JP5173477B2 - Hybrid refrigerator - Google Patents

Description

  The present invention relates to a refrigerator equipped with a compression refrigeration cycle having a prime mover and a compressor driven by its shaft output.

  Driving a compression refrigerator with a prime mover such as a gas engine is widely performed, but waste heat is often discarded except for use in hot water supply. Exhaust heat absorption refrigerators driven by exhaust heat are often used in cogeneration mainly for power generation, but are rarely provided with compression refrigerators. In this respect, in addition to the prime mover, if the equipment is configured with a compression refrigeration machine and an exhaust heat absorption chiller, the entire equipment becomes larger. This is probably because it is difficult to achieve both, and it is difficult to make a direct expansion type that directly evaporates the refrigerant in the room.

In order to improve these defects to some extent and to effectively use the exhaust heat generated by the prime mover, both the compression refrigeration cycle and the exhaust heat absorption refrigeration cycle are provided, and both cycles share a condenser and an evaporator to combine ammonia. A hybrid cycle has been proposed (Non-Patent Document 1).
On the other hand, Non-Patent Document 2 proposes a structure in which a compressor is inserted between an evaporator and an absorber of an exhaust heat absorption refrigeration cycle.

Optimization study of combined refrigeration cycles driven by an engine, Yang Zhao est. , Applied Energy 76 (2003) 379-389. Hybrid Compression / Absorption Type Heat Utilization System, T.A. Karimata etc. , 6th IEA International Energy Agency Heat Pump Conference 1999 “Heat Pump-a Benefit for the Environment” May 31-June 2, 1999, Berlin, P34.

  However, in the ammonia hybrid cycle disclosed in Non-Patent Document 1, the refrigerant of the evaporator is distributed to the compressor suction and the absorber using different mechanisms, and the load sharing is difficult, and the absorber side There is a risk that the moisture of the water will be mixed into the compression cycle side and cause the deterioration of the performance of the lubricating oil of the compressor and the deterioration of the performance of the evaporator. Furthermore, in this ammonia hybrid cycle, it is necessary to provide a rectifier in the steam generator, which causes a decrease in performance. The absorber in this example plays a role similar to the condenser in the second embodiment of the present application shown in FIG.

  On the other hand, as disclosed in Non-Patent Document 2, when a structure in which a compressor is inserted between the evaporator and the absorber of the exhaust heat absorption refrigeration cycle is used, the problem of refrigerant distribution is solved. When the machine is driven by an engine as a prime mover, the capacity of the compressor is excessive with respect to the evaporation capacity of the regenerator of the exhaust heat absorption refrigeration cycle, and the cycle cannot be established.

  An object of the present invention is to obtain a refrigerator capable of effectively utilizing exhaust heat generated from a prime mover with generation of shaft output in a refrigerator equipped with a prime mover capable of obtaining shaft output and a compression refrigeration cycle. It is in.

In order to achieve the above object, the characteristic configuration of the hybrid refrigerator according to the present application is as follows:
Refrigerant vapor generated in the evaporator is sequentially compressed by a low-pressure compressor and a high-pressure compressor, and the high-pressure refrigerant vapor generated by the high-pressure compressor is condensed in a condenser to form a refrigerant liquid, and the refrigerant liquid is expanded by an expansion valve. Provided with a compression refrigeration cycle that expands in the evaporator and evaporates in the evaporator to generate cold.
Provide a prime mover that generates shaft output,
A steam generation mechanism that obtains steam of a working medium by exhaust heat recovered from the prime mover, an expander that expands the steam generated by the steam generation mechanism to obtain a shaft output, and a working medium that has been expanded by the expander A steam cycle with a condenser to return the liquid to the liquid,
The low pressure compressor works by the shaft output of the prime mover, and the high pressure compressor works by the shaft output of the expander.

This hybrid refrigerator includes a compression refrigeration cycle, a steam cycle, and a prime mover. Then, by operating the prime mover, the shaft output is used as the power for the low pressure compressor, the exhaust heat is taken out as the shaft output of the expander through the steam cycle, and the shaft output is used as the power for the high pressure compressor. To do.
Here, the low-pressure compressor and the high-pressure compressor are connected in series, and the refrigerant vapor generated in the evaporator constituting the compression refrigeration cycle is sequentially compressed. In this two-stage compression, since the refrigerant compressed by the low pressure compressor is further compressed with respect to the compression by the high pressure compressor, the required power becomes relatively small and is recovered by the steam cycle. Power that can be generated by exhaust heat can be fully covered. Further, a small compressor that can be driven by exhaust heat can be used for the high-pressure compressor. Furthermore, in this configuration, the refrigerant circulating in the compression refrigeration cycle is compressed in its entirety, so that the problem of refrigerant distribution as described above does not occur.
Then, the refrigerant obtained through the two-stage compression process is sent to the condenser to be condensed, expanded by the expansion valve, and further evaporated by the evaporator, thereby reducing the shaft output and exhaust heat generated from the prime mover. Utilizing this, cold energy can be obtained with a compact device configuration.

With the above configuration, the working medium circulating in the steam cycle is a refrigerant solution circulating in the compression refrigeration cycle, and the steam generation mechanism regenerates the working medium by exhaust heat recovered by the cooling water of the prime mover. And a separator that separates the working medium regenerated by the regenerator into a low-concentration refrigerant solution and a high-concentration vapor,
It is preferable that a low-concentration solution return path for returning the low-concentration solution to the condenser is provided, and the high-concentration steam is sent to the expander.

In this hybrid refrigerator, the working medium circulating in the vapor cycle is used as a refrigerant solution circulating in the compression refrigeration cycle, so that the medium can be shared. Therefore, even if the refrigerant leaks from the compressor side to the expander side to some extent, there is no fear of having a great influence.
Then, the steam generation mechanism separates the regenerator that regenerates the working medium by exhaust heat recovered by the cooling water of the prime mover, and the working medium regenerated by the regenerator into a low-concentration refrigerant solution and high-concentration steam. The low concentration solution separated by the separator is returned to the condenser via the low concentration solution return path, and the high concentration steam is sent to the expander. In this way, in the steam generation mechanism, the regenerator can play a role in the exhaust heat absorption refrigeration cycle, and only the high-concentration steam obtained can be expanded while utilizing the exhaust heat for regeneration of the working medium. The feed shaft output can be obtained. In this configuration, the regenerator pressure, that is, the pressure of the high-concentration steam can be adjusted by the concentration of the solution fed into the regenerator, so that the pressure ratio of the expander can be appropriately maintained so as to increase the efficiency.

In this configuration, more specifically, the refrigerant circulating in the compression refrigeration cycle is ammonia, the working medium circulating in the vapor cycle is a mixed medium of ammonia and water, and the high pressure compressor and the expander are directly connected. expander side pressure of the shaft, so that is lower than the compressor outlet pressure, the ammonia concentration of the working medium that has been set.
In the hybrid refrigerator having this configuration, the high pressure compressor and the expander are directly connected (as a so-called turbocharger), the middle is sealed, and the expander side of the shaft is slightly lower than the compressor side. Therefore, in this structure, leakage occurs only from the high-pressure compressor (compression refrigeration cycle) side to the expander (steam cycle) side, and the leakage does not affect the refrigerant component circulating in the compression refrigeration cycle, and the expander side If there is a small amount of leakage, there is almost no effect. Accordingly, it is possible to prevent deterioration of the lubricating oil of the compressor in the low-pressure compressor and the high-pressure compressor provided in the compression refrigeration cycle, and it is possible to design the entire refrigerator as an integral unit.

In the configuration described so far, the refrigerant sent from the low-pressure compressor to the high-pressure compressor is the liquid of the working medium sent from the condenser to the steam generating mechanism, the steam from the steam generating mechanism to the expander, or those It is preferable that the heat exchange is possible with both.
By adopting this configuration, the efficiency on the steam cycle side is improved, and the compressor side has a so-called two-stage compression / intermediate cooling structure, so the efficiency can also be improved.

  Hereinafter, embodiments of the present application will be described with reference to the drawings. In this specification, the first embodiment (FIG. 1), the second embodiment (FIG. 2), and the third embodiment (FIG. 3) are introduced. First, the common configuration will be described.

[Common configuration]
A combined system 100, which is a hybrid refrigerator according to the present application, includes a prime mover 101, a compression refrigeration cycle 102, and a steam cycle 103.

  The prime mover 101 is configured to be capable of outputting a shaft output, and exhaust heat generated with the output of the shaft output is recovered by the cooling water c.

The configuration of the compression refrigeration cycle 102 is common to all forms, and the compressor 1 includes a low-pressure compressor 1a and a high-pressure compressor 1b connected in series. A configuration is employed in which the low pressure compressor 1a is operated by the shaft output of the prime mover 101, and a configuration is employed in which the high pressure compressor 1b is operated by the shaft output of the expander 12 constituting the steam cycle 102 described later.
More specifically, the compression refrigeration cycle 102 includes, as is well known, an evaporator 2, a compressor 1 (a low-pressure compressor 1 a and a high-pressure compressor 1 b connected in series), a condenser 3, and an expansion valve 4. Are arranged in the order of description in a circulation circuit in which the refrigerant circulates. Then, the refrigerant vapor generated in the evaporator 2 is sequentially compressed by the low-pressure compressor 1a and the high-pressure compressor 1b, and the high-pressure refrigerant vapor generated by the high-pressure compressor 1b is condensed by the condenser 3 to obtain a refrigerant liquid. At the same time, the refrigerant liquid is expanded by the expansion valve 4, further evaporated by the evaporator 2, and the evaporator 2 is configured to take out cold heat as the refrigerant evaporates. As the refrigerant a of the compression refrigeration cycle 101, for example, ammonia can be used.

The steam cycle 103 includes a steam generation mechanism 11, an expander 12, a condenser 13, and a circulation pump 14 in the order of description in a circulation circuit in which the working medium circulates. A steam generating mechanism 11 for obtaining steam; an expander 12 for expanding the steam generated by the steam generating mechanism 11 to obtain a shaft output; and a condenser 13 for returning the working medium expanded by the expander 12 to liquid. The working medium that has become liquid by the condenser 13 is introduced into the steam generating mechanism 11 by the circulation pump 14. As the working medium b of the vapor cycle 103, for example, a mixed medium b in which the liquid to be absorbed absorbed by the absorbing liquid is water and the absorbing liquid is ammonia can be used. Here, as described above, the shaft output generated by the expander 12 is used for the operation of the high-pressure compressor 1b, but the output shaft of the expander 12 is directly connected to the drive shaft of the high-pressure compressor 1b. ing. When the expander side pressure of the shaft directly connecting the high pressure compressor 1b and the expander 12 is set lower than the compressor side pressure, ammonia leaks from the compression refrigeration cycle 102 side to the steam cycle 103 side. However, the working medium does not enter from the steam cycle 103 side to the compression refrigeration cycle 102 side. Such pressure setting can be realized by appropriately selecting the ammonia concentration of the mixed medium.
The above is the common configuration of the combined system 100 according to the present application. Hereinafter, the characteristic configuration of each embodiment will be mainly described with reference to each drawing.

[First Embodiment]
This embodiment is shown in FIG. As shown in the figure, in this example, a steam generator 11 a that generates steam of the working medium from exhaust heat held by the cooling water c is employed as the steam generation mechanism 11. This form is the most basic embodiment of the present application. Therefore, in this embodiment, all generated steam is sent to the expander 12.

[Second Embodiment]
This embodiment is shown in FIG. As shown in the figure, in this example, the steam generating mechanism 11 includes a regenerator 11b that regenerates the working medium b by exhaust heat recovered by the cooling water c of the prime mover 101, and a low level generated by the regenerator 11b. This is an example constituted by a separator 11c that separates into a concentrated solution and a high-concentrated vapor. A low-concentration solution (water ammonia solution having a low water concentration) is separated from the separator 11c through a low-concentration solution path 11d. The configuration in which the high-concentration steam (steam having a high water concentration) is sent to the expander 12 is adopted. This embodiment is an embodiment in which the characteristics of the mixed medium b can be used effectively.

[Third Embodiment]
This embodiment is shown in FIG. As shown in the figure, in this example, the refrigerant a sent from the low pressure compressor 1a to the high pressure compressor 1b is supplied from the liquid b of the working medium sent from the condenser 13 to the steam generation mechanism 11 and the steam generation mechanism 11. A first heat exchanger 15a and a second heat exchanger 15b are provided so as to exchange heat with both of the steam b traveling toward the expander 12. In this embodiment, the efficiency on the steam cycle 103 side is improved and the structure of the two-stage compression intermediate cooling is performed on the compression mechanism 1 side, so that the efficiency can also be improved.
In the case of this example, it is good also as a structure provided with either one of the 1st heat exchanger 15a and the 2nd heat exchanger 15b.

[Another embodiment]
(1) In the above embodiment, the exhaust heat recovered by the cooling water of the prime mover is used as the heat source of the steam cycle, but the steam cycle is operated using the heat of the exhaust gas discharged from the prime mover. It is good as well.
(2) In the above embodiment, an example is shown in which ammonia is used as the refrigerant for the compression refrigeration cycle, and a mixed medium of water ammonia is used as the working medium for the vapor cycle. Alcohol may be used, and a mixed medium of ethyl alcohol and water may be used as the working medium for the steam cycle.

The figure which shows the structure of 1st Embodiment. The figure which shows the structure of 2nd Embodiment. The figure which shows the structure of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 1a Low pressure compressor 1b High pressure compressor 2 Evaporator 3 Condenser 4 Expansion valve 11 Steam generation mechanism 11a Steam generator 11b Regenerator 11c Separator 12 Expander 13 Condenser 14 Circulation pump 15 Heat exchanger 100 Combined System 101 Motor 102 Compression refrigeration cycle 103 Steam cycle a Refrigerant b Working medium c Cooling water

Claims (3)

Refrigerant vapor generated in the evaporator is sequentially compressed by a low-pressure compressor and a high-pressure compressor, and the high-pressure refrigerant vapor generated by the high-pressure compressor is condensed in a condenser to form a refrigerant liquid, and the refrigerant liquid is expanded by an expansion valve. Provided with a compression refrigeration cycle that expands in the evaporator and evaporates in the evaporator to generate cold.
Provide a prime mover that generates shaft output,
A steam generation mechanism that obtains steam of a working medium by exhaust heat recovered from the prime mover, an expander that expands the steam generated by the steam generation mechanism to obtain a shaft output, and a working medium that has been expanded by the expander A steam cycle with a condenser to return the liquid to the liquid,
The low-pressure compressor is exerted by the shaft output of the prime mover,-out said high pressure compressor work by a shaft output of the expander,
The refrigerant circulating in the compression refrigeration cycle is ammonia, the working medium circulating in the vapor cycle is a mixed medium of ammonia and water,
A hybrid refrigerator in which an ammonia concentration of the working medium is set so that an expander-side pressure of a shaft directly connecting the high-pressure compressor and the expander is lower than a compressor-side pressure . A regenerator in which the working medium circulating in the steam cycle is a refrigerant solution circulating in the compression refrigeration cycle, and the steam generating mechanism regenerates the working medium by exhaust heat recovered by cooling water of the prime mover; The working medium regenerated by the regenerator is constituted by a separator that separates a low-concentration refrigerant solution and a high-concentration vapor,
The hybrid refrigerator according to claim 1, further comprising a low-concentration solution return path for returning the low-concentration solution to a condenser, wherein the high-concentration steam is sent to the expander. The refrigerant sent from the low-pressure compressor to the high-pressure compressor exchanges heat with the liquid of the working medium sent from the condenser to the steam generation mechanism, the steam from the steam generation mechanism toward the expander, or both. The hybrid refrigerator according to claim 1 or 2 , configured to be possible.

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