JP4973976B2 - Sealed turbo compression refrigerator - Google Patents

Description

  The present invention relates to a turbo compressor for a refrigerator, and more particularly to a hermetic turbo compression refrigerator that circulates a refrigerant in a sealed state.

The refrigerator is a so-called heat pump that operates using liquefied gas as a refrigerant and spends work to transfer heat from a low heat source to a high heat source. The refrigerator usually includes a compressor, a condenser, an expansion valve, and an evaporator. The refrigerant gas is compressed by the compressor to a high temperature and high pressure state, and the refrigerant gas in this state is radiated and liquefied by the condenser. This liquid is expanded by an expansion valve to form a low-temperature and low-pressure gas-liquid mixed state, and heat is removed from the medium to be cooled by an evaporator to evaporate it into a refrigerant gas, which is again sucked into the compressor.
The above-described series of cycles is called a refrigeration cycle. The evaporator absorbs heat from a low heat source and the condenser dissipates heat to a high heat source. When the heat absorption is Qe, the heat release is Qc, and the work heat equivalent of the compressor is AL, Qe / AL is the coefficient of performance COP of the refrigerator and Qc / AL is the operation coefficient of the heat pump.

As the compression ratio increases, the discharge temperature of the compressor increases and the volumetric efficiency decreases. In particular, since the compression ratio increases when the evaporation temperature decreases, the compression operation may be divided into two stages or three stages or more. Such a refrigeration cycle in which the compression operation is performed in multiple stages is called a multistage compression cycle.
Patent Document 1 has already been disclosed as a turbo compressor for a multistage compression cycle. Further, Patent Document 2 is disclosed as a method for cooling the turbo compressor motor.

  The apparatus of Patent Document 1 aims to reduce the thrust force generated by the compression blades in a single-shaft two-stage compressor. As shown in FIG. 4, one of the refrigerants 56 compressed by the first-stage compression blades 54 is used. By-pass pipes 58 and 59 are provided to cool the drive motor from the middle of the outlet pipe 57 on the first stage compression blade 54 side and return to the inlet pipe on the second stage compression blade 55 side after cooling the drive motor. Thus, a resistor 51 corresponding to the pressure loss caused by the refrigerant passing through the drive motor portion is provided between the first-stage outlet pipe and the second-stage inlet pipe.

  The method of Patent Document 2 aims to obtain an equivalent cooling performance without providing blades on the end ring portion of the rotor, and as shown in FIG. 5, on both sides of the mounting position of the rotor 62 of the motor shaft 64. In addition, a disk 63 is provided on the rotor 62 side from the coil end end of the stator 61.

JP-A-5-223090, “turbo compressor” Japanese Patent Laid-Open No. 6-159825, “Cooling method of motor for hermetic turbo refrigerator”

In the apparatus of Patent Document 1, refrigerant gas is used for cooling the drive motor. Therefore, compared with the liquefied refrigerant liquid, the latent heat of vaporization cannot be used, so a large amount of refrigerant gas is required, and there is a problem that the windage loss is large.
In addition, since a resistance 51 corresponding to the pressure loss caused by the refrigerant gas passing through the drive motor portion is provided between the first-stage side outlet pipe 58 and the second-stage side inlet pipe 59, the refrigerant The total amount of gas causes a pressure loss corresponding to this resistance, and the efficiency of the entire refrigerator is lowered.

On the other hand, in the method of Patent Document 2, the liquefied refrigerant liquid is caused to flow by the pressure difference from the high-pressure condenser to the low-pressure evaporator, and a part thereof is between the motor casing 65 and the stator 61 and partly. This is supplied between the stator 61 and the rotor 62 through the inside of the motor shaft 64, cooled, and returned to the evaporator. Accordingly, since the refrigerant liquid cools the stator 61 and the rotor 62 while being in droplets, although the cooling effect is high, the windage of the refrigerant gas containing the droplets is large, and the efficiency as a refrigerator is further reduced. There is a point.
In addition, the pressure in the condenser for supplying the refrigerant liquid is very high compared to the intermediate pressure inside the electric motor, and the refrigerant liquid and refrigerant gas corresponding to the differential pressure are used for cooling. Decreases the efficiency.

  The present invention has been developed to solve such a demand. That is, an object of the present invention is to provide a hermetic turbo compression refrigerator that can reduce windage loss due to a large amount of refrigerant gas or refrigerant gas containing droplets and improve the efficiency of the entire refrigerator.

According to the present invention, a turbo compressor that compresses a refrigerant gas into a high-temperature and high-pressure refrigerant gas;
A condenser that radiates and liquefies the high-temperature and high-pressure refrigerant gas;
An expansion valve for expanding the refrigerant liquid obtained by liquefying the refrigerant gas into a low-temperature low-pressure gas-liquid mixed gas;
And an evaporator that cools a medium to be cooled and vaporizes the gas-liquid mixed gas to form a refrigerant gas, wherein the refrigerant gas vaporized by the evaporator is again sucked by a turbo compressor. ,
A hermetic motor that drives the turbo compressor in a hermetically sealed state, a refrigerant liquid supply pipe that supplies a refrigerant liquid to the hermetic motor, and a refrigerant gas that returns the refrigerant gas evaporated in the hermetic motor to the evaporator A return pipe and
The hermetic motor has an electric motor casing containing a stator and a rotor of the electric motor, and the electric motor casing communicates with the refrigerant liquid supply pipe and indirectly cools the stator with the refrigerant liquid, and the hollow A gas supply port for supplying the refrigerant gas gasified in the jacket to one end of the rotor in the casing, and the other end of the rotor reached from the one end of the rotor through the gap between the stator and the rotor A gas return port for communicating refrigerant gas with the refrigerant gas return pipe,
The turbo compressor is a two-stage turbo compressor composed of a first-stage centrifugal compressor and a second-stage centrifugal compressor,
The expansion valve comprises a high pressure side expansion valve and a low pressure side expansion valve,
Furthermore, it is located between the high-pressure side expansion valve and the low-pressure side expansion valve, and comprises an economizer that separates the refrigerant gas from the gas-liquid mixed gas and guides it to the intermediate stage of the two-stage turbo compressor,
One end of the refrigerant liquid supply pipe communicates with an economizer to supply refrigerant liquid therefrom, and a sealed turbo compression refrigerator is provided.

  The refrigerant gas return pipe includes an orifice or a valve that adjusts the flow rate of the refrigerant gas flowing due to the pressure difference.

  The hollow jacket is preferably a spiral or similar channel surrounding the stator.

  Further, the flow path area of the hollow jacket gradually increases or increases stepwise from the inlet toward the outlet.

  A temperature detector for detecting a temperature of the refrigerant gas in the refrigerant gas return pipe, a temperature of the refrigerant gas return pipe itself, or a temperature in the electric motor casing; and a flow rate adjusting valve for adjusting a flow rate of the refrigerant liquid supply pipe; And a temperature controller for controlling the flow rate adjusting valve according to the temperature detected by the temperature detector.

  Moreover, it is preferable that the gas supply port which supplies the said refrigerant gas to the one end part of the rotor in a casing is the other side to which the force of a thrust direction is applied.

According to the configuration of the present invention, the refrigerant liquid is supplied from the refrigerant liquid supply pipe into the hollow jacket of the hermetic motor, and the stator is indirectly cooled using the latent heat of vaporization from the refrigerant liquid to the gas in the hollow jacket. Therefore, the stator can be cooled with a small amount of refrigerant liquid.
Further, the rotor gas is cooled by allowing the refrigerant gas gasified in the hollow jacket to pass through the gap between the stator and the rotor. The stator is sufficiently cooled by the refrigerant liquid, and the refrigerant gas mainly works to cool the rotor. Therefore, the amount of gas is smaller than that of a structure in which the stator and rotor are cooled only by gas, and windage loss can be greatly reduced. Also, the refrigerant gas that contacts the rotor does not contain many droplets. Therefore, the number of droplets is reduced as compared with the case where the refrigerant liquid is directly injected from the rotor, and the windage loss can be similarly reduced.
Therefore, it is possible to reduce windage loss due to a large amount of refrigerant gas or refrigerant gas containing droplets, and to improve the efficiency of the entire refrigerator.

  In the case of an economizer cycle in which the turbo compressor is a two-stage turbo compressor and an economizer is provided between the high pressure side expansion valve and the low pressure side expansion valve, the refrigerant is supplied from the economizer to the hermetic motor via the refrigerant liquid supply pipe. By supplying the liquid, the pressure in the economizer is lower than the pressure in the condenser and higher than the pressure in the rotor, so the pressure loss associated with the supply of the refrigerant liquid is small. A decrease in efficiency can be prevented.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

  1 is a configuration diagram of a hermetic turbo compression refrigerator of the present invention, FIG. 2 is a schematic diagram of the hermetic turbo compression refrigerator of FIG. 1, and FIG. 3 is a hermetic turbo compression refrigerator of FIG. It is a pressure-enthalpy diagram in a machine.

In these drawings, the hermetic turbo compression refrigerator 10 of the present invention includes a turbo compressor 12, a condenser 14, an expansion valve 16, and an evaporator 18.
The turbo compressor 12 compresses the refrigerant gas 1 into a high-temperature and high-pressure refrigerant gas 5. The condenser 14 dissipates heat from the high-temperature and high-pressure refrigerant gas 5 to liquefy the refrigerant gas into the refrigerant liquid 6. The expansion valve 16 expands the liquefied refrigerant liquid 6 into a low-temperature and low-pressure gas-liquid mixed gas 9. The evaporator 18 cools the medium to be cooled to vaporize the gas-liquid mixed gas 9 to make the refrigerant gas 1. The refrigerant gas 1 exiting the evaporator 18 is again sucked into the turbo compressor 12.

  1 and 2, a turbo compressor 12 is a two-stage turbo compressor composed of a first-stage centrifugal compressor 12a and a second-stage centrifugal compressor 12b, and refrigerant gas 2 compressed by the first-stage centrifugal compressor 12a. The refrigerant gas 3 is mixed from the gas-liquid mixed gas 7 in the middle of expansion into the refrigerant gas 4, which is compressed by the second-stage centrifugal compressor 12b into the high-temperature and high-pressure refrigerant gas 5.

The expansion valve 16 includes a high-pressure side expansion valve 16a and a low-pressure side expansion valve 16b. The hermetic turbo compression refrigerator 10 of the present invention further includes an economizer 19.
The economizer 19 is located between the high-pressure side expansion valve 16a and the low-pressure side expansion valve 16b, and separates the refrigerant gas 3 from the gas-liquid mixed gas 7 in the middle of expansion and guides it to the intermediate stage of the two-stage turbo compressor 12. It has become.

In the sealed turbo compression refrigerator 10 of the present invention, for example, a refrigerant that evaporates around 5 to 7 ° C. at 0.1 MPa and becomes 2 MPa and around 100 to 130 ° C. around a compression ratio of 20 is used. As such a refrigerant, for example, R-114 can be used.
In this case, the pressure of 3 - in enthalpy diagram, the maximum pressure _{P H} is 2MPa example, minimum pressure _{P L} is 0.1MPa, for example. Further, the pressure _{P m} in the economizer 19 is approximately 0.45MPa longitudinal its intermediate pressure.
Moreover, in FIG. 2, the heat radiation temperature in the condenser 14 is 100-130 degreeC, for example, and the cooling temperature in the evaporator 18 is 5-7 degreeC, for example. Further, the temperature in the intermediate stage of the two-stage turbo compressor 12 is about 50 ° C.
Therefore, in this example, the medium to be cooled can be cooled at a low temperature of 5 to 7 ° C.

In FIG. 1, the hermetic turbo compression refrigerator 10 of the present invention further includes a hermetic motor 20, a refrigerant liquid supply pipe 32, and a refrigerant gas return pipe 34.
The hermetic motor 20 includes an electric motor casing 23 containing a stator 21 and a rotor 22 of the electric motor. The rotation of the rotor 22 is transmitted to the speed increasing shaft 26 via speed increasing gears 24 and 25, and the first The impellers of the stage centrifugal compressor 12a and the second stage centrifugal compressor 12b are rotationally driven in a sealed state.

The electric motor casing 23 has a hollow jacket 23a, a gas supply port 23b, and a gas return port 23c.
The hollow jacket 23a is a spiral or similar channel surrounding the stator 21, and communicates with one end (the left end in the figure) of the refrigerant liquid supply pipe 32 to indirectly cool the stator 21 with the refrigerant liquid. The spiral channel may be supplied from one side of the stator as in this example or may be supplied from both ends.

  Moreover, it is preferable that the flow path area of the hollow jacket 23a gradually increases or increases stepwise from the inlet toward the outlet. With this configuration, the volume of the refrigerant expands as the refrigerant liquid gasifies into the refrigerant gas in the flow path, but an increase in pressure loss can be prevented by increasing the flow path area.

  Further, the gas supply port 23b for supplying the refrigerant gas to one end portion of the rotor in the casing is preferably on the opposite side (left side in this example) to which a force in the thrust direction is applied. With this configuration, it is possible to reduce the thrust force by canceling the thrust force generated by the speed increasing gear 24 with the thrust force generated by the pressure difference of the rotor 22.

The gas supply port 23b is a hole that communicates the end of the spiral flow path (the left end in this figure) with the inside of the casing, and the refrigerant gas gasified in the hollow jacket 23a is connected to one end of the rotor 22 in the casing (this Supply to the left end in the figure.
The gas return port 23c is a hole that communicates the inside and the outside of the casing, and passes between the stator 22 and the rotor 21 (gap) from one end portion (the left end portion in this figure) of the rotor 21 to the rotor 21. The refrigerant gas reaching the other end (the right end portion in this figure) is communicated with the refrigerant gas return pipe 34.

  One end (right end in the figure) of the refrigerant liquid supply pipe 32 communicates with the refrigerant liquid 8 in the economizer 19 and is a piping line that supplies the refrigerant liquid 8 to the hollow jacket 23a of the hermetic motor. In addition, as shown with the arrow of a broken line in a figure, you may connect one end of the refrigerant | coolant liquid supply pipe | tube 32 to the condenser 14, and may supply a refrigerant | coolant liquid here.

A flow rate adjustment valve 32 a for adjusting the flow rate of the refrigerant liquid is provided in the middle of the refrigerant liquid supply pipe 32. Further, in FIG. 1, a first temperature detector 33a that detects the temperature of the refrigerant gas in the refrigerant gas return pipe 34 or the temperature of the refrigerant gas return pipe itself, and a second temperature detector 33b that detects the temperature in the motor casing. And a temperature controller 33c for controlling the flow rate adjusting valve according to the temperature detected by the temperature detector 33a or 33b.
With this configuration, if the detected temperature (that is, the outlet temperature) of the temperature detector 33a or 33b is lower than the specified value, the refrigerant amount is reduced because it is too cold, and conversely if it is higher, the refrigerant amount is increased because it is not too cold. it can.

  The refrigerant gas return pipe 34 is a piping line that returns the refrigerant gas, in which the refrigerant liquid is evaporated by the hermetic motor, to the evaporator 18 from the gas return port 23c. The refrigerant gas return pipe 34 includes an orifice 34a or a valve for adjusting the flow rate of the refrigerant gas flowing due to the pressure difference.

  Further, in FIG. 1, a refrigerant liquid return pipe 35 that communicates one end of the rotor in the casing into which the refrigerant gas gasified in the hollow jacket flows and the evaporator and returns the refrigerant liquid from the casing to the evaporator. Prepare.

According to the configuration of the present invention described above, the refrigerant liquid is supplied from the refrigerant liquid supply pipe 32 into the hollow jacket of the hermetic motor 20, and the stator is utilized in the hollow jacket 23a using the latent heat of vaporization from the refrigerant liquid to the gas. Is indirectly cooled, so that the stator can be cooled with a small amount of the refrigerant liquid by utilizing the latent heat of vaporization from the refrigerant liquid to the gas.
Further, the refrigerant gas gasified in the hollow jacket is passed through the gap between the stator 21 and the rotor 22 to cool the stator 21 and the rotor 22. The stator is sufficiently cooled by the refrigerant liquid, and the refrigerant gas mainly works to cool the rotor. Therefore, the amount of gas is smaller than that of a structure in which the stator and rotor are cooled only by gas, and windage loss can be greatly reduced. Also, the refrigerant gas that contacts the rotor does not contain many droplets. Therefore, the number of droplets is reduced as compared with the case where the refrigerant liquid is directly injected from the rotor, and the windage loss can be similarly reduced.
Therefore, it is possible to reduce windage loss due to a large amount of refrigerant gas or refrigerant gas containing droplets, and to improve the efficiency of the entire refrigerator.

  In the case of an economizer cycle in which the turbo compressor is a two-stage turbo compressor and an economizer 19 is provided between the high-pressure side expansion valve 16a and the low-pressure side expansion valve 16b, the economizer 19 passes through the refrigerant liquid supply pipe 32. By supplying the refrigerant liquid to the hermetic motor 20, the pressure in the economizer 19 is lower than the pressure in the condenser 14 (for example, 2 MPa) and higher than the pressure in the rotor portion (in the casing) (for example, about 0. 45 MPa), the pressure loss associated with the supply of the refrigerant liquid is small, and the efficiency of the entire refrigerator can be prevented from decreasing accordingly.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

It is a block diagram of the hermetic turbo compression refrigerator of the present invention. FIG. 2 is a schematic view of the hermetic turbo compression refrigerator of FIG. 1. FIG. 3 is a pressure-enthalpy diagram in the hermetic turbo compression refrigerator of FIG. 2. 2 is a configuration diagram of an apparatus disclosed in Patent Document 1. It is a block diagram of the apparatus of patent document 2. FIG.

Explanation of symbols

1, 2, 3, 4, 5 refrigerant gas, 6 refrigerant liquid,
7 gas-liquid mixed gas, 8 refrigerant liquid, 9 liquid mixed gas,
10 hermetic turbo compression refrigerator, 12 turbo compressor,
12a first stage centrifugal compressor, 12b second stage centrifugal compressor,
14 condenser, 16 expansion valve,
16a high pressure side expansion valve, 16b low pressure side expansion valve,
18 Evaporator, 19 Economizer,
20 hermetic motor, 21 stator, 22 rotor,
23 motor casing, 23a hollow jacket,
23b gas supply port, 23c gas return port,
24, 25 Speed increasing gear, 26 Speed increasing shaft 32 Refrigerant liquid supply pipe, 32a Flow rate adjusting valve,
33a, 33b temperature detector, 33c temperature controller,
34 Refrigerant gas return pipe, 34a Orifice 35 Refrigerant liquid return pipe

Claims (6)

A turbo compressor that compresses the refrigerant gas into a high-temperature and high-pressure refrigerant gas;
A condenser that radiates and liquefies the high-temperature and high-pressure refrigerant gas;
An expansion valve for expanding the refrigerant liquid obtained by liquefying the refrigerant gas into a low-temperature low-pressure gas-liquid mixed gas;
And an evaporator that cools a medium to be cooled and vaporizes the gas-liquid mixed gas to form a refrigerant gas, wherein the refrigerant gas vaporized by the evaporator is again sucked by a turbo compressor. ,
A hermetic motor that drives the turbo compressor in a hermetically sealed state, a refrigerant liquid supply pipe that supplies a refrigerant liquid to the hermetic motor, and a refrigerant gas that returns the refrigerant gas evaporated in the hermetic motor to the evaporator A return pipe and
The hermetic motor has an electric motor casing containing a stator and a rotor of the electric motor, and the electric motor casing communicates with the refrigerant liquid supply pipe and indirectly cools the stator with the refrigerant liquid, and the hollow A gas supply port for supplying the refrigerant gas gasified in the jacket to one end of the rotor in the casing, and the other end of the rotor reached from the one end of the rotor through the gap between the stator and the rotor A gas return port for communicating refrigerant gas with the refrigerant gas return pipe,
The turbo compressor is a two-stage turbo compressor composed of a first-stage centrifugal compressor and a second-stage centrifugal compressor,
The expansion valve comprises a high pressure side expansion valve and a low pressure side expansion valve,
Furthermore, it is located between the high-pressure side expansion valve and the low-pressure side expansion valve, and comprises an economizer that separates the refrigerant gas from the gas-liquid mixed gas and guides it to the intermediate stage of the two-stage turbo compressor,
One end of the refrigerant liquid supply pipe communicates with an economizer and supplies the refrigerant liquid therefrom.   2. The hermetic turbo compression refrigerator according to claim 1, wherein the refrigerant gas return pipe includes an orifice or a valve for adjusting a flow rate of the refrigerant gas flowing due to a pressure difference.   2. The hermetic turbo compression refrigerator according to claim 1, wherein the hollow jacket is a spiral channel surrounding the stator or a similar channel.   4. The hermetic turbo compression refrigerator according to claim 3, wherein the flow path of the hollow jacket gradually increases or increases stepwise from the inlet toward the outlet. 5.   A temperature detector for detecting a temperature of the refrigerant gas in the refrigerant gas return pipe, a temperature of the refrigerant gas return pipe itself, or a temperature in the electric motor casing; a flow rate adjusting valve for adjusting a flow rate of the refrigerant liquid supply pipe; 2. The hermetic turbo compression refrigerator according to claim 1, further comprising a temperature controller that controls the flow rate control valve based on a temperature detected by the temperature detector.   2. The hermetic turbo compression refrigerator according to claim 1, wherein a gas supply port that supplies the refrigerant gas to one end of a rotor in a casing is an opposite side to which a force in a thrust direction is applied.

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