can be increased, and by reducing the enthalpy of the refrigerant flowing into the evaporator 25, evaporation can be performed compared to the case where the heat exchange ratio Qsc / Qc is small. The amount of change in the enthalpy of the refrigerant in the vessel 25 can be increased, that is, the heat absorption capacity can be increased.

  As a result, when the outside air temperature is lowered or the water temperature is raised, the decrease in the amount of heat absorbed by the evaporator 25 due to the increase in the enthalpy of the refrigerant flowing into the evaporator 25 can be compensated.

  Further, the control device 4 obtains the lower limit pressure at which the disproportionation reaction of the refrigerant occurs or the disproportionation of the refrigerant from the correlation approximation equation of the refrigerant pressure Px and the refrigerant temperature Tx at which the refrigerant disproportionation reaction is obtained in advance. The lower limit temperature at which the chemical reaction occurs is determined.

  The control device 4 rotates the compressor 21 so that the discharge temperature detected by the third temperature sensor 63 is equal to or lower than the lower limit temperature, or the discharge pressure detected by the pressure sensor 51 is equal to or lower than the lower limit pressure. The number, the opening of the main expansion valve 24, and the opening of the bypass expansion valve 31 are controlled. Thereby, generation | occurrence | production of disproportionation reaction can be prevented.

  Next, control of the control device 4 during normal operation will be described with reference to a flowchart shown in FIG. First, the control device 4 detects the evaporation temperature Te with the first temperature sensor 61 and the evaporator outlet temperature Teo with the second temperature sensor 62 (step S1). Thereafter, the control device 4 calculates the temperature difference ΔTe by Teo = Te (step S2). Then, the control device 4 adjusts the opening of the main expansion valve 24 so that the temperature difference ΔTe becomes a target temperature difference ΔTt that is set in advance so that the refrigerant dryness at the outlet of the evaporator 25 becomes appropriate (step). S3).

  Next, the control device 4 detects the condensation pressure Pc with the pressure sensor 51 (step S4), and calculates a saturation temperature (condensation temperature) Tc at the pressure of the refrigerant flowing into the radiator 22 from the detected condensation pressure Pc. (Step S5). The calculation of the condensation temperature Tc is performed using a refrigerant physical property formula. Thereafter, the control device 4 determines a set opening degree Sb corresponding to the current evaporation temperature Te and the condensation temperature Tc from a set opening degree table determined by the predetermined values of the evaporation temperature Te and the condensation temperature Tc ( Step S6), the opening degree of the bypass expansion valve 31 is adjusted to the set opening degree Sb (Step S7). At this time, the control device 4 causes the compressor so that the discharge temperature detected by the third temperature sensor 63 is lower than the lower limit temperature or the discharge pressure detected by the pressure sensor 51 is lower than the lower limit pressure. 21, the opening degree of the main expansion valve 24, and the opening degree of the bypass expansion valve 31 are controlled.

  As described above, in the present embodiment, the compressor 21, the radiator 22, the supercooling heat exchanger 23, the main expansion means 24, and the evaporator 25 are connected in a ring shape, and the radiator 22 A bypass path 3 branched from the refrigerant circuit 2 between the main expansion means 24 and connected to the refrigerant circuit between the evaporator 25 and the compressor 21 via the bypass expansion means 31 and the supercooling heat exchanger 23; The control device 4 includes a pressure sensor 51 that detects the discharge pressure of the refrigerant discharged from the compressor 21 and / or a third temperature sensor 63 that detects the discharge temperature of the refrigerant discharged from the compressor 21. As a working fluid, a working fluid containing 40 wt% or more and less than 75 wt% of R1123 refrigerant is circulated.

  In such a refrigeration cycle apparatus 1A, the opening degree of the main expansion means 24 and the bypass expansion means 31 is adjusted so that the dryness of the refrigerant flowing out of the evaporator 25 is 0.8 or more and less than 1.0. . Further, the discharge pressure Pd of the refrigerant discharged from the compressor 21 is equal to or lower than a predetermined pressure (lower limit pressure at which the disproportionation reaction of the refrigerant occurs) Px, or the discharge temperature of the refrigerant discharged from the compressor 21 The refrigerant flow rate is controlled such that Td is equal to or lower than a predetermined temperature (a lower limit temperature at which a refrigerant disproportionation reaction occurs) Tx.

  As a result, the discharge pressure Pd and the discharge temperature Td of the working fluid containing R1123 of 40 wt% or more and less than 75 wt% are suppressed from excessively rising. Therefore, since the temperature condition in which the disproportionation reaction of the refrigerant occurs is relatively high, the temperature is out of the region in which the disproportionation reaction occurs. As a result, the use of a refrigerant including R1123 can reduce the GWP to 1/6 to 1/2 with respect to R410A and R32, and operation at a discharge pressure and temperature that does not cause the refrigerant disproportionation phenomenon. Therefore, it is possible to both suppress global warming and ensure the reliability of the equipment.

  In the present embodiment, the control device 4 controls the main expansion valve 24 so that the dryness of the refrigerant flowing out of the evaporator 25 during normal operation is 0.8 or more and less than 1.0. Even if the loads on the evaporation side and the condensation side change, the refrigerant dryness at the outlet of the evaporator 25 becomes appropriate according to the load, so that the reliability and energy saving of the refrigeration cycle are improved.

  Further, in the present embodiment, the bypass expansion valve 31 is controlled such that the heat exchange ratio increases as the evaporation temperature Te in the evaporator 25 decreases and the condensation temperature Tc in the radiator 22 increases.

  As a result, an increase in the refrigerant enthalpy at the inlet of the evaporator 25 due to a decrease in the evaporation temperature Te or an increase in the condensation temperature Tc is suppressed, and the gas-phase refrigerant at the inlet of the evaporator 25 is reliably bypassed by the bypass path. The pressure loss on the low pressure side is reduced.

  Therefore, even when the outside air temperature decreases or the circulating water temperature rises, highly efficient operation can be maintained.

  In FIG. 1, the pressure sensor 51 is provided between the four-way valve 28 and the radiator 22 in the refrigerant circuit 2, but the pressure sensor 51 extends from the discharge portion of the compressor 21 to the inlet portion of the main expansion valve 24. As long as it is between, it may be provided at any position in the refrigerant circuit 2, and the pressure loss from the radiator 22 to the pressure sensor 51 may be corrected.

  Further, instead of the pressure sensor 51, a temperature sensor may be installed at a portion where the condensed refrigerant in the radiator 22 is in a two-phase state, and the temperature detected by the temperature sensor may be set as the condensation temperature Tc.

  Further, instead of the first temperature sensor 61, a pressure sensor is installed between the outlet of the main expansion valve 24 and the suction part of the compressor 21, and the saturation temperature is calculated based on the pressure detected by this pressure sensor. The evaporation temperature Te may be used.

  Further, the bypass passage 3 is not necessarily branched from the refrigerant circuit 2 between the supercooling heat exchanger 23 and the main expansion valve 24, and the refrigerant circuit 2 is interposed between the radiator 22 and the supercooling heat exchanger 23. You may branch from.

Furthermore, the main expansion means and bypass expansion means of the present invention are not necessarily expansion valves, and may be an expander that recovers power from the expanding refrigerant. In this case, for example, the rotational speed of the expander may be controlled by changing the load with a generator connected to the expander.

  Further, the fluid to be heated that is heated by the radiator 22 is not necessarily water, and may be air. That is, the present invention can also be applied to an air conditioner.

  INDUSTRIAL APPLICABILITY The present invention is particularly useful for a hot water generating device that heats water with a refrigeration cycle device and uses the water for hot water supply or heating.

DESCRIPTION OF SYMBOLS 1A Refrigeration cycle apparatus 2 Refrigerant circuit 3 Bypass path 4 Control apparatus 21 Compressor 22 Radiator 23 Supercooling heat exchanger 24 Main expansion valve (main expansion means)
25 Evaporator 31 Bypass expansion valve (Bypass expansion means)
51 Pressure Sensor 61 First Temperature Sensor 62 Second Temperature Sensor 63 Third Temperature Sensor

Claims (3)

A compressor, a radiator, main expansion means, a refrigerant circuit in which an evaporator is annularly connected by a refrigerant pipe, and at least the main expansion means, and a control device for controlling the compressor,
Using a working fluid containing 40 wt% or more and less than 75 wt% of R1123 refrigerant as the refrigerant circulating in the refrigerant circuit,
The control device is configured so that the discharge pressure of the refrigerant discharged from the compressor is equal to or lower than a predetermined pressure, or the discharge temperature of the refrigerant discharged from the compressor is equal to or lower than a predetermined temperature. And a refrigeration cycle apparatus for controlling the main expansion means. A supercooling heat exchanger provided between the radiator and the main expansion means;
Branching from the refrigerant circuit between the radiator and the main expansion means, via the supercooling heat exchanger, between the compressor chamber of the compressor or between the evaporator and the compressor A bypass connected to the refrigerant circuit;
A bypass expansion means provided in the bypass path upstream of the supercooling heat exchanger,
The control device controls the compressor, the main expansion unit, and the bypass expansion unit so that the dryness of the refrigerant flowing out of the evaporator is 0.8 or more and less than 1.0. The refrigeration cycle apparatus according to claim 1. Comprising the refrigeration cycle apparatus according to claim 1 or 2,
Heat the liquid as a heat medium in the radiator,
A hot water generation apparatus using the heat medium for at least one of hot water supply and heating.