JPS6360301B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a centrifugal heat pump equipped with a centrifugal compressor.

[Conventional technology]

In conventional centrifugal heat pumps, when operated at high hot water temperatures, the discharge gas temperature of the compressor rises and there is a risk of thermal decomposition of the refrigerant, making it impossible to operate at high hot water temperatures.

In order to solve this problem, liquid refrigerant is injected near the impeller outlet to cool the discharged gas.

[Problem that the invention seeks to solve]

However, in such conventional devices, the coefficient of performance was poor depending on the operating conditions, and energy loss was involved.

SUMMARY OF THE INVENTION An object of the present invention is to provide a centrifugal heat pump capable of solving the above-mentioned conventional problems and minimizing a decrease in the coefficient of performance of the heat pump caused by injection of refrigerant liquid.

The present invention includes a centrifugal compressor equipped with a nozzle opened on the wall of a gas passage connecting an impeller outlet and a vortex chamber, and an injection device for injecting a liquid phase refrigerant into the gas passage through the nozzle, It is characterized by comprising a detection device that detects the opening degree of the inlet vane, and a control device that controls the injection device to inject the refrigerant liquid when the opening degree of the inlet vane is less than or equal to a predetermined value. It is a centrifugal heat pump.

〔Example〕

Embodiments of the present invention will be described using the drawings.

In Figure 1, 1 is an evaporator, 2 is a heat exchanger tube, 3 is a condenser, 4 is a heat exchanger tube, 5 is a suction tube, 10 is a speed increaser, 1
1 is an electric motor. A nozzle 13 that opens into the gas passage 8 is provided on the wall surface of the gas passage 8 that connects the outlet of the impeller 6 of the centrifugal compressor and the volute chamber 7, and a solenoid valve 1 is installed between the nozzle 13 and the condenser float chamber 12.
9 and a pump 20 via piping 14,
Form the injector. Furthermore, an opening degree detection device 17 is provided to detect the opening degree of the suction vane 9 of the compressor, and when the opening degree of the suction vane 9 is smaller than a predetermined value, a controller 18, which is a control device that controls the injection device, is provided. Then, the pump is operated, and the solenoid valve 19 is opened, and the liquid refrigerant is supplied to the nozzle 13.
The gas is injected into the gas passage 8 through the gas passageway 8.

Before going into an explanation of the operation of the heat pump having the configuration shown in Fig. 1, it is important to note that when a heat pump is used for producing high-temperature hot water, which is suitable for the subject of the present invention, the compression How the temperature of the machine discharge gas changes will be explained with reference to FIG.

Figure 4 is data obtained through experiments by the inventor and discloses the relationship between the vane opening degree and the compressor discharge gas temperature when producing hot water at 60°C. In the figure, curves A-B-C represent the discharge gas temperature when a conventional heat pump is used, and curves D-E-F represent the discharge gas temperature when liquid refrigerant is injected into the passage from the impeller outlet to the volute chamber. It shows the change in temperature.

According to curve B-C, even if the refrigerant liquid is not injected, if the vane opening is at least a predetermined value, the temperature exceeds 100°C, which the inventor has set as the limit temperature at which thermal decomposition of the refrigerant can be avoided. It turns out there isn't. However, it has been found that when the vane opening is small, the temperature of the discharged gas rises rapidly, as shown by the curve A-B. In addition, according to curve D-E-F, when injecting refrigerant liquid to cool refrigerant gas, the compressor discharge gas temperature will be below the limit temperature (100℃) to avoid thermal decomposition over the entire vane opening degree. It turns out that it can be kept.

On the other hand, regarding the coefficient of performance of heat pumps with and without injection of refrigerant liquid, the inventor's experiments revealed that when injection is performed, the loss due to collision between refrigerant liquid and refrigerant gas is greater than when injection is not performed. It was found that the coefficient of performance deteriorated by 2 to 3% as the pump power of the refrigerant liquid increased.

Therefore, the refrigerant liquid should be injected within the minimum necessary range, and when operating the heat pump, the refrigerant injection should be performed under conditions where the vane opening degree is small, as shown by curve D-E-B-C in Figure 4. It was found that it is desirable in terms of power consumption to stop the injection of refrigerant when the vane opening is above a predetermined value.

The embodiment shown in FIG. 1 was realized based on this knowledge, and the operation of this heat pump will be explained below.

The refrigerant liquid taken out from the condenser float chamber 12 is injected from the nozzle 13 into the gas passage 8 connecting the outlet of the impeller 6 and the swirl chamber 7. In FIG. 1, it is detected whether the compressor vane opening is below or above a predetermined opening required for refrigerant injection through an opening detecting device 17 using a limit switch or the like, and a signal is sent to the controller 18. send.

The controller 18 operates the pump 20 when the vane opening is below a predetermined value, and
The solenoid valve 19 is opened and the refrigerant liquid is injected into the gas passage 8 through the nozzle 13 to cool the refrigerant gas. When the vane opening is greater than or equal to a predetermined value, the controller 18 stops the pump 20 and opens the solenoid valve 19 to stop the injection of refrigerant.

As described above, according to the embodiment shown in FIG. 4, the refrigerant liquid is injected only when the suction vane opening is smaller than the predetermined opening, which is necessary to avoid thermal decomposition of the refrigerant, as described above. Under conditions where the vane opening degree is large and there is little possibility of thermal decomposition, injection of refrigerant liquid is stopped to prevent a drop in the coefficient of performance of the heat pump, so it is possible to maintain the coefficient of performance of the heat pump at its best depending on the operating conditions. .

Although the pump 20 is used to inject the refrigerant liquid in FIG. 1, the gas passage 8 originally has the effect of being a diffuser, so it is normally kept at a lower pressure than the condenser float chamber 12. It is also possible to supply the refrigerant liquid by utilizing the pressure difference between the gas passage 8 and the condenser float chamber 12, and in that case, the pump 20 may be omitted.

2 and 3 show an example of the operational relationship between the suction vane opening detection device 17, the pump 20, and the electromagnetic valve in the embodiment shown in FIG. 1, and FIG. 2 is a sequence diagram, and FIG. 1 is a structural explanatory diagram of a vane opening degree detection device 17. FIG.

In FIG. 2, the power relay 25 of the pump 20 and the power relay 26 of the solenoid valve are configured to be driven via a limit switch 23 which shorts out when the vane opening is smaller than a predetermined value.

In FIG. 3, the configuration is such that when the suction vane 9 becomes smaller than a predetermined value, the lever 27 is moved by the cam 24, and the contacts of the limit switch 23 are short-circuited.

The operation will be explained below. When the vane 9 rotates and becomes smaller than a predetermined value, the lever of the limit switch 23 is pushed down by the action of the cam 24, the contacts 23 are short-circuited, the pump relay 25 and the solenoid valve relay 26 are energized, and the pump and solenoid valve are activated. It is activated and the refrigerant liquid is injected.

〔Effect of the invention〕

According to the present invention, refrigerant liquid is injected only when the suction vane opening is smaller than a predetermined opening, which is necessary to avoid thermal decomposition of the refrigerant, and the vane opening is less likely to cause thermal decomposition. In order to prevent a decrease in the coefficient of performance of the heat pump by stopping the injection of refrigerant liquid under conditions of large However, it is possible to improve efficiency, which has an extremely large practical effect.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a flow diagram of another embodiment, FIG. 2 is a sequence diagram showing a part of the sequence, FIG. 3 is an explanatory diagram of a vane opening degree detector, and FIG. FIG. 4 is a diagram showing the relationship between vane opening and discharge gas temperature. 1... Evaporator, 2... Heat exchanger tube, 3... Condenser,
4... Heat exchanger tube, 5... Suction pipe, 6... Impeller, 7
... Volute chamber, 8 ... Gas passage, 9 ... Suction vane, 10 ... Speed increaser, 11 ... Electric motor, 12 ...
Condenser float chamber, 13... Nozzle, 14... Piping, 15... Condenser buffer plate, 16... Float valve, 17... Opening degree detection device, 18... Controller, 19... Solenoid valve, 20... ...Pump, 23...
...Limit switch, 24...Cam, 25...Pump relay, 26...Solenoid valve relay, 27...Lever.

Claims (1)

[Claims] 1 A centrifugal compressor equipped with a nozzle opened on the wall of a gas passage connecting an impeller outlet and a vortex chamber, and an injection device for injecting liquid phase refrigerant into the gas passage through the nozzle, The present invention is characterized by comprising an opening detection device that detects an opening, and a control device that controls the injection device to inject the refrigerant liquid when the opening of the inlet vane is less than or equal to a predetermined value. Centrifugal heat pump.