Air-conditioning system

Abstract

The present specification relates to an embodiment of an air-conditioning system using a plurality of turbo compressors, wherein driving of the plurality of turbo compressors is switched according to operating conditions, and multiple injections are made into an internal heat exchanger, thereby circulating a refrigerant in response to the operating conditions.

Description

air conditioning system

[0001] The present invention relates to an air conditioning system using a plurality of turbocompressors.

[0002] Large-capacity chillers (600 [RT] or more) typically used for commercial and industrial purposes are water-cooled and utilize oil-free turbocompressors with gas bearings based on the cold cycle. Due to the nature of turbocompressors, they typically have a mechanism with one or two impellers. When two impellers are used, they can operate in a higher compression ratio range than systems with a single impeller, and their two-stage compression / single injection technology enables year-round, high-efficiency operation.

[0003] As an example of the prior art, U.S. Patent Publication No. US 10794619 B2 (hereinafter referred to as the prior art) discloses a large-capacity chiller system having a cooling capacity of 600 [RT] or more. The chiller system of the prior art is a 2-stage turbo compressor having a single-stage impeller and a double-stage impeller and a communicating pipe through which refrigerant can flow between the two impellers, and a two-stage compression / single injection cycle is performed, and injection is performed by an economizer located between the primary expansion valve at the rear end of the condenser and the secondary expansion valve at the front end of the evaporator (the pressure after the first expansion is induced as an intermediate pressure).

[0004] Normal operation of a two-stage compression single injection cycle technology of a phase separator type such as the above-mentioned prior art can be achieved as illustrated in Fig. 1. In the case of the above-mentioned prior art, it is necessary to control the area (resistance, opening) of the 1 / 2 expansion valves before and after the phase separator to always maintain a higher intermediate pressure than the intermediate pressure at the outlet of the 1st stage of the compressor. However, since the intermediate pressure changes very sensitively to the adjustment of the area of ​​the 1 / 2 stage expansion device, there is a problem of a high possibility of control deviation. In particular, the possibility of control deviation increases further when abrupt impeller rotation speed adjustment occurs due to the initial start-up of the compressor or load response and reliability control. If the intermediate pressure on the phase separator side becomes lower than the intermediate pressure of the compressor, the following problems are likely to occur.

[0005] 1) As shown in Figure 2, if the primary compressed medium-temperature and medium-pressure refrigerant of the compressor flows back and flows into the phase separator side, the possibility of a decrease in performance (cooling capacity and efficiency) due to a decrease in the refrigerant flow rate on the evaporator side increases.

[0006] 2) If the pressure drop in the first expansion chamber is insufficient, that is, if the refrigerant flowing into the phase separator after the first expansion is 100% liquid, the liquid refrigerant in the phase separator increases and overflow occurs, and the liquid refrigerant flows into the upper gaseous refrigerant discharge port. If it flows into the suction end of the second-stage impeller of the compressor, as shown in Fig. 3, the possibility of damage to the second-stage impeller due to liquid or wet compression increases. In addition, the possibility of bearing damage increases due to the increase in the thrust difference between the first and second-stage impellers due to a sudden decrease in the refrigerant flow rate flowing into the first-stage impeller due to a temporary lack of cycle refrigerant.

[0007] In addition, the above prior art applies two separate circuits for cooling the inside of the turbo compressor. In this case, since some of the refrigerant compressed and condensed to high pressure using energy through the two circuits is bypassed for compressor cooling, the amount of refrigerant that must be bypassed increases, which causes a decrease in the refrigerant flow rate flowing into the evaporator, resulting in a decrease in performance (cooling capacity and efficiency). In addition, if the cooling circuit for cooling the inside of the turbo compressor uses the refrigerant at the condenser outlet, when the compressor is stopped and restarted in a state of equal pressure, the possibility of compressor failure due to wear of various bearings in the internal mechanical parts of the compressor increases due to the delay in refrigerant flow due to the physical distance from the compressor discharge port to the condenser outlet.

[0008] In addition, when a system such as the above prior art is expanded to an air-cooled heat pump system of 150 [RT] or less, a lower low pressure and evaporation temperature or a higher high pressure and condensation temperature are required to absorb or dissipate heat in an outdoor heat exchanger, and at this time, the conditions for operation outside the operating map range according to the high compression ratio increase, and accordingly, performance (cooling capacity and efficiency) is lowered due to reliability control (hot gas bypass, etc.), and a stable supply of cooling capacity becomes impossible due to unstable cycle operation.

[0009] In particular, when the heat dissipation part is changed from water-cooling to air-cooling, the refrigerant condensation temperature must be increased to secure the same heat dissipation amount due to the decrease in the heat transfer performance of the air, and the difference between the refrigerant condensation temperature and the air intake temperature must be increased to about 15℃. Accordingly, the possibility of a surging phenomenon occurring as shown in Fig. 4 increases due to the increase in compression ratio caused by the increase in high pressure.

[0010] In addition, when restarting the compressor in a balanced pressure state after stopping the compressor, the reliability of the compressor mechanism is lowered due to a delay in the supply of refrigerant to the gas bearing, which increases the possibility of compressor failure. In addition, there is a limitation that the possibility of compressor reliability is higher because refrigerant backflow or wet compression frequently occurs depending on the intermediate pressure of the phase separator.

[0011] [Prior Art Literature]

[0012] [Patent Document]

[0013] (Patent Document 1) US 10794619 B2

[0014] The present invention aims to improve the limitations of the prior art as described above.

[0015] Accordingly, the present specification provides an embodiment in which an air-cooled heat pump system of 150 [RT] or less can be operated stably, efficiently, and with high performance.

[0016] Specifically, the present invention aims to provide an example of an air-cooled heat pump oil-free turbo chiller that can achieve stable operation and high efficiency in all four seasons by applying internal heat exchanger type multi-injection technology and high-reliability compressor cooling technology.

[0017] In addition, the present invention aims to provide an embodiment in which two compressors perform serial compression during a cooling overload period when the outside temperature rises in the summer, thereby enabling surge avoidance and high cooling performance operation through four-stage compression dual injection.

[0018] In addition, the present invention aims to provide an embodiment that enables year-round high-efficiency heating and cooling operation through vapor refrigerant bypass through an evaporator front-end phase separator.

[0019] In addition, the present invention aims to provide an embodiment that improves the reliability of a gas bearing system through rapid refrigerant transfer when restarting from a balanced pressure state after a stop, and enables high-efficiency operation of the gas bearing system with refrigerant superheated to a medium temperature through an internal heat exchanger for the gas bearing at the condenser outlet and inverter refrigerant cooling during continuous operation.

[0020] The present invention, which aims to solve the above-described problem, is characterized in that it switches the operation of a plurality of turbo compressors according to the operating conditions and allows multiple injections to be performed through an internal heat exchanger, thereby allowing the refrigerant to circulate in response to the operating conditions.

[0021] An embodiment of an air conditioning system that uses the above technical features as a means for solving a problem includes a plurality of turbocompressors that compress refrigerant in two stages, a first four-way valve that switches the flow path of refrigerant flowing into or discharged from the plurality of turbocompressors depending on whether the plurality of turbocompressors are driven in series or in parallel, a second four-way valve that switches the flow path of the refrigerant depending on whether the plurality of turbocompressors are driven in cooling operation, heating operation, or defrosting operation, an outdoor heat exchanger that is connected to at least one of the plurality of turbocompressors and performs heat exchange of the refrigerant, an outdoor expansion valve that is connected to the outdoor heat exchanger and performs expansion of the delivered refrigerant, a plurality of internal heat exchangers that are connected to the outdoor expansion valves and performs heat exchange of the refrigerant, an indoor expansion valve that is connected to the plurality of internal heat exchangers and performs expansion of the delivered refrigerant, an indoor phase separator that is connected to the indoor expansion valves and separates phases of the delivered refrigerant, and a shell-and-tube heat exchanger that is connected to the phase separator and the plurality of turbocompressors and performs heat exchange of the delivered refrigerant, wherein the plurality of turbocompressors, the first four-way valve, and the second four-way valve are configured to operate in the cooling operation, The operation is different depending on the operating conditions, such as whether the heating operation or the defrosting operation is performed and the outdoor temperature condition, so that the refrigerant circulates differently depending on the operating conditions.

[0022] Here, during the cooling operation or the defrosting operation, the outdoor heat exchanger performs heat exchange of refrigerant delivered from at least one of the plurality of turbocompressors, the outdoor expansion valve performs expansion of refrigerant delivered from the outdoor heat exchanger, the plurality of internal heat exchangers perform heat exchange of refrigerant delivered from the outdoor expansion valve, the indoor expansion valve performs expansion of refrigerant delivered from the plurality of internal heat exchangers, the indoor phase separator separates the phase of the refrigerant delivered from the indoor expansion valve and delivers the separated gaseous refrigerant to the plurality of turbocompressors, and the shell-and-tube heat exchanger performs heat exchange of liquid refrigerant delivered from the phase separator and delivers the heat-exchanged refrigerant to the plurality of turbocompressors.

[0023] Here, during the heating operation, the outdoor heat exchanger performs heat exchange of the refrigerant to be delivered to at least one of the plurality of turbocompressors, the outdoor expansion valve performs expansion of the refrigerant to be delivered to the outdoor heat exchanger, the plurality of internal heat exchangers perform heat exchange of the refrigerant to be delivered to the outdoor expansion valve, the indoor expansion valve performs expansion of the refrigerant to be delivered to the plurality of internal heat exchangers, the indoor phase separator separates the phase of the refrigerant to be delivered to the indoor expansion valve and delivers it, and the shell-and-tube heat exchanger can perform heat exchange of the refrigerant to be delivered to the phase separator.

[0024] In an embodiment, the plurality of turbocompressors may have different capacities.

[0025] In an embodiment, the plurality of turbocompressors may have a capacity of one that is less than or equal to 50 [%] of the capacity of another.

[0026] In an embodiment, the first four-way valve includes a first valve stage connected to an inlet of a first stage of one of the plurality of turbocompressors, a second valve stage connected to an inlet of each of the plurality of turbocompressors, a third valve stage connected to a discharge of a second stage of the one compressor, and a fourth valve stage connected to an inlet of the outdoor heat exchanger, and may open and close each of the first to fourth valve stages, or connect any two or more of them.

[0027] In an embodiment, the second four-way valve may include a first valve stage connected to the discharge ports of each of the two stages of the plurality of turbo compressors, a second valve stage connected to the discharge port of the shell-and-tube heat exchanger, a third valve stage connected to the inlet port of the accumulator of the plurality of turbo compressors, and a fourth valve stage connected to the inlet port of the outdoor heat exchanger, and may open and close each of the first valve stage to the fourth valve stage, or connect any two or more of them.

[0028] In an embodiment, the system may further include an outdoor phase separator disposed between the outdoor heat exchanger and the outdoor expansion valve, which separates the phase of the refrigerant delivered from the outdoor expansion valve during the heating operation and delivers the separated refrigerant in a gaseous state to the plurality of turbocompressors.

[0029] In an embodiment, the plurality of indoor heat exchangers include a first indoor heat exchanger, a second indoor heat exchanger, and a third indoor heat exchanger arranged in series, and each of the first to third indoor heat exchangers includes an inlet valve that opens and closes an inlet portion, so that refrigerant received from a previous heat exchanger can undergo heat exchange in one or more indoor heat exchangers according to operation of the inlet valve.

[0030] In an embodiment, the first indoor heat exchanger is such that the inlet valve can exchange heat with the refrigerant during all of the cooling operation, the heating operation, and the defrosting operation.

[0031] In an embodiment, when heat exchange is performed in the first indoor heat exchanger, a cooler may be further included to cool the refrigerant vaporized in the first indoor heat exchanger and deliver it to the first stage inlet of each of the plurality of turbocompressors.

[0032] In an embodiment, when the above-described operation corresponds to the cooling operation and the temperature state is 27 [℃] or higher, the first four-way valve may switch the flow path so that the second-stage discharge port of one compressor among the plurality of turbo compressors and the first-stage inlet port of the other compressor are connected, and the inlet port of the outdoor heat exchanger and the discharge port of the shell-and-tube heat exchanger are connected, and the second four-way valve may switch the flow path so that the discharge port of the shell-and-tube heat exchanger and the inlet port of the accumulation of the plurality of turbo compressors are connected, and the second-stage discharge port of the other compressor and the inlet port of the outdoor heat exchanger are connected.

[0033] In an embodiment, when the above-described operation corresponds to the above-described cooling operation and the above-described temperature state is 27 [℃] or higher, the plurality of turbocompressors can compress the refrigerant in the order of the first and second stages of the one compressor, the first and second stages of the other compressor, and deliver the refrigerant compressed in four stages from the second-stage discharge port of the other compressor to the outdoor heat exchanger.

[0034] In an embodiment, when the above-described operation corresponds to the above-described cooling operation and the above-described temperature state is 27 [℃] or higher, the plurality of indoor heat exchangers may each have their respective inlet valves opened to perform heat exchange, but one of them, which is positioned in the middle, may transfer the vaporized refrigerant to the first-stage inlet of the other compressor, and one of them, which is positioned before the indoor expansion valve, may transfer the vaporized refrigerant to the second-stage inlet of the first compressor.

[0035] In an embodiment, when the above-described operation corresponds to the cooling operation and the temperature state is less than 27 [℃], the first four-way valve may switch the flow path so that the discharge port of the second stage of one compressor among the plurality of turbocompressors and the inlet port of the outdoor heat exchanger are connected, and the inlet port of the first stage of the one compressor and the inlet port of the first stage of the other compressor are connected, and the second four-way valve may switch the flow path so that the discharge port of the shell-and-tube heat exchanger and the inlet port of the accumulation of the plurality of turbocompressors are connected, and the discharge port of the second stage of the other compressor and the inlet port of the outdoor heat exchanger are connected.

[0036] In an embodiment, when the above-described operation corresponds to the above-described cooling operation and the above-described temperature state is less than 27 [℃], the plurality of turbocompressors can compress the refrigerant in the first and second stages, respectively, of the one compressor and the other compressor, and deliver the refrigerant compressed in two stages from the second-stage discharge portion of the one compressor and the second-stage discharge portion of the other compressor to the outdoor heat exchanger.

[0037] In an embodiment, when the above-described operation corresponds to the above-described cooling operation and the above-described temperature state is less than 27 [℃], the inlet valves of each of the two heat exchangers arranged at both ends of the plurality of indoor heat exchangers are opened so that heat exchange occurs in each of the two heat exchangers, and one of the two heat exchangers arranged before the indoor expansion valve can transfer the vaporized refrigerant to each of the second-stage inlet of the first compressor and the second-stage inlet of the other compressor.

[0038] In an embodiment, when the operation corresponds to the heating operation, the first four-way valve switches the flow path so that the second stage discharge port of one compressor among the plurality of turbo compressors and the first stage inlet port of the other compressor are connected, and the inlet port of the outdoor heat exchanger and the discharge port of the shell-and-tube heat exchanger are connected, and the second four-way valve switches the flow path so that the inlet port of the outdoor heat exchanger and the inlet ports of the accumulations of the plurality of turbo compressors are connected, and the second stage discharge port of the other compressor and the discharge port of the shell-and-tube heat exchanger are connected, so that the refrigerant can circulate in a direction opposite to the direction during the cooling operation.

[0039] In an embodiment, when the above operation corresponds to the heating operation, the plurality of turbo compressors can compress the refrigerant in the order of the first and second stages of the one compressor, the first and second stages of the other compressor, and deliver the refrigerant compressed in four stages from the second stage discharge port of the other compressor to the shell-and-tube heat exchanger.

[0040] In an embodiment, when the above operation corresponds to the heating operation, the plurality of indoor heat exchangers may each have their respective inlet valves opened to perform heat exchange, but one of them, positioned in the middle, may transfer the vaporized refrigerant to the first stage inlet of the other compressor, and one of them, positioned before the indoor expansion valve, may transfer the vaporized refrigerant to the second stage inlet of the first compressor.

[0041] In an embodiment, when the above-described operation corresponds to the defrost operation, the first four-way valve may switch the flow path so that the discharge port of the second stage of one compressor among the plurality of turbocompressors and the inlet port of the outdoor heat exchanger are connected, and the inlet port of the first stage of the one compressor and the inlet port of the first stage of the other compressor are connected, and the second four-way valve may switch the flow path so that the discharge port of the shell-and-tube heat exchanger and the inlet port of the accumulation of the plurality of turbocompressors are connected, and the discharge port of the second stage of the other compressor and the inlet port of the outdoor heat exchanger are connected.

[0042] In an embodiment, when the above-described operation corresponds to the above-described defrost operation, the plurality of turbocompressors can compress the refrigerant in the first and second stages, respectively, of the one compressor and the other compressor, and deliver the refrigerant compressed in two stages from the second-stage discharge portion of the one compressor and the second-stage discharge portion of the other compressor to the outdoor heat exchanger.

[0043] In an embodiment, when the above driving corresponds to the above-described operation, the plurality of indoor heat exchangers may have the inlet valves of heat exchangers adjacent to the outdoor heat exchanger opened so that heat exchange can take place in the adjacent heat exchangers.

[0044] Embodiments of the air conditioning system as described above are not limited to those described above, and may include embodiments described in the specific description to be described below or embodiments that can be inferred / derived from the specific description.

[0045] According to the embodiment of the air conditioning system described above, by applying the internal heat exchanger type multi-injection technology and the high-reliability compressor cooling technology, it is possible to achieve stable operation and high-efficiency operation in all four seasons.

[0046] Additionally, during the cooling overload period when the outside temperature rises in the summer, two compressors perform serial compression, which has the effect of avoiding surge and achieving high cooling performance through four-stage compression dual injection.

[0047] In addition, there is an effect that enables year-round high-efficiency cold operation through gaseous refrigerant bypass through the evaporator front-end phase separator.

[0048] In addition, the refrigerant circuit of the compressor's gas bearing system is dualized, which has the effect of improving the reliability of the gas bearing system through rapid refrigerant transfer when restarting from a balanced pressure state after stopping.

[0049] In addition, during continuous operation, the gas bearing system can be operated with high efficiency by using the refrigerant superheated to a medium temperature through the internal heat exchanger for the gas bearing at the condenser outlet and the inverter refrigerant cooling.

[0050] The effects according to the embodiment of the air conditioning system described above are not limited to those described above, and may also include effects described in the specific description to be described below or effects that can be inferred / derived from the specific description.

[0051] Figures 1 to 3 are diagrams showing driving results according to conventional prior art.

[0052] Figure 4 is a graph showing the operation map of a turbo compressor.

[0053] Fig. 5 is a configuration diagram of an air conditioning system according to an embodiment.

[0054] Fig. 6 is a specific configuration diagram of the air conditioning system shown in Fig. 5.

[0055] Figure 7 is an example diagram showing a specific operation example of the air conditioning system illustrated in Figure 6.

[0056] Fig. 8 is a diagram showing the driving results according to the driving example illustrated in Fig. 7.

[0057] Figure 9 is an example diagram 2 showing a specific operation example of the air conditioning system illustrated in Figure 6.

[0058] Fig. 10 is a diagram showing the driving results according to the driving example illustrated in Fig. 9.

[0059] Figure 11 is an example diagram showing a specific operation example of the air conditioning system illustrated in Figure 6.

[0060] Fig. 12 is a diagram showing the driving results according to the driving example illustrated in Fig. 11.

[0061] Figure 13 is an example diagram showing a specific operation example of the air conditioning system illustrated in Figure 6.

[0062] Fig. 14 is a diagram showing the driving results according to the driving example illustrated in Fig. 13.

[0063] Hereinafter, an air conditioning system according to an embodiment will be described in detail with reference to the attached drawings. However, in order to clearly describe the features of the present invention, descriptions of contents corresponding to general technical matters in the relevant technical field or some components may be omitted.

[0064] An embodiment of the air conditioning system (hereinafter referred to as the air conditioning system) of this specification may be a chiller system.

[0065] The above air conditioning system may be a system of 150 [RT] or less.

[0066] The above air conditioning system may be an air-cooled or water-cooled heat pump system.

[0067] The above air conditioning system may be an air-cooled heat pump system that operates in one of cooling operation, heating operation, and defrosting operation.

[0068] The above air conditioning system (100), as shown in FIG. 5, includes a compression unit (10), a valve unit (20), an external heat exchange unit (30), an internal heat exchange unit (40), an expansion unit (50), a phase separation unit (60), and a shell-and-tube heat exchange unit (70).

[0069] A pipe for the flow of refrigerant may be provided between each of the compression unit (10), the valve unit (20), the external heat exchange unit (30), the internal heat exchange unit (40), the expansion unit (50), the phase separation unit (60), and the shell-and-tube heat exchange unit (70).

[0070] Accordingly, in the air conditioning system (100), the refrigerant may be circulated in the order of the compression unit (10), the external heat exchange unit (30), the internal heat exchange unit (40), the expansion unit (50), the phase separation unit (60), and the shell-and-tube heat exchange unit (70), or in the order of the compression unit (10), the shell-and-tube heat exchange unit (70), the phase separation unit (60), the expansion unit (50), the internal heat exchange unit (40), and the external heat exchange unit (30).

[0071] In the above air conditioning system (100), during cooling operation, the refrigerant may circulate in the order of the compression unit (10), the valve unit (20), the external heat exchange unit (30), the internal heat exchange unit (40), the expansion unit (50), the phase separation unit (60), and the shell-and-tube heat exchange unit (70), and during heating operation, the refrigerant may circulate in the order of the compression unit (10), the shell-and-tube heat exchange unit (70), the phase separation unit (60), the expansion unit (50), the internal heat exchange unit (40), the external heat exchange unit (30), and the valve unit (20).

[0072] The above compression unit (10) may include a plurality of compressors (11, 12) that compress the refrigerant.

[0073] The above compressor (11, 12) may be a turbo compressor that compresses the refrigerant in two stages.

[0074] The above compression unit (10) may preferably include two turbo compressors (11, 12), in which case the two turbo compressors (11, 12) may be connected in series or parallel.

[0075] The above compression unit (10) may further include an accumulator (13) that separates / converts the phase of the refrigerant supplied to the plurality of turbo compressors (11, 12).

[0076] Accordingly, the refrigerant flowing into each of the plurality of turbo compressors (11, 12) can be introduced after being phase separated / converted through the accumulator (13).

[0077] The above compression unit (10) can be connected at one end to the external heat exchange unit (30) and at the other end to the shell-and-tube heat exchange unit (70).

[0078] That is, the compression unit (10) may be connected at one end to a pipe connected to the external heat exchange unit (30), and at the other end to a pipe connected to the shell-and-tube heat exchange unit (70).

[0079] Accordingly, the compression unit (10) may receive refrigerant from the shell-and-tube heat exchange unit (70), compress it, and transfer the compressed refrigerant to the external heat exchange unit (30), or receive refrigerant from the external heat exchange unit (30), compress it, and transfer the compressed refrigerant to the shell-and-tube heat exchange unit (70).

[0080] For example, during the cooling operation or the defrosting operation, the refrigerant may be received from the shell and tube heat exchanger (70), compressed, and the compressed refrigerant may be transferred to the external heat exchanger (30).

[0081] In this case, the external heat exchange unit (30) may correspond to a condensation unit, and the shell-and-tube heat exchange unit (70) may correspond to an evaporation unit.

[0082] In addition, during the heating operation, the refrigerant may be received from the external heat exchanger (30), compressed, and the compressed refrigerant may be transferred to the shell-and-tube heat exchanger (70).

[0083] In this case, the external heat exchange unit (30) may correspond to an evaporation unit, and the shell-and-tube heat exchange unit (70) may correspond to a condensation unit.

[0084] The above valve unit (20) may include a plurality of four-way valves (21, 21) that switch the flow path of the refrigerant.

[0085] The above valve unit (20) may include a first four-way valve (21) that switches the flow path of refrigerant flowing into or discharged from the plurality of turbo compressors (11, 12).

[0086] The above first four-way valve (21) can switch the flow path of the refrigerant by connecting or opening and closing the four valve stages depending on whether the plurality of turbo compressors (11, 12) are driven in series or in parallel.

[0087] The above valve unit (20) may include a second four-way valve (22) that switches the flow path of the refrigerant depending on whether the cooling operation, the heating operation, or the defrosting operation is in progress.

[0088] The above second four-way valve (22) can switch the flow path of the refrigerant by connecting or opening and closing the four valve stages depending on whether the cooling operation, the heating operation or the defrosting operation is in progress.

[0089] The above external heat exchange unit (30) can have one end connected to the internal heat exchange unit (40) and the other end connected to the compression unit (10).

[0090] That is, the external heat exchange unit (30) may be connected at one end to a pipe connected to the internal heat exchange unit (40), and at the other end to a pipe connected to the compression unit (10).

[0091] Accordingly, the external heat exchange unit (30) may receive refrigerant from the compression unit (10), perform heat exchange, and then transfer the heat-exchanged refrigerant to the internal heat exchange unit (40), or may receive refrigerant from the internal heat exchange unit (40), perform heat exchange, and then transfer the heat-exchanged refrigerant to the compression unit (10).

[0092] For example, during the cooling operation or the defrosting operation, the refrigerant may be transferred from the compression unit (10) and heat exchanged, and then the heat-exchanged refrigerant may be transferred to the internal heat exchange unit (40).

[0093] In addition, during the heating operation, the refrigerant may be transferred from the internal heat exchange unit (40) and heat exchanged, and then the heat-exchanged refrigerant may be transferred to the compression unit (10).

[0094] The above external heat exchanger (30) may include an outdoor heat exchanger (31) in which heat exchange of the refrigerant transferred from the compression unit (10) takes place.

[0095] The above outdoor heat exchanger (31) is installed outdoors, and heat exchange of the refrigerant transferred from the plurality of turbo compressors (11, 12) or the internal heat exchanger (40) can be performed.

[0096] The above external heat exchanger (30) may include an outdoor expansion valve (32) in which expansion of the transmitted refrigerant occurs.

[0097] The above outdoor expansion valve (32) is installed outdoors, and expansion of the refrigerant transmitted from the outdoor heat exchanger (31) or the internal heat exchanger (40) can be achieved.

[0098] The above external heat exchanger (30) may also include an outdoor phase separator (33) that separates the phase of the delivered refrigerant.

[0099] The above outdoor phase separator (33) is installed outdoors and can separate the phase of the refrigerant delivered from the outdoor expansion valve (32) or the internal heat exchanger (40).

[0100] The above internal heat exchanger (40) may include a plurality of indoor heat exchangers (41, 42, 43) installed indoors and through which heat exchange of the refrigerant transferred from the external heat exchanger (30) is performed.

[0101] The above internal heat exchanger (40) may preferably include three or more indoor heat exchangers (41, 42, 43), and in this case, the three or more indoor heat exchangers (41, 42, 43) may be connected in series.

[0102] The internal heat exchanger (40) may have one end connected to the expansion unit (50) and the other end connected to the external heat exchanger (30).

[0103] That is, the internal heat exchange unit (40) may be connected at one end to a pipe connected to the expansion unit (50), and at the other end to a pipe connected to the external heat exchange unit (30).

[0104] Accordingly, the internal heat exchange unit (40) may receive refrigerant from the external heat exchange unit (30), perform heat exchange, and then transfer the heat-exchanged refrigerant to the expansion unit (50), or may receive refrigerant from the expansion unit (50), perform heat exchange, and then transfer the heat-exchanged refrigerant to the external heat exchange unit (30).

[0105] For example, during the cooling operation or the defrosting operation, refrigerant may be transferred from the external heat exchanger (30) and heat exchange may be performed, and then the heat-exchanged refrigerant may be transferred to the expansion unit (50).

[0106] In addition, during the heating operation, the refrigerant may be transferred from the expansion unit (50) and heat exchanged, and then the heat-exchanged refrigerant may be transferred to the external heat exchange unit (30).

[0107] The above expansion unit (50) may include an indoor expansion valve installed indoors, through which the refrigerant delivered from the internal heat exchange unit (40) or the phase separation unit (60) expands.

[0108] The above expansion part (50) can have one end connected to the phase separation part (60) and the other end connected to the internal heat exchange part (40).

[0109] That is, the expansion unit (50) can be connected at one end to a pipe connected to the phase separation unit (60) and at the other end to a pipe connected to the internal heat exchange unit (40).

[0110] Accordingly, the expansion unit (50) may receive refrigerant from the internal heat exchange unit (40), expand, and then transfer it to the phase separation unit (60), or receive refrigerant from the phase separation unit (60), expand, and then transfer it to the internal heat exchange unit (40).

[0111] For example, during the cooling operation or the defrosting operation, the refrigerant may be transferred from the internal heat exchange unit (40) and then transferred to the phase separation unit (60).

[0112] In addition, during the heating operation, the refrigerant may be delivered from the phase separation unit (60) and then delivered to the internal heat exchange unit (40).

[0113] The above phase separation unit (60) may include a phase separator that separates the phase of the refrigerant delivered from the expansion unit (50) or the shell-and-tube heat exchange unit (70).

[0114] The above-mentioned phase separation unit (60) can be connected at one end to the shell-and-tube heat exchange unit (70) and the compression unit (10), and at the other end to the expansion unit (50).

[0115] That is, the above-mentioned phase separation unit (60) can be connected at one end to a pipe connected to the shell-and-tube heat exchange unit (70) and the compression unit (10), and at the other end to a pipe connected to the expansion unit (50).

[0116] Accordingly, the phase separation unit (60) can separate the phase of the refrigerant delivered from the expansion unit (50) and deliver the separated gaseous refrigerant to the compression unit (10), or separate the phase of the refrigerant delivered from the shell-and-tube heat exchange unit (70) and deliver the separated gaseous refrigerant to the expansion unit (50).

[0117] For example, during the cooling operation or the defrosting operation, the phase of the refrigerant delivered from the expansion unit (50) can be separated, and the separated gaseous refrigerant can be delivered to the compression unit (10).

[0118] In addition, during the heating operation, the phase of the refrigerant transferred from the shell and tube heat exchanger (70) can be separated, and the separated gaseous refrigerant can be transferred to the expansion unit (50).

[0119] The above shell-and-tube heat exchanger (70) may include one or more shell-and-tube heat exchangers (71) installed indoors and in which heat exchange of the refrigerant transferred from the phase separation unit (60) or the compression unit (10) is performed.

[0120] The above shell and tube heat exchanger (70) can have one end connected to the compression unit (10) and the other end connected to the phase separation unit (60).

[0121] That is, the shell and tube heat exchanger (70) may be connected at one end to a pipe connected to the compression section (10) and at the other end to a pipe connected to the phase separation section (60).

[0122] Accordingly, the shell and tube heat exchange unit (70) may perform heat exchange of the liquid refrigerant transferred from the phase separation unit (60) and transfer the heat-exchanged refrigerant to the compression unit (10), or may perform heat exchange of the refrigerant transferred from the compression unit (10) and transfer the heat-exchanged refrigerant to the phase separation unit (60).

[0123] For example, during the cooling operation or the defrosting operation, heat exchange of the liquid refrigerant transferred from the phase separation unit (60) may be performed, and the heat-exchanged refrigerant may be transferred to the compression unit (10).

[0124] In addition, during the heating operation, heat exchange of the refrigerant transferred from the compression unit (10) may be performed, and the heat-exchanged refrigerant may be transferred to the phase separation unit (60).

[0125] The air conditioning system (100) in which refrigerant circulation is performed, including the compression unit (10), the valve unit (20), the external heat exchange unit (30), the internal heat exchange unit (40), the expansion unit (50), the phase separation unit (60), and the shell-and-tube heat exchange unit (70), can be implemented with a configuration as shown in FIG. 6.

[0126] The air conditioning system (100), as shown in FIG. 6, comprises: a plurality of turbo compressors (11, 12) for compressing refrigerant in two stages; a first four-way valve (21) for switching the flow path of refrigerant flowing into or discharged from the plurality of turbo compressors (11, 12) depending on whether the plurality of turbo compressors (11, 12) are driven in series or in parallel; a second four-way valve (22) for switching the flow path of refrigerant depending on whether the plurality of turbo compressors (11, 12) are driven in cooling operation, heating operation, or defrosting operation; an outdoor heat exchanger (31) connected to at least one of the plurality of turbo compressors (11, 12) and performing heat exchange of refrigerant; an outdoor expansion valve (32) connected to the outdoor heat exchanger (31) and performing expansion of the delivered refrigerant; a plurality of internal heat exchangers (41, 42, 43) connected to the plurality of internal heat exchangers (41, 42, 43) and performing heat exchange of the delivered refrigerant; It includes an indoor expansion valve (50) in which expansion takes place, an indoor phase separator (61) connected to the indoor expansion valve (50) to separate the phases of the delivered refrigerant, and a shell-and-tube heat exchanger (71) connected to the phase separator (61) and the plurality of turbo compressors (11, 12) to perform heat exchange of the delivered refrigerant.

[0127] In the air conditioning system (100), the plurality of turbo compressors (11, 12), the first four-way valve (21) and the second four-way valve (22) operate differently depending on the operating conditions, such as whether the cooling operation, the heating operation or the defrosting operation is in progress and the outdoor temperature condition, so that the refrigerant circulates differently depending on the operating conditions.

[0128] That is, the air conditioning system (100) can have different driving modes depending on the driving conditions.

[0129] For example, when the driving condition corresponds to the first condition, the vehicle may be driven in the first mode, when the driving condition corresponds to the second condition, the vehicle may be driven in the second mode, when the driving condition corresponds to the third condition, the vehicle may be driven in the third mode, and when the driving condition corresponds to the fourth condition, the vehicle may be driven in the fourth mode.

[0130] In this case, each of the first mode to the fourth mode can be set differently.

[0131] The above driving status may be the cooling operation, the heating operation, or the defrosting operation, and the temperature status may be the outside temperature.

[0132] During the cooling operation or the defrosting operation, the outdoor heat exchanger (31) performs heat exchange of the refrigerant delivered from at least one of the plurality of turbo compressors (11, 12), the outdoor expansion valve (32) performs expansion of the refrigerant delivered from the outdoor heat exchanger (31), the plurality of internal heat exchangers (41, 42, 43) performs heat exchange of the refrigerant delivered from the outdoor expansion valve (32), the indoor expansion valve (50) performs expansion of the refrigerant delivered from the plurality of internal heat exchangers (41, 42, 43), the indoor phase separator (61) separates the phase of the refrigerant delivered from the indoor expansion valve (50), and delivers the separated gaseous refrigerant to the plurality of turbo compressors (11, 12) and the liquid refrigerant to the shell-and-tube heat exchanger (71), and the shell-and-tube heat exchanger (71) Heat exchange of the liquid refrigerant transferred from the phase separator (61) is performed, and the heat-exchanged refrigerant can be transferred to the plurality of turbo compressors (11, 12).

[0133] That is, during the cooling operation or the defrosting operation, the refrigerant can be transferred from at least one of the plurality of turbo compressors (11, 12) to the outdoor heat exchanger (31), from the outdoor heat exchanger (31) to the outdoor expansion valve (32), from the outdoor expansion valve (32) to the plurality of internal heat exchangers (41, 42, 43), from the plurality of internal heat exchangers (41, 42, 43) to the indoor expansion valve (50), from the indoor expansion valve (50) to the indoor phase separator (61), from the indoor phase separator (61) to the shell-and-tube heat exchanger (71) and at least one of the plurality of turbo compressors (11, 12), and from the shell-and-tube heat exchanger (71) to at least one of the plurality of turbo compressors (11, 12).

[0134] Accordingly, the air conditioning system (100) can cause the refrigerant to circulate from the plurality of turbo compressors (11, 12) toward the outdoor heat exchanger (31) during the cooling operation or the defrosting operation.

[0135] During the heating operation, the outdoor heat exchanger (31) performs heat exchange of the refrigerant to be delivered to one or more of the plurality of turbocompressors (11, 12), the outdoor expansion valve (32) performs expansion of the refrigerant to be delivered to the outdoor heat exchanger (31), the plurality of internal heat exchangers (41, 42, 43) performs heat exchange of the refrigerant to be delivered to the outdoor expansion valve (32), the indoor expansion valve (50) performs expansion of the refrigerant to be delivered to the plurality of internal heat exchangers (41, 42, 43), the indoor phase separator (61) separates the phase of the refrigerant to be delivered to the indoor expansion valve (50) and delivers it, and the shell-and-tube heat exchanger (71) can perform heat exchange of the refrigerant to be delivered to the phase separator (61).

[0136] That is, during the heating operation, the refrigerant can be transferred from at least one of the plurality of turbocompressors (11, 12) to the shell-and-tube heat exchanger (71), from the shell-and-tube heat exchanger (71) to the phase separator (61), from the phase separator (61) to the indoor expansion valve (50), from the indoor expansion valve (50) to the plurality of internal heat exchangers (41, 42, 43), from the plurality of internal heat exchangers (41, 42, 43) to the outdoor expansion valve (32), from the outdoor expansion valve (32) to the outdoor heat exchanger (31), and from the outdoor heat exchanger (31) to at least one of the plurality of turbocompressors (11, 12).

[0137] Accordingly, the air conditioning system (100) can cause the refrigerant to circulate from the plurality of turbo compressors (11, 12) toward the shell-and-tube heat exchanger (71) during the heating operation.

[0138] The above plurality of turbo compressors (11, 12) are included in the compression unit (10) and can compress refrigerant.

[0139] Each of the above plurality of turbo compressors (11, 12) can compress the refrigerant twice and discharge it.

[0140] The above plurality of turbo compressors (11, 12) may have different capacities.

[0141] The capacity of one of the above plurality of turbo compressors (11, 12) may be 50 [%] or less of the capacity of the other.

[0142] For example, if there are two of the above-described multiple turbo compressors (11, 12), one may have a capacity of X and the other may have a capacity of 0.5X.

[0143] Accordingly, the refrigerant can be compressed differently in each of the plurality of turbo compressors (11, 12).

[0144] The above plurality of turbo compressors (11, 12) can be driven one or more times to compress the refrigerant depending on the operating conditions.

[0145] The above plurality of turbo compressors (11, 12) can be connected in series or parallel by switching the flow path according to the switching of the first four-way valve (21).

[0146] Here, the serial operation of the plurality of turbo compressors (11, 12) may be a case where the refrigerant is compressed twice in the first and second stages of one compressor (11), and then compressed twice in the first and second stages of the other compressor (12), thereby compressing the refrigerant in four stages, and the parallel operation of the plurality of turbo compressors (11, 12) may be a case where the refrigerant is branched and introduced into the inlet of each of the plurality of turbo compressors (11, 12), and then the refrigerant is compressed twice in the first and second stages of one compressor (11) and discharged, and then the discharged refrigerants are combined, thereby compressing the refrigerant twice in two stages.

[0147] The above-described plurality of turbo compressors (11, 12) can also be driven in cooling operation / heating operation / defrosting operation by switching the flow path according to the switching of the second four-way valve (22).

[0148] Meanwhile, the compression unit (10) may further include an injection solenoid valve (111, 121) that closes the piping between the first and second stages of each of the plurality of turbo compressors (11, 12) and the internal heat exchange unit (40), and a check valve (112, 122) that prevents reverse flow of the refrigerant flowing through the injection solenoid valve (111, 121) to the passage between the first and second stages of each of the plurality of turbo compressors (11, 12).

[0149] The above injection solenoid valve (111, 121) may be a valve that opens and closes a pipe through which refrigerant is transferred from the internal heat exchanger (40) to a passage between the first and second stages of each of the plurality of turbo compressors (11, 12).

[0150] The above injection solenoid valve (111, 121) is normally open and can be opened when refrigerant is transferred between the first and second stages of each of the plurality of turbo compressors (11, 12).

[0151] The compression unit (10) may also further include a check valve (113, 123) that prevents backflow of refrigerant flowing from each of the plurality of turbo compressors (11, 12) to the outdoor heat exchange unit (30).

[0152] The compression unit (10) may also further include an internal flow path solenoid valve (114, 124) for controlling the internal flow path of each of the plurality of turbo compressors (11, 12) and a check valve (115, 125) for preventing reverse flow of refrigerant in the internal flow path.

[0153] The above internal flow path solenoid valve (114, 124) may be a valve that blocks the flow path so that at least a portion of the refrigerant discharged from the first stage of each of the plurality of turbo compressors (11, 12) flows into the internal flow path of each of the plurality of turbo compressors (11, 12).

[0154] The above internal euro solenoid valve (114, 124) is normally closed and can be opened when supplying refrigerant to the internal euro.

[0155] For example, in a case where it is necessary to rapidly cool the internal motor of each of the plurality of turbo compressors (11, 12) or to rapidly supply refrigerant to the gas bearing, the internal flow path solenoid valve (114, 124) may be opened to allow at least a portion of the refrigerant flowing into the second stage of each of the plurality of turbo compressors (11, 12) to flow into the internal flow path.

[0156] Accordingly, when the motors of the plurality of turbo compressors (11, 12) overheat or the gas bearings are short of refrigerant, refrigerant can be supplied to the internal passages to cool the motors of the plurality of turbo compressors (11, 12) or to resolve the refrigerant shortage in the gas bearings.

[0157] The above first four-way valve (21) is included in the valve section (20) and can switch the flow path of the refrigerant flowing into or discharged from the plurality of turbo compressors (11, 12) depending on whether the plurality of turbo compressors (11, 12) are driven in series or in parallel.

[0158] The first four-way valve (21) includes a first valve stage (E) connected to the inlet of a first stage of one of the plurality of turbo compressors (11, 12), a second valve stage (S) connected to the inlet of each of the plurality of turbo compressors (11, 12), a third valve stage (D) connected to the discharge of a second stage of the one compressor (11), and a fourth valve stage (C) connected to the inlet of the outdoor heat exchanger (31), and can open and close each of the first to fourth valve stages (E, S, D, C) or connect any two or more of them.

[0159] For example, by connecting the first valve stage (E) and the third valve stage (D), the second valve stage (S) and the fourth valve stage (C), or by opening / closing at least one of the first valve stage to the fourth valve stage (E, S, D, C), the path through which the refrigerant is introduced into the plurality of turbo compressors (11, 12) and / or the path through which the refrigerant is discharged from the plurality of turbo compressors (11, 12) can be switched.

[0160] Accordingly, the plurality of turbo compressors (11, 12) can be operated in series or parallel.

[0161] The second four-way valve (22) is included in the valve section (20) and can switch the flow path of the refrigerant flowing into or discharged from the plurality of turbo compressors (11, 12) depending on whether the cooling operation, the heating operation, or the defrosting operation is in progress.

[0162] The second four-way valve (22) includes a first valve stage (D) connected to the discharge ports of two stages of each of the plurality of turbo compressors (11, 12), a second valve stage (E) connected to the discharge port of the shell-and-tube heat exchanger (71), a third valve stage (S) connected to the inlet port of the accumulator (13) of the plurality of turbo compressors (11, 12), and a fourth valve stage (C) connected to the inlet port of the outdoor heat exchanger (31), and can open and close each of the first valve stage to the fourth valve stage (D, E, S, C) or connect any two or more of them.

[0163] For example, by connecting the first valve stage (D) and the second valve stage (E), the third valve stage (S) and the fourth valve stage (C), or by opening / closing at least one of the first valve stage to the fourth valve stage (D, E, S, C), the path through which the refrigerant is introduced into the plurality of turbo compressors (11, 12) and / or the path through which the refrigerant is discharged from the plurality of turbo compressors (11, 12) can be switched.

[0164] Accordingly, the plurality of turbo compressors (11, 12) can be operated in cooling / defrosting operation or heating operation.

[0165] The above outdoor heat exchanger (31) is arranged between the plurality of turbo compressors (11, 12) and the outdoor expansion valve (32), so that heat exchange can be performed on the refrigerant delivered from one or more of the plurality of turbo compressors (11, 12) or the refrigerant to be delivered to one or more of the plurality of turbo compressors (11, 12).

[0166] The above outdoor heat exchanger (31) can transfer refrigerant to the outdoor expansion valve (32) during the cooling operation or the defrosting operation, and can receive refrigerant from the outdoor expansion valve (32) during the heating operation.

[0167] The above outdoor expansion valve (32) is arranged between the outdoor phase separator (33) and the plurality of indoor heat exchangers (41, 42, 43), so that expansion of the refrigerant delivered from the outdoor phase separator (33) or the refrigerant delivered from the plurality of indoor heat exchangers (41, 42, 43) can be achieved.

[0168] The above outdoor expansion valve (32) can transfer refrigerant to the plurality of indoor heat exchangers (41, 42, 43) during the cooling operation or the defrosting operation, and can receive refrigerant from the plurality of indoor heat exchangers (41, 42, 43) during the heating operation.

[0169] The above outdoor expansion valve (32) may include a check valve (321) that prevents backflow of the refrigerant.

[0170] The above check valve (321) may be a valve that prevents reverse flow of the refrigerant by restricting the refrigerant to flow in only one direction.

[0171] Meanwhile, the air conditioning system (100) may further include an outdoor phase separator (33) which is arranged between the outdoor heat exchanger (31) and the outdoor expansion valve (32) to separate the phase of the refrigerant delivered from the outdoor expansion valve (32) during the heating operation and deliver the separated refrigerant in the gas phase to the plurality of turbo compressors (11, 12).

[0172] The above outdoor phase separator (33) can transfer the refrigerant received from the outdoor heat exchanger (31) to the outdoor expansion valve (32) during the cooling operation or the defrosting operation.

[0173] The above outdoor phase separator (33) can separate the phase of the refrigerant delivered from the outdoor expansion valve (32) during the heating operation, deliver the separated gaseous refrigerant to the plurality of turbo compressors (11, 12) through the bypass pipe (331), and deliver the separated liquid refrigerant to the outdoor heat exchanger (31).

[0174] Here, the bypass pipe (331) may include a valve (331) that closes the pipe connecting the outdoor phase separator (33) and the plurality of turbo compressors (11, 12).

[0175] When the valve (331) is closed, the refrigerant is delivered to the outdoor heat exchanger (31), and when the valve (331) is open, the refrigerant can be delivered to the plurality of turbo compressors (11, 12).

[0176] The above valve (331) can be closed (CLOSE) during the cooling operation or the defrosting operation, and opened (OPEN) during the heating operation.

[0177] The above-mentioned plurality of indoor heat exchangers (41, 42, 43) are included in the internal heat exchange unit (40), and heat exchange of the refrigerant transferred from the external heat exchange unit (30) or the indoor expansion valve (50) can be performed.

[0178] The above-mentioned plurality of indoor heat exchangers (41, 42, 43) may preferably be composed of three or more.

[0179] The above multiple indoor heat exchangers (41, 42, 43) can be arranged in series.

[0180] Accordingly, the refrigerant transferred from one or more of the outdoor heat exchangers (31, 32, 33) may be sequentially introduced into each of the plurality of indoor heat exchangers (41, 42, 43) and then heat exchange may be performed.

[0181] A pipe may be provided between one or more of the plurality of indoor heat exchangers (41, 42, 43) and one or more of the plurality of turbo compressors (11, 12).

[0182] Accordingly, one or more of the plurality of indoor heat exchangers (41, 42, 43) and one or more of the plurality of turbo compressors (11, 12) are connected by a pipe, so that refrigerant can be transferred from one or more of the plurality of indoor heat exchangers (41, 42, 43) to one or more of the plurality of turbo compressors (11, 12).

[0183] The above plurality of indoor heat exchangers (41, 42, 43) are preferably each connected to the plurality of turbo compressors (11, 12) by pipes so as to deliver refrigerant to each of the plurality of turbo compressors (11, 12).

[0184] One or more of the plurality of indoor heat exchangers (41, 42, 43) can transfer at least a portion of the heat-exchanged refrigerant to one or more of the plurality of turbocompressors (11, 12).

[0185] The above-described plurality of indoor heat exchangers (41, 42, 43) may include a first indoor heat exchanger (41), a second indoor heat exchanger (42), and a third indoor heat exchanger (43) arranged in series.

[0186] The above plurality of indoor heat exchangers (41, 42, 43) can be arranged in the order of the first indoor heat exchanger to the third indoor heat exchanger (41, 42, 43).

[0187] Accordingly, the refrigerant received from the outdoor expansion valve (32) may be introduced in the order of the first indoor heat exchanger to the third indoor heat exchanger (41, 42, 43) and heat exchange may be performed.

[0188] The above first indoor heat exchanger (41) may be an internal heat exchanger for a gas bearing.

[0189] The first indoor heat exchanger (41) can also deliver refrigerant to the plurality of turbo compressors (11, 12) so that at least a portion of the heat-exchanged refrigerant circulates through the internal passages of each of the plurality of turbo compressors (11, 12) to cool the motors of the plurality of turbo compressors (11, 12).

[0190] The first indoor heat exchanger (41) can also deliver refrigerant to the plurality of turbo compressors (11, 12) so that at least a portion of the heat-exchanged refrigerant circulates through the internal passages of each of the plurality of turbo compressors (11, 12) to supply a portion of the refrigerant to the gas bearings of the plurality of turbo compressors (11, 12).

[0191] The above second indoor heat exchanger (42) may be an internal heat exchanger for injection.

[0192] The second indoor heat exchanger (42) can deliver refrigerant to one or more of the plurality of turbo compressors (11, 12) so that at least a portion of the heat-exchanged refrigerant is introduced into the first stage inlet of one or more of the plurality of turbo compressors (11, 12) and compressed.

[0193] The above third indoor heat exchanger (43) may be an internal heat exchanger for supercooling.

[0194] The third indoor heat exchanger (43) can deliver refrigerant to one or more of the plurality of turbo compressors (11, 12) so that at least a portion of the heat-exchanged refrigerant is introduced into the second-stage inlet of one or more of the plurality of turbo compressors (11, 12) and compressed.

[0195] Each of the first to third indoor heat exchangers (41, 42, 43) includes an inlet valve (411, 421, 431) that opens and closes an inlet portion, so that refrigerant received from a previous heat exchanger can undergo heat exchange in one or more indoor heat exchangers according to the operation of the inlet valve.

[0196] For example, when the first inlet valve (411) provided in the first indoor heat exchanger (41) is operated in the open state, the refrigerant flows into the first indoor heat exchanger (41), and heat exchange of the refrigerant occurs in the first indoor heat exchanger (41). When the second inlet valve (421) provided in the second indoor heat exchanger (42) is operated in the close state, the refrigerant does not flow into the second indoor heat exchanger (42), and heat exchange of the refrigerant does not occur in the second indoor heat exchanger (42).

[0197] In the internal heat exchanger (40) as described above, the first indoor heat exchanger (41) can perform heat exchange of the refrigerant in all of the cooling operation, heating operation, and defrosting operation through the inlet valve.

[0198] That is, the first indoor heat exchanger (41) can perform heat exchange during each of the cooling operation, the heating operation, and the defrosting operation.

[0199] Accordingly, the inlet valve (411) of the first indoor heat exchanger (41) can be opened during all of the cooling operation, the heating operation, and the defrosting operation.

[0200] Meanwhile, the internal heat exchanger (40) may further include a cooler (80) that cools the refrigerant vaporized in the first indoor heat exchanger (41) and delivers it to the first stage inlet of each of the plurality of turbo compressors (11, 12).

[0201] That is, when heat exchange is performed in the first indoor heat exchanger (41), the cooler (80) can cool the refrigerant that has been vaporized in the first indoor heat exchanger (41) and transfer it to the first stage inlet of each of the plurality of turbo compressors (11, 12).

[0202] Here, the flow path through which the refrigerant is delivered from the cooler (80) to the first stage inlet of each of the plurality of turbo compressors (11, 12) may include an internal flow path of each of the plurality of turbo compressors (11, 12).

[0203] Accordingly, the refrigerant delivered from the cooler (80) to the first stage inlet of each of the plurality of turbo compressors (11, 12) may circulate through the internal passages of each of the plurality of turbo compressors (11, 12) to cool the motors of each of the plurality of turbo compressors (11, 12) and supply some of the refrigerant to the gas bearings of the plurality of turbo compressors (11, 12).

[0204] The above indoor expansion valve (50) is included in the internal expansion unit (50), and expansion of the refrigerant transmitted from the internal heat exchange unit (40) or the internal phase separation unit (60) can be achieved.

[0205] The above indoor phase separator (61) is arranged between the indoor expansion valve (50) and the shell-and-tube heat exchanger (71), and can separate the phase of the refrigerant delivered from the expansion valve (50) into a gas phase and a liquid phase during the cooling operation or the defrosting operation, deliver the separated gas phase refrigerant to the plurality of turbo compressors (11, 12), and deliver the separated liquid phase refrigerant to the shell-and-tube heat exchanger (71).

[0206] That is, the gaseous refrigerant separated in the indoor phase separator (61) is bypassed to the plurality of turbo compressors (11, 12), and the liquid refrigerant is transferred to the shell-and-tube heat exchanger (71) to be subjected to heat exchange.

[0207] In this case, the indoor phase separator (61) may include a bypass valve (611) that blocks the flow path for bypassing the gaseous refrigerant to the pipe connected to the inlet of the plurality of turbocompressors (11, 12).

[0208] The above shell-and-tube heat exchanger (71) is arranged between the indoor phase separator (61) and the plurality of turbo compressors (11, 12), so that heat exchange of refrigerant transferred from the indoor phase separator (61) or one or more of the plurality of turbo compressors (11, 12) can be performed.

[0209] The above air conditioning system (100) may also further include a bypass solenoid valve (91) that bypasses a portion of the refrigerant to the outdoor heat exchanger (30) before it is introduced into the plurality of turbo compressors (11, 12).

[0210] The above bypass solenoid valve (91) is normally closed, and can be opened when a portion of the refrigerant is transferred to the outdoor heat exchanger (30) before being introduced into the plurality of turbo compressors (11, 12).

[0211] For example, when the temperature of the refrigerant flowing into the outdoor heat exchange unit (30) is lower than a certain standard, the bypass solenoid valve (91) is opened so that a portion of the refrigerant before flowing into the plurality of turbo compressors (11, 12) is compressed in the plurality of turbo compressors (11, 12) and combined with the refrigerant flowing into the outdoor heat exchange unit (30), thereby controlling the temperature of the refrigerant flowing into the outdoor heat exchange unit (30).

[0212] The above air conditioning system (100) may also further include a check valve (92) that prevents reverse flow of refrigerant discharged from the first compressor (11) and delivered to the second compressor (12).

[0213] Accordingly, when the plurality of turbo compressors (11, 12) are driven in series, the reverse flow of the refrigerant transferred from the first compressor (11) to the inlet of the second compressor (12) can be prevented.

[0214] The air conditioning system (100) including the plurality of turbo compressors (11, 12), the four-way valve (20), the outdoor heat exchanger (31), the outdoor expansion valve (32), the outdoor phase separator (33), the plurality of internal heat exchangers (41, 42, 43), the indoor expansion valve (50), the indoor phase separator (61) and the shell-and-tube heat exchanger (71) can be operated to circulate refrigerant as shown in FIG. 7, FIG. 9, FIG. 11 or FIG. 13 depending on the operating conditions.

[0215] The above driving conditions can be divided into multiple conditions depending on whether the cooling / heating / defrosting operation is performed and the temperature status.

[0216] The above driving conditions may include, for example, a first condition in which the driving corresponds to the cooling operation and the temperature state is 27 [℃] or higher, a second condition in which the driving corresponds to the cooling operation and the temperature state is less than 27 [℃], a third condition in which the driving corresponds to the heating operation, and a fourth condition in which the driving corresponds to the defrosting operation.

[0217] That is, the above driving conditions may include the first condition to the fourth condition, and the air conditioning system (100) may be operated in a driving mode corresponding to each of the above driving conditions.

[0218] Below, the specific operation and the resulting results / effects for each operating condition of the air conditioning system (100) are described.

[0219] <Condition 1>

[0220] When the above driving conditions correspond to the first condition, the driving results may be as shown in Fig. 7, and the PH diagram comparing the driving results with the existing driving results may be as shown in Fig. 8.

[0221] The above air conditioning system (100) can be operated as shown in FIG. 7 to circulate the refrigerant when the operation corresponds to the cooling operation and the temperature state is 27 [℃] or higher.

[0222] The above first four-way valve (21) can switch the flow path so that the second stage discharge port of one compressor (11) among the plurality of turbo compressors (11, 12) and the first stage inlet port of the other compressor (12) are connected, and the inlet port of the outdoor heat exchanger (31) and the discharge port of the shell-and-tube heat exchanger (71) are connected.

[0223] Accordingly, the plurality of turbo compressors (11, 12) can be driven in series to compress the refrigerant.

[0224] The second four-way valve (22) can switch the flow path so that the discharge port of the shell-and-tube heat exchanger (71) and the inlet port of the accumulator (13) of the plurality of turbo compressors (11, 12) are connected, and the discharge port of the second stage of the other compressor (12) and the inlet port of the outdoor heat exchanger (31) are connected.

[0225] Accordingly, the plurality of turbo compressors (11, 12) can compress the refrigerant so that the refrigerant circulates according to the cooling operation.

[0226] The above plurality of turbo compressors (11, 12) can compress the refrigerant in the order of the first and second stages of the first compressor (11), the first and second stages of the other compressor (12), and deliver the refrigerant compressed in four stages from the second stage discharge port of the other compressor (12) to the outdoor heat exchanger (31).

[0227] The above-mentioned plurality of indoor heat exchangers (41, 42, 43) can each have their respective inlet valves (411, 421, 431) opened, so that heat exchange can take place in each.

[0228] In this case, one (42) positioned in the middle can transfer the vaporized refrigerant to the first stage inlet of the other compressor (12), and one (43) positioned before the indoor expansion valve (50) can transfer the vaporized refrigerant to the second stage inlet of the first compressor (11).

[0229] That is, the second indoor heat exchanger (42) can inject the refrigerant that has been heat-exchanged and turned into vapor into the second compressor (12), and the third indoor heat exchanger (43) can inject the refrigerant that has been heat-exchanged and turned into vapor into the second stage inlet of the first compressor (11).

[0230] At this time, the solenoid valve (111) of the first compressor (11) can be operated in an open state so that the refrigerant is transferred from the third indoor heat exchanger (43) to the second stage inlet of the first compressor (11), and the solenoid valve (121) of the second compressor (12) can be operated in a closed state so that the refrigerant is not transferred from the third indoor heat exchanger (43) to the second stage inlet of the second compressor (12).

[0231] In addition, the first indoor heat exchanger (41) cools the vaporized refrigerant by transferring it to the cooler (80), and the refrigerant cooled in the cooler (80) is transferred to the first stage inlet through the internal passages of each of the plurality of turbo compressors (11, 12), thereby cooling the motors of each of the plurality of turbo compressors (11, 12) and supplying some of the refrigerant to the gas bearing.

[0232] The specific operation of the air conditioning system (100) in this case and the results thereof are described below with reference to FIG. 8.

[0233] Low-temperature and low-pressure gaseous refrigerant is introduced into the first stage inlet of the first compressor (11), and after the first compression, the gaseous refrigerant with the first temperature and pressure increase is discharged and then moves through the communication pipe, and after combining with the medium-pressure gaseous refrigerant (first injection) delivered from the third indoor heat exchanger (43) (internal heat exchanger for supercooling), the temperature is lowered and then introduced into the second stage inlet, and the gaseous refrigerant with the temperature and pressure increase is discharged through the second compression process.

[0234] The refrigerant discharged through the first four-way valve (21) (On) is combined with the medium-pressure gaseous refrigerant (secondary injection) delivered from the second indoor heat exchanger (42) (internal heat exchanger for injection) and then, after a temperature drop, is introduced into the first stage inlet of the second compressor (12).

[0235] The gaseous refrigerant that has been heated and pressurized after the third compression in the first stage of the second compressor (12) is introduced into the second stage inlet through the communication pipe, and the high-temperature gaseous refrigerant that has been heated and pressurized after the final fourth compression is discharged.

[0236] In this way, by driving the plurality of turbo compressors (11, 12) in series to compress the refrigerant, the compression efficiency is improved compared to the existing two-stage split compression of the refrigerant, and by reducing the compression ratio of each compressor to avoid the surge region, the reliability of the compressor can be improved and stable continuous cooling operation can be induced.

[0237] That is, compression efficiency is improved by distributing the pressure ratio, efficiency is improved by reducing the compressor rotation speed according to the increase in cooling capacity by avoiding the surge region, and the rotation speed restriction according to the discharge temperature is minimized by reducing the compressor discharge temperature, so that it is possible to induce cooling capacity maintenance in case of overload in cooling.

[0238] All high-temperature, high-pressure gaseous refrigerants are radiated to the outdoor air side in the outdoor heat exchanger (31), then converted into medium-temperature, high-pressure liquid refrigerants and discharged to the outdoor phase separator (33) and the outdoor expansion valve (32).

[0239] At this time, the bypass solenoid valve (331) of the outdoor separator (33) can be closed to prevent the flow of refrigerant.

[0240] A portion of the medium-temperature, high-pressure liquid refrigerant expands to the intermediate pressure of the first stage inlet of the second compressor (12) in the first indoor heat exchanger (41) (internal heat exchanger for gas bearing) after branching, and then heat exchanges with the medium-temperature, high-pressure liquid refrigerant (primary subcooling of the liquid refrigerant) and then vaporizes, and then cools the motors of each of the plurality of turbo compressors (11, 12) through inverter refrigerant cooling in the cooler (80), and supplies a portion of the refrigerant to the gas bearing side of the mechanism, and then combines with the refrigerant on the first stage inlet side of each.

[0241] In this way, by supplying the refrigerant for the gas bearing at a low or medium pressure on the first stage inlet side of each compressor (11, 12) in a high-pressure state at the condensation outlet, stable refrigerant supply is possible without problems such as backflow, and the inflow of incompressible liquid refrigerant due to the refrigerant vaporized in the internal heat exchanger for the gas bearing is prevented, thereby enabling stable management of the required pressure of the gas bearing. In addition, by controlling the bypass refrigerant flow rate based on the superheat degree at the outlet of the internal heat exchanger, it is possible to minimize performance degradation due to excessive refrigerant bypass (ⓛ in FIG. 8).

[0242] Some of the first-stage supercooled medium-temperature, high-pressure liquid refrigerant expands to the intermediate pressure at the inlet side of the first stage of the second compressor (12) in the second indoor heat exchanger (42) (internal heat exchanger for injection) after branching, and then heat-exchanges with the medium-temperature, high-pressure liquid refrigerant (secondary supercooling of the liquid refrigerant) and becomes vaporized, and is combined with the medium-temperature, medium-pressure gaseous refrigerant discharged from the second-stage discharge side of the first compressor (11) and flows into the first-stage inlet side of the second compressor (12).

[0243] Some of the secondary supercooled medium-temperature, high-pressure liquid refrigerant is expanded to the intermediate pressure at the discharge side of the first stage of the first compressor (11) in the third indoor heat exchanger (43 (internal heat exchanger for supercooling) after branching, and then heat-exchanged with the medium-temperature, high-pressure liquid refrigerant (tertiary supercooling of the liquid refrigerant) and then vaporized, and is combined with the medium-temperature, medium-pressure gaseous refrigerant discharged from the discharge side of the first stage of the first compressor (11) and introduced into the second stage inlet of the first compressor (11).

[0244] In this way, by inducing a decrease in evaporator inlet enthalpy through two additional subcoolings for the medium-temperature liquid refrigerant based on the same cooling capacity through 1 / 2 injection, the compressor rotation speed is reduced by the amount of the increase in evaporator △h, thereby enabling high-efficiency operation through a decrease in compressor input energy (② of Fig. 8).

[0245] In addition, under cooling overload conditions, the evaporator inlet enthalpy is reduced through two additional subcoolings for the medium-temperature liquid refrigerant based on the same compressor rotation speed, thereby enabling high cooling through an increase in cooling capacity equivalent to the increase in evaporator △h.

[0246] In addition, by minimizing compressor rotation speed restrictions through reducing compressor discharge temperature, it becomes possible to maintain cooling power under cooling overload conditions.

[0247] The medium-temperature, high-pressure liquid refrigerant that is finally subcooled in the third indoor heat exchanger (43) is expanded to low pressure in the indoor expansion valve (50) and then converted into a two-phase refrigerant, and then introduced into the indoor phase separator (61).

[0248] Inside the indoor phase separator (61), the liquid refrigerant among the two-phase refrigerants is accumulated toward the bottom of the indoor phase separator (61) by gravity, and the gaseous refrigerant is separated toward the top. The gaseous refrigerant separated toward the top bypasses the shell-and-tube heat exchanger (71) (shell-tube evaporator) and is combined toward the discharge side. The liquid refrigerant accumulated at the bottom of the indoor phase separator (61) absorbs heat from cold water in the shell-and-tube heat exchanger (71) and then turns into gas and is discharged.

[0249] By inducing the dryness of the refrigerant flowing into the shell-and-tube heat exchanger (71) corresponding to the evaporator while passing through the phase separator (61) before the low-temperature, low-pressure two-phase refrigerant after expansion in the indoor expansion valve (50) above to be as close as possible to the saturated liquid line before flowing into the evaporator, the cooling capacity is improved by increasing the evaporator △h through inducing an additional decrease in the enthalpy at the evaporator inlet, and by bypassing the gaseous refrigerant as much as the dryness before flowing into the evaporator to the evaporator outlet, the refrigerant pressure loss due to the flowing gas within the evaporator is minimized, thereby improving the cooling capacity (③ of FIG. 8).

[0250] After this, all low-temperature, low-pressure gaseous refrigerant that has passed through the indoor phase separator (61) and the shell-and-tube heat exchanger (71) is introduced into the accumulator (13), and after being phase separated / converted in the accumulator (13), is introduced into the first stage inlet of the first compressor (11).

[0251] <Condition 2>

[0252] When the above driving conditions correspond to the second condition, the driving results may be as shown in Fig. 9, and the PH diagram comparing the driving results with the existing driving results may be as shown in Fig. 10.

[0253] The above air conditioning system (100) can be operated as shown in Fig. 9 to circulate the refrigerant when the operation corresponds to cooling operation and the temperature state is less than 27 [℃].

[0254] The above first four-way valve (21) can switch the flow path so that the second stage discharge port of one compressor (11) among the plurality of turbo compressors (11, 12) and the inlet port of the outdoor heat exchanger (31) are connected, and the first stage inlet port of one compressor (11) and the first stage inlet port of the other compressor (12) are connected.

[0255] Accordingly, the plurality of turbo compressors (11, 12) can be driven in parallel to compress the refrigerant.

[0256] The second four-way valve (22) can switch the flow path so that the discharge port of the shell-and-tube heat exchanger (71) and the inlet port of the accumulator (13) of the plurality of turbo compressors (11, 12) are connected, and the discharge port of the second stage of the other compressor (12) and the inlet port of the outdoor heat exchanger (31) are connected.

[0257] Accordingly, the plurality of turbo compressors (11, 12) can compress the refrigerant so that the refrigerant circulates according to the cooling operation.

[0258] The above plurality of turbo compressors (11, 12) can compress refrigerant in the first and second stages, respectively, with the first compressor (11) and the other compressor (12), and deliver the refrigerant compressed in two stages from the second-stage discharge portion of the first compressor (11) and the second-stage discharge portion of the other compressor (12) to the outdoor heat exchanger (31).

[0259] The above-described plurality of indoor heat exchangers (41, 42, 43) can be configured so that heat exchange can take place in each of the two heat exchangers (41, 43) by opening the inlet valves (411, 431) of each of the two heat exchangers (41, 43) arranged at both ends.

[0260] In this case, one of the two heat exchangers (41, 43) positioned before the expansion valve (50) can transfer the vaporized refrigerant to the second stage inlet of the first compressor (11) and the second stage inlet of the other compressor (12), respectively.

[0261] That is, the third indoor heat exchanger (43) can inject the refrigerant that has been heat-exchanged and vaporized into the second stage inlet of each of the first compressor (11) and the second compressor (12).

[0262] At this time, the solenoid valves (111, 121) of the first compressor (11) and the second compressor (12) can be operated open to allow refrigerant to be transferred from the third indoor heat exchanger (43) to the second stage inlet of each of the first compressor (11) and the second compressor (12).

[0263] In addition, the first indoor heat exchanger (41) cools the vaporized refrigerant by transferring it to the cooler (80), and the refrigerant cooled in the cooler (80) is transferred to the first stage inlet through the internal passages of each of the plurality of turbo compressors (11, 12), thereby cooling the motors of each of the plurality of turbo compressors (11, 12) and supplying some of the refrigerant to the gas bearing.

[0264] Meanwhile, in such a case, the inlet valve (421) of the second indoor heat exchanger (42) may be driven to close.

[0265] The specific operation of the air conditioning system (100) in this case and the resulting results are described below with reference to FIG. 10.

[0266] Low-temperature, low-pressure gaseous refrigerant is divided and introduced into each of the first stage of the first compressor (11) and the first stage of the second compressor (12), and after the first compression, the first heated and pressurized gaseous refrigerant is discharged, and then, when moving through the communication pipe, it is combined with the medium-pressure gaseous refrigerant (first injection) delivered from the third indoor heat exchanger (43), and after a temperature drop, it is introduced into the second-stage inlet, and through the second compression process, the final pressurized high-temperature, high-pressure gaseous refrigerant is discharged.

[0267] In this way, by operating the above-mentioned multiple turbo compressors (11, 12) in parallel, the compressor efficiency can be improved due to the improved compression efficiency when the load is distributed compared to the existing single compressor.

[0268] All high-temperature, high-pressure gaseous refrigerants are radiated to the outdoor air side in the outdoor heat exchanger (31), then converted into medium-temperature, high-pressure liquid refrigerants and discharged to the outdoor phase separator (33) and the outdoor expansion valve (32).

[0269] At this time, the bypass solenoid valve (331) of the outdoor separator (33) can be closed to prevent the flow of refrigerant.

[0270] A portion of the medium-temperature, high-pressure liquid refrigerant expands to the intermediate pressure of the first stage inlet of the second compressor (12) in the first indoor heat exchanger (41) (internal heat exchanger for gas bearing) after branching, and then heat exchanges with the medium-temperature, high-pressure liquid refrigerant (primary subcooling of the liquid refrigerant) and then vaporizes, and then cools the motors of each of the plurality of turbo compressors (11, 12) through inverter refrigerant cooling in the cooler (80), and supplies a portion of the refrigerant to the gas bearing side of the mechanism, and then combines with the refrigerant on the first stage inlet side of each.

[0271] In this way, by supplying the refrigerant for the gas bearing at a low or medium pressure on the first stage inlet side of each compressor (11, 12) in a high-pressure state at the condensation outlet, stable refrigerant supply is possible without problems such as backflow, and the inflow of incompressible liquid refrigerant due to the refrigerant vaporized in the internal heat exchanger for the gas bearing is prevented, thereby enabling stable management of the required pressure of the gas bearing. In addition, by controlling the bypass refrigerant flow rate based on the superheat degree at the outlet of the internal heat exchanger, it is possible to minimize performance degradation due to excessive refrigerant bypass (ⓛ in FIG. 10).

[0272] Some of the secondary supercooled medium-temperature, high-pressure liquid refrigerant is expanded to an intermediate pressure at the discharge side of the first stage of each of the first compressor (11) and the second compressor (12) in the third indoor heat exchanger (43 (internal heat exchanger for supercooling) after branching, and then heat-exchanges with the medium-temperature, high-pressure liquid refrigerant (tertiary supercooling of the liquid refrigerant) and becomes gaseous, and is combined with the medium-temperature, medium-pressure gaseous refrigerant discharged from the discharge side of the first stage of each of the first compressor (11) and the second compressor (12) and flows into the second-stage inlet of each of the first compressor (11) and the second compressor (12).

[0273] In this way, by inducing a decrease in evaporator inlet enthalpy through two additional subcoolings for the medium-temperature liquid refrigerant based on the same cooling capacity through 1 / 2 injection, the compressor rotation speed is reduced by the amount of the increase in evaporator △h, thereby enabling high-efficiency operation through a decrease in compressor input energy (② of Fig. 10).

[0274] The medium-temperature, high-pressure liquid refrigerant that is finally subcooled in the third indoor heat exchanger (43) is expanded to low pressure in the indoor expansion valve (50) and then converted into a two-phase refrigerant, and then introduced into the indoor phase separator (61).

[0275] Inside the indoor phase separator (61), the liquid refrigerant among the two-phase refrigerants is accumulated toward the bottom of the indoor phase separator (61) by gravity, and the gaseous refrigerant is separated toward the top. The gaseous refrigerant separated toward the top bypasses the shell-and-tube heat exchanger (71) (shell-tube evaporator) and is combined toward the discharge side. The liquid refrigerant accumulated at the bottom of the indoor phase separator (61) absorbs heat from cold water in the shell-and-tube heat exchanger (71) and then turns into gas and is discharged.

[0276] By inducing the dryness of the refrigerant flowing into the shell-and-tube heat exchanger (71) corresponding to the evaporator while passing through the indoor phase separator (61) before the low-temperature, low-pressure two-phase refrigerant that has been expanded in the indoor expansion valve (50) above to be as close as possible to the saturated liquid line before flowing into the evaporator, the cooling capacity is improved by increasing the evaporator △h through inducing an additional decrease in the enthalpy at the evaporator inlet, and by bypassing the gaseous refrigerant as much as the dryness before flowing into the evaporator to the evaporator outlet, the refrigerant pressure loss due to the flowing gas within the evaporator is minimized, thereby improving the cooling capacity (③ of FIG. 10).

[0277] After this, all low-temperature, low-pressure gaseous refrigerant that has passed through the indoor phase separator (61) and the shell-and-tube heat exchanger (71) is introduced into the accumulator (13), and after being phase separated / converted in the accumulator (13), is introduced into the first stage inlet of the first compressor (11).

[0278] <Condition 3>

[0279] When the above driving conditions correspond to the third condition, the driving results may be as shown in Fig. 11, and the PH diagram comparing the driving results with the existing driving results may be as shown in Fig. 12.

[0280] The above air conditioning system (100) can be operated as shown in FIG. 11 to circulate the refrigerant when the operation corresponds to the heating operation.

[0281] The above first four-way valve (21) can switch the flow path so that the second stage discharge port of one compressor (11) among the plurality of turbo compressors (11, 12) and the first stage inlet port of the other compressor (12) are connected, and the inlet port of the outdoor heat exchanger (31) and the discharge port of the shell-and-tube heat exchanger (71) are connected.

[0282] Accordingly, the plurality of turbo compressors (11, 12) can be driven in series to compress the refrigerant.

[0283] The second four-way valve (22) changes the flow path so that the inlet of the outdoor heat exchanger (31) and the inlet of the accumulator (13) of the plurality of turbo compressors (11, 12) are connected, and the discharge of the second stage of the other compressor (12) and the discharge of the shell-and-tube heat exchanger (71) are connected, so that the refrigerant can circulate in the opposite direction to the direction during the cooling operation.

[0284] Accordingly, the plurality of turbo compressors (11, 12) can compress the refrigerant so that the refrigerant circulates according to the heating operation.

[0285] The above plurality of turbo compressors (11, 12) can compress the refrigerant in the order of the first and second stages of the first compressor (11), the first and second stages of the other compressor (12), and deliver the refrigerant compressed in four stages from the second stage discharge port of the other compressor (12) to the shell-and-tube heat exchanger (71).

[0286] The above-mentioned plurality of indoor heat exchangers (41, 42, 43) can each have their respective inlet valves (411, 421, 431) opened, so that heat exchange can take place in each.

[0287] In this case, one (42) positioned in the middle can transfer the vaporized refrigerant to the first stage inlet of the other compressor (12), and one (43) positioned before the indoor expansion valve (50) can transfer the vaporized refrigerant to the second stage inlet of the first compressor (11).

[0288] That is, the second indoor heat exchanger (42) can inject the refrigerant that has been heat-exchanged and turned into vapor into the second compressor (12), and the third indoor heat exchanger (43) can inject the refrigerant that has been heat-exchanged and turned into vapor into the second stage inlet of the first compressor (11).

[0289] At this time, the solenoid valve (111) of the first compressor (11) can be operated in an open state so that the refrigerant is transferred from the third indoor heat exchanger (43) to the second stage inlet of the first compressor (11), and the solenoid valve (121) of the second compressor (12) can be operated in a closed state so that the refrigerant is not transferred from the third indoor heat exchanger (43) to the second stage inlet of the second compressor (12).

[0290] In addition, the first indoor heat exchanger (41) cools the vaporized refrigerant by transferring it to the cooler (80), and the refrigerant cooled in the cooler (80) is transferred to the first stage inlet through the internal passages of each of the plurality of turbo compressors (11, 12), thereby cooling the motors of each of the plurality of turbo compressors (11, 12) and supplying some of the refrigerant to the gas bearing.

[0291] The specific operation of the air conditioning system (100) in this case and the results thereof are described below with reference to FIG. 12.

[0292] Low-temperature and low-pressure gaseous refrigerant is introduced into the first stage inlet of the first compressor (11), and after the first compression, the gaseous refrigerant with the first temperature and pressure increase is discharged and then moves through the communication pipe, and after combining with the medium-pressure gaseous refrigerant (first injection) delivered from the third indoor heat exchanger (43) (internal heat exchanger for supercooling), the temperature is lowered and then introduced into the second stage inlet, and the gaseous refrigerant with the temperature and pressure increase is discharged through the second compression process.

[0293] The refrigerant discharged through the first four-way valve (21) (On) is combined with the medium-pressure gaseous refrigerant (secondary injection) delivered from the second indoor heat exchanger (42) (internal heat exchanger for injection) and then, after a temperature drop, is introduced into the first stage inlet of the second compressor (12).

[0294] The gaseous refrigerant that has been heated and pressurized after the third compression in the first stage of the second compressor (12) is introduced into the second stage inlet through the communication pipe, and the high-temperature gaseous refrigerant that has been heated and pressurized after the final fourth compression is discharged.

[0295] In this way, by driving the plurality of turbo compressors (11, 12) in series to compress the refrigerant, the compression efficiency is improved compared to the existing two-stage split compression of the refrigerant, and by reducing the compression ratio of each compressor to avoid the surge region, it is possible to improve the reliability of the compressor and induce stable continuous heating operation.

[0296] All high temperature and high pressure gaseous refrigerants are radiated to the indoor air side in the shell and tube heat exchanger (71) and then converted into medium temperature and high pressure liquid refrigerants and discharged to the indoor phase separator (61) and the indoor expansion valve (50).

[0297] At this time, the bypass solenoid valve (6111) of the indoor separator (61) can be closed to prevent the flow of refrigerant.

[0298] A portion of the medium-temperature, high-pressure liquid refrigerant expands to the intermediate pressure of the first stage inlet of the second compressor (12) in the first indoor heat exchanger (41) (internal heat exchanger for gas bearing) after branching, and then heat exchanges with the medium-temperature, high-pressure liquid refrigerant (primary subcooling of the liquid refrigerant) and then vaporizes, and then cools the motors of each of the plurality of turbo compressors (11, 12) through inverter refrigerant cooling in the cooler (80), and supplies a portion of the refrigerant to the gas bearing side of the mechanism, and then combines with the refrigerant on the first stage inlet side of each.

[0299] In this way, by supplying the refrigerant for the gas bearing at a low or medium pressure on the first stage inlet side of each compressor (11, 12) in a high-pressure state at the condensation outlet, stable refrigerant supply is possible without problems such as backflow, and the inflow of incompressible liquid refrigerant due to the refrigerant vaporized in the internal heat exchanger for the gas bearing is prevented, thereby enabling stable management of the required pressure of the gas bearing. In addition, by controlling the bypass refrigerant flow rate based on the superheat degree at the outlet of the internal heat exchanger, it is possible to minimize performance degradation due to excessive refrigerant bypass (ⓛ in FIG. 12).

[0300] Some of the first-stage supercooled medium-temperature, high-pressure liquid refrigerant expands to the intermediate pressure at the inlet side of the first stage of the second compressor (12) in the second indoor heat exchanger (42) (internal heat exchanger for injection) after branching, and then heat-exchanges with the medium-temperature, high-pressure liquid refrigerant (secondary supercooling of the liquid refrigerant) and becomes vaporized, and is combined with the medium-temperature, medium-pressure gaseous refrigerant discharged from the second-stage discharge side of the first compressor (11) and flows into the first-stage inlet side of the second compressor (12).

[0301] Some of the secondary supercooled medium-temperature, high-pressure liquid refrigerant is expanded to the intermediate pressure at the discharge side of the first stage of the first compressor (11) in the third indoor heat exchanger (43 (internal heat exchanger for supercooling) after branching, and then heat-exchanged with the medium-temperature, high-pressure liquid refrigerant (tertiary supercooling of the liquid refrigerant) and then vaporized, and is combined with the medium-temperature, medium-pressure gaseous refrigerant discharged from the discharge side of the first stage of the first compressor (11) and introduced into the second stage inlet of the first compressor (11).

[0302] In this way, through the 1st / 2nd injection, the high pressure is increased by increasing the refrigerant flow rate on the condenser side through two injections based on the same compressor rotation speed, thereby improving the heating capacity and efficiency.

[0303] In addition, by inducing a decrease in the enthalpy at the evaporator inlet through two additional subcoolings of the medium-temperature liquid refrigerant through 1 / 2 injections, high-efficiency operation becomes possible through an increase in the evaporation heat by the amount of increase in △h of the evaporator (② of Fig. 12).

[0304] The medium-temperature, high-pressure liquid refrigerant that is finally subcooled in the third indoor heat exchanger (43) is expanded to low pressure in the outdoor expansion valve (32) and then converted into a two-phase refrigerant, and then introduced into the outdoor phase separator (33).

[0305] Inside the above outdoor phase separator (33), the liquid refrigerant among the two-phase refrigerants is accumulated to the lower part of the outdoor phase separator (33) by gravity, and the gaseous refrigerant is separated to the upper part. The gaseous refrigerant separated to the upper part bypasses the outdoor heat exchanger (31) (outdoor evaporator) and is combined toward the discharge portion, and the liquid refrigerant accumulated at the lower part of the outdoor phase separator (33) absorbs heat from the outside air in the outdoor heat exchanger (31) and then turns into gas and is discharged.

[0306] By inducing the dryness of the refrigerant flowing into the outdoor heat exchanger (31) corresponding to the evaporator while passing through the outdoor phase separator (33) before the low-temperature, low-pressure two-phase refrigerant after expansion in the outdoor expansion valve (32) passes through the outdoor phase separator (33) before flowing into the evaporator, the dryness of the refrigerant is induced to be as close as possible to the saturated liquid line, thereby increasing the evaporation heat by increasing the evaporator △h through inducing an additional decrease in the enthalpy at the evaporator inlet, and by bypassing the gaseous refrigerant as much as the dryness before flowing into the evaporator to the evaporator outlet, the refrigerant pressure loss due to the flowing gas within the evaporator can be minimized, thereby increasing the evaporation heat (③ of FIG. 12).

[0307] Thereafter, all low-temperature, low-pressure gaseous refrigerant that has passed through the outdoor phase separator (33) and the outdoor heat exchanger (31) is introduced into the accumulator (13), and after being phase separated / converted in the accumulator (13), is introduced into the first stage inlet of the first compressor (11).

[0308] <Condition 4>

[0309] When the above driving conditions correspond to the fourth condition, the driving results may be as shown in Fig. 13, and the PH diagram comparing the driving results with the existing driving results may be as shown in Fig. 14.

[0310] The above air conditioning system (100) can be operated as shown in Fig. 13 to circulate the refrigerant when the operation corresponds to the defrosting operation.

[0311] The above first four-way valve (21) can switch the flow path so that the second stage discharge port of one compressor (11) among the plurality of turbo compressors (11, 12) and the inlet port of the outdoor heat exchanger (31) are connected, and the first stage inlet port of one compressor (11) and the first stage inlet port of the other compressor (12) are connected.

[0312] Accordingly, the plurality of turbo compressors (11, 12) can be driven in parallel to compress the refrigerant.

[0313] The second four-way valve (22) can switch the flow path so that the discharge port of the shell-and-tube heat exchanger (71) and the inlet port of the accumulator (13) of the plurality of turbo compressors (11, 12) are connected, and the discharge port of the second stage of the other compressor (12) and the inlet port of the outdoor heat exchanger (31) are connected.

[0314] Accordingly, the plurality of turbo compressors (11, 12) can compress the refrigerant so that the refrigerant circulates according to the above-described operation.

[0315] The above plurality of turbo compressors (11, 12) can compress refrigerant in the first and second stages, respectively, with the first compressor (11) and the other compressor (12), and deliver the refrigerant compressed in two stages from the second-stage discharge portion of the first compressor (11) and the second-stage discharge portion of the other compressor (12) to the outdoor heat exchanger (31).

[0316] The above-mentioned plurality of indoor heat exchangers (41, 42, 43) can perform heat exchange in the adjacent heat exchanger (41) by opening the inlet valve (411) of the heat exchanger (41) adjacent to the outdoor heat exchanger (31).

[0317] That is, during the above-described operation, heat exchange may occur only in the first indoor heat exchanger (41).

[0318] The first indoor heat exchanger (41) cools the vaporized refrigerant by transferring it to the cooler (80), and the refrigerant cooled in the cooler (80) passes through the internal passages of each of the plurality of turbo compressors (11, 12) and is transferred to the first stage inlet, thereby cooling the motors of each of the plurality of turbo compressors (11, 12) and supplying some of the refrigerant to the gas bearing.

[0319] At this time, the solenoid valves (111, 121) of the first compressor (11) and the second compressor (12) can be operated in a closed state to prevent the refrigerant from being delivered from the third indoor heat exchanger (43) to the second stage inlet of each of the first compressor (11) and the second compressor (12).

[0320] The specific operation of the air conditioning system (100) in this case and the results thereof are described below with reference to FIG. 14.

[0321] Low-temperature and low-pressure gaseous refrigerant is separately introduced into the first stage of the first compressor (11) and the first stage of the second compressor (12), and after the first compression, the gaseous refrigerant is discharged as a first temperature- and pressure-increased gaseous refrigerant, and then introduced into the second-stage inlet through a communication pipe, and through the second compression process, the final pressurized high-temperature and high-pressure gaseous refrigerant is discharged.

[0322] In this way, by operating the above-mentioned multiple turbo compressors (11, 12) in parallel, the compressor efficiency can be improved due to the improved compression efficiency when the load is distributed compared to the existing single compressor.

[0323] All high-temperature, high-pressure gaseous refrigerants are introduced into the outdoor heat exchanger (31) and then radiated to the atmosphere to be defrosted. After radiating the heat, they are converted into medium-temperature, high-pressure liquid refrigerants and discharged to the outdoor phase separator (33) and the outdoor expansion valve (32).

[0324] At this time, the bypass solenoid valve (331) of the outdoor phase separator (33) can be closed to prevent the flow of refrigerant, and the fan of the outdoor heat exchanger (31) can be turned off.

[0325] A portion of the medium-temperature, high-pressure liquid refrigerant expands to the intermediate pressure of the first stage inlet of the second compressor (12) in the first indoor heat exchanger (41) (internal heat exchanger for gas bearing) after branching, and then heat exchanges with the medium-temperature, high-pressure liquid refrigerant (primary subcooling of the liquid refrigerant) and then vaporizes, and then cools the motors of each of the plurality of turbo compressors (11, 12) through inverter refrigerant cooling in the cooler (80), and supplies a portion of the refrigerant to the gas bearing side of the mechanism, and then combines with the refrigerant on the first stage inlet side of each.

[0326] In this way, by supplying the refrigerant for the gas bearing at a low or medium pressure on the first stage inlet side of each compressor (11, 12) in a high-pressure state at the condensation outlet, stable refrigerant supply is possible without problems such as backflow, and the inflow of incompressible liquid refrigerant due to the refrigerant vaporized in the internal heat exchanger for the gas bearing is prevented, thereby enabling stable management of the required pressure of the gas bearing.

[0327] Meanwhile, the inlet valve (421) of the second indoor heat exchanger (42) and the inlet valve (431) of the third indoor heat exchanger (43) are each fully closed to prevent the flow of refrigerant in the second indoor heat exchanger (42) and the third indoor heat exchanger (43).

[0328] This is to prevent the flow of refrigerant, as the high / low pressure of the cycle during freezing is in a state of rapid change, and there is a high possibility of wet compression due to rapid change in injection flow rate during injection.

[0329] The medium-temperature, high-pressure liquid refrigerant that is finally subcooled in the first indoor heat exchanger (41) is expanded to low pressure in the indoor expansion valve (50) and then converted into a two-phase refrigerant, and then introduced into the indoor phase separator (61).

[0330] Inside the indoor phase separator (61), the liquid refrigerant among the two-phase refrigerants is accumulated toward the bottom of the indoor phase separator (61) by gravity, and the gaseous refrigerant is separated toward the top. The gaseous refrigerant separated toward the top bypasses the shell-and-tube heat exchanger (71) (shell-tube evaporator) and is combined toward the discharge side. The liquid refrigerant accumulated at the bottom of the indoor phase separator (61) absorbs heat from cold water in the shell-and-tube heat exchanger (71) and then turns into gas and is discharged.

[0331] By inducing the dryness of the refrigerant flowing into the shell-and-tube heat exchanger (71) corresponding to the evaporator while passing through the indoor phase separator (61) before the low-temperature, low-pressure two-phase refrigerant after expansion in the indoor expansion valve (50) is introduced into the evaporator, the dryness of the refrigerant is brought close to the saturated liquid line, thereby increasing the evaporator △h through inducing an additional decrease in the enthalpy at the evaporator inlet, thereby improving the cooling capacity. In addition, by bypassing the gaseous refrigerant as much as the dryness before introduction into the evaporator to the evaporator outlet as much as possible, the refrigerant pressure loss due to the introduced gaseous phase within the evaporator can be minimized, thereby improving the cooling capacity (ⓛ in FIG. 14).

[0332] By holding the liquid refrigerant in the above indoor phase separator (61) in this way, it is possible to prevent moisture compression due to excessive inflow of liquid refrigerant, and it is possible to prevent moisture compression by vaporizing the refrigerant through heat absorption in the evaporator.

[0333] After this, all low-temperature, low-pressure gaseous refrigerant that has passed through the indoor phase separator (61) and the shell-and-tube heat exchanger (71) is introduced into the accumulator (13), and after being phase separated / converted in the accumulator (13), is introduced into the first stage inlet of the first compressor (11).

[0334] Although the above-described embodiment of the air conditioning system (100) has been described so far, the described embodiment can be modified in various ways without departing from the scope of the present invention, and the scope of the present invention should not be limited to the described embodiment, but should be determined not only by the claims described below but also by equivalents of the claims.

Claims

1. Multiple turbo compressors that compress the refrigerant in two stages; A first four-way valve that switches the flow path of refrigerant flowing into or discharged from the plurality of turbocompressors depending on whether the plurality of turbocompressors are driven in series or in parallel; A second four-way valve that switches the flow path of the refrigerant depending on whether cooling operation, heating operation or defrosting operation is in progress; An outdoor heat exchanger connected to at least one of the above plurality of turbo compressors, in which heat exchange of the refrigerant is performed; An outdoor expansion valve connected to the outdoor heat exchanger, through which the delivered refrigerant expands; A plurality of internal heat exchangers connected to the above outdoor expansion valve and through which heat exchange of the refrigerant takes place; An indoor expansion valve connected to the plurality of internal heat exchangers, through which the delivered refrigerant expands; An indoor phase separator connected to the above indoor expansion valve and separating the phase of the delivered refrigerant; and A shell-and-tube heat exchanger connected to the above-mentioned phase separator and the plurality of turbo compressors, in which heat exchange of the delivered refrigerant is performed. Including, The above plurality of turbo compressors, the first four-way valve and the second four-way valve, An air conditioning system characterized in that the operation is performed differently depending on the operating conditions, such as whether the cooling operation, the heating operation, or the defrosting operation, and the outdoor temperature condition, and the refrigerant circulates differently depending on the operating conditions.

2. In paragraph 1, The above plurality of turbo compressors, An air conditioning system characterized by having different capacities.

3. In paragraph 1, The above first four-way valve, A first valve stage connected to the inlet of a first stage of one of the plurality of turbo compressors; A second valve stage connected to the inlet of each of the plurality of turbo compressors; A third valve stage connected to the discharge port of the second stage of the above compressor; and The fourth valve connected to the inlet of the above outdoor heat exchanger Including, An air conditioning system characterized in that each of the first to fourth valve stages is opened and closed, or any two or more of them are connected.

4. In paragraph 1, The above second four-way valve, A first valve stage connected to the discharge port of each of the two stages of the plurality of turbo compressors; A second valve stage connected to the discharge portion of the above shell-and-tube heat exchanger; A third valve stage connected to the inlet of the accumulator of the plurality of turbo compressors; and The fourth valve connected to the inlet of the above outdoor heat exchanger Including, An air conditioning system characterized in that each of the first to fourth valve stages is opened and closed, or any two or more of them are connected.

5. In paragraph 1, An outdoor phase separator, which is arranged between the outdoor heat exchanger and the outdoor expansion valve, separates the phase of the refrigerant delivered from the outdoor expansion valve during the heating operation and delivers the separated gaseous refrigerant to the plurality of turbo compressors. An air conditioning system characterized by further comprising:

6. In paragraph 1, The above multiple indoor heat exchangers are, It comprises a first indoor heat exchanger, a second indoor heat exchanger and a third indoor heat exchanger arranged in series, Each of the first indoor heat exchanger to the third indoor heat exchanger, Including an inlet valve that opens and closes the inlet, An air conditioning system characterized in that the refrigerant transferred from the previous heat exchanger undergoes heat exchange in one or more indoor heat exchangers according to the operation of the above inlet valve.

7. In paragraph 6, The above first indoor heat exchanger is, An air conditioning system characterized in that the inlet valve performs heat exchange of refrigerant during all of the cooling operation, the heating operation, and the defrosting operation.

8. In paragraph 7, When heat exchange is performed in the first indoor heat exchanger, a cooler that cools the vaporized refrigerant in the first indoor heat exchanger and delivers it to the first stage inlet of each of the plurality of turbo compressors An air conditioning system characterized by further comprising:

9. In paragraph 1, If the above driving status corresponds to the above cooling driving status and the above temperature condition is 27 [℃] or higher, The above first four-way valve, The flow path is changed so that the second stage discharge port of one compressor among the plurality of turbo compressors is connected to the first stage inlet port of the other compressor, and the inlet port of the outdoor heat exchanger is connected to the discharge port of the shell-and-tube heat exchanger. The above second four-way valve, An air conditioning system characterized in that the discharge port of the shell-and-tube heat exchanger and the inlet port of the accumulator of the plurality of turbo compressors are connected, and the flow path is switched so that the discharge port of the second stage of the other compressor and the inlet port of the outdoor heat exchanger are connected.

10. In paragraph 9, If the above driving status corresponds to the above cooling driving status and the above temperature condition is 27 [℃] or higher, The above plurality of turbo compressors, An air conditioning system characterized in that the refrigerant is compressed in the order of the first and second stages of the above compressor, and the first and second stages of the other compressor, and the refrigerant compressed in four stages is delivered from the discharge port of the second stage of the other compressor to the outdoor heat exchanger.

11. In paragraph 9, If the above driving status corresponds to the above cooling driving status and the above temperature condition is 27 [℃] or higher, The above multiple indoor heat exchangers are, Each inlet valve is opened, and heat exchange takes place in each. One of the ones placed in the middle, The vaporized refrigerant is delivered to the first stage inlet of the above compressor, One placed before the above indoor expansion valve, An air conditioning system characterized in that the vaporized refrigerant is delivered to the second stage inlet of the above compressor.

12. In paragraph 1, If the above driving corresponds to the above cooling driving and the above temperature condition is less than 27 [℃], The above first four-way valve, The flow path is switched so that the second stage discharge port of one compressor among the plurality of turbo compressors and the inlet port of the outdoor heat exchanger are connected, and the first stage inlet port of the one compressor and the first stage inlet port of the other compressor are connected. The above second four-way valve, An air conditioning system characterized in that the discharge port of the shell-and-tube heat exchanger and the inlet port of the accumulator of the plurality of turbo compressors are connected, and the flow path is switched so that the discharge port of the second stage of the other compressor and the inlet port of the outdoor heat exchanger are connected.

13. In paragraph 12, If the above driving corresponds to the above cooling driving and the above temperature condition is less than 27 [℃], The above plurality of turbo compressors, An air conditioning system characterized in that the first compressor and the second compressor compress the refrigerant in the first and second stages, respectively, and deliver the refrigerant compressed in the second stage from the second stage discharge portion of the first compressor and the second stage discharge portion of the second compressor to the outdoor heat exchanger.

14. In paragraph 12, If the above driving corresponds to the above cooling driving and the above temperature condition is less than 27 [℃], The above multiple indoor heat exchangers are, The inlet valves of each of the two heat exchangers arranged at both ends are opened, so that heat exchange occurs in each of the two heat exchangers. One of the two heat exchangers above is placed before the indoor expansion valve, An air conditioning system characterized in that the vaporized refrigerant is delivered to each of the two-stage inlet of the first compressor and the two-stage inlet of the other compressor.

15. In paragraph 1, If the above driving corresponds to the above heating driving, The above first four-way valve, The second stage discharge port of one compressor among the plurality of turbo compressors is connected to the first stage inlet port of the other compressor, and the flow path is changed so that the inlet port of the outdoor heat exchanger is connected to the discharge port of the shell-and-tube heat exchanger. The above second four-way valve, The inlet port of the outdoor heat exchanger and the inlet port of the accumulator of the plurality of turbo compressors are connected, and the flow path is changed so that the discharge port of the second stage of the other compressor and the discharge port of the shell-and-tube heat exchanger are connected. An air conditioning system characterized in that the refrigerant circulates in the opposite direction to the direction during the cooling operation.

16. In paragraph 15, If the above driving corresponds to the above heating driving, The above plurality of turbo compressors, An air conditioning system characterized in that the refrigerant is compressed in the order of the first and second stages of the above compressor, the first and second stages of the other compressor, and the refrigerant compressed in four stages is delivered from the discharge port of the second stage of the other compressor to the shell-and-tube heat exchanger.

17. In paragraph 16, If the above driving corresponds to the above heating driving, The above multiple indoor heat exchangers are, Each inlet valve is opened, and heat exchange takes place in each. One of the ones placed in the middle, The vaporized refrigerant is delivered to the first stage inlet of the above compressor, One placed before the above indoor expansion valve, An air conditioning system characterized in that the vaporized refrigerant is delivered to the second stage inlet of the above compressor.

18. In paragraph 1, If the above driving is equivalent to the above driving, The above first four-way valve, The flow path is switched so that the second stage discharge port of one compressor among the plurality of turbo compressors and the inlet port of the outdoor heat exchanger are connected, and the first stage inlet port of the one compressor and the first stage inlet port of the other compressor are connected. The above second four-way valve, An air conditioning system characterized in that the discharge port of the shell-and-tube heat exchanger and the inlet port of the accumulator of the plurality of turbo compressors are connected, and the flow path is switched so that the discharge port of the second stage of the other compressor and the inlet port of the outdoor heat exchanger are connected.

19. In paragraph 18, If the above driving is equivalent to the above driving, The above plurality of turbo compressors, An air conditioning system characterized in that the first compressor and the second compressor compress the refrigerant in the first and second stages, respectively, and deliver the refrigerant compressed in the second stage from the second stage discharge portion of the first compressor and the second stage discharge portion of the second compressor to the outdoor heat exchanger.

20. In paragraph 18, If the above driving is equivalent to the above driving, The above multiple indoor heat exchangers are, An air conditioning system characterized in that the inlet valve of the heat exchanger adjacent to the outdoor heat exchanger is opened, and heat exchange occurs in the adjacent heat exchanger.

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