Air conditioner and method of operating an air conditioner

An air conditioner and a method of operating an air conditioner are provided. The air conditioner may include at least one indoor device having an indoor heat exchanger that evaporates or condenses a refrigerant by heat exchange with indoor air; at least one outdoor device having a variable capacity compression device that sucks in and compresses a refrigerant of a refrigerant intake passage and discharges the refrigerant to a refrigerant discharge passage, a water-refrigerant heat exchanger that condenses or evaporates a refrigerant by heat exchange with heat source water, and an outdoor expansion device installed between the indoor heat exchanger of the at least one indoor device and the water-refrigerant heat exchanger; a heat source water flow path connected to the water-refrigerant heat exchanger; a pump installed on the heat source water flow path; and a variable flow valve installed on the heat source water flow path. An opening degree of the variable flow valve is varied depending on a pressure of at least one of the refrigerant discharge passage or the refrigerant intake passage.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority under 35 U.S.C. §119 to Korean Application No. 10-2011-0106030 filed in Korea on Oct. 17, 2011, whose entire disclosure is hereby incorporated by reference.

BACKGROUND

An air conditioner and a method of operating an air conditioner are disclosed herein.

Air conditioners are known. However, they suffer from various disadvantages.

DETAILED DESCRIPTION

Hereinafter, an air conditioner according to embodiments will be described below with reference to the accompanying drawings. Where possible, like reference numerals have been used to indicate like elements.

Generally, an air conditioner is an appliance that cools or heats a room using a refrigerating cycle of a refrigerant, which performs a cooling operation or a heating operation by sequentially compressing, condensing, expanding, and evaporating the refrigerant and absorbing surrounding heat when the refrigerant is vaporized and releasing the heat when the refrigerant is liquefied. Such an air conditioner is able to condense or evaporate the refrigerant with outdoor air, and also to condense or evaporate the refrigerant with heat source water.

Such an air conditioner may include a water-refrigerant heat exchanger that provides heat exchange between heat source water and a refrigerant, and which is installed between a compressor and an expansion device to allow the refrigerant to be condensed or evaporated with the water. The water-refrigerant heat exchanger may be, for example, a plate-type heat exchanger, in which a refrigerant flow path, through which a refrigerant may flow, and a heat source water flow path, through which heat source water may flow, may be separated by a heat transfer plate. An inflow path that supplies heat source water to the water-refrigerant heat exchanger and an outflow path that allows the heat source water heat-exchanged with the refrigerant to flow out of the plate-type heat exchanger may be provided. A pump that pumps the heat source water to the water-refrigerant heat exchanger and a variable flow valve that regulates a flow rate of the heat source water coming in and out of the water-refrigerant heat exchanger may be installed in the inflow path or the outflow path.

Korean Patent Application Publication No. 10-2010-0005820 discloses an air conditioner that regulates an opening degree of a variable flow valve using an operating rate of a compressor depending on an operation capacity of an indoor unit or device, or using a temperature sensed in a water recovery tube. However, the air conditioner disclosed in Korean Patent Application Publication No. 10-2010-0005820 has a problem that a flow control valve is controlled regardless of a pressure of an outdoor unit or device, and it is difficult to optimize a refrigerant cycle.

FIG. 1is a schematic diagram showing a refrigerant flow and a heat source water flow during a cooling operation of an air conditioner according to an embodiment.FIG. 2is a schematic diagram showing a refrigerant flow and a heat source water flow during a heating operation of the air conditioner according to an embodiment.

The air conditioner ofFIGS. 1-2may include a compression device2that compresses a refrigerant, a water-refrigerant heat exchanger20that condenses or evaporates the refrigerant by heat exchange with water (hereinafter, referred to as heat source water), an indoor heat exchanger30that evaporates or condenses the refrigerant by heat exchange with indoor air, and expansion devices40and42installed between the water-refrigerant heat exchanger20and the indoor heat exchanger39. The air conditioner may further include a cooling/heating switching valve50that switches between a cooling operation and a heating operation.

The compression device2may suck and compress the refrigerant from a refrigerant intake passage4and then discharges it to a refrigerant discharge passage5. The compression device2may be configured to be variable in capacity. The compression device2may include at least one compressor6and7connected to the refrigerant intake passage4and the refrigerant discharge passage5.

The at least one compressor6and7may include one inverter compressor having a variable compression capacity, or may include an inverter compressor with variable compression capacity and a constant speed compressor having a constant compression capacity. The exemplary embodiment ofFIGS. 1-2includes an inverter compressor6and a constant speed compressor7.

The refrigerant intake passage4may be connected in parallel to the inverter compressor6and the constant speed compressor7. The refrigerant intake passage4may include an inverter compressor intake passage8connected to the inverter compressor6, a constant speed compressor intake passage path9connected to the constant speed compressor7, and a common intake passage10connected to the inverter compressor intake passage8and the constant speed compressor intake passage9.

An accumulator11that accumulates liquid refrigerant from the refrigerant may be installed on the refrigerant intake passage4. The accumulator11may be installed on the common intake passage10.

The refrigerant discharge passage5may be connected in parallel to the inverter compressor6and the constant speed compressor7. The refrigerant discharge passage5may include an inverter compressor discharge passage12connected to the inverter compressor6, a constant speed compressor discharge passage13connected to the constant speed compressor7, and a common discharge passage14connected to the inverter compressor discharge passage12and the constant speed discharge passage13.

An inverter compressor oil separator15may be installed on the refrigerant discharge passage5to separate oil from the refrigerant discharged from the inverter compressor6and return it to the refrigerant intake passage4. A constant speed compressor oil separator16may be installed on the refrigerant discharge passage5to separate oil from the refrigerant discharged from the constant speed compressor7and return it to the refrigerant intake passage4.

The water-refrigerant heat exchanger20may function as a condenser that condenses the refrigerant by heat exchange between the heat source water and the refrigerant in a cooling operation, and as an evaporator that evaporates the refrigerant by heat exchange between the heat source and the refrigerant in a heating operation. The water-refrigerant heat exchanger20may condense the refrigerant flowing from the cooling/heating switching valve50by heat exchange with the heat source water in the cooling operation, and evaporate the refrigerant flowing from the expansion devices40and42by heat exchange with the heat source water in the heating operation. The water-refrigerant heat exchanger20may be include a refrigerant heat exchange passage that condenses or evaporates a refrigerant passing therethrough and a heat source water heat exchange passage that heats or cools heat source water passing therethrough.

The water-refrigerant heat exchanger20may be a plate-type heat exchanger or a shell tube-type heat exchanger. In the case that the water-refrigerant heat exchanger20is a plate-type heat exchanger, the refrigerant heat exchange passage and the heat source water heat exchange passage may be separated by a plate-type heat transfer member, and the refrigerant and water may be heat-exchanged through the heat transfer member. In the case that the water-refrigerant heat exchanger20is a shell tube-type heat exchanger, the refrigerant heat exchange passage and the heat source water heat exchange passage may be separated by a tube disposed within a shell, and the refrigerant and the heat source water may be heat exchanged through the tube.

The indoor heat exchanger30may function as an evaporator that evaporates the refrigerant by heat exchange between indoor air and the refrigerant in the cooling operation, and as a condenser that condenses the refrigerant by heat exchange between the indoor air and the refrigerant in the heating operation. The indoor heat exchanger30may evaporate the refrigerant flowing from the expansion devices40and42by heat exchange with the indoor air in the cooling operation, and condense the refrigerant flowing from the cooling/heating switching valve50by heat exchange between the refrigerant and the indoor air in the heating operation. The indoor heat exchanger30may heat-exchange the refrigerant with the indoor air by an indoor fan32that blows indoor air to the indoor heat exchanger30.

The expansion devices40and42may include one refrigerant expansion device installed between the water-refrigerant heat exchanger20and the indoor heat exchanger30, and may include an outdoor expansion device40installed closer to the water-refrigerant heat exchanger20than to the indoor heat exchanger30and an indoor expansion device42installed closer to the indoor heat exchanger30than to the water-refrigerant heat exchanger20. The outdoor expansion device40may be installed between the water-refrigerant heat exchanger20and the indoor heat exchanger30and expand the refrigerant flowing toward the water-refrigerant heat exchanger20. The outdoor expansion device40may be connected to the water-refrigerant heat exchanger20by a water-refrigerant heat exchange connection pipe44. The outdoor expansion device40may be connected to the indoor expansion device42by an expansion device connection pipe46. The indoor expansion device42may be installed between the outdoor expansion device40and the indoor heat exchanger30and may expand the refrigerant flowing toward the indoor heat exchanger30. The indoor expansion device42may be connected to the indoor heat exchanger30by an indoor heat exchanger connection pipe48.

The cooling/heating switching valve50may be connected to the refrigerant intake passage4, the refrigerant discharge passage5, the water-refrigerant heat exchanger20, and the indoor heat exchanger30. The cooling/heating switching valve50may be connected to the common intake passage10of the refrigerant intake passage4. The cooling/heating switching valve50may be connected to the common discharge passage14of the refrigerant discharge passage5. The cooling/heating switching valve50may be connected to the water-refrigerant heat exchanger20by a water-refrigerant heat exchanger connection pipe52. The cooling/heating switching valve50may be connected to the indoor heat exchanger30by an indoor heat exchanger connection pipe54.

In a cooling operation, the cooling/heating switching valve50may guide the refrigerant compressed in the compression device2and discharged to the refrigerant discharge passage5to flow to the water-refrigerant heat exchanger20and guide the refrigerant flowing from the indoor heat exchanger30to flow to the refrigerant intake passage4. In a heating operation, the cooling/heating switching valve50may guide the refrigerant compressed in the compression device2and discharged to the refrigerant discharge passage5to flow to the indoor heat exchanger30and guide the refrigerant flowing from the water-refrigerant heat exchanger20to flow to the refrigerant intake passage4.

The air conditioner may include a low-pressure sensor60that senses a pressure in the refrigerant intake passage4, and a high-pressure sensor62that senses a pressure in the refrigerant discharge passage5. The low-pressure sensor60may be installed on the refrigerant intake passage4, more specifically, on the common intake passage10of the refrigerant intake passage4to sense the pressure of the refrigerant passing through the common intake passage10. The high-pressure sensor62may be installed on the refrigerant discharge passage5, more specifically, on the common discharge passage14of the refrigerant discharge passage5to sense the pressure of the refrigerant passing through the common discharge passage14.

The air conditioner may further include an intake temperature sensor64installed on the refrigerant intake passage4and discharge temperature sensors66and68installed on the refrigerant discharge passage5. The intake temperature sensor64may be installed on the common intake passage10of the refrigerant intake passage4and sense the temperature of the refrigerant passing through the common intake passage10. The discharge temperature sensors66and68may include an inverter compressor discharge temperature sensor66installed on the inverter compressor discharge passage12of the refrigerant intake passage4to sense the temperature of the refrigerant passing through the inverter compressor discharge passage12, and a constant speed compressor discharge temperature sensor68installed on the constant speed compressor discharge passage13of the refrigerant intake passage4to sense the temperature of the refrigerant passing through the constant speed compressor discharge passage13.

The air conditioner may further include a heat source water flow path80connected to the water-refrigerant heat exchanger20; a pump90installed on the heat source water flow path80; and a variable flow valve100installed on the heat source water flow path20and capable of regulating the opening degree thereof.

The heat source water flow path80may be connected to external heat exchange equipment82that heat-exchanges the heat source water, which is heat-exchanged with the refrigerant in the water-refrigerant heat exchanger20, with outdoor air or ground heat. The heat source water flow path80may include an inflow path84that allows the heat source water having passed through the external heat exchange equipment82to flow into the water-refrigerant heat exchanger20and an outflow path86that allows the heat source water heat-exchanged with the refrigerant in the water-refrigerant heat exchanger20to flow out to the external heat exchange equipment82. The external heat exchange equipment82may include a cooling tower that cools the heat source water having flowed out through the outflow path86with outdoor air, a ground heat exchanger that exchanges the heat source water having flowed out through the outflow path86with ground heat, or a boiler that heats the heat source water having flowed out through the outflow path86, or may be a combination of the cooling tower, the ground heat exchanger, and the boiler.

A pump90may pump heat source water so that the heat source water circulates through the water-refrigerant heat exchanger20and the external heat exchange equipment82. The pump90may be installed on at least one of the inflow path84or the outflow path86. The pump90may be a variable capacity pump, or an inverter pump that varies in capacity depending on input frequency, or a plurality of constant speed pumps having a variable pumping capacity. The pump90may include a pressure sensor that senses pressure. If a pressure drop becomes larger due to a decrease in the opening degree of the variable flow valve100, the pressure sensor may sense this, a number of turns of the pump90may be decreased, and the power consumption input to the pump90may be minimized. On the other hand, if a pressure drop becomes smaller due to an increase in the opening degree of the variable flow valve100, the pressure sensor may sense this, and the number of turns of the pump90may be increased.

The variable flow valve100may regulate the heat source water flowing in and out of the water-refrigerant heat exchanger20. The variable flow valve100may vary the flow rate of the heat source water circulating through the heat source water flow path80by adjusting the opening degree. The variable flow valve100may be installed on at least one of the inflow path84or the outflow path86.

The variable flow valve100may be opened to a maximum opening degree when fully opened, and opened to a minimum opening degree when fully closed. The variable flow valve100may maximize the flow rate of the heat source water flow path80when the opening degree is maximum, and minimize the flow rate of the heat source water flow path80when the opening degree is minimum.

The variable flow valve100may be fully opened at a start-up of a cooling operation or a heating operation. That is, the variable flow valve100may be opened to the maximum opening degree at the start-up of the cooling operation or the heating operation, thereby maximizing the flow rate of the heat source water of the heat source water flow path80. When the start-up of the cooling operation or the heating operation is completed, the opening degree may be varied and the variable flow valve100may regulate the flow rate of the heat source flow path80to be different from that for the start-up of the cooling operation or the heating operation.

When increasing or decreasing the opening degree of the variable flow valve100, the variable flow valve100may be regulated to an opening degree obtained by increasing or decreasing the current opening degree by a predetermined opening degree amount. When increasing or decreasing the opening degree of the variable flow valve100a plurality of times, the opening degree may be gradually increased or decreased in increments of a set opening degree amount.

The opening degree of the variable flow valve100may be varied depending on a pressure of at least one of the refrigerant discharge passage5or the refrigerant intake passage4. In a cooling operation, the opening degree of the variable flow valve100may be varied depending on the pressure of the refrigerant discharge passage5. In the cooling operation, if the pressure of the refrigerant discharge passage5is lower than a target condensation pressure, the opening degree of the variable flow valve100may be decreased. In the cooling operation, if the pressure of the refrigerant discharge passage5is lower than the target condensation pressure, the opening degree of the variable flow valve100may be decreased. In the cooling operation, the opening degree of the variable flow valve100may be varied depending on a sensed pressure of the high-pressure sensor62and the target condensation pressure. The sensed pressure of the high-pressure sensor62may become the pressure of the refrigerant discharge passage5.

In the cooling operation, the target condensation pressure may be determined according to a magnitude of the load of the indoor device O, especially, the indoor heat exchanger30, and the opening degree of the variable flow valve100may be increased or decreased based on a comparison between the sensed pressure and the target condensation pressure. In the cooling operation, if the sensed pressure of the high-pressure sensor62is higher than the target condensation pressure, the opening degree of the variable flow valve100may be increased. In the cooling operation, if the pressure sensed by the high-pressure sensor62is lower than the target condensation pressure, the opening degree of the variable flow valve100may be decreased. In the cooling operation, upon an increase in the opening degree, if the current opening degree of the variable flow valve100is the maximum opening degree, the current opening degree may be maintained. In the cooling operation, upon a decrease in the opening degree, if the current opening degree of the variable flow valve100is the minimum opening degree, the current opening degree may be maintained.

In the heating operation, the opening degree of the variable flow valve100may be varied depending on a pressure in or of the refrigerant intake passage4. If the pressure of the refrigerant intake passage4is higher than a target evaporation pressure, the opening degree of the variable flow valve100may be decreased. If the pressure of the refrigerant intake passage4is lower than the target evaporation pressure, the opening degree of the variable flow valve100may be increased.

In the heating operation, the opening degree of the variable flow valve100may be varied depending on a sensed pressure of the low-pressure sensor60and the target evaporation pressure. The sensed pressure of the low-pressure sensor60may become the pressure of the refrigerant intake passage4. The target evaporation pressure may be determined according to a magnitude of a load of the indoor device O, especially, the indoor heat exchanger30, and the opening degree of the variable flow valve100may be increased or decreased based on a comparison between the sensed pressure and the target evaporation pressure. In the heating operation, if the sensed pressure of the low-pressure sensor60is higher than the target evaporation pressure, the opening degree of the variable flow valve100may be decreased. In the heating operation, if the sensed pressure of the low-pressure sensor60is lower than the target evaporation pressure, the opening degree of the variable flow valve100may be increased. In the heating operation, upon an increase in the opening degree, if the current opening degree of the variable flow valve100is the maximum opening degree, the current opening degree may be maintained. In the heating operation, upon a decrease in the opening degree, if the current opening degree of the variable flow valve100is the minimum opening degree, the current opening degree may be maintained. The variable flow valve100may be fully closed when the air conditioner is stopped.

The indoor heat exchanger30may be installed in the indoor device I. The indoor expansion device42, together with the indoor heat exchanger30, may be installed in the indoor device I. The indoor fan32may be installed in the indoor device I to blow indoor air to the indoor heat exchanger30. In the air conditioner, the compression device2and the water-refrigerant heat exchanger20may be installed in the outdoor device O. The outdoor expansion device40, the cooling/heating switching valve50, the low-pressure sensor60, and the high-pressure sensor62, together with the compression device2and the water-refrigerant heat exchanger20, may be installed in the outdoor device O. The intake temperature sensor64and the discharge temperature sensors66and68may be installed in the outdoor device O. The heat source water flow path80may be disposed to penetrate the outdoor device O, the pump90and the variable flow valve100may be installed at a portion of the heat source water flow path80, which is positioned outside of the outdoor device O, and the outdoor heat exchange equipment82may be installed to be positioned outside the outdoor device O. The outdoor device O may be connected to the variable flow valve100installed outside the outdoor device O by a control line, and the variable flow vale100may be controlled by the outdoor device O.

FIG. 3is a control block diagram of an air conditioner according to an embodiment. The air conditioner according to this embodiment may include an outdoor device controller110that controls the compression device2and a variable flow valve controller120that controls the variable flow valve100. The outdoor device controller110may control the cooling/heating switching valve50and the outdoor expansion valve40. The outdoor device controller100may control at least one of the compression device2, the cooling/heating switching valve50, or the outdoor expansion device40according to a sensing result of at least one of low-pressure sensor60, high-pressure sensor62, intake temperature sensor64, or discharge temperature sensors66and68.

The variable flow valve controller120may communicate with the outdoor device controller110via wired or wireless communication. The variable flow valve controller120may be connected to the variable flow valve100by a signal line.

The low-pressure sensor60and the high-pressure sensor62may be connected to the variable flow valve controller120by a signal line to output a sensed pressure to the variable flow valve controller120. The variable flow valve controller120may determine the opening degree of the variable flow valve100based on the sensed pressure and output a signal corresponding to the determined opening degree to the variable flow valve100.

The low-pressure sensor60and the high-pressure sensor62may be connected to the outdoor device controller110by a signal line to output a sensed pressure to the outdoor device controller110. The outdoor device controller110may output the sensed pressure of the low-pressure sensor60and the high-pressure sensor62to the variable flow valve controller120. The variable flow valve controller120may determine the opening degree of the variable flow valve100based on the sensed pressure to output a signal corresponding to the determined opening degree to the variable flow valve100.

FIG. 4is a flow chart of a cooling operation in a method of operating an air conditioner according to an embodiment.FIG. 5is a flow chart of a heating operation in a method of operating an air conditioner according to an embodiment.

The method according to embodiments may include steps S1to S4and S21to S24of starting up the air conditioner, and steps S5to S12and S25to S32of rated-controlling after the startup control steps S1to S4and S21to S24.

In the startup control steps S1to S4and S21and S24, upon startup of the air conditioner, a variable flow valve, such as variable flow value100ofFIG. 1, regulating the heat source water entering and exiting the water-refrigerant heat exchanger20may be fully opened, in steps S1, S2, S21, and S22. Upon starting a cooling operation of the air conditioner, a compression device, such as compression device2ofFIG. 1, may be started up, a pump, such as pump90ofFIG. 1, may be started up, and the variable flow valve may be opened to maximum opening, in steps S1and S2.

In the cooling operation, a refrigerant may be compressed in the compression device, such as compression device2ofFIGS. 1-2, condensed by heat exchange with heat source water in a water-refrigerant heat exchanger, such as water-refrigerant heat exchanger20ofFIG. 1, expanded in an indoor expansion device, such as indoor expansion device42ofFIG. 1, and evaporated in an indoor heat exchanger, such as indoor heat exchanger30ofFIG. 1. As the variable flow valve is opened to the maximum opening degree, the refrigerant may be quickly heat-exchanged with a large quantity of heat source water, and the water-refrigerant heat exchanger may quickly condense the refrigerant. As time gradually passes, a high pressure sensed by a high-pressure sensor, such as high-pressure sensor62ofFIG. 1, may rise, and a low pressure sensed by a low-pressure sensor, such as low-pressure sensor60ofFIG. 1, may drop. If the rising gradient of the pressure sensed by the high-pressure sensor is between an upper limit gradient and a lower limit gradient, the pressure of the refrigerant may be deemed as stable. Once the refrigerant pressure of the air conditioner becomes stable, the startup control step in the cooling operation may be completed, in steps S3and S4.

Upon starting a heating operation of the air conditioner, the compression device may be started, the pump started, and the variable flow valve opened to the maximum opening degree, in steps S21and S22. A refrigerant may be compressed in the compression device, condensed by heat exchange with indoor air in the indoor heat exchanger, expanded in the outdoor expansion device, and evaporated in the water-refrigerant heat exchanger. As the variable flow valve may be opened to the maximum opening degree, the refrigerant may be quickly heat-exchanged with a large quantity of heat source water, and the water-refrigerant heat exchanger may quickly condense the refrigerant. As time gradually passes, a high pressure sensed by the high-pressure sensor may rise, and a low pressure sensed by the low-pressure sensor may drop. If the rising gradient of the pressure sensed by the high-pressure sensor is between an upper limit gradient and a lower limit gradient, the pressure of the refrigerant is deemed as stable. Once the refrigerant pressure of the air conditioner becomes stable, the startup control step in the heating operation may be completed, in steps S23and S24.

In the rated control steps S5to S12and S25to S32, after the startup control steps S1to S4and S21to S24, the opening degree of the variable flow valve may be varied depending on the pressure of the refrigerant flowing from the compression device to the water-refrigerant heat exchanger, or the opening degree of the variable flow valve may be varied depending on the pressure of the refrigerant flowing from the water-refrigerant heat exchanger to the compression device.

During the cooling operation, in the rated control steps S5to S12, the opening degree of the variable flow valve may be varied depending on the pressure of the refrigerant flowing from the compression device to the water-refrigerant heat exchanger. During the heating operation, in the rated control steps S25to S32, the opening degree of the variable flow valve may be varied depending on the pressure of the refrigerant flowing from the water-refrigerant heat exchanger to the compression device.

First, during the cooling operation, in the rated control steps S5to S12, if the pressure sensed by the high-pressure sensor is higher than a target condensation pressure, the opening degree of the variable flow valve may be increased. At this point, in the rated control steps S5to S12, upon an increase in the opening degree of the variable flow valve, if the current opening degree of the variable flow valve is maximum, the current opening degree may be maintained, in steps S5, S6, and S7.

Also, during the cooling operation, in the rated control steps S5to S12, if the pressure sensed by the high-pressure sensor is lower than the target condensation pressure, the opening degree of the variable flow valve may be decreased. At this point, in the rated control steps S5to S12, upon a decrease in the opening degree of the variable flow valve, if the current opening degree of the variable flow valve is minimum, the current opening degree may be maintained, in step S8.

During the cooling operation, in the rated control steps S5to S12, after an increase or decrease in the opening degree of the variable flow valve100, the air conditioner may remain in standby until the pressure of the refrigerant becomes stable, in step S9.

Upon a change in the opening degree of the variable flow valve, the pressure of the refrigerant may be changed, and the difference between the pressure sensed by the high-pressure sensor and a target condensation pressure may become smaller than a set value, or the difference between the pressure sensed by the low-pressure sensor and a target evaporation pressure may become smaller than a set value. In this case, the pressure of the refrigerant may become stable.

During the cooling operation, in the rated control steps S5to S12, unless a stop signal of the air conditioner is input, comparison between the condensation pressure sensed by the high-pressure sensor and the target condensation pressure and the corresponding increase or decrease in the opening degree of the variable flow valve and standby may be repeated, in steps S10, S7, S8, and S9.

During the cooling operation, in the rated control steps S5to S12, when the air conditioner is stopped, i.e., a stop signal of the air conditioner may be input, the variable flow valve may be fully closed and the cooling operation may be completed, in steps S11and S12. The variable flow valve may be regulated to have the minimum opening degree.

Meanwhile, during the heating operation, in the rated control steps S25to S32, if the pressure sensed by the low-pressure sensor is higher than a target evaporation pressure, the opening degree of the variable flow valve may be decreased. At this point, in the rated control steps S25to S32, upon a decrease in the opening degree of the variable flow valve, if the current opening degree of the variable flow valve is minimum, the current opening degree may be maintained, in steps S25, S26, and S27.

Also, during the heating operation, in the rated control steps S25to S32, if the pressure sensed by the low-pressure sensor is lower than the target evaporation pressure, the opening degree of the variable flow valve may be increased. At this point, in the rated control steps S25to S32, upon an increase in the opening degree of the variable flow valve, if the current opening degree of the variable flow valve is minimum, the current opening degree may be maintained, in step S28.

During the heating operation, in the rated control steps S25to S32, after an increase or decrease in the opening degree of the variable flow valve, the air conditioner may remain in standby until the pressure of the refrigerant becomes stable, in step S29. Upon a change in the opening degree of the variable flow valve100, the pressure of the refrigerant may be changed, and the difference between the pressure sensed by the high-pressure sensor and a target condensation pressure may become smaller than a set value, or the difference between the pressure sensed by the low-pressure sensor and a target evaporation pressure may become smaller than a set value. In this case, the pressure of the refrigerant may become stable.

During the heating operation, in the rated control steps S25to S32, unless a stop signal of the air conditioner is input, comparison between the evaporation pressure sensed by the low-pressure sensor and the target evaporation pressure and the corresponding increase or decrease in the opening degree of the variable flow valve and standby may be repeated in step S30, S27, S28, and S29.

During the heating operation, in the rated control steps S25to S32, when the air conditioner is stopped, i.e., a stop signal of the air conditioner is input, the variable flow valve may be fully closed and the heating operation completed, in steps S31and S32. The variable flow valve may be regulated to have the minimum opening degree.

Embodiments disclosed herein provide an air conditioner, which enables optimization of a refrigerant cycle by controlling an opening degree of a variable flow valve based on a pressure of an outdoor unit or device, and a method of operating an air conditioner.

Embodiments disclosed herein provide an air conditioner that may include an indoor unit or device having an indoor heat exchanger that evaporates or condenses a refrigerant by heat exchange with indoor air; an outdoor unit or device having a variable capacity compression device that sucks and compresses a refrigerant of a refrigerant intake passage and discharges the refrigerant to a refrigerant discharge passage, a water-refrigerant heat exchanger that condenses or evaporates a refrigerant by heat exchange with heat source water, and an outdoor expansion device installed between the indoor heat exchanger and the water-refrigerant heat exchanger; a heat source water flow path connected to the water-refrigerant heat exchanger; a pump installed on the heat source water flow path; and a variable flow valve installed on the heat source water flow path and capable of regulating the opening degree. The opening degree of the variable flow valve may be varied depending on the pressure of at least one of the refrigerant discharge passage or the refrigerant intake passage.

During a cooling operation, if the pressure of the refrigerant discharge passage is higher than a target condensation pressure, the opening degree of the variable flow valve may be increased. During the cooling operation, if the pressure of the refrigerant discharge passage is lower than a target condensation pressure, the opening degree of the variable flow valve may be decreased.

During a heating operation, if the pressure of the refrigerant intake passage is higher than a target evaporation pressure, the opening degree of the variable flow valve may be decreased. During the heating operation, if the pressure of the refrigerant intake passage is higher than the target evaporation pressure, the opening degree of the variable flow valve may be decreased.

The variable flow valve may be fully opened upon startup of the cooling operation, and the opening degree may be varied upon completion of the startup of the cooling operation. The variable flow valve may be fully opened upon startup of the heating operation, and the opening degree may be varied upon completion of the startup of the heating operation.

The air conditioner may further include an outdoor controller that controls the outdoor unit, and a variable flow valve controller that controls the variable flow valve.

The outdoor unit may further include a low-pressure sensor that senses the pressure of the refrigerant intake passage, and a high-pressure sensor that senses the pressure of the refrigerant discharge passage. The variable flow valve controller may vary the opening degree of the variable flow valve according to a sensing result of the high-pressure sensor during the cooling operation, and vary the opening degree of the variable flow valve according to a sensing result of the low-pressure sensor during the heating operation.

The variable flow valve controller may communicate with the outdoor unit or device controller. The variable flow valve controller, together with the outdoor unit controller, may be installed in the outdoor unit. When the opening degree of the variable flow valve is varied, the opening degree may be increased or decreased by a set amount.

Embodiments disclosed herein may further provide a method of operating an air conditioner. The method may include a startup control step of fully opening a variable flow valve for regulating heat source water entering or exiting a water-refrigerant heat exchanger for heat exchange between a refrigerant and heat source water in a cooling operation of the air conditioner, and a rated control step of, after the startup control step, increasing the opening degree of the variable flow valve if the pressure of the refrigerant flowing from a compression part or device compressing the refrigerant to the water-refrigerant heat exchanger is higher than a target condensation pressure and decreasing the opening degree of the variable flow valve if the pressure of the refrigerant flowing from the compression part to the water-refrigerant heat exchanger is lower than the target condensation pressure.

Embodiments disclosed herein additionally provide a method of operating an air conditioner. The method may include a startup control step of fully opening a variable flow valve for regulating heat source water entering or exiting a water-refrigerant heat exchanger for heat exchange between a refrigerant and heat source water in a heating operation of the air conditioner, and a rated control step of, after the startup control step, decreasing the opening degree of the variable flow valve if the pressure of the refrigerant flowing from the water-refrigerant heat exchanger to a compression part or device compressing the refrigerant is higher than a target evaporation pressure and increasing the opening degree of the variable flow valve if the pressure of the refrigerant flowing from the water-refrigerant heat exchanger to the compression part is lower than the target evaporation pressure. In the rated control step, if the current opening degree of the variable flow valve is maximum upon an increase in the opening degree of the variable flow valve, the current opening degree may be maintained. In the rated control step, if the current opening degree of the variable flow valve is minimum upon a decrease in the opening degree of the variable flow valve, the current opening degree may be maintained. The rated control step may be completed by fully closing the variable flow valve when the air conditioner is stopped.

By regulating the opening degree of the variable flow valve based on the operation rate of a compressor or a temperature measured in the heat source water flow path, the air conditioner may be operated while maximizing a cycle of a refrigerant, and reliability of a outdoor unit or device may be improved. Moreover, the variable flow valve may be easily controlled by the outdoor unit or device without sensing the temperature in the heat source water flow path, because the outdoor unit may control the variable flow valve according to a sensing result of a low-pressure sensor or a high-pressure sensor.

Furthermore, power consumption of the pump may be reduced by a decrease in a number of turns of the pump upon a decrease in the opening degree of the variable flow valve, and the power consumption of the pump may be further minimized by keeping the number of turns of the pump constant with respect to the opening degree of the variable flow valve.