Refrigeration equipment

Abstract

This technology provides a way to properly capture acids generated by odor components in the refrigerant circuit, thereby ensuring the reliability of the refrigerant and odor components in the refrigerant circuit. [Solution] The air conditioning system 1, which is a refrigeration system, comprises a compressor 21, an outdoor heat exchanger 22 which is a condenser, an expansion mechanism 23, an indoor heat exchanger 31 which is an evaporator, and a refrigerant circuit 10 for circulating refrigerant and refrigerant oil. The expansion mechanism 23 has an expansion valve including metal parts. The refrigerant contains hydrocarbons having 1 to 4 carbon atoms. The refrigerant oil is polyalkylene glycol and contains 0.1% to 2.0% by weight of an acid scavenger relative to the refrigerant oil. The amount of sulfur-based odor components filled relative to the amount of refrigerant filled is 50 ppm to 2000 ppm by weight.

Description

Technical Field

[0001] The present disclosure relates to a refrigeration device.

Background Art

[0002] Conventionally, a refrigeration device in which a strongly flammable refrigerant is enclosed in a refrigerant circuit as a refrigerant having a low Global Warming Potential (GWP) value, which is a global warming coefficient, is known. For this type of refrigeration device, it is important to recognize the leakage of the refrigerant from the refrigerant circuit at an early stage and avoid the combustion of the refrigerant.

[0003] Patent Document 1 discloses a refrigeration cycle device in which, in addition to the refrigerant, an odor component which is a sulfur-based deodorant is enclosed in the refrigerant circuit. Along with the leakage of the refrigerant from the refrigerant circuit, the odor component also leaks, enabling people around to recognize the abnormality and take necessary measures.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, a part of the odor component filled in the refrigerant circuit decomposes inside the refrigerant circuit to generate an acid. The generated acid becomes a factor for corroding, for example, the metal parts of the refrigerant circuit.

[0006] Therefore, since the acid scavenger affects the dissolution of the refrigerant and the refrigeration oil and the viscosity of the refrigerant, etc., it is necessary to fill the refrigerant circuit with an appropriate amount.

[0007] The present disclosure provides a technique capable of appropriately capturing an acid generated by an odor component in a refrigerant circuit and ensuring the reliability of the refrigerant and the odor component in the refrigerant circuit.

Means for Solving the Problems

[0008] According to one aspect of the present disclosure, a refrigeration system comprising a compressor, a condenser, an expansion mechanism, an evaporator, and a refrigerant circuit for circulating a refrigerant and refrigerant oil, wherein the expansion mechanism has an expansion valve including metal parts, the refrigerant comprises a hydrocarbon having 1 to 4 carbon atoms, the refrigerant oil is polyalkylene glycol, and contains 0.1% to 2.0% by weight of an acid scavenger relative to the refrigerant oil, and the amount of sulfur-based odor components filled relative to the amount of refrigerant filled is 50 ppm to 2000 ppm by weight.

[0009] According to the above, the 50% to 2000% by weight of odor components packed into the refrigerant circuit can sufficiently increase the remaining percentage of the 0.1% to 2.0% by weight of acid scavenger added to the refrigerant oil. This makes it possible to effectively capture any acid generated by the decomposition of odor components in the refrigerant circuit using the acid scavenger.

[0010] Furthermore, the acid scavenger is present in an amount of 0.3% to 1.0% by weight relative to the refrigeration oil.

[0011] This allows the refrigeration system to fill the refrigerant circuit 10 with an amount of acid scavenging agent sufficient to capture the acid in the refrigerant circuit 10 while ensuring the lubrication of the refrigerant oil.

[0012] Furthermore, the amount of air mixed with the refrigerant oil in the refrigerant circuit is 500 ppm by weight or less.

[0013] This allows the refrigeration system to capture acid in the air mixed into the refrigerant circuit using an acid scavenger, thereby reducing the amount of acid in the refrigerant circuit.

[0014] Furthermore, the amount of water mixed into the refrigerant circuit with respect to the refrigerant oil is 200 ppm by weight or less.

[0015] This allows the refrigeration system to capture the acid generated from water mixed into the refrigerant circuit using an acid scavenger, thereby reducing the amount of acid in the refrigerant circuit.

[0016] Further, when the concentration of the refrigerating oil contained in the mixture of the refrigerant and the refrigerating oil is 40% by weight or more, the refrigerating oil is an oil in which the refrigerant and the refrigerating oil are soluble.

[0017] Thereby, in the refrigeration device, the refrigerant and the refrigerating oil are dissolved in the refrigerant circuit, so that the refrigerating oil can be circulated well.

[0018] Further, the refrigerating oil further contains an extreme pressure agent.

[0019] Thereby, the refrigeration device can appropriately avoid wear and seizure in the compressor of the refrigerant circuit.

[0020] Further, the refrigerating oil further contains an antioxidant.

[0021] Thereby, the refrigeration device can reduce the oxidation of the refrigerating oil itself.

[0022] Further, the discharge gas temperature of the refrigerant discharged from the compressor is controlled to 120°C or less.

[0023] Thereby, the refrigeration device can keep the temperatures of the refrigerant, the odor component, and the refrigerating oil low, and can suppress the decomposition of the odor component and the like.

[0024] Further, the refrigerant is a strongly flammable refrigerant.

[0025] Thereby, the refrigeration device can fill the refrigerant circuit with a refrigerant having a low GWP value and perform heat exchange by the refrigerant well in the condenser and the evaporator. Moreover, since the filling amount of the odor component is 50% by weight to 2000% by weight as described above, when the odor component leaks together with the refrigerant, it is possible to stably promote repellent induction to people.

[0026] Further, the odor component is selected from the group consisting of sulfides and thiophenes.

[0027] This helps to suppress the significant reduction of the acid scavenger caused by odor components filling the refrigerant circuit.

[0028] Furthermore, the odor component is tetrahydrothiophene.

[0029] This allows odor components to suppress the reduction of the acid scavenging agent while also enabling people to recognize abnormalities in the refrigerant circuit when a leak occurs.

[0030] Furthermore, the odor component is dimethyl sulfide.

[0031] Even in this case, the odor components can suppress the decrease of the acid scavenging agent while allowing people to recognize an abnormality in the refrigerant circuit leak.

[0032] Furthermore, the odor component is ethyl methyl sulfide.

[0033] Even in this case, the odor components can suppress the decrease of the acid scavenging agent while allowing people to recognize an abnormality in the refrigerant circuit leak.

[0034] Furthermore, the viscosity of the mixture containing the refrigerant oil and the acid scavenger at 40°C is 5 cSt to 300 cSt.

[0035] Thus, by having a viscosity of 5 cSt to 300 cSt between the refrigerant oil and the acid scavenger, the refrigerant oil to which the acid scavenger has been added can be circulated smoothly in the refrigerant circuit.

[0036] Furthermore, the refrigerant oil has a volume resistivity of 1 × 10 at 40°C. 6 It is greater than or equal to Ω·m.

[0037] Thus, the volume resistivity of the refrigerant oil is 1 × 10⁻⁶ 6 By having a resistance of Ω·m or higher, electrical insulation is ensured, and current leakage from electrical components such as motor windings inside the compressor to the outside of the refrigerant circuit through the refrigerant oil can be suppressed.

[0038] Furthermore, the refrigeration device is an air conditioning device, a hot water supply device, or a cooling water circulation device.

[0039] As a result, air conditioning systems, hot water supply systems, or cooling water circulation systems can ensure a sufficient amount of acid scavenging agent in the refrigerant circuit during operation, thereby reducing the occurrence of metal corrosion and other issues. [Brief explanation of the drawing]

[0040] [Figure 1] This diagram schematically shows the configuration of an air conditioning system according to an embodiment. [Figure 2] This graph shows the relationship between the amount of odor components filled into the refrigerant circuit and the remaining percentage of acid scavenging agent in the refrigerant circuit. [Figure 3] This table shows the results of checking the amount of odor components filled into the refrigerant circuit, the residual rate of the acid scavenger, and metal corrosion. [Modes for carrying out the invention]

[0041] The embodiments for implementing this disclosure will be described below with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant explanations may be omitted. In addition, dimensions, ratios, or numbers in each drawing may be exaggerated or simplified as necessary to facilitate understanding of this disclosure.

[0042] <Configuration of the refrigeration system> As shown in Figure 1, the refrigeration system 1 according to the embodiment of this disclosure is an air conditioning system that adjusts the temperature of the air in a living space LS. Hereinafter, the refrigeration system 1 will also be referred to as the air conditioning system 1. The air conditioning system 1 is used for cooling and heating operations of the living space LS by operating a vapor compression type refrigeration cycle. In cooling operation, the air conditioning system 1 cools the air in the living space LS to adjust its temperature. In heating operation, the air conditioning system 1 heats the air in the living space LS to adjust its temperature.

[0043] The air conditioning system 1 includes a refrigerant circuit 10 filled with refrigerant, an outdoor unit 20 which is a heat source unit installed in the outdoor space, and an indoor unit 30 which is a utilization unit installed in the living space LS. The refrigerant circuit 10 performs cooling and heating operations by circulating the refrigerant between the outdoor unit 20 and the indoor unit 30. The air conditioning system 1 according to this embodiment is a pair type in which one outdoor unit 20 and one indoor unit 30 are connected. However, the air conditioning system 1 may also be configured in which one outdoor unit 20 and multiple indoor units 30 are connected, or in which multiple outdoor units 20 and one indoor unit 30 are connected.

[0044] The refrigerant circuit 10 includes a first connecting pipe 11 and a second connecting pipe 12 that connect the outdoor unit 20 and the indoor unit 30. The first connecting pipe 11 and the second connecting pipe 12 connect the living space LS and the outdoor space and circulate the refrigerant. The first connecting pipe 11 is one or more gas pipes that circulate the refrigerant in gaseous form. The second connecting pipe 12 is one or more liquid pipes that circulate the refrigerant in liquid form.

[0045] Furthermore, the refrigerant circuit 10 has an outdoor route 13 inside the outdoor unit 20 that is connected to one end of the first connecting pipe 11 and one end of the second connecting pipe 12, respectively. In addition, the refrigerant circuit 10 has an indoor route 14 inside the indoor unit 30 that is connected to the other end of the first connecting pipe 11 and the other end of the second connecting pipe 12, respectively. The refrigerant circuit 10 forms an endless circulation circuit with the first connecting pipe 11, the second connecting pipe 12, the outdoor route 13, and the indoor route 14.

[0046] <Outdoor unit> The outdoor unit 20 constitutes a part of the refrigerant circuit 10 by having an outdoor passage 13 installed inside the housing 20a. The outdoor unit 20 includes a compressor 21, an outdoor heat exchanger 22, an expansion mechanism 23, a four-way switching valve 24, and an outdoor fan 25. The compressor 21, outdoor heat exchanger 22, expansion mechanism 23, and four-way switching valve 24 are connected to the outdoor passage 13 of the outdoor unit 20.

[0047] In refrigeration cycle operation, the compressor 21 compresses the low-pressure refrigerant drawn in from the suction connection terminal 21i to a high pressure and discharges the high-pressure refrigerant from the discharge connection terminal 21o. As the compressor 21, for example, a rotary type device can be used that rotates a sealed compression element with a compressor motor 21m to pressurize the refrigerant. The suction connection terminal 21i and the discharge connection terminal 21o of the compressor 21 are connected to the four-way switching valve 24 through the outdoor passage 13.

[0048] The outdoor heat exchanger 22 is a heat source-side heat exchanger (condenser) that dissipates heat from the refrigerant by exchanging heat between the refrigerant circulating inside and the outdoor air during refrigeration cycle operation in cooling operation. For example, a fin-and-tube type mechanism can be applied to this outdoor heat exchanger 22. The gas connection terminal 22G of the outdoor heat exchanger 22 is connected to the four-way switching valve 24 through the outdoor passage 13. The liquid connection terminal 22L of the outdoor heat exchanger 22 is connected to the expansion mechanism 23 through the outdoor passage 13.

[0049] The outdoor fan 25 blows outdoor air to the outdoor heat exchanger 22. For example, the outdoor fan 25 can be a propeller fan having a motor and propeller (not shown).

[0050] The expansion mechanism 23 is a pressure reducing device that reduces the pressure of the refrigerant flowing in through the outdoor passage 13 to lower its temperature. The expansion mechanism 23 includes an electronic expansion valve or a temperature-sensitive expansion valve that adjusts the opening of the internal flow path. The expansion valve includes metal parts that are exposed in the part through which the refrigerant and odor components flow. Examples of metal materials for the metal parts include copper, iron, and aluminum. The expansion mechanism 23 may also be installed in the indoor unit 30.

[0051] The four-way switching valve 24 reverses the flow of refrigerant in the refrigerant circuit 10 to selectively perform cooling and heating operations. This four-way switching valve 24 can be switched between a first state, shown by the solid line in Figure 1, and a second state, shown by the dashed line in Figure 1.

[0052] The four-way diverter valve 24 is provided with a first port 241, a second port 242, a third port 243, and a fourth port 244 to which multiple pipes constituting the refrigerant circuit 10 can be connected. The discharge connection end 21o of the compressor 21 is connected to the first port 241 of the four-way diverter valve 24 via the piping of the outdoor route 13. The gas connection end 22G of the outdoor heat exchanger 22 is connected to the second port 242 of the four-way diverter valve 24 via the piping of the outdoor route 13. The piping of the outdoor route 13 that connects to the first connecting pipe 11 is connected to the third port 243 of the four-way diverter valve 24. The third port 243 is connected to the gas connection end 31G of the indoor heat exchanger 31 via the first connecting pipe 11. The suction connection end 21i of the compressor 21 is connected to the fourth port 244 of the four-way diverter valve 24 via the piping of the outdoor route 13.

[0053] As shown by the solid line in Figure 1, the four-way diverter valve 24 can form a first state in which the first port 241 and the second port 242 are in communication, and the third port 243 and the fourth port 244 are in communication. In this first state, the four-way diverter valve 24 connects the discharge connection end 21o of the compressor 21 and the gas connection end 22G of the outdoor heat exchanger 22, while connecting the suction connection end 21i of the compressor 21 and the first connecting pipe 11 outside the outdoor unit 20. In this first state, based on the drive of the compressor 21, refrigerant flows from the first connecting pipe 11 into the outdoor path 13 of the outdoor unit 20. The refrigerant is compressed by the compressor 21 to a high pressure and moves to the outdoor heat exchanger 22 through the four-way diverter valve 24. The refrigerant releases heat in the outdoor heat exchanger 22 and is further depressurized in the expansion mechanism 23, becoming a low-pressure, low-temperature liquid, which then moves to the second connecting pipe 12. In other words, the air conditioning unit 1 can perform cooling operation by drawing in high-temperature refrigerant via the first connecting pipe 11 and sending low-temperature refrigerant to the indoor unit 30 via the second connecting pipe 12.

[0054] Furthermore, the four-way switching valve 24 can form a second state in which the first port 241 and the third port 243 are in communication, and the second port 242 and the fourth port 244 are in communication, as shown by the dotted line in Figure 1. In this second state, the four-way switching valve 24 connects the discharge connection end 21o of the compressor 21 to the first connecting pipe 11 outside the outdoor unit 20, while connecting the suction connection end 21i of the compressor 21 to the gas connection end 22G of the outdoor heat exchanger 22. In this second state, refrigerant flows from the second connecting pipe 12 into the outdoor path 13 of the outdoor unit 20 based on the drive of the compressor 21. The refrigerant moves to the outdoor heat exchanger 22 through the expansion mechanism 23, and then moves from the outdoor heat exchanger 22 to the compressor 21. The refrigerant is compressed in the compressor 21 to become a high-pressure, high-temperature gas, which then moves to the first connecting pipe 11 through the four-way switching valve 24. In other words, the air conditioning system 1 can perform heating operation by drawing in low-temperature refrigerant through the second connecting pipe 12 and sending high-temperature refrigerant to the indoor unit 30 through the first connecting pipe 11.

[0055] Furthermore, the outdoor path 13 of the outdoor unit 20 can be divided into a gas line 13G that mainly circulates the refrigerant in gaseous form, and a liquid line 13L that mainly circulates the refrigerant in liquid form. The gas line 13G is the path connecting from the connection point with the first connecting pipe 11 to the compressor 21 and the gas connection terminal 22G of the outdoor heat exchanger 22. The liquid line 13L is the path connecting from the connection point with the second connecting pipe 12 to the expansion mechanism 23 and the liquid connection terminal 22L of the outdoor heat exchanger 22.

[0056] A first shut-off valve 41 is provided at the connection point between the gas line 13G and the first connecting pipe 11. The first shut-off valve 41 opens and closes the flow path of the gas line 13G based on the operator's operation. A second shut-off valve 42 is provided at the connection point between the liquid line 13L and the second connecting pipe 12. The second shut-off valve 42 opens and closes the flow path of the liquid line 13L based on the operator's operation.

[0057] Furthermore, the first shut-off valve 41 has a gas service port 44. The second shut-off valve 42 has a liquid service port 45. The first shut-off valve 41 is larger than the second shut-off valve 42. The gas service port 44 and the liquid service port 45 are used when filling the refrigerant circuit 10 of the air conditioner 1 with refrigerant, when releasing refrigerant from the outdoor unit 20, when measuring the refrigerant pressure in the refrigerant circuit 10, etc.

[0058] <Indoor unit> Meanwhile, the indoor unit 30 is installed in the living space LS. The indoor unit 30 constitutes a part of the refrigerant circuit 10 by having an indoor path 14 inside the housing 30a. The indoor unit 30 includes an indoor heat exchanger 31 and an indoor fan 32. The indoor heat exchanger 31 is connected to the indoor path 14 of the indoor unit 30.

[0059] The indoor heat exchanger 31 is a user-side heat exchanger (evaporator) that performs heat exchange between the refrigerant circulating inside and the indoor air during refrigeration cycle operation. As a result, the indoor heat exchanger 31 can cool the indoor air by absorbing heat from it when the refrigerant is at a lower temperature than the indoor air, and can warm the indoor air by releasing heat when the refrigerant is at a higher temperature than the indoor air. For example, a fin-and-tube mechanism can be applied to this indoor heat exchanger 31. The gas connection terminal 31G of the indoor heat exchanger 31 is connected to the first connecting pipe 11 through the indoor passage 14. The liquid connection terminal 31L of the indoor heat exchanger 31 is connected to the second connecting pipe 12 through the indoor passage 14.

[0060] The indoor fan 32 blows indoor air to the indoor heat exchanger 31. The indoor fan 32 is, for example, a cross-flow fan having a motor and a cylindrical impeller (not shown). The indoor air carried by the indoor fan 32 passes through the indoor heat exchanger 31 and is then blown from the indoor heat exchanger 31 into the living space LS.

[0061] Furthermore, the indoor unit 30 has a power circuit connected to the commercial power supply. The air conditioning system 1 operates the indoor unit 30 based on the power supply from the commercial power supply, and also operates the outdoor unit 20 via power lines (not shown).

[0062] <Control unit for air conditioning system> The air conditioning system 1 has a control unit 90 that controls the operation of each component. The control unit 90 is composed of a first control device 91, a second control device 92, and a remote controller 93. The remote controller 93 is a device that allows a person (user) to operate various instructions to the air conditioning system 1, and may be a dedicated controller or a mobile terminal such as a smartphone or tablet.

[0063] Each of the first control unit 91, the second control unit 92, and the remote controller 93 is a computer (specifically, an MCU: Micro Control Unit) having a processor, memory, input / output interface, and communication interface. The processor is a combination of one or more of the following: CPU (Central Processing Unit), GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or a circuit consisting of multiple discrete semiconductors. The memory includes non-volatile memory and volatile memory. Programs that control various processes are stored in the memory, and the processor controls various operations by reading and executing the programs stored in the memory.

[0064] The first control device 91 is installed in the outdoor unit 20 and controls the various components of the outdoor unit 20. The second control device 92 is installed in the indoor unit 30 and controls the various components of the indoor unit 30. The first control device 91 and the second control device 92 can send and receive information from each other via wired or wireless communication. The second control device 92 and the remote controller 93 can send and receive information from each other via wired or wireless communication. The control unit 90 selectively performs cooling operation and heating operation in response to operation commands from a person (user) to the remote controller 93.

[0065] <Refrigerant> The refrigerant sealed in the refrigerant circuit 10 should be selected to have the lowest possible GWP value and low environmental impact. Examples of materials for this type of refrigerant include hydrocarbons (hydrocarbons) with 1 to 4 carbon atoms, such as R290 (propane), R1270 (propylene), and R600a (isobutane). These refrigerant materials are highly flammable refrigerants with higher flammability than hydrofluorocarbons. In this embodiment, the case where propane is used as the refrigerant will be described. Note that the refrigerant may also be methane (R50), ethane (R170), butane (R600), ammonia (R717), etc.

[0066] <Odor components> As previously described, the air conditioning system 1 contains an odor component along with the refrigerant in order to allow people to detect leaks of highly flammable refrigerant from the refrigerant circuit 10. Examples of this odor component include sulfur-based compounds such as sulfur-based odorants. It is more preferable that this sulfur-based odorant be selected from the group consisting of sulfides and thiophenes. For example, the odor component may be a thiophene-based odorant such as tetrahydrothiophene (THT), a sulfide-based odorant such as dimethyl sulfide (DMS) or ethyl methyl sulfide, or a mixture of a sulfide-based odorant with thiols or thioethers.

[0067] The amount of sulfur-based odor component to be filled into the refrigerant circuit 10 is preferably 50 ppm by weight to 2000 ppm by weight relative to the amount of refrigerant filled. This allows people in the vicinity to recognize the abnormality due to the odor component if refrigerant or odor component leaks from the refrigerant circuit 10. The significance of setting the amount of odor component to 2000 ppm by weight or less will be explained in detail later.

[0068] <Refrigerating machine oil> Furthermore, the air conditioning system 1 has refrigerant oil sealed in the refrigerant circuit 10 along with the refrigerant and odor components. The refrigerant oil is mainly stored at the bottom of the compressor 21 within the refrigerant circuit 10 and circulated to the compression elements within the compressor 21 to maintain the lubrication of the sliding parts. In addition, a portion of the refrigerant oil circulates within the refrigerant circuit 10 together with the refrigerant and odor components. In other words, the refrigerant oil is mixed with the refrigerant and odor components and used as the working fluid for the refrigeration system. The ratio of refrigerant oil to the total amount of working fluid for the refrigeration system is preferably 10% by weight or more and 70% by weight or less, and more preferably 20% by weight or more and 60% by weight or less.

[0069] Examples of refrigeration oils include oxygen-containing synthetic oils and hydrocarbon-based refrigeration oils. Among these, polyalkylene glycol (PAG) is preferred as a hydrocarbon-based refrigerant from the viewpoint of compatibility, and polyalkylene glycol is used in this embodiment. The refrigeration oil may use one type of polyalkylene glycol alone, or two or more types in combination.

[0070] Polyalkylene glycol, a refrigerant oil, possesses properties such as flame retardancy, a low pour point, a high viscosity index, and excellent shear stability. Furthermore, polyalkylene glycol dissolves refrigerant and refrigerant oil when the concentration of refrigerant oil in the mixture is 40% by weight or more. This allows the air conditioning system 1 to circulate the refrigerant and refrigerant oil in a dissolved state within the refrigerant circuit 10 during operation. Additionally, polyalkylene glycol has a volume resistivity of 1 × 10⁻¹⁶ at 40°C. 6It is preferable to use compounds with a molecular weight of Ω·m or greater. This results in the polyalkylene glycol having high electrical insulation properties.

[0071] Furthermore, the refrigeration oil (polyalkylene glycol) according to the embodiment includes an extreme pressure agent, an antioxidant, and an acid scavenger as additives.

[0072] <Extreme pressure agent> Extreme pressure additives are additives used to prevent wear and seizure in sliding parts of compressors 21 and the like. Refrigerant oil prevents contact between sliding members by forming an oil film between the surfaces of sliding members that slide relative to each other in the compressor 21. However, when the pressure applied to the sliding members is high, they are more likely to come into contact with each other. Extreme pressure additives suppress wear and seizure by reacting with the surface of the sliding members in the compressor 21 to form a film. Examples of extreme pressure additives include phosphate esters, phosphite esters, thiophosphates, sulfide esters, sulfides, and thiobisphenol. Examples of extreme pressure additives include tricresyl phosphate (TCP), triphenyl phosphate (TPP), triphenyl phosphorothioate (TPPT), amines, C11-14 side-chain alkyls, monohexyl, and dihexyl phosphates. For example, TCP adsorbs to the surface of the sliding member and decomposes to form a phosphate film.

[0073] <Antioxidant> Antioxidants are additives used to prevent oxidation of refrigeration oil. Examples of antioxidants include zinc dithiophosphate, organosulfur compounds, phenolic compounds such as 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, and 2,2'-methylenebis(4-methyl-6-tert-butylphenol), amine compounds such as phenyl-α-naphthylamine and N,N'-diphenyl-p-phenylenediamine, and N,N'-disalisilidene-1,2-diaminopropane.

[0074] <Acid scavenger> Acid scavengers are additives used to capture acids generated within the refrigerant circuit 10. Acids generated in the refrigerant circuit 10 can cause deterioration of the refrigerant oil and corrosion of metal parts of the refrigerant circuit 10. These acids can be generated, for example, by the decomposition of odor components such as sulfides and thiophenes. Examples of acid scavengers include epoxy compounds, carbodiimide compounds, and terpene compounds. Specific examples of acid scavengers include 2-ethylhexylglycidyl ether, phenylglycidyl ether, epoxidized cyclohexylcarbinol, di(alkylphenyl)carbodiimide, and β-pinene.

[0075] The amount of acid scavenger added to the refrigerant oil should be designed according to the amount of refrigerant oil filled in the refrigerant circuit 10, the amount of odor components, etc. Specifically, the acid scavenger is preferably contained in an amount of 0.1% to 2.0% by weight relative to the refrigerant oil, and more preferably in an amount of 0.3% to 1.0% by weight relative to the refrigerant oil.

[0076] <Air volume in the refrigerant circuit> Furthermore, in the refrigerant circuit 10, the amount of air mixed into the refrigerant circuit 10 is controlled to be 500 ppm by weight or less relative to the refrigerant oil. The amount of air is reduced, for example, by the operator performing a vacuum evacuation of the filling tube when filling the refrigerant. This prevents the amount of acid scavenger from decreasing as the acid scavenger captures the air mixed into the refrigerant circuit 10.

[0077] <Moisture content in the refrigerant circuit> Furthermore, in the refrigerant circuit 10, the amount of water mixed into the refrigerant oil is controlled to be 200 ppm by weight or less. The amount of water is reduced, for example, by the operator performing a vacuum of the filling tube when filling the refrigerant. This suppresses the reaction between water mixed into the refrigerant circuit 10 and odor components, which can lead to the generation of acids from the odor components.

[0078] <Evaluation test of odor components and acid scavenging agent amounts> The air conditioning system 1 according to this embodiment is basically configured as described above. Next, an outline of an evaluation test, including confirmation of the corrosion status of metal parts, will be explained regarding the relationship between the amount of odor components filled and the amount of acid scavenger. Iron (carbon steel), copper, and aluminum were placed in a pressure-resistant and heat-resistant test container as metal parts used inside the refrigeration system. Sulfur-based odor components, R290 as a refrigerant, polyalkylene glycol mixed with extreme pressure agent, antioxidant, and acid scavenger as refrigeration oil, water, and air were mixed in, and the container was left to stand at 175°C for 30 days. After standing, the remaining amounts of extreme pressure agent, antioxidant, and acid scavenger in the refrigeration oil were measured, and the corrosion status of the metal parts was confirmed.

[0079] The results of the above evaluation tests will be explained with reference to Figures 2 and 3. Figure 2 is a graph showing the relationship between the amount of odor component filled into the refrigerant circuit 10 and the remaining acid scavenger in the refrigerant circuit 10.

[0080] The acid scavenger retention rate is the percentage of acid scavenger remaining in the refrigerant circuit 10 after a certain period of time (30 days) has elapsed since the refrigerant circuit 10 was filled with odor components and acid scavenger. The percentage of acid scavenger is the ratio of the amount of acid scavenger filled after a certain period of time to the standard amount of acid scavenger filled at the time of filling (100%).

[0081] Figure 2 shows the results of measuring the residual rate of the acid scavenger for each type of odor component, after changing the type of odor component filled into the refrigerant circuit 10. In the graph, the odor component shown as a solid line and diamond is tetrahydrothiophene (THT). In the graph, the odor component shown as a dotted line and triangle is dimethyl sulfide. In the graph, the odor component shown as a dashed line and square is ethyl methyl sulfide. In the graph, the odor component shown as a dotted line and circle is 2-ethyl 2-propanethol. Even when each odor component was changed, the amount of refrigerant oil and the amount of acid scavenger filled remained the same.

[0082] As shown in Figure 2, the remaining acid scavenger decreases as the concentration of odor components increases. In other words, it can be considered that the amount of acid scavenger decreases as the odor components generate acid within the refrigerant circuit 10, and this acid is captured by the acid scavenger. Even when the concentration of odor components is 0, the remaining acid scavenger is slightly over 80% because the acid scavenger captures air mixed into the refrigerant circuit 10, etc.

[0083] As shown in Figure 2, when the odor components are tetrahydrothiophene, dimethyl sulfide, and ethyl methyl sulfide, the residual rate of the acid scavenger gradually decreases as the concentration of the odor components increases. These odor components cause a linear decrease in the residual rate of the acid scavenger because the amount of acid generated increases in proportion to the concentration.

[0084] On the other hand, when the odor component is 2-ethyl 2-propanethol, the concentration of the odor component decreases rapidly up to 2000 ppm by weight, and thereafter, as the concentration of the odor component increases, the residual rate of the acid scavenger decreases gradually. In other words, 2-ethyl 2-propanethol generates acid at a certain level when filled into the refrigerant circuit 10, and it can be seen that the acid scavenger is used to contain this acid.

[0085] Preferably, the residual acid scavenger in the refrigerant circuit 10 is 70% or more. This allows the acid scavenger to effectively capture acids that may be generated during the operation of the air conditioning system 1, even if the amount of acid scavenger decreases after the refrigerant circuit 10 is filled. For example, even if partial separation of the refrigerant and refrigerant oil occurs due to the high temperature of the compressor 21, and acid is generated by the decomposition of the refrigerant, this acid can be effectively captured.

[0086] On the other hand, if the amount of scavenging agent decreases to less than 70% due to the filling of odor components, the likelihood of not being able to capture the acid generated in the refrigerant circuit 10 increases. Therefore, a threshold Th of 70% is set for the remaining acid scavenging agent. In this case, it was found that 2-ethyl 2-propanechiol falls below 70% even at 2000 ppm by weight, and from the perspective of reducing the acid scavenging agent, it can be said that it is not suitable as an odor component to fill the refrigerant circuit 10.

[0087] Tetrahydrothiophene, dimethyl sulfide, and ethyl methyl sulfide show an acid scavenging rate of 70% or more at 200 ppm by weight. However, the acid scavenging rate for each of these odor components gradually decreases as the concentration of the odor component increases, falling below 70% in the range of 6,000 ppm by weight to 10,000 ppm by weight. Furthermore, at 20,000 ppm by weight for all types of odor components, the acid scavenging rate is significantly different from 70% (around 60%).

[0088] Therefore, the upper limit concentration of odor components to be filled into the refrigerant circuit 10 is preferably tetrahydrothiophene, dimethyl sulfide, and ethyl methyl sulfide, but it is desirable that the concentration be 5000 ppm by weight or less. More preferably, considering the margin of residual acid scavenging agent remaining in the refrigerant circuit 10, it is preferable to set it to 2000 ppm by weight or less. Furthermore, the lower limit of odor components to be filled into the refrigerant circuit 10 is preferably a concentration that allows the odor components tetrahydrothiophene, dimethyl sulfide, and ethyl methyl sulfide to exert their functions. In this case, the lower limit concentration of odor components is 50 ppm by weight. Therefore, it can be said that the amount of odor components filled relative to the amount of refrigerant filled is preferably 50 ppm by weight to 2000 ppm by weight.

[0089] Furthermore, as shown in Figure 3, we confirmed whether metal corrosion occurred on the metal parts of the refrigerant circuit 10 for various odor components at 2000 ppm by weight. Examples of metal parts in the refrigerant circuit 10 include the metal parts of the expansion mechanism 23 (expansion valve). When tetrahydrothiophene, dimethyl sulfide, and ethyl methyl sulfide were applied at 2000 ppm by weight of odor components, no metal corrosion was observed on the metal parts of the expansion mechanism 23. On the other hand, when 2-ethyl 2-propanechol was applied at 2000 ppm by weight of odor components, metal corrosion was observed in the copper parts. This suggests that, in the case of 2-ethyl 2-propanechol, acid generated within the refrigerant circuit 10 and not completely captured by the acid scavenger reacted with the metal parts, causing metal corrosion. Therefore, from the perspective of metal corrosion, applying 2-ethyl 2-propanechol as an odor component is not appropriate, and it is preferable to apply tetrahydrothiophene, dimethyl sulfide, and ethyl methyl sulfide.

[0090] Furthermore, as mentioned above, the amount of acid scavenger to be filled should be in the range of 0.1% to 2.0% by weight relative to the refrigerant oil. If the amount of acid scavenger is less than 0.1% by weight, even if the total amount of refrigerant oil is large, the amount of acid scavenger will be small, and the function of the acid scavenger to capture acid in the refrigerant circuit 10 will be insufficient. Conversely, if the amount of acid scavenger exceeds 2.0% by weight, the viscosity of the refrigerant oil will be low, and the lubricating function of the refrigerant oil when lubricating the compressor 21 will be insufficient.

[0091] Specifically, the viscosity (kinematic viscosity) of the mixture containing refrigerant oil and acid scavenger in the refrigerant circuit 10 at 40°C should be in the range of 5 cSt to 300 cSt. This allows the refrigerant oil and acid scavenger to move within the refrigerant circuit 10 with appropriate viscosity. If the viscosity of the mixture of refrigerant oil and acid scavenger is less than 5 cSt, there is a high possibility that the lubrication of the compressor 21 by the refrigerant oil will not be ensured. Furthermore, if the viscosity of the mixture of refrigerant oil and acid scavenger exceeds 300 cSt, there is a high possibility that it will affect the circulation of the refrigerant within the refrigerant circuit 10, leading to problems such as the refrigerant not being able to move smoothly.

[0092] In particular, by setting the amount of acid scavenger to be filled in the range of 0.3% to 1.0% by weight relative to the refrigerant oil, it is possible to maintain a high level of function of the refrigerant oil while ensuring a sufficient amount of acid scavenger in the refrigerant circuit 10.

[0093] The concentration of refrigerant oil (polyalkylene glycol) relative to the refrigerant is 40% by weight, in which case the polyalkylene glycol dissolves in the refrigerant. The mixture of refrigerant and refrigerant oil can stably suppress the decomposition of the refrigerant within the refrigerant circuit 10 and suppress the generation of acid from the refrigerant itself.

[0094] Furthermore, the air conditioning system 1 controls the discharge gas temperature of the refrigerant discharged from the discharge connection terminal 21o of the compressor 21 to 120°C or lower. This avoids the problem of the refrigerant and refrigerant oil being decomposed due to high temperatures inside the refrigerant circuit 10, and also suppresses the decomposition of odor components contained in the refrigerant circuit 10.

[0095] It should be noted that the refrigeration system described herein is not limited to the above-described embodiment and can be modified in various ways. For example, the refrigeration system is not limited to the air conditioning system 1, but may be a hot water supply system, a cooling water circulation system, etc. An example of a hot water supply system is a heat pump type. An example of a cooling water circulation system is a chiller that circulates a refrigerant and adjusts its temperature for the device to be cooled.

[0096] <Regarding the nature and effects of this disclosure> The embodiments disclosed above have, for example, the following aspects and effects.

[0097] [Note 1] A refrigeration system comprising a compressor, a condenser, an expansion mechanism, an evaporator, and a refrigerant circuit for circulating refrigerant and refrigerant oil, The aforementioned expansion mechanism has an expansion valve including a metal component, The refrigerant contains hydrocarbons having 1 to 4 carbon atoms. The refrigeration oil is polyalkylene glycol and contains 0.1% to 2.0% by weight of an acid scavenger relative to the refrigeration oil. The amount of sulfur-based odor components relative to the amount of refrigerant is 50 ppm by weight to 2000 ppm by weight. Refrigeration equipment.

[0098] [Effects of Appendix 1] According to the above, the 50% to 2000% by weight of odor components packed into the refrigerant circuit can sufficiently increase the remaining percentage of the 0.1% to 2.0% by weight of acid scavenger added to the refrigerant oil. This makes it possible to effectively capture any acid generated by the decomposition of odor components in the refrigerant circuit using the acid scavenger.

[0099] [Note 2] The acid scavenger is present in an amount of 0.3% to 1.0% by weight relative to the refrigerant oil. The refrigeration equipment described in Appendix 1.

[0100] [Effects of Appendix 2] This allows the refrigeration system to fill the refrigerant circuit with an amount of acid scavenger sufficient to capture the acid in the refrigerant circuit while ensuring the lubrication of the refrigerant oil.

[0101] [Note 3] The amount of air mixed into the refrigerant circuit with respect to the refrigerant oil is 500 ppm by weight or less. The refrigeration equipment described in Appendix 1 or 2.

[0102] [Effects of Appendix 3] This allows the refrigeration system to capture acid in the air mixed into the refrigerant circuit using an acid scavenger, thereby reducing the amount of acid in the refrigerant circuit, and also suppressing the decrease in the amount of acid scavenger after refilling.

[0103] [Note 4] The amount of water mixed into the refrigerant circuit with respect to the refrigerant oil is 200 ppm by weight or less. A refrigeration device as described in any one of the following appendices 1 to 3.

[0104] [Effects of Appendix 4] This allows the refrigeration system to capture the acid generated from water mixed into the refrigerant circuit using an acid scavenger, thereby reducing the amount of acid in the refrigerant circuit, and also suppressing the decrease in the amount of acid scavenger after refilling.

[0105] [Note 5] The refrigerant oil is an oil in which the refrigerant and the refrigerant oil dissolve when the concentration of the refrigerant oil in the mixture of the refrigerant and the refrigerant oil is 40% by weight or more. A refrigeration device as described in any one of the appendices 1 to 4.

[0106] [Effects of Appendix 5] As a result, the refrigeration system can circulate the refrigerant oil effectively by allowing the refrigerant and refrigerant oil to dissolve in the refrigerant circuit.

[0107] [Note 6] The aforementioned refrigeration oil further contains an extreme pressure agent. A refrigeration device as described in any one of the appendices 1 to 5.

[0108] [Effects of Appendix 5] As a result, the refrigeration system can effectively avoid wear and seizure in the compressor of the refrigerant circuit.

[0109] [Note 7] The aforementioned refrigeration oil further contains an antioxidant. A refrigeration device as described in any one of the appendices 1 to 6.

[0110] [Effects of Appendix 7] This allows the refrigeration system to reduce the oxidation of the refrigerant oil itself.

[0111] [Note 8] The discharge gas temperature of the refrigerant discharged from the compressor is controlled to be 120°C or lower. A refrigeration device as described in any one of the appendices 1 to 7.

[0112] [Effects of Appendix 8] This allows the refrigeration system to keep the temperatures of the refrigerant, odor components, and refrigerant oil low, thereby suppressing the decomposition of odor components.

[0113] [Note 9] The aforementioned refrigerant is a highly flammable refrigerant. A refrigeration device as described in any one of the appendices 1 to 8.

[0114] [Effects of Appendix 9] As a result, the refrigeration system can fill the refrigerant circuit with a refrigerant with a low GWP value, enabling efficient heat exchange by the refrigerant in the condenser and evaporator. Furthermore, because the amount of odor components filled is between 50% and 2000% by weight, the odor components leak out along with the refrigerant, making it possible to consistently induce people to avoid the odor.

[0115] [Note 10] The odor component is selected from the group consisting of sulfides and thiophenes. A refrigeration device as described in any one of the appendices 1 to 9.

[0116] [Effects of Appendix 10] This helps to suppress the significant reduction of the acid scavenger caused by odor components filling the refrigerant circuit.

[0117] [Note 11] The odor component is tetrahydrothiophene. The refrigeration equipment described in Appendix 10.

[0118] [Effects of Appendix 11] This allows odor components to suppress the reduction of the acid scavenging agent while also enabling people to recognize abnormalities in the refrigerant circuit when a leak occurs.

[0119] [Note 12] The odor component is dimethyl sulfide. The refrigeration equipment described in Appendix 10.

[0120] [Effects of Appendix 12] Even in this case, the odor components can suppress the decrease of the acid scavenging agent while allowing people to recognize an abnormality in the refrigerant circuit leak.

[0121] [Note 13] The odor component is ethyl methyl sulfide. The refrigeration equipment described in Appendix 10.

[0122] [Effects of Appendix 13] Even in this case, the odor components can suppress the decrease of the acid scavenging agent while allowing people to recognize an abnormality in the refrigerant circuit leak.

[0123] [Note 14] The viscosity of the mixture containing the refrigerant oil and the acid scavenger at 40°C is 5 cSt to 300 cSt. A refrigeration device as described in any one of the appendices 1 to 13.

[0124] [Effects of Appendix 14] Thus, by having a viscosity of 5 cSt to 300 cSt between the refrigerant oil and the acid scavenger, the refrigerant oil with the added acid scavenger can be smoothly circulated in the refrigerant circuit while ensuring the lubrication of the compressor.

[0125] [Note 15] The aforementioned refrigerant oil has a volume resistivity of 1 × 10 at 40°C. 6 It is greater than or equal to Ω·m. A refrigeration device as described in any one of the appendices 1 to 14.

[0126] [Effects of Appendix 15] Thus, the volume resistivity of the refrigerant oil is 1 × 10⁻⁶ 6 By having a resistance of Ω·m or higher, electrical insulation is ensured, and current leakage from electrical components such as motor windings inside the compressor to the outside of the refrigerant circuit through the refrigerant oil can be suppressed.

[0127] [Note 16] The aforementioned refrigeration device is an air conditioning device, a hot water supply device, or a cooling water circulation device. A refrigeration device as described in any one of the appendices 1 to 15.

[0128] [Effects of Appendix 16] As a result, air conditioning systems, hot water supply systems, or cooling water circulation systems can ensure a sufficient amount of acid scavenging agent in the refrigerant circuit during operation, thereby reducing the occurrence of metal corrosion and other issues.

[0129] The refrigeration apparatus 1 according to the embodiments disclosed herein is illustrative in all respects and not restrictive. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be otherwise configured and combined in a non-consistent manner. [Explanation of Symbols]

[0130] 1. Air conditioning system (refrigeration system) 10 Refrigerant Circuit 22 Outdoor heat exchanger (condenser) 23 Expansion Mechanism 31. Indoor heat exchanger (evaporator)

Claims

1. A refrigeration system (1) comprising a compressor (21), a condenser (22), an expansion mechanism (23), an evaporator (31), and a refrigerant circuit (10) for circulating refrigerant and refrigerant oil, The expansion mechanism (23) has an expansion valve including a metal part, The refrigerant comprises hydrocarbons having 1 to 4 carbon atoms. The refrigeration oil is polyalkylene glycol and contains 0.1% to 2.0% by weight of an acid scavenger relative to the refrigeration oil. The amount of sulfur-based odor components relative to the amount of refrigerant is 50 ppm by weight to 2000 ppm by weight. Refrigeration device (1).

2. The acid scavenger is present in an amount of 0.3% to 1.0% by weight relative to the refrigeration oil. The refrigeration apparatus (1) according to claim 1.

3. The amount of air mixed into the refrigerant circuit (10) with respect to the refrigerant oil is 500 ppm by weight or less. The refrigeration apparatus (1) according to claim 1 or 2.

4. The amount of water mixed into the refrigerant circuit (10) with respect to the refrigerant oil is 200 ppm by weight or less. The refrigeration apparatus (1) according to claim 1 or 2.

5. The refrigerant oil is an oil in which the refrigerant and the refrigerant oil dissolve when the concentration of the refrigerant oil in the mixture of the refrigerant and the refrigerant oil is 40% by weight or more. The refrigeration apparatus (1) according to claim 1 or 2.

6. The aforementioned refrigeration oil further contains an extreme pressure agent. The refrigeration apparatus (1) according to claim 1 or 2.

7. The aforementioned refrigeration oil further contains an antioxidant. The refrigeration apparatus (1) according to claim 1 or 2.

8. The discharge gas temperature of the refrigerant discharged from the compressor is controlled to be 120°C or lower. The refrigeration apparatus (1) according to claim 1 or 2.

9. The aforementioned refrigerant is a highly flammable refrigerant. The refrigeration apparatus (1) according to claim 1 or 2.

10. The odor component is selected from the group consisting of sulfides and thiophenes. The refrigeration apparatus (1) according to claim 1 or 2.

11. The odor component is tetrahydrothiophene. The refrigeration apparatus (1) according to claim 10.

12. The odor component is dimethyl sulfide. The refrigeration apparatus (1) according to claim 10.

13. The odor component is ethyl methyl sulfide. The refrigeration apparatus (1) according to claim 10.

14. The viscosity of the mixture containing the refrigerant oil and the acid scavenger at 40°C is 5 cSt to 300 cSt. The refrigeration apparatus (1) according to claim 1 or 2.

15. The aforementioned refrigerant oil has a volume resistivity of 1 × 10 at 40°C. ６ It is greater than or equal to Ω·m. The refrigeration apparatus (1) according to claim 1 or 2.

16. The refrigeration device (1) is an air conditioning device, a hot water supply device, or a cooling water circulation device. The refrigeration apparatus (1) according to claim 1 or 2.

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