Refrigeration device

Abstract

A refrigeration device (90) comprises housings (105; 205), a refrigerant circuit (60), power supply units (45; 46), grounding lines (51; 95), and grounding resistors (55; 94). The refrigerant circuit (60) circulates a refrigerant (65) that can cause a disproportionation reaction. The power supply units (45; 46) receive power from a commercial power supply (47). The grounding lines (51; 95) electrically connect the housings (105; 205) to an external grounding surface (G). The grounding resistors (55; 94) are electrically connected to the grounding lines (51; 95) and have a resistance value of 0.1Ω or greater.

Description

Refrigeration equipment

[0001] The present disclosure relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus having a refrigerant circuit that circulates a refrigerant that may undergo a disproportionation reaction.

[0002] The refrigeration device disclosed in Patent Document 1 (International Publication No. WO2018 / 168776) uses a refrigerant that is prone to undergo a self-decomposition reaction known as a disproportionation reaction.

[0003] There is room for suppressing disproportionation reactions in refrigeration equipment by reducing discharge inside the compressor, etc.

[0004] A refrigeration apparatus according to a first aspect includes a housing, a refrigerant circuit, a power supply unit, a grounding wire, and a grounding resistor. The refrigerant circuit circulates a refrigerant capable of causing a disproportionation reaction. The power supply unit receives power from a commercial power source. The grounding wire connects the housing to a ground outside the housing. The grounding resistor is connected to the grounding wire and has a resistance of 0.1 Ω or more.

[0005] According to this configuration, when discharge energy that may cause a disproportionation reaction of the refrigerant is generated inside the refrigeration device, the discharge energy can be consumed by the grounding resistor, thereby suppressing the disproportionation reaction of the refrigerant.

[0006] A refrigeration apparatus according to a second aspect is the refrigeration apparatus according to the first aspect, further comprising a compressor, the compressor having a compressor housing, and the ground wire being electrically connected to the compressor housing.

[0007] With this configuration, discharge energy that could induce a disproportionation reaction of the refrigerant inside the refrigeration system is propagated through the grounding wire that is electrically connected to the compressor housing and is dissipated by the grounding resistor, thereby suppressing the disproportionation reaction of the refrigerant.

[0008] A refrigeration apparatus according to a third aspect is the refrigeration apparatus according to the first or second aspect, further comprising a utilization heat exchanger, wherein the grounding wire is electrically connected to the utilization heat exchanger.

[0009] With this configuration, the discharge energy that could induce a disproportionation reaction of the refrigerant inside the refrigeration system is propagated through the grounding wire that is electrically connected to the utilization heat exchanger and is consumed by the grounding resistor, thereby suppressing the disproportionation reaction of the refrigerant.

[0010] A refrigeration apparatus according to a fourth aspect is the refrigeration apparatus according to the first aspect, further comprising a compressor and a utilization heat exchanger. The compressor comprises a compressor housing. The grounding resistor comprises a first grounding resistor and a second grounding resistor. The grounding wire comprises a first grounding wire and a second grounding wire. The first grounding wire is electrically connected to the first grounding resistor and the compressor housing. The second grounding wire is electrically connected to the second grounding resistor and the utilization heat exchanger.

[0011] With this configuration, if a break occurs in one of the first and second grounding wires, the discharge energy propagates to the other and is consumed by the grounding resistor, thereby more reliably suppressing the disproportionation reaction of the refrigerant.

[0012] A refrigeration apparatus according to a fifth aspect is the refrigeration apparatus according to any one of the first aspect to the fourth aspect, wherein the refrigerant contains 1,2-difluoroethylene (HFO-1132).

[0013] According to this configuration, the refrigerant contains HFO-1132, which is prone to disproportionation reactions, and therefore the disproportionation reactions of HFO-1132 can be suppressed.

[0014] A refrigeration apparatus according to a sixth aspect is the refrigeration apparatus according to the fifth aspect, wherein the refrigerant further contains 2,3,3,3-tetrafluoropropene (HFO-1234yf).

[0015] According to this configuration, since the refrigerant contains HFO-1134yf, the flammability of the refrigerant can be reduced.

[0016] A refrigeration apparatus according to a seventh aspect is the refrigeration apparatus according to the sixth aspect, wherein the resistance value of the grounding resistor is R (Ω). The ratio of 1,2-difluoroethylene (HFO-1132) in the refrigerant is A (mass %). The discharge energy applied to the refrigerant is E (J). The pressure when the refrigerant is used is P (MPa). Any one of a first condition, a second condition, and a third condition is satisfied. The first condition is R≧0.1 (Ω), E≦1000 (J), A≦32 (mass %), and P≦6 (MPa). The second condition is R≧1.0 (Ω), E≦250 (J), A≦45 (mass %), and P≦2 (MPa). The third condition is R≧10.0 (Ω), E≦30 (J), A≦55 (mass %), and P≦1 (MPa).

[0017] This configuration allows the grounding resistor to sufficiently consume the discharge energy generated inside the refrigeration system, thereby suppressing disproportionation reactions in the refrigerant composition defined by "A" of the first to third conditions.

[0018] A refrigeration apparatus according to an eighth aspect is the refrigeration apparatus according to any one of the first aspect to the seventh aspect, wherein the grounding resistor is physically connected to the grounding line.

[0019] According to this configuration, the grounding resistor is physically connected to the grounding wire, and no modification to the inside of the unit is required, so the space inside the housing is not compressed.

[0020] 1 is a schematic diagram showing a refrigerant circuit 60 and an electrical system 40 of a refrigeration device 90. FIG. 1 is a schematic diagram showing the electrical system 40. FIG. 2 is a cross-sectional view of a compressor 11. FIG. 3 is a schematic diagram of the structure of a heat source unit 10. FIG. 4 is a diagram showing discharge locations of the compressor 11. FIG. 5 is a model showing discharge within a compressor. FIG. 6 is a graph showing the relationship between discharge time, discharge energy, and resistance value. FIG. 7 is a graph showing the relationship between refrigerant composition, refrigerant pressure, and discharge energy. FIG. 8 is a graph showing a first condition with dots. FIG. 9 is a graph showing a first condition with dots. FIG. 10 is a graph showing a second condition with dots. FIG. 11 is a graph showing a third condition with dots. FIG. 12 is a graph showing a third condition with dots.

[0021] <Embodiment> (1) Overall Configuration Fig. 1 is a schematic diagram showing a refrigerant circuit 60 and an electrical system 40 of a refrigeration device 90 according to the present disclosure. The refrigeration device 90 may be configured as a product such as an air conditioner, a refrigerator, a water heater, or a floor heating device. The refrigeration device 90 has a heat source unit 10, a utilization unit 20, a connecting pipe group 30, and a cable 43. The refrigeration device 90 is installed in an on-site IP. A commercial power source 47 supplies power to the refrigeration device 90. An outlet of the commercial power source 47 transmits power from a commercial power transformer X installed in an off-site OP to the refrigeration device 90.

[0022] (2) Detailed Configuration (2-1) Heat Source Unit 10 The heat source unit 10 is for generating cold or heat from a heat source such as outside air. The heat source unit 10 has a heat source housing 105, a compressor 11, a four-way switching valve 12, a heat source heat exchanger 13, a heat source fan 14, a heat source expansion valve 15, an accumulator 16, a liquid shut-off valve 17, a gas shut-off valve 18, and internal piping T1 to T7. The heat source unit 10 further has a heat source control unit 19 and a heat source power supply unit 45 that constitute an electrical system 40.

[0023] (2-1-1) Compressor 11 The compressor 11 is a device that compresses the refrigerant 65 in a low-pressure gas state to a high-pressure gas state. The compressor 11 is disposed inside the heat source housing 105. The compressor 11 is provided with a suction pipe 112 for drawing in the refrigerant 65 and a discharge pipe 111 for discharging the refrigerant 65. The structure of the compressor 11 will be described later.

[0024] (2-1-2) Four-way switching valve 12 The four-way switching valve 12 is a device that switches between a cold energy utilization operation that provides cold energy to the user and a hot energy utilization operation that provides hot energy to the user by switching the path of the refrigerant 65. Details will be described later in the description of the refrigerant circuit 60.

[0025] (2-1-3) Heat Source Heat Exchanger 13 The heat source heat exchanger 13 is a device that exchanges heat between the refrigerant 65 and air. The heat source heat exchanger 13 functions as a condenser during cold heat utilization operation and as an evaporator during hot heat utilization operation. The heat source heat exchanger 13 may be a device that exchanges heat between a medium such as water and the refrigerant.

[0026] (2-1-4) Heat Source Fan 14 The heat source fan 14 generates an airflow to promote heat exchange in the heat source heat exchanger 13. The airflow generated by the heat source fan 14 moves air outside the heat source housing 105, which functions as a heat source, into the heat source housing 105, and moves air that has completed heat exchange with the refrigerant 65 in the heat source heat exchanger 13 to the outside of the heat source housing 105. The heat source fan 14 is driven by a heat source fan motor.

[0027] (2-1-5) Heat Source Expansion Valve 15 The heat source expansion valve 15 is a mechanism for reducing the pressure of the refrigerant 65 in a high-pressure liquid state to a low-pressure gas-liquid two-phase state. Furthermore, the heat source expansion valve 15 can adjust the circulation amount of the refrigerant 65.

[0028] (2-1-6) Accumulator 16 The accumulator 16 is a container that removes and stores components of the liquid refrigerant 65 that are mixed in the gas refrigerant 65.

[0029] (2-1-7) Liquid Shut-Off Valve 17 and Gas Shut-Off Valve 18 The liquid shut-off valve 17 and gas shut-off valve 18 are valves that are manually opened and closed by the installer of the refrigeration device 90, and are used to cut off the refrigerant path.

[0030] (2-1-8) Internal Pipes T1 to T7 The internal pipes T1 to T7 are pipes that connect components arranged inside the heat source housing 105. Specifically, the internal pipe T1 connects the discharge pipe 111 and the four-way switching valve 12. The internal pipe T2 connects the four-way switching valve 12 and the heat source heat exchanger 13. The internal pipe T3 connects the heat source heat exchanger 13 and the heat source expansion valve 15. The internal pipe T4 connects the heat source expansion valve 15 and the liquid stop valve 17. The internal pipe T5 connects the gas stop valve 18 and the four-way switching valve 12. The internal pipe T6 connects the four-way switching valve 12 and the accumulator 16. The internal pipe T7 connects the accumulator 16 and the suction pipe 112.

[0031] (2-1-9) Heat Source Control Unit 19 and Heat Source Power Supply Unit 45 The heat source control unit 19 reads the outputs of various sensors housed in the heat source unit 10 and controls various actuators. The heat source power supply unit 45 adjusts the various power supply voltages required by the heat source unit 10. Additional explanation of these units will be provided in the explanation of the electrical system 40.

[0032] (2-2) Usage Unit 20 The usage unit 20 is for providing cold or hot heat to a user. The usage unit 20 has a usage housing 205, a usage heat exchanger 23, and a usage fan 24. The usage unit 20 further has a usage control unit 29 and a usage power supply unit 46 that constitute the electrical system 40.

[0033] (2-2-1) Usage Heat Exchanger 23 The usage heat exchanger 23 is a device that exchanges heat between the refrigerant 65 and air. The usage heat exchanger 23 functions as an evaporator during cold heat usage operation, and as a condenser during hot heat usage operation. The usage heat exchanger 23 may be a device that exchanges heat between a medium such as water and a refrigerant. The usage heat exchanger 23 is disposed inside the usage housing 205.

[0034] (2-2-2) Usage Fan 24 The usage fan 24 promotes heat exchange in the usage heat exchanger 23 by generating airflow. In addition, if the refrigeration device 90 is an air conditioner, the usage fan 24 sends conditioned air to the user's location. If the refrigeration device 90 is a water heater, the usage fan 24 may be in the form of a pump that carries hot water to the user's location. The usage fan 24 is driven by a usage fan motor.

[0035] (2-2-3) Usage Control Unit 29 and Usage Power Supply Unit 46 The usage control unit 29 reads the outputs of various sensors stored in the usage unit 20 and controls various actuators. The usage power supply unit 46 adjusts the various power supply voltages required by the usage unit 20. Additional explanation of these units will be provided in the explanation of the electrical system 40.

[0036] (2-3) Communication Pipe Group 30 The communication pipe group 30 is a pipe that connects the heat source unit 10 and the utilization unit 20. The communication pipe group 30 has a liquid communication pipe 31 and a gas communication pipe 32. The liquid communication pipe 31 connects the liquid shut-off valve 17 and the utilization heat exchanger 23. The gas communication pipe 32 connects the gas shut-off valve 18 and the utilization heat exchanger 23.

[0037] (2-4) Cable 43 The cable 43 constitutes a part of the electrical system 40. The cable 43 will be explained in more detail in the explanation of the electrical system 40.

[0038] (3) Refrigerant Circuit 60 (3-1) Refrigerant 65 The refrigerant circuit 60 circulates the refrigerant 65 .

[0039] In the refrigerant circuit 60, the refrigerant 65 is compressed, releases heat or condenses, is decompressed, absorbs heat or evaporates, and then is compressed again. The refrigerant circuit 60 is composed of a heat-source refrigerant circuit 61, a utilization refrigerant circuit 62, and a communication pipe group 30. The heat-source refrigerant circuit 61 is composed of a part of the heat source unit 10. The heat-source refrigerant circuit 61 includes, as main elements, a compressor 11, a four-way switching valve 12, a heat-source heat exchanger 13, a heat-source expansion valve 15, and internal pipes T1 to T7. The utilization refrigerant circuit 62 is composed of a part of the utilization unit 20. The utilization refrigerant circuit 62 includes a utilization heat exchanger 23.

[0040] The refrigerant 65 is of a type that can undergo disproportionation reactions.

[0041] The refrigerant 65 is a mixed refrigerant containing the following components 1 and 2:

[0042] Component 1: 1,2-difluoroethylene (HFO-1132) Component 2: 2,3,3,3-tetrafluoropropene (HFO-1234yf) Of the two, component 1 is more strongly involved in the occurrence of the disproportionation reaction. The molecular formula of component 1 is as follows:

[0043] Component 1 may be, for example, cis-1,2-difluoroethylene (HFO-1132(Z)). Alternatively, component 1 may be trans-1,2-difluoroethylene (HFO-1132(E)). Furthermore, component 1 may be trifluoroethylene (HFO-1123).

[0044] (3-2) Cold Energy Utilization Operation Referring to FIG. 1 , operation when a user utilizes cold energy will be described. In this case, the four-way switching valve 12 realizes the connections shown by the solid lines. The low-pressure gas refrigerant 65 is compressed by the compressor 11. The high-pressure gas refrigerant 65 is discharged from the discharge pipe 111. The high-pressure gas refrigerant 65 is condensed in the heat source heat exchanger 13 and releases heat into the air as it becomes a high-pressure liquid. The high-pressure liquid refrigerant 65 is then decompressed by the heat source expansion valve 15 and becomes a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant 65 is evaporated in the utilization heat exchanger 23 and absorbs heat from the air as it becomes a low-pressure gas. This means that the refrigerant 65 provides cold energy to the user's environment. When the low-pressure gas refrigerant 65 passes through the accumulator 16, trace amounts of liquid refrigerant mixed in the low-pressure gas refrigerant 65 are separated. Next, the refrigerant 65 in a low-pressure gas state is sucked into the compressor 11 through the suction pipe 112 .

[0045] (3-3) Heat Utilization Operation Referring to FIG. 1 , operation when a user utilizes heat will be described. In this case, the four-way switching valve 12 realizes the connections shown by the dashed lines. The low-pressure gas refrigerant 65 is compressed by the compressor 11. The high-pressure gas refrigerant 65 is discharged from the discharge pipe 111. The high-pressure gas refrigerant 65 is condensed in the utilization heat exchanger 23 and releases heat into the air as it becomes a high-pressure liquid. This means that the refrigerant 65 provides heat to the user's environment. Next, the high-pressure liquid refrigerant 65 is decompressed by the heat source expansion valve 15 and becomes a low-pressure gas-liquid two-phase refrigerant. The low-pressure gas-liquid two-phase refrigerant 65 is evaporated in the heat source heat exchanger 13 and absorbs heat from the air as it becomes a low-pressure gas. When the low-pressure gas refrigerant 65 passes through the accumulator 16, traces of liquid refrigerant mixed in the low-pressure gas refrigerant 65 are separated. Next, the refrigerant 65 in a low-pressure gas state is sucked into the compressor 11 through the suction pipe 112 .

[0046] (4) Electrical System 40 Fig. 2 is a schematic diagram showing the electrical system 40 of the refrigeration device 90. The electrical system 40 has a utilization power supply unit 46, a utilization control unit 29, a heat source power supply unit 45, and a heat source control unit 19.

[0047] (4-1) Usage Power Supply Unit 46 The usage power supply unit 46 has a rectifier 461 and a regulator 462. The rectifier 461 rectifies the AC power received from the commercial power supply 47 to generate a DC power supply voltage V1 with respect to the ground potential GND. The power supply voltage V1 has a magnitude sufficient to drive various actuators including motors. The regulator 462 generates a power supply voltage V2 that is smaller than the power supply voltage V1. The power supply voltage V2 is used to drive a signal processing circuit including a processor.

[0048] (4-2) Usage Control Unit 29 The usage control unit 29 receives the power supply voltage V1, the power supply voltage V2, and the ground potential GND from the usage power supply unit 46, and generates control signals for driving various actuators including the usage fan 24.

[0049] (4-3) Cable 43 The cable 43 connects the utilization unit 20 and the heat source unit 10, and constitutes part of the electrical system 40. The cable 43 houses a power line 41, a ground line 42, and a communication line 49. The power line 41 transmits the power supply voltage. The power line 41 includes a first power line 41a and a second power line 41b. The first power line 41a transmits the power supply voltage V1. The second power line 41b transmits the power supply voltage V2. The ground line 42 transmits the ground potential GND, which is the reference potential for the power supply voltage. The communication line 49 transmits communication signals between the heat source control unit 19 and the utilization control unit 29.

[0050] (4-4) Heat Source Power Supply Unit 45 The heat source power supply unit 45 has capacitors 451 and 452 that smooth the power supply voltages V1 and V2 transmitted via the cable 43, respectively.

[0051] (4-5) Heat Source Control Unit 19 The heat source control unit 19 receives the supply voltage V1, the supply voltage V2, and the ground potential GND from the heat source power supply unit 45, and generates control signals to drive various actuators including the compressor 11, the four-way switching valve 12, the heat source fan 14, and the heat source expansion valve 15. The heat source control unit 19 is connected to the utilization control unit 29 by a communication line 49. The communication line 49 is used for communicating various information such as commands, status, and data.

[0052] (5) Structure of Compressor 11 Fig. 3 shows a cross section of the compressor 11. The compressor 11 includes a compressor housing 71, a motor 72, a crankshaft 73, a compression mechanism 74, and a terminal portion 75.

[0053] (5-1) Compressor Housing 71 The compressor housing 71 is a container that houses the components of the compressor 11. Furthermore, the compressor housing 71 houses the refrigerant 65 and refrigeration oil. The compressor housing 71 has an upper part 711, a cylindrical part 712, and a lower part 713 that are hermetically welded together, and has a structure that can withstand the high pressure of the refrigerant 65.

[0054] The compressor housing 71 is provided with the aforementioned suction pipe 112 and discharge pipe 111. The suction pipe 112 is provided below the cylindrical portion 712. The discharge pipe 111 is provided in the upper portion 711.

[0055] (5-2) Motor 72 The motor 72 is a device that receives a supply of electric power and generates power to drive the compression mechanism 74. The motor 72 is provided above the cylindrical portion 712. The motor 72 has a stator 721 fixed to the compressor housing 71 and a rotor 725 that is rotatably installed.

[0056] The stator 721 has a stator core 722 made of laminated steel plates, an insulator 723 made of resin, and a coil 724. The coil 724 is a winding wound around the stator core 722 and the insulator 723. The coil 724 generates an AC magnetic field.

[0057] The rotor 725 has a rotor core 726 made of laminated steel plates, as well as permanent magnets and end plates (not shown). The permanent magnets interact with the AC magnetic field generated by the coils 724, causing the entire rotor 725 to rotate. The end plates prevent the permanent magnets, which are installed in cavities in the rotor core 726, from falling out.

[0058] (5-3) Crankshaft 73 The crankshaft 73 transmits the rotational force generated by the motor 72 to the compression mechanism 74 .

[0059] (5-4) Compression Mechanism 74 The compression mechanism 74 is provided below the cylindrical portion 712 and is connected to the suction pipe 112. The compression mechanism 74 has a cylinder 741, a piston 742, and a muffler 744. The cylinder and piston 742 define a compression chamber 743. The piston 742 revolves due to the rotation of the crankshaft 73, causing the volume of the compression chamber 743 to vary. As a result, the refrigerant 65 in a low-pressure gas state that is sucked from the suction pipe 112 is compressed and becomes a high-pressure gas state. The muffler 744 reduces pressure pulsation of the refrigerant 65 in the high-pressure gas state, thereby reducing noise. The refrigerant 65 that leaves the muffler passes upward through the gaps in the motor 72 (for example, the gap between the stator 721 and the rotor 725, the core cut provided between the stator 721 and the cylindrical portion 712, and the gap between adjacent coils 724 in the stator 721, etc.), and is then discharged out of the compressor 11 from the discharge pipe 111.

[0060] (5-5) Terminal Unit 75 The terminal unit 75 takes in externally supplied power into the compressor 11. The terminal unit 75 has a terminal pin 751, a terminal base 752, a lead wire 753, and a terminal guard 754. The terminal pin 751 is a terminal for connecting an external electric wire. The terminal base 752 is a member for attaching the terminal pin 751 to the compressor housing 71. The lead wire 753 connects the terminal pin 751 to the coil 724 of the motor 72. The terminal guard 754 is provided on the surface of the compressor housing 71 and surrounds the terminal pin 751 to prevent damage to the terminal pin 751.

[0061] (5-6) Protection Circuit If a short circuit occurs in the electric circuit of the compressor 11, the protection circuit cuts off the current. The protection circuit includes an inverter protection device and a non-inverter sine wave breaker.

[0062] The inverter protection device is mounted on the heat source control unit 19. The inverter protection device has a current detection means such as a shunt resistor. When a current value exceeding a threshold is detected in the inverter output current, the inverter protection device stops the inverter output current.

[0063] The non-inverter sine wave breaker is mounted on a distribution panel in the commercial power supply 47. The non-inverter sine wave breaker has a ZTC (zero-phase-sequence current transformer), a ground fault relay, and a circuit breaker. When a ground fault occurs, the non-inverter sine wave breaker stops the power supply from the commercial power supply 47 to the refrigeration device 90.

[0064] (6) Grounding Path (6-1) Heat Source Unit 10 FIG. 4 is a schematic diagram of the structure of the heat source unit 10. As shown in FIG.

[0065] The heat source housing 105 is in communication with the liquid shutoff valve 17 and the gas shutoff valve 18. The liquid shutoff valve 17 and the gas shutoff valve 18 are in communication with part of the four-way switching valve 12, part of the accumulator 16, the compressor housing 71, part of the heat source expansion valve 15, and the heat source heat exchanger 13 via internal piping T1 to T7.

[0066] The grounding wire 51 is a conductor that connects the heat source housing 105 to the ground G, and has the function of guiding the discharge energy generated inside the heat source unit 10 to the ground G. An embedded portion 53 is buried in the ground G that grounds the heat source unit 10. The embedded portion 53 is connected to the liquid shut-off valve 17 by the grounding wire 51. The grounding wire 51 forms a grounding path that connects the heat source housing 105 to the ground G.

[0067] A grounding resistor 55 is connected to the grounding wire 51. The grounding resistor 55 consumes the electrical energy flowing through the grounding wire 51 and converts it into thermal energy. The grounding resistor 55 may be, for example, an electronic component physically connected to the grounding wire 51, or may be a grounding resistor.

[0068] The heat source power supply unit 45 and the heat source control unit 19 that constitute the electrical system 40 are housed in an electrical equipment box 48. As shown in Figure 4, by appropriately installing the electrical equipment box 48, a conductive path 59 is formed between the ground potential GND of the electrical system 40 and the heat source housing 105. Due to the presence of the conductive path 59, the ground potential GND of the electrical system 40 is also conductive with the ground wire 51 and the earth G.

[0069] (6-2) Utilization Unit 20 As shown in Fig. 1, the utilization heat exchanger 23 is electrically connected to a grounding wire 95 extending to the outside of the utilization housing 205. A grounding resistor 94 is connected in series to the grounding wire 95. The grounding resistor 94 may be, for example, an electronic component physically connected to the grounding wire 95, or may be a grounding resistor.

[0070] The outlet of the commercial power supply 47 has a first power terminal 91, a second power terminal 92, and a ground terminal 93. The ground terminal 93 is electrically connected to a buried portion 96 buried in the ground. A ground wire 95 of the utilization unit 20 is connected to the ground terminal 93. The ground terminal 93 is connected to the utilization heat exchanger 23 via a ground resistor 94.

[0071] (7) Mechanism of Disproportionation Reaction The applicants have discovered that a disproportionation reaction is induced when discharge energy is applied to the refrigerant 65. The disproportionation reaction is expressed by the following chemical formula:

[0072] As can be seen from this chemical formula, in the disproportionation reaction, the aforementioned component 1 (1,2-difluoroethylene, HFO-1132) in refrigerant 65 is decomposed and heat is generated. This heat generation induces further decomposition of unreacted refrigerant, causing a chain reaction of decomposition. If this occurs in the housing of refrigeration device 90, a rapid pressure rise can occur in a short period of time.

[0073] (8) Discharge Inside the Compressor 11 Figure 5 shows discharge locations S1, S2, and S3 inside the compressor 11 where discharge is likely to occur. Discharge location S1 is between the terminal pin 751 and the compressor housing 71. The compressor housing 71 here includes the portion of the terminal base 752 that is electrically connected to the compressor housing 71 and the terminal guard 754. Discharge location S2 is between the lead wire 753 and the compressor housing 71. Discharge location S3 is between the coil 724 and the stator core 722. The stator core 722 is electrically connected to the compressor housing 71. Discharges that are relatively likely to occur at discharge locations S1 to S3 can induce disproportionation reactions.

[0074] The discharge energy in the compressor can be calculated according to a model 80 shown in FIG. 6 . The model 80 is a closed-loop circuit in which a DC power supply 81, a resistor 82, and a movable contact 83 are connected in series. The potential difference between both terminals of the DC power supply 81 is the contact voltage E (V). The resistor 82 has a resistance value R (Ω). This resistor 82 in the model 80 is used to simulate the grounding resistor 55 or the grounding resistor 94 in the refrigeration device 90. The discharge duration T (s) of the movable contact 83 can be set by changing the distance between the contacts. The magnitude of the current flowing through the movable contact 83 is the short-circuit current I (A). When the discharge duration is T (s), the discharge energy Dis. E (J) generated at the movable contact 83 can be calculated using the following formula:

[0075] where the variables and constants are as follows: Dis. E (J): Discharge energy E (V): Power supply voltage of the circuit I (A): Short-circuit current R (Ω): Resistance value T (s): Discharge duration Varc (V): Voltage between contacts at the arc occurrence point Iarc (A): Short-circuit current at the time of arc occurrence Em: Parameter determined by contact material Im: Parameter determined by contact material

[0076] FIG. 7 is a graph plotting the discharge energy Dis. E (J) calculated using the above formula when the discharge duration T (s) and resistance value R (Ω) are changed, on a logarithmic scale. Reference periods P1 to P3 are indicated on the horizontal axis, which indicates the discharge duration T (s). Period P1 is the time interval from the start of discharge to the start of operation of the inverter protection device. During period P1, the inverter protection device operates, causing the compressor 11 to stop. During period P2, the voltage supplied to the motor 72 becomes a square wave. Period P3 is the period during which the non-inverter sine wave earth leakage breaker operates. After period P3 has elapsed, power supply to the refrigeration device 90 is stopped. Period P3, which is the latest period from the start of discharge, may result in the longest discharge duration T (s). The end of period P3, 10 ms after the start of discharge, is considered to be the longest discharge duration T (s).

[0077] (9) Presence or absence of disproportionation reaction Fig. 8 is a graph showing the disproportionation occurrence boundary line at each discharge energy Dis. E (J) when the content (mass%) of HFO-1132 in refrigerant 65 and pressure P (MPa) are changed. For example, when the discharge energy Dis. E (J) is 3 (J), a disproportionation reaction occurs in region A1 in the figure, but does not occur in region A2.

[0078] As examples of conditions under which the disproportionation reaction does not occur, the first to third conditions will be explained below.

[0079] (9-1) First Condition The first condition is the shaded area shown in Figures 9 and 10. Figures 9 and 10 are obtained by adding shaded areas and the like to Figures 7 and 8, respectively.

[0080] The first condition is R≧0.1 (Ω), ... Figure 9 E≦1000 (J), ... Figures 9 and 10 A≦32 (mass%), and ... Figure 10 P≦6 (MPa), ... Figure 10.

[0081] (9-2) Second Condition The second condition is the shaded area shown in Figures 11 and 12. Here, Figures 11 and 12 are Figures 7 and 8, respectively, with shaded areas and the like added.

[0082] The second condition is R≧1.0 (Ω), ... Figure 11 E≦250 (J), ... Figure 11, Figure 12 A≦45 (mass%), and ... Figure 12 P≦2 (MPa), ... Figure 12.

[0083] (9-3) Third Condition The third condition is the shaded area shown in Figures 13 and 14. Here, Figures 13 and 14 are Figures 7 and 8 to which shaded areas and the like have been added, respectively.

[0084] The third condition is R≧10.0 (Ω), ... Figure 13 E≦30 (J), ... Figure 13, Figure 14 A≦55 (mass%), and ... Figure 14 P≦1 (MPa), ... Figure 14.

[0085] (10) Features (10-1) When discharge energy Dis. E(J) that may cause a disproportionation reaction of the refrigerant 65 occurs inside the refrigeration device 90, the discharge energy Dis. E(J) can be consumed by the grounding resistor 55. Therefore, the disproportionation reaction of the refrigerant 65 can be suppressed in the refrigeration device 90.

[0086] (10-2) Discharge energy that may induce a disproportionation reaction of the refrigerant 65 inside the refrigeration device 90 propagates through the grounding wire 51 that is electrically connected to the compressor housing 71 and is consumed by the grounding resistor 55. Therefore, the disproportionation reaction of the refrigerant 65 is suppressed.

[0087] (10-3) Discharge energy that may induce a disproportionation reaction of the refrigerant 65 inside the refrigeration device 90 propagates through the grounding wire 95 that is electrically connected to the utilization heat exchanger 23, and is consumed by the grounding resistor 94. Therefore, the disproportionation reaction of the refrigerant 65 is suppressed.

[0088] (10-4) When a break occurs in one of the two grounding wires, namely, the grounding wire 51 and the grounding wire 95, the discharge energy propagates to the other and is consumed by the grounding resistor 55 or the grounding resistor 94. Therefore, the disproportionation reaction of the refrigerant 65 is more reliably suppressed.

[0089] (10-5) Refrigerant 65 contains HFO-1132. Therefore, the disproportionation reaction of HFO-1132, which is prone to disproportionation, can be suppressed. Refrigerant 65 may further contain HFO-1134yf. Since refrigerant 65 contains HFO-1134yf, the flammability of refrigerant 65 can be reduced.

[0090] (10-6) The grounding resistors 55 and 94 can sufficiently consume the discharge energy generated inside the refrigeration device 90. Therefore, the disproportionation reaction can be suppressed in the refrigerant composition defined by "A" of the first to third conditions.

[0091] (10-7) The ground resistors 55 and 94 are physically connected to the ground wires 51 and 95, and do not require any modification to the inside of the housing, so they do not take up space inside the housing.

[0092] <Modifications of the above embodiment> (11) Modifications (11-1) Modification A In the above embodiment, a grounding resistor 55 is provided in the grounding wire 51 of the heat source unit 10, and a grounding resistor 94 is also provided in the grounding wire 95 of the utilization unit 20. Alternatively, only one of the grounding resistor 55 in the grounding wire 51 or the grounding resistor 94 in the grounding wire 95 may be provided.

[0093] (11-2) Modification B The conductive path 59 that connects the ground potential GND of the electrical system 40 to the heat source housing 105 does not necessarily have to exist. In other words, the ground potential GND may be insulated from the heat source housing 105.

[0094] (11-3) Modification C The configuration of the electrical system 40 is not limited to that described above. For example, the heat source power supply unit 45 may have a regulator and generate the power supply voltage V2 by itself. The heat source power supply unit 45 may also receive power from the commercial power supply 47. The number of power lines 41 is not limited to two, the first power line 41a and the second power line 41b, but may be one or three or more.

[0095] (11-4) Modification D The ground resistor 55 may be disposed inside the heat source housing 105. For example, the ground resistor 55 may be mounted on the circuit board of the electrical component box 48.

[0096] (11-5) Modification E The refrigeration device 90 of the above embodiment has a heat source unit 10 and a utilization unit 20 that are separate from each other. Alternatively, the refrigeration device 90 may be configured as a single unit in which the heat source unit 10 and the utilization unit 20 share the same housing.

[0097] <Conclusion> Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims.

[0098] 10: Heat source unit 11: Compressor 17: Liquid stop valve 18: Gas stop valve 19: Heat source control unit 20: User unit 23: User heat exchanger 29: User control unit 30: Connecting piping group 40: Electrical system 41: Power line 41a: First power line 41b: Second power line 42: Ground line 43: Cable 45: Heat source power supply unit (power supply unit) 46: User power supply unit 47: Commercial power supply 48: Electrical equipment box 49: Communication line 51: Ground line (first ground line) 53: Buried part 55: Ground resistor (first ground resistor) 59: Conduction path 60: Refrigerant circuit 61: Heat source refrigerant circuit (refrigerant circuit) 62: User refrigerant circuit (refrigerant circuit) 65: Refrigerant 71: Compressor housing 72: Motor 73: Crankshaft 74: Compression mechanism 75: Terminal section 90: Refrigeration device 94: Grounding resistor (second grounding resistor) 95: Grounding wire (second grounding wire) 105: Heat source housing (housing) 111: Discharge pipe 112: Suction pipe 205: Usage housing (housing) 711: Upper section 712: Cylindrical section 713: Lower section 721: Stator 722: Stator core 723: Insulator 724: Coil 725: Rotor 726: Rotor core 751: Terminal pin 752: Terminal base 753: Lead wire 754: Terminal guard G: Ground GND: Ground potential E: Voltage between contacts I: Short-circuit current T: Discharge duration A (mass%): refrigerant composition ratio Dis. E (J): discharge energy P (MPa): pressure R (Ω): resistance value

[0099] International Publication No. WO2018 / 168776

Claims

1. A refrigeration device (90) comprising: a housing (105; 205); a refrigerant circuit (60; 61; 62) that circulates a refrigerant (65) capable of causing a disproportionation reaction; a power supply unit (45; 46) that receives power from a commercial power supply (47); a grounding wire (51; 95) that connects the housing to a ground (G) outside the housing; and a grounding resistor (55; 94) that is connected to the grounding wire and has a resistance value of 0.1 Ω or more.

2. The refrigeration system according to claim 1, further comprising a compressor (11) having a compressor housing (71), and the ground wire (51) is electrically connected to the compressor housing.

3. The refrigeration apparatus according to claim 1 or 2, further comprising a utilization heat exchanger (23), and the ground wire (95) is electrically connected to the utilization heat exchanger.

4. The refrigeration apparatus of claim 1, further comprising: a compressor (11) having a compressor housing (71); and a utilization heat exchanger (23), wherein the grounding resistor comprises: a first grounding resistor (55) and a second grounding resistor (94), and the grounding wire comprises: a first grounding wire (51) that is conductive to the first grounding resistor and the compressor housing, and a second grounding wire (95) that is conductive to the second grounding resistor and the utilization heat exchanger.

5. A refrigeration system as claimed in any one of claims 1 to 4, wherein the refrigerant (65) comprises 1,2-difluoroethylene (HFO-1132).

6. The refrigeration system of claim 5, wherein the refrigerant (65) further comprises 2,3,3,3-tetrafluoropropene (HFO-1234yf).

7. The resistance value of the earth resistor (55; 94) is R (Ω), the ratio of the 1,2-difluoroethylene (HFO-1132) in the refrigerant (65) is A (mass%), and the discharge energy applied to the refrigerant is Dis.

7. The refrigeration apparatus according to claim 6, wherein: R≧0.1 (Ω), E≦1000 (J), A≦32 (mass%), and P≦6 (MPa); the pressure when the refrigerant is used is P (MPa); and any of a first condition, a second condition, and a third condition is satisfied; the first condition is R≧1.0 (Ω), E≦250 (J), A≦45 (mass%), and P≦2 (MPa); and the third condition is R≧10.0 (Ω), E≦30 (J), A≦55 (mass%), and P≦1 (MPa).

8. A refrigeration system according to any one of claims 1 to 7, wherein the earth resistor (55; 94) is physically connected to the earth wire (51; 95).

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