Patent Description:
There are air-conditioning apparatuses known as having a chiller. These air-conditioning apparatuses use a heat source device installed outside a building to cool or heat water in the chiller.

The chiller is connected to a load, such as a fan coil unit in an indoor unit or a panel heater, by a feed pipe and a return pipe through which water flows. The cooled or heated water flows through the feed pipe and is delivered to the load to cool or heat the load. The water having cooled or heated the load flows through the return pipe and flows back to the chiller. At the site where the load is provided, a control panel is installed. The control panel controls one or more chillers, and outputs an operating command including information on a target outlet water temperature to the one or more chillers.

Document <CIT> shows a flow rate ratio of first to third primary pumps being adjusted to make a water temperature at an outlet of an evaporator in a first heat source-side flow channel, a water temperature at an outlet of an evaporator in a second heat source-side flow channel, and a water temperature at an outlet of an evaporator in a third heat source-side flow channel, different from each other, thus a total value of power consumption of first to third chiller units can be reduced even when a water temperature after joining at an upstream-side going header, is kept at a target temperature, while keeping flow rates of heat mediums of the first to third heat source-side flow channels in a lowest flow rate or more.

Document <CIT> discloses a chiller system according to the preamble of claim <NUM>. This document shows a target cold water temperature being determined within the range of an upper limit cold water temperature, and the upper limit cold water temperature is determined on the basis of a temperature of the air cooled by an indoor heat exchanger. For this reason, the cooling system is operated in such a manner that the cold water has the upper limit cold water temperature or a temperature near the upper limit cold water temperature, and as a result, power consumption can be reduced while keeping necessary cooling capacity.

Document <CIT> shows an air-conditioning apparatus including a heat medium temperature adjustment operation mode in which when the temperature of a heat medium falls outside a predetermined temperature range while a compressor and a pump are kept stopped, the compressor and the pump are driven to cause an intermediate heat exchanger to exchange heat between a refrigerant and the heat medium so that the heat medium is heated or cooled to have a temperature that falls within the temperature range.

However, the highest outlet water temperature and the lowest outlet water temperature in the chillers may vary depending on the operating conditions such as the outside air temperature and the outlet and inlet water temperatures. Therefore, when the operating command including information on the target outlet water temperature instructed from the control panel does not fall within an operational temperature range of the chillers, this prevents the chillers from being operated in accordance with the operating command.

The present invention has been made in view of the above circumstances, and it is an object of the present disclosure to provide a chiller system in which a chiller can supply water at a target outlet water temperature, and an air-conditioning apparatus including the chiller system.

According to the present invention the above objective is solved by a chiller system having the features of claim <NUM>.

In the chiller system according to one embodiment of the present invention, the second controller can obtain a temperature range that is operational for the chiller from the first controller. Therefore, the second controller can output an appropriate operating command in response to the temperature range that is operational for the chiller. This allows the chiller to supply water at a target outlet water temperature that is set within the operational temperature range in accordance with the operating command.

Hereinafter, a chiller system according to an embodiment will be described with reference to the drawings. Note that the same constituent elements in the drawings are denoted by the same reference numerals, and redundant explanation will be omitted appropriately.

<FIG> illustrates the configuration of a chiller system A in an air-conditioning apparatus according to Embodiment <NUM>.

Note that a chiller 1_1, a chiller 1_2, and a chiller 1_3 are also referred to as "chiller <NUM>" when it is not necessary to distinguish between them. The same applies to other constituent elements.

As illustrated in <FIG>, the chiller system A includes the chiller 1_1, the chiller 1_2, and the chiller 1_3. The chiller 1_1, the chiller 1_2, and the chiller 1_3 are provided in an outdoor unit <NUM> of the air-conditioning apparatus. A load <NUM>, a second controller <NUM>, a water temperature sensor <NUM>, and a water delivery pump <NUM> are provided in an indoor unit <NUM>.

The chiller 1_1, the chiller 1_2, and the chiller 1_3 cool or heat input water, and output and circulate the cooled or heated water. Note that the water may be antifreeze. In Embodiment <NUM>, while three units of chillers 1_1, 1_2, and 1_3 are illustrated, it suffices that the number of chillers <NUM> is equal to or larger than one.

For example, a heat exchanger in the air-conditioning apparatus is used for a heat source of the chiller 1_1, the chiller 1_2, and the chiller 1_3. Specifically, a heat <NUM> pump is used as the heat source, and water in the chiller system A exchanges heat with refrigerant flowing through the heat exchanger in the air-conditioning apparatus.

The chiller 1_1 is provided with a first sensor IS_1 configured to measure the inlet water temperature of the chiller 1_1. The chiller 1_2 is provided with a first sensor IS_2 configured to measure the inlet water temperature of the chiller 1_2. The chiller 1_3 is provided with a first sensor IS_3 configured to measure the inlet water temperature of the chiller 1_3.

The chiller 1_1 is provided with a second sensor OS_1 configured to measure the inlet water temperature of the chiller 1_1. The chiller 1_2 is provided with a second sensor OS_2 configured to measure the inlet water temperature of the chiller 1_2. The chiller 1_3 is provided with a second sensor OS_3 configured to measure the inlet water temperature of the chiller 1_3.

Outside the chiller 1_1, a third sensor S_1 configured to measure the outside air temperature of the chiller 1_1 is provided. Outside the chiller 1_2, a third sensor S_2 configured to measure the outside air temperature of the chiller 1_2 is provided. Outside the chiller 1_3, a third sensor S_2 configured to measure the outside air temperature of the chiller 1_3 is provided.

The chiller 1_1 includes a first controller C_1. The first controller C_1 controls the chiller 1_1 in its entirety. The first controller C_1 calculates a first temperature range that is operational for the chiller 1_1 based on the inlet water temperature measured by the first sensor IS_1, the outlet water temperature measured by the second sensor OS_1, and the outside air temperature measured by the third sensor S_1. The first controller C_1 transmits information on the first temperature range to the second controller <NUM>. The chiller 1_2 includes a first controller C_2. The first controller C_2 controls the chiller 1_2 in its entirety. The first controller C_2 calculates a second temperature range that is operational for the chiller 1_1 based on the inlet water temperature measured by the first sensor IS_2, the outlet water temperature measured by the second sensor OS_2, and the outside air temperature measured by the third sensor S_2. The first controller C_2 transmits information on the second temperature range to the second controller <NUM>. The chiller 1_3 includes a first controller C_3. The first controller C_3 controls the chiller 1_3 in its entirety. The first controller C_3 calculates a third temperature range that is operational for the chiller 1_3 based on the inlet water temperature measured by the first sensor IS_3, the outlet water temperature measured by the second sensor OS_3, and the outside air temperature measured by the third sensor S_3. The first controller C_3 transmits information on the third temperature range to the second controller <NUM>.

The temperature range is calculated by the first controller C by using, for example, a table that defines the relationship between the temperature range and the inlet water temperature, outlet water temperature, and outside air temperature of the chiller <NUM>.

Note that the first controller C_1, the first controller C_2, and the first controller C_3 in the chiller <NUM> may be a controller of the air-conditioning apparatus. The first controller C_1, the first controller C_2, and the first controller C_3 may communicate with the second controller <NUM> either through a wire or wireless communication.

The first controller C is made up of dedicated hardware or a central processing unit (CPU, also referred to as "processing device," "computation device," "microprocessor," "microcomputer," or "processor") configured to execute programs stored in a memory. When the first controller C is dedicated hardware, the first controller C is equivalent to, for example, a single circuit, a combined circuit, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or a combination thereof. The functional units of the first controller C may be individually implemented by separate units of hardware, or the functional units of the first controller C may be implemented together by a single unit of hardware. When the first controller C is a CPU, the functions to be executed by the first controller C are implemented by software, firmware, or a combination of the software and the firmware. The software and the firmware are described as programs and stored in the memory. The CPU reads and executes the programs stored in the memory, thereby to implement the functions of the first controller C. For example, the memory is a nonvolatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM. Note that the functions of the first controller C may be partially implemented by dedicated hardware, while being partially implemented by software or firmware.

The chiller 1_1 and the load <NUM> are connected by a feed pipe <NUM> and a return pipe <NUM> in which heated or cooled water flows.

The feed pipe <NUM> branches off into a feed pipe 3_1, a feed pipe 3_2, and a feed pipe 3_3 near the chiller <NUM>. The chiller 1_1 is connected to the feed pipe 3_1 of the feed pipe <NUM>. The chiller 1_2 is connected to the feed pipe 3_2 of the feed pipe <NUM>. The chiller 1_3 is connected to the feed pipe 3_3 of the feed pipe <NUM>.

The return pipe <NUM> branches off into a return pipe 4_1, a return pipe 4_2, and a return pipe 4_3. The chiller 1_1 is connected to the return pipe 4_1 of the return pipe <NUM>. The chiller 1_2 is connected to the return pipe 4_2 of the return pipe <NUM>. The chiller 1_3 is connected to the return pipe 4_3 of the return pipe <NUM>.

The load <NUM> is connected to the feed pipe <NUM> and the return pipe <NUM>. The load <NUM> refers to some of the components of the indoor unit <NUM> in the air-conditioning apparatus, such as a fan coil unit. The load <NUM> is not limited to being a component of the air-conditioning apparatus.

The feed pipe <NUM> is provided with the water temperature sensor <NUM>. The water temperature sensor <NUM> is provided on the feed pipe <NUM> in the vicinity of the load <NUM>. The water temperature sensor <NUM> measures the temperature of water flowing in the feed pipe <NUM> to be input to the load <NUM>, and outputs information on the measured temperature to the second controller <NUM>.

The return pipe <NUM> is provided with the water delivery pump <NUM>. The water delivery pump <NUM> delivers water flowing through the return pipe <NUM> from the load <NUM> to the chiller <NUM>. The water delivery pump <NUM> adjusts the water flow rate of water flowing through the return pipe <NUM> based on a first operating command including information on the water flow rate and output from the second controller <NUM>. Note that the water delivery pump <NUM> may be provided on the feed pipe <NUM>.

The second controller <NUM> is provided on a control board of the load <NUM> in the indoor unit <NUM>. The second controller <NUM> calculates a water flow rate at which water is discharged from the water delivery pump <NUM> based on information on the first temperature range output from the first controller C_1, the second temperature range output from the first controller C_2, and the third temperature range output from the first controller C_3. The second controller <NUM> outputs the first operating command including information on the calculated water flow rate to the water delivery pump <NUM>. Accordingly, the water delivery pump <NUM> delivers water at the water flow rate instructed by the first operating command. That is, the second controller <NUM> controls the flow rate of water flowing through the feed pipe <NUM> and the return pipe <NUM> by outputting the first operating command.

The water flow rate for the water delivery pump <NUM> controlled by the second controller <NUM> is calculated by, for example, using a table that defines the relationship between the water flow rate for the water delivery pump <NUM> and the first, second, and third temperature ranges.

The second controller <NUM> receives information on a target outlet water temperature of the chiller 1_1, a target outlet water temperature of the chiller 1_2, and a target outlet water temperature of the chiller 1_3. The second controller <NUM> may receive information on the target outlet water temperatures constantly or regularly.

Based on information on the temperature of water flowing in the feed pipe <NUM> measured by the water temperature sensor <NUM>,
the temperature range output from the first controller C, and the target outlet water temperature of the chiller <NUM> output from the first controller C, the second controller <NUM> outputs an operating command to control the chiller <NUM>.

Specifically, the second controller <NUM> outputs a chiller operating command to the first controller C_1 based on the water temperature measured by the water temperature sensor <NUM> and the target outlet water temperature of the chiller 1_1. The second controller <NUM> outputs a chiller operating command to the first controller C_2 based on the water temperature measured by the water temperature sensor <NUM> and the target outlet water temperature of the chiller 1_2. The second controller <NUM> outputs a chiller operating command to the first controller C_3 based on the water temperature measured by the water temperature sensor <NUM> and the target outlet water temperature of the chiller 1_3.

The second controller <NUM> compares the water temperature measured by the water temperature sensor <NUM> with the target outlet water temperature designated to the chiller 1_1. When the water temperature measured by the water temperature sensor <NUM> does not reach the target outlet water temperature, the second controller <NUM> determines whether the target outlet water temperature falls within the temperature range of the chiller 1_1. When the target outlet water temperature falls within the temperature range of the chiller 1_1, the second controller <NUM> outputs a chiller operating command to the chiller 1_1, including information on continuation of operation or the target outlet water temperature. When receiving the chiller operating command, the chiller 1_1 continues operation or operates in such a manner that the outlet water temperature of the chiller 1_1 becomes the target outlet water temperature. When the target outlet water temperature falls outside the temperature range of the chiller 1_1, the operating capacity of the chiller 1_1 is either excessive or insufficient. Accordingly, the second controller <NUM> outputs a chiller operating command to control the heat source of the outdoor unit <NUM> and the water delivery pump <NUM> to the chiller 1_1.

For example, when the capacity of the chiller 1_1 is insufficient, the second controller <NUM> outputs a chiller operating command to the chiller 1_1 to execute such a control as to decrease the frequency of the water delivery pump <NUM> in the chiller system A and maximize the frequency of a compressor in the outdoor unit <NUM>. When the capacity of the chiller 1_1 is excessive, the second controller <NUM> outputs a chiller operating command to the chiller 1_1 to execute such a control as to increase the frequency of the water delivery pump <NUM> in the chiller system A and minimize the frequency of the compressor in the outdoor unit <NUM>. When the water temperature measured by the water temperature sensor <NUM> is the target outlet water temperature, the second controller <NUM> outputs a chiller operating command including an operation stop command to the chiller 1_1. When receiving the chiller operating command including an operation stop command, the chiller 1_1 stops operation.

Specifically, the second controller <NUM> compares the water temperature measured by the water temperature sensor <NUM> with the target outlet water temperature designated to the chiller 1_2. When the water temperature measured by the water temperature sensor <NUM> does not reach the target outlet water temperature, the second controller <NUM> determines whether the target outlet water temperature falls within the temperature range of the chiller 1_2. When the target outlet water temperature falls within the temperature range of the chiller 1_2, the second controller <NUM> outputs a chiller operating command to the chiller 1_2, including information on continuation of operation or the target outlet water temperature. When receiving the chiller operating command, the chiller 1_2 continues operation or operates in such a manner that the outlet water temperature of the chiller 1_2 becomes the target outlet water temperature. When the target outlet water temperature falls outside the temperature range of the chiller 1_2, the operating capacity of the chiller 1_2 is either excessive or insufficient. Accordingly, the second controller <NUM> outputs a chiller operating command to control the heat source of the outdoor unit <NUM> and the water delivery pump <NUM> to the chiller 1_2.

For example, when the capacity of the chiller 1_2 is insufficient, the second controller <NUM> outputs a chiller operating command to the chiller 1_2 to execute such a control as to decrease the frequency of the water delivery pump <NUM> in the chiller system A and maximize the frequency of the compressor in the outdoor unit <NUM>. When the capacity of the chiller 1_2 is excessive, the second controller <NUM> outputs a chiller operating command to the chiller 1_2 to execute such a control as to increase the frequency of the water delivery pump <NUM> in the chiller system A and minimize the frequency of the compressor in the outdoor unit <NUM>. When the water temperature measured by the water temperature sensor <NUM> is the target outlet water temperature, the second controller <NUM> outputs a chiller operating command including an operation stop command to the chiller 1_2. When receiving the chiller operating command including an operation stop command, the chiller 1_2 stops operation.

The second controller <NUM> compares the water temperature measured by the water temperature sensor <NUM> with the target outlet water temperature designated to the chiller 1_3. When the water temperature measured by the water temperature sensor <NUM> does not reach the target outlet water temperature, the second controller <NUM> determines whether the target outlet water temperature falls within the temperature range of the chiller 1_3. When the target outlet water temperature falls within the temperature range of the chiller 1_3, the second controller <NUM> outputs a chiller operating command to the chiller 1_3, including information on continuation of operation or the target outlet water temperature. When receiving the chiller operating command, the chiller 1_3 continues operation or operates in such a manner that the outlet water temperature of the chiller 1_3 becomes the target outlet water temperature. When the target outlet water temperature falls outside the temperature range of the chiller 1_3, the operating capacity of the chiller 1_3 is either excessive or insufficient. Accordingly, the second controller <NUM> outputs a chiller operating command to control the heat source of the outdoor unit <NUM> and the water delivery pump <NUM> to the chiller 1_3.

For example, when the capacity of the chiller 1_3 is insufficient, the second controller <NUM> outputs a chiller operating command to the chiller 1_3 to execute such a control as to decrease the frequency of the water delivery pump <NUM> in the chiller system A and maximize the frequency of the compressor in the outdoor unit <NUM>. When the capacity of the chiller 1_3 is excessive, the second controller <NUM> outputs a chiller operating command to the chiller 1_3 to execute such a control as to increase the frequency of the water delivery pump <NUM> in the chiller system A and minimize the frequency of the compressor in the outdoor unit <NUM>. When the water temperature measured by the water temperature sensor <NUM> is the target outlet water temperature, the second controller <NUM> outputs a chiller operating command including an operation stop command to the chiller 1_3. When receiving the chiller operating command including an operation stop command, the chiller 1_3 stops operation.

The second controller <NUM> is made up of dedicated hardware or a central processing unit (CPU, also referred to as "processing device," "computation device," "microprocessor," "microcomputer," or "processor") configured to execute programs stored in a memory. When the second controller <NUM> is dedicated hardware, the second controller <NUM> is equivalent to, for example, a single circuit, a combined circuit, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or a combination thereof. The functional units of the second controller <NUM> may be individually implemented by separate units of hardware, or the functional units of the second controller <NUM> may be implemented together by a single unit of hardware. When the second controller <NUM> is a CPU, the functions to be executed by the second controller <NUM> are implemented by software, firmware, or a combination of the software and the firmware. The software and the firmware are described as programs and stored in the memory. The CPU reads and executes the programs stored in the memory, thereby to implement the functions of the second controller <NUM>. For example, the memory is a nonvolatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM. Note that the functions of the second controller <NUM> may be partially implemented by dedicated hardware, while being partially implemented by software or firmware.

<FIG> is a functional block diagram of the chiller <NUM> in the air-conditioning apparatus according to Embodiment <NUM>.

As illustrated in <FIG>, the chiller <NUM> includes a temperature-range calculation unit <NUM>. The temperature-range calculation unit <NUM> includes a request detection unit <NUM>.

The temperature-range calculation unit <NUM> calculates an operational temperature range of the chiller <NUM> based on the inlet water temperature measured by the first sensor IS, the outlet water temperature measured by the second sensor OS, and the outside air temperature measured by the third sensor S, and then outputs information on the calculated temperature range to the second controller <NUM>.

Specifically, the temperature-range calculation unit <NUM> calculates an operational temperature range of the chiller 1_1 based on the inlet water temperature measured by the first sensor IS_1, the outlet water temperature measured by the second sensor OS_1, and the outside air temperature measured by the third sensor S_1. Then, the temperature-range calculation unit <NUM> outputs information on the calculated operational temperature range of the chiller 1_1 to the second controller <NUM>. The temperature-range calculation unit <NUM> calculates an operational temperature range of the chiller 1_2 based on the inlet water temperature measured by the first sensor IS_2, the outlet water temperature measured by the second sensor OS_2, and the outside air temperature measured by the third sensor S_2. Then, the temperature-range calculation unit <NUM> outputs information on the calculated operational temperature range of the chiller 1_2 to the second controller <NUM>. The temperature-range calculation unit <NUM> calculates an operational temperature range of the chiller 1_3 based on the inlet water temperature measured by the first sensor IS_3, the outlet water temperature measured by the second sensor OS_3, and the outside air temperature measured by the third sensor S_3. Then, the temperature-range calculation unit <NUM> outputs information on the calculated operational temperature range of the chiller 1_3 to the second controller <NUM>.

The request detection unit <NUM> is connected to the second controller <NUM> through wired communication or wireless communication, and detects a request for calculation of a temperature range transmitted from the second controller <NUM>.

When the request detection unit <NUM> detects the request, the temperature-range calculation unit <NUM> calculates a temperature range of the chiller <NUM>.

<FIG> is a functional block diagram of the second controller <NUM> in the air-conditioning apparatus according to Embodiment <NUM>.

As illustrated in <FIG>, the second controller <NUM> includes an operating command unit <NUM>. The operating command unit <NUM> incudes a water-flow calculation unit <NUM>.

The water-flow calculation unit <NUM> calculates a water flow rate for the water delivery pump <NUM> based on information on the first temperature range output from the first controller C1_1, the second temperature range output from the first controller C_2, and the third temperature range output from the first controller C_3. The water-flow calculation unit <NUM> outputs a first operating command including information on the calculated water flow rate to the water delivery pump <NUM>.

The operating command unit <NUM> outputs a chiller operating command to the chiller <NUM> based on information on the temperature range received from the first controller C, the water temperature measured by the water temperature sensor <NUM>, and the target outlet water temperature of the chiller <NUM>.

Specifically, the operating command unit <NUM> outputs a chiller operating command to the chiller <NUM> based on information on the temperature range received from the first controller C_1, the water temperature measured by the water temperature sensor <NUM>, and the target outlet water temperature of the chiller 1_1. The operating command unit <NUM> outputs a chiller operating command to the chiller <NUM> based on information on the temperature range received from the first controller C_2, the water temperature measured by the water temperature sensor <NUM>, and the target outlet water temperature of the chiller 1_2. The operating command unit <NUM> outputs a chiller operating command to the chiller <NUM> based on information on the temperature range received from the first controller C_3, the water temperature measured by the water temperature sensor <NUM>, and the target outlet water temperature of the chiller 1_3.

Next, operation of the chiller system A in the air-conditioning apparatus according to Embodiment <NUM> is described.

In <FIG>, water flowing out from the chiller 1_1 flows through the feed pipe 3_1. Water flowing out from the chiller 1_2 flows through the feed pipe 3_2. Water flowing out from the chiller 1_3 flows through the feed pipe 3_3. The flows of water through the feed pipe 3_1, the feed pipe 3_2, and the feed pipe 3_3 merge together at the feed pipe <NUM>.

The water flowing through the feed pipe <NUM> exchanges heat with the load <NUM>, and cools or heats the load <NUM>.

The water having exchanged heat with the load <NUM> flows through the return pipe <NUM>. The flow of water through the return pipe <NUM> then branches off into the return pipe 4_1, the return pipe 4_2, and the return pipe 4_3.

Water flowing through the return pipe 4_1 is input to the chiller 1_1. Water flowing through the return pipe 4_2 is input to the chiller 1_2. Water flowing through the return pipe 4_3 is input to the chiller 1_3. In this manner, water circulates between the chiller 1_1 and the load <NUM>, between the chiller 1_2 and the load <NUM>, and between the chiller 1_3 and the load <NUM>.

<FIG> is a flowchart for describing operation of the chiller <NUM> in the air-conditioning apparatus according to Embodiment <NUM>.

As illustrated in <FIG>, the first controller C in the chiller <NUM> determines whether an operation power supply of the chiller <NUM> is turned on (step S1). In step S1, when determining that the operation power supply of the chiller <NUM> is not turned on (NO in step S1), the first controller C continuously performs the determination in step S1. In step S1, when the first controller C determines that the operation power supply of the chiller <NUM> is turned on (YES in step S1), the chiller <NUM> starts operating at an initial frequency (step S2). For example, the initial frequency refers to a frequency of a compressor in an outdoor unit when the chiller system A is included in an air-conditioning apparatus <NUM>.

Next, the first controller C determines whether the chiller <NUM> has received a chiller operating command from the second controller <NUM> (step S3). In step S3, when the first controller C determines that the chiller <NUM> does not receive a chiller operating command from the second controller <NUM> (NO in step S3), the first controller C returns to the process in step S2. In step S3, when the first controller C determines that the chiller <NUM> has received a chiller operating command from the second controller <NUM> (YES in step S3), the first controller C controls the frequency of the compressor in the outdoor unit <NUM> and the frequency of the water delivery pump <NUM> in accordance with the chiller operating command (step S4).

Next, the first controller C calculates an operational temperature range of the chiller <NUM>, then outputs information on the calculated operational temperature range of the chiller <NUM> to the second controller <NUM> (step S5), and returns to the process in step S1.

Next, the method for calculating a temperature range in step S5 of <FIG> is described. <FIG> is a flowchart for describing an output of information on the temperature range from the first controller C in the air-conditioning apparatus according to Embodiment <NUM>. <FIG> is an explanatory diagram for describing step S5 of <FIG> in detail.

As illustrated in <FIG>, the first controller C determines whether a request from the second controller <NUM> for calculation of the temperature range has been detected (step S5_1). In step S5_1, when the request for calculation of the temperature range is not detected (NO in step S5_1), the first controller C continuously performs the determination in step S5_1. In step S1, when determining that the request for calculation of the temperature range has been detected (YES in step S5_1), the first controller C shifts to the process in step S5_2.

The first controller C receives information on the inlet water temperature, the outlet water temperature, and the outside air temperature of the chiller <NUM> (step S5_2). That is, the first controller C_1 receives information on the inlet water temperature measured by the first sensor IS_1, the outlet water temperature measured by the second sensor OS_1, and the outside air temperature measured by the third sensor S_1. The first controller C_2 receives information on the inlet water temperature measured by the first sensor IS_2, the outlet water temperature measured by the second sensor OS_2, and the outside air temperature measured by the third sensor S_2. The first controller C_3 receives information on the inlet water temperature measured by the first sensor IS_3, the outlet water temperature measured by the second sensor OS_3, and the outside air temperature measured by the third sensor S_3.

Next, the first controller C calculates an operational temperature range of the chiller <NUM> based on the inlet water temperature, the outlet water temperature, and the outside air temperature of the chiller <NUM> (step S5_3), then outputs information on the calculated temperature range to the second controller <NUM> (step S5_4), and returns to the process in step S1.

That is, the first controller C_1 calculates an operational temperature range of the chiller 1_1 based on the inlet water temperature, outlet water temperature, and outside air temperature of the chiller 1_1, and outputs information on the calculated temperature range of the chiller 1_1 to the second controller <NUM>. The first controller C_2 calculates an operational temperature range of the chiller 1_2 based on the inlet water temperature, outlet water temperature, and outside air temperature of the chiller 1_2, and outputs information on the calculated temperature range of the chiller 1_2 to the second controller <NUM>. The first controller C_3 calculates an operational temperature range of the chiller 1_3 based on the inlet water temperature, outlet water temperature, and outside air temperature of the chiller 1_3, and outputs information on the calculated temperature range of the chiller 1_3 to the second controller <NUM>.

<FIG> is a flowchart for describing operation of the second controller <NUM> in the air-conditioning apparatus according to Embodiment <NUM>.

As illustrated in <FIG>, upon the start of operation, the second controller <NUM> turns the water delivery pump <NUM> on (step S11). Next, the second controller <NUM> determines whether the temperature of water flowing through the feed pipe <NUM> and the return pipe <NUM> has decreased (step S12).

In this determination of whether the water temperature has decreased, for example, when receiving a signal indicating a decrease in the water temperature from the load <NUM>, the second controller <NUM> determines that the water temperature has decreased. The signal indicating a decrease in the water temperature is output from the load <NUM> to the second controller <NUM> when the temperature of water circulating to the load <NUM> is lower than a target temperature of water circulating to the load <NUM>. The determination of whether the water temperature has decreased is not limited to being performed by this method. The second controller <NUM> may determine whether the water temperature has decreased based on the water temperature measured by the water temperature sensor <NUM>.

When determining that the water temperature does not decrease (NO in step S12), the second controller <NUM> continuously performs the determination in step S12. When determining that the water temperature has decreased (YES in step S12), the second controller <NUM> receives information on a temperature range transmitted from each of the chiller 1_1, the chiller 1_2, and the chiller 1_3 (step S13).

Next, the second controller <NUM> calculates a water flow rate for the water delivery pump <NUM> based on information on the temperature range output from each of the chiller 1_1, the chiller 1_2, and the chiller 1_3 (step S14).

Then, the second controller <NUM> outputs a first operating command including information on the water flow rate calculated in step S14 to the water delivery pump <NUM> (step S15).

Next, the second controller <NUM> outputs a chiller operating command to each of the chiller 1_1, the chiller 1_2, and the chiller 1_3 based on information on the water temperature measured by the water temperature sensor <NUM> and the temperature range output from each of the chiller 1_1, the chiller 1_2, and the chiller 1_3 (step S16).

In Embodiment <NUM>, the first controller C has been described as calculating a temperature range and outputting information on the calculated temperature range to the second controller <NUM> upon request for calculation of the temperature range from the second controller <NUM>. In a modification of Embodiment <NUM>, the first controller C constantly outputs information on the temperature range to the second controller <NUM>.

<FIG> is a flowchart for describing a modification of the operation of the first controller C in the air-conditioning apparatus according to Embodiment <NUM>. Note that the same steps as those in <FIG> are denoted by the same reference numerals, and descriptions thereof are omitted. As illustrated in <FIG>, compared to <FIG>, the process in step S5 is eliminated, and even when there is not a request for the temperature range from the second controller <NUM>, the first controller C still outputs information on the temperature range to the second controller <NUM>.

In the chiller system A in the air-conditioning apparatus according to Embodiment <NUM>, the second controller <NUM> controls the water flow rate of water flowing through the feed pipe <NUM> and the return pipe <NUM>, such that information on the water temperature falls within the temperature range output from the temperature-range calculation unit <NUM> in the first controller C. Therefore, the chiller <NUM> can supply water at its target outlet water temperature.

In a conventional chiller system, since the second controller <NUM> does not receive information on the operational temperature range, the second controller <NUM> cannot determine whether the chiller operating command satisfies the operational temperature range of the chiller <NUM>. If in this state, the second controller <NUM> outputs the chiller operating command to the chiller <NUM>, then there is a possibility that the output chiller operating command may fall outside the operational temperature range of the chiller <NUM>.

For example, when the second controller <NUM> instructs the chiller <NUM> to reduce its heating capacity in heating operation, to avoid a decrease in the outlet water temperature of the chiller <NUM>, the second controller <NUM> controls pump operation to reduce the water flow rate with the outlet and inlet water temperatures of the chiller <NUM> maintained, thereby to reduce the capacity of the chiller <NUM>. When receiving a chiller operating command equal to or lower than the operating range, the chiller <NUM> is operated at a lower limit of the operational temperature range, and thus decreases the water flow rate since it cannot reduce the capacity any more. As the water flow rate decreases, the difference between the outlet water temperature and the inlet water temperature increases. The capacity is calculated as "capacity = coefficient × difference between outlet water temperature and inlet water temperature × water flow rate. " In heating operation, as the outlet water temperature increases, the operation becomes inefficient. Conversely, during cooling, as the outlet water temperature decreases, there is a risk of water freezing or other problem.

Therefore, in a case where the second controller <NUM> does not acquire information on the operational temperature range of the chiller <NUM>, the second controller <NUM> does not have information for determining whether and how to change the water flow rate for the water delivery pump <NUM>. This prevents the chiller system from operating efficiently. In a case where the second controller <NUM> attempts to cause the chiller <NUM> to operate at a capacity equal to or greater than the upper limit of the operational temperature range of the chiller <NUM>, the capacity of the chiller <NUM> is insufficient for the operating command from the second controller <NUM>. This prevents the chiller <NUM> from supplying water at a requested water temperature.

In the chiller system A in the air-conditioning apparatus in Embodiment <NUM>, the chiller <NUM> inputs information on its operational temperature range to the second controller <NUM>, so that the second controller <NUM> can select operation with an optimum target outlet water temperature and an optimum water flow rate from the operational temperature range of the chiller <NUM>. Therefore, the chiller <NUM> supplies water at a stabilized temperature, which makes it possible for the chiller <NUM> and the water delivery pump <NUM> to operate with high efficiency in their entirety.

Next, the chiller system A in the air-conditioning apparatus according to Embodiment <NUM> is described.

<FIG> illustrates the configuration of the chiller system A in the air-conditioning apparatus according to Embodiment <NUM>. Note that the same components as those in <FIG> are denoted by the same reference numerals, and mainly different components will be described.

As illustrated in <FIG>, the chiller system A in the air-conditioning apparatus according to Embodiment <NUM> is provided with a water-water heat exchanger <NUM> between the chiller <NUM> and the load <NUM>. In <FIG>, the feed pipe <NUM> and the return pipe <NUM> that are located near the chiller 1_1, the chiller 1_2, and the chiller 1_3 are defined as a primary-side feed pipe and a primary-side return pipe, while a feed pipe <NUM> and a return pipe <NUM> that are located near the load <NUM> are defined as a secondary-side feed pipe and a secondary-side return pipe.

The primary-side feed pipe <NUM> connects the chiller <NUM> and the water-water heat exchanger <NUM>. The primary-side return pipe <NUM> connects the chiller <NUM> and the water-water heat exchanger <NUM>. The feed pipe <NUM> is connected to the return pipe <NUM> in the water-water heat exchanger <NUM>. Water flows through the feed pipe <NUM> and the return pipe <NUM> to circulate between the chiller <NUM> and the water-water heat exchanger <NUM>.

The secondary-side feed pipe <NUM> connects the load <NUM> and the water-water heat exchanger <NUM>. The secondary-side return pipe <NUM> connects the load <NUM> and the water-water heat exchanger <NUM>. The feed pipe <NUM> is connected to the return pipe <NUM> in the water-water heat exchanger <NUM>. Water flows through the feed pipe <NUM> and the return pipe <NUM> to circulate between the load <NUM> and the water-water heat exchanger <NUM>.

The water-water heat exchanger <NUM> exchanges heat between water flowing through the feed pipe <NUM> and the return pipe <NUM> and water flowing through the feed pipe <NUM> and the return pipe <NUM>.

The feed pipe <NUM> is provided with a water temperature sensor 6_1. The water temperature sensor 6_1 is provided on the feed pipe <NUM> in the vicinity of the load <NUM>. The water temperature sensor 6_1 measures the temperature of water flowing through the feed pipe <NUM> to be input to the load <NUM>, and outputs information on the measured temperature to the second controller <NUM>.

The return pipe <NUM> is provided with a secondary-side water delivery pump 7_1. The water delivery pump 7_1 delivers water flowing through the return pipe <NUM> from the load <NUM> to the water-water heat exchanger <NUM>. The water delivery pump 7_1 adjusts the water flow rate of water flowing through the return pipe <NUM> based on a second operating command including information on the water flow rate output from the second controller <NUM>.

The second controller <NUM> calculates a water flow rate for the water delivery pump 7_1 based on information on the first temperature range output from the first controller C_1, the second temperature range output from the first controller C_2, and the third temperature range output from the first controller C_3. The second controller <NUM> outputs a second operating command including information on the calculated water flow rate to the water delivery pump 7_1. Accordingly, the water delivery pump 7_1 delivers water at the water flow rate instructed by the second operating command. That is, the second operating command is a command for water flowing through the feed pipe <NUM> and the return pipe <NUM>.

At the water flow rate for the secondary-side water delivery pump 7_1, the primary-side capacity and the secondary-side capacity become equal. The primary-side capacity is calculated as "water temperature difference between the inlet temperature of water flowing through the feed pipe <NUM> and the outlet temperature of water flowing through the return pipe <NUM> × primary-side water flow rate × coefficient. " The secondary-side capacity is calculated as "water temperature difference between the inlet temperature of water flowing through the feed pipe <NUM> and the outlet temperature of water flowing through the return pipe <NUM> × secondary-side water flow rate × coefficient.

<FIG> is a functional block diagram of the second controller <NUM> in the air-conditioning apparatus according to Embodiment <NUM>. Note that the same components as those in <FIG> are denoted by the same reference numerals, and mainly different components will be described.

As illustrated in <FIG>, the operating command unit <NUM> in Embodiment <NUM> includes a secondary-side water-flow calculation unit <NUM> in addition to the water-flow calculation unit <NUM>.

The secondary-side water-flow calculation unit <NUM> calculates a water flow rate for the secondary-side water delivery pump 7_1 based on information on the first temperature range output from the first controller C1_1, the second temperature range output from the first controller C_2, and the third temperature range output from the first controller C_3. The secondary-side water-flow calculation unit <NUM> outputs a second operating command including information on the calculated water flow rate to the secondary-side water delivery pump 7_1.

<FIG> is a flowchart for describing a flow of output of the second operating command from the second controller <NUM> in the chiller system A in the air-conditioning apparatus according to Embodiment <NUM>. Note that the same portions as those in <FIG> are denoted by the same reference numerals, and different portions are now described.

After the process in step S17, the second controller <NUM> calculates a water flow rate for the secondary-side water delivery pump 7_1 based on information on the temperature range output from each of the chiller 1_1, the chiller 1_2, and the chiller 1_3 (step S18).

Next, the second controller <NUM> outputs the second operating command including information on the water flow rate calculated in step S18 to the secondary-side water delivery pump 7_1 (step S19), and then returns to the process in step S13.

In the chiller system A in the air-conditioning apparatus according to Embodiment <NUM>, the water-water heat exchanger <NUM> exchanges heat between water flowing through the primary-side feed pipe <NUM> and return pipe <NUM> and water flowing through the secondary-side feed pipe <NUM> and return pipe <NUM>. Therefore, when the primary-side water quality becomes degraded, a secondary-side load <NUM> can be prevented from being supplied with the water of degraded quality.

Next, the air-conditioning apparatus according to Embodiment <NUM> is described. The air-conditioning apparatus according to Embodiment <NUM> includes the chiller system A in Embodiment <NUM> or the chiller system A in Embodiment <NUM>.

<FIG> illustrates an example of a refrigerant circuit diagram of the air-conditioning apparatus <NUM> according to Embodiment <NUM>. Note that the solid arrows illustrated in <FIG> show the refrigerant flow direction during cooling operation. Further, the dotted arrows illustrated in <FIG> show the refrigerant flow direction during heating operation.

The air-conditioning apparatus <NUM> according to the embodiment includes the indoor unit <NUM> and the outdoor unit <NUM>. The indoor unit <NUM> and the outdoor unit <NUM> are connected by a refrigerant pipe <NUM>. The indoor unit <NUM> includes an indoor heat exchanger <NUM>. The outdoor unit <NUM> includes a compressor <NUM>, a four-way valve <NUM>, an outdoor heat exchanger <NUM>, and an expansion valve <NUM>.

The compressor <NUM> compresses suctioned refrigerant and discharges the compressed refrigerant. Although not particularly limited, the compressor <NUM> may include, for example, an inverter circuit or other circuit that optionally changes the operating frequency, thereby to change the capacity of the compressor <NUM>. Note that the capacity of the compressor <NUM> represents the amount of refrigerant to be delivered per unit time. The four-way valve <NUM> is, for example, a switching valve to switch between the refrigerant flow direction for cooling operation and the refrigerant flow direction for heating operation.

The outdoor heat exchanger <NUM> exchanges heat between refrigerant and outside air. The outdoor heat exchanger <NUM> serves as an evaporator during heating operation to evaporate and vaporize the refrigerant. The outdoor heat exchanger <NUM> serves as a condenser during cooling operation to condense and liquefy the refrigerant.

The expansion valve <NUM> reduces the pressure of refrigerant and expands the refrigerant. For example, in a case where the expansion valve <NUM> is made up of an electronic expansion valve, the opening degree of the expansion valve <NUM> is adjusted based on an instruction provided by a controller or other device (not illustrated). The indoor heat exchanger <NUM> exchanges heat between refrigerant and air in an air-conditioning target space. The indoor heat exchanger <NUM> serves as a condenser during heating operation to condense and liquefy the refrigerant. The indoor heat exchanger <NUM> serves as an evaporator during cooling operation to evaporate and vaporize the refrigerant.

The air-conditioning apparatus <NUM> having the configuration as described above can perform heating operation and cooling operation by changing the refrigerant flow direction through the four-way valve <NUM> in the outdoor unit <NUM>.

Claim 1:
A chiller system (A) comprising:
a chiller (<NUM>, 1_1, 1_2, 1_3) configured to output water at an adjusted temperature;
a load (<NUM>) of the chiller (<NUM>, 1_1, 1_2, 1_3);
a feed pipe (<NUM>, 3_1, 3_2, 3_3, <NUM>) through which water flows to be supplied from the chiller (<NUM>, 1_1, 1_2, 1_3) to the load (<NUM>), the feed pipe (<NUM>, 3_1, 3_2, 3_3, <NUM>) being connected between the chiller (<NUM>, 1_1, 1_2, 1_3) and the load (<NUM>);
a return pipe (<NUM>, 4_1, 4_2, 4_3, <NUM>) through which water flows back to the chiller (<NUM>, 1_1, 1_2, 1_3) from the load (<NUM>), the return pipe (<NUM>, 4_1, 4_2, 4_3, <NUM>) being connected between the chiller (<NUM>, 1_1, 1_2, 1_3) and the load (<NUM>);
a first controller (C, C_1, C_2, C_3) configured to control the chiller (<NUM>, 1_1, 1_2, 1_3); and
a second controller (<NUM>) configured to output a chiller operating command to control the chiller (<NUM>, 1_1, 1_2, 1_3) to the first controller (C, C_1, C_2, C_3), wherein
the chiller (<NUM>, 1_1, 1_2, 1_3) includes
a first sensor (IS, IS_1, IS_2, IS_3) configured to measure an inlet water temperature of the water flowing through the return pipe (<NUM>, 4_1, 4_2, 4_3, <NUM>) to the chiller (<NUM>, 1_1, 1_2, 1_3),
a second sensor (OS, OS_1, OS_2, OS_3) configured to measure an outlet water temperature of the water flowing through the feed pipe (<NUM>, 3_1, 3_2, 3_3, <NUM>) from the chiller (<NUM>, 1_1, 1_2, 1_3), and
a third sensor (S, S_1, S_2, S_3) configured to measure an outside air temperature at a location where the chiller (<NUM>, 1_1, 1_2, 1_3) is installed, and characterized in that
the first controller (C, C_1, C_2, C_3)
is configured to calculate a temperature range that is operational for the chiller (<NUM>, 1_1, 1_2, 1_3) based on an inlet water temperature measured by the first sensor (IS, IS_1, IS_2, IS_3), an outlet water temperature measured by the second sensor (OS, OS_1, OS_2, OS_3), and an outside air temperature measured by the third sensor (S, S_1, S_2, S_3), and then output information on the calculated temperature range to the second controller (<NUM>).