JP2014035171A - Air conditioner, air conditioning method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a further improved air conditioner, an air conditioning method and a program.SOLUTION: An air conditioner 10 includes: a refrigeration cycle circuit 100 provided with a channel 30a which comprises combustible HFC and in which a cooling medium circulates and an indoor heat exchanger 31 which is connected to the channel 30a and which performs heat exchange with air by evaporating or condensing the cooling medium; a blower 32 which supplies the air heat-exchanged by the indoor heat exchanger 31 to space R which is an air conditioning object; an oxygen concentration sensor 33 which is used for detecting leak of the cooling medium from the refrigeration cycle circuit 100; and a control unit 40. The control unit 40 controls the refrigeration cycle circuit 100 and the blower 32 so that absolute humidity of the indoor space R becomes low by performing a dehumidification operation of the indoor air, when the leak of the cooling medium is detected by the oxygen concentration sensor 33.

Description

  The present invention relates to an air conditioner, an air conditioning method, and a program using a flammable HFC refrigerant.

  Currently, an HFC refrigerant such as R410A is used as a refrigerant in a refrigeration cycle apparatus typified by an air conditioner. Unlike conventional HCFC refrigerants such as R22, R410A has zero ozone depletion potential ODP (Ozone Depletion Potential) and does not destroy the ozone layer, but has a global warming potential GWP (Global Warming Potential). It has the property of being high. Therefore, as part of the prevention of global warming, studies are underway to change from an HFC refrigerant with a high GWP such as R410A to an HFC refrigerant with a low GWP.

  A candidate for a low GWP HFC refrigerant is R32 (CH2F2; difluoromethane). As candidate refrigerants having the same characteristics, halogenated hydrocarbons having a carbon triple bond in the composition, such as HFO-1234yf (CF3CF = CH2; tetrafluoropropane) and HFO-1234ze (CF3-CH = CHF), are used. is there. Although these are a kind of HFC refrigerant like R32, since unsaturated hydrocarbons having carbon double bonds are called olefins, HFC refrigerants that do not have carbon double bonds in the composition like R32 In order to distinguish, it is often expressed as HFO using O of olefin.

  Although such low GWP HFC refrigerants (including HFO refrigerants) are not as flammable as HC refrigerants such as R290 (C3H8; propane), they are less flammable than R410A, which is nonflammable. Therefore, it is necessary to pay attention to refrigerant leakage. Hereinafter, the flammable refrigerant is referred to as a flammable refrigerant.

  With respect to such a problem of refrigerant leakage, Patent Document 1 discloses that when refrigerant leaks in the air conditioner, the refrigerant is diffused in the room by rotating the blower fan of the air conditioner. An air conditioner that lowers the overall refrigerant concentration is disclosed.

JP 2000-81258 A

  In the air conditioner described in Patent Document 1, a relatively high concentration of refrigerant may be locally retained on the floor surface depending on the setting of the wind direction in the blowing operation. If the volume concentration of the refrigerant that stays is in the flammable concentration range, and there is any ignition source there, the flammable refrigerant ignites and burns. The scale of combustion varies depending on the type of refrigerant, and the low GWP HFC refrigerant is slightly flammable, so the scale of combustion is smaller than that of a highly flammable HC refrigerant such as propane. Here, the large combustion scale means that the reciprocal of the combustion time is large, for example, that the flame propagates quickly, the pressure rise is large, and the generated flame is large.

  From recent research and evaluation of combustion phenomena for slightly flammable HFC refrigerants that are flammable but have a smaller combustion scale than flammable refrigerants such as propane, R32 and HFO refrigerants Regarding the phenomenon, it has been found that the combustion scale tends to increase as the absolute humidity increases under the same conditions. Therefore, in a refrigeration cycle apparatus such as an air conditioner using an HFC refrigerant having a low GWP refrigerant such as R32 or HFO refrigerant and having a slightly flammable level as a refrigerant, such a correlation between the combustion scale and absolute humidity is obtained. In light of the above, although it was slightly flammable, there was a problem that it was necessary to improve the safety against refrigerant leakage.

  The present invention has been made in order to solve the above-described problems, and is safe against possible refrigerant leakage when a low-GWP but flammable HFC refrigerant such as R32 or HFO refrigerant is used as the refrigerant. An object of the present invention is to provide an air conditioner, an air conditioning method, and a program that improve the air quality.

In order to achieve the above object, an air conditioner according to the present invention includes:
A refrigeration cycle circuit comprising: a flow path through which a refrigerant composed of combustible HFC circulates; and a heat exchanger connected to the flow path to exchange heat with air by evaporating or condensing the refrigerant, and heat exchange A blower that supplies air that has been heat-exchanged by the air conditioner to a room to be air conditioned, a detection means that detects leakage of refrigerant from the refrigeration cycle circuit, and an air-conditioning target when the detection means detects leakage of refrigerant. By performing the operation of dehumidifying the indoor air, the control unit controls the refrigeration cycle circuit and the blower so as to lower the indoor absolute humidity.

  In the present invention, when a refrigerant composed of flammable HFC leaks, the absolute humidity in the room is lowered by performing an operation of dehumidifying the indoor air to be conditioned. For this reason, the combustion scale of a refrigerant | coolant can be made small. As a result, safety can be improved.

It is a mimetic diagram of an air harmony machine concerning an embodiment of the invention. It is a perspective view of an indoor unit. It is sectional drawing of an indoor unit. It is a figure which shows typically the relationship between the absolute humidity of an alternative refrigerant | coolant, and a combustion scale. It is a Mollier diagram for demonstrating operation | movement of an air conditioner. It is a flowchart for demonstrating operation | movement of an air conditioner. It is sectional drawing of the indoor unit which concerns on a modification.

  Hereinafter, the air conditioner 10 which concerns on this Embodiment is demonstrated using FIGS.

  The air conditioner 10 according to the embodiment of the present invention performs air conditioning of the room R to be air conditioned when the refrigerant flows back to the refrigeration cycle circuit 100. As shown in FIG. 1, the air conditioner 10 includes an outdoor unit 20 and an indoor unit 30. As the refrigerant, a refrigerant having a small global warming potential (GWP), for example, R32 of a hydrofluorocarbon (HFC) refrigerant is used.

  The outdoor unit 20 is installed outside a room subject to air conditioning, and includes a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, an expansion valve 24, a tubular flow path 20 a connecting the above-described parts, and a discharge temperature sensor 25. I have. The flow path 20a includes a discharge-side flow path 20b of the compressor 21, a flow path 20c near the expansion valve 24 (flow paths on the inlet side and the outlet side of the expansion valve 24), and the like. A control unit 40 is disposed in the outdoor unit 20.

  The compressor 21 is a device that compresses the supplied refrigerant, and includes, for example, a rotary compressor and a scroll compressor. The compressor 21 changes the refrigerant into a high-temperature and high-pressure refrigerant by compressing the refrigerant. Then, the compressor 21 sends the high-temperature and high-pressure refrigerant to the four-way valve 22 via the discharge-side flow path 20 b of the compressor 21. A discharge temperature sensor 25 is disposed in the flow path 20b. The discharge temperature sensor 25 measures the temperature (discharge temperature) T of the refrigerant discharged from the compressor 21. The discharge temperature T is used to stop the operation of the refrigeration cycle when the amount of refrigerant remaining in the refrigeration cycle circuit 100 decreases. In the present embodiment, the discharge temperature sensor 25 is disposed in the discharge-side flow path 20b of the compressor 21, but is not limited thereto, and is disposed on a container (shell) of the compressor 21. May be.

  The four-way valve 22 is provided on the downstream side of the compressor 21. The four-way valve 22 switches between the heating operation cycle and the cooling operation cycle by switching the refrigerant recirculation direction. The four-way valve 22 is controlled by the control unit 40.

  The outdoor heat exchanger 23 performs heat exchange with the air by evaporating or condensing the inflowing refrigerant, thereby cooling or heating the air. For example, during the cooling operation, the outdoor heat exchanger 23 functions as a condenser and condenses the refrigerant that has flowed in. Further, during the heating operation, the outdoor heat exchanger 23 functions as an evaporator to evaporate the refrigerant that has flowed.

  The expansion valve 24 expands the flowing refrigerant. At this time, the refrigerant undergoes isoenthalpy expansion and changes to a low-pressure refrigerant. The expansion valve 24 delivers the generated low-pressure refrigerant through the flow path 20c.

  The compressor 21, the four-way valve 22, the outdoor heat exchanger 23, and the expansion valve 24 described above are accommodated in a metal casing.

  The indoor unit 30 is installed in a room R subject to air conditioning, and includes an indoor heat exchanger 31, a blower 32, an oxygen concentration sensor 33, an absolute humidity sensor 34, a room temperature sensor 50, and a flow path 30a. Yes. The flow path 30a connects the indoor heat exchanger 31 to the compressor 21 and the expansion valve 24 of the outdoor unit 20.

  FIG. 2 is a perspective view of the indoor unit 30. In FIG. 2, the Y-axis direction is the longitudinal direction of the indoor unit 30, and the Z-axis direction is the vertical direction. As illustrated in FIG. 2, the above-described members (the indoor heat exchanger 31, the blower 32, the oxygen concentration sensor 33, and the absolute humidity sensor 34 illustrated in FIG. 1) are covered with a casing 35. The housing 35 has a longitudinal direction in the Y-axis direction, and a blower outlet 35a for supplying cold air or hot air is formed below the front panel of the housing 35. Further, a suction port 35 b for sucking air in the room R is formed on the upper surface of the housing 35. In addition, an opening 35 c for taking in air in the room R is formed on the side surface (side surface on the + Y side) of the housing 35. Near the opening 35c, an absolute humidity sensor 34 and a room temperature sensor 50 described later are attached. By attaching the absolute humidity sensor 34 and the room temperature sensor 50 in the vicinity of the opening 35c, the absolute humidity and room temperature of the room R can be accurately measured.

  FIG. 3 is a cross-sectional view of the indoor unit 30. The indoor heat exchanger 31 is arrange | positioned so that the upper direction of the air blower 32 may be covered, as shown in FIG. Inside the indoor heat exchanger 31, a plurality of pipes 31a are provided. As the refrigerant passes through the pipe 31a, the indoor heat exchanger 31 exchanges heat with the surrounding air to cool or heat the refrigerant. For example, during the cooling operation, the indoor heat exchanger 31 functions as an evaporator to evaporate the refrigerant that has flowed. Thereby, the indoor heat exchanger 31 absorbs heat from the air around the indoor heat exchanger 31 and cools the surrounding air. Further, during the heating operation, the indoor heat exchanger 31 functions as a condenser and condenses the inflowing gaseous refrigerant. Thereby, the indoor heat exchanger 31 releases heat to the air around the indoor heat exchanger 31, and heats the surrounding air.

  In the present embodiment, refrigeration is performed by the indoor heat exchanger 31, the flow path 30a, the compressor 21, the four-way valve 22, the outdoor heat exchanger 23, the expansion valve 24, the discharge temperature sensor 25, and the like of the outdoor unit 20 described above. A cycle circuit is configured.

  Under the indoor heat exchanger 31 (-Z side), condensed water receiving portions 36A and 36B are formed. The condensed water receiving portions 36A and 36B are trays that receive water droplets condensed by heat exchange of the indoor heat exchanger 31 during cooling operation or dehumidifying operation. The condensed water receiving part 36A and the condensed water receiving part 36B are connected by a water channel (not shown), and the condensed water received by the condensed water receiving part 36B flows into the condensed water receiving part 36A. Then, the condensed water collected in the condensed water receiving portion 36A is drained to the outside of the room R through a water distribution pipe or the like.

  The blower 32 includes a blower fan and a fan motor that rotates the blower fan. The blower 32 supplies the air that has been heat-exchanged by the indoor heat exchanger 31 to the room R to be air-conditioned by the rotation of the blower fan. In the present embodiment, the blower 32 is configured by a cross flow fan. A plurality of wind direction plates 37 are attached to the air outlet 35 a of the housing 35. The wind direction plate 37 defines the supply direction (wind direction) of air from the blower 32 and is supported so as to be rotatable with respect to the Y-axis direction. Air from the blower 32 passes through an air passage 38 formed on the lower side (−Z side) of the blower 32 and is guided by the wind direction plate 37 in the horizontal direction (the direction indicated by the arrow W3 in FIG. 3). The air is blown out in the direction of the floor surface of the room R or in the diagonally upward direction (the direction indicated by the arrow W4 in FIG. 3).

  The oxygen concentration sensor 33 measures the oxygen concentration C in the housing 35 of the indoor unit 30. The oxygen concentration C is used to detect refrigerant leakage from the refrigeration cycle circuit 100. Since the oxygen concentration contained in the air is usually 20.95%, when the refrigerant is mixed into the air, the oxygen concentration is reduced accordingly. For example, if the refrigerant is mixed up to 14.4% in the air, the ratio of the air in the mixed gas (air mixed with the refrigerant) is reduced to 85.6% (= 100% -14.4%) Relatively, the oxygen concentration decreases to 17.93% (= 85.6% × 0.2095). Therefore, the control unit 40, for example, has an oxygen concentration C that is less than or equal to a preset set value Cs (for example, 18.7% or less. This is an oxygen concentration that is estimated to be slightly larger than 17.93% described above. .), It is determined that the refrigerant has leaked from the refrigeration cycle circuit 100.

  The oxygen concentration sensor 33 is disposed in the vicinity of the condensed water receiving portion 36A. Since the specific gravity of the refrigerant is larger than that of air, when the refrigerant leaks from the indoor heat exchanger 31, it stays in the condensed water receiving portion 36A. Therefore, the oxygen concentration sensor 33 is disposed in the vicinity of the condensed water receiving portion 36A where the leaked refrigerant is likely to accumulate. The oxygen concentration sensor 33 is supported by a frame portion of the condensed water receiving portion 36A via a bracket or the like so as not to touch the condensed water accumulated in the condensed water receiving portion 36A. Thereby, the oxygen concentration sensor 33 touches the condensed water collected in the condensed water receiving part 36A, and the detection accuracy is prevented from being lowered. Moreover, the oxygen concentration sensor 33 is arrange | positioned in the center vicinity of the longitudinal direction (Y-axis direction shown by FIG. 2) of the air conditioner 10, for example, as shown in FIG. However, the present invention is not limited to this, and the oxygen concentration sensor 33 may be disposed at a place other than the vicinity of the center. Also, a plurality of oxygen concentration sensors 33 may be arranged to calculate the average value of the oxygen concentration measured by each.

For example, as can be seen with reference to FIG. 3, the absolute humidity sensor 34 is arranged on the upstream side of the flow of the indoor air passing through the indoor heat exchanger 31 so as to touch the indoor air sucked from the suction port 35 b. Yes. Further, the absolute humidity sensor 34 is arranged at a predetermined distance from the indoor heat exchanger 31 so as not to be affected by heat exchange performed by the indoor heat exchanger 31. The absolute humidity sensor 34 measures the absolute humidity H of the room R subject to air conditioning. In the air conditioner 10 according to the present embodiment, as described above, a low GWP HFC refrigerant (here, R32) that is effective in preventing global warming is used as the refrigerant flowing through the refrigeration cycle circuit 100. Since such an HFC refrigerant is slightly flammable, the air conditioner 10 needs to have high safety against any possible refrigerant leakage. As a result of repeated analysis of such a low GWP HFC refrigerant (alternative refrigerant) effective for preventing global warming, the inventor has obtained an absolute humidity H (g / m ³ ) and an alternative refrigerant as shown in FIG. It has been found that there is a predetermined correlation with the combustion scale (1 / s, reciprocal of combustion time) when igniting. FIG. 4 is a diagram schematically showing the relationship between absolute humidity H (g / m ³ ) and the combustion scale (1 / s, reciprocal of combustion time) when the alternative refrigerant is ignited.

  Specifically, as shown in FIG. 4, these low GWP but slightly flammable HFC refrigerants (R32, HFO) are the same except for absolute humidity, based on recent research on these refrigerants, particularly the evaluation of the combustion scale. It was found that the combustion scale tends to increase as the absolute humidity increases under the conditions (when the same ignition source is used with the same refrigerant type and the same refrigerant gas concentration).

  In the evaluation of the HFC refrigerant (R32, HFO), for example, it was performed as follows. First, refrigerant gas is enclosed in an experimental box, and at that time, the refrigerant gas concentration in the box is in a combustible region (14.4 vol% to 29.3 vol% if R32, 6.2 vol% if HFO-1234yf). 12.3 vol%) is encapsulated in an amount such that a certain value is obtained, and the refrigerant gas concentration distribution in the box is made uniform with a stirring fan installed in the box.

  Then, the nichrome wire heater installed in the box is energized, and the heater is heated until the refrigerant in the experimental box is ignited. Observe the process from igniting and burning the refrigerant until it stops spontaneously. Also, evaluate the combustion range, combustion time, pressure rise, etc., and judge the size of the combustion scale. The absolute humidity in the experimental box is measured by an absolute humidity sensor, and confirmation that the refrigerant gas concentration is the same is made by confirming that the oxygen concentration in the box is the same with an oximeter.

  When the evaluation of such a slightly flammable HFC refrigerant was performed a plurality of times using the absolute humidity in the experimental box as a parameter, as shown in FIG. 4, the larger the absolute humidity, the larger the combustion scale tends to be. It was found. The absolute temperature is changed according to the weather, the season and the time of the day. From the results obtained in this evaluation, in the situation where the absolute temperature is lower, the R32 or HFO refrigerant whose refrigerant concentration with respect to the air is in the flammable region is provided with a fire type for some reason (the ignition source exists). ) In the event of ignition, the idea can be derived that the scale of combustion can be reduced and the safety against refrigerant leakage should be increased.

In summary, under the same conditions except for absolute humidity (when ignited with the same refrigerant type, the same refrigerant gas concentration, and the same ignition source), the combustion scale decreases as the absolute humidity of the alternative refrigerant decreases. Become. Here, the large combustion scale means that the reciprocal of the combustion time is large, for example, that the propagation of the flame is fast, the pressure rise is large, and the generated flame is large. That is, if the absolute humidity H of the alternative refrigerant is reduced, the combustion scale when the refrigerant is ignited is reduced, and the combustibility of the refrigerant can be weakened. In the present embodiment, the air conditioner 10 performs a cooling operation or a dehumidifying operation that lowers the absolute humidity H in the room R so that the absolute humidity H measured by the absolute humidity sensor 34 is equal to or less than the set value Hs. . This set value Hs is a threshold value that is considered to be sufficient for ensuring the safety of the user even if the refrigerant burns, and is, for example, 10.0 g / m ³ .

  Moreover, the absolute humidity sensor 34 is arrange | positioned in the back side vicinity of the opening 35c formed in the side surface of the housing | casing 35, as shown in FIG. When the blower fan of the blower 32 rotates, the air in the room R is taken from the opening 35c of the housing 35, and thus the absolute humidity sensor 34 can accurately measure the absolute humidity H in the room R.

  An abnormality display lamp 39 is provided on the front surface of the housing 35 of the indoor unit 30. For example, the abnormality display lamp 39 blinks when refrigerant leakage is detected, thereby notifying the user of the air conditioner 10 that refrigerant has leaked.

  As shown in FIG. 1, the flow path 20 a of the outdoor unit 20 configured as described above and the flow path 30 a of the indoor unit 30 are connected by a connection pipe 11 and a flare nut 12. With the connection pipe 11 and the flare nut 12, the refrigeration cycle circuit 100 is configured as a circuit sealed from the outside. A shutoff valve 13 is provided in the flow path of the outdoor unit 20. The closing valve 13 closes or opens the refrigerant flow in the refrigeration cycle circuit 100.

  The control unit 40 includes a central processing unit (CPU), a main storage unit, an auxiliary storage unit, and a bus that interconnects the above units. The main storage unit of the control unit 40 is composed of a RAM (Random Access Memory) or the like and used as a work area for the CPU. The auxiliary storage unit includes a nonvolatile memory such as a ROM (Read Only Memory) and a semiconductor memory. The auxiliary storage unit of the control unit 40 stores programs executed by the CPU, various parameters, and the like.

  As shown in FIG. 1, an oxygen concentration sensor 33, an absolute humidity sensor 34, and a discharge temperature sensor 25 are connected to the control unit 40 via a cable or the like. The control unit 40 receives the oxygen concentration C from the oxygen concentration sensor 33, a signal indicating the absolute humidity H from the absolute humidity sensor 34, and the discharge temperature T from the discharge temperature sensor 25. Then, the CPU of the control unit 40 is notified of the oxygen concentration C, the absolute humidity H, and the discharge temperature T.

  The control unit 40 is connected to the four-way valve 22 and the fan motor of the blower 32. The control unit 40 controls the four-way valve 22 to switch the refrigerant recirculation direction based on an instruction from the CPU. In addition, the control unit 40 applies a voltage corresponding to the number of rotations in order to control the rotation of the blower fan of the blower 32 based on an instruction from the CPU.

  The CPU of the control unit 40 executes a program stored in the auxiliary storage unit and performs overall control of the above-described units. In addition, although the control unit 40 is arrange | positioned in the outdoor unit 20 in FIG. 1, it is not restricted to this. For example, it may be composed of an outdoor control unit and an indoor control unit, and may be arranged in each of the outdoor unit 20 and the indoor unit 30. Moreover, it is arrange | positioned outside the outdoor unit 20, and may be comprised integrally with the remote control etc., for example.

  The air conditioner 10 configured as described above performs air conditioning of the room R by performing a blowing operation, a cooling operation, a dehumidifying operation, and a heating operation. The blowing operation is an operation in which air is supplied only by the blower 32 without operating the refrigeration cycle. The cooling operation, the dehumidifying operation, and the heating operation are operations for supplying cold air and hot air by the blower 32 while operating the refrigeration cycle. The operation of the refrigeration cycle during the cooling operation and the dehumidifying operation is the same. Hereinafter, the operation of the refrigeration cycle will be described with reference to FIG. 1 and FIG. 5 by taking cooling operation and dehumidifying operation as examples. In the Mollier diagram of FIG. 5, the horizontal axis indicates the enthalpy (specific enthalpy) per unit mass of the refrigerant, and the vertical axis indicates the pressure of the refrigerant.

  In the case of the cooling operation, the four-way valve 22 is switched so as to send the refrigerant from the compressor 21 to the outdoor heat exchanger 23. The outdoor heat exchanger 23 functions as a condenser, and the indoor heat exchanger 31 functions as an evaporator.

  First, when the refrigerant (the refrigerant in the state Sa in FIG. 5) flows into the compressor 21, the refrigerant that has flowed in is compressed by the compressor 21. Then, the pressure and specific enthalpy of the refrigerant rise, change to a high temperature and high pressure state (state Sb), and are sent from the compressor 21. The refrigerant sent out from the compressor 21 passes through the four-way valve 22 and flows into the outdoor heat exchanger 23.

  When the refrigerant in the state Sb flows into the outdoor heat exchanger 23, the refrigerant is condensed by heat exchange with air. Then, the specific enthalpy of the refrigerant decreases while the pressure is constant. As a result, the refrigerant changes to a liquid state (state Sc). Then, the refrigerant is sent out from the outdoor heat exchanger 23.

  When the refrigerant in the state Sc flows into the expansion valve 24, the refrigerant is expanded by the expansion valve 24. Then, the refrigerant changes from a high pressure state to a low pressure state (state Sd) while keeping the specific enthalpy constant. Then, the refrigerant is sent out from the expansion valve 24.

  When the refrigerant in the state Sd flows into the indoor heat exchanger 31, the refrigerant evaporates by heat exchange with the surrounding air. Then, the specific enthalpy of the refrigerant increases while the pressure is constant. Thereby, a refrigerant | coolant changes to the state (state Sa) of a refrigerant | coolant with a large dryness.

  At this time, as shown in FIG. 3, the air sucked from the room R through the suction port 35b of the housing 35 by the blower 32 (air flowing as indicated by the arrow W1) is the indoor heat exchanger. 31 is cooled by heat exchange with the refrigerant. The cooled air passes through the air passage 38 and is blown out from the air outlet 35a of the housing 35 as indicated by an arrow W2. As a result, the cold air is supplied to the room R.

  Returning to FIG. 1 and FIG. 5, the refrigerant (refrigerant in the state Sa) sent from the indoor heat exchanger 31 passes through the four-way valve 22 and flows into the compressor 21 again. Thereafter, the same refrigeration cycle is repeated.

  Here, when the refrigerant leaks from the refrigeration cycle circuit 100, the amount of refrigerant remaining in the refrigeration cycle circuit 100 decreases, and as shown in FIG. 5, the Mollier diagram shows the direction in which the pressure decreases and the specific enthalpy. Shift in the direction of increasing. For example, the refrigerant in the state Sb flowing out of the compressor 21 changes to the refrigerant in the state Sb ′, and the refrigerant temperature increases. The temperature of the refrigerant in the states Sb and Sb ′ is measured by the discharge temperature sensor 25 described above. In the present embodiment, when the discharge temperature T measured by the discharge temperature sensor 25 is equal to or higher than a set value Ts (for example, 120 ° C. or higher), the control unit 40 stops the operation of the refrigeration cycle.

  In the present embodiment, the dehumidifying operation is performed by operating the same refrigeration cycle as in the above-described cooling operation and by reducing the rotational speed of the blower fan of the blower 32 as compared with the cooling operation (weak cooling). Dehumidification operation).

  In the case of heating operation, the four-way valve 22 is switched so as to send the refrigerant from the compressor 21 to the indoor heat exchanger 31. In this case, the outdoor heat exchanger 23 functions as an evaporator, and the indoor heat exchanger 31 functions as a condenser. The refrigerant sent out from the compressor 21 flows into the indoor heat exchanger 31.

  When the refrigerant flows into the indoor heat exchanger 31, the refrigerant is condensed by heat exchange with the surrounding air. Then, the specific enthalpy of the refrigerant decreases while the pressure is constant. Thereby, the refrigerant changes to a liquid state. At this time, the air around the indoor heat exchanger 31 is heated by heat exchange with the refrigerant, and the heated air is supplied to the room R as warm air by the blower 32.

  The refrigerant sent from the indoor heat exchanger 31 sequentially passes through the expansion valve 24, the outdoor heat exchanger 23, and the four-way valve 22, and flows into the compressor 21 again.

  Next, operation | movement of the control unit 40 in the air conditioner 10 is demonstrated using FIG. The flowchart shown in FIG. 6 shows the refrigerant leakage detection process executed by the control unit 40. This refrigerant leakage detection process is executed when the operation for air conditioning of the room R (the air blowing operation, the cooling operation, the dehumidifying operation, and the heating operation) is stopped.

  In the first step S101, the control unit 40 measures the oxygen concentration C using the oxygen concentration sensor 33. Specifically, the control unit 40 uses the oxygen concentration sensor 33 to measure the oxygen concentration C in the vicinity of the condensed water receiving portion 36A.

  Next, the control unit 40 compares the measured oxygen concentration C with the set value Cs previously stored in the auxiliary storage unit of the control unit 40, and determines whether the oxygen concentration C is equal to or less than the set value Cs. Is determined (step S102).

  The set value Cs is set to 18.7%, for example. This is a value calculated from the lower combustion limit value of R32 being 14.4 vol%. Specifically, when 14.4 vol% of R32 is mixed in the air, the ratio of the air in the mixed gas (air mixed with the refrigerant) is 85.6% (= 100% -14.4%). The oxygen concentration is 17.93% (= 85.6% × 0.209476). That is, when the oxygen concentration is 17.93% or less, the lower limit of combustion of R32 is 14.4 vol% or more, and R32 may be burned. 18.7% set as the set value Cs is an oxygen concentration that is slightly larger than the oxygen concentration of 17.93%.

  If it is determined in step S102 that the oxygen concentration C is greater than the set value Cs (step S102: No), the process returns to step S101. The measurement is again performed using the oxygen concentration sensor 33. On the other hand, when it is determined that the oxygen concentration C is equal to or lower than the set value Cs (step S102: Yes), it is assumed that the refrigerant has leaked, and the process proceeds to the next step S103.

  In step S103, the control unit 40 causes the abnormality display lamp 39 to blink.

  Next, the control unit 40 rotates the blower fan of the blower 32. Thereby, ventilation operation is started. At this time, the control unit 40 adjusts the wind direction plate 37 so that the wind direction of the blown air is in the horizontal direction.

  Next, the control unit 40 measures the absolute humidity H in the room R using the absolute humidity sensor 34 (step S105). At this time, since the air blowing operation has already been performed, the air in the room R is taken in from the opening 35c of the housing 35, and thus the absolute humidity sensor 34 can accurately measure the absolute humidity H in the room R.

Next, the control unit 40 compares the measured absolute humidity H with the set value Hs previously stored in the auxiliary storage unit of the control unit 40, and determines whether or not the absolute humidity H is equal to or higher than the set value Hs. Is determined (step S106). The set value Hs is set to 10.0 g / m ³ , for example.

  If it is determined in step S106 that the absolute humidity H is smaller than the set value Hs (step S106: No), even if the refrigerant burns, the combustion scale is sufficiently small, and the safety of the user is improved. Assuming that it can be secured, the process returns to step S105. The measurement is again performed using the absolute humidity sensor 34. On the other hand, when it is determined that the absolute humidity H is equal to or higher than the set value Hs (step S106: Yes), the process proceeds to the next step S107.

  In step S107, it is determined whether or not the current operation of the air conditioner 10 is a dehumidifying operation. When it is determined that the current operation of the air conditioner 10 is the dehumidifying operation (step S107: Yes), the process proceeds to step S109. On the other hand, when it is determined that the current operation of the air conditioner 10 is not the dehumidifying operation (step S107: No), the process proceeds to the next step S108.

  In step S108, the four-way valve 22 is switched to operate the refrigeration cycle in the cooling operation cycle. Then, cool air is supplied to the room R. Thereby, the dehumidifying operation is started. By this dehumidifying operation, the absolute humidity H in the room R decreases. Further, the wind direction in the dehumidifying operation is maintained in the horizontal direction.

  Next, the control unit 40 measures the discharge temperature T from the compressor 21 using the discharge temperature sensor 25 (step S109).

  Next, the control unit 40 compares the measured discharge temperature T with the set value Ts previously stored in the auxiliary storage unit of the control unit 40, and determines whether or not the discharge temperature T is equal to or higher than the set value Ts. Is discriminated (step S110). The set value Ts is set to 120 ° C., for example. When it is determined that the discharge temperature T is lower than the set value Ts (step S110: No), the process returns to step S105. The measurement is again performed using the absolute humidity sensor 34. On the other hand, when it is determined that the discharge temperature T is equal to or higher than the set value Ts (step S110: Yes), the process proceeds to the next step S111.

  In step S111, the operation of the compressor 21 is stopped and the operation of the entire refrigeration cycle is stopped. As a result, the dehumidifying operation is stopped. However, since the blower fan of the blower 32 continues to rotate, the blower operation is started (step S111).

  Next, the control unit 40 waits for an operation for stopping the air blowing operation from the user (step S112). This stop operation is an operation performed by the user who notices the leakage of the refrigerant by, for example, blinking of the abnormality display lamp 39. The stop operation is performed, for example, via a remote controller. The air blowing operation started in step S111 is continued until this stop operation is performed.

  In step S112, when there is no operation for stopping the air blowing operation (step S112: No), the operation for stopping the air blowing operation from the user is again waited for in step S112. On the other hand, if there is an operation for stopping the air blowing operation (step S112: Yes), the process proceeds to the next step S113.

  In step S113, the rotation of the blower fan of the blower 32 is stopped. Thereby, the air blowing operation is stopped, and the control unit 40 ends the process. Note that the blinking of the abnormality display lamp 39 is continued even after the user performs an operation to stop the blowing operation. The blinking of the abnormality display lamp 39 is stopped after the leakage of the refrigerant is repaired, for example. For example, it is stopped by a professional engineer who maintains the air conditioner 10.

  As described above, according to the air conditioner 10 according to the present embodiment, when the refrigerant leaks, the air conditioner 10 performs the dehumidifying operation until the absolute humidity H in the room R becomes the set value Hs or less. I do. For this reason, moisture in the air in the room R is removed, and the absolute humidity H in the room R decreases. As shown in FIG. 4 described above, the absolute humidity of the alternative refrigerant decreases, so that the combustion scale when the refrigerant ignites becomes small. Thereby, the combustibility of a refrigerant | coolant can be weakened and safety can be improved as a result.

  The air conditioner 10 performs a dehumidifying operation when the refrigerant leaks. Due to the operation of the refrigeration cycle associated with the dehumidifying operation, the refrigerant passing through the indoor heat exchanger 31 has a low pressure, so that leakage of the refrigerant can be suppressed more than during the blowing operation.

  In addition, when the refrigerant leaks, the air conditioner 10 performs the air blowing operation regardless of whether the absolute humidity H in the room R is equal to or less than the set value Hs. For this reason, a refrigerant | coolant can be diffused in the room R and the refrigerant | coolant density | concentration of the whole room R inside can be made low. Thereby, even if there is an ignition source in the room R, the refrigerant can be prevented from burning, and as a result, safety can be improved.

  In the present embodiment, the measurement of the absolute humidity H in the room R by the absolute humidity sensor 34 is performed after the air blowing operation. For this reason, the absolute humidity H in the room R can be accurately measured.

  In the present embodiment, the discharge temperature sensor 25 measures the discharge temperature T of the refrigerant sent from the compressor 21 and stops the operation of the refrigeration cycle based on the discharge temperature T. Thereby, it is possible to prevent the refrigeration cycle from operating in a state where the amount of refrigerant remaining in the refrigeration cycle circuit 100 is small. In addition, it is possible to prevent the compressor 21 from sucking the air in the room R by operating the refrigeration cycle in a state where the amount of remaining refrigerant is small.

  Moreover, in this Embodiment, when a refrigerant | coolant leaks, the air conditioner 10 supplies air to a horizontal direction. Thereby, it becomes easy for the refrigerant to diffuse throughout the room R, and the refrigerant concentration in the whole room R can be further reduced. However, the air supply direction is not limited to the horizontal direction, but may be any direction in which the refrigerant is easily diffused throughout the room R. For example, the direction may be higher than the horizontal direction.

  Further, in the present embodiment, the oxygen concentration sensor 33 is disposed in the vicinity of the condensed water receiving portion 36A where the refrigerant leaked from the refrigeration cycle circuit 100 is likely to accumulate. For this reason, the leakage of the refrigerant can be detected with high accuracy.

  In the present embodiment, the oxygen concentration sensor 33 is used for detecting the leakage of the refrigerant. Since the oxygen concentration sensor 33 is relatively inexpensive as a detection means used for detecting leakage of the refrigerant, the manufacturing cost of the air conditioner 10 can be suppressed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited by the said embodiment.

  For example, in the air conditioner 10 according to the present embodiment, when the refrigerant leaks, the air conditioner 10 performs a dehumidifying operation. However, the present invention is not limited to this, and other operations (for example, cooling operation) may be used as long as the operation is to reduce the absolute humidity H in the room R.

  In this embodiment, R32 is used as an HFC refrigerant having low GWP but flammability. However, an HFO refrigerant (HFC) such as HFO-1234yf, which is a halogenated hydrocarbon having a carbon double bond in its composition. In the case of using this HFO refrigerant as the refrigerant circulating in the refrigeration cycle circuit, the relationship between the absolute humidity and the combustion scale has a tendency similar to that of R32 and the density is higher than that of air as in R32. Alternatively, even when a mixed refrigerant of R32 and HFO refrigerant is used, the same effects as when R32 is used can be obtained by applying the present invention.

  When a refrigerant other than R32 used in the present embodiment is used, it is necessary to change the set value Cs stored in the auxiliary storage unit of the control unit 40 based on the lower combustion limit value of each refrigerant. is there. For example, in the case of HFO-1234yf, the lower limit value of combustion is 6.2 vol%. For this reason, when HFO-1234yf is used, the set value Cs is set to 19.7% (≈ (100% −6.2%) × 0.209476), for example.

  Further, the inventor repeated analysis on alternative refrigerants other than R32 used in the above embodiment (for example, HFO-1234yf, HFO-1234ze), and has the same relationship as the correlation shown in FIG. I have found that. However, since the combustion scale with respect to the absolute humidity H differs for each alternative refrigerant, it is necessary to set the absolute humidity set value Hs for each alternative refrigerant.

  In the present embodiment, the absolute humidity sensor 34 is used to measure the absolute humidity H in the room R. However, the present invention is not limited to this, and a relative humidity sensor and a room temperature sensor may be used. In this case, the absolute humidity H in the room R can be calculated based on the relative humidity measured by the relative humidity sensor and the room temperature measured by the room temperature sensor. Since the relative humidity sensor is less expensive than the absolute humidity sensor, the manufacturing cost of the air conditioner 10 can be suppressed.

  In the present embodiment, the oxygen concentration sensor 33 is disposed in the vicinity of the condensed water receiving portion 36A where the refrigerant leaked from the refrigeration cycle circuit is likely to accumulate. However, the present invention is not limited thereto, and may be disposed on the air path 38 as shown in FIG. Since the refrigerant overflowing from the condensed water receiving portion 36A passes through the air passage 38, the oxygen concentration C can be accurately measured.

In the present embodiment, the control unit 40 determines whether or not the discharge temperature T measured by the discharge temperature sensor 25 is equal to or higher than the set value Ts. The operation of is stopped. Thereby, the circulation of the refrigerant in the refrigeration cycle circuit 100 is stopped. However, the present invention is not limited to this, and when the absolute humidity setting value Hs2 lower than the absolute humidity H setting value Hs is set in advance and the absolute humidity H becomes equal to or lower than the setting value Hs2, the refrigerant of the refrigeration cycle circuit 100 is obtained. The circulation may be stopped. The set value Hs2 is, for example, 5.0 g / m ³ .

  In the present embodiment, an abnormality display lamp is used as means for notifying that the refrigerant has leaked. However, the present invention is not limited to this, and the refrigerant leakage may be notified by a warning sound or the like.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention and do not limit the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Air conditioner 11 Connection pipe 12 Flare nut 13 Stop valve 20 Outdoor unit 20a, 20b, 20c Flow path 21 Compressor 22 Four-way valve 23 Outdoor heat exchanger 24 Expansion valve 25 Discharge temperature sensor (discharge temperature measurement means)
DESCRIPTION OF SYMBOLS 30 Indoor unit 30a Flow path 31 Indoor heat exchanger 31a Pipe 32 Blower 33 Oxygen concentration sensor 34 Absolute humidity sensor (humidity measurement means)
35 Housing 35a Air outlet 35b Suction port 35c Opening 36A, 36B Condensate receiving part 37 Wind direction plate 38 Air path 39 Abnormal indication lamp (notification means)
40 Control unit (control unit)
50 Room temperature sensor 100 Refrigeration cycle circuit R Indoor C Oxygen concentration Cs Set value (Set oxygen concentration)
H Absolute humidity Hs Set value (first set absolute humidity)
Hs2 set value (second set absolute humidity)
T Discharge temperature Ts Set value (Set discharge temperature)

Claims (13)

A refrigeration cycle circuit comprising: a flow path through which a refrigerant composed of combustible HFC circulates; and a heat exchanger connected to the flow path and performing heat exchange with air by evaporating or condensing the refrigerant.
A blower for supplying the air heat-exchanged by the heat exchanger into an air-conditioned room;
Detecting means for detecting leakage of the refrigerant from the refrigeration cycle circuit;
When the detection means detects leakage of the refrigerant, the refrigeration cycle circuit and the blower are controlled so as to reduce the absolute humidity in the room by performing an operation of dehumidifying the indoor air to be air conditioned. A control unit,
Having an air conditioner. The blower includes a wind direction control unit that controls the wind direction,
2. The air conditioner according to claim 1, wherein the control unit controls the wind direction control unit so as to blow air in a horizontal direction or a direction upward from the horizontal when the detection unit detects leakage of the refrigerant. The detection means includes
An oxygen concentration sensor for measuring the oxygen concentration;
Oxygen concentration determination means for determining whether the oxygen concentration measured by the oxygen concentration sensor is equal to or lower than a set oxygen concentration;
The air conditioner according to claim 1 or 2, comprising: The heat exchanger includes a condensed water receiving portion that receives condensed water generated by heat exchange with the air,
The air conditioner according to claim 3, wherein the oxygen concentration sensor is disposed in the vicinity of the condensed water receiver. Having an absolute humidity measuring means for measuring the absolute humidity in the room subject to air conditioning;
The air conditioner according to any one of claims 1 to 4, wherein the control unit controls the refrigeration cycle circuit and the blower based on the absolute humidity measured by the absolute humidity measuring unit.   When the detection unit detects leakage of the refrigerant and the absolute humidity measured by the absolute humidity measurement unit is equal to or higher than a first set absolute humidity, the control unit detects the absolute value in the room to be air conditioned. The air conditioner of Claim 5 which controls the said refrigeration cycle circuit and the said air blower so that humidity may be made low.   The control unit stops circulation of the refrigerant in the refrigeration cycle circuit when the absolute humidity measured by the absolute humidity measuring unit becomes equal to or lower than a second set absolute humidity which is lower than the first set absolute humidity. The air conditioner according to claim 6.   The air conditioner according to any one of claims 5 to 7, wherein the absolute humidity measuring unit includes an absolute humidity sensor that measures the absolute humidity in the room. The absolute humidity measuring means includes a relative humidity sensor that measures the relative humidity in the room, and a room temperature sensor that measures the room temperature in the room,
The said control part calculates the absolute humidity in the said room based on the said room temperature which the said room temperature sensor measured, and the said relative humidity which the said relative humidity sensor measured. The air conditioner described.   The air conditioner according to any one of claims 1 to 9, further comprising a notification unit that notifies that the refrigerant has leaked when the detection unit detects leakage of the refrigerant. The refrigeration cycle circuit includes a compressor that is connected to the flow path and compresses the refrigerant, and a discharge temperature measuring unit that measures a discharge temperature of the refrigerant sent from the compressor,
The control unit determines whether or not the discharge temperature measured by the discharge temperature measurement unit is equal to or higher than a set discharge temperature, and stops the operation of the compressor when the discharge temperature is equal to or higher than a set discharge temperature. Item 11. The air conditioner according to any one of Items 1 to 10. An air conditioning method for conditioning air by performing heat exchange by evaporating or condensing while circulating a refrigerant composed of combustible HFC,
A detection step of detecting leakage of the refrigerant from the refrigeration cycle circuit;
When leakage of the refrigerant is detected by the detection step, a dehumidification step of lowering the indoor absolute humidity by performing an operation of dehumidifying the indoor air to be air-conditioned,
Including air conditioning method. On the computer,
A detection process for detecting leakage of refrigerant composed of combustible HFC from the refrigeration cycle circuit;
A control step of controlling the refrigeration cycle circuit so as to lower the absolute humidity in the room by performing an operation of dehumidifying the indoor air to be air conditioned when the refrigerant leakage is detected in the detection step;
A program that executes

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