JP7604976B2 - Ejector Refrigeration Equipment - Google Patents

Description

The present invention relates to an ejector refrigeration device that has a simple configuration, can shorten the device startup time, and can prevent a decrease in the energy utilization efficiency of an external heat source.

An ejector refrigeration system, for example, as described in Patent Document 1, has already been provided. In this ejector refrigeration system, an ejector is provided between a steam generator as a refrigerant heating means and a condenser in a circulation path through which a refrigerant is circulated, 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 the pump. The branch path includes an expansion valve and an evaporator, and supplies the refrigerant after passing through the evaporator as a suction fluid to the ejector. In this ejector refrigeration system, by supplying a heat source such as waste hot water to the steam generator and supplying water to be cooled to the evaporator, it is possible to obtain cold water cooled in the evaporator.

JP 2014-190587 A

When the heat source supplied to the steam generator is exhaust heat from steam utilization equipment or production lines in a factory for the purpose of energy conservation, the amount of exhaust heat fluctuates depending on the operating conditions of the equipment. When the amount of heat supplied fluctuates in this way, it is possible to ensure a constant supply of heat by providing a large buffer tank, but this would result in the equipment becoming larger.

Here, if a large buffer tank is not provided, the pump that circulates the refrigerant is stopped when the amount of heat supplied from the external device decreases. The pump is located lower than the steam generator and condenser, and is located at the bottom of the device to prevent cavitation at the pump suction port. For this reason, when the pump stops, the refrigerant in the steam generator flows back, and the refrigerant vapor in the condenser condenses and the refrigerant is sucked in, reducing the amount of liquid refrigerant in the steam generator. As a result, when the ejector refrigeration unit is restarted, it takes time to operate the pump and supply refrigerant to the steam generator, which delays the start-up of the ejector refrigeration unit and reduces the energy utilization efficiency of the external heat source.

The present invention has been made in consideration of the above, and aims to provide an ejector refrigeration device with a simple configuration that can shorten the device startup time and prevent a decrease in the energy utilization efficiency of the external heat source.

In order to achieve the above object, the present invention provides an ejector refrigeration system having a pump for pressurizing a liquid refrigerant, a vapor generator for heating the refrigerant with a heat source to generate a driving flow, an expansion valve for reducing the pressure of the liquid 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 driving flow of the refrigerant from the vapor generator, and a condenser for liquefying and cooling the refrigerant mixed with the driving flow after drawing into the ejector, the system being characterized in that the system is provided with an on-off control valve on the refrigerant inlet side and the refrigerant outlet side of the vapor generator, and when the degree of superheat on the refrigerant outlet side of the vapor generator falls below a preset degree of superheat during operation of the system, the system is stopped by performing an operation stop process to stop the pump and close the on-off control valve, and when the operation start conditions are satisfied, the system is started by driving the pump and opening the on-off control valve.

Further, the present invention provides an ejector refrigeration system having a pump for pressurizing a liquid refrigerant, a steam generator for heating the refrigerant with a heat source to generate a driving flow, an expansion valve for reducing the pressure of the liquid refrigerant, an evaporator for cooling a cooled medium with the refrigerant reduced in pressure by the expansion valve, an ejector for sucking in the refrigerant evaporated by the evaporator with the driving flow of refrigerant from the steam generator, and a condenser for liquefying and cooling the refrigerant mixed with the driving flow after being sucked into the ejector, the ejector refrigeration system further comprising a check valve provided on a refrigerant inlet side of the steam generator and an on-off control valve provided on a refrigerant outlet side of the steam generator, and a control unit for stopping the system by performing an operation stop process to stop the pump and close the on-off control valve when a degree of superheat on the refrigerant outlet side of the steam generator falls below a predetermined degree of superheat during operation of the system, and for satisfying an operation start condition, and for driving the pump and opening the on-off control valve to start the system.

The present invention also provides an ejector refrigeration system having a pump for pressurizing a liquid refrigerant, a steam generator for heating the refrigerant with a heat source to generate a driving flow, an expansion valve for reducing the pressure of the liquid 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 driving flow of the refrigerant from the steam generator, and a condenser for liquefying and cooling the refrigerant mixed with the driving flow after drawing into the ejector, the system being characterized in that the system is provided with a check valve on the refrigerant inlet side and the refrigerant outlet side of the steam generator, and that when the degree of superheat on the refrigerant outlet side of the steam generator falls below a preset predetermined degree of superheat during system operation, a control unit is provided for stopping the system by performing an operation stop process for stopping the pump, and when operation start conditions are satisfied, driving the pump to start the system.

The present invention is also characterized in that, in the above invention, the cracking pressure of the check valve provided on the refrigerant outlet side of the steam generator is higher than the cracking pressure of the check valve provided on the refrigerant inlet side of the steam generator.

The present invention is also characterized in that, in the above invention, the operation start condition is that the degree of superheat at the refrigerant outlet side of the steam generator exceeds a predetermined degree of superheat.

The present invention is also characterized in that, in the above invention, a refrigerant temperature sensor is provided for detecting the refrigerant temperature on the refrigerant outlet side of the steam generator, and a refrigerant pressure sensor is provided for detecting the refrigerant pressure on the refrigerant outlet side of the steam generator, and the control unit determines the degree of superheat using the refrigerant temperature detected by the refrigerant temperature sensor and the refrigerant pressure detected by the refrigerant pressure sensor.

The present invention is also characterized in that, in the above invention, the control unit uses a preset refrigerant temperature set value of the refrigerant temperature detected by the refrigerant temperature sensor, or a preset refrigerant pressure set value of the refrigerant pressure detected by the refrigerant pressure sensor, instead of the predetermined degree of superheat of the operation start condition.

The present invention is also characterized in that, in the above invention, a heat source temperature sensor is provided for detecting the heat source temperature of the heat source supplied to the steam generator, and the control unit uses a preset heat source temperature setting value of the heat source temperature detected by the heat source temperature sensor instead of the predetermined degree of superheat of the operation start condition.

The present invention is also characterized in that, in the above invention, the control unit measures the intermittent operation cycle of the heat source in advance, drives the pump a predetermined time before the start of intermittent operation, and if the operation start condition is satisfied, drives the pump to start the device, and if the operation start condition is not satisfied after a certain time has passed, performs operation stop processing including stopping the pump.

In addition, in the above invention, the present invention is characterized in that a refrigerant transfer on-off control valve is provided between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, and when the superheat degree of the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined superheat degree during operation of the device, the control unit closes the expansion valve, continues to drive the pump for a predetermined time, and then closes the refrigerant transfer on-off control valve, stops the pump, and closes the on-off control valve to stop the device.

In addition, in the above invention, the present invention is characterized in that a check valve for refrigerant movement is provided between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, and when the degree of superheat of the refrigerant outlet side of the steam generator falls below a predetermined degree of superheat during operation of the device, the control unit closes the expansion valve, continues to drive the pump for a predetermined time, and then stops the pump and closes the opening/closing control valve to stop the device.

In the above invention, a refrigerant movement on-off control valve is provided between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, and a differential pressure detection unit is provided to detect the differential pressure between the suction port of the pump and the refrigerant outlet of the condenser. When the degree of superheat on the refrigerant outlet side of the steam generator becomes equal to or lower than a preset degree of superheat during operation of the device, the control unit closes the expansion valve and then continues to drive the pump until the head difference corresponding to the differential pressure detected by the differential pressure detection unit becomes greater than the required suction head of the pump. When the head difference becomes greater than the required suction head of the pump, the control unit closes the refrigerant movement on-off control valve, stops the pump, and closes the on-off control valve to stop the device.

In addition, in the above invention, a check valve for refrigerant movement is provided between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, and a differential pressure detection unit is provided to detect the differential pressure between the suction port of the pump and the refrigerant outlet of the condenser, and when the degree of superheat on the refrigerant outlet side of the steam generator falls below a preset level during operation of the device, the control unit closes the expansion valve and then continues to drive the pump until the head difference corresponding to the differential pressure detected by the differential pressure detection unit becomes greater than the required suction head of the pump, and when the head difference becomes greater than the required suction head of the pump, the control unit stops the pump and closes the opening/closing control valve to stop the device.

In addition, in the above invention, the present invention provides a refrigerant movement on-off control valve between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, and a differential pressure detection unit that detects the differential pressure between the suction port of the pump and the refrigerant outlet of the condenser, and when the degree of superheat on the refrigerant outlet side of the steam generator falls below a preset level during operation of the device, the control unit closes the expansion valve and then continues to drive the pump until the head difference corresponding to the differential pressure detected by the differential pressure detection unit becomes greater than the required suction head of the pump, and when the head difference becomes greater than the required suction head of the pump, the control unit closes the refrigerant movement on-off control valve and performs an operation stop process to stop the pump and stop the device.

In addition, in the above invention, the present invention provides a check valve for refrigerant movement between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, and a differential pressure detection unit for detecting the differential pressure between the suction port of the pump and the refrigerant outlet of the condenser, and when the degree of superheat on the refrigerant outlet side of the steam generator falls below a preset level during operation of the device, the control unit closes the expansion valve and then continues to drive the pump until the head difference corresponding to the differential pressure detected by the differential pressure detection unit becomes greater than the required suction head of the pump, and when the head difference becomes greater than the required suction head of the pump, the control unit performs an operation stop process to stop the pump and stop the device.

The present invention further comprises, in the above invention, a storage tank provided downstream of the condenser for storing the refrigerant condensed by the condenser, a first on-off control valve provided between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, and a second on-off control valve provided between the discharge port of the ejector and the refrigerant inlet of the condenser, and the control unit is characterized in that when the degree of superheat of the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the device, the control unit closes the expansion valve, and then continues to drive the pump for a predetermined time, and then closes the first on-off control valve, closes the second on-off control valve, stops the pump, and closes the on-off control valve to stop the device.

The present invention is also characterized in that, in the above invention, a liquid level detection sensor is provided for detecting the liquid level in the storage tank, and when the degree of superheat on the refrigerant outlet side of the steam generator falls below a preset predetermined degree of superheat during operation of the device, the control unit closes the expansion valve and then continues to drive the pump until the head difference from the position of the pump to the liquid level position detected by the liquid level detection sensor becomes greater than the required suction head of the pump, and then closes the first opening/closing control valve and further closes the second opening/closing control valve to stop the pump and close the opening/closing control valve to stop the device.

The present invention further includes, in the above invention, a storage tank provided downstream of the condenser for storing the refrigerant condensed by the condenser, a first on-off control valve provided between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, and a second on-off control valve provided between the discharge port of the ejector and the refrigerant inlet of the condenser, and the control unit is characterized in that when the degree of superheat of the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the device, the control unit closes the expansion valve, and then continues to drive the pump for a predetermined time, and then closes the first on-off control valve, further closes the second on-off control valve, and performs an operation stop process to stop the pump and stop the device.

The present invention is also characterized in that, in the above invention, a liquid level detection sensor is provided for detecting the liquid level in the storage tank, and when the degree of superheat at the refrigerant outlet side of the steam generator falls below a preset predetermined degree of superheat during operation of the device, the control unit closes the expansion valve and then continues to drive the pump until the head difference from the position of the pump to the liquid level position detected by the liquid level detection sensor becomes greater than the required suction head of the pump, and then closes the first opening/closing control valve, further closes the second opening/closing control valve, and performs an operation stop process to stop the pump and stop the device.

In addition, the present invention, in the above invention, includes a storage tank provided downstream of the condenser to store the refrigerant condensed by the condenser, a first opening/closing control valve provided between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, a second opening/closing control valve provided between the discharge port of the ejector and the refrigerant inlet of the condenser, a pipe connecting the expansion valve and the evaporator, a storage tank connection pipe connecting the pipe connecting the condenser and the storage tank, and a third opening/closing control valve provided in the storage tank connection pipe, and the control unit is characterized in that when the superheat degree of the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined superheat degree during operation of the device, the control unit closes the expansion valve, then closes the second opening/closing control valve and opens the third opening/closing control valve, continues to drive the pump for a predetermined time, and then closes the first opening/closing control valve and the third opening/closing control valve to stop the pump, and further closes the opening/closing control valve to perform an operation stop process to stop the device.

The present invention further includes, in the above invention, a storage tank provided downstream of the condenser for storing the refrigerant condensed by the condenser, a first on-off control valve provided between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, a second on-off control valve provided between the discharge port of the ejector and the refrigerant inlet of the condenser, a pipe connecting the expansion valve and the evaporator, a storage tank connection pipe connecting the pipe connecting the condenser and the storage tank, and a third on-off control valve provided in the storage tank connection pipe, and the control unit is characterized in that when the superheat degree of the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined superheat degree during operation of the device, the control unit closes the expansion valve, closes the second on-off control valve and opens the third on-off control valve, continues to drive the pump for a predetermined time, and then closes the first on-off control valve and closes the third on-off control valve, and performs an operation stop process to stop the pump and stop the device.

The present invention is also characterized in that, in the above invention, a liquid level detection sensor is provided for detecting the liquid level in the storage tank, and when the degree of superheat at the refrigerant outlet side of the steam generator falls below a preset predetermined degree of superheat during operation of the device, the control unit closes the expansion valve, then closes the second opening/closing control valve and opens the third opening/closing control valve, and continues to drive the pump until the head difference from the position of the pump to the liquid level position detected by the liquid level detection sensor becomes greater than the required suction head of the pump, and then closes the first opening/closing control valve and closes the third opening/closing control valve, and performs an operation stop process to stop the pump and stop the device.

The present invention further includes, in the above invention, a storage tank provided downstream of the condenser for storing the refrigerant condensed by the condenser, a first on-off control valve provided between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, a second on-off control valve provided between the discharge port of the ejector and the refrigerant inlet of the condenser, a pipe connecting the expansion valve and the evaporator, a condenser connection pipe connecting the pipe connecting the second on-off control valve and the condenser, and a fourth on-off control valve provided in the condenser connection pipe, and the control unit is characterized in that, when the degree of superheat of the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the device, the control unit closes the expansion valve, closes the second on-off control valve and opens the fourth on-off control valve, continues to drive the pump for a predetermined time, and then closes the first on-off control valve and closes the fourth on-off control valve to stop the pump, and further closes the on-off control valve to stop the device.

The present invention is also characterized in that, in the above invention, a liquid level detection sensor is provided for detecting the liquid level in the storage tank, and when the degree of superheat at the refrigerant outlet side of the steam generator falls below a preset predetermined degree of superheat during operation of the device, the control unit closes the expansion valve, then closes the second opening/closing control valve and opens the fourth opening/closing control valve, and continues to drive the pump until the head difference from the position of the pump to the liquid level position detected by the liquid level detection sensor becomes greater than the required suction head of the pump, and then closes the first opening/closing control valve and the fourth opening/closing control valve to stop the pump, and further performs an operation stop process to close the opening/closing control valve to stop the device.

The present invention further includes, in the above invention, a storage tank provided downstream of the condenser for storing the refrigerant condensed by the condenser, a first on-off control valve provided between the refrigerant outlet side of the evaporator and the refrigerant suction port of the ejector, a second on-off control valve provided between the discharge port of the ejector and the refrigerant inlet of the condenser, a pipe connecting the expansion valve and the evaporator, a condenser connection pipe connecting the pipe connecting the second on-off control valve and the condenser, and a fourth on-off control valve provided in the condenser connection pipe, and the control unit is characterized in that when the superheat degree of the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined superheat degree during operation of the device, the control unit closes the expansion valve, closes the second on-off control valve and opens the fourth on-off control valve, continues to drive the pump for a predetermined time, and then closes the first on-off control valve and closes the fourth on-off control valve, and performs an operation stop process to stop the pump and stop the device.

The present invention is also characterized in that, in the above invention, a liquid level detection sensor is provided for detecting the liquid level in the storage tank, and when the degree of superheat at the refrigerant outlet side of the steam generator falls below a preset predetermined degree of superheat during operation of the device, the control unit closes the expansion valve, then closes the second opening/closing control valve and opens the fourth opening/closing control valve, and continues to drive the pump until the head difference from the position of the pump to the liquid level position detected by the liquid level detection sensor becomes greater than the required suction head of the pump, and then closes the first opening/closing control valve and closes the fourth opening/closing control valve, and performs an operation stop process to stop the pump and stop the device.

The present invention is also characterized in that, in the above invention, the pump is located below the lower end of the storage tank, and the pipe connecting the storage tank and the pump is inclined toward the suction port of the pump over the entire area from the refrigerant outlet of the storage tank to the suction port of the pump.

The present invention is also characterized in that, in the above invention, the refrigerant outlet of the condenser or the refrigerant outlet of the storage tank located downstream of the condenser is located vertically above the refrigerant outlet of the steam generator.

The present invention has a simple configuration that can shorten the device startup time and prevent a decrease in the energy utilization efficiency of the external heat source.

FIG. 1 is a circuit diagram showing the configuration of an ejector refrigeration system according to an embodiment of the present invention. FIG. 2 is a flowchart showing a procedure for controlling the stop and start of the ejector refrigeration apparatus shown in FIG. 1 by the control unit. FIG. 3 is a circuit diagram showing the configuration of an ejector refrigeration system according to the first modification. FIG. 4 is a flowchart showing a procedure of the stop/start control process of the device performed by the control unit of the first modified example. FIG. 5 is a circuit diagram showing the configuration of an ejector refrigeration system according to the second modification. FIG. 6 is a flowchart showing a procedure of the stop/start control process of the device performed by the control unit in the third modification. FIG. 7 is a circuit diagram showing the configuration of an ejector refrigeration system according to a second embodiment of the present invention. FIG. 8 is a flowchart showing a procedure for shutting down the operation of the ejector refrigeration apparatus shown in FIG. FIG. 9 is a circuit diagram showing the configuration of an ejector refrigeration system according to the fourth modification. FIG. 10 is a circuit diagram showing the configuration of an ejector refrigeration system according to the fifth modification. FIG. 11 is a flowchart showing a procedure of a process for stopping operation by the control unit of the ejector refrigeration unit shown in FIG. FIG. 12 is a circuit diagram showing the configuration of an ejector refrigeration system according to a third embodiment of the present invention. FIG. 13 is a flowchart showing a procedure of a process for stopping operation by the control unit of the ejector refrigeration unit shown in FIG. FIG. 14 is a circuit diagram showing the configuration of an ejector refrigeration system according to the sixth modification. FIG. 15 is a flowchart showing a procedure of a process for stopping operation by the control unit of the ejector refrigeration unit shown in FIG. FIG. 16 is a circuit diagram showing the configuration of an ejector refrigeration system according to the seventh modification. FIG. 17 is a circuit diagram showing the configuration of an ejector refrigeration system according to the eighth modification. FIG. 18 is a flowchart showing a procedure of a process for stopping operation by the control unit of the ejector refrigeration unit shown in FIG. FIG. 19 is a circuit diagram showing the configuration of an ejector refrigeration system according to the ninth modification. FIG. 20 is a flowchart showing a procedure for shutting down the operation of the ejector refrigeration unit shown in FIG. 19 by the control unit. FIG. 21 is a circuit diagram showing the configuration of an ejector refrigeration system according to a fourth embodiment of the present invention. FIG. 22 is a schematic diagram showing the state of the liquid phase refrigerant when the ejector refrigeration unit stops operating and heat exchange in the steam generator is insufficient. FIG. 23 is a schematic diagram showing the state of the liquid phase refrigerant when the ejector refrigeration unit starts operating and heat exchange in the steam generator is insufficient. FIG. 24 is a flowchart showing an operation control process procedure by the control unit of the ejector refrigeration unit shown in FIG.

The following describes the embodiment of the invention with reference to the attached drawings.

[First embodiment]
FIG. 1 is a circuit diagram showing the configuration of an ejector refrigeration system 11 according to a first embodiment of the present invention. The ejector refrigeration system 11 illustrated here recovers exhaust heat from waste hot water such as factory wastewater or used cooling water to cool a medium to be cooled, and has an ejector 1, a condenser 2, a pump 3, and a steam generator 4 connected in sequence on a circulation path L1. The ejector refrigeration system 11 is also provided with a branch path L2. The branch path L2 branches off from a portion upstream of the pump 3 between the condenser 2 and the steam generator 4 of the circulation path L1, and supplies a part of the refrigerant flowing through the circulation path L1 to the ejector 1 as a suction fluid. The medium to be cooled may be water, oil, or other refrigerants. In this first embodiment, an ejector refrigeration system that generates cold water from the water to be cooled by using exhaust heat recovered from the waste hot water is illustrated.

The pump 3 circulates and supplies the refrigerant in the circulation path L1. More specifically, the pump 3 is, for example, a liquid-phase variable displacement pump, which pressurizes the refrigerant and supplies it to the ejector 1. The pump 3 in this embodiment 1 is driven at a rotation speed according to a drive signal given from the control unit C1 described later. The steam generator 4 evaporates the refrigerant supplied from the pump 3 by exchanging heat with a heat source such as exhaust hot water supplied to the steam generator 4. The ejector 1 sucks, mixes, and pressurizes the gas-phase refrigerant supplied from the evaporator 6 by a driving flow that is the gas-phase refrigerant that has passed through the steam generator 4, and discharges it downstream. The condenser 2 condenses the refrigerant in the circulation path L1 by exchanging heat between the gas-phase refrigerant discharged from the ejector 1 and the cooling water supplied to the condenser 2 and dissipating heat.

An expansion valve 5 and an evaporator 6 are provided in the branch path L2. The expansion valve 5 expands and reduces the pressure of the refrigerant that has passed through the condenser 2 and is supplied through the condenser. The evaporator 6 evaporates the refrigerant by exchanging heat between the liquid-phase or two-phase gas-liquid refrigerant that has passed through the expansion valve 5 and the cooled water that is supplied to the evaporator 6. Note that an electronic expansion valve is preferable as the expansion valve 5, but other types of expansion valves such as a manual expansion valve, a constant pressure expansion valve, or a temperature expansion valve may be appropriately selected depending on the application and configuration.

An on-off control valve 20 is provided on the refrigerant inlet side of the steam generator 4. An on-off control valve 21 is provided on the refrigerant outlet side of the steam generator 4. The on-off control valve 20 is, for example, a solenoid valve, and is provided between the discharge port of the pump 3 and the refrigerant inlet of the steam generator 4. The on-off control valve 21 is, for example, a solenoid valve, and is provided between the refrigerant outlet of the steam generator 4 and the ejector 1.

A refrigerant temperature sensor 22 that detects the refrigerant temperature T1 on the outlet side of the steam generator 4, and a refrigerant pressure sensor 23 that detects the refrigerant pressure P1 are provided between the steam generator 4 and the on-off control valve 21. In addition, there is a heat source temperature sensor 24 that detects the heat source temperature T2 of the heat source supplied to the steam generator 4.

The control unit C1 controls the pump 3 and the expansion valve 5 based on the refrigerant temperature T1, refrigerant pressure P1, and heat source temperature T2 obtained from the refrigerant temperature sensor 22, the refrigerant pressure sensor 23, and the heat source temperature sensor 24, respectively.

When the degree of superheat on the refrigerant outlet side of the steam generator 4 falls below a preset predetermined degree of superheat during operation of the device, the control unit C1 performs an operation stop process to stop the device by stopping the pump 3 and closing the on-off control valves 20 and 21, and when the operation start condition is satisfied, the control unit C1 drives the pump 3 and opens the on-off control valves 20 and 21 to start the device. The operation start condition is that the degree of superheat on the refrigerant outlet side of the steam generator 4 exceeds a predetermined degree of superheat. The degree of superheat is calculated using the refrigerant temperature T1 and the refrigerant pressure P1. The degree of superheat is the degree of temperature rise when the gas becomes higher than the saturation temperature of the gas under a certain pressure, and the predetermined degree of superheat is, for example, 0 (K).

The operation start condition is not limited to a predetermined degree of superheat, and may be a preset refrigerant temperature set value of the refrigerant temperature T1 detected by the refrigerant temperature sensor 22, a preset refrigerant pressure set value of the refrigerant pressure detected by the refrigerant pressure sensor 23, or a preset heat source temperature set value of the heat source temperature T2 detected by the heat source temperature sensor 24. The operation start condition is a condition for the ejector refrigeration device 11 to reach a state in which it can operate, specifically, a pressure state in which the ejector 1 can be driven. In this embodiment, whether the amount of heat of the heat source is sufficient to start or maintain operation is determined based on the heat source temperature T2, but the amount of heat may be determined not only based on the heat source temperature T2 but also by determining the flow rate of the heat source using a flow rate sensor or the like to determine whether the amount of heat is sufficient.

In this embodiment 1, when the amount of heat from the heat source supplied from the outside is not sufficient to maintain operation, the pump 3 is stopped and the on-off control valves 20 and 21 are closed to perform the operation stop process. Therefore, the refrigerant in the steam generator 4 does not flow back, and even if refrigerant vapor condenses in the condenser 2 and refrigerant is sucked in, the amount of liquid refrigerant in the steam generator 4 does not decrease. As a result, when the ejector refrigeration device 11 is restarted, the time required to operate the pump 3 and supply refrigerant to the steam generator 4 is shortened, allowing for rapid restart, and since there is no delay in starting the ejector refrigeration device 11, the energy utilization efficiency of the external heat source does not decrease.

<Stop/Start Control>
2 is a flowchart showing the procedure of the control unit C1 of the ejector refrigeration device 11 shown in FIG. 1 to stop and start the device. First, the control unit C1 determines whether the ejector refrigeration device 11 itself is in operation (step S110). If the ejector refrigeration device 11 is in operation (step S110: Yes), the control unit C1 acquires the refrigerant temperature T1, the refrigerant pressure P1, and the heat source temperature T2 measured by the refrigerant temperature sensor 22, the refrigerant pressure sensor 23, and the heat source temperature sensor 24, respectively (step S120). Then, the control unit C1 determines whether the heat source has stopped (step S130). Here, whether the heat source has stopped is determined by whether the heat source temperature T2 is equal to or lower than the heat source temperature setting value. If the heat source has not stopped (step S130: No), the process proceeds to step S120, and the measurements of the refrigerant temperature T1, the refrigerant pressure P1, and the heat source temperature T2 are repeated.

On the other hand, if the heat source is stopped (step S130: Yes), the degree of superheat is calculated (step S140). This degree of superheat is calculated using the refrigerant temperature T1 and the refrigerant pressure P1. Then, the control unit C1 determines whether the degree of superheat is equal to or lower than a predetermined degree of superheat (step S150). If the degree of superheat is not equal to or lower than the predetermined degree of superheat (step S150: No), the process proceeds to step S120.

If the degree of superheat is equal to or lower than the predetermined degree of superheat (step S150: Yes), operation cannot be maintained, so the device is shut down (step S160). In this shutdown process, the pump 3 is stopped and the on-off control valves 20 and 21 are closed. The control unit C1 then shuts down the ejector refrigeration device 11 (step S180) and ends this process.

On the other hand, if the ejector refrigeration unit 11 is not in operation (step S110: No), the refrigerant temperature T1, refrigerant pressure P1, and heat source temperature T2 measured by the refrigerant temperature sensor 22, refrigerant pressure sensor 23, and heat source temperature sensor 24, respectively, are acquired (step S190). However, in this embodiment, since the degree of superheat is not used as the operation start condition, but the refrigerant pressure set value is used, it is sufficient to acquire only the refrigerant pressure P1.

Then, the control unit C1 determines whether the refrigerant pressure P1 exceeds the refrigerant pressure set value (step S200). If the refrigerant pressure P1 does not exceed the refrigerant pressure set value (step S200: No), the control unit C1 proceeds to step S190 and measures the refrigerant pressure P1.

On the other hand, if the refrigerant pressure P1 exceeds the refrigerant pressure set value (step S200: Yes), the operation start condition is satisfied, and the operation start process of the device is performed (step S210). In this operation start process, the pump 3 is operated and the on-off control valves 20 and 21 are opened. After that, the ejector refrigeration device 11 is started up (step S230), and this process ends. The above process is repeated at predetermined time intervals.

<Modification 1>
3 is a circuit diagram showing the configuration of an ejector refrigeration system 12 according to Modification 1. This ejector refrigeration system 12 has check valves 30 and 31 arranged in place of the on-off control valves 20 and 21 of the ejector refrigeration system 11. The other configurations are the same as those of Embodiment 1. The check valves 30 and 31 each allow the refrigerant to flow in the flow direction of the circulation path L1 and prevent the refrigerant from flowing in the reverse direction.

Here, the check valve 30 prevents the liquid refrigerant in the steam generator 4 from flowing back when the pump 3 is stopped. On the other hand, the check valve 31 is required to prevent the refrigerant from liquefying in the condenser 2 after the pump 3 is stopped, and from vaporizing and flowing out of the steam generator 4 as a result of this liquefaction. For this reason, the cracking pressure of the check valve 31 is set higher than the cracking pressure of the check valve 30 provided on the refrigerant inlet side of the steam generator 4, so as to minimize the outflow of the refrigerant. The cracking pressure of the check valve 31 can be increased, for example, by using a spring or the like.

In this modified example 1, check valves 30, 31 are used instead of the opening/closing control valves 20, 21, which allows for cost reduction compared to embodiment 1 and eliminates the need for valve control. In addition, the check valves 30, 31 do not seal the steam generator 4, so there is no need to provide a relief valve or the like, resulting in a simplified configuration.

Figure 4 is a flowchart showing the procedure for the device stop/start control process performed by the control unit C2 in Modification 1. Note that steps S310 to S350 are the same as steps S110 to S150.

If the degree of superheat is equal to or lower than the predetermined degree of superheat (step S350: Yes), the control unit C2 performs a process to stop the operation of the device (step S360) since operation cannot be maintained. In this process, the pump 3 is stopped. Then, the ejector refrigeration device 12 is stopped (step S370), and this process ends.

On the other hand, if the ejector refrigeration unit 12 is not in operation (step S310: No), the refrigerant temperature T1, refrigerant pressure P1, and heat source temperature T2 measured by the refrigerant temperature sensor 22, refrigerant pressure sensor 23, and heat source temperature sensor 24, respectively, are acquired (step S380). However, in this modified example 1, the degree of superheat is not used as the operation start condition, but the heat source temperature set value is used, so it is sufficient to acquire only the heat source temperature T2.

Then, the control unit C2 determines whether the heat source temperature T2 exceeds the refrigerant temperature set value (step S390). If the heat source temperature T2 does not exceed the heat source temperature set value (step S390: No), the control unit C2 proceeds to step S380 and measures the heat source temperature T2.

On the other hand, if the heat source temperature T2 exceeds the heat source temperature set value (step S390: Yes), the operation start condition is satisfied, and operation start processing is performed (step S400). In this operation start processing, the pump 3 is operated. After that, the ejector refrigeration device 11 is started up (step S410), and this processing ends. The above processing is repeated at predetermined time intervals.

<Modification 2>
Fig. 5 is a circuit diagram showing the configuration of an ejector refrigeration system 13 according to the second modification. In this ejector refrigeration system 13, a check valve 40 is provided instead of the on-off control valve 20 of the ejector refrigeration system 11, and an on-off control valve 41 corresponding to the on-off control valve 21 is provided. The other configurations are the same as those of the embodiment. In the stop start control process procedure by the control unit C3, valve control of only the on-off control valve 41 is performed in steps S160 and S220 in Fig. 2. By providing this on-off control valve 41, it is possible to prevent the refrigerant from evaporating and flowing out of the steam generator 4 when the pump is stopped.

<Modification 3>
The ejector refrigeration apparatus 13 of the present modified example 3 is the same as the ejector refrigeration apparatus 12 of the modified example 2, but the control process of the control unit is different. In the present modified example 3, the intermittent operation cycle of the heat source is measured in advance, and an operation start process is performed to drive the pump 3 a predetermined time before the start of the intermittent operation, and if the operation start conditions are satisfied, the apparatus is started while maintaining the drive of the pump 3, and if the operation start conditions are not satisfied even after the lapse of a certain time, an operation stop process is performed to stop the pump.

Figure 6 is a flowchart showing the procedure for the device stop/start control process performed by the control unit C3 in the third modified example. Note that steps S510 to S570 are the same as steps S310 to S370. First, the control unit C3 measures and determines the intermittent operation period of the heat source by continuously measuring the heat source temperature T2 as a premise.

As shown in FIG. 6, when the ejector refrigeration device 13 is not in operation (step S580: No), the control unit C3 determines whether or not it is a predetermined cycle time ΔT before the intermittent operation cycle of the heat source based on the intermittent operation cycle of the heat source (step S580). Here, if the start of intermittent operation is predicted to be time ts, the time before the start of intermittent operation is the time (ts-ΔT).

If the predetermined periodic time ΔT of the intermittent operation cycle of the heat source has not yet arrived (step S580: No), the process proceeds to step S510. On the other hand, if the predetermined periodic time ΔT of the intermittent operation cycle of the heat source has yet to arrive (step S580: Yes), the process performs operation start processing in anticipation of the start of operation (step S590). In this operation start processing, the pump 3 is operated.

Then, the control unit C3 acquires the refrigerant temperature T1, the refrigerant pressure P1, and the heat source temperature T2 measured by the refrigerant temperature sensor 22, the refrigerant pressure sensor 23, and the heat source temperature sensor 24, respectively (step S600). However, in this modification example 3, since the degree of superheat is not used as the operation start condition, but the heat source temperature setting value is used, it is sufficient to acquire only the heat source temperature T2.

Then, the control unit C3 determines whether the heat source temperature T2 exceeds the refrigerant temperature set value (step S610). If the heat source temperature T2 exceeds the heat source temperature set value (step S610: Yes), the control unit C3 starts the ejector refrigeration device 12 (step S620) while maintaining the operation of the pump 3, and ends this process.

On the other hand, if the heat source temperature T2 does not exceed the heat source temperature setting value (step S610: No), it is further determined whether or not a certain time has elapsed since the start of operation of the pump 3 (step S630). If the certain time has not elapsed (step S630: No), the process proceeds to step S600, and if the certain time has elapsed (step S630: Yes), an operation stop process is performed to stop the pump 3 (step S640), and this process ends. The above process is repeated at predetermined time intervals.

In this third modification, when the intermittent operation cycle of the heat source can be obtained, the start time of intermittent operation is predicted and the pump 3 is operated in advance. Therefore, since refrigerant is sent into the steam generator 4 at the start of operation, a rapid restart can be performed, and since there is no delay in starting the ejector refrigeration device 12, the energy utilization efficiency of the external heat source is not reduced.

[Embodiment 2]
Incidentally, when the ejector cooling device is in operation, the steam generator 4 and the evaporator 6 undergo continuous phase changes from liquid to gaseous in the heat exchangers due to heat absorption, and from gaseous to liquid in the condenser 2. Here, after the device is stopped, a temperature difference occurs in the circuit due to heat remaining in the components of the circuit, mainly in components with large heat capacity such as the heat exchanger, and a large amount of refrigerant condenses and accumulates in the evaporator 6, which has the lowest temperature. Specifically, the temperatures of the heat exchangers when the device is stopped are 60°C to 80°C for the steam generator 4, 5°C to 20°C for the evaporator 6, and 15°C to 30°C for the condenser 2. The temperature of the evaporator 6 is the lowest, and the refrigerant is likely to condense and accumulate. As a result, if the amount of refrigerant to be held in the condenser 2 decreases, the required suction head will be insufficient when the pump 3 is started, and cavitation will occur, which will lead to the failure of the pump 3. Therefore, in the second embodiment, the refrigerant in the evaporator 6 is moved to the condenser 2 side so that the required suction head of the pump 3 can be secured when the device is stopped, thereby preventing the occurrence of cavitation when the pump 3 is started.

Figure 7 is a circuit diagram showing the configuration of an ejector refrigeration system 51 according to a second embodiment of the present invention. The ejector refrigeration system 51 has a refrigerant transfer on-off control valve V1 on a branch path L2 between the refrigerant outlet side of the evaporator 6 of the ejector refrigeration system 51 and the refrigerant suction port of the ejector 1.

When the degree of superheat at the refrigerant outlet side of the steam generator 4 falls below a preset level during operation of the device, the control unit C51 closes the expansion valve 5, continues to drive the pump 3 for a preset time, and moves the refrigerant in the evaporator 6 to the condenser 2 side by the suction action of the ejector 1, and then closes (fully closes) the refrigerant movement on-off control valve V1 to prevent backflow of the moved refrigerant, stops the pump 3, and closes the on-off control valves 20 and 21 to stop the device. By driving the pump 3 for the preset time, a refrigerant recovery flow path R1 is formed from the evaporator 6 to the condenser 2, and the refrigerant in the evaporator 6 moves to the condenser 2 side.

Here, a pressure equivalent to the head difference (effective suction head NPSHA) between the suction port of pump 3 and the average liquid level in condenser 2 is applied to the suction port of pump 3. In general, cavitation is prevented by operating pump 3 under conditions where the effective suction head NPSHA is greater than the required suction head NPSHR. Note that the required suction head NPSHR depends on the suction capacity of pump 3, and the effective suction head NPSHA depends on the height position of condenser 2 relative to pump 3. Therefore, the specified time is the time for storing an amount of refrigerant in condenser 2 that results in a head difference greater than the required suction head NPSHR, and is determined and set in advance by experiment, etc.

In addition, since the pressure loss of the suction flow caused by the placement of the refrigerant transfer on-off control valve V1 directly affects the cooling capacity, it is preferable to make the inner diameter of the valve section approximately the same as the piping diameter of the branch path L2 to minimize the pressure loss.

<Operation shutdown process>
FIG. 8 is a flow chart showing the operation stop processing procedure by the control unit C51 of the ejector refrigeration device 51 shown in FIG. 7. This operation stop processing is a subroutine corresponding to the operation stop processing (step S160) shown in FIG. 2. First, the control unit C51 closes the expansion valve 5 (fully closed) (step S710). Then, after the expansion valve 5 is closed, it is determined whether or not a predetermined time has elapsed (step S720). If the predetermined time has not elapsed (step S720: No), this determination processing is repeated. Until this predetermined time has elapsed, the refrigerant transfer opening/closing control valve V1 is open, and the refrigerant in the evaporator 6 moves to the condenser 2 side through the refrigerant recovery passage R1 due to the suction action of the ejector 1.

On the other hand, if the predetermined time has elapsed (step S720: Yes), the refrigerant transfer on-off control valve V1 is closed (step S730) and the pump 3 is stopped (step S740). After that, the control unit C51 closes the on-off control valves 20 and 21 (step S750) and returns to step S180.

<Modification 4>
9 is a circuit diagram showing the configuration of an ejector refrigeration system 52 according to the fourth modification. In the second embodiment, the refrigerant transfer on-off control valve V1 that functions as an on-off control valve is provided, but in the fourth modification, a refrigerant transfer check valve VB1 that functions as a check valve is provided instead of the refrigerant transfer on-off control valve V1. The refrigerant transfer check valve VB1 allows the refrigerant to flow in the flow direction from the evaporator 6 side to the ejector 1 in the branch path L2, and prevents the refrigerant from flowing in the reverse direction. The refrigerant transfer check valve VB1 does not require control by the controller C52, and therefore the control is simplified.

That is, when the degree of superheat on the refrigerant outlet side of the steam generator 4 falls below a preset predetermined degree of superheat during operation of the device, the control unit C52 closes the expansion valve 5, continues to drive the pump 3 for a predetermined time, and then stops the pump 3 and closes the on-off control valves 20 and 21 to stop the device. This operation stop process is a subroutine that corresponds to the operation control process of step 160, as in the second embodiment.

When the device is operating, the refrigerant transfer check valve VB1 may become a flow path resistance. Therefore, it is necessary to design the flow path resistance to be sufficiently small relative to the amount of pressure rise of the ejector 1 (= ejector discharge pressure - ejector suction port pressure).

<Modification 5>
Fig. 10 is a circuit diagram showing the configuration of an ejector refrigeration unit 53 according to Modification 5. In the above-mentioned embodiment 2 and Modification 4, the operation stop process is performed by closing the expansion valve 5 and then continuing to drive the pump 3 for a preset time period, but in Modification 5, a differential pressure sensor PD is provided that functions as a differential pressure detection unit that detects a differential pressure ΔP between the suction port PT2 of the pump 3 and the refrigerant outlet PT1 of the condenser.

Then, the control unit C53 continues to drive the pump 3 for a predetermined time until the head difference h corresponding to the differential pressure ΔP detected by the differential pressure sensor PD becomes greater than the required suction head NPSHR of the pump 3.

<Operation shutdown process>
Fig. 11 is a flow chart showing the procedure of the operation stop process by the control unit C53 of the ejector refrigeration unit 53 shown in Fig. 10. This operation stop process is a subroutine corresponding to the operation stop process (step S160) shown in Fig. 2. First, the control unit C53 closes (fully closes) the expansion valve 5 (step S810). Then, it is determined whether or not the head difference h calculated from the differential pressure ΔP detected by the differential pressure sensor PD is larger than the required suction head NPSHR (step S820).

If the head difference h is greater than the required suction head NPSHR (step S820: Yes), the amount of refrigerant stored in the condenser 2 is sufficient, and the refrigerant transfer on-off control valve V1 is switched from open to closed (step S830), and the pump 3 is stopped (step S840). After that, the control unit C53 closes the on-off control valves 20 and 21 (step S850), and returns to step S180.

On the other hand, if the head difference h is not greater than the required suction head NPSHR (step S820: No), it is determined whether a certain time has elapsed (step S860). This certain time is, for example, a time exceeding a predetermined time, and if the certain time has elapsed, it is the time during which a sufficient amount of refrigerant is stored in the condenser 2 unless there is an abnormality in the device.

If the fixed time has not elapsed (step S860: No), the process proceeds to step S820, the pump 3 continues to be driven, and the determination process of step S820 is performed. On the other hand, if the fixed time has elapsed (step S860: Yes), it is possible that there is an abnormality in the device, so an alarm is notified to an alarm device outside the device (step S870), and the process returns to step S180.

By using this differential pressure ΔP to determine the amount of refrigerant in the condenser 2, cavitation of the pump 3 can be reliably prevented, and the operating time of the pump 3 during the operation shutdown process can be set to an appropriate time.

When applying the second embodiment and the fourth and fifth variations to the second and third variations, the above-mentioned operation stop process becomes a subroutine corresponding to steps S360, S560, and S640.

A storage tank for storing the refrigerant condensed by the condenser 2 may also be provided downstream of the condenser 2. In this case, the refrigerant moving from the evaporator 6 is stored in the storage tank.

[Embodiment 3]
In the same manner as in embodiment 2, this embodiment 3 aims to move the refrigerant to the condenser 2 side when the device is stopped, thereby ensuring the necessary suction head of the pump 3 and preventing the occurrence of cavitation when the pump 3 is started.

Figure 12 is a circuit diagram showing the configuration of an ejector refrigeration system 61 according to the third embodiment of the present invention. The ejector refrigeration system 61 further includes a storage tank 7, a first on-off control valve V11, and a second on-off control valve V12 in addition to the ejector refrigeration system 11 according to the first embodiment. The storage tank 7 is provided downstream of the condenser 2 and stores the refrigerant condensed by the condenser. The first on-off control valve V11 is provided between the refrigerant outlet side of the evaporator 6 and the refrigerant suction port of the ejector 1, similar to the refrigerant transfer on-off control valve V1. The second on-off control valve V12 is provided between the discharge port of the ejector 1 and the refrigerant inlet of the condenser 2.

When the degree of superheat at the refrigerant outlet side of the steam generator 4 falls below a preset predetermined degree of superheat during operation of the device, the control unit C61 closes the expansion valve 5 (fully closed) and continues to drive the pump 3 for a predetermined time, and then closes the first on-off control valve V11 and the second on-off control valve V12 to stop the pump 3 and close the on-off control valves 20 and 21 to stop the device. By driving the pump 3 for the predetermined time, the circulation path L1 functions as a refrigerant recovery flow path R11 to the condenser 2, and the refrigerant is stored in the storage tank 7 via the condenser 2.

As in the second embodiment, this predetermined time is the time for storing an amount of refrigerant in the storage tank 7 such that the head difference is greater than the required suction head NPSHR. This predetermined time can be estimated from the average flow velocity in the refrigerant recovery flow path R11 and the flow path length of the refrigerant recovery flow path R11, but it may also be determined by experiment.

<Operation shutdown process>
Fig. 13 is a flow chart showing the procedure of the operation stop process by the control unit C61 of the ejector refrigeration unit 61 shown in Fig. 12. This operation stop process is a subroutine corresponding to the operation stop process (step S160) shown in Fig. 2. First, the control unit C61 closes (fully closes) the expansion valve 5 (step S910). This forms the refrigerant recovery passage R11.

Then, after the expansion valve 5 is closed, it is determined whether or not a predetermined time has elapsed (step S920). If the predetermined time has not elapsed (step S920: No), this determination process is repeated. Until this predetermined time has elapsed, the first opening/closing control valve V11 is open, but the refrigerant moves to the storage tank 7 due to the movement of the refrigerant through the refrigerant recovery flow path R11.

On the other hand, if the predetermined time has elapsed (step S920: Yes), the first on-off control valve V11 is closed (step S930), the second on-off control valve V12 is closed (step S940), and the pump 3 is stopped (step S950). After that, the control unit C61 closes the on-off control valves 20 and 21 (step S960) and returns to step S180.

In addition, unlike embodiment 2, in this embodiment 3, even if a heat source is not supplied to the steam generator 4, i.e., even if a driving flow is not supplied to the ejector 1, the pump 3 can move the refrigerant through the refrigerant recovery flow path R11 to the storage tank 7.

<Modification 6>
Fig. 14 is a circuit diagram showing the configuration of an ejector refrigeration unit 62 according to Modification 6. In the above-described third embodiment, the operation stop process is performed by closing the expansion valve 5 and then continuing to drive the pump 3 for a preset period of time. However, in this Modification 6, a liquid level detection sensor Sh for detecting the liquid level in the storage tank 7 is provided.

Then, the control unit C62 continues to drive the pump 3 for a predetermined time until the head difference h from the position of the pump 3 to the liquid level position detected by the liquid level detection sensor Sh becomes greater than the required suction head NPSHR of the pump 3.

<Operation shutdown process>
Fig. 15 is a flow chart showing the procedure of the operation stop process by the control unit C62 of the ejector refrigeration system 62 shown in Fig. 14. This operation stop process is a subroutine corresponding to the operation stop process (step S160) shown in Fig. 2. First, the control unit C62 closes (fully closes) the expansion valve 5 (step S910). Then, based on the detection value of the liquid level detection sensor Sh, it is determined whether the head difference h from the position of the pump 3 to the liquid level detected by the liquid level detection sensor Sh is larger than the required suction head NPSHR of the pump 3 (step S920).

If the head difference h is greater than the required suction head NPSHR (step S920: Yes), the amount of refrigerant stored in the storage tank 7 is sufficient, and the first on-off control valve V11 is switched from open to closed (step S930), the second on-off control valve V12 is closed (step S940), and the pump 3 is stopped (step S950). After that, the controller C62 closes the on-off control valves 20 and 21 (step S960) and returns to step S180. The reason the first on-off control valve V11 and the second on-off control valve V12 are closed is to prevent the refrigerant in the condenser 2 from flowing back to the evaporator 6 side.

On the other hand, if the head difference h is not greater than the required suction head NPSHR (step S920: No), it is determined whether a certain time has elapsed (step S970). This certain time is, for example, a time exceeding a predetermined time, and if the certain time has elapsed, it is the time for which a sufficient amount of refrigerant is stored in the storage tank 7 unless there is an abnormality in the device.

If the fixed time has not elapsed (step S970: No), the process proceeds to step S820, pump 3 continues to be driven, and the judgment process of step S820 is performed. On the other hand, if the fixed time has elapsed (step S970: Yes), it is possible that there is an abnormality in the device, so the first opening/closing control valve V11 is switched from open to closed (step S980), the second opening/closing control valve V12 is closed (step S990), and pump 3 is stopped (step S1000). Thereafter, the control unit C62 closes the opening/closing control valves 20 and 21 (step S1010), issues an alarm notification to an alarm device outside the device (step S1020), and returns to step S180.

The head difference h can be obtained by detecting the liquid level position in the storage tank 7 using this liquid level detection sensor Sh, which reliably prevents cavitation in the pump 3 and ensures that the operating time of the pump 3 during the operation shutdown process is appropriate.

As in variant 5, instead of the liquid level detection sensor Sh, a differential pressure sensor PD may be provided that functions as a differential pressure detection unit that detects the differential pressure ΔP between the suction port of the pump 3 and the refrigerant outlet of the storage tank 7 to determine the head difference h.

<Modification 7>
16 is a circuit diagram showing the configuration of an ejector refrigeration unit 63 according to Modification 7. In Modification 7, the pump 3 is located below the lower end of the storage tank 7, and a pipe L10 connecting the storage tank 7 and the pump 3 is inclined toward the suction port of the pump over the entire area from the refrigerant outlet of the storage tank 7 to the suction port of the pump 3.

In FIG. 16, the pipe L10 is inclined in a substantially straight line. However, this is not limiting; it is sufficient that the inclination of the pipe L10 with respect to the horizontal is 0 degrees, i.e., there is no horizontal portion, and the pipe L10 simply descends monotonically even when coasting. If there is a horizontal portion, air bubbles will accumulate at this position.

In this variation 7, the entire area from the refrigerant outlet of the storage tank 7 to the suction port of the pump 3 is inclined toward the suction port of the pump, so that air bubbles that are not completely condensed in the evaporator 6 and flow into the suction port of the pump 3 are allowed to escape to the storage tank 7 side, thereby preventing cavitation when the pump 3 is started.

<Modification 8>
Fig. 17 is a circuit diagram showing the configuration of an ejector refrigeration system 64 which is Modification 8. The ejector refrigeration system 64 is further provided with a storage tank connecting pipe L11 which connects between a pipe connecting the expansion valve 5 and the evaporator 6 and a pipe connecting the condenser 2 and the storage tank 7, and a third opening/closing control valve V13 provided in the storage tank connecting pipe L11, in comparison with the ejector refrigeration system 61 shown in Fig. 12.

When the degree of superheat at the refrigerant outlet side of the steam generator 4 falls below a preset predetermined degree of superheat during operation of the device, the control unit C64 closes the expansion valve 5, then closes the second on-off control valve V12 and opens the third on-off control valve V13, and continues to drive the pump 3 for a predetermined time, and then closes the first on-off control valve V11 and the third on-off control valve V13 to stop the pump 3, and then closes the on-off control valves 20 and 21 to perform an operation stop process to stop the device. By driving the pump 3 for the predetermined time, a refrigerant recovery flow path R12 is formed, and the refrigerant is stored in the storage tank 7.

If the bottom end of the evaporator 6 is higher than the top end of the storage tank 7, the liquid refrigerant in the evaporator 6 can be recovered into the storage tank 7 by gravity even when the pump 3 is not operating, by opening the first on-off control valve V11.

<Operation shutdown process>
Fig. 18 is a flow chart showing the operation stop processing procedure by the control unit C64 of the ejector refrigeration device 64 shown in Fig. 17. This operation stop processing is a subroutine corresponding to the operation stop processing (step S160) shown in Fig. 2. First, the control unit C64 closes the expansion valve 5 (fully closed) (step S1110). Furthermore, the second opening/closing control valve V12 is closed and the third opening/closing control valve V13 is opened (step S1120). In this state, the first opening/closing control valve V11 is open. As a result, a refrigerant recovery flow path R12 is formed in which the refrigerant is recovered to the storage tank 7 via the first opening/closing control valve V11, the evaporator 6, and the third opening/closing control valve V13.

Then, it is determined whether or not the predetermined time has elapsed (step S1130). If the predetermined time has not elapsed (step S1130: No), this determination process is repeated. The refrigerant moves to the storage tank 7 via the refrigerant recovery flow path R12 until the predetermined time has elapsed.

On the other hand, if the predetermined time has elapsed (step S1130: Yes), the first on-off control valve V11 is closed and the third on-off control valve V13 is closed (step S1140), and the pump 3 is stopped (step S1150). After that, the control unit C64 closes the on-off control valves 20 and 21 (step S1160) and returns to step S180.

<Modification 9>
Fig. 19 is a circuit diagram showing the configuration of an ejector refrigeration system 65 which is Modification 9. The ejector refrigeration system 65 is further provided with a condenser connecting line L12 which connects between a line connecting the expansion valve 5 and the evaporator 6 and a line connecting the second on-off control valve V12 and the condenser 2, and a fourth on-off control valve V14 provided in the condenser connecting line L12, in comparison with the ejector refrigeration system 61 shown in Fig. 12.

When the degree of superheat at the refrigerant outlet side of the steam generator 4 falls below a preset predetermined degree of superheat during operation of the device, the control unit C65 closes the expansion valve 5, then closes the second on-off control valve V12 and opens the fourth on-off control valve, continues to drive the pump 3 for a predetermined time, and then closes the first on-off control valve V11 and the fourth on-off control valve V14 to stop the pump 3, and further closes the on-off control valves 20 and 21 to perform a stop operation process to stop the device. By driving the pump 3 for the predetermined time, a refrigerant recovery flow path R13 is formed, and the refrigerant is stored in the storage tank 7 via the condenser 2.

In this modification 9, the refrigerant that has passed through the evaporator 6 flows into the condenser 2 through a pipe between the ejector 1 and the condenser 2, and the refrigerant dissipates heat in the condenser 2. As a result, if the load on the device that uses the generated cold water becomes smaller due to the device being shut down, etc., the temperature of the refrigerant that has passed through the evaporator 6 may become higher than the condensation temperature of the refrigerant. In this case, however, since heat is dissipated in the condenser 2, it is possible to prevent the liquid phase refrigerant in the storage tank 7 from evaporating due to high temperature refrigerant flowing directly into the storage tank 7 during refrigerant recovery operation at the time of the shutdown process.

<Operation shutdown process>
FIG. 20 is a flow chart showing the operation stop processing procedure by the control unit C65 of the ejector refrigeration device 65 shown in FIG. 19. This operation stop processing is a subroutine corresponding to the operation stop processing (step S160) shown in FIG. 2. First, the control unit C65 closes the expansion valve 5 (fully closed) (step S1210). Furthermore, the second opening/closing control valve V12 is closed and the fourth opening/closing control valve V14 is opened (step S1220). In this state, the first opening/closing control valve V11 is open. As a result, a refrigerant recovery flow path R13 is formed in which the refrigerant is recovered to the storage tank 7 via the first opening/closing control valve V11, the evaporator 6, the fourth opening/closing control valve V14, and the condenser 2.

Then, it is determined whether or not the predetermined time has elapsed (step S1230). If the predetermined time has not elapsed (step S1230: No), this determination process is repeated. The refrigerant moves to the storage tank 7 via the refrigerant recovery flow path R13 until the predetermined time has elapsed.

On the other hand, if the predetermined time has elapsed (step S1230: Yes), the first on-off control valve V11 and the fourth on-off control valve V14 are closed (step S1240), and the pump 3 is stopped (step S1250). After that, the control unit C65 closes the on-off control valves 20 and 21 (step S1260) and returns to step S180.

When applying embodiment 3 and variants 6 to 9 to variants 2 and 3, the above operation stop process becomes a subroutine corresponding to steps S360, S560, and S640.

Furthermore, in the second and third embodiments and their modified examples, the operation stop process can be performed independently without configuring the valve mechanism and valve control such as the on-off control valves 20 and 21 of the steam generator 4 in the first embodiment. This makes it possible to suppress the occurrence of cavitation when the pump is started.

[Fourth embodiment]
21 is a circuit diagram showing the configuration of an ejector refrigeration system 71 according to a fourth embodiment of the present invention. In this fourth embodiment, the refrigerant outlet PT1 of the condenser 2 or the refrigerant outlet PT7 of the storage tank 7 arranged downstream of the condenser 2 is arranged vertically above the refrigerant outlet PT4 of the steam generator 4 to ensure the necessary suction head of the pump 3 and prevent cavitation from occurring when the pump 3 is started.

In FIG. 21, the height hco of the refrigerant outlet PT7 of the storage tank 7 is positioned above the height hgo of the refrigerant outlet PT4 of the steam generator 4, based on the suction port PT2 of the pump 3. At this time, the height (head difference) hco is positioned to be greater than the required suction head NPSHR.

Figure 22 is a schematic diagram showing the state of the liquid-phase refrigerant when the ejector refrigeration device 71 is stopped and heat exchange in the steam generator 4 is insufficient. As shown in Figure 22, when the operation is stopped, the liquid level of the liquid-phase refrigerant in the storage tank 7, the liquid level of the liquid-phase refrigerant above the expansion valve 5, and the liquid level of the liquid-phase refrigerant above the steam generator 4 are all equal.

Figure 23 is a schematic diagram showing the state of the liquid-phase refrigerant when the ejector refrigeration system 71 starts operating and the heat exchange of the steam generator 4 is insufficient. As shown in Figure 23, when the heat exchange of the steam generator 4 is insufficient at the start of operation, the liquid-phase refrigerant on the steam generator 4 side may be discharged in liquid phase to the ejector 1 side, and may even be discharged to the storage tank 7 side via the condenser 2 and circulate. Even if the liquid-phase refrigerant does not circulate, the internal volume of the piping is sufficiently smaller than the volume of the steam generator, so the decrease in the head difference hcL of the storage tank 7 is small and can be ignored.

Figure 21 above shows the state of the liquid-phase refrigerant in the steady-state operation of the ejector refrigeration system 71 when the heat exchange in the steam generator 4 is sufficient. In the steam generator 7, sufficient heat exchange occurs, the refrigerant becomes gaseous and is discharged to the ejector 1 side, and the head difference on the steam generator 7 side becomes low. This prevents cavitation from occurring and reduces the power consumption of the pump 3.

After operation is stopped, once sufficient time has passed for the temperature and pressure to become uniform, the refrigerant will return to the liquid phase state shown in Figure 22.

<Operation control process>
Fig. 24 is a flow chart showing the operation control process procedure by the control unit C71 of the ejector refrigeration system 71 shown in Fig. 21. First, when the control unit C71 receives a cooling operation start command (step S1310), it checks the state (step S1320). This state check is a self-check such as abnormality detection. Then, the pump 3 is started (step S1330). Note that the expansion valve 5 is closed when the operation is stopped, and the expansion valve 5 is closed when the pump 3 is started.

Then, to check whether the heat exchange in the steam generator 4 is sufficient, the degree of superheat ΔTg is calculated from the refrigerant temperature T1 of the refrigerant temperature sensor 22 and the refrigerant pressure P1 of the refrigerant pressure sensor 23 (step S1340). Then, it is determined whether the degree of superheat ΔTg is greater than the predetermined degree of superheat ΔTgo (step S1350). If the degree of superheat ΔTg is not greater than the predetermined degree of superheat ΔTgo (step S1350: No), the process returns to step S1340. If the degree of superheat ΔTg is greater than the predetermined degree of superheat ΔTgo (step S1350: Yes), the degree of opening of the expansion valve 5 is opened to the minimum degree of opening Nmin (step S1360).

Then, the cold water temperature TW detected by the cold water temperature sensor 70 installed in the pipe of the cold water outlet of the evaporator 6 is obtained, and it is determined whether the difference obtained by subtracting the control target temperature TO from the cold water temperature TW is equal to or greater than the predetermined temperature difference ΔTW (step S1370). If the difference is equal to or greater than the predetermined temperature difference ΔTW (step S1370: Yes), the opening of the expansion valve 5 is opened by n pulses (step S1380) and the process proceeds to step S1370. On the other hand, if the difference is not equal to or greater than the predetermined temperature difference ΔTW (step S1370: No), it is determined whether the difference is less than the predetermined temperature difference ΔTW (step S1390). If the difference is less than the predetermined temperature difference ΔTW (step S1390: Yes), the opening of the expansion valve 5 is closed by n pulses (step S1400) and the process proceeds to step S1370.

On the other hand, if the difference is not less than the predetermined temperature difference ΔTW (step S1390: No), an instruction to stop cooling operation is received (step S1410), operation stop control is performed (step S1420), and this process ends.

Note that the valve mechanism and valve control, such as the opening and closing control valve of the steam generator 4 in the first to third embodiments, are omitted. Furthermore, the steam generator 4 can be operated independently without configuring these valve mechanisms and valve controls. This makes it possible to suppress the occurrence of cavitation when the pump is started, and to reduce the power consumption of the pump 3.

In addition, the configurations illustrated in the above embodiments and variations are merely functional schematics, and do not necessarily have to be physically configured as illustrated. In other words, the form of distribution and integration of each device and component is not limited to that illustrated, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various usage conditions, etc.

REFERENCE SIGNS LIST 1 Ejector 2 Condenser 3 Pump 4 Steam generator 5 Expansion valve 6 Evaporator 7 Storage tank 11-13, 51-53, 61-65, 71 Ejector refrigeration device 20, 21, 41 Opening/closing control valve 22 Refrigerant temperature sensor 23 Refrigerant pressure sensor 24 Heat source temperature sensor 30, 31, 40 Check valve 70 Chilled water temperature sensor C1-C3, C51-C53, C61-C65, C71 Control unit h, hcL Head difference L1 Circulation path L2 Branch path L10 Pipe line L11 Storage tank connection pipe line L12 Condenser connection pipe line Nmin Minimum opening P1 Refrigerant pressure PD Differential pressure sensor PT1, PT4, PT7 Refrigerant outlet PT2 Suction port R1, R11, R12, R13 Refrigerant recovery flow path Sh Liquid level detection sensor T1 Refrigerant temperature T2 Heat source temperature TO Control target temperature TW Chilled water temperature ts Time point V1 Refrigerant transfer on/off control valve V11 First on/off control valve V12 Second on/off control valve V13 Third on/off control valve V14 Fourth on/off control valve VB1 Refrigerant transfer check valve ΔP Differential pressure ΔT Predetermined cycle time ΔTW Predetermined temperature difference ΔTg Superheat degree ΔTgo Predetermined superheat degree

Claims (29)

An ejector refrigeration system having a pump for pressurizing a liquid refrigerant, a vapor generator for heating the refrigerant with a heat source to generate a driving flow, an expansion valve for reducing the pressure of the liquid 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 driving flow of refrigerant from the vapor generator, and a condenser for liquefying and cooling the refrigerant mixed with the driving flow after being drawn into the ejector,
an opening/closing control valve is provided on a refrigerant inlet side and a refrigerant outlet side of the steam generator,
a control unit that, when a degree of superheat on a refrigerant outlet side of the steam generator falls below a predetermined degree of superheat during operation of the device, stops the pump and closes the on-off control valve to stop the device, and, when an operation start condition is satisfied, drives the pump and opens the on-off control valve to start the device. An ejector refrigeration system having a pump for pressurizing a liquid refrigerant, a vapor generator for heating the refrigerant with a heat source to generate a driving flow, an expansion valve for reducing the pressure of the liquid 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 driving flow of refrigerant from the vapor generator, and a condenser for liquefying and cooling the refrigerant mixed with the driving flow after being drawn into the ejector,
a check valve is provided on the refrigerant inlet side of the steam generator;
an on- off control valve is provided on the refrigerant outlet side of the steam generator;
a control unit that, when a degree of superheat on a refrigerant outlet side of the steam generator falls below a predetermined degree of superheat during operation of the device, stops the pump and closes the on-off control valve to stop the device, and, when an operation start condition is satisfied, drives the pump and opens the on-off control valve to start the device. An ejector refrigeration system having a pump for pressurizing a liquid refrigerant, a vapor generator for heating the refrigerant with a heat source to generate a driving flow, an expansion valve for reducing the pressure of the liquid 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 driving flow of refrigerant from the vapor generator, and a condenser for liquefying and cooling the refrigerant mixed with the driving flow after being drawn into the ejector,
a check valve is provided on each of the refrigerant inlet and outlet sides of the steam generator;
a control unit that stops the apparatus by performing an operation stop process to stop the pump when a degree of superheat on a refrigerant outlet side of the steam generator falls to a predetermined degree of superheat or lower during operation of the apparatus, and that drives the pump to start the apparatus when an operation start condition is satisfied. The ejector refrigeration system according to claim 3, characterized in that the cracking pressure of the check valve provided on the refrigerant outlet side of the steam generator is higher than the cracking pressure of the check valve provided on the refrigerant inlet side of the steam generator. An ejector refrigeration system according to any one of claims 1 to 4, characterized in that the operation start condition is that the degree of superheat on the refrigerant outlet side of the steam generator exceeds a predetermined degree of superheat. a refrigerant temperature sensor for detecting a refrigerant temperature on a refrigerant outlet side of the steam generator;
a refrigerant pressure sensor for detecting a refrigerant pressure on a refrigerant outlet side of the steam generator;
The ejector refrigeration apparatus according to any one of claims 1 to 5, wherein the control unit determines the degree of superheat using a refrigerant temperature detected by the refrigerant temperature sensor and a refrigerant pressure detected by the refrigerant pressure sensor. a refrigerant temperature sensor for detecting a refrigerant temperature on a refrigerant outlet side of the steam generator;
a refrigerant pressure sensor for detecting a refrigerant pressure on a refrigerant outlet side of the steam generator;
The ejector refrigeration system according to claim 5, wherein the control unit uses a preset refrigerant temperature set value of the refrigerant temperature detected by the refrigerant temperature sensor, or a preset refrigerant pressure set value of the refrigerant pressure detected by the refrigerant pressure sensor, instead of the specified superheat degree of the operation start condition. a heat source temperature sensor for detecting a heat source temperature of a heat source supplied to the steam generator;
The ejector refrigeration system according to claim 5 , wherein the control unit uses a preset heat source temperature setting value of the heat source temperature detected by the heat source temperature sensor, instead of the predetermined degree of superheat of the operation start condition. The ejector refrigeration system according to claim 3 or 4, characterized in that the control unit measures the intermittent operation cycle of the heat source in advance, drives the pump a predetermined time before the start of intermittent operation, drives the pump to start the system if the operation start condition is satisfied, and performs operation stop processing including stopping the pump if the operation start condition is not satisfied even after a certain time has passed. a refrigerant transfer opening/closing control valve is provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector;
3. The ejector refrigeration apparatus according to claim 1, wherein, when a degree of superheat on a refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, continues to drive the pump for a predetermined time, and then closes the refrigerant movement on-off control valve, stops the pump, and closes the on-off control valve to stop the apparatus by performing an operation stop process. a check valve for refrigerant movement is provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector;
3. The ejector refrigeration apparatus according to claim 1, wherein, when a degree of superheat on a refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus , the control unit closes the expansion valve, continues to drive the pump for a predetermined time, and then stops the pump and closes the on-off control valve to stop the apparatus by performing an operation stop process. a refrigerant transfer opening/closing control valve is provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector, and a differential pressure detection unit is provided to detect a differential pressure between the suction port of the pump and the refrigerant outlet of the condenser;
3. The ejector refrigeration apparatus according to claim 1, wherein when a degree of superheat on a refrigerant outlet side of the steam generator falls below a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, and then continues to drive the pump until a head difference corresponding to the differential pressure detected by the differential pressure detection unit becomes larger than a required suction head of the pump, and when the head difference becomes larger than the required suction head of the pump , the control unit closes the refrigerant movement on-off control valve, stops the pump, and closes the on-off control valve to stop the apparatus. a check valve for refrigerant movement is provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector, and a differential pressure detection unit is provided to detect a differential pressure between the suction port of the pump and the refrigerant outlet of the condenser;
3. The ejector refrigeration apparatus according to claim 1, wherein when a degree of superheat on a refrigerant outlet side of the steam generator falls below a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve and then continues to drive the pump until a head difference corresponding to the differential pressure detected by the differential pressure detection unit becomes larger than a required suction head of the pump, and when the head difference becomes larger than the required suction head of the pump, stops the pump and closes the on- off control valve to stop the apparatus. a refrigerant transfer opening/closing control valve is provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector, and a differential pressure detection unit is provided to detect a differential pressure between the suction port of the pump and the refrigerant outlet of the condenser;
The ejector refrigeration apparatus according to any one of claims 3 to 9, characterized in that when a degree of superheat on a refrigerant outlet side of the steam generator falls below a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve and then continues to drive the pump until a head difference corresponding to the differential pressure detected by the differential pressure detection unit becomes larger than a required suction head of the pump, and when the head difference becomes larger than the required suction head of the pump, the control unit closes the refrigerant movement on-off control valve and performs an operation shutdown process to stop the pump and shut down the apparatus. a check valve for refrigerant movement is provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector, and a differential pressure detection unit is provided to detect a differential pressure between the suction port of the pump and the refrigerant outlet of the condenser;
The ejector refrigeration apparatus according to any one of claims 3 to 9, characterized in that when a degree of superheat on a refrigerant outlet side of the steam generator falls below a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve and then continues to drive the pump until a head difference corresponding to the differential pressure detected by the differential pressure detection unit becomes larger than a required suction head of the pump, and when the head difference becomes larger than the required suction head of the pump, performs an operation shutdown process to stop the pump and shut down the apparatus. a storage tank provided downstream of the condenser and configured to store the refrigerant condensed by the condenser;
a first on-off control valve provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector;
a second on-off control valve provided between a discharge port of the ejector and a refrigerant inlet of the condenser,
3. The ejector refrigeration apparatus according to claim 1, wherein, when a degree of superheat on a refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, continues to drive the pump for a predetermined time, and then closes the first on-off control valve and further closes the second on-off control valve to stop the pump and close the on-off control valve, thereby stopping the apparatus. A liquid level detection sensor is provided to detect the liquid level of the storage tank,
17. The ejector refrigeration apparatus according to claim 16, wherein, when a degree of superheat on a refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, and then continues to drive the pump until a head difference from a position of the pump to a liquid level position detected by the liquid level detection sensor becomes larger than a required suction head of the pump, and then closes the first opening/closing control valve, and further closes the second opening/closing control valve to stop the pump and close the opening/closing control valve to stop the apparatus. a storage tank provided downstream of the condenser and configured to store the refrigerant condensed by the condenser;
a first on-off control valve provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector;
a second on-off control valve provided between a discharge port of the ejector and a refrigerant inlet of the condenser,
The ejector refrigeration apparatus according to any one of claims 3 to 9, characterized in that, when a degree of superheat on a refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, continues to drive the pump for a predetermined time, and then closes the first opening/closing control valve, further closes the second opening/closing control valve, and performs operation shutdown processing to stop the pump, thereby stopping the apparatus. A liquid level detection sensor is provided to detect the liquid level of the storage tank,
19. The ejector refrigeration apparatus according to claim 18, wherein, when a degree of superheat on a refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, and then continues to drive the pump until a head difference from a position of the pump to a liquid level position detected by the liquid level detection sensor becomes larger than a required suction head of the pump, and then closes the first opening/closing control valve, further closes the second opening/closing control valve, and performs an operation shutdown process to stop the pump and shut down the apparatus. a storage tank provided downstream of the condenser and configured to store the refrigerant condensed by the condenser;
a first on-off control valve provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector;
a second on-off control valve provided between a discharge port of the ejector and a refrigerant inlet of the condenser;
a storage tank connecting pipe that connects between a pipe that connects the expansion valve and the evaporator and a pipe that connects the condenser and the storage tank;
a third opening/closing control valve provided in the storage tank connecting pipe,
3. The ejector refrigeration apparatus according to claim 1, wherein, when a degree of superheat on a refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, then closes the second on-off control valve and opens the third on-off control valve, continues to drive the pump for a predetermined time, and then closes the first on-off control valve and the third on-off control valve to stop the pump, and further closes the on-off control valve to stop the apparatus by performing an operation shutdown process. A liquid level detection sensor is provided to detect the liquid level of the storage tank,
21. The ejector refrigeration apparatus according to claim 20, wherein, when the degree of superheat on the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, then closes the second on-off control valve and opens the third on-off control valve, continues to drive the pump until a head difference from the position of the pump to the liquid level position detected by the liquid level detection sensor becomes larger than a required suction head of the pump, and then closes the first on-off control valve and the third on-off control valve to stop the pump, and further performs an operation shutdown process to close the on-off control valve to stop the apparatus. a storage tank provided downstream of the condenser and configured to store the refrigerant condensed by the condenser;
a first on-off control valve provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector;
a second on-off control valve provided between a discharge port of the ejector and a refrigerant inlet of the condenser;
a storage tank connecting pipe that connects between a pipe that connects the expansion valve and the evaporator and a pipe that connects the condenser and the storage tank;
a third opening/closing control valve provided in the storage tank connecting pipe,
The ejector refrigeration apparatus according to any one of claims 3 to 9, characterized in that, when a degree of superheat on a refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, then closes the second on-off control valve and opens the third on-off control valve, continues to drive the pump for a predetermined time, and then closes the first on-off control valve and closes the third on-off control valve, and performs an operation shutdown process to stop the pump and shut down the apparatus. A liquid level detection sensor is provided to detect the liquid level of the storage tank,
23. The ejector refrigeration apparatus according to claim 22, wherein, when the degree of superheat on the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, then closes the second on-off control valve and opens the third on-off control valve, continues to drive the pump until a head difference from the position of the pump to the liquid level position detected by the liquid level detection sensor becomes larger than a required suction head of the pump, and then closes the first on-off control valve and closes the third on-off control valve, and performs an operation shutdown process to stop the pump and shut down the apparatus. a storage tank provided downstream of the condenser and configured to store the refrigerant condensed by the condenser;
a first on-off control valve provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector;
a second on-off control valve provided between a discharge port of the ejector and a refrigerant inlet of the condenser;
a condenser connecting pipe that connects between the expansion valve and the evaporator and between the second opening/closing control valve and the condenser;
a fourth on-off control valve provided in the condenser connecting line,
3. The ejector refrigeration apparatus according to claim 1, wherein, when a degree of superheat on a refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, then closes the second on-off control valve and opens the fourth on-off control valve, continues to drive the pump for a predetermined time, and then closes the first on-off control valve and the fourth on-off control valve to stop the pump, and further closes the on-off control valve to stop the apparatus by performing an operation shutdown process. A liquid level detection sensor is provided to detect the liquid level of the storage tank,
25. The ejector refrigeration apparatus according to claim 24, wherein, when the degree of superheat on the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, then closes the second on-off control valve and opens the fourth on-off control valve, continues to drive the pump until a head difference from the position of the pump to the liquid level position detected by the liquid level detection sensor becomes larger than a required suction head of the pump, and then closes the first on-off control valve and the fourth on-off control valve to stop the pump, and further performs an operation shutdown process to close the on-off control valve to stop the apparatus. a storage tank provided downstream of the condenser and configured to store the refrigerant condensed by the condenser;
a first on-off control valve provided between a refrigerant outlet side of the evaporator and a refrigerant suction port of the ejector;
a second on-off control valve provided between a discharge port of the ejector and a refrigerant inlet of the condenser;
a condenser connecting pipe that connects between the expansion valve and the evaporator and between the second opening/closing control valve and the condenser;
a fourth on-off control valve provided in the condenser connecting line,
The ejector refrigeration apparatus according to any one of claims 3 to 9, characterized in that, when a degree of superheat on a refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined degree of superheat during operation of the apparatus, the control unit closes the expansion valve, then closes the second on-off control valve and opens the fourth on-off control valve, continues to drive the pump for a predetermined time, and then closes the first on-off control valve and closes the fourth on-off control valve, and performs an operation shutdown process to stop the pump and shut down the apparatus. A liquid level detection sensor is provided to detect the liquid level of the storage tank,
The ejector refrigeration apparatus according to claim 26, wherein, when the superheat degree on the refrigerant outlet side of the steam generator becomes equal to or lower than a predetermined superheat degree during operation of the apparatus, the control unit closes the expansion valve, then closes the second on-off control valve and opens the fourth on-off control valve, continues to drive the pump until a head difference from the position of the pump to the liquid level position detected by the liquid level detection sensor becomes larger than a required suction head of the pump, and then closes the first on-off control valve and closes the fourth on-off control valve, and performs an operation shutdown process to stop the pump and shut down the apparatus. An ejector refrigeration system according to any one of claims 16 to 27, characterized in that the pump is located below the lower end of the storage tank, and the pipe connecting the storage tank and the pump is inclined toward the suction port of the pump over the entire area from the refrigerant outlet of the storage tank to the suction port of the pump. An ejector refrigeration system according to any one of claims 1 to 28, characterized in that the refrigerant outlet of the condenser or the refrigerant outlet of the storage tank arranged downstream of the condenser is arranged vertically above the refrigerant outlet of the steam generator.

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