Ejector Refrigeration System

Abstract

To provide an ejector refrigerating device that can restrain decreases in refrigeration capacity and device efficiency from occurring when a hybrid type refrigeration cycle in which a compressor is introduced into an ejector refrigeration cycle is applied.SOLUTION: A control unit C switches to an ejector mode of turning off a compressor 7, and making a refrigerant from an evaporator 6 flow to a suction inlet 1b via a switching mechanism 9, when a pressure ratio of a back pressure Pd to a compressor pressure Ps is lower than a first threshold value, switches to a parallel hybrid mode of turning on the compressor 7, and making the refrigerant from the compressor 7 flow to a discharge port 1c via the switching mechanism 9, when the pressure ratio is equal to or higher than the first threshold value and lower than a second threshold value, and switches to a serial hybrid mode of turning on the compressor 7, and making the refrigerant from the compressor 7 flow to the suction inlet 1b via the switching mechanism 9, when the pressure ratio is equal to or higher than the second threshold value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an ejector refrigeration apparatus capable of suppressing a decrease in refrigeration capacity and apparatus efficiency when applying a hybrid refrigeration cycle in which a compressor is introduced into an ejector refrigeration cycle. Background Art

[0002] As ejector refrigeration apparatuses, for example, those described in Patent Document 1 have already been provided. In this ejector refrigeration apparatus, an ejector is provided between a steam generator serving as refrigerant heating means and a condenser in a circulation path through which a refrigerant circulates, and the refrigerant discharged from the steam generator is supplied to the ejector as a driving fluid, while the refrigerant discharged from the ejector is supplied to the condenser. A branch path is provided in a portion of the circulation path located between the condenser and a pump. The branch path is provided with an expansion valve and an evaporator, and supplies the refrigerant that has passed through the evaporator to the ejector as a suction fluid. In this ejector refrigeration apparatus, if a heat source such as waste warm water is supplied to the steam generator and water to be cooled is supplied to the evaporator, cooled cold water can be obtained from the evaporator.

[0003] Since the ejector refrigeration cycle of an ejector refrigeration apparatus can be driven only by a pump, power consumption can be suppressed compared to a compression refrigeration cycle using a compressor. However, if the temperature of cooling water flowing through the condenser is high, the back pressure of the ejector increases, which may cause a significant decrease in refrigeration capacity and apparatus efficiency.

[0004] For this reason, Patent Document 2 proposes an ejector refrigeration apparatus incorporating a compressor. One of them connects a compressor and an ejector in series, and reduces the discharge pressure of the compressor by means of the ejector, thereby reducing the power consumption of the compressor. Further, as another configuration, one in which a compressor and an ejector are arranged in parallel has been proposed. Prior Art Documents Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-190587 [Patent Document 2] Japanese Patent Publication No. 2011-94814 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Incidentally, as shown in Figure 6, in a series hybrid refrigeration cycle system in which the compressor 7 and ejector 1 are connected in series, the power consumption of the compressor 7 can be reduced. However, if the back pressure of the ejector 1 is low, the ejector 1 functions sufficiently, resulting in a very small differential pressure across the compressor 7. The compressor 7 requires a certain pressure difference across it, and if the pressure difference is small, its reliability decreases due to poor oil circulation, etc. Furthermore, as shown in Figure 7, the efficiency of the compressor 7 decreases significantly in the low compression ratio region. For this reason, in a series hybrid refrigeration cycle system, the compressor is only used under conditions where a certain pressure difference can be maintained.

[0007] Here, the refrigeration capacity of the ejector refrigeration cycle decreases significantly depending on the cooling water temperature, so it is desirable to switch to a series hybrid refrigeration cycle that incorporates a compressor. However, as shown in Figure 8, when switching to operation using a compressor, a region EB occurs where the compressor cannot be operated due to constraints on the compressor's compression ratio, resulting in a region where the refrigeration capacity decreases.

[0008] On the other hand, as shown in Figure 9, in a parallel hybrid type refrigeration cycle system in which the compressor 7 and ejector 1 are arranged in parallel, a sufficient pressure difference is generated in the compressor 7, so there is no decrease in the performance or reliability of the compressor 7, and the refrigeration capacity does not decrease in region EB. However, because the compressor 7 and ejector 1 are arranged in parallel, the pressure difference between the suction and discharge of the ejector also increases. Therefore, as shown in Figure 10, in the high back pressure region, the ejector 1 does not drive, and there is a problem that a sufficient performance improvement effect cannot be obtained.

[0009] The present invention has been made in view of the above, and aims to provide an ejector refrigeration system that can suppress the occurrence of a decrease in refrigeration capacity and equipment efficiency when a hybrid type refrigeration cycle is applied in which a compressor is introduced into the ejector refrigeration cycle. [Means for solving the problem]

[0010] To achieve the above objective, the present invention provides an ejector refrigeration system comprising: a pump for pressurizing a refrigerant; a steam generator for heating the refrigerant with heat source water supplied from a heat supply source to generate an ejector drive flow; an expansion valve for reducing the pressure of the refrigerant; an evaporator for cooling a medium to be cooled with the refrigerant reduced in pressure by the expansion valve; an ejector for drawing in the refrigerant evaporated by the evaporator with the ejector drive flow of the refrigerant from the steam generator; and a condenser for cooling the refrigerant mixed with the ejector drive flow after being drawn into the ejector, wherein the system comprises: a compressor disposed between the evaporator and the ejector for compressing the refrigerant from the evaporator; a switching mechanism for switching at least between the connection of the compressor to the suction inlet of the ejector and the connection of the compressor to the discharge port of the ejector; an on / off valve connected in parallel to the compressor; and a compressor pressure, which is the refrigerant pressure on the suction side of the compressor. The system is characterized by comprising: a compressor pressure sensor; a back pressure sensor that detects the back pressure, which is the refrigerant pressure on the discharge side of the ejector; and a control unit that, when the pressure ratio of the back pressure to the compressor pressure is less than a first threshold, switches to an ejector mode in which the compressor is turned off and the on-off valve is opened, allowing the refrigerant from the evaporator to flow to the suction inlet of the ejector via the switching mechanism; when the pressure ratio is greater than or equal to the first threshold and less than a second threshold, switches to a parallel hybrid mode in which the compressor is turned on and the on-off valve is opened, allowing the refrigerant from the compressor to flow to the discharge port of the ejector via the switching mechanism; and when the pressure ratio is greater than or equal to the second threshold, switches to a series hybrid mode in which the compressor is turned on and the on-off valve is closed, allowing the refrigerant from the compressor to flow to the suction inlet of the ejector via the switching mechanism.

[0011] Furthermore, the present invention is characterized in that, in the above invention, a heat source water temperature sensor is provided to detect the temperature of the heat source water supplied to the steam generator, and the control unit switches to a compression mode in which, when the temperature of the heat source water is below a predetermined threshold temperature, the compressor is turned on, the pump is turned off, the on / off valve is closed, and the refrigerant from the compressor flows to the discharge port of the ejector via the switching mechanism.

[0012] Furthermore, the present invention, in the above invention, comprises a switching mechanism comprising: a first pipe connecting the compressor and the discharge port of the ejector; a second pipe connecting the on-off valve and the suction inlet of the ejector; a connecting pipe connecting the first pipe and the second pipe; a first on-off valve provided between the connection point of the first pipe to which the connecting pipe is connected and the discharge port of the ejector; and a second on-off valve provided on the connecting pipe, wherein the control unit closes the first on-off valve and the second on-off valve in the ejector mode, opens the first on-off valve and closes the second on-off valve in the parallel hybrid mode, and closes the first on-off valve and opens the second on-off valve in the series hybrid mode.

[0013] Furthermore, the present invention, in the above invention, comprises a first pipe connecting the compressor and the discharge port of the ejector, a second pipe connecting the on-off valve and the suction inlet of the ejector, a connecting pipe connecting the first pipe and the second pipe, a first on-off valve provided between the connection point of the first pipe to which the connecting pipe is connected and the discharge port of the ejector, and a second on-off valve provided on the connecting pipe, wherein the control unit closes the first on-off valve and the second on-off valve in the ejector mode, opens the first on-off valve and closes the second on-off valve in the parallel hybrid mode, closes the first on-off valve and opens the second on-off valve in the series hybrid mode, and opens the first on-off valve and closes the second on-off valve in the compression mode.

[0014] Furthermore, the present invention is characterized in that, in the above invention, the on-off valve is a check valve. [Effects of the Invention]

[0015] According to the present invention, when applying a hybrid refrigeration cycle that incorporates a compressor into an ejector refrigeration cycle, it is possible to suppress the occurrence of a decrease in refrigeration capacity and equipment efficiency. [Brief explanation of the drawing]

[0016] [Figure 1] Fig. 1 is a circuit diagram showing the configuration of an ejector refrigeration apparatus according to an embodiment of the present invention. [Figure 2] Fig. 2 is a diagram showing changes in operation mode efficiency and refrigeration capacity with respect to a pressure ratio (Pd / Ps). [Figure 3] Fig. 3 is a diagram showing switching states of a compressor, a pump, and an opening-closing valve corresponding to operation modes. [Figure 4] Fig. 4 is a flowchart showing a mode switching process procedure for an operation mode performed by a control unit. [Figure 5] Fig. 5 is a diagram showing an equivalent circuit in an ejector mode. [Figure 6] Fig. 6 is a diagram showing an equivalent circuit in a series hybrid mode. [Figure 7] Fig. 7 is a diagram showing efficiency characteristics of the compressor with respect to a pressure ratio (Pd / Ps). [Figure 8] Fig. 8 is a diagram showing changes in efficiency and refrigeration capacity in a series hybrid mode with respect to a pressure ratio (Pd / Ps). [Figure 9] Fig. 9 is a diagram showing an equivalent circuit in a parallel hybrid mode. [Figure 10] Fig. 10 is a diagram showing changes in efficiency and refrigeration capacity in a parallel hybrid mode with respect to a pressure ratio (Pd / Ps). DESCRIPTION OF EMBODIMENTS

[0017] Embodiments of the present invention will be described below with reference to the accompanying drawings.

[0018] <Overall Configuration> Figure 1 is a circuit diagram showing the configuration of an ejector refrigeration system according to an embodiment of the present invention. The ejector refrigeration system illustrated here recovers waste heat from waste hot water such as factory wastewater or used cooling water as heat source water and generates chilled water by cooling the medium to be cooled. A compression refrigeration cycle using a compressor 7 is applied to the ejector refrigeration cycle. The medium to be cooled can be water, oil, air, or other refrigerants. In this embodiment, in particular, an ejector refrigeration system that generates chilled water from the water to be cooled using waste heat recovered from waste hot water is illustrated.

[0019] The ejector refrigeration system has a circulation path in which an ejector 1, a condenser 2, a pump 3, and a steam generator 4 are sequentially connected. In addition, at branching point P1 between the condenser 2 and the pump 3, a portion of the refrigerant flowing through the circulation path is supplied to the ejector 1 as an intake fluid.

[0020] The refrigerant branched off from branching point P1 is supplied to the ejector 1 side via the expansion valve 5 and evaporator 6. Downstream of the evaporator 6, the compressor 7 and check valve 8 are connected in parallel from branching point P2 and connected to the switching mechanism 9. The refrigerant discharged from the compressor 7 is connected to the suction inlet 1b or discharge port 1c of the ejector 1 by the switching mechanism 9. The refrigerant supplied from the steam generator 4 is input as a drive flow to the drive inlet 1a of the ejector 1, and this drive flow draws the refrigerant in as a suction flow from the suction inlet 1b and discharges it from the discharge port 1c.

[0021] Pump 3 is responsible for circulating and supplying the refrigerant in the circulation path. Pump 3 is, for example, a liquid-phase variable displacement pump that pressurizes the refrigerant and supplies it to the ejector 1. Pump 3 is driven at a rotational speed according to the drive signal provided by the control unit C, which will be described later. The steam generator 4 evaporates the refrigerant supplied by pump 3 by performing heat exchange with heat source water, such as waste hot water, supplied to the steam generator 4 from the heat supply source 20.

[0022] The condenser 2 condenses the refrigerant by exchanging heat between the gaseous refrigerant discharged from the ejector 1 and the cooling water supplied to the condenser 2, thereby releasing heat. The expansion valve 5 expands and reduces the pressure of the refrigerant that has passed through the condenser 2 and been supplied via the branch point P1. The evaporator 6 evaporates the refrigerant and generates chilled water by exchanging heat between the liquid phase refrigerant after it has passed through the expansion valve 5 and the water to be cooled supplied to the evaporator 6. An electronic expansion valve is preferred as the expansion valve 5, but other types of expansion valves such as manual expansion valves, constant-pressure expansion valves, and temperature expansion valves may be appropriately selected depending on the application and configuration. The compressor 7 can be any compressor capable of compressing the refrigerant.

[0023] The switching mechanism 9 includes a first pipe connecting the compressor 7 and the discharge port 1c of the ejector 1, a second pipe connecting the check valve 8 and the suction inlet 1b of the ejector 1, and a connecting pipe connecting the connection point 9a of the first pipe and the connection point 9b of the second pipe. An on-off valve V1 is provided between the connection point 9a and the discharge port 1c of the ejector 1, and an on-off valve V2 is provided in the connecting pipe.

[0024] In this embodiment, the compressor 7, check valve 8, and switching mechanism 9 allow switching between four operating modes: ejector mode, parallel hybrid mode, series hybrid mode, and compression mode (see Figure 3). In ejector mode, the compressor 7 is off, the pump 3 is on, the on-off valve V1 is closed, and the on-off valve V2 is closed, resulting in an ejector refrigeration cycle using only the ejector 1 shown in Figure 5. This ejector mode can be driven with low power consumption because the compressor 7 is stopped, but it cannot be driven under high back pressure.

[0025] In parallel hybrid mode, the compressor 7 is on, the pump 3 is on, the on-off valve V1 is open, and the on-off valve V2 is closed. In this mode, the refrigerant from the evaporator 6 is split into two: one drawn into the compressor 7 and the other drawn through the check valve 8 to the suction inlet 1b of the ejector 1. The refrigerant compressed by the compressor 7 and the refrigerant compressed by the ejector 1 merge upstream of the condenser 2 and are sent to the condenser 2. A heat exchanger, such as an internal heat exchanger, may be provided upstream of the condenser 2. This parallel hybrid mode is effective under medium back pressure conditions because the compressor 7 can compensate for the reduction in the refrigeration capacity of the ejector 1.

[0026] In series hybrid mode, the compressor 7 is on, the pump 3 is on, the on-off valve V1 is closed, and the on-off valve V2 is open. In this mode, the refrigerant from the evaporator 6 is drawn into the compressor 7 and then drawn into the suction inlet 1b of the ejector 1. In this series hybrid mode, the ejector 1 can lower the discharge pressure of the compressor 7, thus reducing the power consumption of the compressor 7 and achieving a higher efficiency (COP) than conventional compression refrigeration cycles. The series hybrid mode is effective under medium to high back pressure conditions.

[0027] In compression mode, the compressor 7 is on, the pump 3 is off, valve V1 is open, and valve V2 is closed. This mode is a general compression refrigeration cycle, not an ejector refrigeration cycle. Compression mode is the least efficient, but it can be operated even without a heat source such as waste heat water. In other words, even if a heat source for the heat source water supplied from the heat supply source 20 is unavailable, this ejector refrigeration system can be operated stably without stopping.

[0028] The compressor pressure sensor S1 detects the compressor pressure Ps, which is the refrigerant pressure on the suction side of the compressor 7. The back pressure sensor S2 detects the back pressure Pd, which is the refrigerant pressure on the discharge side of the ejector 1. Furthermore, the heat source water temperature sensor S3 detects the heat source water temperature Tw, which is the heat source water supplied to the steam generator 4.

[0029] The control unit C detects the refrigerant pressure and temperature, the heat source water temperature, etc., and controls the pump 3, expansion valve 5, compressor 7, switching mechanism 9, etc. In particular, the control unit C detects the compressor pressure Ps, back pressure Pd, and heat source water temperature Tw, and controls the switching of the operating mode. When controlling the switching of the operating mode, the control unit C uses the pressure ratio of the back pressure Pd to the compressor pressure Ps (Pd / Ps).

[0030] <Efficiency and cooling capacity for each operating mode> Figure 2 shows the change in operating mode efficiency and refrigeration capacity with respect to the pressure ratio (Pd / Ps). As shown in Figure 2, in the low back pressure region E1 where the pressure ratio (Pd / Ps) is less than the first threshold R12, the efficiency and refrigeration capacity of the ejector mode are high, as shown by curve M1. In the medium back pressure region E2 where the pressure ratio (Pd / Ps) is greater than or equal to the first threshold R12 and less than the second threshold R23, the efficiency and refrigeration capacity of the parallel hybrid mode are high, as shown by curve M2. Furthermore, in the high back pressure region E3 where the pressure ratio (Pd / Ps) is greater than or equal to the second threshold R23, the efficiency and refrigeration capacity of the series hybrid mode and compression mode are high, as shown by curves M3 and M4. Therefore, the control unit C switches to the ejector mode when the pressure ratio (Pd / Ps) is in region E1, switches to the parallel hybrid mode when the pressure ratio (Pd / Ps) is in region E2, and switches to the series hybrid mode when the pressure ratio (Pd / Ps) is in region E3. The switching control details for the compressor 7, pump 3, on-off valve V1, and on-off valve V2 for each operating mode are as shown in Figure 3, as described above.

[0031] <Mode switching process> Figure 4 is a flowchart showing the operation mode switching procedure performed by the control unit C. As shown in Figure 4, the control unit C first measures the heat source water temperature Tw, compressor pressure Ps, and back pressure Pd (step S101). Then, it determines whether the heat source water temperature Tw is less than a predetermined threshold temperature Tth (step S102). If the heat source water temperature Tw is less than the predetermined threshold temperature Tth (step S102: Yes), it switches the operation mode to compression mode (step S103) and terminates this process.

[0032] On the other hand, if the heat source water temperature Tw is not below a predetermined threshold temperature Tth (step S102: No), it is further determined whether the pressure ratio (Pd / Ps) is less than the first threshold R12 (step S104). If the pressure ratio (Pd / Ps) is less than the first threshold R12 (step S104: Yes), the operating mode is switched to ejector mode (step S105), and this process is terminated.

[0033] If the pressure ratio (Pd / Ps) is not less than the first threshold R12 (step S104: No), it is further determined whether the pressure ratio (Pd / Ps) is less than the second threshold R23 (step S106). If the pressure ratio (Pd / Ps) is less than the second threshold R23 (step S106: Yes), the operating mode is switched to parallel hybrid mode (step S107), and this process is terminated.

[0034] On the other hand, if the pressure ratio (Pd / Ps) is not less than the second threshold R23 (step S106: No), the operating mode is switched to series hybrid mode (step S108), and this process is terminated.

[0035] Conventionally, in a series hybrid refrigeration cycle, as shown in Figure 8, the compressor 7 cannot operate in the medium back pressure region EB, resulting in reduced efficiency and refrigeration capacity. However, in this embodiment, by switching to a parallel hybrid mode in this medium back pressure region EB, the reduction in efficiency and refrigeration capacity can be suppressed.

[0036] Furthermore, in conventional parallel hybrid refrigeration cycles, efficiency and refrigeration capacity decrease in the high back pressure region, as shown in Figure 10. However, in this embodiment, the decrease in efficiency and refrigeration capacity can be suppressed by switching to a series hybrid mode in this high back pressure region.

[0037] In this embodiment, in an ejector refrigeration system incorporating a compressor, it is possible to switch to an operating mode with high efficiency and refrigeration capacity across the entire pressure ratio (Pd / Ps) range, and when applying a hybrid type refrigeration cycle that incorporates a compressor into the ejector refrigeration cycle, it is possible to suppress the occurrence of a decrease in refrigeration capacity and system efficiency.

[0038] The first threshold R12 and the second threshold R23, as well as the predetermined threshold temperature Tth, are determined in advance by conducting performance tests on the ejector refrigeration system. The first threshold R12 is, for example, the point at which the efficiency of the ejector 1 alone decreases due to an increase in back pressure, and the second threshold R23 is, for example, the point at which the compressor 7 becomes inoperable due to a decrease in back pressure.

[0039] Furthermore, instead of the pressure ratio (Pd / Ps), the pressure difference (Pd-Ps) may be used as a parameter. Also, instead of the compressor pressure Ps, the pressure between the compressor 7 and the suction inlet 1b may be used. Alternatively, instead of the compressor pressure Ps, the temperature at the inlet side of the evaporator 6, i.e., after expansion by the expansion valve 5, may be used indirectly, and instead of the back pressure Pd, the temperature after condensation by the condenser 2 or the temperature of the cooling water may be used indirectly. Furthermore, instead of the heat source water temperature Tw, the flow rate of the heat source water may be used.

[0040] Furthermore, the check valve 8 may be an on / off valve such as a solenoid valve controlled by the control unit C. However, from a cost perspective, it is preferable to use a check valve 8.

[0041] It should be noted that the configurations illustrated in the above embodiments are functional schematics and do not necessarily have to be physically represented as shown. In other words, the forms of distribution and integration of each device and component are not limited to those shown, and all or part of them can be functionally or physically distributed and integrated in any unit according to various usage situations. [Explanation of Symbols]

[0042] 1 Ejector 1a Drive inlet 1b Suction inlet 1c outlet 2. Condenser 3 pumps 4. Steam generator 5. Expansion valve 6. Evaporator 7 Compressor 8. Check valve 9. Switching mechanism 9a,9b Connection point 20 Heat source C control section E1~E3,EB area M1~M4 curve P1, P2 junction Pd back pressure Ps Compressor Pressure R12 First threshold R23 Second threshold S1 Compressor pressure sensor S2 Back pressure sensor S3 Heat source water temperature sensor Tth predetermined threshold temperature Tw Heat source water temperature V1, V2 Shut-off valves

Claims

1. An ejector refrigeration system comprising: a pump for pressurizing a refrigerant; a steam generator for heating the refrigerant with heat source water supplied from a heat supply source to generate an ejector drive flow; an expansion valve for reducing the pressure of the refrigerant; an evaporator for cooling a medium to be cooled with the refrigerant reduced in pressure by the expansion valve; an ejector for drawing in the refrigerant evaporated by the evaporator with the ejector drive flow of the refrigerant from the steam generator; and a condenser for cooling the refrigerant mixed with the ejector drive flow after being drawn into the ejector, A compressor is positioned between the evaporator and the ejector to compress the refrigerant from the evaporator, A switching mechanism that switches between at least the connection to the suction inlet of the ejector of the compressor and the connection to the discharge port of the ejector of the compressor, A shut-off valve connected in parallel to the compressor, A compressor pressure sensor detects the compressor pressure, which is the refrigerant pressure on the suction side of the compressor. A back pressure sensor detects the back pressure, which is the refrigerant pressure on the discharge side of the ejector. A control unit that, when the pressure ratio of the back pressure to the compressor pressure is less than a first threshold, switches to an ejector mode in which the compressor is turned off and the on-off valve is opened, allowing the refrigerant from the evaporator to flow to the suction inlet of the ejector via the switching mechanism; when the pressure ratio is greater than or equal to the first threshold and less than a second threshold, switches to a parallel hybrid mode in which the compressor is turned on and the on-off valve is opened, allowing the refrigerant from the compressor to flow to the discharge port of the ejector via the switching mechanism; and when the pressure ratio is greater than or equal to the second threshold, switches to a series hybrid mode in which the compressor is turned on and the on-off valve is closed, allowing the refrigerant from the compressor to flow to the suction inlet of the ejector via the switching mechanism. An ejector refrigeration system characterized by comprising the following features.

2. The steam generator is equipped with a heat source water temperature sensor that detects the temperature of the heat source water supplied to the steam generator, The ejector refrigeration apparatus according to claim 1, characterized in that the control unit switches to a compression mode in which, when the temperature of the heat source water is below a predetermined threshold temperature, the compressor is turned on, the pump is turned off, and the on / off valve is closed, thereby allowing the refrigerant from the compressor to flow to the discharge port of the ejector via the switching mechanism.

3. The aforementioned switching mechanism is A first pipe connecting the compressor and the discharge port of the ejector, A second pipe connecting the aforementioned on-off valve and the suction inlet of the ejector, A connecting pipe that connects the earlier first pipe and the earlier second pipe, A first on / off valve is provided between the connection point of the first pipe to which the connecting pipe is connected and the discharge port of the ejector, A second on-off valve is provided in the aforementioned connecting pipe, Equipped with, The ejector refrigeration apparatus according to claim 1, characterized in that the control unit closes the first on-off valve and the second on-off valve in the ejector mode, opens the first on-off valve and closes the second on-off valve in the parallel hybrid mode, and closes the first on-off valve and opens the second on-off valve in the series hybrid mode.

4. The aforementioned switching mechanism is A first pipe connecting the compressor and the discharge port of the ejector, A second pipe connecting the aforementioned on-off valve and the suction inlet of the ejector, A connecting pipe that connects the earlier first pipe and the earlier second pipe, A first on / off valve is provided between the connection point of the first pipe to which the connecting pipe is connected and the discharge port of the ejector, A second on-off valve is provided in the aforementioned connecting pipe, Equipped with, The ejector refrigeration apparatus according to claim 2, characterized in that the control unit closes the first on-off valve and the second on-off valve in the ejector mode, opens the first on-off valve and closes the second on-off valve in the parallel hybrid mode, closes the first on-off valve and opens the second on-off valve in the series hybrid mode, and opens the first on-off valve and closes the second on-off valve in the compression mode.

5. The ejector refrigeration apparatus according to any one of claims 1 to 4, characterized in that the on / off valve is a check valve.

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