CN100419344C - air conditioner - Google Patents

Abstract

The air conditioner (1) has multiple utilization units (5), has a vapor compression refrigerant circuit (10) and a liquid receiver (25), and the vapor compression refrigerant circuit (10) includes: A high-pressure part (10a) constituted by a component that allows a high-pressure refrigerant of 3.3Mpa or greater to flow through, and a low-pressure part (10b) constituted by connecting a component that allows only a low-pressure refrigerant below the maximum operating pressure of 3.3MPa to flow through. ), the accumulator (25) is one of the parts that constitute the low-pressure part, and can store the refrigerant circulating in the refrigerant circuit as a liquid refrigerant, and the refrigerant flowing in the low-pressure part and the high-pressure part has a temperature higher than that of R407C Simulation of saturation pressure characteristics with azeotropic refrigerant mixtures, azeotropic refrigerant mixtures or single refrigerants. According to the present invention, in an air conditioner having a plurality of utilization units, even if the maximum operating pressure of the refrigerant circuit increases, an increase in the cost of components constituting the refrigerant circuit can be prevented.

Description

air conditioner

technical field

The invention relates to an air conditioner, in particular to an air conditioner with a plurality of utilization units.

Background technique

In air-conditioning apparatuses used for air conditioning of high-rise buildings, R407, which is an HFC-based refrigerant, is gradually being used as an operating refrigerant instead of R22 from the viewpoint of environmental protection.

Since this kind of air-conditioning device used for air conditioning of high-rise buildings has multiple utilization units, the operating load fluctuates greatly. With the fluctuation of operating load, the refrigerant circulation amount in the refrigerant circuit also fluctuates. In the refrigerant circuit An increase or decrease of the remaining refrigerant occurs. This surplus refrigerant is stored as liquid refrigerant in an accumulator connected to the suction side of the compressor.

However, if the remaining refrigerant is stored in storage, since R407 is a non-azeotropic mixed refrigerant, the evaporation process during the refrigeration cycle, that is, the evaporation process of the refrigerant in the heat exchanger on the utilization side of the utilization unit (during cooling operation) , or during the evaporation process of the refrigerant in the heat source side heat exchanger of the heat source unit (during heating operation), the composition of the refrigerant changes, and in the gas phase in the receiver, R32, a low boiling point component, becomes high in concentration state, in the liquid phase in the reservoir, R134a, a high-boiling point component, becomes a high-concentration state. Therefore, the refrigerant with a high concentration of R32 is sucked into the compressor and circulates in the refrigerant circuit, which may make the air conditioner as a whole unable to obtain the original performance of R407C.

To solve this problem, conventional air conditioners use bypass pipes to connect the accumulator and the refrigerant piping through which the high-pressure liquid refrigerant flows, to suppress changes in the composition of the refrigerant, or to detect the composition of the refrigerant to match the composition of the refrigerant. The most suitable operation control is carried out according to the change (refer to patent documents 1, 2, 3, 4.). In addition, there is another air conditioner that stores excess refrigerant in an accumulator connected to a refrigerant pipe through which high-pressure liquid refrigerant flows to suppress changes in refrigerant composition accompanying the evaporation process (see, for example, Patent Document 5).

Patent Document 1: JP-A-8-35725

Patent Document 2: Japanese Unexamined Patent Publication No. H10-220880

Patent Document 3: Japanese Unexamined Patent Publication No. H10-332211

Patent Document 4: Japanese Unexamined Patent Application Publication No. H11-173698

Patent Document 5: JP-A-2001-183020

In the former air conditioner using R407C, when the bypass pipe is used to connect the accumulator and the refrigerant piping through which the high-pressure liquid refrigerant flows, the configuration and operation control of the refrigerant circuit become complicated.

On the other hand, when the latter type of air conditioner using R407C is connected to the refrigerant piping through which the pressurized liquid refrigerant flows by using a receiver instead of an accumulator, the configuration and operation of the refrigerant circuit are different from those of the former type. The control is not complicated, which is its advantage.

However, recently, in the field of air-conditioning devices used for air-conditioning of high-rise buildings, in order to improve air-conditioning performance and reduce the size of the machine, a refrigerant using a saturation pressure higher than R407C (such as R410A or HC-based refrigeration) has also been developed and produced. agent) products. However, when using a refrigerant with a saturated pressure higher than R407C, compared with when using R407C, since the maximum operating pressure of the refrigerant flowing in the refrigerant circuit (mostly about 1 MPa higher than the standard operating pressure, hereinafter referred to as the maximum Use pressure) rises, so it is necessary to increase the compressive strength of the components constituting the refrigerant circuit. In particular, in air conditioners used in high-rise buildings, the parts constituting the refrigerant circuit are larger in size compared to smaller air conditioners such as household air conditioners, so the portion of the refrigerant circuit through which high-pressure refrigerant flows (hereinafter referred to as the high-pressure portion) Since the maximum working pressure also increases, the compressive strength of the parts constituting the refrigerant circuit has to be increased, which tends to increase the cost. Therefore, in an air conditioner including the above-mentioned accumulator as one of the components of the high-pressure section, in order to increase the pressure resistance of the accumulator, the thickness of the accumulator must be increased, resulting in an increase in cost.

Contents of the invention

The object of the present invention is to suppress the cost of components constituting the refrigerant circuit even if the maximum operating pressure of the refrigerant circuit increases due to the use of a refrigerant with a saturation pressure higher than R407C in an air conditioner having a plurality of utilization units Increase.

The air conditioner of claim 1 has a plurality of utilization units, and has a vapor compression refrigerant circuit and an accumulator. The vapor compression refrigerant circuit includes: a high-pressure part connected with components that allow a high-pressure refrigerant with a maximum operating pressure of 3.3Mpa or greater to flow through, and a low-pressure refrigeration unit that is only allowed to allow a maximum operating pressure of 3.3MPa. The low-pressure part is composed of components through which the agent flows. The accumulator is one of components constituting the low-pressure portion, and stores the refrigerant circulating in the refrigerant circuit as liquid refrigerant. The refrigerant flowing in the low-pressure part and the high-pressure part is a pseudo-azeotropic mixed refrigerant, an azeotropic mixed refrigerant, or a single refrigerant.

In the case of using R407C as the operating refrigerant of the air conditioner, the standard working pressure of the high pressure part is about 2.0MPa. Therefore, in an air conditioner using R407C as an operating refrigerant, the maximum operating pressure of the high pressure part is often 3.0 to 3.3 MPa which is about 1 MPa higher than the standard operating pressure of 2.0 MPa. Therefore, in an air conditioner using R407C as an operating refrigerant, the parts constituting the high pressure section only need to have a compressive strength capable of withstanding 3.3 MPa.

On the other hand, if a refrigerant with a saturation pressure higher than R407C is used, the maximum working pressure of the high pressure part will exceed 3.3MPa, so the components constituting the high pressure part are required to have a pressure resistance of 3.3MPa or more. In particular, containers and pipes are not manufactured with the most suitable wall thickness calculated from the maximum working pressure of the high-pressure part, but are usually selected from JIS and other standards with a wall thickness that satisfies the maximum working pressure conditions. The material is processed. Therefore, using a refrigerant with a saturation pressure higher than R407C will greatly increase the wall thickness, and the cost of configuring the refrigerant circuit will increase more than necessary.

In order to prevent the above unnecessary cost increase, the air conditioner of the present invention adopts simulated azeotropic mixed refrigerant, azeotropic mixed refrigerant or single refrigerant as the refrigerant whose saturation pressure is higher than R407C, and at the same time, the maximum operating pressure is lower than 3.3MPa The low-pressure part is equipped with an accumulator that can store the surplus refrigerant that increases or decreases with the fluctuation of the operating load of multiple utilization units, so there is no need to install a receiver in the high-pressure part, and there is no need to install anti-refrigeration as when using non-azeotropic mixed refrigerants Parts such as bypass pipes with changing agent composition.

In this way, even if the maximum operating pressure of the refrigerant circuit increases due to the use of a refrigerant having a saturation pressure higher than that of R407C, an increase in the cost of components constituting the refrigerant circuit can be prevented.

According to claim 2, in the air conditioner according to claim 1, the refrigerant flowing through the low-pressure part and the high-pressure part contains R32.

According to claim 3, in the air conditioner according to claim 1, the refrigerant flowing through the low-pressure part and the high-pressure part is R410A.

The air conditioner of technical solution 4 has: a compressor that compresses low-pressure gas refrigerant to discharge high-pressure gas refrigerant; a heat source side heat exchanger that can work as an evaporator and a condenser; and a plurality of utilization-side heat exchangers in which the evaporator operates; an expansion mechanism connected between the utilization-side heat exchangers and the heat source-side heat exchanger; a switching mechanism capable of switching between the following states: namely, connecting the gas side of the heat source side heat exchanger to the discharge side of the compressor, and connecting the suction side of the compressor to the gas side of the utilization side heat exchanger to suck low pressure gas refrigerant state of the compressor, and connecting the gas side of the heat source side heat exchanger to the suction side of the compressor, and connecting the discharge side of the compressor to the gas side of the utilization side heat exchanger, to A state in which high-pressure gas refrigerant flows into the utilization-side heat exchanger; an accumulator connected between the switching mechanism and the suction side of the compressor, capable of storing low-pressure refrigerant as liquid refrigerant, includes The liquid accumulator and the low-pressure part formed by connecting the switching mechanism to the suction side of the compressor only allow low-pressure refrigerant lower than the maximum operating pressure of 3.3MPa to flow through, as a part other than the low-pressure part , the high-pressure part formed by connecting the compressor, the heat source side heat exchanger, the plurality of utilization side heat exchangers and the switching mechanism can flow through a high pressure refrigeration unit with a maximum operating pressure of 3.3Mpa or greater. The refrigerant flowing in the low-pressure part and the high-pressure part is a simulated azeotropic mixed refrigerant, an azeotropic mixed refrigerant or a single refrigerant with a saturation pressure characteristic higher than that of R407C.

In the case of using R407C as the operating refrigerant of the air conditioner, the standard working pressure of the high pressure part is about 2.0MPa. Therefore, in an air conditioner using R407C as an operating refrigerant, the maximum operating pressure of the high pressure part is often 3.0 to 3.3 MPa which is about 1 MPa higher than the standard operating pressure of 2.0 MPa. Therefore, in an air conditioner using R407C as an operating refrigerant, the parts constituting the high pressure section only need to have a compressive strength capable of withstanding 3.3 MPa.

On the other hand, if a refrigerant with a saturation pressure higher than R407C is used, the maximum working pressure of the high pressure part will exceed 3.3MPa, so the components constituting the high pressure part are required to have a pressure resistance of 3.3MPa or more. In particular, containers and pipes are not manufactured with the most suitable wall thickness calculated from the maximum working pressure of the high-pressure part, but are usually selected from JIS and other standards with a wall thickness that satisfies the maximum working pressure conditions. The material is processed. Therefore, using a refrigerant with a saturation pressure higher than R407C will greatly increase the wall thickness, and the cost of configuring the refrigerant circuit will increase more than necessary.

In order to prevent the above unnecessary cost increase, the air conditioner of the present invention adopts simulated azeotropic mixed refrigerant, azeotropic mixed refrigerant or single refrigerant as the refrigerant whose saturation pressure is higher than R407C, and at the same time, the maximum operating pressure is lower than 3.3MPa The low-pressure part is equipped with an accumulator that can store the surplus refrigerant that increases or decreases with the fluctuation of the operating load of multiple utilization units, so there is no need to install a receiver in the high-pressure part, and there is no need to install anti-refrigeration as when using non-azeotropic mixed refrigerants Parts such as bypass pipes with changing agent composition.

In this way, even if the maximum operating pressure of the refrigerant circuit increases due to the use of a refrigerant having a saturation pressure higher than that of R407C, an increase in the cost of components constituting the refrigerant circuit can be prevented.

Claim 5 is the air conditioner of Claim 4, further comprising: a heat source side temperature detector for detecting the temperature of the liquid-side refrigerant in the heat source-side heat exchanger; The temperature detector on the utilization side of the refrigerant temperature, the high pressure detector for detecting the pressure of the refrigerant on the discharge side of the compressor, and the temperature detector on the heat source side, the temperature detector on the utilization side and the high pressure pressure detector The detected refrigerant temperature and refrigerant pressure value are used to adjust the opening of the expansion mechanism so that the liquid refrigerant on the liquid side of the heat source side heat exchanger become a predetermined supercooled state, and adjust the opening degree of the expansion mechanism so that the liquid refrigerant on the liquid side of the use-side heat exchanger becomes a predetermined supercooled state when the use-side heat exchanger operates as a condenser. cooling state.

In this air conditioner, when the heat source side heat exchanger is operated as a condenser as in the cooling operation, by making the condensed refrigerant into a predetermined supercooled state, the excess refrigerant that increases or decreases with the change of the operating load can be reliably recovered. stored in the reservoir. In addition, even when the use-side heat exchanger is operated as a condenser as in the heating operation, by making the condensed refrigerant into a predetermined supercooled state, it is possible to reduce the excess refrigerant that increases or decreases due to changes in the operating load. Reliably stored in the reservoir.

According to claim 6, in any one of the air conditioners according to claims 4 to 5, the refrigerant flowing through the low-pressure part and the high-pressure part contains R32.

Since this air conditioner uses R32 refrigerant with high heat transfer capability, it can improve the air conditioning capability.

Claim 7 is any one of the air conditioners in Claims 4 to 5, wherein the refrigerant flowing through the low-pressure part and the high-pressure part is R410A.

Since this air conditioner uses R410A, it can further improve the air conditioning capacity compared with R407C.

Description of drawings

Fig. 1 is a schematic refrigerant circuit diagram of an air conditioner according to Embodiment 1 of the present invention.

Fig. 2 is a Molière diagram illustrating a refrigeration cycle of an air conditioner.

Figure 3 is a graph showing the relationship between operating pressure and wall thickness.

Detailed ways

(1) The overall structure of the air conditioner

Fig. 1 is a schematic refrigerant circuit diagram of an air conditioner according to Embodiment 1 of the present invention. Air conditioner 1 is the device that can be used for cooling and heating of high-rise building etc., and this air conditioner has: heat source unit 2, a plurality of (being 2 in this embodiment) utilization units 5 that are connected in parallel with it, connect heat source unit 2 and utilize Liquid refrigerant piping 6 and gas refrigerant piping 7 for the unit 5 .

In the air conditioner 1 related to this example, a pseudo azeotropic mixture refrigerant R410A (R32: 50 wt%, R125: 50 wt%) whose saturation pressure is higher than R407C is used as an operating refrigerant. In R410A, since the content of R32 with high heat transfer capability is higher than R407C, the air conditioning capability of the air conditioner 1 can be improved.

(2) Configuration of the use unit

The usage unit 5 is mainly composed of a usage-side expansion valve 51 , a usage-side heat exchanger 52 , and piping connecting them.

The usage-side expansion valve 51 is an electric expansion valve for adjusting refrigerant pressure and refrigerant flow rate in this embodiment, and is connected to the liquid side of the usage-side heat exchanger 52 .

In this embodiment, the utilization-side heat exchanger 52 serves as a refrigerant evaporator to cool indoor air during cooling operation, and serves as a refrigerant condenser to heat indoor air during heating operation. In addition, a usage-side temperature detector 53 for detecting the temperature of the refrigerant is provided on the usage-side heat exchanger 52 . In this embodiment, the usage-side temperature detector 53 is a thermistor arranged on the liquid side of the usage-side heat exchanger 52 .

(3) Composition of heat source unit

The heat source unit 2 is mainly composed of a compressor 21, a four-way switching valve 22, a heat source side heat exchanger 23, a heat source side expansion valve 24, a liquid reservoir 25, a liquid side isolation valve 26, a gas side isolation valve 27, and piping connecting them. constitute.

In this embodiment, the compressor 21 is a variable capacity compressor that compresses low-pressure gas refrigerant and discharges high-pressure gas refrigerant. In addition, a high-pressure pressure detector 28 constituted by a pressure sensor for detecting the pressure of the high-pressure gas refrigerant is provided on the discharge side of the compressor 21 .

The four-way switching valve 22 is used to switch the flow direction of the refrigerant when switching between the cooling operation and the heating operation. The suction side of the machine 21 (specifically, the accumulator 25) is connected to the gas refrigerant connection pipe 7 side (refer to the solid line of the four-way switching valve 22 in FIG. 1 ), and the four-way switching valve 22 Connect the discharge side of the compressor 21 to the gas refrigerant connection pipe 7 side, and connect the suction side of the compressor 21 to the gas side of the heat source side heat exchanger 23 (refer to the dotted line of the four-way switching valve 22 in FIG. 1 ) .

In this embodiment, the heat source side heat exchanger 23 functions as a condenser for refrigerant using outdoor air or water as a heat source during cooling operation, and as an evaporator for refrigerant using outdoor air or water as a heat source during heating operation. . In addition, a heat source side temperature detector 29 for detecting the temperature of the refrigerant is provided on the heat source side heat exchanger 23 . In this embodiment, the heat source side temperature detector 29 is a thermistor arranged on the liquid side of the heat source side heat exchanger 23 .

The heat source side expansion valve 24 is connected to the liquid side of the heat source side heat exchanger 23 , and in this embodiment, is an electric expansion valve for adjusting the refrigerant flow rate between the heat source side heat exchanger 23 and the utilization side heat exchanger 52 .

The accumulator 25 is connected between the four-way switching valve 22 and the compressor 21 and is a container for storing low-pressure refrigerant sucked into the compressor 21 and surplus refrigerant.

The liquid side isolation valve 26 and the gas side isolation valve 27 are connected to the liquid refrigerant connection pipe 6 and the gas refrigerant connection pipe 7 , respectively. The liquid refrigerant connection pipe 6 connects the liquid side of the use side heat exchanger 52 of the use unit 5 and the liquid side of the heat source side heat exchanger 23 of the heat source unit 2 . The gas refrigerant connection pipe 7 connects the gas side of the use-side heat exchanger 52 of the use unit 5 and the four-way switching valve 22 of the heat source unit 2 .

The utilization-side expansion valve 51, utilization-side heat exchanger 52, compressor 21, four-way switching valve 22, heat-source-side heat exchanger 23, heat-source-side expansion valve 24, accumulator 25, liquid-side isolation valve 26, and gas-side The refrigerant circuit in which the isolation valves 27 are sequentially connected serves as the refrigerant circuit 10 of the air conditioner 1 .

(3) Operation of the air conditioner

The operation of the air conditioner 1 under standard use conditions will be described below using FIGS. 1 and 2 . Figure 2 is a Molière diagram illustrating the refrigerating cycle of an air conditioner.

<During cooling operation>

During cooling operation, the state of the four-way switching valve 22 is shown by the solid line in Fig. The gas side of the side heat exchanger 52 is connected. In addition, the liquid-side isolation valve 26 and the gas-side isolation valve 27 are opened, and the utilization-side expansion valve 51 is fully opened. The heat source side expansion valve 24 is in a state where the opening can be adjusted by supercooling control between the high pressure detector 28 and the heat source side temperature detector 29 . To be more specific, the high pressure is calculated based on the temperature difference between the saturation temperature corresponding to the high pressure gas refrigerant pressure value detected by the high pressure pressure detector 28 and the high pressure liquid refrigerant temperature value detected by the heat source side heat exchanger 29. The degree of subcooling of the liquid refrigerant is adjusted, and the opening degree of the expansion valve 24 on the heat source side is adjusted so that the degree of subcooling becomes a predetermined value.

In the state of the refrigerant circuit 10, when the compressor 21 is activated, the low-pressure gas refrigerant (pressure Ps = about 0.9 MPa, temperature Ts = about 15°C) is sucked into the compressor 21 and compressed into a high-pressure gas refrigerant (pressure Pd=approximately 3.0 MPa, temperature Td=approximately 70° C.) (see points A and B in FIG. 2 ). Thereafter, the high-pressure gas refrigerant is sent into the heat source side heat exchanger 23 through the four-way switching valve 22, exchanges heat with the outdoor air or water as the heat source, and is condensed to cool down the saturation temperature Tsat( temperature about 50° C.) slightly lower temperature Tc (about 45° C.) (see point C in FIG. 2 ). Here, the subcooling degree ΔTc (ie, Tsat-Tc) of the high-pressure liquid refrigerant in the point C state is kept constant by the subcooling control of the heat source side expansion valve 24 (here, ΔTc=about 5° C.).

Then, the condensed liquid refrigerant is decompressed into a low-pressure gas-liquid two-phase refrigerant (pressure Ps = about 0.9 MPa, temperature TD = about 3° C.) according to the opening degree of the heat source side expansion valve 24 (see Fig. 2), and sent to the utilization unit 5 through the liquid side isolation valve 26 and the liquid refrigerant connection pipe 6.

The gas-liquid two-phase refrigerant sent to the utilization unit 5 passes through the utilization-side expansion valve 51, exchanges heat with the indoor air in the utilization-side heat exchanger 52 and is evaporated, and becomes a low-pressure gas refrigerant again (pressure Ps=approx. 0.9 MPa, temperature Ts = about 15°C) (see point A in Fig. 2). This low-pressure gas refrigerant flows into the accumulator 25 through the gas refrigerant connecting pipe 7 , the gas side isolation valve 27 , and the four-way switching valve 22 . The low-pressure gas refrigerant flowing into the accumulator 25 is sucked into the compressor 21 again.

As described above, the supercooling control of the heat source side expansion valve 24 keeps the degree of supercooling ΔTc of the high-pressure liquid refrigerant at point C constant. Therefore, even if the operating load of the utilization unit 5 fluctuates and the refrigerant circulation amount changes, It is also possible to ensure a state change like the refrigeration cycle shown in FIG. 2 and to store excess refrigerant in the accumulator 25 .

In addition, when the low-pressure liquid refrigerant flows into the accumulator 25 from the use-side heat exchanger 52 together with the low-pressure gas refrigerant, or when the surplus refrigerant is stored in the accumulator 25, the low-pressure gas refrigerant is discharged in the accumulator 25. The gas-liquid separation between the low-pressure liquid refrigerant and only the low-pressure gas refrigerant is sucked into the compressor 21 . At this time, since this embodiment uses R410A, one of the simulated azeotropic mixed refrigerants, as the operating refrigerant, the gas-liquid separation in the accumulator 25 can make the refrigerant of the low-pressure gas refrigerant sucked into the compressor 21 The composition remains the same as that of the liquid refrigerant stored in the accumulator 25 .

<During heating operation>

During heating operation, the state of the four-way switching valve 22 is shown by the dotted line in FIG. The gas side of the heat exchanger 23 is connected. In addition, the liquid side isolation valve 26 and the gas side isolation valve 27 are opened, and the heat source side expansion valve 24 is fully opened. The utilization-side expansion valve 51 is in a state where the opening can be adjusted by supercooling control of the high-pressure pressure detector 28 and the utilization-side temperature detector 53 . To be more specific, according to the temperature difference between the saturation temperature corresponding to the high-pressure gas refrigerant pressure value detected by the high-pressure pressure detector 28 and the high-pressure liquid refrigerant temperature value detected by the utilization side heat exchanger 53, the high pressure The degree of subcooling of the liquid refrigerant is adjusted, and the opening degree of the expansion valve 51 on the utilization side is adjusted so that the degree of subcooling becomes a predetermined value.

In the state of the refrigerant circuit 10, if the compressor 21 is started, the low-pressure gas refrigerant is sucked into the compressor 21 and compressed into a high-pressure gas refrigerant, and then passes through the four-way switching valve 22, the gas-side isolation valve 27 and the gas refrigerant. The agent connection pipe 7 is sent to the utilization unit 5 . Then, the high-pressure gas refrigerant sent to the utilization unit 5 exchanges heat with indoor air in the utilization-side heat exchanger 52 to be condensed and cooled to a temperature slightly lower than the saturation temperature of the high-pressure gas refrigerant. Here, the degree of subcooling of the high-pressure liquid refrigerant in the point C state remains constant due to the subcooling control of the use-side expansion valve 51 . The condensed liquid refrigerant is depressurized according to the opening of the use side expansion valve 51 to become a low-pressure gas-liquid two-phase refrigerant, and is sent to the heat source unit 2 through the liquid refrigerant connection pipe 6 and the liquid side isolation valve 26 . The gas-liquid two-phase refrigerant sent to the heat source unit 2 passes through the heat source side expansion valve 24, then exchanges heat with the outdoor air or water as the heat source in the heat source side heat exchanger 23, and is evaporated to become a low-pressure gas refrigerant again. , and flows into the accumulator 25 through the four-way switching valve 22 . And, the low-pressure gas refrigerant flowing into the accumulator 25 is sucked into the compressor 21 again.

As mentioned above, during the heating operation, the flow direction of the refrigerant is opposite to that during the cooling operation, and the supercooling control is performed by using the side expansion valve 51. Except for these two points, the state change of the refrigerant is the same as that shown in FIG. 2 The state change of the refrigeration cycle is the same.

(4) Design pressure of components constituting the refrigerant circuit

It can be seen from the operation descriptions of the above-mentioned air conditioner 1 during cooling operation and heating operation that the refrigerant circuit 10 is composed of the refrigerant circuit part through which the high-pressure refrigerant flows, that is, the high-pressure part 10a and the refrigerant circuit part through which only the low-pressure refrigerant flows. , That is, the low pressure part 10b is formed. Specifically, the low-pressure part 10b is a part connecting the four-way switching valve 22 including the accumulator 25 to the suction side of the compressor 21, and the high-pressure part 10a is a part of the refrigerant circuit 10 excluding the low-pressure part 10b.

Here, the components constituting the high pressure part 10a (specifically, the compressor 21, the four-way switching valve 22, the heat source side heat exchanger 23, the heat source side expansion valve 24, the liquid side isolation valve 26, the gas side isolation valve 27, The use-side expansion valve 51 and the use-side heat exchanger 52) and piping leave a margin of about 1 MPa for the standard operating pressure (about 3.0 MPa) of the above-mentioned high-pressure refrigerant, so that the high-pressure refrigerant with the highest operating pressure (about 4 MPa) The agent can flow through the above-mentioned parts and piping. In addition, for the components (specifically, the accumulator 25) and the piping that constitute the low-pressure part 10b, a margin of about 1 MPa is left for the standard operating pressure (about 0.9 MPa) of the above-mentioned low-pressure refrigerant, so that the maximum operating pressure ( Low-pressure refrigerant of about 2MPa) can flow through the above-mentioned components and piping.

(5) Features of the air conditioner

The air conditioner 1 of this embodiment has the following features.

(A) Since the air conditioner 1 of the present embodiment uses R410A whose saturation pressure is higher than R407C as the refrigerant, at the same time, the low-pressure part 10b with the maximum operating pressure lower than 3.3MPa is provided with a storage unit that can store the operating load accompanying a plurality of utilization units 5. The accumulator 25 of the excess refrigerant that increases or decreases due to fluctuations, so the high pressure part 10a does not need to be provided with a receiver.

Therefore, even if the maximum operating pressure of the refrigerant circuit increases due to the use of a refrigerant having a saturation pressure higher than R407C, the air conditioner 1 can suppress an increase in the cost of components constituting the refrigerant circuit.

With regard to the effect of suppressing the increase in cost, the case where R410A is used as the refrigerant causes the maximum working pressure of the refrigerant circuit to rise. 10a is compared with the case where a receiver (not shown) is installed.

For example, when using JIS standard product STPG370E (carbon steel pipe for pressure piping) as a material to process and manufacture a cylindrical reservoir 25 and a receiver with a nominal diameter of 10 inches, consider selecting a schedule 20 (thickness 6.4mm) ) or size 30 (wall thickness 7.8mm). Moreover, as shown in the relationship between operating pressure and wall thickness in Figure 3, the material of specification 30 can be used up to 4.3MPa.

Here, since the maximum working pressure of the accumulator 25 is about 2.0 MPa (the maximum working pressure of the low-pressure part 10b), even if the material of specification 20 is used, it has sufficient compressive strength and can be selected. On the other hand, since the maximum working pressure of the receiver is about 4.0MPa (the maximum working pressure of the high-pressure part 10a), the material of specification 20 cannot be used, and although the wall thickness of about 7.4mm is sufficient from the calculation point of view, But you must choose a material with a specification of 30.

When R407C is used as the operating refrigerant of the air conditioner, since the maximum operating pressure of the high pressure part is between 3.0 and 3.3 MPa, the material of specification 20 can be used. However, when R410A is used as in this example, the saturation pressure is higher than that of R407C If the receiver is used as a container for storing the remaining refrigerant, the wall thickness will be greatly increased, which will increase the unnecessary cost of the components constituting the refrigerant circuit. In other words, as described above, when using a refrigerant such as R410A whose saturation pressure is higher than R407C, using an accumulator instead of a receiver as a container for storing the remaining refrigerant can prevent cost increases.

(B) In addition, since R410A is a simulated azeotropic mixed refrigerant, even if the accumulator 25 is used as a container for storing the remaining refrigerant, it is not necessary to prevent changes in the composition of the refrigerant as when using a non-azeotropic mixed refrigerant such as R407C. Bypass pipes and other components can prevent an increase in the cost of components that make up the refrigerant circuit.

(C) During the cooling operation of the air conditioner 1, the temperature difference between the pressure value of the high-pressure gas refrigerant detected by the high-pressure pressure detector 28 and the temperature value of the high-pressure liquid refrigerant detected by the heat source side heat exchanger 29 , calculate the degree of subcooling of the high-pressure liquid refrigerant, and adjust the opening of the heat source side expansion valve 24 so that the degree of subcooling becomes a specified value, so that the excess refrigerant that increases or decreases with changes in the operating load can be reliably stored in the Inside the reservoir 25. In addition, during heating operation, the high-pressure refrigerant can be calculated based on the temperature difference between the pressure value of the high-pressure gas refrigerant detected by the high-pressure pressure detector 28 and the temperature value of the high-pressure liquid refrigerant detected by the use-side heat exchanger 53 . The degree of subcooling of the liquid refrigerant is adjusted, and the opening of the expansion valve 51 on the utilization side is adjusted so that the degree of subcooling becomes a specified value, so that the excess refrigerant that increases or decreases with changes in the operating load can be reliably stored in the accumulator. within 25.

(6) Other embodiments

The embodiments of the present invention have been described above with reference to the drawings. However, the specific configuration is not limited to the above embodiments, and can be changed within the scope not departing from the gist of the invention.

(A) The air conditioner in the foregoing embodiments has a refrigerant circuit capable of cooling and heating operations, but it is not limited to this, and an air conditioner with a refrigerant circuit dedicated to cooling or dedicated to heating without a four-way switching valve is also available. The same applies to the present invention.

(B) In the aforementioned embodiments, R410A, one of the simulated azeotropic mixed refrigerants, is used as the operating refrigerant, but it is not limited thereto, R32: R125 such as R410B (R32: 45wt%, R125: 55wt%) can also be used A simulated azeotropic mixed refrigerant whose composition ratio is different from R410A or a single refrigerant such as R32, other simulated azeotropic mixed refrigerants or an azeotropic mixed refrigerant.

Possibility of industrial use

According to the present invention, in an air conditioner having a plurality of utilization units, even if the maximum operating pressure of the refrigerant circuit increases due to the use of a refrigerant with a saturation pressure higher than R407C, an increase in the cost of components constituting the refrigerant circuit can be prevented .

Claims (7)

1. an aircondition (1) has a plurality of unit (5) that utilize,

It is characterized in that having steam compression type refrigeration agent loop (10) and reservoir (25),

Steam compression type refrigeration agent loop (10) comprises: being connected with and can allowing maximum working (operation) pressure (MWP) is that the high-voltage section (10a) that constitutes of parts that 3.3Mpa or bigger high-pressure refrigerant flow through and being connected with only allows to be lower than the low voltage section (10b) that parts that the low pressure refrigerant of maximum working (operation) pressure (MWP) 3.3MPa flows through constitute

Reservoir (25) is one of parts that constitute described low voltage section, the cold-producing medium that circulates in described refrigerant loop can be stored as liquid refrigerant,

In described low voltage section and the mobile cold-producing medium of described high-voltage section is simulation azeotropic refrigerant, azeotropic refrigerant or the unitary system cryogen with the saturation pressure characteristic that is higher than R407C.

2. aircondition as claimed in claim 1 (1) is characterized in that, comprises R32 in described low voltage section (10b) and the mobile cold-producing medium of described high-voltage section (10a).

3. aircondition (1) according to claim 1 is characterized in that, is R410A in described low voltage section (10b) and the mobile cold-producing medium of described high-voltage section (10a).

4. an aircondition (1) has:

With the low-pressure refrigerant gas compression, to discharge the compressor (21) of high-pressure gas refrigerant;

Can be used as the heat source side heat exchanger (23) of evaporimeter and condensed device work;

Connect, can be used as a plurality of side heat exchangers (52) that utilize of condensed device and evaporator operation mutually side by side;

Be connected in the described expansion mechanism (24,51) that utilizes between side heat exchanger and the described heat source side heat exchanger;

The switching mechanism (22) that can between following state, switch: promptly, the gas side of described heat source side heat exchanger is connected with the discharge side of described compressor, and the suction side of described compressor is connected with the described gas side of side heat exchanger that utilizes, low-pressure refrigerant gas being sucked the state of compressor, and the gas side of described heat source side heat exchanger is connected with the suction side of described compressor, and the discharge side of described compressor is connected with the described gas side of side heat exchanger that utilizes, so that high-pressure gas refrigerant flows into the described state that utilizes the side heat exchanger;

Be connected between the suction side of described switching mechanism and described compressor, can be with the cold-producing medium of low pressure reservoir (25) as the liquid refrigerant storage,

Comprise described reservoir and flow through with the low pressure refrigerant that the low voltage section (10b) that constitutes after the suction side of described compressor is connected only allows to be lower than maximum working (operation) pressure (MWP) 3.3MPa by described switching mechanism,

As the part beyond the described low voltage section, can flow through maximum working (operation) pressure (MWP) by described compressor, described heat source side heat exchanger, described a plurality of high-voltage section (10a) that constitute after utilizing side heat exchanger and described switching mechanism to connect is 3.3Mpa or bigger high-pressure refrigerant

The cold-producing medium that is flowing in described low voltage section and described high-voltage section is simulation azeotropic refrigerant, azeotropic refrigerant or the unitary system cryogen with the saturation pressure characteristic that is higher than R407C.

5. aircondition as claimed in claim 4 (1), it is characterized in that, also have: detect the hydraulic fluid side refrigerant temperature of described heat source side heat exchanger (23) heat source side Temperature Detector (29), detect utilizing side Temperature Detector (53), detecting the high-pressure detector (28) of the discharge side refrigerant pressure of described compressor (21) of the described hydraulic fluid side refrigerant temperature of respectively utilizing side heat exchanger (52)

According to described heat source side Temperature Detector, described side Temperature Detector and detected refrigerant temperature of described high-pressure detector and the refrigerant pressure value utilized, regulate the aperture of described expansion mechanism (24), when described heat source side heat exchanger is worked as condensed device, to make the liquid refrigerant of described heat source side heat exchanger hydraulic fluid side become predetermined supercooling state, and regulate the aperture of described expansion mechanism (51), to make the described liquid refrigerant of side heat exchanger hydraulic fluid side that utilizes become predetermined supercooling state when utilizing the side heat exchanger to work as condensed device described.

6. as claim 4 or 5 described airconditions (1), it is characterized in that, comprise R32 in described low voltage section (10b) and the mobile cold-producing medium of described high-voltage section (10a).

7. as aircondition (1) as described in claim 4 or 5, it is characterized in that, is R410A in described low voltage section (10b) and the mobile cold-producing medium of described high-voltage section (10a).

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