JP2002286310A - Compressive refrigerating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compressive refrigerating machine capable of increasing the air conditioning capacity, suppressing costs and facilitating maintenance work. SOLUTION: This compression refrigerating machine is provided with a first system (C1) with a compressor (3), an outdoor heat exchanger (5), a supercooling heat exchanger (7) and an indoor heat exchanger (10) interposed; and a second system (C2) having a compressor (13) and an outdoor heat exchanger (15) interposed and connected with the first system (C1) thermally through the supercooling heat exchanger (7). The refrigerant temperature at the outlet of the supercooling heat exchanger (7) in the second system (C2) is set higher than the refrigerant temperature at the outlet of the indoor heat exchanger (10) in the first system (C1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in efficiency of a compression refrigerator and an improvement in maintenance performance.

[0002]

2. Description of the Related Art In the prior art disclosed in Japanese Patent Application Laid-Open Nos. 6-129718 and 8-219580, as shown in FIG.
The electric compressor 13B is added to the air-conditioning system that drives B, and at the time of low-load operation in which the efficiency of the compressor system driven by the gas engine is reduced, the electric compressor system is operated alone to reduce the partial load. We are trying to improve efficiency. In addition, at the time of overload, both the gas engine and the electric motor are operated at the same time to increase the air conditioning capacity. But,
In the method according to the related art, there is a problem that it does not contribute to an improvement in efficiency under an operating condition with a high load factor that does not require switching to the independent operation of the electric compressor 13B.

In the prior art disclosed in JP-A-2000-111198, as shown in FIG. 12, a gas engine Eg, an electric motor 13B and a compressor 3B are connected to a clutch CL1.
And CL2 in series to achieve the same effect as the previous proposal. Further, a heat storage tank Ch is provided between the outdoor heat exchanger 5B and the indoor heat exchanger 10, and cold heat is stored in the heat storage tank Ch by driving the electric motor 13B using inexpensive midnight power, and heat is released as necessary. To improve efficiency. However, in this method, it is substantially difficult to stop the maintenance of the gas engine Eg while the electric motor 13B is operated, for example, from the viewpoint of maintaining safety of maintenance, and there is a problem in securing an installation cost and a place of the heat storage tank Ch. There is a problem.

[0004] In other words, the prior art which simultaneously satisfies the three points of "increase in air conditioning capacity", "cost reduction" and "easy maintenance" has not yet been proposed.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems of the prior art, and can increase the air-conditioning capacity, reduce costs, and facilitate maintenance work. The purpose of the present invention is to provide a compression refrigeration machine such as that described above.

[0006]

As a result of various studies, the present inventors have found that if the first system (C1) and the second system (C2) are provided, the excess refrigerant in the outlet of the condenser (5) of the main system is provided. By increasing the degree of cooling, efficiency can be improved under rated conditions or high load factors during cooling operation, and a sub-system (in charge of a super-cooling cycle) that provides a super-cooling heat source (in charge of a super-cooling cycle) Attention was paid to two points that, if the efficiency of C2) is improved, higher efficiency can be achieved as a whole.

[0007] The compression refrigerator of the present invention comprises: a compressor (3);
A first system (C1) including an outdoor heat exchanger (5), a subcooling heat exchanger (7), and an indoor heat exchanger (10).
A second system, which is provided with a compressor (13) and an outdoor heat exchanger (15) and is thermally connected to the first system (C1) via the supercooling heat exchanger (7). And the refrigerant temperature (for example, 20 ° C.) at the outlet of the subcooling heat exchanger (7) in the second system (C2) is the indoor heat exchanger (10) in the first system (C1). The temperature is set higher than the refrigerant temperature at the outlet (for example, 5 ° C.).

According to the present invention having the above-described configuration, the first system (C1) is provided with the supercooling heat exchanger (7), and the second system (C2) supplies the refrigerant. Allow to cool down. As is clear from FIG. 10 which is a Mollier diagram, this supercooling adds an area Aa on the left side of the isenthalpy line Ie, and increases the efficiency under the rated condition or the condition with a high load factor. Improve.

The refrigerant temperature (for example, 20 ° C.) at the outlet of the subcooling heat exchanger (7) in the second system (C2) depends on the refrigerant at the outlet of the indoor heat exchanger (10) in the first system (C1). The temperature is set higher than the temperature (for example, 5 ° C.). As a result, as shown in FIG.
By moving v upward, the width B indicating the required power is reduced (△ B), and the required power is greatly reduced with the same cooling capacity. Therefore, efficiency is improved. as a result,
Efficiency is improved as a whole of the first system (C1) and the second system (C2).

In implementing the present invention, the first system (C
The outdoor heat exchanger (5A) interposed in 1) is also used as the outdoor heat exchanger (5A) of the second system (D2), and the indoor heat exchanger (5A) of the first system (C1). 10) and the region (11) between the compressor (3A) and the second system (D
The region (18) between the subcooling heat exchanger (7) and the compressor (13A) in 2) is preferably connected by a line (19) provided with an on-off valve (20) ( Claim 2).

Normally, the on-off valve (20) is closed,
The first system (C1) and the second system (D2) are operated in parallel to maintain high-load operation. Then, the first system (C
During maintenance of the compressor (3A) in 1), the on-off valve (20) is opened and the line (19) is opened.
The indoor heat exchanger (10) of the first system (C1) is communicated with the compressor (13A) of the second system (D2). During maintenance of the compressor (3A) in the first system (C1), the circulation (refrigeration operation) of the refrigerant is continued by the compressor (13A) in the second system (D2). Second system (D2)
At the time of maintenance of the compressor (13A), the on-off valve (20) may be closed and the refrigerant may be circulated only in the first system (C1).

With this configuration, it is possible to continue the cooling operation even during maintenance. That is, maintainability is improved.

The driving of the compressors (3A and 13A) may be mechanical or electric, such as an internal combustion engine.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a compression refrigerator according to the present invention will be described below with reference to the drawings.

In FIG. 1, a compression refrigerator (hereinafter, abbreviated as a refrigerator) indicated by reference numeral 2 is composed of a first system C1 including a main compressor having a large capacity and a sub-compressor having a small capacity. , And a second system C2 including the second system C2.

The first system C1 includes a main compressor 3, an outdoor heat exchanger 5, a subcooling heat exchanger 7, and an indoor heat exchanger 1.
0, the main configuration.

The main compressor 3 and the outdoor heat exchanger 5 are communicated with each other by a pipe 4, and the outdoor heat exchanger 5 and the supercooling heat exchanger 7 are connected by a pipe 6.
It is communicated with.

The supercooling heat exchanger 7 and the indoor heat exchanger 10 are communicated by a pipe 7a via an expansion valve 8, and the indoor heat exchanger 7 and the main compressor 3 are communicated by a pipe 11. .

The second system C2 includes a sub-compressor 13 and an outdoor heat exchanger 15, and a subcooling heat exchanger 7
And is thermally connected to the first system C1 via the.

The sub-compressor 13 and the outdoor heat exchanger 15 communicate with each other through a pipe 14, and the outdoor heat exchanger 15 and the supercooling heat exchanger 7 communicate with each other via an expansion valve 17. The compressor 7 and the sub-compressor 13 are connected by a pipe 18.

The refrigerant temperature of the second system C2 to the subcooling heat exchanger 7 is determined by the outlet temperature of the subcooling heat exchanger 7 (for example, 2
0 ° C.) is set to be higher than the outlet temperature of the refrigerant of the indoor heat exchanger 10 (for example, 5 ° C.).

The operation of the above configuration is as follows. The refrigerant which has become high-pressure and high-temperature in the compressor 3 of the first system C1 is condensed in the outdoor heat exchanger 5 to become a saturated solution, and the second cooling is performed by the subcooling heat exchanger 7. The saturated solution refrigerant is supercooled by the expansion refrigerant of the system C2.

FIG. 10 is an example of a known Mollier diagram in which the vertical axis is pressure and the horizontal axis is enthalpy, and the area Aa on the left side of the isenthalpy line Ie is added by supercooling this saturated refrigerant solution. Thus, the efficiency is improved under the rated condition or the condition where the load factor is high.

The refrigerant supplied by the second system C2 is
At the outlet temperature of the subcooling heat exchanger 7 (for example, 20 ° C.), the outlet temperature of the indoor heat exchanger 10 of the first system C1 (for example, 5 ° C.)
Since the temperature is set higher than that, the isobar Ev indicating the cooling capacity on the lower side in the Mollier diagram in FIG. 10 is moved upward, and the width B indicating the required power is reduced (△ B). The required power is greatly reduced with the same cooling capacity. Therefore, the efficiency is improved, and the first system C1 and the second
As a whole, the efficiency of the system C2 is improved.

FIG. 2 shows an embodiment in which the above embodiment is compact and easy to implement. In FIG. 2, a refrigerator generally denoted by reference numeral 2A is a first system C1 including a main compressor 3A having a large capacity (for example, a mechanically driven compressor of the type driven by a gas engine; the same applies hereinafter) 3A, and a capacity thereof. And a second system D2 including a small sub-compressor 13A.

The first system C1 mainly includes a main compressor 3A, an outdoor heat exchanger 5A, a subcooling heat exchanger 7, and an indoor heat exchanger 10.

The main compressor 3A and the outdoor heat exchanger 5A are connected to the pipe 4
The outdoor heat exchanger 5A and the subcooling heat exchanger 7 are connected by a pipe 16.

The supercooling heat exchanger 7 and the indoor heat exchanger 10 are connected by a pipe 7a via an expansion valve 8, and the indoor heat exchanger 7 and the main compressor 3A are connected by a pipe 11. .

The second system D2 includes a sub-compressor (for example,
13A electric compressor driven by an electric motor
And the outdoor heat exchanger 5A of the first system C1 and the supercooling heat exchanger 7 of the first system C1 are shared and thermally connected.

The sub-compressor 13A is connected to the pipe 4 at a connection point B3 by a pipe 18a, and the pipe 4 is connected between the connection point B3 and the branch point B4.
Is shared with the system C1.

The branch point B4 is connected to the subcooling heat exchanger 7 via an expansion valve 17A, and the subcooling heat exchanger 7 and the sub-compressor 13A are connected to each other via a pipe 18 via a connection point B2. ing.

The junction B2 and the branch B1 of the first system C1
Is communicated with a line pipe 19 via an on-off valve 20.

The temperature of the refrigerant in the second system D2 to the subcooling heat exchanger 7 depends on the outlet temperature of the subcooling heat exchanger 7 (for example, 2
0 ° C.) is set to be higher than the outlet temperature of the refrigerant of the indoor heat exchanger 10 (for example, 5 ° C.).

FIG. 3 and FIG. 4 are explanatory views showing a state in which the refrigerator 2A having the above-described configuration is separately arranged in the indoor unit Ui and the outdoor unit Uo, and the flow of the refrigerant. I do.

The operation of the above-described configuration is performed when the main compressor 3 of the first system C1 and the sub-compressor 13A of the second system are simultaneously operated to perform a high load operation, and when the sub-compressor 13A is operated.
The description will be made separately for the case of only low load or the backup operation at the time of maintenance of the first system C1.

FIG. 3 shows a first system C1 and a second system D2.
Are operated at the same time to supercool the refrigerant in the first system C1 in the second system D2. In this case, the on-off valve 20 is closed.

In FIG. 3, a high-pressure, high-temperature refrigerant is cooled and condensed by an outdoor heat exchanger 5A by a main compressor 3A driven by a gas engine. The cooled and condensed refrigerant proceeds toward the indoor heat exchanger 10 via the pipe 16.

The refrigerant that has proceeded toward the indoor heat exchanger 10 is branched at the branch point B4, and a part thereof becomes the second system D2 and passes through the subcooling heat exchanger 16A via the expansion valve 17A. Then, the flow returns to the sub-compressor 13A via the pipe 18, the four-way valve 24, and the pipe 18A.

The other part, which is the refrigerant of the first system C1 branched at the branch point B4, passes through the subcooling heat exchanger 7 to the indoor heat exchanger 10.

In the above process, the refrigerant in the second system D2 expands to a low temperature via the expansion valve 17A, and the supercooling heat exchanger 7 supercools the refrigerant in the first system C1.

The supercooled refrigerant of the first system C1 expands at the expansion valve 8 to a low temperature, rises in temperature via the indoor heat exchanger 10, and returns to the main compressor 3A via the pipe 11. At this time,
Since the on-off valve 20 is closed, the refrigerant in the first system C1 does not mix through a different path from the second system D2.

FIG. 4 shows a state in which only the second system D2 is operated alone. In this case, the on-off valve 20 is open and the expansion valve 17A is closed. In FIG. 4, the refrigerant which has become high pressure and high temperature by the electric compressor 13A is cooled and condensed by the outdoor heat exchanger 5A. The cooled and condensed refrigerant proceeds toward the indoor heat exchanger 10 via the pipe 16.

Then, the temperature is expanded by the expansion valve 8 to a low temperature, the temperature is raised via the indoor heat exchanger 10, and the flow returns to the compressor 3A via the pipe 11.

In the process of passing the refrigerant to the compressor 3A through the pipe 11, the entire flow rate of the refrigerant is returned to the electric compressor 13A through the four-way valve 24 and the pipe 18A by opening the on-off valve 20.

Therefore, the compressor 3A can be stopped, and maintenance work of the compressor 3A in the maintenance work space Sm becomes possible.

When the sub-compressor 13A is to be maintained, the second system D2 can be stopped by closing the on-off valve 20 and the expansion valve 17 to operate the first system C1 alone.

The conditions for improving the cooling capacity and improving the COP (coefficient of performance) by the configuration of the refrigerator 2A are shown in FIGS.
Will be described.

In examining the COP, the main compressor 3
Alternatively, FIG. 10 shows a basic refrigeration cycle based on the single operation of 3A. And the isenthalpy line Ie in the figure
Is moved to the left, that is, the supercooling of the refrigerant improves the cooling capacity.

FIG. 5 shows that the isoenthalpy line Ie at 0 ° C. in FIG.
Is the state of the first system C1 that has moved to. In the refrigerating cycle, for example, the superheat degree at the inlet of the compressor is 15 ° C., and the outlet is 8 ° C.
2.8 ° C., evaporation 5 ° C., condensation 50 ° C.

FIG. 6 shows a refrigeration cycle of the second system C2 or D2 by operation of the sub-compressor 13 or 13A. The refrigerant in the first system C1 is supercooled on the basis of the isobar Ev1 at 20 ° C. evaporation.

FIG. 7 shows a calculation of energy per 1 kW of cooling capacity required to realize the refrigeration cycle shown in FIGS. 5 and 6. In the upper stage Gh, the first system C1 is connected to a compressor 3 or a gas engine (GHP). Each item for driving 3A is shown, and each item for driving the second system C2 or D2 by the electric (EHP) compressor 13 or 13A for supercooling is shown in the lower stage Eh.

The calculation results Rc for each item in the table and the details Pc thereof are described in the right column, and the total primary conversion COP is summarized at the bottom. In this result, the primary conversion C
OP is 1.006. The primary conversion coefficient of the electric power is 1 kW = 2450 kcal. FIG. 9 shows the gas engine used as the basis for the above calculation and the set efficiency Eff of electric power.

FIG. 8 shows Gb when the reference cycle of FIG. 10 is operated by a gas engine, GG when the first and second systems C1 and D2 are both operated by a gas engine, and the first and second systems C1 and D2 when the gas engine is operated. , The primary conversion COP is summarized for the gas engine and GE for electric operation. From this result, it is most efficient if the primary system C1 is operated by the gas engine, the secondary system D2 is electrically operated, and the specifications are as shown in FIG.

The illustrated embodiment is merely an example,
It is noted that the description is not to limit the technical scope of the present invention. For example, in the illustrated embodiment, the main compressor in the first system is constituted by a mechanical compressor driven by a gas engine, and the sub-compressor in the second system is constituted by an electric compressor driven by an electric motor. However, the type of compressor is not limited to this.

[0055]

The effects of the present invention are listed below. (1) According to the present invention, the main compressor of the first system and the second compressor
If the sub-compressor of the system is operated at the same time to increase the degree of supercooling of the refrigerant at the condenser outlet in the first system, the cooling capacity can be increased and the efficiency can be improved under the rated condition or the high load factor during the cooling operation. To be peeled off. (2) According to the present invention, at the time of low-efficiency low-load operation using only the main compressor of the first system, the single operation of only the sub-compressor of the second system is possible. (3) Maintenance of the main compressor in the first system can be performed safely while cooling operation is continued by sole operation of only the sub-compressor in the second system. Also, the second
In the case of maintenance of the sub-compressor of the first system, the cooling operation can be performed safely by continuing the cooling operation by operating only the main compressor of the first system.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a co-operating state of a main compressor (gas engine operation) and a sub-compressor (electric motor operation) in a second embodiment.

FIG. 4 is an explanatory diagram showing a state in which a main compressor (gas engine operation) is stopped and only a sub-compressor (electric motor operation) is operated in the second embodiment.

FIG. 5 is an example of a Mollier diagram when a main compressor and a sub-cooling sub-compressor cooperate.

6 is a Mollier diagram of a refrigeration cycle using the sub-cooler for supercooling in FIG.

FIG. 7 is an example of a trial calculation result of a coefficient of performance when the main compressor is operated by the gas engine and the sub-compressor is operated by the electric motor in order to realize the diagrams of FIGS. 5 and 6;

FIG. 8 is a comparison example of trial calculation results of coefficients of performance when the main compressor is operated by a gas engine and the sub-compressor is operated by a gas engine or an electric motor.

FIG. 9 shows specification values of the gas engine and the electric motor used in the calculation of FIGS. 7 and 8.

FIG. 10 is an example of a Mollier diagram when operated only by the main compressor.

FIG. 11 is a configuration diagram of a conventional system in which a main compressor is operated by a gas engine and a sub-compressor is operated by an electric motor.

FIG. 12 is a configuration diagram showing an example in which a heat storage tank is provided to improve thermal efficiency and cost efficiency in the conventional method.

[Explanation of symbols]

 C1 first system C2 second system 3 main compressor 5 outdoor heat exchanger 7 cooling heat exchanger 10 indoor heat exchanger 13 sub-compression Machine 15 outdoor heat exchanger 17 expansion valve

Claims (2)

[Claims] A first system including a compressor, an outdoor heat exchanger, a subcooling heat exchanger, and an indoor heat exchanger; a first system including a compressor and an outdoor heat exchanger; A second system that is thermally connected to the first system via a cooling heat exchanger, wherein the refrigerant temperature at the outlet of the supercooling heat exchanger in the second system is the indoor heat in the first system. A compression refrigerator having a temperature higher than the refrigerant temperature at the outlet of the exchanger. 2. An outdoor heat exchanger interposed in the first system is also used as an outdoor heat exchanger in the second system.
The area between the indoor heat exchanger of the first system and the compressor, and the area between the subcooling heat exchanger and the compressor of the second system,
2. The compression refrigerator according to claim 1, wherein the compressor is connected to a line provided with an on-off valve.