JP2008014602A - Refrigeration cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To not only to avoid the restriction of a constant density ratio by a bypass flow passage of an expansion device, but also to restrain a refrigerant flowing in the bypass flow passage not contributing to recover power, to the minimum, by carrying out internal heat exchange between the refrigerant in a heat radiator outlet side and the refrigerant in the bypass flow passage. <P>SOLUTION: This refrigeration cycle device has a main refrigerant circuit 501 connected sequentially in series with a compressor 101, the radiator 102, an internal heat exchanger 108, the expansion device 103 and an evaporator 104, and a bypass circuit 502 branched from the expansion device 103, and for connecting an outlet side of the expansion device 103 via the first flow control valve 105 and the internal heat exchanger 108, and a power recovery amount is thereby kept high while avoiding the limitation of the " density ratio=constant". <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus such as a water heater or an air conditioner, and relates to a configuration that realizes high efficiency.

  In the conventional refrigeration cycle system with both positive displacement compressors and expanders connected to a single shaft, the compressor and expander always rotate at the same rotational speed, so the system operates with a constant refrigerant circulation rate. In this case, the high efficiency operation cannot always be realized due to the limitation of the cycle operation of “density ratio = constant” even though the efficiency of the cycle is improved by the power recovery by the expander. There are challenges.

  FIG. 10 shows a refrigeration cycle configuration circuit using a bypass flow path for solving such a problem. Since this system is provided with a control valve 12 that increases or decreases the passage area of the bypass pipe 11, the refrigerant circulation amount passing through the expander 4 is adjusted to increase or decrease, and the mass circulation amount of the refrigerant passing through the compressor 3 side is adjusted. Unlike the mass circulation amount passing through the expander 4 side, the conventional restriction on cycle operation of “density ratio = constant” is eliminated. (For example, refer to Patent Document 1).

It has also been proposed to increase the refrigerant density ratio on the expander inlet side by providing an internal heat exchanger on the outlet side of the evaporator to cool the refrigerant at the expander inlet. In this case, in order to adjust the heat exchange amount, as shown in FIG. 11, the heat exchange amount in the internal heat exchanger is changed by controlling the flow control valves 10a and 10b, and the expander inflow refrigerant density is changed. There is one that effectively reduces the expansion power of the expander by reducing the change in the refrigerant density ratio that is the ratio of the refrigerant density to the compressor inflow refrigerant density. (For example, refer to Patent Document 2).
JP 2001-116371 A (FIG. 1) JP 2004-108683 A (FIG. 10)

  For example, in the case of a heat pump device in which the refrigeration cycle apparatus supplies hot water, the refrigeration cycle changes greatly depending on the season, so the density ratio between the compressor and the expander also changes greatly.

  Table 1 shows the ratio between the compressor suction density and the expander suction refrigerant density under each seasonal condition. As shown in Table 1, the density ratio is the largest in winter operation. This is because in the winter operation, the compressor suction density is low because the pressure on the low pressure side of the refrigeration cycle is low, while the suction density of the expander is high because the expander inlet temperature is low.

In the method using the bypass flow path of the expander as disclosed in Patent Document 1, if the suction volume of the expander and the compressor is adjusted in accordance with the winter operation, the refrigerant is completely contained in the bypass flow path in the winter operation. However, in summer operation, since the density ratio is small, the expander suction density is small, and the refrigerant flow rate conveyed by the compressor cannot be flowed by the expander. Therefore, during the summer operation, an operation of flowing the refrigerant through the bypass channel is performed, and this amount is 40% (= (10−6) / 10) of the refrigerant flow rate conveyed by the compressor. That is, the flow rate of refrigerant flowing through the expander is 60% of the flow rate of the compressor, and the power recovery amount is also 60%, so that the power recovery effect by the expander cannot be fully achieved.

  In the case of this patent document 1, since the refrigerant flowing through the pipe line bypassing the expander changes isentropic from the radiator outlet and merges with the expander outlet refrigerant, it does not contribute to improving the system efficiency at all. . Therefore, under the operating conditions where the flow rate of bypass refrigerant increases, the amount of expansion power recovered by the expander decreases, the effect of reducing the operating power of the compressor decreases, and high efficiency operation with the refrigeration air conditioner by power recovery cannot be expected. There was a point.

  In addition, as a method for solving this problem, Patent Document 2 intends to enable highly efficient operation with little reduction in the amount of recovered expansion power by changing the heat exchange amount of the internal heat exchanger according to the operation conditions. Was.

  However, the method of adjusting the refrigerant density using the internal heat exchanger has an insufficient amount of adjustment of the refrigerant density, and is not effective for a large change in the refrigerant density ratio as shown in Table 1. Met.

In order to solve the above problems, a refrigeration cycle apparatus according to the present invention passes through a compressor that compresses a refrigerant, a radiator that cools the refrigerant compressed by the compressor, and a refrigerant that is cooled by the radiator. An internal heat exchanger is connected directly to the compressor in a single axis and connects an expander that expands the refrigerant that has passed through the internal heat exchanger in the previous term and an evaporator that heats the refrigerant expanded by the expander. A main refrigerant circuit;
A first flow control valve that branches from between the internal heat exchanger and the expander and controls a refrigerant flow rate, a refrigerant that is cooled by the radiator and passes through the internal heat exchanger, and the first flow rate A first bypass passage connected between the expander and the evaporator via the internal heat exchanger that exchanges heat with the refrigerant that has passed through the control valve in order;

  With this configuration, it is possible to avoid the restriction of “density ratio = constant” while ensuring the maximum power recovery amount.

  Desirably, a first refrigerant temperature sensor for detecting a refrigerant temperature is further provided between the evaporator and the compressor.

  With this configuration, the degree of superheat can be optimally controlled while avoiding the restriction of “density ratio = constant”, so that the performance of the entire refrigeration cycle apparatus can be improved.

  Further, a second bypass flow path branched from the internal heat exchanger outlet side of the first bypass flow path and connected to the compressor via a second flow rate control valve for controlling the flow rate of the refrigerant. Is further included.

  More desirably, a second refrigerant temperature sensor for detecting the temperature of refrigerant discharged from the compressor is provided.

  With this configuration, the discharge temperature can be optimally controlled, so that the performance of the entire refrigeration cycle apparatus can be further improved.

Another refrigeration cycle apparatus of the present invention includes a compressor that compresses a refrigerant, a radiator that cools the refrigerant compressed by the compressor, and an internal heat exchanger through which the refrigerant cooled by the radiator passes. And a main refrigerant circuit that is connected directly to the compressor and uniaxially, expands the refrigerant that has passed through the internal heat exchanger in the previous period, and an evaporator that heats the refrigerant expanded by the expander. ,
A first flow control valve that branches from between the internal heat exchanger and the expander and controls a refrigerant flow rate, a refrigerant that is cooled by the radiator and passes through the internal heat exchanger, and the first flow rate A third bypass flow path that is injected into the expander via the internal heat exchanger that exchanges heat with the refrigerant that has passed through the control valve.

  The refrigeration cycle apparatus according to the present invention not only avoids the restriction of a constant density ratio by the bypass flow path of the expander, but also performs internal heat exchange between the refrigerant on the radiator outlet side and the refrigerant in the bypass flow path. The refrigerant flowing through the bypass channel that does not contribute to recovery can be suppressed to a minimum. That is, a high-efficiency refrigeration cycle can be realized while avoiding the restriction of a constant density ratio.

  As the refrigerant used in the refrigeration cycle apparatus of the present invention, various types of refrigerants such as chlorofluorocarbon and carbon dioxide can be used. In particular, it is appropriate that the refrigerant discharged from the compressor is in a supercritical state. Among them, it is most suitable for a system using carbon dioxide.

  Embodiments of the refrigeration cycle apparatus of the present invention will be described below with reference to the drawings.

(Embodiment 1)
As shown in FIG. 1, the refrigeration cycle apparatus 401 of the present embodiment includes a main refrigerant circuit 501 and a bypass channel 502.

  The main refrigerant circuit 501 includes a compressor 101 that boosts the refrigerant, a radiator 102 that cools the refrigerant that has been boosted by the compressor 101, and a refrigerant that is disposed downstream of the radiator 102 and cooled. A refrigerating cycle circuit is configured by sequentially connecting an expander 103 that extracts power by expanding under reduced pressure and an evaporator 104 that heats the refrigerant decompressed by the expander 103 by piping. Although not shown, the expander 103 and the compressor 101 are connected to a single shaft together with the electric motor, and the power recovered by the expander assists the electric motor to drive the compressor. Used as part.

  The main refrigerant circuit is provided with a first refrigerant temperature sensor 109 that detects the refrigerant intake refrigerant temperature. The temperature sensor may directly detect the refrigerant temperature or indirectly obtain the refrigerant temperature information by measuring the temperature of the refrigerant pipe.

  The first bypass flow path 502 connects the inlet portion and the outlet portion of the expander 103 via the first flow control valve 105. Furthermore, an internal heat exchanger 108 is provided to exchange heat between the outlet side refrigerant of the first flow control valve 105 and the outlet side refrigerant of the radiator 102 of the main refrigerant circuit 501.

  The control device 107 is a control device that controls the opening degree of the first flow control valve 105 in accordance with the detection signal of the first refrigerant temperature sensor 109.

  The operation of the refrigeration cycle apparatus configured as described above will be described with reference to the Mollier diagram of FIG.

  In FIG. 4, the refrigerant flow in the main refrigerant circuit 501 flowing through the expander 103 is indicated by A → B → C → D → E → A.

  Next, the refrigeration cycle when the refrigerant flows through the first bypass flow path 502 will be described. As shown in FIG. 4, the refrigerant state at the outlet of the radiator 102 is point C, but the refrigerant is moved to point D by the internal heat exchanger 108. Here, the refrigerant flowing through the first bypass flow path 105 is branched at the point D, and after being depressurized to the point F by the first flow control valve 105, the refrigerant moves to the point G by internal heat exchange, and the expander outlet It merges with the refrigerant and moves to point H. That is, by performing the internal heat exchange, the suction refrigerant density of the expander 103 is increased, so that the change in the density ratio can be reduced. The performance of the refrigeration cycle apparatus can be improved while avoiding the restriction of “density ratio = constant”.

  As described above, according to the present invention, for example, in the winter season, the first flow control valve 103 is fully closed, and in the summer season, the first flow control valve 103 is opened. Certain restrictions can be avoided. At this time, more desirably, the control of higher efficiency is possible by changing the opening of the first flow control valve 103 in the summer according to the conditions. Further, the opening degree of the first flow control valve 103 in winter may be adjusted according to conditions.

  Actually, the method for controlling the opening degree of the first flow control valve 103 is not particularly limited as long as it does not violate the restriction of the constant density ratio which is the main object of the present invention. As an example, the case of performing control based on the degree of superheat will be described next.

Here, the volume circulation amount of refrigerant passing through the compressor 101 is VC, the refrigerant suction density is DC, the volume circulation amount of refrigerant passing through the expander 103 is VE, the refrigerant suction density is DE, and the first flow rate When the opening degree of the control valve 105 is opened and the weight circulation amount ratio with respect to the whole refrigerant flowing through the first bypass flow path 502 is h, the weight circulation amount ratio of the refrigerant flowing through the expander 103 is (1-h). From what is shown
“VC × DC: VE × DE = 1: (1-h)”
That is, “VE × DE = (1−h) × VC × DC”
The relationship is established.

  Due to this relationship, when the refrigerant circulation amount flowing through the first bypass flow path 502 is increased, the refrigeration cycle balances so that the refrigerant density DC of the compressor suction increases. That is, in order to reduce the suction superheat degree of the compressor, the suction refrigerant density of the compressor 101 may be increased, so that the first flow control valve 105 provided in the first bypass flow path 502 is opened. Just increase the degree.

  Next, the flow of steps when the degree of superheat is measured to control the first flow control valve 105 will be described using the flowchart of FIG.

  When the control is started, the temperature of the outlet of the radiator 104 is measured by the first refrigerant temperature sensor 109 in step S200. A superheat degree T1 is calculated based on the measured refrigerant temperature measurement value. Next, the superheat degree T1 is compared with the target superheat degree TH1. Then, when the difference between the calculated superheat degree T1 and the target superheat degree TH1 is 0 or within a predetermined range, the control is terminated.

Next, when the difference between the superheat degree T1 and the target superheat degree TH1 is a predetermined value or more, the process proceeds to step S201. In step S201, it is determined whether T1 is larger than TH1 or smaller. If T1 is greater than TH1, the process proceeds to step S202, and control is performed to increase the opening of the first flow control valve 105. If the opening degree of the first flow control valve 105 is increased, the flow rate of the refrigerant flowing through the bypass flow path 502 is increased, so that the degree of superheat T1 is balanced so as to be reduced. If T1 is equal to or lower than TH1 in step S201, the process proceeds to step S203, where control is performed to reduce the opening of the first flow control valve 105. As a result, the degree of superheat T1 is balanced so as to increase, so that it can be controlled to approach the target value. And after step S202 or S203, it returns to step S200 and repeats S200-S203. The process is repeated until it is determined in S200 that the superheat degree T1 matches the target superheat degree TH1.

  As described above, the refrigeration cycle apparatus according to the present embodiment adjusts the opening degree of the first flow rate adjustment valve 105 to minimize power recovery amount reduction while maintaining a “density ratio = constant”. Restrictions can be avoided. That is, the refrigerant flowing through the bypass channel does not simply adjust the density ratio, but can cool the refrigerant at the expander inlet in the internal heat exchanger to further reduce the expander inlet refrigerant density. As a result, it contributes to the adjustment of the refrigerant density ratio.

  In addition, as described above, the degree of superheat can be optimally controlled by controlling the opening degree of the first flow rate adjustment valve by superheat degree control.

  Furthermore, when the refrigerant does not flow through the first bypass flow path 502, it indicates that the refrigeration cycle is in an optimum state, and at this time, the internal heat exchange amount becomes zero. That is, since the suction density of the expander 103 is smaller than that in the case of performing internal heat exchange, the lower limit value of the design suction density ratio between the expander 103 and the compressor 101 can be set as high as possible.

  Next, the features of the present invention will be described in comparison with similar comparative examples.

  As described above, as means for avoiding the restriction of “density ratio = constant”, there are a method using a bypass circuit of an expander described in Patent Document 1 and a method using an internal heat exchanger. When these two methods are combined, for example, as shown in FIG. 12, the configuration of the refrigeration cycle apparatus 404 of Comparative Example 1 can be considered.

  In Comparative Example 1, most of the configuration is the same as that of the first embodiment. The main refrigerant circuit 501 of the comparative example 1 is basically the same as the main refrigerant circuit of the first embodiment. In the first comparative example, the first expander is bypassed, the bypass circuit 505 is routed through the first flow rate adjustment valve, and is branched from the radiator 104 outlet side, and is routed through the third flow rate adjustment valve 130. A bypass circuit 506 is provided for exchanging heat with the refrigerant on the outlet side of the radiator 108 in the internal heat exchanger 108 and returning to the main refrigerant circuit 501 on the compressor inlet side.

  One of the problems of the configuration of Comparative Example 1 is that an evaporator is further provided on the outlet side of the evaporator, and the amount of heat exchange varies depending on the opening of the third flow rate adjustment valve 130. The temperature of the suction refrigerant is likely to fluctuate. In Embodiment 1, since the internal heat exchange amount is adjusted before flowing into the evaporator, there is an advantage that such fluctuations are suppressed.

  Further, in Comparative Example 1, two flow rate adjustment valves 105 and 130 are required to adjust the bypass amount and the internal heat exchange amount. There is also a merit that it can be done. Since only one flow rate adjusting valve is required, not only the cost is reduced, but also control is simplified.

Next, as a variation of the comparative example 1, a configuration of the refrigeration cycle apparatus 405 of the comparative example 2 as shown in FIG. 13 can be considered. In Comparative Example 2, unlike Comparative Example 1, the refrigerant flowing through the low-pressure-side internal heat exchanger 108 uses a bypass flow path 507 that is branched on the entry side of the evaporator 104.

  In Comparative Example 2, as in Comparative Example 1, two flow rate adjustment valves 105 and 130 are required to adjust the bypass amount and the internal heat exchange amount. In the first embodiment, these are combined. There is an advantage that only one is required. Since only one flow rate adjusting valve is required, not only the cost is reduced, but also control is simplified.

  As another variation of the first comparative example, a configuration in which all the refrigerant passes through the internal heat exchanger 108 without connecting the main refrigerant circuit 501a corresponding to the bypass circuit 506 is also conceivable. In this case, it is not necessary to provide the flow rate adjusting valve 130 and only one flow rate adjusting valve 105 is required. However, in this case, it becomes difficult to control the heat exchange amount of the internal heat exchanger. In Comparative Example 2, the same applies when the part 501b of the main refrigerant circuit is not provided.

  In the case of Comparative Example 1, it is necessary to provide not only the flow rate control valve 130 but also a new bypass circuit 506. In the first embodiment, it is not necessary to provide this new bypass circuit. There is an advantage that the space can be made smaller and the size can be reduced. Even if it is compared with the case where the bypass circuit 507 is not provided in the comparative example 2, there is exactly the same merit.

(Embodiment 2)
FIG. 2 is a configuration diagram of the refrigeration cycle apparatus 402 of the second embodiment. Regarding the configuration of the refrigeration cycle apparatus of the present example, differences from the first embodiment will be described.

  The refrigeration cycle apparatus 402 according to the present embodiment includes a second bypass flow path 503 that connects the outlet side of the internal heat exchanger 108 of the first bypass flow path 502 and the compressor 101 via the second flow control valve 111. The second refrigerant temperature sensor 112 for detecting the temperature of the refrigerant discharged from the compressor is provided. The temperature sensor may directly detect the refrigerant temperature or indirectly obtain the refrigerant temperature information by measuring the temperature of the refrigerant pipe.

  The refrigerant from the second bypass circuit is injected into the compressor 101 in the intermediate process of compression. The format of the compressor is not particularly limited, but here, a case where a scroll compressor is used will be described.

  The compressor shown in FIG. 9 is a scroll-type compressor that compresses gas by orbiting the orbiting scroll 122 relative to the fixed scroll 121. A bypass port 120 shown in FIG. 9 is provided in the middle part of the compressor. The refrigerant that has joined at the bypass port 120 moves toward the center of the scroll while being reduced in volume by the rotational movement of the orbiting scroll 122 and is discharged.

  The refrigeration cycle apparatus configured as described above will be described with reference to the Mollier diagram of FIG.

  In the Mollier diagram of FIG. 5, the refrigerant flow in the main refrigerant circuit flowing through the expander 103 is indicated by A → B → C → D → E → A. Here, the refrigerant flowing through the first bypass passage 502 is branched at point D, and after being depressurized to point I by the first flow control valve 105, it moves to point J by internal heat exchange. Next, the refrigerant flowing through the second bypass flow path 503 is branched at point J and injected into the compressor 101 at point K. Further, the refrigerant branched from the point J and flowing through the first bypass channel 502 moves to the point L.

  Here, when the opening degree of the second flow rate control valve 111 provided in the second bypass flow path 503 is increased and the amount of refrigerant circulating through the second bypass flow path 503 is increased, the specific enthalpy at the K point is Since it becomes smaller, the discharge temperature (point B) of the compressor 101 can be controlled to be small.

  That is, when the refrigerant circulation amount flowing through the second bypass flow path 503 is increased, the refrigeration cycle is balanced so that the compressor discharge temperature is decreased. That is, in order to increase the discharge temperature of the compressor 101, the opening degree of the second flow control valve 111 provided in the second bypass flow path 503 may be decreased.

  Here, the control of the first and second flow control valves 105 and 111 will be described with reference to the flowchart of FIG.

  When the control is started, first, the first flow control valve 105 is controlled in steps S300 to S303. Since this is exactly the same as the control in steps S200 to S203 of the first embodiment, description thereof is omitted.

  Next, in step S304, the refrigerant discharge temperature T2 of the compressor is measured by the second refrigerant temperature sensor 112. Next, the refrigerant discharge temperature T2 is compared with the target discharge temperature TH2. Then, when the difference between the measured discharge temperature T2 and the target discharge temperature TH2 is 0 or within a predetermined range, the control is terminated.

  Next, when the difference between the measured discharge temperature T2 and the target discharge temperature TH2 is equal to or greater than a predetermined value, the process proceeds to step S305. In step S305, it is determined whether T2 is larger or smaller than TH2. If T2 is greater than TH2, the process proceeds to step S306, and control is performed to increase the opening of the second flow control valve 111. If the opening degree of the second flow control valve 111 is increased, the flow rate of the refrigerant flowing through the second bypass flow path 503 increases, so that the discharge temperature T2 is balanced so as to decrease. If T1 is smaller than TH1 in step S305, the process proceeds to step S307, and control is performed to reduce the opening of the second flow control valve 111. As a result, the discharge temperature T2 is balanced so as to increase, so that the discharge temperature T2 can be controlled to approach the target value. And after step S306 or S307, it returns to step S304 and repeats S304-S307. The process is repeated until it is determined in S304 that the discharge temperature T2 matches the target discharge temperature TH2.

  As described above, by adjusting the opening degree of the first and second flow rate adjusting valves 105 and 111, the restriction of “density ratio = constant” is avoided while minimizing power recovery amount reduction. be able to.

In addition, as described above, the degree of superheat is controlled by controlling the opening degree of the first flow rate adjustment valve by controlling the degree of superheat, and controlling the second flow rate adjustment valve by the refrigerant discharge refrigerant temperature. The compressor discharge temperature can be optimally controlled.
(Embodiment 3)
FIG. 3 is a configuration diagram of the refrigeration cycle apparatus 403 according to the third embodiment of the present invention. Regarding the configuration of the refrigeration cycle apparatus of the present embodiment, differences from the first embodiment will be described.

  A feature of the refrigeration cycle apparatus of the present embodiment is that the outlet side of the internal heat exchanger 108 of the bypass channel 502 is injected into the expander 103.

The expander 103 is injected with the refrigerant from the bypass circuit 504 in the intermediate process of expansion. The type of the expander is not particularly limited, but here, a case where a scroll type expander is used will be described.

  The expander shown in FIG. 14 is a scroll type expander in which the orbiting scroll 142 is swung with respect to the fixed scroll 141 to expand the gas. The bypass port 140 is provided in the middle part of the expander. The refrigerant that has joined at the bypass port 140 moves from the center of the scroll to the peripheral direction while being increased in volume by the rotational movement of the orbiting scroll 142, and is discharged.

  The refrigeration cycle apparatus configured as described above will be described with reference to FIG.

  In the Mollier diagram of FIG. 6, the refrigerant flow in the main refrigerant circuit 501 flowing through the expander 103 is indicated by A → B → C → D → M → P → Q → A. Here, the refrigerant flowing through the first bypass flow path 504 is branched at a point D, depressurized to a point R by the first flow control valve 105, and then moved to a point N by internal heat exchange. Next, the refrigerant flowing through the third bypass flow path 504 is injected into the expander 103, merges with the refrigerant flowing through the expander 103, and moves to the point P. After that, it expands under reduced pressure by the expander 103, moves to the point Q, is heated by the evaporator 104, and returns to the point A.

  That is, the refrigeration cycle apparatus according to the present embodiment can not only avoid the restriction of “density ratio = constant” but also increase the amount of recovered power by injecting the refrigerant flowing through the bypass flow path 504 into the expander 103. Is possible.

  The refrigeration cycle apparatus according to the present invention can be used not only as a water heater and an air conditioner but also as a refrigeration cycle apparatus for other uses such as tableware drying and garbage disposal.

The block diagram which shows the refrigerating-cycle apparatus in Embodiment 1 of this invention. The block diagram which shows the refrigerating-cycle apparatus in Embodiment 2 of this invention. The block diagram which shows the refrigerating-cycle apparatus in Embodiment 3 of this invention. Mollier diagram showing the refrigeration cycle in Embodiment 1 of the present invention Mollier diagram showing the refrigeration cycle in Embodiment 2 of the present invention Mollier diagram showing the refrigeration cycle in Embodiment 3 of the present invention Control flowchart of refrigeration cycle apparatus in Embodiment 1 of the present invention Control flowchart of refrigeration cycle apparatus in Embodiment 2 of the present invention The figure which shows an example of the bypass port provided in the compressor The block diagram which shows the refrigerating-cycle apparatus of patent document 1 The block diagram which shows the refrigerating-cycle apparatus of patent document 1 The block diagram which shows the refrigerating-cycle apparatus of the comparative example 1. The block diagram which shows the refrigerating-cycle apparatus of the comparative example 1. The figure which shows an example of the bypass port provided in the expander

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Compressor 102 Radiator 103 Expander 104 Evaporator 105 1st flow control valve 106 1st bypass flow path 107 Control apparatus 108 Internal heat exchanger 109 1st refrigerant | coolant temperature sensor 110 2nd bypass flow path 111 1st Second flow control valve 112 Second refrigerant temperature sensor 120 Bypass port

Claims (5)

A compressor that compresses the refrigerant, a radiator that cools the refrigerant compressed by the compressor, an internal heat exchanger through which the refrigerant cooled by the radiator passes, and a direct connection to the compressor are provided. A main refrigerant circuit that connects an expander that expands the refrigerant that has passed through the internal heat exchanger in the previous period and an evaporator that heats the refrigerant expanded in the expander,
A first flow control valve that branches off from the main refrigerant circuit between the internal heat exchanger and the expander and controls a refrigerant flow rate; a refrigerant that is cooled by the radiator and passes through the internal heat exchanger; The first heat exchanger connected to the main refrigerant circuit between the expander and the evaporator is sequentially passed through the internal heat exchanger that exchanges heat with the refrigerant that has passed through the first flow control valve. A refrigeration cycle apparatus having a bypass flow path.   The refrigeration cycle apparatus according to claim 1, further comprising a first refrigerant temperature sensor for detecting a refrigerant temperature in a main refrigerant circuit between the evaporator and the compressor.   A second bypass channel that branches from the outlet side of the internal heat exchanger of the first bypass channel and is connected to the compressor via a second flow rate control valve that controls the flow rate of the refrigerant is further provided. The refrigeration cycle apparatus according to claim 1.   The refrigeration cycle apparatus according to claim 3, further comprising a second refrigerant temperature sensor that detects a temperature of refrigerant discharged from the compressor. A compressor that compresses the refrigerant, a radiator that cools the refrigerant compressed by the compressor, an internal heat exchanger through which the refrigerant cooled by the radiator passes, and a direct connection to the compressor are provided. A main refrigerant circuit that connects an expander that expands the refrigerant that has passed through the internal heat exchanger in the previous period, and an evaporator that heats the refrigerant expanded in the expander,
A first flow control valve that branches off from the main refrigerant circuit between the internal heat exchanger and the expander and controls a refrigerant flow rate; a refrigerant that is cooled by the radiator and passes through the internal heat exchanger; A refrigeration cycle apparatus having a third bypass flow path that is injected into the expander through the internal heat exchanger that exchanges heat with the refrigerant that has passed through the first flow control valve.

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