Air conditioners

Abstract

To solve the problem in a conventional air conditioner using non-azeotropic refrigerant mixture that there are deterioration of performance due to temperature slip or pressure loss, increase in size of the device, and insufficient safety at the time of leakage in a case of using combustible refrigerant.SOLUTION: An air conditioner comprises a gas-liquid separator 110 provided between a second outdoor heat exchanger 104G and a first outdoor heat exchanger 104L in the middle of an outdoor heat exchanger 104, and an accumulator 113 provided with a liquid gas heat exchanger 114 inside; and stores liquid refrigerant in an outdoor machine 101. Even when combustible refrigerant is used as a high boiling point component of non-azeotropic mixed refrigerant, the air conditioner can reduce a ratio of the combustible refrigerant flowing into an indoor machine 107 to improve safety at the time of leakage and the performance of the device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technique for improving the safety and operational efficiency of an air conditioner that uses a non-azeotropic refrigerant mixture in an air conditioner that performs air conditioning using a refrigeration and heat pump cycle. [Background technology]

[0002] In recent years, in order to prevent global warming, there has been an increasing trend to place importance on the operating efficiency of air conditioners, as well as to regulate the use of refrigerants with high global warming potential.

[0003] Refrigerants with low global warming potential include naturally occurring carbon dioxide and hydrocarbons such as propane and butane, while artificially synthesized fluorocarbons such as hydrofluoroolefins (HFOs), which have double bonds in their molecular structure and decompose in a short time in the atmosphere, have attracted attention.

[0004] However, carbon dioxide has a high operating pressure, making it difficult to operate efficiently when used in air conditioners, and hydrocarbons have safety issues due to their high flammability. HFOs such as 2,3,3,3-tetrafluoro-1-propene (R1234yf) and 1,3,3,3-tetrafluoro-1-propene (R1234ze) are slightly flammable, have high boiling points and large pressure losses, and can therefore be problematic in terms of operating efficiency.

[0005] Another proposal has been made for 1,1,2-trifluoroethylene (HFO1123). This refrigerant has a more favorable boiling point than R1234yf and other refrigerants, but is slightly flammable and prone to self-decomposition. If used alone, there is a risk of an explosion due to self-decomposition triggered by discharge in the compressor motor under certain high temperature and pressure conditions.

[0006] It has also been pointed out that 1,1-difluoroethylene (HFO1132a) and trans-1,2-difluoroethylene (HFO1132e) may be effective refrigerants in preventing global warming, but they are thought to have similar issues to those of HFO1123.

[0007] Due to these challenges, it is difficult to select a refrigerant that exhibits excellent overall characteristics on its own, and it has been found possible to use a selection of several refrigerants in combination.

[0008] When different types of refrigerants are mixed, the boiling points of the individual refrigerants are often not the same, and the mixed refrigerant exhibits a characteristic known as temperature slip, in which the saturation temperature at a constant pressure will not be constant and the saturation temperature on the liquid phase side will be lower than the saturation temperature on the gas phase side.

[0009] Furthermore, the components of the refrigerant in a two-phase gas-liquid state differ between the gas phase and the liquid phase, with the gas phase containing more low-boiling point components.

[0010] In general, the difference in saturation temperature and the change in composition between the gas and liquid phases due to temperature slip vary depending on the type and mixture ratio of the refrigerant being mixed, and temperature slip is one of the factors that reduces the performance of an air conditioner.

[0011] Furthermore, refrigerants with low global warming potential often have characteristics such as being flammable or having an unstable structure, and technological development is therefore required to improve their safety and reliability.

[0012] One of these technologies is a technology that provides a heating mechanism for heating the refrigerant sent from the evaporator to the compressor, thereby improving reliability and performance.

[0013] Patent Document 1 discloses a refrigeration device as an example of a technique for heating the refrigerant sent from an evaporator to a compressor by a heating mechanism.

[0014] As shown in FIG. 4, an air conditioner 1, which is an example of the refrigeration device of Patent Document 1, has a refrigerant circuit 210 that is composed of a hermetic compressor 2 driven by a drive motor 2a, a heat source side heat exchanger 4, an expansion mechanism 5, a user side heat exchanger 6, an internal heat exchanger 11 which is a heating mechanism 8, a bridge circuit 16 consisting of inlet check valves 16a, 16b and outlet check valves 16c, 16d, a receiver 18, and an accumulator 17.

[0015] By the bridge circuit 16, in either cooling operation or heating operation, the refrigerant flowing through the internal heat exchanger 11 flows in through the inlet pipe 19a and flows out through the outlet pipe 19b.

[0016] Examples of refrigerants to be used include HFO refrigerants with three carbon atoms or mixed refrigerants. Specific examples of HFO refrigerants include R1234yf or R1234ze, and mixed refrigerants include difluoromethane (R32) and pentafluoroethane (R125).

[0017] The global warming potential (over 100 years) of the above refrigerants is 675 for R32, and 4 for both R1234yf and R1234ze, making them important refrigerants in terms of preventing global warming. Here, R125 has a large global warming potential of 3500, which does not lead to a reduction in the global warming potential, and its purpose is to make it non-flammable.

[0018] During cooling operation, the high-temperature, high-pressure refrigerant discharged from the compressor 2 condenses and releases heat in the heat source side heat exchanger 4, then passes through the internal heat exchanger 11, is reduced in pressure in the expansion mechanism 5, and evaporates and absorbs heat in the user side heat exchanger 6 to perform cooling, before returning to the compressor 2 via the internal heat exchanger 11.

[0019] At this time, in the internal heat exchanger 11, the refrigerant that has absorbed heat in the user-side heat exchanger 6 is heated by the refrigerant that is still at a relatively high temperature after dissipating heat in the heat source-side heat exchanger 4, thereby preventing the liquid refrigerant from being sucked into the compressor 2.

[0020] Furthermore, in the air conditioner 1, liquid refrigerant does not accumulate in the accumulator 17, and the receiver 18 receives the refrigerant after condensation, so that changes in the composition of the mixed refrigerant are kept to a minimum, and the desired capacity can be obtained.

[0021] Internal heat exchangers, commonly known as liquid-gas heat exchangers, are installed to maintain appropriate levels of subcooling before the expansion mechanism and superheating before the compressor suction, and to prevent the generation of flash gas before expansion and liquid return at the compressor suction, and have long been known for providing benefits such as improved reliability and performance.

[0022] Another example of the technology is disclosed in Patent Document 2, which includes a composition adjustment means for storing liquid refrigerant and increasing the composition of low-boiling point components in the non-azeotropic refrigerant mixture circulating in the refrigerant circuit.

[0023] Patent Document 2 shows an example of using an accumulator as a composition adjustment means, an example of using a composition adjustment unit that is equipped with a packed tower that evaporates a lot of low boiling point components and separates them from liquid refrigerant containing a lot of high boiling point components, and a liquid storage vessel that stores liquid refrigerant containing a lot of high boiling point components, and can be connected / disconnected from a main refrigerant circuit, and shows a method of adjusting the amount of low boiling point components charged to the main refrigerant circuit.

[0024] The refrigerants described in Patent Documents 1 and 2 are classified as non-flammable or slightly flammable, and are intended to improve the reliability and performance of the equipment. However, when using a highly flammable refrigerant such as a hydrocarbon, it is possible to suppress flammability by mixing it with a non-flammable or slightly flammable refrigerant, but it is difficult to make it completely non-flammable when considering environmental aspects.

[0025] To improve safety, there are technologies that detect refrigerant leakage and control the blowing means to promote diffusion of the refrigerant and prevent the creation of flammable areas, as well as technologies such as that described in Patent Document 3, which cut off the refrigerant circuit between the outdoor unit and the indoor unit.

[0026] Patent Document 3 discloses an inexpensive device that shuts off a refrigerant circuit using an expansion valve and a shutoff valve, rather than using multiple shutoff valves. When a control device detects a refrigerant leak, the expansion valve and the shutoff valve shut off the refrigerant circuit. [Prior art documents] [Patent documents]

[0027] [Patent Document 1] JP 2009-222348 A [Patent Document 2] Patent No. 3749092 [Patent Document 3] JP 2000-97527 A Summary of the Invention [Problem to be solved by the invention]

[0028] In air-conditioning systems using the conventional technology of Patent Document 1, the internal heat exchanger is used to improve reliability and also serves to prevent performance degradation due to temperature slippage and pressure loss in the connecting piping during cooling operation, but it is difficult to obtain a sufficient improvement in performance with this alone.

[0029] The technology of Patent Document 2 aims to improve performance by changing the circulating composition using a liquid storage container of a fixed capacity; however, the liquid storage container makes it unavoidable to increase the size of the device, and there is a problem that the amount of refrigerant charged increases because some of the charged refrigerant remains stagnant without circulating.

[0030] The technology of Patent Document 3 has a problem in that, when refrigerant leaks from an indoor unit, the leakage occurs due to the composition of the circulating refrigerant, and therefore the flammability of the leaking refrigerant cannot be reduced.

[0031] Therefore, the present invention solves these problems, suppresses performance degradation due to temperature slippage, pressure loss, etc., and improves the performance of the refrigerant flowing through the indoor unit even with a small amount of refrigerant charged by adjusting the composition of the refrigerant flowing through the user-side heat exchanger, and reduces the proportion of flammable refrigerant in the refrigerant flowing through the indoor unit, thereby reducing the flammability of leaking refrigerant and suppressing the risk of fire. [Means for solving the problem]

[0032] In order to solve the above-mentioned problems in the related art, the first air conditioner of the present invention is an air conditioner that constitutes a refrigeration or heat pump cycle, and is comprised of an outdoor unit having a compressor that compresses and sends out a working refrigerant, an outdoor heat exchanger that exchanges heat between the working refrigerant and outdoor air sent by an outdoor blower, and an indoor unit having an indoor heat exchanger that exchanges heat between the working refrigerant and indoor air sent by an indoor blower, and uses a mixture of at least two or more types of refrigerants with different boiling points as the working refrigerant, uses a refrigerant that is highly flammable or combustible as the high-boiling point refrigerant for the working refrigerant, and is equipped in the outdoor unit with refrigerant storage means for storing liquid of the working refrigerant.

[0033] This allows a highly flammable or combustible high-boiling-point refrigerant to be stored in the refrigerant storage means, and allows the refrigerant ratio of high-boiling-point components to be reduced when circulating through the indoor unit.

[0034] In addition, in order to solve the above-mentioned problems of the conventional art, the second air conditioner of the present invention is an air conditioner which constitutes a refrigeration or heat pump cycle, and which comprises an outdoor unit having a compressor which compresses and sends out a working refrigerant, an outdoor heat exchanger which exchanges heat between the working refrigerant and outdoor air sent by an outdoor blower, and an indoor unit having an indoor heat exchanger which exchanges heat between the working refrigerant and indoor air sent by an indoor blower, in which a mixture of at least two or more types of refrigerants having different boiling points is used as the working refrigerant, a first refrigerant storage means for storing the liquid working refrigerant is provided midway through the outdoor heat exchanger, the liquid refrigerant stored in the first refrigerant storage means is discharged, evaporated via a first refrigerant heat exchange means which exchanges heat with the circulating refrigerant on the condensed liquid side, and led to the suction port of the compressor.

[0035] As a result, by storing a refrigerant with a high boiling point that causes a decrease in performance in the first refrigerant storage means, during cooling operation, a higher ratio of refrigerant with a low boiling point component, which has superior performance, can be circulated in the refrigerant circuit that runs from the latter half of the outdoor heat exchanger through the indoor heat exchanger to the compressor suction port.Furthermore, the amount of working refrigerant flowing can be reduced, thereby reducing the pressure loss from the indoor heat exchanger to the compressor suction port.

[0036] Furthermore, in order to solve the above-mentioned problems of the conventional art, a third air conditioner of the present invention is an air conditioner which constitutes a refrigeration or heat pump cycle and which comprises an outdoor unit having a compressor which compresses and sends out a working refrigerant, an outdoor heat exchanger which exchanges heat between the working refrigerant and outdoor air sent by an outdoor blower, and an indoor unit having an indoor heat exchanger which exchanges heat between the working refrigerant and indoor air sent by an indoor blower, and which uses a mixture of at least two or more types of refrigerants having different boiling points as the working refrigerant, and which is provided with a second refrigerant storage means which stores the working refrigerant as a liquid in front of the suction port of the compressor, and a second inter-refrigerant heat exchange means which exchanges heat between the liquid refrigerant stored inside the second refrigerant storage means and the circulating refrigerant on the condensed liquid side.

[0037] As a result, by storing a refrigerant with a high boiling point that causes performance degradation in the second refrigerant storage means, a high ratio of refrigerant with low boiling point components that have superior performance can be circulated in the refrigerant circuit that runs from the second refrigerant storage means through the compressor, through the outdoor heat exchange and the indoor heat exchange, and back to the second refrigerant storage means.By exchanging heat between the refrigerant that has left the outdoor heat exchanger during cooling operation, and the refrigerant that has left the indoor heat exchanger during heating operation, with the refrigerant just before the compressor suction port, it is possible to suppress performance degradation due to temperature slippage, pressure loss, etc. Effect of the Invention

[0038] The first air conditioner of the present invention uses a mixture of at least two or more refrigerants with different boiling points, and when a highly flammable or combustible refrigerant is used as the high-boiling point refrigerant for the working refrigerant, the highly flammable or combustible high-boiling point refrigerant is stored in the refrigerant storage means, and the proportion of high boiling point components contained in the refrigerant flowing through the indoor unit is reduced.Therefore, even if a refrigerant leak occurs in the indoor unit, the risk of fire is reduced, and an air conditioner with excellent safety can be provided.

[0039] In addition, the second air conditioner of the present invention uses a mixture of at least two or more types of refrigerants having different boiling points, and stores the high boiling point components using a first refrigerant storage means and a first refrigerant heat exchange means, thereby increasing the ratio of the low boiling point components flowing through the main refrigerant circulation circuit, thereby improving the performance of the working fluid and reducing pressure loss, thereby providing an air conditioner with excellent operating efficiency.

[0040] In addition, the third air conditioner of the present invention uses a mixture of at least two or more types of refrigerants having different boiling points, and stores the high boiling point components using a second refrigerant storage means and a second refrigerant heat exchange means, thereby increasing the ratio of the low boiling point components flowing through the refrigerant circulation circuit, thereby improving the performance of the working fluid and suppressing performance degradation due to temperature slippage and pressure loss, thereby providing an air conditioner with excellent operating efficiency. [Brief description of the drawings]

[0041] [Figure 1]A configuration diagram of an air conditioner according to a first embodiment of the present invention. [Diagram 2] 1 is a schematic diagram of a gas-liquid separator according to a first embodiment of the present invention; [Diagram 3] 1 is a schematic diagram of an accumulator and a liquid-gas heat exchanger according to a first embodiment of the present invention; [Figure 4] Diagram of the configuration of an air conditioner equipped with a conventional liquid-gas heat exchanger (internal heat exchanger) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] The first invention is an air conditioner that constitutes a refrigeration or heat pump cycle and is comprised of an outdoor unit having a compressor that compresses and sends out a working refrigerant, an outdoor heat exchanger that exchanges heat between the working refrigerant and outdoor air sent by an outdoor blower, and an indoor unit having an indoor heat exchanger that exchanges heat between the working refrigerant and indoor air sent by an indoor blower, in which a mixture of at least two or more types of refrigerants having different boiling points is used as the working refrigerant, a refrigerant that is highly flammable or combustible is used as the high-boiling point refrigerant for the working refrigerant, and the outdoor unit is provided with a refrigerant storage means for storing liquid of the working refrigerant.

[0043] This allows a highly flammable or combustible high-boiling-point refrigerant to be stored in the refrigerant storage means, and allows the refrigerant ratio of high-boiling-point components to be reduced when circulating through the indoor unit.

[0044] Therefore, even if a refrigerant leak occurs in the indoor unit, the risk of fire is reduced, making it possible to provide an air conditioner that is extremely safe.

[0045] The second invention is an air conditioner that configures a refrigeration or heat pump cycle and is comprised of a compressor that compresses and sends out a working refrigerant, an outdoor unit having an outdoor heat exchanger that exchanges heat between the working refrigerant and outdoor air sent by an outdoor blower, and an indoor unit having an indoor heat exchanger that exchanges heat between the working refrigerant and indoor air sent by an indoor blower, in which a mixture of at least two or more types of refrigerants having different boiling points is used as the working refrigerant, a first refrigerant storage means for storing the working refrigerant in liquid form is provided midway through the outdoor heat exchanger, and the liquid refrigerant stored in the first refrigerant storage means is discharged and guided to the suction port of the compressor via a first refrigerant heat exchange means that cools the circulating refrigerant on the condensed liquid side.

[0046] As a result, by storing a refrigerant with a high boiling point that causes a decrease in performance in the first refrigerant storage means, a higher ratio of refrigerant with a low boiling point component, which has superior performance, can be circulated in the refrigerant circuit that runs from the latter half of the outdoor heat exchanger through the indoor heat exchanger to the compressor suction port during cooling operation.The amount of working refrigerant flowing can also be reduced, thereby reducing the pressure loss from the indoor heat exchanger to the compressor suction port.

[0047] Therefore, it is possible to provide an air conditioner with excellent operating efficiency.

[0048] The third invention is an air conditioner which constitutes a refrigeration or heat pump cycle and which comprises an outdoor unit having a compressor which compresses and sends out a working refrigerant, an outdoor heat exchanger which exchanges heat between the working refrigerant and outdoor air sent by an outdoor blower, and an indoor unit having an indoor heat exchanger which exchanges heat between the working refrigerant and indoor air sent by an indoor blower, in which the working refrigerant is a mixture of at least two types of refrigerants having different boiling points, and which is provided with a second refrigerant storage means which stores the working refrigerant as a liquid in front of the suction port of the compressor, and a second refrigerant heat exchange means which exchanges heat between the refrigerant stored inside the second refrigerant storage means and a circulating refrigerant on the condensed liquid side.

[0049] As a result, by storing a refrigerant with a high boiling point that causes performance degradation in the second refrigerant storage means, a high ratio of refrigerant with low boiling point components that have superior performance can be circulated in the refrigerant circuit that runs from the second refrigerant storage means through the compressor, outdoor heat exchange and indoor heat exchange, and returns to the second refrigerant storage means.By exchanging heat between the refrigerant that has left the outdoor heat exchanger during cooling operation, and the refrigerant that has left the indoor heat exchanger during heating operation, with the refrigerant just before the compressor's intake port, it is possible to suppress performance degradation due to temperature slippage, pressure loss, etc.

[0050] Therefore, it is possible to provide an air conditioner with excellent operating efficiency.

[0051] A fourth aspect of the present invention relates to any one of the first to third aspects of the present invention, and further relates to a compressor in which a hydrocarbon is used as the high boiling point refrigerant of the working refrigerant.

[0052] Hydrocarbons are refrigerants that exist in nature and have a low global warming potential.

[0053] Therefore, it is possible to provide an air conditioner that is excellent in suppressing global warming.

[0054] A fifth aspect of the present invention relates to the fourth aspect of the present invention, in which propane or isobutane is used as the hydrocarbon.

[0055] Propane and isobutane are suitable for air conditioning in terms of their evaporation temperature and thermal properties, and are used in a variety of fields for purposes other than refrigerants as well. They are produced in large quantities and can be easily procured.

[0056] Therefore, it is possible to provide an air conditioner that is inexpensive and has excellent operating efficiency.

[0057] A sixth invention is any one of the first to fifth inventions, in which at least one of 1,1,2-trifluoroethylene (HFO1123), 1,1-difluoroethylene (HFO1132a), and trans-1,2-difluoroethylene (HFO1132e) is used as the low-boiling point refrigerant of the working refrigerant.

[0058] HFO1123, HFO1132a, and HFO1132e have low global warming potentials and are suitable for air conditioning due to their evaporation temperatures and thermal properties.

[0059] Therefore, it is possible to provide an air conditioner that is excellent in suppressing global warming.

[0060] A seventh invention is related to the second invention, wherein the first refrigerant storage means is a gas-liquid separator having a first connection port at an upper part thereof connected to a first outdoor heat exchanger, a liquid refrigerant discharge port at a lower part thereof connected to the first refrigerant-to-refrigerant heat exchange means, and a second connection port at a position between the first connection port and the liquid refrigerant discharge port thereof connected to a second outdoor heat exchanger.

[0061] This allows liquid refrigerant to be efficiently stored between the liquid refrigerant discharge port and the second connection port, reducing the proportion of high-boiling point refrigerant flowing from the latter half of the outdoor heat exchanger to the indoor heat exchanger during cooling operation, and reducing the amount of working refrigerant flowing through the indoor unit outlet, thereby reducing pressure loss.

[0062] Therefore, it is possible to provide an air conditioner with excellent operating efficiency.

[0063] An eighth aspect of the present invention relates to the third aspect of the present invention, wherein the second refrigerant storage means is an accumulator, and the second refrigerant heat exchange means is disposed at a predetermined height within the second refrigerant storage means.

[0064] As a result, liquid refrigerant can be reliably stored in the space below the second refrigerant heat exchange means of the second refrigerant storage means, and a high ratio of low boiling point components with excellent performance can be circulated in the refrigerant circuit that runs from the second refrigerant storage means through the compressor, outdoor heat exchange and indoor heat exchange, and returns to the second refrigerant storage means.By exchanging heat between the refrigerant that has left the outdoor heat exchanger during cooling operation, and the refrigerant that has left the indoor heat exchanger during heating operation, with the refrigerant just before the compressor suction port, it is possible to suppress performance degradation due to temperature slippage, pressure loss, etc.

[0065] Therefore, it is possible to provide an air conditioner with excellent operating efficiency.

[0066] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 shows a configuration diagram of an air conditioner according to a first embodiment of the present invention.

[0067] As shown in FIG. 1, the air conditioner in the first embodiment is a device that performs cooling or heating by circulating a refrigerant through an outdoor unit 101 and an indoor unit 107 connected in a circular fashion by piping.

[0068] The outdoor unit 101 includes a compressor 102 that compresses the refrigerant, a four-way valve 103 that switches the flow of the refrigerant discharged from the compressor 102, an outdoor heat exchanger 104 that exchanges heat between the refrigerant and outside air sent by an outdoor fan 105, an expansion valve 106C (for cooling) and an expansion valve 106H (for heating) that reduce the pressure of the high-pressure refrigerant and expand it, and an accumulator 113 to prevent liquid refrigerant from being sucked into the suction port of the compressor 102. The outdoor unit 101 also includes a liquid-side connection valve 115 and a gas-side connection valve 116, and is connected to the indoor unit 107 via these two valves. The liquid-side connection valve 115 and the gas-side connection valve 116 can be opened and closed to seal the refrigerant in the outdoor unit 101 and to shut off the refrigerant circuit in the event of a refrigerant leak, thereby minimizing the amount of refrigerant leaking to the indoor unit 107.

[0069] In FIG. 1, the expansion means uses two expansion valves, expansion valve 106H and expansion valve 106C. However, if a bridge circuit is formed using a check valve, it is also possible to use only one expansion valve.

[0070] The indoor unit 107 is equipped with an indoor heat exchanger 108 that exchanges heat between the indoor air sent by an indoor fan 109 and a refrigerant, and performs cooling or heating to make the room comfortable.

[0071] FIG. 1 shows the cooling operation, in which the refrigerant discharged from the compressor 102 passes through the four-way valve 103 and flows into the second outdoor heat exchanger 104G, but during heating operation, the four-way valve 103 switches and the refrigerant discharged from the compressor 102 passes through the four-way valve 103 and flows into the indoor heat exchanger 108.

[0072] Furthermore, the outdoor unit 101 is provided with a gas-liquid separator 110 midway through the outdoor heat exchanger 104, with a second outdoor heat exchanger 104G between the gas-liquid separator 110 and the four-way valve 103, and a first outdoor heat exchanger 104L between the gas-liquid separator 110 and the expansion valve 106H.

[0073] The liquid refrigerant separated in the gas-liquid separator 110 is reduced in pressure and expanded in the sub-expansion valve 111, and evaporates in the refrigerant heat exchanger 112 by heat exchange with the refrigerant flowing between the expansion valve 106H and the expansion valve 106C. The liquid refrigerant is then guided to the suction port of the compressor 102 via the accumulator 113.

[0074] At this time, in cooling operation, the expansion valve 106H is fully opened and the expansion valve 106C is controlled, whereas in heating operation, the expansion valve 106C is fully opened and the expansion valve 106H is controlled, which is more effective and facilitates control.

[0075] Furthermore, a liquid-gas heat exchanger 114 is provided within the accumulator 113, and is configured to exchange heat with the refrigerant flowing between the expansion valve 106H and the expansion valve 106C.

[0076] As regulations become stricter from the standpoint of protecting the ozone layer and preventing global warming, the working refrigerants used in air conditioning generally include hydrofluorocarbons (HFCs), such as R32, which has a relatively low global warming potential, and hydrofluoroolefins (HFOs), which decompose easily in the atmosphere and have a low global warming potential.

[0077] Specific examples of promising HFOs include R1234yf, R1234ze, HFO1123, HFO1132a, and HFO1132e.

[0078] However, all of these refrigerants are man-made chemical products that contain fluorine, which can produce toxic gases such as highly corrosive hydrogen fluoride and halocarbonyl gases when decomposed by heat. Therefore, there is a strong demand for refrigerants that do not contain halogen elements such as chlorine and fluorine.

[0079] Examples of refrigerants that do not contain halogen elements include natural refrigerants such as carbon dioxide, hydrocarbons, and ammonia. However, ammonia is toxic and therefore difficult to use in general, and carbon dioxide has physical properties as a refrigerant that are not suitable for air conditioning, and in addition to its poor performance, the operating pressure is very high, which increases the input of materials and costs in order to ensure pressure resistance.

[0080] Among hydrocarbons, propane and isobutane have excellent thermophysical properties as refrigerants for air conditioning, but safety measures are essential because they are flammable.

[0081] In addition, HFO1123 and other substances may undergo self-decomposition reactions, and may pose a risk of explosion under certain conditions, such as high temperature and pressure.

[0082] As a measure against flammability in hydrocarbons and against the self-decomposition reactions in some HFOs, solutions are being sought to solve the problem by mixing refrigerants, such as a method of reducing the flammability of the refrigerant used by mixing it with a non-flammable or slightly flammable refrigerant, or a method of suppressing the self-decomposition reaction by mixing it with another refrigerant that does not undergo a self-decomposition reaction.

[0083] Additionally, many proposals have been made regarding structural measures to prevent leakage, leakage detection, and equipment-side measures such as risk avoidance actions when a leakage is detected.

[0084] Taking into consideration these requirements for refrigerant selection, the working refrigerant of the air conditioner shown in FIG. 1 is a mixture of two or more refrigerants with different boiling points, for example a refrigerant containing HFO1123 and propane.

[0085] The number of types of refrigerants to be mixed is not limited to two, but may be three or four types of refrigerants.

[0086] In the case of a mixture of HFO1123 and propane, propane is the high boiling point refrigerant and HFO1123 is the low boiling point refrigerant.

[0087] HFO1123 has a global warming potential of 1, while propane has a global warming potential of 3, making them superior in terms of protecting the ozone layer and preventing global warming.

[0088] The boiling point of a refrigerant used in air conditioning is preferably around -60°C to -30°C. The boiling point of HFO1123 is -59°C, and the boiling point of propane is -42°C, both of which are suitable for air conditioning.

[0089] However, HFO1123 is a fluorocarbon that contains fluorine and has the drawback of undergoing self-decomposition reactions. Propane is highly flammable, making it difficult to ensure safety in the event of a leak.

[0090] On the other hand, propane is excellent at suppressing the self-decomposition reaction of HFO1123, so it can be used safely by simply mixing in a small amount.

[0091] Furthermore, HFO1123 is slightly flammable, and mixing it with propane can reduce the flammability of propane.

[0092] When a mixed refrigerant of HFO1123 and propane is used as the working refrigerant, HFO1123 is more easily gasified than propane in a gas-liquid two-phase state, so compared to the component ratios of the refrigerants sealed in the device, the gas phase will have a higher ratio of HFO1123 and the liquid phase will have a higher ratio of propane.

[0093] The air conditioner shown in FIG. 1 is provided with refrigerant storage means, which include first refrigerant storage means and second refrigerant storage means.

[0094] The first refrigerant storage means is provided midway through the outdoor heat exchanger and stores the liquid refrigerant condensed in the outdoor heat exchanger during cooling operation. Here, "midway through the outdoor heat exchanger" refers to the portion in the two-phase state where the gas refrigerant compressed by the compressor during cooling operation starts to condense and becomes completely liquid.

[0095] The second refrigerant storage means is provided in front of the compressor suction port and stores the refrigerant that flows in liquid state and does not completely evaporate in the indoor unit during cooling operation, or in the outdoor heat exchanger during heating operation.

[0096] In the air conditioner shown in Fig. 1, a gas-liquid separator 110 is provided as a first refrigerant storage means, and an accumulator 113 is provided as a second refrigerant storage means, and the structure is such that liquid refrigerant is stored. Propane is stored in the liquid pools of the gas-liquid separator 110 and the accumulator 113. As a result, the composition of the refrigerant flowing in the indoor unit 107 has a lower propane ratio than the charged composition. Therefore, if a leak occurs in the indoor unit 107, the risk of ignition can be reduced.

[0097] The inter-refrigerant heat exchange means is a heat exchange means for exchanging heat between refrigerants flowing in a refrigeration or heat pump cycle, and the first inter-refrigerant heat exchange means evaporates the liquid refrigerant stored in the gas-liquid separator 110, which is the first refrigerant storage means, during cooling operation and cools the refrigerant that has flowed out of the first outdoor heat exchanger 104L, and is the inter-refrigerant heat exchanger 112 in Fig. 1. The second inter-refrigerant heat exchange means heats the refrigerant in the accumulator 113 with the refrigerant that has flowed from the first outdoor heat exchanger 104L through the inter-refrigerant heat exchanger 112 during cooling operation, and with the refrigerant that has flowed from the indoor heat exchanger 108 during heating operation, and is the liquid-gas heat exchanger 114 in Fig. 1.

[0098] FIG. 2 is a schematic diagram of the gas-liquid separator 110, which has a first connection port 110L at the top of the gas-liquid separator 110 connected to the first outdoor heat exchanger 104L, a sub-expansion valve 111 at the bottom and a liquid refrigerant discharge port 110H leading to the refrigerant-to-refrigerant heat exchanger 112, and a second connection port 110G at a specified position between them that connects to the second outdoor heat exchanger 104G.

[0099] During cooling operation, high-pressure refrigerant in a gas-liquid two-phase state that has been partially condensed in the second outdoor heat exchanger 104G flows in through the second connection port 110G, liquid refrigerant 117 is stored below the second connection port 110G, liquid refrigerant flows out from the liquid refrigerant discharge port 110H to the sub-expansion valve 111, and high-pressure gas refrigerant 118 that has not yet condensed flows out from the first connection port 110L to the first outdoor heat exchanger 104L.

[0100] When a non-azeotropic refrigerant mixture condenses, the liquid refrigerant contains a large amount of high boiling point components, but because high boiling point refrigerants condense at a higher temperature than low boiling point components under a certain pressure, the liquid refrigerant immediately after condensation begins contains a particularly large amount of high boiling point components. Therefore, it is possible to store a larger amount of high boiling point components by separating the liquid refrigerant during the condensation process than by separating the liquid from the refrigerant after condensation.

[0101] The stored liquid refrigerant is then decompressed and expanded by the sub-expansion valve 111, evaporated in the refrigerant heat exchanger 112, and returned to the suction port of the compressor 102 via the accumulator 113.

[0102] The liquid refrigerant containing a large amount of high boiling point components cools the refrigerant heading to the indoor unit 107 in the refrigerant-to-refrigerant heat exchanger 112 and bypasses the indoor unit 107, so even if the amount of liquid refrigerant stored in the gas-liquid separator 110 is small, the amount of high boiling point components flowing through the indoor unit 107 can be reduced.

[0103] Furthermore, the amount of high-boiling-point refrigerant circulating, which causes pressure loss, is reduced, resulting in improved operating efficiency.

[0104] Because a mixed refrigerant of HFO1123 and propane is used, the self-decomposition reaction of HFO1123 is suppressed and the amount of highly flammable propane flowing through the indoor unit 107 can be reduced, so that even if a leak occurs, the risk of fire is reduced and air conditioning can be performed safely.

[0105] Here, the same effect can be obtained by using HFO1132a and HFO1132e instead of HFO1123.

[0106] Even if the refrigerant used is not a mixed refrigerant of HFO1123 and propane, for example, a mixed refrigerant of R32 (boiling point -52°C) and R1234yf (boiling point -30°C) is used, the total amount of refrigerant circulating through the indoor unit 107 is reduced, and the amount of R1234yf circulating, which has a large pressure loss, is greatly reduced, thereby greatly improving pressure loss. Furthermore, by circulating a large amount of R32, which has excellent heat transfer characteristics, through the indoor unit 107, the operating efficiency is greatly improved.

[0107] During heating operation, low-pressure, two-phase gas-liquid refrigerant that has partially evaporated in the first outdoor heat exchanger 104L flows in through the first connection port 110L, liquid refrigerant is stored below the second connection port 110G, liquid refrigerant flows out from the liquid refrigerant discharge port 110H, and low-pressure, two-phase gas-liquid refrigerant flows out from the second connection port 110G to the second outdoor heat exchanger 104G.

[0108] Even during heating operation, liquid refrigerant can be stored in the gas-liquid separator 110, and the amount of high boiling point components flowing through the indoor unit 107 can be reduced.

[0109] In other words, in heating, as in cooling, the amount of highly flammable propane flowing through the indoor unit 107 is reduced, so that even if there is a leak, the risk of fire can be reduced and air conditioning can be performed safely.

[0110] Furthermore, the total amount of refrigerant flowing through the second outdoor heat exchanger 104G, where the amount of evaporated gas-phase refrigerant increases and pressure loss is likely to occur, particularly the flow rate of propane, which is likely to cause pressure loss, is reduced, thereby improving pressure loss and improving operating efficiency.

[0111] FIG. 3 is a schematic diagram of accumulator 113 and liquid-gas heat exchanger 114 in the first embodiment of the present invention.

[0112] The refrigerant after leaving the evaporator (the indoor heat exchanger 108 during cooling, and the first outdoor heat exchanger 104L and the second outdoor heat exchanger 104G during heating) flows into the accumulator 113 from the accumulator inlet pipe 113A and is separated into a gas phase and a liquid phase, and the gas phase refrigerant flows out from the accumulator outlet pipe 113B toward the suction port of the compressor 102. An oil return hole 301 is provided in the accumulator outlet pipe 113B near the bottom of the accumulator 113 to prevent malfunctions caused by oil from the compressor 102 staying inside the accumulator 113.

[0113] Since low boiling point components of the refrigerant tend to evaporate in the evaporator, the ratio of high boiling point components increases in the liquid refrigerant stored in the accumulator 113. Therefore, storing liquid refrigerant in the accumulator 113 leads to efficient storage of high boiling point components, and similar to the effect of the gas-liquid separator 110, improved operating efficiency and improved safety can be easily achieved.

[0114] Furthermore, a liquid-gas heat exchanger 114 made of a refrigerant pipe processed into a coil shape is provided inside the accumulator 113, and a connection port 114H on the refrigerant-to-refrigerant heat exchanger side is connected to the refrigerant-to-refrigerant heat exchanger 112, and a connection port 114E on the expansion valve 106C side is connected to the expansion valve 106C.

[0115] By exchanging heat with the liquid-gas heat exchanger 114, it is possible to improve the deterioration of performance due to temperature slippage and pressure loss.

[0116] The surface of the liquid-gas heat exchanger 114 comes into contact with the refrigerant inside the accumulator 113. Since the heat transfer coefficient of liquid is greater than that of gas, the amount of heat exchange is small when the surface comes into contact with the gas refrigerant and large when the surface comes into contact with the liquid refrigerant.

[0117] Therefore, when the amount of liquid refrigerant stored in the accumulator 113 is small and the liquid refrigerant does not come into contact with the liquid-gas heat exchanger 114, the amount of heat exchange in the liquid-gas heat exchanger 114 is small and the effect of internal heat exchange is small, but it becomes easier to increase the amount of stored liquid refrigerant.

[0118] As the amount of stored liquid refrigerant increases and the liquid refrigerant starts to come into contact with the liquid-gas heat exchanger 114, the amount of heat exchange increases and the effect of internal heat exchange also increases. Then, the increase in the amount of stored liquid refrigerant is suppressed, making it easier to keep the amount of stored liquid refrigerant constant.

[0119] The height at which the liquid-gas heat exchanger 114 is disposed can be set according to the expected amount of liquid refrigerant stored, thereby realizing the desired performance and amount of refrigerant charged.

[0120] In addition, in FIG. 3, the liquid-gas heat exchanger 114 is in the form of a refrigerant pipe processed into a coil shape, but this is not limited to this form, and the same function can be performed even if it is in a form consisting of a tube through which a refrigerant flows and heat dissipation fins, or in a jacket-like form with a refrigerant flow path.

[0121] In FIG. 1, the positional relationship between the refrigerant-to-refrigerant heat exchanger 112 and the liquid-to-gas heat exchanger 114 is such that the refrigerant-to-refrigerant heat exchanger 112 is disposed on the side of the expansion valve 106H, and the liquid-to-gas heat exchanger 114 is disposed on the side of the expansion valve 106C, but is not limited to this arrangement.

[0122] As described above, the air conditioner in the first embodiment is a device that uses a non-azeotropic refrigerant mixture containing a refrigerant having high flammability or combustibility as a high boiling point refrigerant, and is equipped with a refrigerant storage means for storing the working refrigerant in the outdoor unit.The refrigerant storage means stores a high boiling point refrigerant having high flammability or combustibility, and the refrigerant is circulated in the main refrigerant circulation circuit with a high ratio of low boiling point components, so that even if a refrigerant leak occurs in the indoor unit, the risk of ignition is reduced, providing an air conditioner with excellent safety.

[0123] Furthermore, the present invention provides an air conditioner which uses a hydrocarbon as a highly flammable or combustible refrigerant and which has a small effect on global warming.

[0124] Furthermore, the present invention uses propane or isobutane as the hydrocarbon refrigerant, which is suitable for air conditioning in terms of evaporation temperature and thermal properties and is easy to procure, thereby providing an air conditioner that is inexpensive and has excellent operating efficiency.

[0125] Furthermore, the air conditioner uses at least one of HFO1123, HFO1132a, and HFO1132e as a low-boiling point component, which have a small global warming potential and are suitable for air conditioning in terms of evaporation temperature and thermal properties, thereby providing an air conditioner that is excellent at suppressing global warming.

[0126] In addition, the air conditioner in embodiment 1 uses a non-azeotropic refrigerant mixture, and a first refrigerant storage means is provided midway through the outdoor heat exchanger. The liquid refrigerant stored in the first refrigerant storage means is drawn off and guided to the compressor suction port via a first refrigerant heat exchange means which cools the circulating refrigerant on the condensed liquid side. By storing the liquid refrigerant, the ratio of high boiling point refrigerant flowing in the main refrigerant circuit is reduced, and the amount of working refrigerant flowing through the evaporator outlet is reduced to reduce pressure loss, thereby providing an air conditioner with excellent operating efficiency.

[0127] Furthermore, a gas-liquid separator is used for the first refrigerant storage means, and a first connection port connecting to the first outdoor heat exchanger is provided at the top, a liquid refrigerant discharge port connecting to the first refrigerant heat exchange means is provided at the bottom, and a second connection port connecting to the second outdoor heat exchanger is provided between the first connection port and the liquid refrigerant discharge port, thereby efficiently separating the liquid refrigerant and gas refrigerant and storing the liquid refrigerant between the liquid refrigerant discharge port and the gas side connection port, thereby providing an air conditioner with excellent operating efficiency.

[0128] In addition, the air conditioner in embodiment 1 uses a non-azeotropic refrigerant mixture, and is equipped with a second refrigerant storage means for storing the working refrigerant before the suction port of the compressor, and a second refrigerant-to-refrigerant heat exchange means for exchanging heat between the refrigerant stored inside the second refrigerant storage means and the circulating refrigerant on the condensate side. The second refrigerant storage means stores a refrigerant with a high boiling point that causes performance degradation, and the main refrigerant circulation circuit has a high ratio of refrigerant with low boiling point components that have superior performance. By exchanging refrigerant heat before the suction port of the compressor with the refrigerant that has left the outdoor heat exchanger during cooling operation, and with the refrigerant that has left the indoor heat exchanger during heating operation, performance degradation due to temperature slippage and pressure loss is suppressed, and an air conditioner with excellent operating efficiency is provided.

[0129] Furthermore, the accumulator serves as a second refrigerant storage means, and the liquid-gas heat exchanger serves as a second refrigerant heat exchange means, and the liquid-gas heat exchanger is disposed at a predetermined height within the accumulator.This provides an air conditioner that can operate stably because liquid refrigerant is reliably stored in the space below the liquid-gas heat exchanger and the liquid refrigerant storage level can be easily maintained. [Industrial Applicability]

[0130] As described above, the air conditioner of the present invention provides a safe and efficient device by storing liquid refrigerant when using a non-azeotropic refrigerant mixture, and this technology is not limited to air conditioners, but can also be widely applied and is effective in water heaters, showcases, freezers, etc. [Explanation of symbols]

[0131] 101 Outdoor unit 102 Compressor 103 Four-way valve 104 Outdoor heat exchanger 104G Second outdoor heat exchanger 104L First outdoor heat exchanger 105 Outdoor fan 106C Expansion valve (for cooling) 106H Expansion valve (for heating) 107 Indoor unit 108 Indoor heat exchanger 109 Indoor Fan 110 Gas-liquid separator 111 Sub-expansion valve 112 Refrigerant heat exchanger 113 Accumulator 114 Liquid-gas heat exchanger 115 Liquid side connection valve 116 Gas side connection valve

Claims

1. an outdoor unit having a compressor that compresses and delivers a working refrigerant, and an outdoor heat exchanger that exchanges heat between outdoor air sent by an outdoor blower and the working refrigerant; an indoor unit having an indoor heat exchanger for exchanging heat between the working refrigerant and indoor air sent by an indoor blower; An air conditioner that constitutes a refrigeration or heat pump cycle, A mixture of at least two or more kinds of refrigerants having different boiling points is used as the working refrigerant, a refrigerant having high flammability or combustibility is used as the high boiling point refrigerant of the working refrigerant, and a refrigerant storage means for storing a liquid of the working refrigerant is provided in the outdoor unit, The refrigerant storage means is a first refrigerant storage means for storing the working refrigerant in the middle of the outdoor heat exchanger, and the liquid refrigerant stored in the first refrigerant storage means is led out and led to a suction port of the compressor via a first refrigerant heat exchange means for cooling a circulating refrigerant on a condensed liquid side; an expansion valve for reducing the pressure of a refrigerant and expanding the refrigerant, the expansion valve being disposed between the indoor heat exchanger side of the outdoor heat exchanger and the first refrigerant heat exchange means.

2. an outdoor unit having a compressor that compresses and delivers a working refrigerant, and an outdoor heat exchanger that exchanges heat between outdoor air sent by an outdoor blower and the working refrigerant; an indoor unit having an indoor heat exchanger for exchanging heat between the working refrigerant and indoor air sent by an indoor blower; An air conditioner that constitutes a refrigeration or heat pump cycle, A mixture of at least two or more kinds of refrigerants having different boiling points is used as the working refrigerant, a refrigerant having high flammability or combustibility is used as the high boiling point refrigerant of the working refrigerant, and a refrigerant storage means for storing a liquid of the working refrigerant is provided in the outdoor unit, the refrigerant storage means is a second refrigerant storage means for storing the working refrigerant in front of a suction port of the compressor, and includes a second refrigerant heat exchange means for exchanging heat between the refrigerant stored inside the second refrigerant storage means and a circulating refrigerant on a condensate side; an expansion valve for reducing the pressure of a refrigerant and expanding the refrigerant, the expansion valve being disposed between the indoor heat exchanger side of the outdoor heat exchanger and the second refrigerant heat exchange means.

3. 3. The air conditioner according to claim 1, wherein the high boiling point refrigerant of the working refrigerant is a hydrocarbon.

4. 4. The air conditioner according to claim 3, wherein the hydrocarbon is propane or isobutane.

5. The air conditioner according to any one of claims 1 to 4, characterized in that at least one of 1,1,2-trifluoroethylene (HFO1123), 1,1-difluoroethylene (HFO1132a), and trans-1,2-difluoroethylene (HFO1132e) is used as the low boiling point refrigerant of the working refrigerant.

6. 2. The air conditioner according to claim 1, wherein the first refrigerant storage means is a gas-liquid separator having a first connection port at an upper portion thereof connected to the first outdoor heat exchanger, a liquid refrigerant discharge port at a lower portion thereof connected to the first refrigerant-to-refrigerant heat exchange means, and a second connection port at a position between the first connection port and the liquid refrigerant discharge port thereof connected to a second outdoor heat exchanger.

7. 3. The air conditioner according to claim 2, wherein the second refrigerant storage means is an accumulator, and the second refrigerant heat exchange means is disposed at a predetermined height within the second refrigerant storage means.

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