Refrigeration Cycle Equipment

Abstract

A refrigeration cycle device (100) comprises: a refrigerant circuit (80); and a non-azeotropic refrigerant, which flows through refrigerant pipes (51-56). When the non-azeotropic refrigerant passes through an outdoor heat exchanger (40), a temperature difference occurs between an inlet and an outlet of the outdoor heat exchanger (40). The outdoor heat exchanger (40) comprises: fin groups (L1, L2), which are stacked with spaces therebetween; and heat transfer tubes (R1-R12), which pass through the fin groups (L1, L2) in the stacking direction of the fin groups (L1, L2) and through which the non-azeotropic refrigerant flows. The fin groups (L1, L2) comprise: a first fin portion (A1) to which frost can adhere in a humid environment, and a second fin portion (A2) to which frost does not adhere and for which ventilation is ensured.

Description

[Technical field]

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

[0002] In recent years, there has been a demand for refrigerants with low GWP (global warming potential). However, it is difficult to reduce GWP while maintaining performance at the same time, and the use of mixed refrigerants that combine two or more types of refrigerants is being considered to compensate for the advantages and disadvantages of each refrigerant. It is known that in the case of non-azeotropic mixed refrigerants that combine refrigerants with different boiling points, a slope of the isotherm occurs in the two-phase region on the pH diagram.

[0003] Japanese Patent Laid-Open Publication No. 2018-21721 (Patent Document 1) discloses a refrigeration cycle device that uses a non-azeotropic refrigerant mixture and reduces bias in temperature distribution throughout the evaporator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-21721 A Summary of the Invention [Problem to be solved by the invention]

[0005] For example, during heating operation in low-temperature, high-humidity conditions where the outside air temperature is around 2°C, there is concern that frost may cause a decrease in heating capacity. For this reason, when an air conditioning system is installed, the system is generally designed to have a sufficient margin for the maximum capacity that can be achieved in a frost-free state under low-temperature, high-humidity conditions. When frost occurs, the operating frequency of the compressor is increased to increase the amount of refrigerant circulating, thereby avoiding a decrease in heating capacity due to frost.

[0006] However, when the compressor frequency reaches its maximum and capacity is reduced due to frost formation, defrosting operation is performed. During this time, low-temperature refrigerant flows into the load side, causing the temperature to drop, reducing comfort on the load side. In addition, the total period of one heating operation and the subsequent defrosting time, i.e. the defrosting period, becomes shorter, causing a decrease in the integrated heating capacity and a decrease in the average coefficient of performance (COP). During heating operation at low temperature and high humidity, the evaporation temperature of the refrigerant is lower than the outside air, making frost formation unavoidable, so technology is needed to extend the defrosting period while suppressing frost formation.

[0007] An object of the present disclosure is to provide a refrigeration cycle device that can extend a defrosting period while suppressing frost formation. [Means for solving the problem]

[0008] The present disclosure relates to a refrigeration cycle device. The refrigeration cycle device includes a refrigerant circuit in which a compressor, a condenser, a first expansion valve, and an evaporator are connected by a refrigerant pipe, and a non-azeotropic refrigerant flowing through the refrigerant pipe. When the non-azeotropic refrigerant passes through the evaporator, a temperature difference occurs between the inlet and the outlet of the evaporator. The evaporator includes a group of fins stacked at intervals, and a heat transfer tube that penetrates the group of fins in the stacking direction of the group of fins and through which the non-azeotropic refrigerant flows. The group of fins includes a first fin portion on which frost may adhere in a humid environment, and a second fin portion on which frost does not adhere and ventilation is ensured. Effect of the Invention

[0009] According to the refrigeration cycle device of the present disclosure, frost formation can be suppressed and the defrosting period can be extended during heating operation at low temperature and high humidity, thereby improving comfort on the load side. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing a configuration of a refrigeration cycle device according to a first embodiment. [Diagram 2] FIG. 2 is a pH diagram of a refrigeration cycle device in an example study using an azeotropic refrigerant. [Diagram 3] FIG. 1 is a diagram showing a frosting region of an outdoor heat exchanger in a study example using an azeotropic refrigerant. [Figure 4] FIG. 2 is a ph diagram of the refrigeration cycle device of the present embodiment using a non-azeotropic refrigerant. [Diagram 5] 1 is a diagram showing the configuration of an outdoor heat exchanger according to an embodiment of the present invention that uses a non-azeotropic refrigerant, and a frosting region. [Figure 6] FIG. 6 is a front view of the outdoor heat exchanger shown in FIG. 5. [Figure 7] 10A and 10B are diagrams for explaining the difference in defrosting period between the refrigeration cycle device of the study example and the refrigeration cycle device of the present embodiment. [Figure 8] FIG. 11 is a diagram showing a configuration of a refrigeration cycle device according to a second embodiment. [Figure 9] FIG. 2 is a diagram for explaining the arrangement of a temperature sensor 111. [Figure 10] 11 is a diagram for explaining how to determine the mounting position of a temperature sensor 111. FIG. [Figure 11] 11 is a flowchart for explaining a process executed by a control device in the second embodiment. [Figure 12] FIG. 11 is a ph diagram for explaining the change in the refrigeration cycle in the second embodiment. [Figure 13] FIG. 11 is a diagram showing a configuration of a refrigeration cycle device according to a third embodiment. [Figure 14] 13 is a flowchart illustrating a process executed by a control device in the third embodiment. [Figure 15] FIG. 11 is a ph diagram for explaining the change in the refrigeration cycle in the third embodiment. [Figure 16] FIG. 11 is a diagram showing a configuration of a refrigeration cycle device according to a fourth embodiment. [Figure 17] 13 is a flowchart for explaining a process executed by a control device in the fourth embodiment. [Figure 18] FIG. 11 is a ph diagram for explaining the change in the refrigeration cycle in the fourth embodiment. [Figure 19]FIG. 11 is a diagram showing a configuration of a refrigeration cycle device according to a fifth embodiment. [Figure 20] 13 is a flowchart for explaining a process executed by a control device in the fifth embodiment. [Figure 21] FIG. 13 is a ph diagram for explaining changes in the refrigeration cycle in embodiment 5. [Figure 22] FIG. 13 is a diagram showing a configuration of a refrigeration cycle device according to a sixth embodiment. [Diagram 23] 23 is a flowchart for explaining a process executed by a control device in the sixth embodiment. [Figure 24] FIG. 23 is a ph diagram for explaining the change in the refrigeration cycle in the sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Several embodiments will be described below, but it is planned from the beginning of the application that the configurations described in each embodiment will be appropriately combined. Note that the same or corresponding parts in the drawings are given the same reference numerals and their description will not be repeated. Note that the size relationship of each component in the following drawings may differ from the actual one.

[0012] Embodiment 1 Fig. 1 is a diagram showing the configuration of a refrigeration cycle apparatus according to embodiment 1. The refrigeration cycle apparatus 100 includes a refrigerant circuit 80 including a compressor 10, an indoor heat exchanger 20, an expansion valve LEV1, an outdoor heat exchanger 40, pipes 51-56, and a four-way valve 50. The four-way valve 50 has ports P1-P4.

[0013] The pipe 51 is connected between the discharge port of the compressor 10 and the port P1 of the four-way valve 50. The pipe 52 is connected between the port P3 of the four-way valve 50 and the port P1 of the indoor heat exchanger 20. The pipe 53 is connected between the indoor heat exchanger 20 and the expansion valve LEV1. The pipe 54 is connected between LEV1 and the outdoor heat exchanger 40.

[0014] The pipe 55 is connected between the port P2 of the outdoor heat exchanger 40 and the port P4 of the four-way valve 50. The pipe 56 is connected between the suction port of the compressor 10 and the port P2 of the four-way valve 50.

[0015] The compressor 10 is configured to change its operating frequency according to a control signal received from a control device (not shown). Specifically, the compressor 10 has a built-in drive motor whose rotation speed is variable and controlled by an inverter, and when the operating frequency is changed, the rotation speed of the drive motor changes. The output of the compressor 10 is adjusted by changing the operating frequency of the compressor 10. Various types of compressors 10 can be used, such as a rotary type, a reciprocating type, a scroll type, a screw type, etc.

[0016] The four-way valve 50 is controlled to be in either a cooling operation state or a heating operation state by a control signal received from a control device (not shown). In the heating operation state, as shown by the solid line, the port P1 communicates with the port P3, and the port P2 communicates with the port P4. In the cooling operation state, as shown by the dashed line, the port P1 communicates with the port P4, and the port P2 communicates with the port P3.

[0017] By operating the compressor 10 in a heating operation state, the refrigerant circulates in the refrigerant circuit in the following order: compressor 10, indoor heat exchanger 20, LEV1, outdoor heat exchanger 40, and compressor 10. By operating the compressor 10 in a cooling operation state, the refrigerant circulates in the refrigerant circuit in the following order: compressor 10, outdoor heat exchanger 40, LEV1, indoor heat exchanger 20, and compressor 10.

[0018] Fig. 2 is a pH diagram of a refrigeration cycle device in an example in which an azeotropic refrigerant is used, and Fig. 3 is a diagram showing a frosting region of an outdoor heat exchanger in an example in which an azeotropic refrigerant is used.

[0019] As shown in Fig. 2, when an azeotropic refrigerant is used, there is no temperature rise in the two-phase region, so frost forms uniformly on the front surface of the outdoor heat exchanger 40 that comes into contact with the intake air during heating operation at low temperature and high humidity. In such a case, the air passage is narrowed due to the frost, and the volume of air blown out from the outdoor heat exchanger 40 is reduced. Therefore, defrosting must be performed frequently before the air passage is blocked, and the defrosting cycle is short.

[0020] Fig. 4 is a ph diagram of the refrigeration cycle device of this embodiment using a non-azeotropic refrigerant. Fig. 5 is a diagram showing the configuration and frosting region of the outdoor heat exchanger of this embodiment using a non-azeotropic refrigerant. Fig. 6 is a front view of the outdoor heat exchanger shown in Fig. 5.

[0021] As shown in the ph diagram of Fig. 4, when a non-azeotropic refrigerant is used, there is a slope in the isotherm in the two-phase region, so that even if the temperature of the refrigerant inlet of the outdoor heat exchanger 40 is -5°C during heating operation, the temperature of the refrigerant outlet can be 0.5°C. This means that the temperature of a part of the outdoor heat exchanger 40 can be made 0°C or higher. In this embodiment, the refrigeration cycle device is operated so as to obtain the temperature distribution shown in Fig. 4 during heating operation at low temperature and high humidity when the outside air temperature is around 2°C.

[0022] As shown in Fig. 5, the refrigerant flows into the outdoor heat exchanger 40 from the pipe 54, and flows out from the outdoor heat exchanger 40 to the pipe 55. If the side that draws in air is the front side, the outdoor heat exchanger 40 has a first row of fin group L1 arranged on the front side and a second row of fin group L2 arranged on the back side. In both of the fin groups L1 and L2, pipes that serve as refrigerant passages in units of six are arranged in parallel and are connected to the side surfaces. These six pipes will be referred to as heat transfer tubes R1 to R6 from the top in the fin group L1, and as heat transfer tubes R7 to R12 from the bottom in the fin group L2.

[0023] As shown in Figures 5 and 6, the refrigerant flows in from the right side of the uppermost heat transfer tube R1 of the first row of fin group L1, flows from right to left through heat transfer tube R1, passes through connecting pipe C12, and flows from left to right through heat transfer tube R2, making one round trip.

[0024] The refrigerant that has flowed out of heat transfer tube R2 flows through heat transfer tube R3 from right to left via connecting pipe C23, and then flows through heat transfer tube R4 from left to right via connecting pipe C34, making another round trip.

[0025] The refrigerant that has flowed out of heat transfer tube R4 flows from right to left through heat transfer tube R5 via connecting pipe C45, and then flows from left to right through heat transfer tube R6 via connecting pipe C56, making another round trip.

[0026] Similarly, the refrigerant makes three round trips in the left-right direction of Fig. 6 for the heat transfer tubes R7 to R12 shown in Fig. 5. However, the heat transfer tubes R7 to R12 are different from the heat transfer tubes R1 to R6 in that the refrigerant flows from the lower row to the upper row.

[0027] That is, the refrigerant flowing out from heat transfer tube R6 passes through connecting pipe C67 and flows through heat transfer tube R7 from right to left in Fig. 6. Then, via the connecting pipe, the refrigerant flows through heat transfer tube R8 from left to right, making another round trip.

[0028] The refrigerant flowing out of heat transfer tube R8 passes through connecting pipe C89 and flows through heat transfer tube R9 from right to left in Fig. 6. Then, via the connecting pipe, it flows through heat transfer tube R10 from left to right, making another round trip.

[0029] The refrigerant flowing out of heat transfer tube R10 flows through heat transfer tube R11 from right to left in FIG. 6 via connecting pipe C1011. Then, through the connecting pipe, the refrigerant flows from left to right through heat transfer tube R12, makes one more round trip, and is sent to pipe 55.

[0030] When a non-azeotropic refrigerant is applied to the outdoor heat exchanger 40 configured as described above, during heating operation in a low-temperature, high-humidity environment where the outdoor air temperature is around 2°C, the area can be divided into a frosting area A1 where frost may form and a non-frosting area A2 where frost does not form. Therefore, even if the volume of blown air is reduced in the frosting area A1, the volume of blown air can be ensured in the non-frosting area A2. In this way, uneven frosting on the outdoor heat exchanger 40 can extend the defrosting cycle.

[0031] Fig. 7 is a diagram for explaining the difference in defrosting period between the refrigeration cycle device of the study example and the refrigeration cycle device of this embodiment. Fig. 7 shows the capacity J0, compressor frequency F0, and frost amount G0 of the refrigeration cycle device of the comparative example shown in Fig. 2 and Fig. 3, and the capacity J1, compressor frequency F1, and frost amount G1 of the refrigeration cycle device of this embodiment shown in Fig. 4 to Fig. 6.

[0032] When frost forms on the entire surface as in the comparative example, the amount of frost G0>G1 from time t0 to t1. Accordingly, in order to ensure the required capacity, the compressor frequency F0 reaches the maximum frequency (upper limit frequency) at time t1. Therefore, as the amount of frost G0 increases from time t1 to t3, the capacity J0 decreases early, and at time t3, defrosting becomes necessary and starts.

[0033] In contrast, in this embodiment, the amount of frost G1 is less than the amount of frost G0, and the compressor frequency F1 reaches its upper limit at time t2, which is later than time t1. Therefore, the capacity J1 decreases to a value at which defrosting needs to be started at time t4, which is later than time t3. Since the defrosting time thereafter is substantially constant in both the comparative example and this embodiment, the defrosting cycle is longer in this embodiment, which has a longer heating operation time, than in the comparative example. Therefore, in the refrigeration cycle device of this embodiment, the comfort on the load side is improved by extending the defrosting cycle, and the average COP is improved.

[0034] Embodiment 2 Fig. 8 is a diagram showing a configuration of a refrigeration cycle apparatus according to embodiment 2. A refrigeration cycle apparatus 110 shown in Fig. 8 further includes a control device 90 and a temperature sensor 111 in addition to the configuration of the refrigeration cycle apparatus 100 in Fig. 1. The other configuration has been described in Fig. 1, and therefore description thereof will not be repeated here.

[0035] The control device 90 includes a CPU (Central Processing Unit) 91, a memory 92 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input / output buffer (not shown), etc. The CPU 91 deploys a program stored in the ROM into the RAM, etc., and executes it. The programs stored in the ROM are programs in which the processing procedures of the control device 90 are written. The control device 90 controls each device in the refrigeration cycle device 110 in accordance with these programs. This control is not limited to processing by software, and can also be processed by dedicated hardware (electronic circuits). In particular, the control device 90 is configured to control the LEV1 according to the output of the temperature sensor 111.

[0036] Fig. 9 is a diagram for explaining the arrangement of temperature sensor 111. Fig. 9 shows the arrangement of temperature sensor 111 in outdoor heat exchanger 40 shown in Fig. 5. Outdoor heat exchanger 40 has been described with reference to Figs. 4 to 6, and therefore description thereof will not be repeated here.

[0037] The temperature sensor 111 is disposed at the boundary between a portion of the outdoor heat exchanger 40 that is to be the frost region A1 and a portion that is to be the non-frost region A2. If the refrigeration cycle device is controlled so that the temperature detected by the temperature sensor 111 becomes 0°C, frost will form in the frost region A1 and not in the non-frost region A2 during heating operation at low temperature and high humidity, so that ventilation in the non-frost region A2 can be ensured and the defrosting cycle can be appropriately extended. The boundary between the frost region A1 and the non-frost region A2 can be experimentally determined in advance so as to be appropriate for performing low-load heating at low temperature and low humidity.

[0038] Fig. 10 is a diagram for explaining the determination of the installation position of the temperature sensor 111. As shown by the solid line in Fig. 10, the relationship between the frost area and the capacity at the maximum frequency under low-temperature and high-humidity operating conditions is obtained in advance. The installation position of the temperature sensor 111 is determined so that the area of ​​the frost region A1 becomes the frost area S(A1) at which the required capacity during low-temperature and high-humidity operation is exhibited.

[0039] FIG. 11 is a flowchart for explaining the processing executed by the control device in Embodiment 2. The control device 90 determines whether the temperature Tsen detected by the temperature sensor 111 attached to the outdoor heat exchanger 40 is lower than the frosting temperature Tfro (step S1). The frosting temperature Tfro can be, for example, 0°C.

[0040] While Tsen < Tfro does not hold (NO in S1), the control device 90 repeats the processing of step S1. When Tsen < Tfro holds (YES in S1), the control device 90 increases the opening degree of LEV1 so that Tsen ≥ Tfro (S2).

[0041] FIG. 12 is a p-h diagram for explaining the change in the refrigeration cycle in Embodiment 2. In step S2, when the opening degree of LEV1 is increased, the degree of subcooling at the outlet of the load side heat exchanger decreases, and the refrigeration cycle changes from the state shown by the solid line CY1 to the state shown by the broken line CY2 on the p-h diagram.

[0042] Until the compressor frequency F reaches the maximum value Fmax at this time (NO in S3), the control device 90 adjusts the compressor frequency F (S5) so that the heating capacity Q becomes the target heating capacity Qtar, and executes the processing from step S1 again.

[0043] On the other hand, when the compressor frequency F reaches the maximum value Fmax (YES in S3), since the target capacity is not reached, the control device 90 performs a defrost determination. The necessity of defrosting can be determined based on the continuous operation time of heating, the allowable capacity reduction rate during heating (low-pressure refrigerant pressure drop), etc.

[0044] When defrosting is not required (NO in S4), the control device 90 executes the processing from step S1 again. When defrosting is necessary (YES in S4), the control device 90 starts the defrost operation.

[0045] As described above, in the heating operation with low temperature and high humidity, the refrigeration cycle device of Embodiment 2 increases the enthalpy at the refrigerant inlet of the outdoor heat exchanger 40 and raises the temperature by utilizing the temperature gradient of the zeotropic refrigerant. Thereby, frosting occurs only in a part of the region of the outdoor heat exchanger 40, and the defrosting cycle is extended. In particular, since the temperature sensor 111 is arranged at the boundary between the frosted region and the non-frosted region of the outdoor heat exchanger 40, the frosted region can be accurately controlled.

[0046] Embodiment 3. FIG. 13 is a diagram showing the configuration of the refrigeration cycle device according to Embodiment 3. In the refrigeration cycle device 120 shown in FIG. 13, in addition to the configuration of the refrigeration cycle device 110 in FIG. 8, the refrigerant circuit 80 further includes an internal heat exchanger 121 and an expansion valve LEV2. A part of the refrigerant flowing through the pipe 53 is branched into the bypass flow path 61, decompressed by the expansion valve LEV2, and returned to the compressor 10. In FIG. 13, the refrigerant is returned to the intermediate pressure port of the compressor 10, but the bypass flow path may be configured to return to the suction port of the compressor 10. The internal heat exchanger 121 is configured to perform heat exchange between the refrigerant flowing out of the indoor heat exchanger 20 and the refrigerant after being decompressed by the expansion valve LEV2 in the bypass flow path 61. Since other configurations are described in FIG. 8, the description is not repeated here.

[0047] FIG. 14 is a flowchart for explaining the process executed by the control device in Embodiment 3. The process of the flowchart in FIG. 14 includes step S12 instead of step S2 in the process of the flowchart shown in FIG. 11. Since the processing of other parts is described in FIG. 11, step S12 will be described here.

[0048] In the process of FIG. 11, the opening degree of LEV1 was increased so that Tsen ≥ Tfro detected by the temperature sensor 111 (S2). However, in the process of FIG. 14, when Tsen < Tfro (YES in S1), the opening degree of LEV2 is decreased so that Tsen ≥ Tfro (S12).

[0049] 15 is a ph diagram for explaining the change in the refrigeration cycle in the embodiment 3. In step S12, when the opening degree of LEV2 is reduced, the degree of subcooling at the outlet of the internal heat exchanger 121 decreases, and the refrigeration cycle changes from the state shown by the solid line CY11 to the state shown by the dashed line CY12 on the ph diagram.

[0050] In this way, in embodiment 3, by changing the opening degree of LEV2, the area where temperature sensor 111 is located is kept near 0°C, and the boundary between frosted area A1 and non-frosted area A2 is maintained as intended.

[0051] Then, when the compressor frequency F reaches a maximum value Fmax during operation and does not reach the target capacity, a defrosting decision is made (S4) and a defrosting operation is started.

[0052] By adopting the configuration and control as in the third embodiment, it is also possible to cause frost to form only in a partial area of ​​the outdoor heat exchanger 40, thereby extending the defrosting cycle.

[0053] Embodiment 4 Fig. 16 is a diagram showing a configuration of a refrigeration cycle apparatus according to a fourth embodiment. In a refrigeration cycle apparatus 130 shown in Fig. 16, in addition to the configuration of the refrigeration cycle apparatus 110 in Fig. 8, a refrigerant circuit 80 further includes a bypass flow path 62 and an expansion valve LEV3. A part of the discharge gas refrigerant flowing through the pipe 51 is branched to the bypass flow path 62 at a branch point BP2, the flow rate is adjusted by the expansion valve LEV3, and the refrigerant merges with the refrigerant in the pipe 54 at a merge point MP2. The other configuration has been described with reference to Fig. 8, and therefore description thereof will not be repeated here.

[0054] Fig. 17 is a flowchart for explaining the processing executed by the control device in the embodiment 4. The processing in the flowchart in Fig. 17 includes step S22 instead of step S2 in the processing in the flowchart shown in Fig. 11. Other parts of the processing are explained in Fig. 11, so step S22 will be explained here.

[0055] In the process of FIG. 11, the opening degree of LEV1 was increased so that Tsen ≧ Tfro detected by the temperature sensor 111 (S2). However, in the process of FIG. 17, when Tsen < Tfro (YES in S1), the opening degree of LEV3 is increased so that Tsen ≧ Tfro (S22).

[0056] FIG. 18 is a p-h diagram for explaining the change of the refrigeration cycle in the fourth embodiment. In step S22, when the opening degree of LEV3 is increased, the refrigerant in the bypass flow path 62 that joins the two-phase refrigerant flowing into the outdoor heat exchanger 40 increases, and the temperature of the inlet portion of the outdoor heat exchanger 40 rises. In the refrigeration cycle, as shown by the arrows CY21 and CY22 in the p-h diagram shown in FIG. 18, when a part of the discharged gas joins the refrigerant, the specific enthalpy of the refrigerant at the inlet portion of the outdoor heat exchanger 40 also increases.

[0057] In this way, in the fourth embodiment, by changing the opening degree of LEV3, the portion where the temperature sensor 111 is disposed is kept near 0°C, and the boundary between the frosting region A1 and the non-frosting region A2 is kept as intended.

[0058] Then, when the compressor frequency F reaches the maximum value Fmax during operation and the target capacity cannot be reached, the defrost operation is started after passing through the defrost determination (S4).

[0059] With the configuration and control as in the fourth embodiment, frosting can be caused only in a partial region of the outdoor heat exchanger 40, and the defrost cycle can be extended.

[0060] Embodiment 5. FIG. 19 is a diagram showing the configuration of a refrigeration cycle apparatus according to the fifth embodiment. In the refrigeration cycle apparatus 140 shown in FIG. 19, in addition to the configuration of the refrigeration cycle apparatus 110 of FIG. 8, the refrigerant circuit 80 further includes a heater 141. The heater 141 can heat the refrigerant flowing through the pipe 54. Since the other configurations have been described in FIG. 8, the description will not be repeated here.

[0061] FIG. 20 is a flowchart for explaining the processing executed by the control device in Embodiment 5. The processing of the flowchart in FIG. 20 includes step S32 instead of step S2 in the processing of the flowchart shown in FIG. 11. Since the processing of other parts is described in FIG. 11, step S32 will be described here.

[0062] In the processing of FIG. 11, the opening degree of LEV1 was increased so that Tsen ≧ Tfro detected by the temperature sensor 111 (S2), but in the processing of FIG. 20, when Tsen < Tfro (YES in S1), the heating amount of the heater 141 is increased so that Tsen ≧ Tfro (S32).

[0063] FIG. 21 is a p-h diagram for explaining the change in the refrigeration cycle in Embodiment 5. In step S32, when the heating amount of the heater 141 is increased, the temperature of the refrigerant flowing into the outdoor heat exchanger 40 rises, and the temperature of the inlet portion of the outdoor heat exchanger 40 rises. The refrigeration cycle changes as shown from CY31 to CY32 on the p-h diagram shown in FIG. 21, and the specific enthalpy of the refrigerant at the inlet portion of the outdoor heat exchanger 40 also increases as shown by the arrow in the figure.

[0064] In this way, in Embodiment 5, by changing the heating amount of the heater 141, the portion where the temperature sensor 111 is disposed is kept near 0°C, and the boundary between the frosting region A1 and the non-frosting region A2 is kept as intended.

[0065] Then, when the compressor frequency F reaches the maximum value Fmax during operation and the target capacity cannot be reached, the defrosting operation is started after passing the defrosting determination (S4).

[0066] With the configuration and control as in Embodiment 5, frosting can be caused only in a partial region of the outdoor heat exchanger 40, and the defrosting cycle can be extended.

[0067] Embodiment 6. FIG. 22 is a diagram showing the configuration of the refrigeration cycle apparatus according to Embodiment 6. In the refrigeration cycle apparatus 150 shown in FIG. 22, in addition to the configuration of the refrigeration cycle apparatus 110 in FIG. 8, the refrigerant circuit 80 further includes a three-way valve 152 and an internal heat exchanger 151. The three-way valve 152 is provided in the middle of the pipe 51, and is a flow path switching device that switches whether to directly send the refrigerant discharged from the compressor 10 to the port P1 of the four-way valve or to send it via the internal heat exchanger 151 according to a control signal from the control device 90. The internal heat exchanger 151 is configured to perform heat exchange between the refrigerant flowing through the pipe 54 and the refrigerant sent from the compressor 10 via the three-way valve 152. Since the other configurations have been described in FIG. 8, the description will not be repeated here.

[0068] FIG. 23 is a flowchart for explaining the processing executed by the control device in Embodiment 6. The processing of the flowchart in FIG. 23 includes step S42 instead of step S2 in the processing of the flowchart shown in FIG. 11. Since the processing of the other parts has been described in FIG. 11, step S42 will be described here.

[0069] In the processing of FIG. 11, the opening degree of LEV1 was increased so that Tsen≧Tfro detected by the temperature sensor 111 (S2), but in the processing of FIG. 20, when Tsen<Tfro (YES in S1), the three-way valve 152 is switched so that the refrigerant discharged from the compressor 10 flows through the internal heat exchanger 151 (S42). As a result, the state of the refrigerant circuit 80 becomes a state where Tsen≧Tfro, or approaches such a state.

[0070] Fig. 24 is a ph diagram for explaining the change in the refrigeration cycle in the sixth embodiment. When the three-way valve 152 is switched in step S42 so that the discharged refrigerant is introduced into the internal heat exchanger 151, the refrigeration cycle changes from CY41 to CY42 on the ph diagram shown in Fig. 24. That is, as shown in CY42, the refrigerant discharged from the compressor 10 releases heat as shown by the arrow CY42A before flowing into the indoor heat exchanger 20. The refrigerant that has passed through LEV1 receives this heat as shown by the arrow CY42B, and the temperature of the refrigerant flowing into the outdoor heat exchanger 40 increases.

[0071] In this way, in embodiment 6, by changing the destination of the discharged refrigerant so that it passes through internal heat exchanger 151, the area where temperature sensor 111 is located is kept near 0°C, and the boundary between frosted area A1 and non-frosted area A2 is maintained as intended.

[0072] Then, when the compressor frequency F reaches a maximum value Fmax during operation and does not reach the target capacity, a defrosting decision is made (S4) and a defrosting operation is started.

[0073] By adopting the configuration and control as in the sixth embodiment, it is also possible to cause frost to form only in a partial area of ​​the outdoor heat exchanger 40, thereby extending the defrosting cycle.

[0074] (summary) The above-described embodiment will be summarized again with reference to the drawings.

[0075] The present disclosure relates to a refrigeration cycle device 100. The refrigeration cycle device 100 shown in Fig. 1 includes a refrigerant circuit 80 in which a compressor 10, an indoor heat exchanger 20 (condenser), a first expansion valve LEV1, and an outdoor heat exchanger 40 (evaporator) are connected by refrigerant pipes 51-56, and a non-azeotropic refrigerant flowing through the refrigerant pipes 51-56. When the non-azeotropic refrigerant passes through the outdoor heat exchanger 40 (evaporator), a temperature difference occurs between the inlet and the outlet of the outdoor heat exchanger 40 (evaporator). As shown in Figs. 5 and 6, the outdoor heat exchanger 40 (evaporator) includes fin groups L1, L2 stacked at intervals, and heat transfer tubes R1-R12 that penetrate the fin groups L1, L2 in the stacking direction of the fin groups L1, L2 and through which the non-azeotropic refrigerant flows. Fin groups L1, L2 include a first fin portion (frosted region A1) on which frost may form in a humid environment, and a second fin portion (non-frosted region A2) on which no frost forms and ventilation is ensured.

[0076] Preferably, the refrigeration cycle apparatus 100 further includes a control device 90 that controls the refrigerant circuit 80. As described in Fig. 4 and Fig. 5, the control device 90 controls the refrigerant circuit 80 so that the temperature of the non-azeotropic refrigerant flowing through the portion of the heat transfer tube that penetrates the first fin portion (heat transfer tubes R1 to R3) is 0°C or lower, and the temperature of the non-azeotropic refrigerant flowing through the heat transfer tubes of the second fin portion (heat transfer tubes R4 to R12) is 0°C or higher.

[0077] Preferably, as shown in Fig. 8 and Fig. 9, the first fin portion is arranged in a predetermined frosting region A1 in the outdoor heat exchanger 40 (evaporator). The second fin portion is arranged in a predetermined non-frosting region A2 in the outdoor heat exchanger 40 (evaporator). The refrigeration cycle device 110 further includes a temperature sensor 111 arranged at the boundary between the frosting region A1 and the non-frosting region A2 in the outdoor heat exchanger 40 (evaporator). The control device 90 is configured to control the opening degree of the first expansion valve LEV1 based on the output of the temperature sensor 111 so that the temperature of the boundary between the frosting region A1 and the non-frosting region A2 becomes 0°C.

[0078] Preferably, in the refrigeration cycle device 120 shown in FIG. 13, the refrigerant circuit 80 further includes a bypass flow path 61 that branches off at a branch point BP1 from the refrigerant piping 53 connecting the indoor heat exchanger 20 (condenser) and the first expansion valve LEV1 and returns the refrigerant to the compressor 10, a second expansion valve LEV2 arranged in the bypass flow path 61, and an internal heat exchanger 121 that performs heat exchange between the refrigerant flowing from the indoor heat exchanger 20 (condenser) toward the branch point BP1 and the refrigerant that has passed through the second expansion valve LEV2.

[0079] Preferably, as shown in Fig. 8 and Fig. 9, the first fin portion is arranged in a predetermined frosting region A1 in the outdoor heat exchanger 40 (evaporator). The second fin portion is arranged in a predetermined non-frosting region A2 in the outdoor heat exchanger 40 (evaporator). The refrigeration cycle device 120 shown in Fig. 13 further includes a temperature sensor 111 arranged at the boundary between the frosting region A1 and the non-frosting region A2 in the outdoor heat exchanger 40 (evaporator). The control device 90 is configured to control the opening degree of the second expansion valve LEV2 based on the output of the temperature sensor 111, as shown in Fig. 14, so that the temperature at the boundary between the frosting region A1 and the non-frosting region A2 becomes 0°C.

[0080] Preferably, in the refrigeration cycle device 130 shown in FIG. 16, the refrigerant circuit 80 further includes a bypass flow path 62 that branches off from the refrigerant piping between the discharge port of the compressor 10 and the indoor heat exchanger 20 (condenser) and merges with the refrigerant piping that connects the first expansion valve LEV1 and the outdoor heat exchanger 40 (evaporator), and an expansion valve LEV3 that is arranged in the bypass flow path 62 and functions as a flow control valve.

[0081] More preferably, as shown in Fig. 8 and Fig. 9, the first fin portion is arranged in a predetermined frosting region A1 in the outdoor heat exchanger 40 (evaporator). The second fin portion is arranged in a predetermined non-frosting region A2 in the outdoor heat exchanger 40 (evaporator). The refrigeration cycle device 130 shown in Fig. 16 further includes a temperature sensor 111 arranged at the boundary between the frosting region A1 and the non-frosting region A2 in the outdoor heat exchanger 40 (evaporator). The control device 90 is configured to control the opening degree of the LEV3 based on the output of the temperature sensor 111, as shown in Fig. 17, so that the temperature at the boundary between the frosting region A1 and the non-frosting region A2 becomes 0°C.

[0082] Preferably, in the refrigeration cycle apparatus 140 shown in FIG. 19, the refrigerant circuit 80 further includes a heater 141 that heats the refrigerant flowing through the refrigerant pipe 54 that connects the first expansion valve LEV1 and the outdoor heat exchanger 40 (evaporator).

[0083] More preferably, as shown in Fig. 8 and Fig. 9, the first fin portion is arranged in a predetermined frost region A1 in the outdoor heat exchanger 40 (evaporator). The second fin portion is arranged in a predetermined non-frost region A2 in the outdoor heat exchanger 40 (evaporator). The refrigeration cycle device 140 shown in Fig. 19 further includes a temperature sensor 111 arranged at the boundary between the frost region A1 and the non-frost region A2 in the outdoor heat exchanger 40 (evaporator). The control device 90 is configured to control the amount of heat of the heater 141 based on the output of the temperature sensor 111, as shown in Fig. 20, so that the temperature at the boundary between the frost region A1 and the non-frost region A2 becomes 0°C.

[0084] 22, a refrigerant pipe 51, which is a part of a refrigerant pipe connecting a discharge port of the compressor 10 and an indoor heat exchanger 20 (condenser), preferably includes a first flow path 51A and a second flow path 51B provided in parallel to the first flow path 51A. The refrigerant circuit 80 further includes an internal heat exchanger 151 that exchanges heat between the refrigerant flowing from the first expansion valve LEV1 toward the outdoor heat exchanger 40 (evaporator) and the refrigerant flowing through the second flow path 51B, and a three-way valve 152 that switches whether the refrigerant discharged from the compressor 10 flows through the first flow path 51A or the second flow path 51B.

[0085] More preferably, as shown in Fig. 8 and Fig. 9, the first fin portion is arranged in a predetermined frosting region A1 in the outdoor heat exchanger 40 (evaporator). The second fin portion is arranged in a predetermined non-frosting region A2 in the outdoor heat exchanger 40 (evaporator). The refrigeration cycle device 150 shown in Fig. 22 further includes a temperature sensor 111 arranged at the boundary between the frosting region A1 and the non-frosting region A2 in the outdoor heat exchanger 40 (evaporator). The control device 90 is configured to control the three-way valve 152 based on the output of the temperature sensor 111 as shown in Fig. 23 so that the temperature at the boundary between the frosting region A1 and the non-frosting region A2 becomes 0°C.

[0086] Preferably, the refrigeration cycle apparatus 100 further includes a four-way valve 50 that can be connected to the refrigerant circuit 80 by switching the discharge port and the suction port of the compressor 10. The four-way valve 50 can switch the flow direction of the refrigerant flowing through the refrigerant circuit 80 between a first direction in which the refrigerant flows through the compressor 10, the indoor heat exchanger 20 (condenser), the first expansion valve LEV1, and the outdoor heat exchanger 40 (evaporator) in this order, and a second direction in which the refrigerant flows through the compressor 10, the outdoor heat exchanger 40 (evaporator), the first expansion valve LEV1, and the indoor heat exchanger 20 (condenser) in this order.

[0087] By configuring as above, the defrosting period can be extended by preventing uneven frosting, which leads to improved comfort on the load side. In addition, the average COP is improved by increasing the integrated heating capacity.

[0088] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0089] 10 compressor, 20, 40, 121, 151 heat exchanger, 50 four-way valve, 51 to 56 piping, 51A first flow path, 51B second flow path, 61, 62 bypass flow path, 80 refrigerant circuit, 90 control device, 91 CPU, 92 memory, 100, 110, 120, 130, 140, 150 refrigeration cycle device, 111 temperature sensor, 141 heater, 152 three-way valve, A1 frosting area, A2 non-frosting area, BP1, BP2 branch point, C12, C23, C34, C45, C56, C67, C89, C1011 connecting piping, L1, L2 fin group, LEV1, LEV2, LEV3 expansion valve, P1, P2, P3, P4 port, R1 to R12 heat transfer tube.

Claims

1. A refrigeration cycle device, a refrigerant circuit in which a compressor, a condenser, a first expansion valve, and an evaporator are connected by a refrigerant pipe; A non-azeotropic refrigerant flows through the refrigerant pipe, When the non-azeotropic refrigerant passes through the evaporator, a temperature difference occurs between the inlet and the outlet of the evaporator, The evaporator comprises: A group of fins stacked at intervals; a heat transfer tube penetrating the fin group in a stacking direction of the fin group and through which the non-azeotropic refrigerant flows, The fin group includes: A first fin portion on which frost may form in a humid environment; A second fin portion that is not frosted and ensures ventilation, The first fin portion is disposed in a predetermined frost region of the evaporator, The second fin portion is disposed in a predetermined non-frosting region of the evaporator, The refrigeration cycle device includes: a temperature sensor disposed on a boundary between the frosted region and the non-frosted region in the evaporator; A control device for controlling the refrigerant circuit is further provided. The control device controls the refrigerant circuit so that, when the temperature of the air exchanging heat with the evaporator is 0°C or higher, the temperature of the non-azeotropic refrigerant flowing through the portion of the heat transfer tube that penetrates the first fin portion is 0°C or lower, and the temperature of the non-azeotropic refrigerant flowing through the heat transfer tube of the second fin portion is 0°C or higher and lower than the temperature of the air.

2. The refrigeration cycle apparatus according to claim 1 , wherein the control device is configured to control an opening degree of the first expansion valve based on an output of the temperature sensor so that the boundary temperature becomes 0° C.

3. The refrigerant circuit includes: a bypass flow path that branches off from the refrigerant pipe that connects the condenser and the first expansion valve at a branch point and returns the refrigerant to the compressor; A second expansion valve disposed in the bypass flow path; 2. The refrigeration cycle apparatus according to claim 1, further comprising an internal heat exchanger that exchanges heat between the refrigerant flowing from the condenser toward the branch point and the refrigerant that has passed through the second expansion valve.

4. The refrigeration cycle apparatus according to claim 3 , wherein the control device is configured to control an opening degree of the second expansion valve based on an output of the temperature sensor so that the boundary temperature becomes 0° C.

5. The refrigerant circuit includes: a bypass flow path branching from the refrigerant piping between a discharge port of the compressor and the condenser and joining the refrigerant piping between the first expansion valve and the evaporator; The refrigeration cycle apparatus according to claim 1 , further comprising a flow rate adjustment valve disposed in the bypass flow path.

6. The refrigeration cycle apparatus according to claim 5 , wherein the control device is configured to control an opening degree of the flow rate adjustment valve based on an output of the temperature sensor so that the boundary temperature becomes 0° C.

7. The refrigerant circuit includes: The refrigeration cycle apparatus according to claim 1 , further comprising a heater that heats the refrigerant flowing through the refrigerant pipe that connects the first expansion valve and the evaporator.

8. The refrigeration cycle apparatus according to claim 7 , wherein the control device is configured to control an amount of heat of the heater based on an output of the temperature sensor so that the boundary temperature becomes 0° C.

9. A portion of the refrigerant piping connecting the discharge port of the compressor and the condenser is A first flow path; a second flow path provided in parallel to the first flow path, The refrigerant circuit includes: an internal heat exchanger that exchanges heat between a refrigerant flowing from the first expansion valve toward the evaporator and a refrigerant flowing through the second flow passage; The refrigeration cycle apparatus according to claim 1 , further comprising a flow path switching device that switches whether the refrigerant discharged from the compressor flows through the first flow path or the second flow path.

10. The refrigeration cycle apparatus according to claim 9 , wherein the control device is configured to control the flow path switching device based on an output of the temperature sensor so that the boundary temperature becomes 0° C.

11. A four-way valve is provided that can be connected to the refrigerant circuit by switching between a discharge port and a suction port of the compressor. The refrigeration cycle device according to any one of claims 1 to 10, wherein the four-way valve is capable of switching a flow direction of the refrigerant flowing through the refrigerant circuit between a first direction in which the refrigerant flows through the compressor, the condenser, the first expansion valve, and the evaporator in that order, and a second direction in which the refrigerant flows through the compressor, the evaporator, the first expansion valve, and the condenser in that order.

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