US20100275624A1 - Air-Conditioning System And Controlling Method For The Same - Google Patents

Abstract

An air-conditioning system and a controlling method for the same that is capable of improving the operational efficiency of the air-conditioning system are disclosed. The air-conditioning system includes a phase separator (500) for separating a flowing refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant, an evaporator (600) for evaporating the liquid-phase refrigerant separated by the phase separator (500), a compressor (100) having a first compression part into which the refrigerant having passed through the evaporator (600) is introduced and a second compression part into which both the gas-phase refrigerant separated by the phase separator (500) and the refrigerant having passed through the first compression part are introduced, and a control unit for simultaneously or selectively controlling the amount of the refrigerant introduced into the phase separator (500) and the amount of the refrigerant discharged from the phase separator (500).

Description

TECHNICAL FIELD
• The present invention relates to an air-conditioning system, and more particularly, to an air-conditioning system and a controlling method for the same that is capable of improving the operational efficiency of the air-conditioning system.
BACKGROUND ART
• Generally, an air-conditioning system is a system that compresses, condenses, expands, and evaporates a refrigerant to cool and/or heat the interior of a room.
• The air-conditioning system may be classified as a normal air-conditioning system constructed in a structure in which a single indoor unit is connected to an outdoor unit and a multi air-conditioning system constructed in a structure in which a plurality of indoor units are connected to an outdoor unit. Also, the air-conditioning system may be classified as a cooling system constructed in a structure in which a refrigerant cycle is operated only in one direction to supply cool air into the interior of a room and a cooling and heating system constructed in a structure in which a refrigerant cycle is selectively operated in opposite directions to supply cool air or warm air into the interior of a room.
• The construction of a conventional separation type air-conditioning system will be described in brief with reference toFIG. 1.
• The conventional air-conditioning system fundamentally forms a refrigeration cycle including compressors1aand1b, acondenser3, an expansion valve4, and an evaporator5. These components are connected to each other via aconnection pipe7 serving as a flow channel through which a refrigerant flows.
• The operation of the air-conditioning system to cool the interior of a room will be described below based on the flow of the refrigerant.
• A gas-phase refrigerant heat-exchanged with indoor air in the evaporator5 is introduced into the compressors1aand1b. The gas-phase refrigerant introduced into the compressors1aand1bare compressed into high temperature and high pressure by the compressors1aand1b. After that, the gas-phase refrigerant is introduced into thecondenser3 where the gas-phase refrigerant is phase-changed into a liquid-phase refrigerant. As the refrigerant is phase-changed in thecondenser3, heat is emitted from thecondenser3.
• Subsequently, the refrigerant is discharged from the condenser, passes through the expansion valve4 where the refrigerant is expanded, and is introduced into the evaporator5. The liquid-phase refrigerant introduced into the evaporator5 is phase-changed into a gas-phase refrigerant. As the refrigerant is phase-changed in the evaporator5, the refrigerant absorbs external heat, thereby cooling the interior of the room. Of course, the refrigeration cycle may be operated in the opposite direction to heat the interior of the room.
• On the other hand, an accumulator6 is mounted between the evaporator5 and the compressors1aand1b. A mixture of oil and refrigerant is temporarily stored in the accumulator6. Also, the accumulator6 serves to prevent the backward-flow of the refrigerant and the introduction of the liquid-phase refrigerant into the compressors1aand1b.
• The compressors1aand1binclude a first compressor1aand a second compressor1bindividually connected to the accumulator6. The first and second compressors1aand1bhave the different capacities. Constant-speed compressors, which are operated at a constant operating speed, are used as the first and second compressors1aand1b. Consequently, one corresponding compressor is operated according to load required in the air-conditioning system. Before the refrigerant is introduced into the first compressor1a, the flow of the refrigerant is controlled by afirst check valve2a. Before the refrigerant is introduced into the second compressor1b, the flow of the refrigerant is controlled by means of asecond check valve2b.
DISCLOSURE OF INVENTIONTechnical Problem
• In the conventional air-conditioning system, however, uniform compression work is supplied to the compressors even when the required load is changed with the result that electric power is unnecessarily consumed and the operational efficiency of the air-conditioning system is decreased.
• Also, the two compressors are individually mounted in the conventional air-conditioning system, and therefore, drive units for driving the two compressors are also mounted in the conventional air-conditioning system with the result that an installation space is restricted. Furthermore, the manufacturing costs of the air-conditioning system increase.
• In addition, the operating range of the conventional air-conditioning system is determined only by the capacities of the respective compressors with the result that the operating range is restricted.
• Furthermore, the liquid-phase refrigerant may be introduced into the compressors when the operation of the conventional air-conditioning system is initiated. When the liquid-phase refrigerant is introduced into the compressors, however, excessive load is applied to the compressors with the result that the reliability of the compressors abruptly is decreased.
Technical Solution
• An object of the present invention devised to solve the problem lies on an air-conditioning system and a controlling method for the same that is capable of improving the operational efficiency of the air-conditioning system.
• Another object of the present invention devised to solve the problem lies on an air-conditioning system and a controlling method for the same that is capable of reducing compression work applied to a compressor and preventing the introduction of a liquid-phase refrigerant into the compressor.
• Another object of the present invention devised to solve the problem lies on an air-conditioning system and a controlling method for the same that is capable of extending the operating range of the air-conditioning system.
• A further object of the present invention devised to solve the problem lies on an air-conditioning system and a controlling method for the same that is capable of easily performing the operation of the air-conditioning system and reducing the manufacturing costs of the air-conditioning system.
• The object of the present invention can be achieved by providing an air-conditioning system including a phase separator for separating a flowing refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant, an evaporator for evaporating the liquid-phase refrigerant separated by the phase separator, a compressor having a first compression part into which the refrigerant having passed through the evaporator is introduced and a second compression part into which both the gas-phase refrigerant separated by the phase separator and the refrigerant having passed through the first compression part are introduced, and a control unit for simultaneously or selectively controlling the amount of the refrigerant introduced into the phase separator and the amount of the refrigerant discharged from the phase separator.
• Preferably, the air-conditioning system further includes a first expansion valve for controlling the amount of the refrigerant introduced into the phase separator, a second expansion valve for controlling the amount of the liquid-phase refrigerant discharged from the phase separator and introduced into the evaporator, and a refrigerant control valve for controlling the amount of the gas-phase refrigerant discharged from the phase separator and introduced into the second compression part.
• Preferably, the control unit controls the amount of the gas-phase refrigerant introduced into the second compression part depending upon operation load of the system.
• Specifically, the control unit controls the opening amount of the refrigerant control valve based on a frequency of the compressor determined depending upon the operation load of the system.
• Preferably, the operation load of the system is determined depending upon factors including operation mode set by a user.
• Preferably, the operation load of the system is determined depending upon factors including outdoor temperature and indoor temperature.
• Preferably, the air-conditioning system further includes a temperature sensor for measuring the outdoor temperature and the indoor temperature.
• Preferably, the air-conditioning system further includes a measuring sensor for measuring data related to the state of the refrigerant.
• Preferably, the measuring sensor is mounted on a first refrigerant pipe through which the gas-phase refrigerant separated by the phase separator flows.
• Preferably, the measuring sensor is a temperature sensor for measuring the temperature of the gas-phase refrigerant.
• Preferably, the measuring sensor is a pressure sensor mounted in at least one of a first refrigerant pipe, a second refrigerant pipe, and a mixed refrigerant pipe connected to the phase separator.
• Preferably, the control unit converts the pressure data measured by the pressure sensor into temperature data corresponding to the pressure data.
• Preferably, the control unit controls the valves based on data related to the state of the refrigerant set depending upon the outdoor temperature and the data measured by the measuring sensor.
• Preferably, the measuring sensor includes a pressure sensor and/or a temperature sensor, and the measuring sensor is mounted at an outlet port of the compressor.
• Preferably, the control unit closes all the valves to prevent the introduction of the liquid-phase refrigerant into the compressor when the operation of the air-conditioning system is initiated.
• In another aspect of the present invention, provided herein is a controlling method for an air-conditioning system including detecting data necessary for the operation of the system, and simultaneously or selectively controlling the amount of refrigerant introduced into a phase separator and the amount of refrigerant discharged from the phase separator based on the detected data.
• Preferably, the data includes operation load of the system, and the controlling method further includes determining an operation frequency of a compressor corresponding to the operation load of the system, and operating the compressor at the determined operation frequency.
• Preferably, the step of controlling the amount of refrigerant includes setting the opening amount of a refrigerant control valve depending upon the operation frequency of the compressor, and controlling the refrigerant control valve depending upon the set opening amount.
• Preferably, the controlling method further includes changing operation mode of the air-conditioning system, and resetting the opening amount of the refrigerant control valve depending upon the changed operation mode of the air-conditioning system.
• Preferably, the data includes data related to the state of the refrigerant, and the controlling method further includes comparing the measured data with data related to the state of the refrigerant previously set depending upon outdoor temperature, and controlling valves mounted on refrigerant pipes connected to the phase separator based on the measured data and the set data.
• Preferably, the data includes the temperature of the refrigerant, and the step of controlling the valves includes, when the temperature of the refrigerant does not exceed a first predetermined temperature previously stored in the control unit, closing a refrigerant control valve through which a gas-phase refrigerant is discharged from the phase separator, and opening a first expansion valve through which the refrigerant is introduced into the phase separator and a second expansion valve through which a liquid-phase refrigerant is discharged from the phase separator and introduced into an evaporator by predetermined opening degrees, respectively.
• Preferably, the step of controlling the valves includes, when the temperature of the refrigerant exceeds a second predetermined temperature previously stored in the control unit, resetting the opening degrees of the refrigerant control valve, the first expansion valve, and the second expansion valve to be the opening degrees just before the valves are controlled.
• Preferably, the step of controlling the amount of refrigerant includes controlling a first expansion valve mounted on a mixed refrigerant pipe through which the refrigerant is introduced into the phase separator, controlling a refrigerant control valve mounted on a first refrigerant pipe through which a gas-phase refrigerant separated by the phase separator flows, and controlling a second expansion valve mounted on a second refrigerant pipe through which a liquid-phase refrigerant separated by the phase separator flows to an evaporator.
• Preferably, all the valves are closed to prevent the introduction of the liquid-phase refrigerant into the compressor when the operation of the air-conditioning system is initiated.
• Preferably, the first expansion valve and the second expansion valve are opened to predetermined opening degrees, respectively, until the measured data is within a range of reference data of the stabilized system after all the valves are closed.
• Preferably, when the measured data is within the range of reference data, the refrigerant control valve is opened to a predetermined opening degree.
• Preferably, after the refrigerant control valve is opened to the predetermined opening degree, the opening degrees of the first expansion valve, the second expansion valve, and the refrigerant control valve are controlled depending upon outdoor temperature.
ADVANTAGEOUS EFFECTS
• The air-conditioning system according to the present invention and the controlling method for the same have the following effects.
• First, the opening amount of the refrigerant control valve is controlled depending upon the operation load of the air-conditioning system. Consequently, the air-conditioning system is efficiently operated. Specifically, in an air-conditioning system constructed in a structure in which a first compression part and a second compression part having variable capacities are mounted in a single compressor, a gas-phase refrigerant is optimally supplied to the second compression part depending upon the operation load of the air-conditioning system. Consequently, the air-conditioning system is efficiently operated.
• Especially, the operation frequency of the compressor is determined depending upon the operation load of the air-conditioning system, and the opening amount of the refrigerant control valve is controlled depending upon the operation frequency of the compressor. Consequently, it is possible to reduce the compression work, and, at the same time, accomplishing the maximum heating and cooling efficiencies.
• Second, the gas-phase refrigerant separated by the phase separator is supplied to the second compression part. Consequently, the compression work applied to the compressor is reduced. Furthermore, the structure of the phase separator is improved to prevent the introduction of the liquid-phase refrigerant into the compressor. Consequently, the reliability of the compressor is increased.
• Third, the valves are controlled, when the operation of the air-conditioning system is initiated or abrupt change of the pressure occurs, to prevent the introduction of the liquid-phase refrigerant into the compressor from the phase separator. Consequently, the breakdown of the compressor is prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
• The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention.
• In the drawings:
• FIG. 1 is a view schematically illustrating the construction of a conventional air-conditioning system.
• FIG. 2 is a view schematically illustrating the construction of an air-conditioning system according to the present invention.
• FIG. 3 is a graph illustrating a refrigeration cycle of the air-conditioning system shown inFIG. 2.
• FIG. 4 is a longitudinal sectional view schematically illustrating a compressor mounted in the air-conditioning system shown inFIG. 2.
• FIG. 5 is a longitudinal sectional view schematically illustrating a phase separator mounted in the air-conditioning system shown inFIG. 2.
• FIG. 6 is a graph illustrating the operation of the compressor in the air-conditioning system shown inFIG. 2 depending upon external load.
• FIG. 7 is a graph illustrating the operational efficiency of compressor shown inFIG. 4.
• FIG. 8 is a block diagram illustrating a process for controlling the air-conditioning system shown inFIG. 2.
• FIG. 9 is a flow chart illustrating an embodiment of controlling method for an air-conditioning system according to the present invention.
• FIG. 10 is a graph illustrating the performance of the air-conditioning system depending upon the opening degree of a refrigerant control pipe provided at the air-conditioning system according to the present invention.
• FIG. 11 is a flow chart illustrating another embodiment of controlling method for an air-conditioning system according to the present invention.
• FIG. 12 is a flow chart illustrating a further embodiment of controlling method for an air-conditioning system according to the present invention.
MODE FOR THE INVENTION
• Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
• First, the construction of an air-conditioning system according to the present invention will be described in detail with reference toFIG. 2.
• The air-conditioning system includes anevaporator600, acondenser300,expansion valves410 and420, acompressor100, and aphase separator500 for separating a refrigerant introduced therein into a gas-phase refrigerant and a liquid-phase refrigerant. In addition, the air-conditioning system further includes a four-way valve200 for controlling the flow of the refrigerant supplied to thecondenser300, thecompressor100, and theevaporator600. Hereinafter, the air-conditioning system will be described based on the flow of the refrigerant when the cooling operation is performed to cool the interior of a room.
• Specifically, afirst compression part110 includes a first cylinder111 (seeFIG. 4) into which the refrigerant having passed through theevaporator600 is introduced, and asecond compression part120 includes a second cylinder121 (seeFIG. 4) having a volume different than that of thefirst cylinder111.
• Between thephase separator500 and thecompressor100 is mounted a refrigerant introduction unit for guiding the refrigerant to thefirst compression part110 and thesecond compression part120.
• The refrigerant introduction unit may include anintermediate refrigerant pipe740 connected between thefirst compression part110 and thesecond compression part120, a firstrefrigerant pipe710 connected between the intermediaterefrigerant pipe740 and thephase separator500, and a secondrefrigerant pipe720 connected between thefirst compression part110 and thephase separator500. Also, the refrigerant introduction unit may include arefrigerant control valve730 mounted on the firstrefrigerant pipe710 for controlling the flow of a gas-phase refrigerant introduced into thesecond compression part120.
• Theexpansion valves410 and420 includes afirst expansion valve410 for primarily expanding the refrigerant having passed through thecondenser300 and asecond expansion valve420 for expanding a liquid-phase refrigerant separated by thephase separator500. The refrigerant having passed through thecondenser300 is excessively cooled. As the refrigerant passes through thefirst expansion valve410, the refrigerant expands and is introduced into thephase separator500 while a gas-phase refrigerant and a liquid-phase refrigerant are mixed with each other.
• Thephase separator500 is mounted between thefirst expansion valve410 and thesecond expansion valve420 for separating the gas-phase refrigerant and the liquid-phase refrigerant from each other. Thephase separator500 is connected to a mixedrefrigerant pipe750 through which the refrigerant having passed through thecondenser300 flows. Also, thephase separator500 is connected to the firstrefrigerant pipe710 through which the gas-phase refrigerant separated by thephase separator500 flows and to the secondrefrigerant pipe720 through which the liquid-phase refrigerant separated by thephase separator500 flows.
• As the liquid-phase refrigerant separated by thephase separator500 passes through thesecond expansion valve420, the liquid-phase refrigerant expands. The liquid-phase refrigerant having passed through thesecond expansion valve420 is introduced into theevaporator600 where the liquid-phase refrigerant is phased-changed into a gas-phase refrigerant. After that, the gas-phase refrigerant having passed through theevaporator600 is introduced into the compressor, i.e., thefirst compression part110, through the four-way valve200.
• The gas-phase refrigerant separated by thephase separator500 flows through the firstrefrigerant pipe710 and is mixed with the refrigerant having passed through thefirst compression part110 in the intermediaterefrigerant pipe740. The refrigerants mixed in the intermediaterefrigerant pipe740 are introduced into thesecond compression part120 where the refrigerants are compressed. The compressed refrigerants are discharged out of the compressor.
• Thephase separator500 is not particularly restricted so long as thephase separator500 can separate the gas-phase refrigerant from the refrigerant having passed through the condenser. For example, thephase separator500 may include a heat exchanger, by which heat exchange between the refrigerant having passed through the condenser and external air is performed to obtain a gas-phase refrigerant from the refrigerant.
• Therefrigerant control valve730 is controlled by a control unit (not shown) for controlling the operation of the air-conditioning system. The control unit serves to drive thefirst compression part110 and thesecond compression part120. Also, the control unit serves to control therefrigerant control valve730.
• On the firstrefrigerant pipe710 may be mounted a capillary tube for controlling the flow rate of the gas-phase refrigerant introduced into the intermediaterefrigerant pipe740. Specifically, it is possible to control the amount of the gas-phase refrigerant introduced into the intermediaterefrigerant pipe740 by controlling the inner diameter of the firstrefrigerant pipe710.
• Since both the gas-phase refrigerant separated by thephase separator500 and the refrigerant compressed by thefirst compression part110 are compressed in thesecond compression part120, compression work applied to thecompressor100 is decreased. As the compression work of thecompressor100 is decreased, the operating range of thecompressor100 is extended with the result that the air-conditioning system may be used even in severely cold regions or tropical regions.
• The present invention is not limited to the above-described embodiment. When the operation of the air-conditioning system is initiated or the reliability of the air-conditioning system is confirmed, for example, the refrigerant control valve may be closed to prevent the introduction of the gas-phase refrigerant into the second compression part.
• Also, the air-conditioning system may be constructed such that the compressor is operated while the refrigerant control valve is closed even in a region where external load is low. When the external load is within a predetermined load range, for example, the control unit closes therefrigerant control valve730 so as to drive only the first compression part. As a result, the gas-phase refrigerant separated by thephase separator500 is not introduced into thesecond compression part120 any more. Consequently, thephase separator500 serves as a receiver.
• Of course, it is possible to operate only the second compression part or both the first and second compression parts while the gas-phase refrigerant separated by the phase separator is not supplied into the intermediate refrigerant pipe, i.e., the refrigerant control valve is closed.
• Hereinafter, the pressure-enthalpy conversion of the air-conditioning system according to the present invention will be described with reference toFIGS. 2 and 3.
• In a general air-conditioning system, a refrigeration cycle includes acompressing process10→20a, a condensingprocess20a→30, an expandingprocess30→60a, and an evaporatingprocess60a→10. However, the refrigeration cycle of the air-conditioning system according to this embodiment includes acompressing process10→90→80→20, a condensingprocess20→30, an expandingprocess30→40→50→60, and an evaporatingprocess60→10.
• In this embodiment, the compressing process includes afirst compressing process10→90 and a second compressing process80→20. The first compressing process is a compressing process carried out in thefirst compression part110, and the second compressing process is a compressing process carried out in thesecond compression part120.
• The reason why the start point of the second compressing process is shifted from Point90 to Point80 is that the gas-phase refrigerant separated by thephase separator500 is introduced into thesecond compression part120 through the intermediaterefrigerant pipe740. That is, the gas-phase refrigerant separated by thephase separator500 is mixed with the refrigerant having passed through thefirst compression part110, and is then introduced into thesecond compression part120 to decrease the enthalpy of the entire refrigerant.
• Specifically, the gas-phase refrigerant separated by thephase separator500 is mixed with the refrigerant compressed by thefirst compression part110, and is then supplied to thesecond compression part120, whereby the compression work required in the compressor is reduced by W21, and therefore, the total energy efficiency of the air-conditioning system is increased.
• Also, in this embodiment, the expanding process includes a first expandingprocess30→40 and a second expandingprocess50→60. The first expanding process is an expanding process carried out in thefirst expansion valve410, and the second expanding process is an expanding process carried out in thesecond expansion valve420.
• The reason why the start point of the second expanding process is shifted fromPoint40 to Point50, i.e., work is gained by W11, is that only the gas-phase refrigerant is separated from the refrigerant introduced into thephase separator500, and then flows through the firstrefrigerant pipe710. That is, the gas-phase refrigerant is discharged from the phase separator, whereby the enthalpy of the refrigerant introduced into the evaporator is reduced. As a result, the heat exchange efficiency of theevaporator600 is increased, and therefore, the cooling efficiency of the air-conditioning system is improved.
• Also, the gas-phase refrigerant separated by thephase separator500 as well as the refrigerant having passed through theevaporator600 is supplied into thecompressor100. Consequently, the circulating amount of the refrigerant is increased with the result that the capacity of thecompressor100 is increased, and therefore, the efficiency of the air-conditioning system is greatly improved.
• The present invention is not limited to the above-described embodiment. For example, a heat exchanger may be mounted between the first refrigerant pipe and the second refrigerant pipe for performing heat exchange between the gas-phase refrigerant separated by thephase separator500 and the refrigerant having passed through theevaporator600, whereby the enthalpy of the refrigerant introduced into the compressor is further decreased. As a result, the compression work required in the compressor is further reduced.
• Hereinafter, the compressor according to the present invention and the refrigerant introduction unit for guiding the refrigerant to the compressor will be described with reference toFIG. 4.
• The compressor includes acase130 forming the appearance of the compressor, adrive unit140 mounted in thecase130, and afirst compression part110 and asecond compression part120 driven by thedrive unit140.
• Thedrive unit140 includes astator141 having a winding coil and arotor143 rotatably mounted in thestator141. Arotary shaft145 is fitted in therotor143. Therotary shaft145 is connected to thefirst compression part110 and thesecond compression part120.
• Thefirst compression part110 and thesecond compression part120 have compression capacities variable depending upon external load. Thefirst compression part110 and thesecond compression part120 are mounted in a single compressor. Thefirst compression part110 is mounted in the lower end of thecase130, and thesecond compression part120 is mounted above thefirst compression part110. Of course, an intermediate plate may be mounted between thefirst compression part110 and thesecond compression part120 for separating thefirst compression part110 and thesecond compression part120 from each other.
• Thefirst compression part110 includes afirst cylinder111 having a refrigerant compression space defined therein and afirst bearing113 mounted at the bottom of thefirst cylinder111. Thesecond compression part120 includes asecond cylinder121 having a refrigerant compression space defined therein and asecond bearing123 mounted at the top of thesecond cylinder111. Of course, thefirst bearing113 may be mounted at the top of thefirst cylinder111, andsecond bearing123 may be mounted at the bottom of thesecond cylinder111.
• Thefirst cylinder111 is provided at one side thereof with a firstcylinder inlet port111athrough which the refrigerant, having passed through the evaporator, is introduced into thefirst cylinder111. Thefirst cylinder111 is provided at the other side thereof with a firstcylinder outlet port111bthrough which the refrigerant compressed in thefirst cylinder111 is discharged. Of course, a first opening and closing valve may be mounted in the firstcylinder outlet port111bfor opening and closing the firstcylinder outlet port111b.
• Thesecond cylinder121 is provided at one side thereof with a secondcylinder inlet port121athrough which the refrigerant compressed by thefirst compression part110 and the gas-phase refrigerant separated by the phase separator are introduced into thesecond cylinder121. Thesecond cylinder121 is provided at the other side thereof with a secondcylinder outlet port121bthrough which the refrigerant compressed in thesecond cylinder121 is discharged. Also, a second opening and closing,valve125 is mounted in the secondcylinder outlet port121bfor opening and closing the secondcylinder outlet port121b.
• Of course, a multi-stage compressor, including three or more compression units, may be used as the compressor. Specifically, it is possible to provide one or more compression units which use the gas-phase refrigerant separated by the phase separator.
• On the other hand, the refrigerant introduced into the first compression part and the second compression part is controlled by the refrigerant introduction unit. Therefrigerant control valve730 is mounted on the firstrefrigerant pipe710 for controlling the flow of the gas-phase refrigerant flowing through the firstrefrigerant pipe710. The firstrefrigerant pipe710 is connected to the intermediaterefrigerant pipe740. The intermediaterefrigerant pipe740 communicates with the secondcylinder outlet port121b. Also, the intermediaterefrigerant pipe740 communicates with the firstcylinder outlet port111b. Consequently, the refrigerant compressed in the first cylinder and the gas-phase refrigerant separated by the phase separator are introduced into thesecond cylinder121 where the refrigerants are compressed.
• Of course, the refrigerant compressed in the first cylinder and the gas-phase refrigerant separated by the phase separator may be introduced individually into thesecond cylinder121. Specifically, the intermediaterefrigerant pipe740 may directly communicate with thesecond cylinder121, and the firstcylinder outlet port111bmay directly communicate with thesecond cylinder121, whereby the refrigerants are individually introduced into thesecond cylinder121.
• Hereinafter, the operation of the air-conditioning system using the compressor with the above-stated construction will be described.
• When the operation of the air-conditioning system is initiated, thecompressor100 having thefirst compression part110 and thesecond compression part120, thecondenser300, thephase separator500, theexpansion valves410 and420, and theevaporator600 are driven.
• First, thephase separator500 separates the refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant.
• The liquid-phase refrigerant separated by thephase separator500 is introduced into theevaporator600, and the gas-phase refrigerant separated by thephase separator500 is introduced into the intermediaterefrigerant pipe740 connected to thecompressor100. The control unit simultaneously drives thefirst compression part110 and thesecond compression part120 and opens therefrigerant control valve730 such that the gas-phase refrigerant separated by thephase separator500 is introduced into the intermediaterefrigerant pipe740.
• The liquid-phase refrigerant introduced into theevaporator600 is phase-changed into a gas-phase refrigerant while the liquid-phase refrigerant passes through theevaporator600. The gas-phase refrigerant is expanded while the gas-phase refrigerant passes through thesecond expansion valve420. The gas-phase refrigerant having passed through thesecond expansion valve420 is introduced into thefirst compression part110 of thecompressor100.
• The refrigerant compressed in thefirst compression part110 is introduced into the intermediaterefrigerant pipe740. The refrigerants mixed in the intermediaterefrigerant pipe740 are introduced into thesecond compression part120 of thecompressor100 where the refrigerants are compressed.
• Specifically, the refrigerant having passed through the evaporator is introduced into thefirst cylinder111 through the firstcylinder inlet port111a, and is then compressed in thefirst cylinder111. The refrigerant compressed in thefirst cylinder111 is introduced into the intermediaterefrigerant pipe740 through the firstcylinder outlet port111b.
• As a result, the gas-phase refrigerant separated by thephase separator500 and the refrigerant compressed by thefirst compression part110 are mixed with each other in the intermediaterefrigerant pipe740. The mixed refrigerants are introduced into thesecond cylinder121 through the secondcylinder inlet port121a, and are then compressed in thesecond cylinder121. After that, the refrigerants are discharged out of thesecond cylinder121 through the secondcylinder outlet port121b, and are then introduced into the condenser through acompressor discharge pipe133 provided at thecase130.
• Thefirst cylinder111 and thesecond cylinder121 have different volumes. Also, thefirst cylinder111 and thesecond cylinder121 have different compressibilities. Specifically, on the assumption that the volume of thefirst cylinder111 is 100, the volume of thesecond cylinder121 is 40 to 80.
• Of course, the compressor may be operated while the gas-phase refrigerant is not introduced into the intermediate refrigerant pipe. Specifically, the refrigerant having passed through the phase separator is introduced into one side of the first compression part, i.e., the firstcylinder inlet port111a, through the evaporator, and is then compressed in thefirst cylinder111 by the operation of the drive unit.
• The compressed refrigerant is introduced into the intermediaterefrigerant pipe740 through the firstcylinder outlet port111b. The refrigerant introduced into the intermediaterefrigerant pipe740 is introduced into thesecond cylinder121. However, the refrigerant may be compressed or not in thesecond cylinder121. Whether to compress the refrigerant in thesecond cylinder121 may be determined depending upon a load range.
• Hereinafter, the structure of the phase separator according to the present invention will be described with reference toFIG. 5.
• The phase separator includes astorage container530 for storing a refrigerant, a mixed refrigerantpipe connection part550 for guiding the refrigerant to thestorage container530, aseparation plate540 mounted in thestorage container530, a first refrigerantpipe connection part510 through which a gas-phase refrigerant separated from the refrigerant stored in thestorage container530 is discharged out of thestorage container530, and a second refrigerantpipe connection part520 through which a liquid-phase refrigerant separated from the refrigerant stored in thestorage container530 is discharged out of thestorage container530.
• Thestorage container530 provides a space for temporarily storing the refrigerant. Specifically, a mixture of a gas-phase refrigerant and a liquid-phase refrigerant is introduced into thestorage container530.
• Thestorage container530 includes acylindrical container body531, atop wall533 formed at the upper end of thecontainer body531, and abottom wall535 formed at the lower end of thecontainer body531.
• The mixed refrigerantpipe connection part550 and the second refrigerantpipe connection part520 extend downward through thetop wall533 while the mixed refrigerantpipe connection part550 and the second refrigerantpipe connection part520 are spaced a predetermined distance from thebottom wall535.
• Theseparation plate540 serves to separate the refrigerant introduced into the storage container into a liquid-phase refrigerant and a gas-phase refrigerant. Theseparation plate540 is mounted below thetop wall533. Consequently, when the refrigerant is introduced into thestorage container530 through the mixed refrigerantpipe connection part550, the gas-phase refrigerant component of the refrigerant passes through theseparation plate540, and is then supplied to the compressor through the first refrigerantpipe connection part510.
• On the other hand, the liquid-phase refrigerant component of the refrigerant collides with theseparation plate540 with the result that the liquid-phase refrigerant component falls downward from theseparation plate540. After that, the liquid-phase refrigerant, stored in the storage container below theseparation plate540, is discharged through the second refrigerantpipe connection part520, and is then introduced into thesecond expansion valve420.
• When external load is large, i.e., in severely cold regions or tropical regions, the air-conditioning system has a refrigerant flow in which the gas-phase refrigerant separated by the phase separator is introduced into thesecond compression part120 while the gas-phase refrigerant separated by the phase separator is mixed with the refrigerant having passed through thefirst compression part110. Of course, when the external load is small, either the first compression part or the second compression part may be operated.
• Generally, principal factors to determine the efficiency of the compressor are the capacity of the compressor and energy consumption rate. Here, the capacity of the compressor is determined, during the manufacture of the compressor, such that the compressor is suitable for a corresponding air-conditioning system. Consequently, although the compressor has the same capacity as a conventional compressor, it is necessary to reduce energy consumption such that the operating range of the air-conditioning system is extended.
• In the air-conditioning system according to the present invention, the gas-phase refrigerant is supplied to thesecond compression part120 together with the refrigerant compressed by thefirst compression part110. Consequently, compression work applied to the compressor is decreased, and therefore, energy consumption is decreased, whereby the total efficiency of the air-conditioning system is increased although the air-conditioning system has the same output as a conventional air-conditioning system. As a result, the operating range of the air-conditioning system is further extended although the compressor has the same capacity as a conventional compressor.
• Hereinafter, the operation of the compressor in the air-conditioning system according to the present invention will be described with reference toFIGS. 2 and 6.
• In a cooling operation to cool the interior of a room, compression work to be applied to the compressor from the outside, i.e., external load, is proportional to outdoor temperature. However, the external load does not mean only a function of the outdoor temperature. The external load may be determined in consideration of the number of indoor units in operation, indoor temperature, and a predetermined temperature. However, the operation of the compressor will be described hereinafter on the consumption that the external load includes only the outdoor temperature.
• For example, when the outdoor temperature is low, the necessity for cooling the interior of the room is reduced, and therefore, the external load is decreased. When the outdoor temperature is high, on the other hand, a great deal of work must be supplied to the air-conditioning system to cool the interior of the room, and therefore, the external load is increased. In a heating operation to warm the interior of the room, the external load is increased when the outdoor temperature is low, and the external load is decreased when the outdoor temperature is high.
• As previously described in connection withFIG. 2, the air-conditioning system has a refrigerant flow in which the gas-phase refrigerant separated by the phase separator is introduced into thesecond compression part120 while the gas-phase refrigerant separated by the phase separator is mixed with the refrigerant having passed through thefirst compression part110, when the external load is large, i.e., in severely cold regions or tropical regions. Of course, when the external load is small, either the first compression part or the second compression part may be operated.
• InFIG. 6, a rectangular shape drawn according to the external load and the outdoor temperature means compression work to be applied to the compressor from the outside. Rectangle A means compression work applied to the compressor when the first compression part is operated. Rectangles in Section B mean compression works variably supplied to the second compression part depending upon the external load.
• When the external load, i.e., the total compression work, to be applied to the compressor is W1+W2, the compression work of W1is supplied to thefirst compression part110, and the compression work of W2 is supplied to thesecond compression part120.
• When the external load to be applied to the air-conditioning system is within the W1 section, only the first compression part is operated in the air-conditioning system. Of course, the first compression part may be variable depending upon the external load.
• Hereinafter, the operational efficiency of the compressor according to the present invention will be described with reference toFIGS. 2 and 7.
• Generally, principal factors to determine the efficiency of the compressor are the capacity of the compressor and energy consumption rate. Here, the capacity of the compressor is determined, during the manufacture of the compressor, such that the compressor is suitable for a corresponding air-conditioning system. Consequently, although the compressor has the same capacity as a conventional compressor, it is necessary to reduce energy consumption such that the operating range of the air-conditioning system is extended.
• As shown in the drawing, it was possible for a conventional air-conditioning system to be operated only in a region in which the external load has a range of Wi to Wf. In other words, the operating range of the conventional air-conditioning system is determined depending upon only the capacity of the compressor.
• However, it is possible for the air-conditioning system according to this embodiment to be operated in a region in which the external load has a range of Wk to Wf. In the air-conditioning system, the gas-phase refrigerant is supplied to thesecond compression part120 together with the refrigerant compressed by thefirst compression part110. Consequently, compression work applied to the compressor is decreased, and therefore, energy consumption is decreased, whereby the total efficiency of the air-conditioning system is increased although the air-conditioning system has the same output as a conventional air-conditioning system. As a result, the operating range of the air-conditioning system is further extended although the compressor has the same capacity as a conventional compressor.
• Specifically, it can be seen that, when the ratio in volume of thefirst cylinder111 to the second cylinder121 (M:N) is 100:50, the operating range of the air-conditioning system according to the present invention is increased 30% more than that of the conventional air-conditioning system, and the operational efficiency of the air-conditioning system according to the present invention is increased 20% more than that of the conventional air-conditioning system.
• From the viewpoint of coefficient of performance (COP) of the air-conditioning system, it can be seen that the compression work necessary to acquire the same cooling capacity, i.e., power consumption, is decreased, and therefore, the COP of the air-conditioning system is increased. Of course, when the same compression work as the conventional air-conditioning system is supplied to the air-conditioning system according to the present invention, the COP of the air-conditioning system is increased, and therefore, the cooling efficiency of the air-conditioning system is increased.
• Theoretically, the COP of the air-conditioning system is represented by a ratio of heat capacity absorbed by the evaporator to heat capacity of the compression work. Practically, the heat capacity of the compression work means the actual power consumption of the air-conditioning system, whereas the heat capacity absorbed by the evaporator means the cooling capacity of the air-conditioning system.
• In the air-conditioning system according to the present invention, the compressor is driven using the gas-phase refrigerant separated by the phase separator. Consequently, the operational efficiency of the air-conditioning system is increased, and the operating range of the air-conditioning system is extended. Furthermore, as the operating range of the air-conditioning system is extended, it is possible for the air-conditioning system to be operated even in severely cold regions or tropical regions.
• Hereinafter, an embodiment of controlling method for the air-conditioning system according to the present invention will be described in detail with reference toFIGS. 8 and9.
• The air-conditioning system according to the present invention detects data necessary to operate the air-conditioning system, and simultaneously or selectively controls the amount of refrigerant introduced into the phase separator and the amount of refrigerant discharged from the phase separator based on the detected data.
• The data may be operation load of the air-conditioning system necessary to operate the air-conditioning system or data related to the refrigerant. Hereinafter, a process for controlling the air-conditioning system based on the operation load of the air-conditioning system will be described.
• When a user selects operation mode of the air-conditioning system, the control unit C detects operation load of the air-conditioning system (S10).
• The operation mode of the air-conditioning system may be classified into several levels depending upon desired degree of cooling/heating. For example, the operation mode of the air-conditioning system may be set to several levels depending upon the difference between indoor temperature and predetermined temperature.
• The operation load of the air-conditioning system is determined by several factors including indoor temperature, outdoor temperature, the length of the refrigerant pipe, and the number of the indoor units in operation as well as the selected operation mode.
• Specifically, the control unit C is connected to an input unit A for allowing the user to input the operation mode of the air-conditioning system. The control unit C transmits and receives information to and from a temperature sensor B for measuring the outdoor temperature and the indoor temperature.
• When the operation load of the air-conditioning system is detected, the control unit C determines an operation frequency of the compressor corresponding to the operation load of the air-conditioning system, i.e., a first output value D (S30). Here, the operation frequency of the compressor is represented by a function of respective variables of the operation load of the air-conditioning system. The function is a result that is experimentally acquired in advance, and is stored in the control unit C.
• The control unit according to the present invention determines the operation frequency of the compressor in consideration of the capacity of the indoor unit, the outdoor temperature, the indoor temperature, the difference between the indoor temperature and the predetermined temperature, the length of the refrigerant pipe, and the number of the indoor units in operation among the factors affecting the operation frequency of the compressor.
• When the difference between the indoor temperature and the predetermined temperature is large, the operation frequency of the compressor is increased. When the difference between the outdoor temperature and the indoor temperature is large, the operation frequency of the compressor is increased. Also, as the number of the indoor units in operation is increased, the operation frequency of the compressor is increased. In addition, the length of the refrigerant pipe affects the operation frequency of the compressor. Furthermore, compensation coefficients to determine the operation frequency of the compressor may be experimentally acquired, in consideration of the affection of these variables, to determine the operation frequency of the compressor.
• When the operation frequency of the compressor is determined, the control unit C controls the compressor to be operated at the determined operation frequency (S50). After that, the control unit C controls the amount of the gas-phase refrigerant introduced into the intermediate refrigerant pipe (S70).
• Specifically, the control unit C determines the opening amount of the refrigerant control valve corresponding to the operation frequency of the compressor, i.e., a second output value E (S71). Here, relations between the operation frequency of the compressor and the opening amount of the refrigerant control valve are previously stored in the control unit C. The relations between the operation frequency of the compressor and the opening amount of the refrigerant control valve are results that are experimentally acquired in advance.
• For example, control unit C variously adjusts the opening degree of the refrigerant control valve at specific operation frequencies of the compressor, and calculates the cooling capacity of the air-conditioning system depending upon the opening degree of the refrigerant control valve. The opening degree of the refrigerant control valve at which the highest cooling capacity is provided at the specific operation frequencies of the compressor may be selected as the opening degree of the refrigerant control valve corresponding to the operation frequency of the compressor.
• As an example, a process for setting the opening degree of the refrigerant control valve according to the operation frequency of the compressor will be described with reference toFIG. 10.
• FIG. 10 is a graph illustrating the performance of the air-conditioning system when the opening degree of the refrigerant control valve is successively changed while the opening degrees of the first expansion valve and the second expansion valve are uniformly maintained at specific operation frequencies of the compressor.
• It can be seen from the graph ofFIG. 10 that, when the opening degree of the first expansion valve is 22%, the opening degree of the second expansion valve is 20%, and the opening degree of the refrigerant control valve is 40%, the heating capacity and the cooling performance of the air-conditioning system are the highest.
• It can be also seen from the graph ofFIG. 10 that, when the opening degree of the first expansion valve is 22%, the opening degree of the second expansion valve is 26%, and the opening degree of the refrigerant control valve is 30%, the heating capacity and the cooling performance of the air-conditioning system are the highest. It can be also seen from the graph ofFIG. 10 that, when the opening degree of the first expansion valve is 22%, the opening degree of the second expansion valve is 30%, and the opening degree of the refrigerant control valve is 40%, the heating capacity and the cooling performance of the air-conditioning system are the highest. It can be also seen from the graph ofFIG. 10 that, when the opening degree of the first expansion valve is 24%, the opening degree of the second expansion valve is 40%, and the opening degree of the refrigerant control valve is 40%, the heating capacity and the cooling performance of the air-conditioning system are the highest. From the results shown inFIG. 10, it can be seen that the heating capacity and the cooling performance of the air-conditioning system are the highest when the opening degree of refrigerant control valve is approximately 40% at the specific operating frequencies of the compressor.
• The operation frequency of the compressor and the opening amount of the refrigerant control valve correspond to each other in a one-to-one correspondence fashion through the above-described method. The information is stored in the control unit.
• When the opening amount of the refrigerant control valve is determined, the control unit controls the refrigerant control valve such that the refrigerant control valve is opened by the determined opening amount (S73).
• When the user changes the operation mode, on the other hand, the control unit detects the operation load of the air-conditioning system and adjusts the opening degree of the refrigerant control valve based on the detected operation load. Consequently, it is possible for the air-conditioning system according to the present invention to control the amount of the gas-phase refrigerant introduced into the compressor depending upon the operation load of the air-conditioning system, whereby the performance of the air-conditioning system is optimized.
• When any one of the principal factors is changed, the control unit determines a new operation frequency of the compressor in consideration of the changed factor, and newly adjusts the opening degree of the refrigerant control valve based on the determined operation frequency of the compressor. In other words, when any one of the principal factors is changed, the above-described process is repeatedly performed to find the optimal operation state of the air-conditioning system.
• Of course, the compressor may be operated while the operation frequency of the compressor is not changed after it is set based on the initial operation load of the air-conditioning system, and the opening amount of the refrigerant control valve may be changed depending upon the variable amount of the operation load of the air-conditioning system, for example, the indoor temperature and the outdoor temperature.
• Hereinafter, another embodiment of controlling method for the air-conditioning system according to the present invention will be described in detail with reference toFIGS. 2 and 11.
• The air-conditioning system according to the present invention controls the amount of the refrigerant flowing through the refrigerant pipe connected to the phase separator based on data related to the refrigerant. Specifically, a process for controlling the amount of the refrigerant may include a step of controlling the first expansion valve mounted on the mixed refrigerant pipe through which the refrigerant is introduced into the phase separator, a step of controlling the refrigerant control valve mounted on the first refrigerant pipe through which the gas-phase refrigerant separated by the phase separator flows, and a step of controlling the second expansion valve mounted on the second refrigerant pipe through which the liquid-phase refrigerant separated by the phase separator is introduced into the evaporator.
• First, when the operation of the air-conditioning system is initiated, and the refrigerant discharged from thecondenser300 is stored in thephase separator500, a measuring sensor (not shown) mounted in the first refrigerantpipe connection part510 measures the pressure of the refrigerant (S100). Subsequently, the control unit converts the measured pressure into temperature to obtain the temperature of the refrigerant (S200).
• Of course, the measuring sensor may be mounted in at least one of the refrigerant pipes connected to the phase separator. Also, the measuring sensor may directly measure the temperature of the gas-phase refrigerant.
• Subsequently, the control unit determines whether the temperature of the refrigerant in thephase separator500 exceeds a first predetermined temperature T1 (S300). The first predetermined temperature T1 is previously stored in the control unit. Also, the first predetermined temperature T1 of the refrigerant is a value set through experiments. The first predetermined temperature T1 means the temperature of the refrigerant when the liquid-phase refrigerant is discharged through the first refrigerantpipe connection part510 according to the operation condition depending upon the temperature of the outdoor air. Subsequently, the control unit compares the converted refrigerant temperature with the predetermined temperature T1.
• When it is determined, as a result of the comparison, that the converted refrigerant temperature does not exceed the predetermined temperature T1, the control unit completely closes therefrigerant control valve730 through which the gas-phase refrigerant is supplied to thesecond compression part120 of the compressor100 (S400). After that, the control unit adjusts the opening degrees op thefirst expansion valve410 and the second expansion valve420 (S500) to lower the level of the liquid-phase refrigerant in thephase separator500 and increase the amount of the gas-phase refrigerant. For example, the control unit increases the opening degree of thesecond expansion valve420 such that a relatively large amount of the liquid-phase refrigerant is discharged from the phase separator.
• Consequently, the contact between the liquid-phase refrigerant and the lowermost end of the first refrigerantpipe connection part510 is prevented, and the introduction of the liquid-phase refrigerant into thecompressor100 is prevented, whereby the performance of thecompressor100 is prevented from decreasing.
• When it is determined that the measured refrigerant temperature exceeds a second predetermined temperature T2 (S600), the control unit stops controlling the level of the refrigerant and readjusts the opening amounts of the respective valves such that the valves have the opening amounts just before the valves are controlled (S700). In other words, the control unit opens therefrigerant control valve730 by a predetermined opening amount, and closes the first andsecond expansion valve410 and420 by pre-determined opening amounts, respectively.
• When it is determined at S300 that the temperature of the refrigerant in thephase separator500 exceeds the predetermined temperature T1, the operation of the air-conditioning system is performed continuously (S800). After that, when a power off command is inputted by the user (S900), the operation is stopped.
• The multi-stage compression of the air-conditioning system is accomplished through the above-described process, and the performance of the compressor is normally maintained.
• Hereinafter, a further embodiment of controlling method for the air-conditioning system according to the present invention will be described in detail with reference toFIGS. 2 and 12.
• First, when the operation of the air-conditioning system is initiated, thecompressor100 is driven (S1000).
• At this time, the liquid-phase refrigerant may rise due to the abrupt change of the pressure in thephase separator500 with the result that the liquid-phase refrigerant may be introduced into the first refrigerant pipe connection part. In order to prevent the occurrence of this phenomenon, therefore, all the valves connected to the phase separator are closed (S2000).
• Subsequently, a drive signal of 100/500 pulses is inputted to thefirst expansion valve410, and a drive signal of 100/500 pulses is inputted to thesecond expansion valve420 such that the first andsecond expansion valves410 and420 are opened by predetermined amounts V1 and V2, respectively (S3000). These opening degrees of the first andsecond expansion valves410 and420 are maintained until a refrigeration cycle is stabilized. When a drive signal of 500 pulses is inputted to thefirst expansion valve410 and thesecond expansion valve420, the maximum output is accomplished through the first andsecond expansion valves410 and420. Accordingly, inputting a drive signal of 100/500 pulses means inputting a drive signal of 100 pulses with respect to a drive signal ofmaximum 500 pulses. Generally, the expansion valves are not driven by a drive signal of less than 100 pulses. Also, therefrigerant control valve730 remains opened. The reason why therefrigerant control valve730 is not opened is that it takes a greater deal of time to stabilize the refrigeration cycle when therefrigerant control valve730 is opened, which has been experimentally proven.
• At this time, a measuring sensor (not shown) mounted at the outlet side of thecompressor100 measures data related to the refrigerant, i.e., the temperature and the pressure of the refrigerant (S4000). When the measuring sensor is mounted at the outlet side of thecompressor100, it is possible to easily determine whether the refrigerant is suitable for the total operation load of the air-conditioning system.
• Subsequently, the control unit compares the measured data with predetermined reference data to determine whether the refrigeration cycle of the air-conditioning system is stabilized (S5000). Preferably, the reference data related to the temperature or the pressure of the refrigerant is set to a value measured in a normal state in which the liquid-state refrigerant is not introduced from the phase separator.
• When it is determined that the refrigeration cycle is stabilized, i.e., the measured data is within a range of the reference data, the control unit controls therefrigerant control valve730 to be opened by a predetermined amount V3 such that the gas-phase refrigerant is supplied to thesecond compression part120 of the compressor100 (S6000).
• Subsequently, the operation of the compressor is continued while the opening amounts of the valves are adjusted based on the amount of load depending upon the temperature of outdoor air such that the liquid-phase refrigerant is prevented from being introduced into the compressor and the compression work is minimized (S7000).
• It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
INDUSTRIAL APPLICABILITY
• According to the present invention, the refrigerant compressed by the first compression part and the gas-phase refrigerant separated by the phase separator are mixed and compressed in the second compression part. Consequently, the present invention provides the effect of decreasing compression work required in the compressor, thereby relatively increasing the operating range of the air-conditioning system with the result that the air-conditioning system may be used even in severely cold regions. In addition, the amount of the refrigerant introduced into the phase separator and the amount of the refrigerant discharged from the phase separator are simultaneously or selectively controlled depending upon the state of the refrigerant or the load of the air-conditioning system. Consequently, the present invention provides the effect of efficiently operating the air-conditioning system.

Claims (27)

1. An air-conditioning system comprising:

a phase separator for separating a flowing refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant;

an evaporator for evaporating the liquid-phase refrigerant separated by the phase separator;

a compressor having a first compression part into which the refrigerant having passed through the evaporator is introduced and a second compression part into which both the gas-phase refrigerant separated by the phase separator and the refrigerant having passed through the first compression part are introduced; and a control unit for simultaneously or selectively controlling the amount of the refrigerant introduced into the phase separator and the amount of the refrigerant discharged from the phase separator.

2. The air-conditioning system according toclaim 1, further comprising:

a first expansion valve for controlling the amount of the refrigerant introduced into the phase separator;

a second expansion valve for controlling the amount of the liquid-phase refrigerant discharged from the phase separator and introduced into the evaporator; and

a refrigerant control valve for controlling the amount of the gas-phase refrigerant discharged from the phase separator and introduced into the second compression part.

3. The air-conditioning system according toclaim 2, wherein the control unit controls the amount of the gas-phase refrigerant introduced into the second compression part depending upon operation load of the system.

4. The air-conditioning system according toclaim 3, wherein the control unit controls the opening amount of the refrigerant control valve based on a frequency of the compressor determined depending upon the operation load of the system.

5. The air-conditioning system according toclaim 4, wherein the operation load of the system is determined depending upon factors including operation mode set by a user.

6. The air-conditioning system according toclaim 4, wherein the operation load of the system is determined depending upon factors including outdoor temperature and indoor temperature.

7. The air-conditioning system according toclaim 6, further comprising:

a temperature sensor for measuring the outdoor temperature and the indoor temperature.

8. The air-conditioning system according toclaim 2, further comprising:

a measuring sensor for measuring data related to the state of the refrigerant.

9. The air-conditioning system according toclaim 8, wherein the measuring sensor is provided on a first refrigerant pipe through which the gas-phase refrigerant separated by the phase separator flows.

10. The air-conditioning system according toclaim 9, wherein the measuring sensor is a temperature sensor for measuring the temperature of the gas-phase refrigerant.

11. The air-conditioning system according toclaim 8, wherein the measuring sensor is a pressure sensor mounted in at least one of refrigerant pipes connected to the phase separator.

12. The air-conditioning system according toclaim 11, wherein the control unit converts the pressure data measured by the pressure sensor into temperature data corresponding to the pressure data.

13. The air-conditioning system according toclaim 8, wherein the control unit controls the first expansion valve, the second expansion valve, and the refrigerant control valve based on data related to the state of the refrigerant set depending upon the outdoor temperature and the data measured by the measuring sensor.

14. The air-conditioning system according toclaim 8, wherein the measuring sensor includes a pressure sensor and/or a temperature sensor, and the measuring sensor is provided at an outlet port of the compressor.

15. The air-conditioning system according toclaim 14, wherein the control unit closes all the valves to prevent the introduction of the liquid-phase refrigerant into the compressor when the operation of the air-conditioning system is initiated.

16. A controlling method for an air-conditioning system, comprising:

detecting data necessary for the operation of the system; and

simultaneously or selectively controlling the amount of refrigerant introduced into a phase separator and the amount of refrigerant discharged from the phase separator based on the detected data.

17. The controlling method according toclaim 16, wherein the data includes operation load of the system, and the controlling method further comprises:

determining an operation frequency of a compressor corresponding to the operation load of the system; and

operating the compressor at the determined operation frequency.

18. The controlling method according toclaim 16, wherein the step of

controlling the amount of refrigerant includes setting the opening amount of a refrigerant control valve depending upon the operation frequency of the compressor, and

controlling the refrigerant control valve depending upon the set opening amount.

19. The controlling method according toclaim 16, further comprising:

changing operation mode of the air-conditioning system; and

resetting the opening amount of the refrigerant control valve depending upon the changed operation mode of the air-conditioning system.

20. The controlling method according toclaim 16, wherein the data includes data related to the state of the refrigerant, and the controlling method further comprises:

comparing the measured data with data related to the state of the refrigerant previously set depending upon outdoor temperature; and

controlling valves provided on refrigerant pipes connected to the phase separator based on the measured data and the set data

21. The controlling method according toclaim 20, wherein the data includes the temperature of the refrigerant, and the step of controlling the valves includes when the temperature of the refrigerant does not exceed a first predetermined temperature previously stored in the control unit, closing a refrigerant control valve through which a gas-phase refrigerant is discharged from the phase separator, and opening a first expansion valve through which the refrigerant is introduced into the phase separator and a second expansion valve through which a liquid-phase refrigerant is discharged from the phase separator and introduced into an evaporator by predetermined opening degrees, respectively.

22. The controlling method according toclaim 21, wherein the step of controlling the valves includes when the temperature of the refrigerant exceeds a second predetermined temperature previously stored in the control unit, resetting the opening degrees of the refrigerant control valve, the first expansion valve, and the second expansion valve to be the opening degrees just before the valves are controlled.

23. The controlling method according toclaim 16, wherein the step of controlling the amount of refrigerant includes controlling a first expansion valve mounted on a mixed refrigerant pipe through which the refrigerant is introduced into the phase separator,

controlling a refrigerant control valve mounted on a first refrigerant pipe through which a gas-phase refrigerant separated by the phase separator flows, and controlling a second expansion valve mounted on a second refrigerant pipe through which a liquid-phase refrigerant separated by the phase separator flows to an evaporator.

24. The controlling method according toclaim 23, wherein all the valves are closed to prevent the introduction of the liquid-phase refrigerant into the compressor when the operation of the air-conditioning system is initiated.

25. The controlling method according toclaim 24, wherein the first expansion valve and the second expansion valve are opened to predetermined opening degrees, respectively, until the measured data is within a range of reference data of the stabilized system after all the valves are closed.

26. The controlling method according toclaim 25, wherein, when the measured data is within the range of reference data, the refrigerant control valve is opened to a predetermined opening degree.

27. The controlling method according toclaim 26, wherein, after the refrigerant control valve is opened to the predetermined opening degree, the opening degrees of the first expansion valve, the second expansion valve, and the refrigerant control valve are controlled depending upon outdoor temperature.

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