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 cold system of 150 [RT] or less, a higher pressure and condensing temperature are required to dissipate heat into the air of the condenser, and at this time, the operating conditions that are 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 addition, when operating the cooling system at low temperatures in the winter, the reduction in the heat transfer area cannot be controlled, which induces a drop in high pressure (condensing temperature) through excessive heat dissipation, causing the compressor to turn off frequently, which causes a problem of interrupting the continuous supply of cooling power.

[0010] 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 due to the increase in high pressure. In the summer when the outside temperature rises and the cooling overload occurs, the degree and frequency of this surging phenomenon may become more severe and increase.

[0011] 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.

[0012] [Prior Art Literature]

[0013] [Patent Document]

[0014] (Patent Document 1) US 10794619 B2

[0015] The present invention aims to improve the limitations of the prior art as described above.

[0016] Accordingly, the present specification provides an embodiment in which an air-cooled cold storage system of 150 [RT] or less can be operated stably, efficiently, and with high performance.

[0017] Specifically, the present invention aims to provide an example of an air-cooled, cold-type, 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.

[0018] 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.

[0019] In addition, the present invention provides an embodiment in which the heat transfer area of ​​an outdoor heat exchanger and an evaporator can be freely varied during low-temperature cooling operation in winter, thereby controlling the heat dissipation amount and evaporation heat amount (cooling capacity), thereby enabling continuous cooling operation through stable maintenance of high and low pressures.

[0020] In addition, we aim to provide an example in which year-round high-efficiency cold-cycle operation can be achieved through gaseous refrigerant bypass through an evaporator front-end phase separator.

[0021] In addition, the refrigerant circuit of the gas bearing system of the compressor is dualized to improve the reliability of the gas bearing system through rapid refrigerant transfer when restarting from a balanced pressure state after a stop, and to provide an embodiment that 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.

[0022] 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.

[0023] 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 four-way valve that switches a flow path of refrigerant flowing into or discharged from the plurality of turbocompressors, at least one outdoor heat exchanger in which heat is exchanged with refrigerant delivered from at least one of the plurality of turbocompressors, a plurality of internal heat exchangers in which heat is exchanged with refrigerant delivered from the at least one outdoor heat exchanger, an expansion valve in which expansion of the refrigerant delivered from the plurality of internal heat exchangers occurs, a phase separator that separates the phases of the refrigerant delivered from the expansion valves and transfers the separated gaseous refrigerant to the plurality of turbocompressors, and at least one shell-and-tube heat exchanger in which heat is exchanged with liquid refrigerant delivered from the phase separator and transfers the heat-exchanged refrigerant to the plurality of turbocompressors, wherein the plurality of turbocompressors and the four-way valve operate differently depending on operating conditions such as whether cooling / heating operation is performed and an outdoor temperature state, so that the refrigerant circulates differently depending on the operating conditions.

[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 four-way valve includes a first valve stage connected to an inlet of a first stage of one of the plurality of turbo compressors, a second valve stage connected to an inlet of each of the plurality of turbo compressors, 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 one or more of the outdoor heat exchangers, 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, when the at least one outdoor heat exchanger is comprised of a plurality of units, the apparatus comprises a first outdoor heat exchanger, a second outdoor heat exchanger, and a third outdoor heat exchanger arranged in parallel, and each of the first to third outdoor heat exchangers includes an inlet valve that opens and closes an inlet portion, so that refrigerant received from at least one of the plurality of turbocompressors can undergo heat exchange in at least one outdoor heat exchanger according to operation of the inlet valve.

[0028] In an embodiment, one or more of the plurality of indoor heat exchangers may transfer at least a portion of the heat-exchanged refrigerant to one or more of 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, 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 turbo compressors.

[0031] In an embodiment, when the at least one shell-and-tube heat exchanger is formed in plurality, a first shell-and-tube heat exchanger, a second shell-and-tube heat exchanger, and a third shell-and-tube heat exchanger are arranged in parallel, and each of the first shell-and-tube heat exchanger to the third shell-and-tube heat exchanger includes an inlet valve that opens and closes an inlet portion, so that heat exchange can be performed on the refrigerant received from the phase separator in the at least one shell-and-tube heat exchanger according to the operation of the inlet valve.

[0032] In an embodiment, when the above-described operation corresponds to a cooling operation and the temperature state is 27 [℃] or higher, the four-way valve switches the flow path so that a second-stage discharge port of one compressor among the plurality of turbocompressors and a first-stage inlet port of the other compressor are connected, and an inlet port of the one or more outdoor heat exchangers and a discharge port of the one or more shell-and-tube heat exchangers are connected, and the plurality of turbocompressors 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 the refrigerant compressed in four stages can be delivered from the second-stage discharge port of the other compressor to the one or more outdoor heat exchangers.

[0033] In an embodiment, when the above driving corresponds to cooling driving and the temperature condition is 27 [℃] or higher, each of the one or more outdoor heat exchangers and the one or more shell-and-tube heat exchangers has its respective inlet valves opened so that heat exchange can take place therein.

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

[0035] In an embodiment, when the above-described operation corresponds to a cooling operation and the temperature state is less than 27 [℃], the four-way valve switches the flow path so that a second-stage discharge port of one compressor among the plurality of turbocompressors and an inlet port of the one or more outdoor heat exchangers are connected, and a first-stage inlet port of the one compressor and a first-stage inlet port of the other compressor are connected, and the plurality of turbocompressors can compress refrigerant in the first and second stages, respectively, and deliver the refrigerant compressed in two stages at each of the second-stage discharge port of the one compressor and the second-stage discharge port of the other compressor to the one or more outdoor heat exchangers.

[0036] In an embodiment, when the above driving corresponds to cooling driving and the temperature condition is less than 27 [℃], each of the one or more outdoor heat exchangers and the one or more shell-and-tube heat exchangers may have their respective inlet valves opened so that heat exchange can occur therein.

[0037] In an embodiment, when the above operation corresponds to cooling operation and the 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 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 above-described operation corresponds to heating operation and the temperature state is 0 [℃] or higher, the four-way valve switches the flow path so that the second-stage discharge port of one compressor having a larger capacity among the plurality of turbocompressors is connected to the inlet port of the one or more outdoor heat exchangers, and the first-stage inlet port of the one compressor is connected to the first-stage inlet port of the other compressor, and the plurality of turbocompressors can compress the refrigerant in the first and second stages in that order with the one compressor and the other compressor not being driven, so that the refrigerant compressed in the second stage at the second-stage discharge port of the one compressor can be delivered to the one or more outdoor heat exchangers.

[0039] In an embodiment, when the above driving corresponds to heating driving and the temperature state is 0 [℃] or higher, each of the one or more outdoor heat exchangers and the one or more shell-and-tube heat exchangers is formed in plurality, and one inlet valve is not opened, and the remaining inlet valves are opened, so that heat exchange can be performed in each of the open heat exchangers.

[0040] In an embodiment, when the above operation corresponds to cooling operation and the temperature state is 0 [℃] or higher, 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 expansion valve can transfer the vaporized refrigerant to the second stage inlet of the compressor.

[0041] In an embodiment, when the above-described operation corresponds to heating operation and the temperature state is less than 0 [℃], the four-way valve switches the flow path so that the first stage inlet port of a compressor having a large capacity among the plurality of turbo compressors is connected to the first stage inlet port of the other compressor, and the plurality of turbo compressors can compress the refrigerant in the first and second stages sequentially while the one compressor is not operated, and deliver the refrigerant compressed in the second stage from the second stage discharge port of the other compressor to the one or more outdoor heat exchangers.

[0042] In an embodiment, when the above driving corresponds to heating driving and the temperature state is less than 0 [℃], each of the one or more outdoor heat exchangers and the one or more shell-and-tube heat exchangers is formed in multiples, and one inlet valve is opened and the remaining inlet valves are not opened, so that heat exchange can be performed in each of the open heat exchangers.

[0043] In an embodiment, when the above driving corresponds to heating driving and the temperature state is less than 0 [℃], the plurality of indoor heat exchangers may have an inlet valve of one heat exchanger positioned adjacent to the one or more outdoor heat exchangers opened so that heat exchange can take place in the one heat exchanger.

[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, during low-temperature cooling operation in winter, the heat transfer area of ​​the outdoor heat exchanger and evaporator can be freely varied to control the heat dissipation amount and evaporation heat amount (cooling capacity), thereby enabling continuous cooling operation through stable maintenance of high and low pressures.

[0048] 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.

[0049] In addition, the refrigerant circuit of the compressor's gas bearing system is dualized, which improves the reliability of the gas bearing system through rapid refrigerant transfer when restarting from a balanced pressure state after a stop, and during continuous operation, high-efficiency operation of the gas bearing system is achieved with refrigerant superheated to a medium temperature through the internal heat exchanger for the gas bearing at the condenser outlet and 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 cold storage system.

[0067] 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).

[0068] 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).

[0069] Accordingly, in the air conditioning system (100), the refrigerant may be circulated in the following order: 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).

[0070] The above compression unit (10) may include a plurality of compressors (11, 12) that compress the refrigerant.

[0071] The above compressor (11, 12) may be a turbo compressor that compresses the refrigerant in two stages.

[0072] 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.

[0073] 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).

[0074] The compression unit (10) may have an inlet portion connected to a discharge portion of the shell-and-tube heat exchange unit (70), and the discharge portion may be connected to an inlet portion of the external heat exchange unit (30).

[0075] That is, the compression unit (10) may be connected to a pipe whose discharge portion is connected to the inlet portion of the external heat exchange unit (30), and whose inlet portion may be connected to a pipe whose discharge portion is connected to the shell-and-tube heat exchange unit (70).

[0076] Accordingly, the compression unit (10) can 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).

[0077] The above valve unit (20) may include a four-way valve that switches the flow path of refrigerant flowing into or discharged from the plurality of turbo compressors (11, 12).

[0078] The above external heat exchanger (30) may include one or more outdoor heat exchangers (31) installed outdoors and in which heat exchange of the refrigerant transferred from the compression unit (10) is performed.

[0079] The above outdoor heat exchanger (31) may correspond to a condenser.

[0080] The above external heat exchanger (30) may preferably include a plurality of outdoor heat exchangers, in which case the plurality of outdoor heat exchangers may be connected in parallel.

[0081] 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).

[0082] The external heat exchange unit (30) may have an inlet portion connected to a discharge portion of the compression unit (10), and the discharge portion may be connected to an inlet portion of the internal heat exchange unit (40).

[0083] That is, the external heat exchange unit (30) may be connected to a pipe whose discharge portion is connected to the inlet portion of the internal heat exchange unit (40), and whose inlet portion may be connected to a pipe whose discharge portion is connected to the compression unit (10).

[0084] Accordingly, the external heat exchange unit (30) can receive refrigerant from the compression unit (10), perform heat exchange, and then transfer the heat-exchanged refrigerant to the internal heat exchange unit (40).

[0085] The above internal heat exchanger (40) may include a plurality of indoor heat exchangers (41, 42) installed indoors and in which heat exchange of the refrigerant transferred from the external heat exchanger (30) is performed.

[0086] The above internal heat exchanger (40) may preferably include two or more indoor heat exchangers (41, 42), in which case the two or more indoor heat exchangers (41, 42) may be connected in series.

[0087] 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).

[0088] The internal heat exchanger (40) may have an inlet portion connected to a discharge portion of the external heat exchanger (30), and the discharge portion may be connected to an inlet portion of the expansion portion (50).

[0089] That is, the internal heat exchange unit (40) may be connected to a pipe whose discharge portion is connected to the inlet portion of the expansion unit (50), and whose inlet portion may be connected to a pipe whose discharge portion is connected to the discharge portion of the external heat exchange unit (30).

[0090] Accordingly, the internal heat exchange unit (40) can receive refrigerant from the external heat exchange unit (30), perform heat exchange, and then transfer the heat-exchanged refrigerant to the expansion unit (50).

[0091] The above expansion unit (50) may include an expansion valve installed indoors to allow expansion of the refrigerant transferred from the internal heat exchange unit (40).

[0092] 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).

[0093] The above expansion unit (50) may have an inlet portion connected to a discharge portion of the internal heat exchange unit (40), and the discharge portion may be connected to an inlet portion of the phase separation unit (60).

[0094] That is, the expansion unit (50) may be connected to a pipe in which the discharge unit is connected to the inlet unit of the phase separation unit (60), and the inlet unit may be connected to a pipe in which the discharge unit of the internal heat exchange unit (40) is connected.

[0095] Accordingly, the expansion unit (50) can receive refrigerant from the internal heat exchange unit (40), perform heat exchange, and then transfer the heat-exchanged refrigerant to the phase separation unit (60).

[0096] The above phase separation unit (60) may include a phase separator that separates the phase of the refrigerant delivered from the expansion unit (50) and delivers the separated gaseous refrigerant to the compression unit (10).

[0097] 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).

[0098] The above-mentioned phase separation unit (60) may have an inlet portion connected to a discharge portion of the expansion unit (50), and the discharge portion may be connected to the shell-and-tube heat exchange unit (70) and the inlet portion of the compression unit (10).

[0099] That is, the phase separation unit (60) may be connected to a pipe whose discharge portion is connected to the shell-and-tube heat exchange unit (70) and the inlet portion of the compression unit (10), and whose inlet portion may be connected to a pipe whose discharge portion is connected to the expansion unit (50).

[0100] Accordingly, the phase separation unit (60) receives the refrigerant from the expansion unit (50), and after phase separation into gaseous and liquid phases, the separated gaseous refrigerant is transferred to the compression unit (10), and the liquid refrigerant is transferred to the shell-and-tube heat exchange unit (70).

[0101] The above shell-and-tube heat exchanger (70) may include one or more shell-and-tube heat exchangers (71) installed indoors, which 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).

[0102] The above shell and tube heat exchanger (71) may correspond to an evaporator.

[0103] The above shell-and-tube heat exchanger (70) may preferably include a plurality of shell-and-tube heat exchangers, and in this case, the plurality of shell-and-tube heat exchangers may be connected in parallel.

[0104] 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).

[0105] The above shell and tube heat exchanger (70) may have an inlet portion connected to a discharge portion of the phase separation portion (60), and the discharge portion may be connected to an inlet portion of the compression portion (10).

[0106] That is, the shell and tube heat exchanger (70) may have a discharge portion connected to a pipe connected to the inlet portion of the compression portion (10), and an inlet portion connected to a pipe connected to the discharge portion of the phase separation portion (60).

[0107] Accordingly, the shell and tube heat exchange unit (70) can receive refrigerant from the phase separation unit (60), perform heat exchange, and then transfer the heat-exchanged refrigerant to the compression unit (10).

[0108] 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.

[0109] 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 four-way valve (20) for switching the flow path of refrigerant flowing into or discharged from the plurality of turbo compressors (11, 12); one or more outdoor heat exchangers (31, 32, 33) for heat exchange of refrigerant delivered from one or more of the plurality of turbo compressors (11, 12); a plurality of internal heat exchangers (41, 42, 43) for heat exchange of refrigerant delivered from the one or more outdoor heat exchangers (31, 32, 33); an expansion valve (50) for expansion of refrigerant delivered from the plurality of internal heat exchangers (41, 42, 43); a phase separator (61) for separating the phase of refrigerant delivered from the expansion valve and delivering the separated gaseous refrigerant to the plurality of turbo compressors (11, 12); and a phase separator (61) for It includes one or more shell-and-tube heat exchangers (71, 72, 73) that perform heat exchange of the transferred liquid refrigerant and transfer the heat-exchanged refrigerant to the plurality of turbo compressors (11, 12).

[0110] In the above air conditioning system (100), the plurality of turbo compressors (11, 12) and the four-way valve (20) operate differently depending on the operating conditions, such as whether cooling / heating operation is performed and the outdoor temperature condition, so that the refrigerant circulates differently depending on the operating conditions.

[0111] That is, the air conditioning system (100) can have different driving modes depending on the driving conditions.

[0112] For example, when the driving condition corresponds to the first condition, the vehicle can be driven in the first mode, and when the driving condition corresponds to the second condition, the vehicle can be driven in the second mode.

[0113] In this case, the first mode and the second mode may be set differently.

[0114] The above driving status may be cooling driving or heating driving, and the above temperature status may be the outside temperature.

[0115] The above plurality of turbo compressors (11, 12) are included in the compression unit (10) and can compress refrigerant.

[0116] Each of the above plurality of turbo compressors (11, 12) can compress the refrigerant twice and discharge it.

[0117] The above plurality of turbo compressors (11, 12) may have different capacities.

[0118] The capacity of one of the above plurality of turbo compressors (11, 12) may be 50 [%] or less of the capacity of the other.

[0119] 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.

[0120] Accordingly, the refrigerant can be compressed differently in each of the plurality of turbo compressors (11, 12).

[0121] The above plurality of turbo compressors (11, 12) can be driven one or more times to compress the refrigerant depending on the operating conditions.

[0122] 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 four-way valve (20).

[0123] 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.

[0124] 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).

[0125] 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).

[0126] 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).

[0127] 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).

[0128] 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.

[0129] 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).

[0130] The above internal euro solenoid valve (114, 124) is normally closed and can be opened when supplying refrigerant to the internal euro.

[0131] 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.

[0132] 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.

[0133] The above four-way valve (20) 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).

[0134] The above four-way valve (20) includes a first valve stage (E) connected to the inlet of one 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 the second stage of the one compressor (11), and a fourth valve stage (C) connected to the inlet of one or more of the outdoor heat exchangers (31, 32, 33), and can open and close each of the first valve stage to the fourth valve stage (E, S, D, C) or connect any two or more of them.

[0135] 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.

[0136] Accordingly, the plurality of turbo compressors (11, 12) can be operated in series or parallel.

[0137] The above one or more outdoor heat exchangers (31, 32, 33) are included in the external heat exchange unit (30), and heat exchange of refrigerant delivered from one or more of the plurality of turbo compressors (11, 12) can be performed.

[0138] The above one or more outdoor heat exchangers (31, 32, 33) may be formed in multiples, and preferably in three or more.

[0139] When the above one or more outdoor heat exchangers (31, 32, 33) are configured in multiples, the multiple outdoor heat exchangers (31, 32, 33) can be arranged in parallel.

[0140] Accordingly, the refrigerant delivered from one or more of the plurality of turbo compressors (11, 12) may be branched and introduced into each of the plurality of outdoor heat exchangers (31, 32, 33) and then heat exchange may be performed.

[0141] When the above one or more outdoor heat exchangers (31, 32, 33) are configured in multiples, it may include a first outdoor heat exchanger (31), a second outdoor heat exchanger (32), and a third outdoor heat exchanger (33) arranged in parallel.

[0142] Each of the first to third outdoor heat exchangers (31, 32, 33) includes an inlet valve (311, 321, 331) that opens and closes an inlet port, so that refrigerant received from one or more of the plurality of turbocompressors (11, 12) can undergo heat exchange in one or more outdoor heat exchangers (31, 32, 33) according to the operation of the inlet valve.

[0143] For example, when the first inlet valve (311) provided in the first outdoor heat exchanger (31) is operated in the open state, the refrigerant flows into the first outdoor heat exchanger (31), and heat exchange of the refrigerant occurs in the first outdoor heat exchanger (31). When the second inlet valve (321) provided in the second outdoor heat exchanger (32) is operated in the close state, the refrigerant does not flow into the second outdoor heat exchanger (32), and heat exchange of the refrigerant does not occur in the second outdoor heat exchanger (32).

[0144] Each of the first outdoor heat exchanger to the third outdoor heat exchanger (31, 32, 33) may further include a check valve (312, 322, 332) for preventing backflow of the refrigerant.

[0145] The above check valve (312, 322, 332) may be a valve that prevents the backflow of the refrigerant by restricting the refrigerant to flow in only one direction.

[0146] Accordingly, the refrigerant discharged from each of the first outdoor heat exchanger to the third outdoor heat exchanger (31, 32, 33) can be transferred to the plurality of indoor heat exchangers (41, 42, 43) without reverse flow.

[0147] The above-described plurality of indoor heat exchangers (41, 42, 43) are included in the internal heat exchange unit (40), and heat exchange of refrigerant transferred from one or more of the above-described one or more outdoor heat exchangers (31, 32, 33) can be performed.

[0148] The above-mentioned plurality of indoor heat exchangers (41, 42, 43) may preferably be composed of three or more.

[0149] The above multiple indoor heat exchangers (41, 42, 43) can be arranged in series.

[0150] 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.

[0151] 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).

[0152] 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).

[0153] 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).

[0154] 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).

[0155] 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.

[0156] 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).

[0157] Accordingly, the refrigerant received from the one or more outdoor heat exchangers (31, 32, 33) 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.

[0158] The above first indoor heat exchanger (41) may be an internal heat exchanger for a gas bearing.

[0159] 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).

[0160] 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).

[0161] The above second indoor heat exchanger (42) may be an internal heat exchanger for injection.

[0162] 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.

[0163] The above third indoor heat exchanger (43) may be an internal heat exchanger for supercooling.

[0164] 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.

[0165] 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.

[0166] 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).

[0167] 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).

[0168] 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).

[0169] 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).

[0170] 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).

[0171] The above expansion valve (50) is included in the expansion unit (50), and expansion of the refrigerant transmitted from the plurality of internal heat exchangers (41, 42, 43) can be achieved.

[0172] The above-mentioned phase separator (61) is included in the phase separation unit (60) and can separate the phase of the refrigerant delivered from the expansion valve (50) into a gas phase and a liquid phase, deliver the separated gas phase refrigerant to the plurality of turbo compressors (11, 12), and deliver the separated liquid phase refrigerant to one or more shell-and-tube heat exchangers (71, 72, 73).

[0173] That is, the gaseous refrigerant separated in the phase separator (61) is bypassed to the plurality of turbo compressors (11, 12), and the liquid refrigerant is transferred to one or more shell-and-tube heat exchangers (71, 72, 73) to be subjected to heat exchange.

[0174] In this case, the phase separation unit (60) may further 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 turbo compressors (11, 12).

[0175] The above one or more shell-and-tube heat exchangers (71, 72, 73) are included in the shell-and-tube heat exchange unit (70), and heat exchange of the refrigerant transferred from the phase separator (61) can be performed.

[0176] The above one or more shell-and-tube heat exchangers (71, 72, 73) may be formed in multiples, and preferably in three or more.

[0177] When the above one or more shell-and-tube heat exchangers (71, 72, 73) are configured in multiples, the multiple shell-and-tube heat exchangers (71, 72, 73) can be arranged in parallel.

[0178] Accordingly, the refrigerant delivered through the phase separator (61) may be branched and introduced into each of the plurality of shell-and-tube heat exchangers (71, 72, 73) and then heat exchange may be performed.

[0179] When the above one or more shell-and-tube heat exchangers (71, 72, 73) are configured in plurality, it may include a first shell-and-tube heat exchanger (71), a second shell-and-tube heat exchanger (72), and a third shell-and-tube heat exchanger (73) arranged in parallel.

[0180] Each of the first shell-and-tube heat exchanger to the third shell-and-tube heat exchanger (71, 72, 73) includes an inlet valve (711, 721, 731) that opens and closes an inlet portion, so that the refrigerant received from the phase separator (61) can undergo heat exchange in one or more shell-and-tube heat exchangers (71, 72, 73) according to the operation of the inlet valve.

[0181] For example, when the first inlet valve (711) provided in the first shell-and-tube heat exchanger (71) is operated in the open position, the refrigerant flows into the first shell-and-tube heat exchanger (71), and heat exchange of the refrigerant occurs in the first shell-and-tube heat exchanger (71). When the second inlet valve (721) provided in the second shell-and-tube heat exchanger (72) is operated in the close position, the refrigerant does not flow into the second shell-and-tube heat exchanger (72), and heat exchange of the refrigerant may not occur in the second shell-and-tube heat exchanger (72).

[0182] 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).

[0183] 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).

[0184] 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).

[0185] 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).

[0186] 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.

[0187] The air conditioning system (100) including the plurality of turbo compressors (11, 12), the four-way valve (20), the one or more outdoor heat exchangers (31, 32, 33), the plurality of internal heat exchangers (41, 42, 43), the expansion valve (50), the phase separator (61) and the one or more shell-and-tube heat exchangers (71, 72, 73) can be operated to circulate refrigerant as shown in FIG. 7, FIG. 9, FIG. 11 or FIG. 13 depending on the operating conditions.

[0188] The above driving conditions can be divided into multiple conditions depending on whether the cooling / heating operation is performed and the temperature status.

[0189] The above driving conditions may include, for example, a first condition in which the driving corresponds to cooling operation and the temperature state is 27 [℃] or higher, a second condition in which the driving corresponds to cooling operation and the temperature state is less than 27 [℃], a third condition in which the driving corresponds to heating operation and the temperature state is 0 [℃] or higher, and a fourth condition in which the driving corresponds to heating operation and the temperature state is less than 0 [℃].

[0190] 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.

[0191] Below, the specific operation and the resulting results / effects for each operating condition of the air conditioning system (100) are described.

[0192] <Condition 1>

[0193] 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.

[0194] The above air conditioning system (100) can be operated as shown in Fig. 7 to circulate the refrigerant when the operation corresponds to cooling operation and the temperature state is 27 [℃] or higher.

[0195] The above four-way valve (20) can switch the flow path so that the second stage discharge port of one compressor (11) among the plurality of turbo compressors (11, 12) is connected to the first stage inlet port of the other compressor (12), and the inlet port of one or more outdoor heat exchangers (31, 32, 33) is connected to the discharge port of one or more shell-and-tube heat exchangers (71, 72, 73).

[0196] Accordingly, the plurality of turbo compressors (11, 12) can be driven in series to compress the refrigerant.

[0197] The above plurality of turbo compressors (11, 12) can compress 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 one or more outdoor heat exchangers (31, 32, 33).

[0198] Each of the above one or more outdoor heat exchangers (31, 32, 33) and the above one or more shell-and-tube heat exchangers (71, 72, 73) has its respective inlet valves (311, 321, 331, 711, 721, 731) opened, so that heat exchange can take place therein.

[0199] That is, heat exchange can be performed in both the one or more outdoor heat exchangers (31, 32, 33) and the one or more shell-and-tube heat exchangers (71, 72, 73).

[0200] 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.

[0201] 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 expansion valve (50) can transfer the vaporized refrigerant to the second stage inlet of the first compressor (11).

[0202] 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).

[0203] 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).

[0204] 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.

[0205] The specific operation of the air conditioning system (100) in this case and the results thereof are described below with reference to FIG. 8.

[0206] 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.

[0207] The refrigerant discharged through the above four-way valve (20) (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).

[0208] 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.

[0209] 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.

[0210] 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.

[0211] The inlet valves (311, 321, 331) of each of the above one or more outdoor heat exchangers (31, 32, 33) are opened, and all high-temperature, high-pressure gaseous refrigerant is radiated to the outdoor air side from each of the above one or more outdoor heat exchangers (31, 32, 33) and then converted into medium-temperature, high-pressure liquid refrigerant and discharged.

[0212] 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.

[0213] 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).

[0214] 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).

[0215] 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 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).

[0216] 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).

[0217] 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.

[0218] In addition, by minimizing compressor rotation speed restrictions through reducing compressor discharge temperature, it becomes possible to maintain cooling power under cooling overload conditions.

[0219] 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 expansion valve (50) and then converted into a two-phase refrigerant, and then flows into the phase separator (61).

[0220] Inside the phase separator (61), the liquid refrigerant among the two-phase refrigerants is accumulated toward the bottom of the phase separator (61) by gravity, and the gaseous refrigerant is separated toward the top. The gaseous refrigerant separated toward the top bypasses the one or more shell-and-tube heat exchangers (71, 72, 73) (shell-tube evaporator) and is combined toward the discharge side, and the liquid refrigerant accumulated at the bottom of the phase separator (61) passes through the inlet valves (711, 721, 731) of the one or more open shell-and-tube heat exchangers (71, 72, 73), absorbs heat from cold water in each of the one or more shell-and-tube heat exchangers (71, 72, 73), and is then discharged as a gas.

[0221] By inducing the dryness of the refrigerant flowing into the one or more shell-and-tube heat exchangers (71, 72, 73) corresponding to the evaporator while passing through the phase separator (61) after expansion in the above expansion valve (50) before flowing 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, and by bypassing the gaseous refrigerant as much as the dryness before flowing into the evaporator to the evaporator outlet, thereby minimizing the refrigerant pressure loss due to the flowing gas within the evaporator, the cooling capacity can be improved (③ of FIG. 8).

[0222] After this, all low-temperature, low-pressure gaseous refrigerants that have passed through one or more shell-and-tube heat exchangers (71, 72, 73) are introduced into the first stage inlet of the first compressor (11).

[0223] <Condition 2>

[0224] 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.

[0225] 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 [℃].

[0226] The above four-way valve (20) can switch the flow path so that the second stage discharge port of one compressor (11) among the plurality of turbo compressors (11, 12) is connected to the inlet port of one or more outdoor heat exchangers (31, 32, 33), and the first stage inlet port of one compressor (11) is connected to the first stage inlet port of the other compressor (12).

[0227] 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 one or more outdoor heat exchangers (31, 32, 33).

[0228] Accordingly, the plurality of turbo compressors (11, 12) can be driven in parallel to compress the refrigerant.

[0229] Each of the above one or more outdoor heat exchangers (31, 32, 33) and the above one or more shell-and-tube heat exchangers (71, 72, 73) has its respective inlet valves (311, 321, 331, 711, 721, 731) opened, so that heat exchange can take place therein.

[0230] That is, heat exchange can be performed in both the one or more outdoor heat exchangers (31, 32, 33) and the one or more shell-and-tube heat exchangers (71, 72, 73).

[0231] 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.

[0232] 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.

[0233] 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).

[0234] 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).

[0235] 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.

[0236] Meanwhile, in such a case, the inlet valve (421) of the second indoor heat exchanger (42) may be driven to close.

[0237] The specific operation of the air conditioning system (100) in this case and the resulting results are described below with reference to FIG. 10.

[0238] 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.

[0239] 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.

[0240] The inlet valves (311, 321, 331) of each of the above one or more outdoor heat exchangers (31, 32, 33) are opened, and all high-temperature, high-pressure gaseous refrigerant is radiated to the outdoor air side from each of the above one or more outdoor heat exchangers (31, 32, 33) and then converted into medium-temperature, high-pressure liquid refrigerant and discharged.

[0241] 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.

[0242] 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).

[0243] 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).

[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 increase in evaporator △h, thereby enabling high-efficiency operation through a decrease in compressor input energy (② of Fig. 10).

[0245] 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 expansion valve (50) and then converted into a two-phase refrigerant, and then flows into the phase separator (61).

[0246] Inside the phase separator (61), the liquid refrigerant among the two-phase refrigerants is accumulated toward the bottom of the phase separator (61) by gravity, and the gaseous refrigerant is separated toward the top. The gaseous refrigerant separated toward the top bypasses the one or more shell-and-tube heat exchangers (71, 72, 73) (shell-tube evaporator) and is combined toward the discharge side, and the liquid refrigerant accumulated at the bottom of the phase separator (61) passes through the inlet valves (711, 721, 731) of the one or more open shell-and-tube heat exchangers (71, 72, 73), absorbs heat from cold water in each of the one or more shell-and-tube heat exchangers (71, 72, 73), and is then discharged as a gas.

[0247] By inducing the dryness of the refrigerant flowing into the one or more shell-and-tube heat exchangers (71, 72, 73) corresponding to the evaporator while passing through the phase separator (61) after expansion in the above expansion valve (50) before flowing 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, and by bypassing the gaseous refrigerant as much as the dryness before flowing into the evaporator to the evaporator outlet, thereby minimizing the refrigerant pressure loss due to the flowing gas within the evaporator, the cooling capacity can be improved (③ of FIG. 10).

[0248] After this, all low-temperature, low-pressure gaseous refrigerants that have passed through one or more shell-and-tube heat exchangers (71, 72, 73) are introduced into the first stage inlet of each of the first compressor (11) and the second compressor (12).

[0249] <Condition 3>

[0250] 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.

[0251] The above air conditioning system (100) can be operated as shown in Fig. 11 to circulate the refrigerant when the operation corresponds to heating operation and the temperature state is 0 [℃] or higher.

[0252] The above four-way valve (20) can switch the flow path so that the second stage discharge port of one compressor (11) with a larger capacity among the plurality of turbo compressors (11, 12) is connected to the inlet port of one or more outdoor heat exchangers (31, 32, 33), and the first stage inlet port of one compressor (11) is connected to the first stage inlet port of the other compressor (12).

[0253] The above plurality of turbo compressors (11, 12) can compress refrigerant in the first and second stages in sequence with the first compressor (11) and the other compressor (12) not driven, so that the refrigerant compressed in the second stage at the second stage discharge port of the first compressor (11) can be delivered to the one or more outdoor heat exchangers (31, 32, 33).

[0254] Accordingly, the plurality of turbo compressors (11, 12) can compress the refrigerant by driving only the first compressor (11).

[0255] Each of the above one or more outdoor heat exchangers (31, 32, 33) and the above one or more shell-and-tube heat exchangers (71, 72, 73) is configured in plurality, and one inlet valve (311, 711) is not opened, and the remaining inlet valves (321, 331, 721, 731) are opened, so that heat exchange can take place in each of the open heat exchangers (32, 33, 72, 73).

[0256] That is, heat exchange may not occur in one outdoor heat exchanger (31) and one shell-and-tube heat exchanger (71), but may occur in the remaining outdoor heat exchangers (32, 33) and the remaining shell-and-tube heat exchangers (72, 73).

[0257] 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.

[0258] 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 compressor (11).

[0259] 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 the first compressor (11).

[0260] 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), which is not operated, 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).

[0261] 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.

[0262] Meanwhile, in such a case, the inlet valve (421) of the second indoor heat exchanger (42) may be driven to close.

[0263] The specific operation of the air conditioning system (100) in this case and the results thereof are described below with reference to FIG. 12.

[0264] 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 first temperature- and pressure-increased gaseous refrigerant 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 final high-temperature and high-pressure gaseous refrigerant that is pressurized is discharged through the second compression process.

[0265] The inlet valves (321, 331) of some (66%) of the above one or more outdoor heat exchangers (31, 32, 33) are opened, and all of the high-temperature, high-pressure gaseous refrigerant is converted into medium-temperature, high-pressure liquid refrigerant and discharged after radiating heat to the outdoor air side from each of the outdoor heat exchangers (32, 33) (66%).

[0266] 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.

[0267] 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, performance degradation due to excessive refrigerant bypass can be minimized.

[0268] 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 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).

[0269] 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 expansion valve (50) and then converted into a two-phase refrigerant, and then flows into the phase separator (61).

[0270] Inside the above phase separator (61), the liquid refrigerant among the two-phase refrigerants is accumulated to the lower part of the phase separator (61) by gravity, and the gaseous refrigerant is separated to the upper part, and the gaseous refrigerant separated to the upper part bypasses the one or more shell-and-tube heat exchangers (71, 72, 73) (shell-tube evaporator) and is combined toward the discharge side, and the liquid refrigerant accumulated at the lower part of the phase separator (61) passes through the inlet valves (721, 731) of some of the open shell-and-tube heat exchangers (71, 72, 73) and absorbs heat from cold water in each of the heat exchangers (72, 73) and is then vaporized and discharged.

[0271] By inducing the dryness of the refrigerant flowing into the one or more shell-and-tube heat exchangers (71, 72, 73) corresponding to the evaporator while passing through the phase separator (61) after expansion in the expansion valve (50) before flowing 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, and by bypassing the gaseous refrigerant in an amount equal to the dryness before flowing into the evaporator to the evaporator outlet as much as possible, the refrigerant pressure loss due to the flowing gas within the evaporator can be minimized, thereby improving the cooling capacity (ⓛ in FIG. 12).

[0272] After this, all low-temperature, low-pressure gaseous refrigerant that has passed through the above-mentioned heat exchangers (72, 73) is introduced into the first stage inlet of the first compressor (11).

[0273] <Condition 4>

[0274] 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.

[0275] The above air conditioning system (100) can be operated as shown in Fig. 13 to circulate the refrigerant when the operation corresponds to heating operation and the temperature state is less than 0 [℃].

[0276] The above four-way valve (20) can switch the flow path so that the first stage inlet of a compressor (11) with a large capacity among the plurality of turbo compressors (11, 12) is connected to the first stage inlet of the other compressor (12).

[0277] The above plurality of turbo compressors (11, 12) can compress refrigerant in the first and second stages sequentially while the first compressor (11) is not operating, and transfer the refrigerant compressed in the second stage from the second stage discharge port of the other compressor (12) to the one or more outdoor heat exchangers (31, 32, 33).

[0278] Accordingly, the plurality of turbo compressors (11, 12) can compress the refrigerant by driving only the second compressor (12) having a smaller capacity than the first compressor (11).

[0279] Each of the above one or more outdoor heat exchangers (31, 32, 33) and the above one or more shell-and-tube heat exchangers (71, 72, 73) is configured in plurality, and one inlet valve (331, 731) is opened, and the remaining inlet valves (311, 321, 711, 721) are not opened, so that heat exchange can take place in the open heat exchangers (33, 73).

[0280] That is, heat exchange may occur in one outdoor heat exchanger (33) and one shell-and-tube heat exchanger (73), and heat exchange may not occur in the remaining outdoor heat exchangers (31, 32) and the remaining shell-and-tube heat exchangers (71, 72).

[0281] The above-described plurality of indoor heat exchangers (41, 42, 43) can be arranged adjacent to one or more of the outdoor heat exchangers (31, 32, 33) by opening the inlet valve (411) of the one heat exchanger (41), so that heat exchange can take place in the one heat exchanger (41).

[0282] That is, 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 passage of each of the plurality of turbo compressors (11, 12), thereby cooling the motor of each of the plurality of turbo compressors (11, 12) and supplying a portion of the refrigerant to the gas bearing.

[0283] At this time, the solenoid valves (111, 121) of each of the first compressor (11) and the second compressor (12) can be operated in a closed state.

[0284] Meanwhile, in such a case, the inlet valves (421, 431) of each of the second indoor heat exchanger (42) and the third indoor heat exchanger (43) may be driven to close.

[0285] The specific operation of the air conditioning system (100) in this case and the results thereof are described below with reference to FIG. 14.

[0286] Low-temperature and low-pressure gaseous refrigerant is introduced into the first stage inlet of the second compressor (12), and after the first compression, the first temperature- and pressure-increased gaseous refrigerant is discharged, and then introduced into the second stage inlet through the communication pipe, and through the second compression process, the final pressure-increased high-temperature and high-pressure gaseous refrigerant is discharged.

[0287] The inlet valves (331) of some (33 [%]) of the above one or more outdoor heat exchangers (31, 32, 33) are opened, and all of the high-temperature, high-pressure gaseous refrigerant is converted into medium-temperature, high-pressure liquid refrigerant after being radiated to the outdoor air side from some (33 [%]) of the outdoor heat exchangers (33) and discharged.

[0288] 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 motor of the second compressor (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.

[0289] 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, performance degradation due to excessive refrigerant bypass can be minimized.

[0290] 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 expansion valve (50) and then converted into a two-phase refrigerant, and then introduced into the phase separator (61).

[0291] Inside the above phase separator (61), the liquid refrigerant among the two-phase refrigerants is stacked toward the bottom of the phase separator (61) by gravity, and the gaseous refrigerant is separated toward the top. The gaseous refrigerant separated toward the top bypasses the one or more shell-and-tube heat exchangers (71, 72, 73) (shell-tube evaporator) and is combined toward the discharge side. The liquid refrigerant stacked at the bottom of the phase separator (61) passes through the inlet valve (731) of some of the open shell-and-tube heat exchangers (71, 72, 73) and absorbs heat from cold water in each of the heat exchangers (73) and then becomes gaseous and is discharged.

[0292] By inducing the dryness of the refrigerant flowing into the one or more shell-and-tube heat exchangers (71, 72, 73) corresponding to the evaporator while passing through the phase separator (61) after expansion in the expansion valve (50) before flowing 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 in an amount equal to the dryness before flowing into the evaporator to the evaporator outlet as much as possible, the refrigerant pressure loss due to the flowing gas within the evaporator can be minimized, thereby improving the cooling capacity (ⓛ in FIG. 14).

[0293] After this, all low-temperature, low-pressure gaseous refrigerant that has passed through the above-mentioned heat exchanger (73) is introduced into the first stage inlet of the second compressor (12).

[0294] 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 four-way valve for switching the flow path of refrigerant flowing into or discharged from the plurality of turbo compressors; One or more outdoor heat exchangers in which heat exchange of refrigerant delivered from one or more of the above plurality of turbo compressors is performed; A plurality of internal heat exchangers in which heat exchange of refrigerant delivered from one or more outdoor heat exchangers is performed; An expansion valve in which expansion of the refrigerant delivered from the plurality of internal heat exchangers occurs; A phase separator that separates the phase of the refrigerant delivered from the expansion valve and delivers the separated gaseous refrigerant to the plurality of turbo compressors; and One or more shell-and-tube heat exchangers that perform heat exchange of the liquid refrigerant transferred from the above-mentioned phase separator and transfer the heat-exchanged refrigerant to the plurality of turbo compressors. Including, The above plurality of turbo compressors and the four-way valve, An air conditioning system characterized in that the refrigerant circulates differently depending on the operating conditions, such as whether the system is in cooling / heating operation and the outdoor temperature condition.

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 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 A fourth valve connected to the inlet of one or more of the outdoor heat exchangers 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, If the above one or more outdoor heat exchangers are composed of multiples, It comprises a first outdoor heat exchanger, a second outdoor heat exchanger and a third outdoor heat exchanger arranged in parallel, Each of the first outdoor heat exchanger to the third outdoor heat exchanger, Including an inlet valve that opens and closes the inlet, An air conditioning system characterized in that refrigerant delivered from at least one of the plurality of turbocompressors undergoes heat exchange in at least one outdoor heat exchanger according to the operation of the above inlet valve.

5. In paragraph 1, At least one of the above multiple indoor heat exchangers, An air conditioning system characterized in that at least a portion of the heat-exchanged refrigerant is transferred to one or more of the plurality of turbocompressors.

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, 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 including:

8. In paragraph 1, If the above one or more shell and tube heat exchangers are composed of multiples, It comprises a first shell-and-tube heat exchanger, a second shell-and-tube heat exchanger and a third shell-and-tube heat exchanger arranged in parallel, Each of the first shell-and-tube heat exchanger to the third shell-and-tube heat exchanger, Including an inlet valve that opens and closes the inlet, An air conditioning system characterized in that the refrigerant delivered from the phase separator undergoes heat exchange in one or more shell-and-tube heat exchangers according to the operation of the inlet valve.

9. In paragraph 1, If the above driving status corresponds to cooling driving and the above temperature condition is 27 [℃] or higher, The above 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 one or more outdoor heat exchangers is connected to the discharge port of one or more shell-and-tube heat exchangers. 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 one or more outdoor heat exchangers.

10. In paragraph 9, If the above driving status corresponds to cooling driving and the above temperature condition is 27 [℃] or higher, Each of the one or more outdoor heat exchangers and the one or more shell-and-tube heat exchangers, An air conditioning system characterized in that each inlet valve is opened and heat exchange occurs in each.

11. In paragraph 9, If the above driving status corresponds to cooling driving 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 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 status corresponds to cooling driving and the temperature condition is below 27 [℃], The above four-way valve, The flow path is switched so that the second stage discharge port of one compressor among the plurality of turbo compressors is connected to the inlet port of the one or more outdoor heat exchangers, and the first stage inlet port of the one compressor is connected to the first stage inlet port of the other compressor. 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 one or more outdoor heat exchangers.

13. In paragraph 12, If the above driving status corresponds to cooling driving and the temperature condition is below 27 [℃], Each of the one or more outdoor heat exchangers and the one or more shell-and-tube heat exchangers, An air conditioning system characterized in that each inlet valve is opened and heat exchange occurs in each.

14. In paragraph 12, If the above driving status corresponds to cooling driving and the temperature condition is below 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, placed before the 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 status corresponds to heating driving and the above temperature status is 0 [℃] or higher, The above four-way valve, The second stage discharge port of one compressor having a larger capacity among the plurality of turbo compressors is connected to the inlet port of one or more outdoor heat exchangers, and the flow path is changed so that the first stage inlet port of the one compressor is connected to the first stage inlet port of the other compressor. The above plurality of turbo compressors, An air conditioning system characterized in that the above compressor compresses the refrigerant in the first and second stages in sequence, and the other compressor is not driven, so that the refrigerant compressed in the second stage is delivered from the second stage discharge port of the above one compressor to the one or more outdoor heat exchangers.

16. In paragraph 15, If the above driving status corresponds to heating driving and the above temperature status is 0 [℃] or higher, Each of the above one or more outdoor heat exchangers and the above one or more shell-and-tube heat exchangers is composed of multiples, An air conditioning system characterized in that one inlet valve is not opened and the remaining inlet valves are opened, and heat exchange is performed in each of the open heat exchangers.

17. In paragraph 16, If the above driving status corresponds to heating driving and the above temperature status is 0 [℃] or higher, 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, placed before the 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 status corresponds to heating driving and the above temperature status is below 0 [℃], The above four-way valve, The flow path is changed so that the first stage inlet of a compressor with a large capacity among the above multiple turbo compressors is connected to the first stage inlet of the other compressor, The above plurality of turbo compressors, An air conditioning system characterized in that the above compressor is not operating, the other compressor compresses the refrigerant in the first and second stages in sequence, and the refrigerant compressed in the second stage is delivered to the one or more outdoor heat exchangers from the second stage discharge port of the other compressor.

19. In paragraph 18, If the above driving status corresponds to heating driving and the above temperature status is below 0 [℃], Each of the above one or more outdoor heat exchangers and the above one or more shell-and-tube heat exchangers is composed of multiples, An air conditioning system characterized in that one inlet valve is opened and the remaining inlet valves are not opened, and heat exchange is performed in each of the open heat exchangers.

20. In paragraph 18, If the above driving status corresponds to heating driving and the above temperature status is below 0 [℃], The above multiple indoor heat exchangers are, An air conditioning system characterized in that the inlet valve of a heat exchanger positioned adjacent to one or more outdoor heat exchangers is opened, so that heat exchange occurs in the heat exchanger.

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