Air conditioner

Abstract

This chilling unit is formed by a device including compressors and comprises: a plurality of refrigerant circuits through which a refrigerant circulates; a plurality of heat medium heat exchangers that perform heat exchange between the refrigerant and a heat medium serving as a medium for conveying heat; a pump that adds pressure to the heat medium and feeds out the heat medium; an outlet temperature sensor that is provided on an outlet side of the most-downstream-side heat medium heat exchanger, and detects the temperature of the heat medium; and a control device that controls a plurality of compressors, wherein the control device activates compressors the number of which is determined in accordance with the value of the differential between the temperature detected by the outlet temperature sensor and a target temperature that is set in advance.

Description

Chilling unit and air conditioning device

[0001] The present disclosure relates to a chilling unit and an air conditioner.

[0002] Some systems perform air conditioning and other functions by configuring a heat medium circuit that circulates a heat medium containing water or brine between a chilling unit, which serves as a heat source unit, and a load unit. The chilling unit heats or cools the heat medium to supply heat to the load unit. The load unit supplies the heat supplied by the heat medium to a heat load. In the case of an air conditioning system, the load unit conditions the air by heating or cooling the air in a room.

[0003] Some chilling units are equipped with equipment that configures multiple independent refrigerant circuits (see, for example, Patent Document 1). In Patent Document 1, each refrigerant circuit is configured by piping a compressor, a four-way valve, an air heat exchanger, an expansion valve, a water heat exchanger, and an accumulator.

[0004] Patent No. 7158590

[0005] In Patent Document 1, all compressors installed in a chilling unit are started up after an operation command is issued, controlling the compressors to maximize their capacity as quickly as possible after startup. However, this control method has the problem that starting all compressors immediately after an operation command is issued increases the cooling / heating capacity at startup, which requires a large amount of heat transfer medium to be stored in the heat transfer medium circuit. Furthermore, in the case of low loads, starting all compressors installed in a chilling unit increases the cooling / heating capacity at startup too much, resulting in frequent start-stop (thermo ON / OFF) operations.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a chilling unit and air conditioning apparatus that reduces the amount of heat medium held in the heat medium circuit while reducing the frequency of starting and stopping during low load conditions.

[0007] The chilling unit according to the present disclosure is composed of equipment including compressors, and is equipped with a plurality of refrigerant circuits through which a refrigerant circulates, a plurality of heat medium heat exchangers that exchange heat between the refrigerant and a heat medium that serves as a medium for transporting heat, a pump that applies pressure to the heat medium and sends it out, an outlet temperature sensor that is provided on the outlet side of the heat medium heat exchanger that is the most downstream and that detects the temperature of the heat medium, and a control device that controls the plurality of compressors, and the control device activates the number of compressors determined according to the difference between the temperature detected by the outlet temperature sensor and a preset target temperature.

[0008] The air conditioning apparatus according to the present disclosure is also provided with a chilling unit, the chilling unit being composed of equipment including a compressor and having a plurality of refrigerant circuits through which a refrigerant circulates, a plurality of heat medium heat exchangers that exchange heat between the refrigerant and a heat medium that serves as a medium for transporting heat, and a pump that applies pressure to the heat medium and sends it out; an indoor heat exchanger that exchanges heat between the indoor air in a space to be air-conditioned and the heat medium; an indoor flow control device that adjusts the flow rate of the heat medium passing through the indoor heat exchanger; an indoor unit that is connected to the chilling unit by piping and forms a heat medium circuit that circulates the heat medium, the indoor unit having an inlet temperature sensor provided on the inlet side of the indoor heat exchanger that detects the temperature of the heat medium and an indoor temperature sensor that detects the temperature of the indoor air; and a control device that controls the plurality of compressors, the control device starting the compressor selected according to the difference between the temperature detected by the inlet temperature sensor and the temperature detected by the indoor temperature sensor.

[0009] In the chilling unit and air conditioner according to the present disclosure, the control device activates a compressor determined based on the difference between the temperature detected by the outlet temperature sensor and a preset target temperature, or based on the difference between the temperature detected by the inlet temperature sensor and the temperature detected by the room temperature sensor. In this way, by changing the number of compressors to activate based on the load, it is possible to reduce the amount of heat medium held in the heat medium circuit and reduce the frequency of start / stop operations under low load.

[0010] FIG. 1 is a diagram showing the appearance of a chilling unit according to embodiment 1. FIG. 2 is a diagram showing the configuration of an air conditioning apparatus equipped with a chilling unit according to embodiment 1. FIG. 3 is a diagram showing the configuration of a modified example of an air conditioning apparatus equipped with a chilling unit according to embodiment 1. FIG. 4 is a diagram explaining control for determining the number of units to be activated in an air conditioning apparatus equipped with a chilling unit according to embodiment 1. FIG. 5 is a diagram explaining a modified example of control for determining the number of units to be activated in an air conditioning apparatus equipped with a chilling unit according to embodiment 1. FIG. 6 is a diagram explaining control for determining the number of units to be activated in an air conditioning apparatus equipped with a chilling unit according to embodiment 2. FIG. 7 is a diagram explaining a modified example of control for determining the number of units to be activated in an air conditioning apparatus equipped with a chilling unit according to embodiment 2.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to the embodiments described below. Also, the size relationships of the components in the drawings may differ from those in reality.

[0012] Embodiment 1. Figure 1 is a diagram showing the appearance of a chilling unit 100 according to embodiment 1. The following describes chilling unit 100, which is a heat source unit that supplies heat to indoor units 200, which are load-side devices described below. In embodiment 1, the heat medium that transports heat supplied from chilling unit 100 and supplies it to indoor units 200 is water. However, this is not limited to this, and the heat medium may also be a fluid containing brine or the like.

[0013] The chilling unit 100 according to the first embodiment has a machine room 1, an air heat exchanger 2, and an outdoor fan 3. The machine room 1 is a housing that houses the devices that make up the refrigerant circuit. The machine room 1 is located below the chilling unit 100 and serves as a base that supports the chilling unit 100, so it is a housing with a rectangular bottom. The machine room 1 according to the first embodiment is a housing in the shape of a rectangular parallelepiped box. Here, the direction extending along the long side of the machine room 1 housing is referred to as the longitudinal direction. The direction extending along the short side is referred to as the short side. The direction perpendicular to the long and short sides is referred to as the height direction.

[0014] The air heat exchanger 2 is one of the components constituting the refrigerant circuit and is a fin-and-tube heat exchanger that exchanges heat between the refrigerant and outdoor air. As described below, the chilling unit 100 of the first embodiment has multiple refrigerant circuits, and in this example, it has four refrigerant circuits. Therefore, in the chilling unit 100 of the first embodiment, four air heat exchangers 2 (air heat exchanger 2A to air heat exchanger 2D) are installed in the upper part of the machine room 1. The air heat exchanger 2A and the air heat exchanger 2B, and the air heat exchanger 2C and the air heat exchanger 2D are paired, respectively. When viewed from the short side of the machine room 1 indicated by arrow A, the pair of air heat exchangers 2 are arranged opposite each other with a wide gap between them on the upper side, forming a V-shape. In the chilling unit 100 of the first embodiment, two pairs of air heat exchangers 2 are arranged side by side in the longitudinal direction of the machine room 1.

[0015] The outdoor fan 3 is a propeller fan that passes outdoor air through the air heat exchanger 2. The outdoor fan 3 is disposed above the pair of air heat exchangers 2, between the V-shaped portions of the pair of air heat exchangers 2. The chilling unit 100 according to the first embodiment has four outdoor fans 3 (outdoor fan 3A to outdoor fan 3D).

[0016] FIG. 2 is a diagram showing the configuration of an air conditioning system equipped with a chilling unit 100 according to the first embodiment. The dashed arrows in FIG. 2 indicate the flow of water, which serves as a heat medium. As shown in FIG. 2, the air conditioning system according to the first embodiment includes a chilling unit 100 and two indoor units 200 (indoor unit 200A and indoor unit 200B). The chilling unit 100 has four refrigerant circuits 101 (refrigerant circuits 101A to 101D). The chilling unit 100 also has two groups of two refrigerant circuits 101, and the two groups of refrigerant circuits 101 share one water heat exchanger 60. The chilling unit 100 also includes a control device 110. The air conditioner is equipped with a heat medium circuit 102, which is composed of a main heat medium circuit 103 in which one pump 80, two water heat exchangers 60 (water heat exchanger 60A and water heat exchanger 60B), and one cushion tank 81 are connected in series by heat medium piping, and branch heat medium circuits 104 (branch heat medium circuit 104A and branch heat medium circuit 104B) that branch off from the heat medium piping between the two water heat exchangers 60 and the cushion tank 81 in the main heat medium circuit 103, flow through indoor units 200, and then return to the main heat medium circuit 103. Each indoor unit 200 has a branch heat medium circuit 104. The water flowing through the heat medium circuit 102 is cooled or heated in two stages by the two water heat exchangers 60.

[0017] As shown in Figure 2, the refrigerant circuit 101 of each system of the chilling unit 100 according to the first embodiment is configured by connecting a compressor 30, a four-way valve 50, an air heat exchanger 2, an expansion valve 70, a water heat exchanger 60, and an accumulator 40 by refrigerant piping. The refrigerant that flows through the refrigerant circuit 101 can be, for example, a single refrigerant such as R-22 or R-134a, a pseudo-azeotropic refrigerant mixture such as R-410A or R-404A, or a non-azeotropic refrigerant mixture such as R-407C. Also, CF4, which contains a double bond in its chemical formula, can be used. ３ CF=CH ２ Refrigerants with relatively low global warming potential, such as CO ２ Natural refrigerants such as propane can be used.

[0018] The compressors 30 (compressors 30A to 30D) compress and discharge the drawn refrigerant. The compressors 30 are driven via a compressor inverter drive device (not shown) or the like. The compressors 30 can change the capacity of the compressors 30, which is the amount of refrigerant delivered per unit time, by arbitrarily changing the drive frequency based on instructions from the control device 110.

[0019] Furthermore, the four-way valve 50 (four-way valves 50A to 50D) serving as a flow path switching device switches the flow of refrigerant depending on the operation being performed, based on instructions from the control device 110. For example, during cooling operation, the four-way valve 50 causes the high-temperature, high-pressure refrigerant discharged from the compressor 30 to flow into the air heat exchanger 2. During heating operation, the four-way valve 50 causes the high-temperature, high-pressure refrigerant discharged from the compressor 30 to flow into the water heat exchanger 60.

[0020] As described above, the air heat exchanger 2 (air heat exchanger 2A to air heat exchanger 2D) exchanges heat between the refrigerant and the outside air. In heating operation (heating water), the air heat exchanger 2 functions as an evaporator, exchanging heat between the low-pressure refrigerant flowing in from the expansion valve 70 side and the air, evaporating the refrigerant. In cooling operation (cooling water), the air heat exchanger 2 functions as a condenser, exchanging heat between the low-pressure refrigerant flowing in from the compressor 30 side and the air, condensing the refrigerant to a liquid. As described above, the outdoor fan 3 (outdoor fan 3A to outdoor fan 3D) sends air into the air heat exchanger 2 to promote heat exchange between the refrigerant and the air. The outdoor fan 3 is driven via a fan inverter drive device (not shown) or the like. The outdoor fan 3 can change its airflow by arbitrarily changing its drive frequency based on instructions from the control device 110. In FIG. 2, the air heat exchangers 2 and the outdoor fans 3 are in one-to-one correspondence, but this is not limitative.

[0021] The water heat exchangers 60 (water heat exchanger 60A and water heat exchanger 60B) serving as heat medium heat exchangers exchange heat between water, which serves as a heat medium, and the refrigerant. The water heat exchangers 60 serve as flow paths for the two refrigerant circuits 101 and the heat medium circuit 102. Therefore, the water heat exchangers 60 constitute both the refrigerant circuit 101 and the heat medium circuit 102. For example, during heating operation, the water heat exchanger 60 functions as a condenser, exchanging heat between the refrigerant flowing in from the compressor 30 side and water, condensing the refrigerant to liquefy or convert it into a two-phase gas-liquid mixture, and heating the water. On the other hand, during cooling operation, the water heat exchanger 60 functions as an evaporator, exchanging heat between the refrigerant flowing in from the expansion valve 70 side and water, evaporating the refrigerant to cool the water.

[0022] The expansion valves 70 (expansion valves 70A to 70D) serving as throttling devices adjust the pressure of the refrigerant passing through the water heat exchanger 60, for example, by changing their opening degrees. The expansion valves 70 according to the first embodiment are configured as electronic expansion valves that change their opening degrees based on instructions from the control device 110. However, the invention is not limited to this, and the expansion valves 70 may be, for example, temperature-sensitive expansion valves that change their opening degrees based on the temperature of the refrigerant.

[0023] The accumulators 40 (accumulators 40A to 40D) are provided on the suction side of the compressors 30, respectively, and store surplus refrigerant in the refrigerant circuit 101.

[0024] The pump 80 is one of the devices that make up the heat medium circuit 102. In the heat medium circuit 102, the pump 80 sucks water, applies pressure, and sends it out to circulate. A pump inverter drive device (not shown) can change the capacity of the pump 80 by arbitrarily changing the drive frequency based on instructions from the control device 110. The cushion tank 81 is one of the devices that make up the heat medium circuit 102. The cushion tank 81 is provided on the suction side of the pump 80, and stores excess water in the heat medium circuit 102.

[0025] The control device 110 controls various devices and controls the four refrigerant circuits 101 and the heat medium circuits 102. The control device 110 realizes various functions by executing software on a computing device such as a microcomputer, or is composed of hardware such as circuit devices that realize various functions. The control device 110 is equipped with a timer 111 that measures the cumulative operating time of each compressor 30. However, this is not a limitation, and the timer 111 may be provided outside the control device 110. Note that, although the control device 110 is provided within the chilling unit 100 in FIG. 2 , this is not a limitation, and the control device 110 may be provided outside the chilling unit 100.

[0026] The indoor units 200 are units that send conditioned air to an indoor space that is the target of air conditioning. The indoor units 200 (indoor units 200A and 200B) according to Embodiment 1 shown in FIG. 2 include an indoor heat exchanger 201 (indoor heat exchanger 201A and 201B), an indoor flow control device 202 (indoor flow control device 202A and 202B), and an indoor fan 203 (indoor fan 203A and 203B). The indoor heat exchanger 201 and the indoor flow control device 202 are devices that constitute the branch heat medium circuit 104 of the heat medium circuit 102. Note that while FIG. 2 shows an air conditioning apparatus having two indoor units 200, the present invention is not limited to this, and the number of indoor units 200 may be one, or three or more.

[0027] The indoor flow control device 202 is configured, for example, as a two-way valve capable of controlling the valve opening (opening area). By adjusting its opening, the indoor flow control device 202 controls the flow rate of water flowing into and out of the indoor heat exchanger 201. The indoor flow control device 202 adjusts the amount of water passing through the indoor heat exchanger 201 based on the temperatures of the water flowing into and out of the indoor unit 200, enabling the indoor heat exchanger 201 to exchange heat at a rate appropriate to the indoor heat load. When the indoor heat exchanger 201 does not need to exchange heat with the heat load, such as when the indoor unit is stopped or the thermostat is turned off, the indoor flow control device 202 can be fully closed to stop the supply of water to and from the indoor heat exchanger 201. Note that, in FIG. 2 , the indoor flow control device 202 is installed on the heat medium piping on the water outlet side of the indoor heat exchanger 201, but this is not limited thereto. For example, the indoor flow rate control device 202 may be installed on the heat medium pipe on the water inlet side of the indoor heat exchanger 201 .

[0028] The indoor heat exchanger 201 exchanges heat between the indoor air in the indoor space supplied from the indoor fan 203 and water. When water cooler than the air passes through the heat transfer tube, the air is cooled and the indoor space is cooled. The indoor fan 203 passes the air in the indoor space through the indoor heat exchanger 201 and generates a flow of air that returns the air to the indoor space.

[0029] The air conditioner according to the first embodiment also includes a plurality of temperature sensors. For example, an outlet temperature sensor 20 for detecting an outlet water temperature Twoout is provided on the heat medium piping on the water outlet side of the water heat exchanger 60A, which is located downstream of the two water heat exchangers 60. Furthermore, for example, an inlet temperature sensor 21 (inlet temperature sensor 21A and inlet temperature sensor 21B) for detecting an inlet water temperature Twin of the indoor unit 200 (indoor unit 200A and indoor unit 200B) is provided on the heat medium piping on the water inlet side of the indoor heat exchanger 201. Furthermore, for example, an indoor temperature sensor 22 (indoor temperature sensor 22A and indoor temperature sensor 22B) for detecting a temperature (indoor temperature) Tr of the air-conditioned space (indoor space) in which the indoor unit 200 (indoor unit 200A and indoor unit 200B) is installed is provided on the air intake port of the indoor unit 200 (indoor unit 200A and indoor unit 200B).

[0030] FIG. 3 is a diagram showing the configuration of a modified example of an air conditioner equipped with the chilling unit 100 according to the first embodiment. The dashed arrows in FIG. 3 indicate the flow of water, which serves as a heat medium. The air conditioner according to the first embodiment may have the configuration shown in FIG. 3 instead of the configuration shown in FIG. 2. As shown in FIG. 3, the air conditioner according to the modified example of the first embodiment includes a chilling unit 100 and two indoor units 200 (indoor unit 200A and indoor unit 200B). The chilling unit 100 has four refrigerant circuits 101 (refrigerant circuits 101A to 101D). The chilling unit 100 also has two groups of two refrigerant circuits 101, each group sharing one cooling water-side water heat exchanger 5 and one chilled water-side water heat exchanger 6. The chilling unit 100 also includes a control device 110. The air conditioning system has two heat medium circuits 102 (heat medium circuit 102A and heat medium circuit 102B). One of the heat medium circuits 102A is configured by connecting one pump 80A, two cooling water side water heat exchangers 5 (cooling water side water heat exchanger 5A and cooling water side water heat exchanger 5B), one cooling tower 90, and one cushion tank 81A in series with heat medium piping. The other heat medium circuit 102B has a main heat medium circuit 103 in which one pump 80B, two chilled water side water heat exchangers 6 (chilled water side water heat exchanger 6A and chilled water side water heat exchanger 6B), and one cushion tank 81B are connected in series by heat medium piping, and branch heat medium circuits 104 (branch heat medium circuit 104A and branch heat medium circuit 104B) that branch off from the heat medium piping between the two chilled water side water heat exchangers 6 and the cushion tank 81B in the main heat medium circuit 103, flow through the indoor unit 200, and then return to the main heat medium circuit 103. Each indoor unit 200 has a branch heat medium circuit 104. The water flowing through the heat medium circuit 102 is cooled or heated in two stages by two chilled water side water heat exchangers 5 or two chilled water side water heat exchangers 6.

[0031] As shown in Fig. 3, the refrigerant circuit 101 of each system of the chilling unit 100 of the modified example of the first embodiment is configured by connecting a compressor 30, a cooling water-side water heat exchanger 5, an expansion valve 70, and a chilled water-side water heat exchanger 6 with refrigerant piping. As in the example shown in Fig. 2, the refrigerant flowing through the refrigerant circuit 101 can be, for example, a single refrigerant such as R-22 or R-134a, a pseudo-azeotropic refrigerant mixture such as R-410A or R-404A, or a non-azeotropic refrigerant mixture such as R-407C. In addition, CF ３ CF=CH ２ Refrigerants with relatively low global warming potential, such as CO ２ Natural refrigerants such as propane can be used.

[0032] The cooling tower 90 is installed outdoors and performs heat exchange between water, which serves as a heat medium, and the atmosphere to cool the water. The cooling water-side water heat exchangers 5 (cooling water-side water heat exchanger 5A and cooling water-side water heat exchanger 5B) perform heat exchange between the water cooled in the cooling tower 90 and the refrigerant. The cooling water-side water heat exchanger 5, which serves as a heat medium heat exchanger, serves as a flow path for the two refrigerant circuits 101 and the heat medium circuit 102. Therefore, it serves as a component of the refrigerant circuit 101 and a component of the heat medium circuit 102. Furthermore, the chilled water-side water heat exchangers 6 (chilled water-side water heat exchanger 6A and chilled water-side water heat exchanger 6B), which serve as heat medium heat exchangers, perform heat exchange between water and the refrigerant. The chilled water-side water heat exchanger 6 serves as a flow path for the two refrigerant circuits 101 and the heat medium circuit 102. Therefore, it serves as a component of the refrigerant circuit 101 and a component of the heat medium circuit 102. In addition, in a modified example of embodiment 1, the outlet temperature sensor 20 that detects the outlet water temperature Twoout is provided, for example, in the heat medium piping on the water outflow side of the cold water side water heat exchanger 6B, which is located downstream of the two cold water side water heat exchangers 6.

[0033] In the first embodiment, after the operation command is turned ON, specifically, when the user (the manager of the building in which the chilling unit 100 is installed) sends an operation command to the chilling unit 100, or immediately before the thermostat is switched from OFF to ON, a control is performed to determine the number of compressors 30 to be activated (hereinafter referred to as activation number determination control). The activation number determination control according to the first embodiment is described below.

[0034] FIG. 4 is a diagram illustrating control for determining the number of compressors to be activated in an air conditioner equipped with a chilling unit 100 according to the first embodiment. Arrows d1 to d4 in FIG. 4 each indicate |Twout - Twm|, with the length of the arrow representing the magnitude of the value. In the control for determining the number of compressors to be activated according to the first embodiment, |Twout - Twm|, which is the difference between the outlet water temperature Twoout detected by the outlet temperature sensor 20 and the target water temperature Twm, is calculated, and the number of compressors 30 to be activated is determined based on the value of the difference |Twout - Twm| and thresholds th1 (e.g., 7°C), th2 (e.g., 5.5°C), and th3 (e.g., 4°C).

[0035] The control device 110 starts all (four) compressors 30 when the value of the difference |Twout-Twm| satisfies the judgment formula (1): |Twout-Twm|>th1, as indicated by the size of the arrow d1. Furthermore, the control device 110 starts three compressors 30 when the value of the difference |Twout-Twm| is smaller than the size of the arrow d1, as indicated by the size of the arrow d2, and satisfies the judgment formula (2): th1≧|Twout-Twm|>th2 (<th1). Furthermore, the control device 110 starts two compressors 30 when the value of the difference |Twout-Twm| is smaller than the size of the arrow d2, as indicated by the size of the arrow d3, and satisfies the judgment formula (3): th2≧|Twout-Twm|>th3 (<th2). In addition, the control device 110 starts one compressor 30 if the value of the difference |Twout-Twm| is smaller than the size of arrow d3, as indicated by the size of arrow d4, and if the judgment formula (4): th3≧|Twout-Twm| is satisfied, or if none of the judgment formulas (1) to (3) are satisfied.

[0036] In this way, the control device 110 determines that the load is higher as the value of the difference |Twout - Twm| increases, and increases the number of compressors 30 to be activated, whereas the control device 110 determines that the load is lower as the value of the difference |Twout - Twm| decreases, and decreases the number of compressors 30 to be activated. In this way, it is possible to activate the optimal number of compressors 30 depending on the load, and to optimize the compressor capacity at startup.

[0037] Here, the threshold values ​​th1, th2, and th3 are values ​​that are set in advance by a contractor (a contractor that installs the chilling unit 100 in a building), and the target water temperature Twm is a value that is set in advance by a user using a remote control or the like.

[0038] In addition, when the control device 110 does not start all of the compressors 30, the method of determining which compressors 30 to start may be determined by the user as a priority, or the method may be determined based on the cumulative operating time. When determining which compressors 30 to start based on the cumulative operating time, the control device 110 measures the cumulative operating time of each compressor 30 using the timer 111 and starts the compressors 30 with the shortest cumulative operating time first. This can extend the average life of the compressors 30.

[0039] In the first embodiment, the number of compressors 30 to be activated is determined based on four determination formulas and three threshold values, but this is not limiting and may be less than this. Also, in the first embodiment, the number of compressors 30 to be activated is determined in divisions of 4, 3, 2, and 1 according to the value of the difference, but this is not limiting and the number of compressors 30 to be activated may be determined in divisions of (4, 3, 1), (4, 2, 1), (4, 2), (4, 1), etc. according to the value of the difference.

[0040] Figure 5 is a diagram illustrating a modified example of the control for determining the number of compressors to be activated for an air conditioner equipped with the chilling unit 100 according to the first embodiment. Note that arrows d1 to d3 in Figure 5 each indicate |Twout - Twm|, with the length of the arrow representing the magnitude of the value. For example, the number of compressors 30 to be activated is determined based on three determination formulas and two threshold values ​​as follows:

[0041] The control device 110 starts all (four) compressors 30 when the value of the difference |Twout-Twm| satisfies the judgment formula (1): |Twout-Twm|>th1, as indicated by the size of the arrow d1. Furthermore, the control device 110 starts two compressors 30 when the value of the difference |Twout-Twm| is smaller than the size of the arrow d1, as indicated by the size of the arrow d2, and satisfies the judgment formula (2): th1≧|Twout-Twm|>th2 (<th1). Furthermore, the control device 110 starts one compressor 30 when the value of |Twout-Twm| is smaller than the size of the arrow d2, as indicated by the size of the arrow d3, and satisfies the judgment formula (3): th2≧|Twout-Twm|, or when none of the judgment formulas (1) or (2) is satisfied.

[0042] As described above, the chilling unit 100 according to the first embodiment is composed of equipment including compressors 30, and is equipped with a plurality of refrigerant circuits 101 through which a refrigerant circulates, a plurality of heat medium heat exchangers that exchange heat between the refrigerant and a heat medium that serves as a medium for transporting heat, a pump 80 that applies pressure to the heat medium and sends it out, an outlet temperature sensor 20 that is provided on the outlet side of the most downstream heat medium heat exchanger and that detects the temperature of the heat medium, and a control device 110 that controls the plurality of compressors 30, and the control device 110 starts up a number of compressors 30 determined according to the difference between the temperature detected by the outlet temperature sensor 20 and a preset target temperature.

[0043] In the chilling unit 100 according to the first embodiment, the control device 110 activates a number of compressors 30 determined based on the difference between the temperature detected by the outlet temperature sensor 20 and a preset target temperature. By determining the number of compressors 30 to activate based on the load, the compressor capacity at startup can be optimized, optimizing the cooling / heating capacity. This eliminates the need to increase the amount of heat transfer medium held in the heat transfer medium circuit 102 as required in the past, when all compressors 30 were activated regardless of the load. This allows for a reduction in the amount of heat transfer medium held in the heat transfer medium circuit 102. Furthermore, because the cooling / heating capacity at startup is not excessively large, the frequency of start-up / stop (thermo ON / OFF) during low load conditions can be reduced.

[0044] Furthermore, in the chilling unit 100 according to embodiment 1, if the number of compressors 30 to be activated determined based on the difference value is not all of the compressors 30, the control device 110 determines which compressors 30 to activate based on the accumulated operating time.

[0045] According to the chilling unit 100 of the first embodiment, the compressors 30 with the shortest cumulative operating time can be started first, thereby extending the average life of the compressors 30 .

[0046] Embodiment 2 In embodiment 2, the method of controlling the number of activated units is different from that in embodiment 1. The control of determining the number of activated units according to embodiment 2 will be described below.

[0047] The timing of the control to determine the number of units to be activated in accordance with embodiment 2 is the same as that in embodiment 1. That is, after the operation command is turned ON, specifically, when the user (the manager of the building in which chilling unit 100 is installed) sends an operation command to chilling unit 100, or immediately before the thermostat changes from OFF to ON.

[0048] FIG. 6 is a diagram illustrating control for determining the number of compressors to be activated in an air conditioner equipped with a chilling unit 100 according to the second embodiment. Arrows d1 to d4 in FIG. 6 each indicate |Twin - Tr|, with the length of the arrow representing the magnitude of the value. In the control for determining the number of compressors to be activated according to the second embodiment, |Twin - Tr|, which is the difference between the inlet water temperature Twin detected by the inlet temperature sensor 21 and the room temperature Tr detected by the room temperature sensor 22, is calculated, and the number of compressors 30 to be activated is determined based on the value of the difference |Twin - Tr| and thresholds th1 (e.g., 7°C), th2 (e.g., 5.5°C), and th3 (e.g., 4°C).

[0049] The control device 110 starts all (four) compressors 30 when the value of the difference |Twin-Tr| satisfies the judgment formula (1): |Twin-Tr|>th1, as indicated by the size of the arrow d1. Furthermore, the control device 110 starts three compressors 30 when the value of the difference |Twin-Tr| is smaller than the size of the arrow d1, as indicated by the size of the arrow d2, and satisfies the judgment formula (2): th1≧|Twin-Tr|>th2 (<th1). Furthermore, the control device 110 starts two compressors 30 when the value of the difference |Twin-Tr| is smaller than the size of the arrow d2, as indicated by the size of the arrow d3, and satisfies the judgment formula (3): th2≧|Twin-Tr|>th3 (<th2). Furthermore, the control device 110 starts one compressor 30 when the value of the difference |Twin-Tr| is smaller than the magnitude of the arrow d3, as indicated by the magnitude of the arrow d4, and when the judgment formula (4): th3≧|Twin-Tr| is satisfied, or when none of the judgment formulas (1) to (3) is satisfied.

[0050] In this way, the control device 110 determines that the load is higher as the value of the difference |Twin-Tr| increases, and increases the number of compressors 30 to be activated, and determines that the load is lower as the value of the difference |Twin-Tr| decreases, and decreases the number of compressors 30 to be activated. In this way, it is possible to activate the optimal number of compressors 30 depending on the load, and to optimize the compressor capacity at startup.

[0051] Here, if there are multiple indoor units 200, the control device 110 calculates the value of the difference |Twin - Tr| for each indoor unit 200 and uses the largest of the multiple difference values ​​to determine the number of compressors 30. In other words, the control device 110 calculates the value of the difference |Twin - Tr| between the inlet water temperature Twin detected by the inlet temperature sensor 21A for indoor unit 200A and the indoor temperature Tr detected by the indoor temperature sensor 22A for indoor unit 200A, and the value of the difference |Twin - Tr| between the inlet water temperature Twin detected by the inlet temperature sensor 21B for indoor unit 200B and the indoor temperature Tr detected by the indoor temperature sensor 22B for indoor unit 200B, and if the difference value for indoor unit 200A is larger than the difference value for indoor unit 200B, the control device 110 uses the difference value for indoor unit 200A to determine the number of compressors 30.

[0052] In the second embodiment, the number of compressors 30 to be activated is determined based on four determination formulas and three threshold values, but this is not limiting and may be less than this. Also, in the second embodiment, the number of compressors 30 to be activated is determined in divisions of 4, 3, 2, and 1 according to the value of the difference, but this is not limiting and the number of compressors 30 to be activated may be determined in divisions of (4, 3, 1), (4, 2, 1), (4, 2), (4, 1), etc. according to the value of the difference.

[0053] Figure 7 is a diagram illustrating a modified example of the control for determining the number of compressors to be activated for an air conditioner equipped with a chilling unit 100 according to embodiment 2. Arrows d1 to d3 in Figure 7 each indicate |Twin-Tr|, with the length of the arrow representing the magnitude of the value. For example, the number of compressors 30 to be activated is determined based on three determination formulas and two thresholds as follows:

[0054] The control device 110 starts all (four) compressors 30 when the value of the difference |Twin-Tr| satisfies the judgment formula (1): |Twin-Tr|>th1, as indicated by the size of the arrow d1. Furthermore, the control device 110 starts two compressors 30 when the value of the difference |Twin-Tr| is smaller than the size of the arrow d1, as indicated by the size of the arrow d2, and satisfies the judgment formula (2): th1≧|Twin-Tr|>th2 (<th1). Furthermore, the control device 110 starts one compressor 30 when the value of the difference |Twin-Tr| is smaller than the size of the arrow d2, as indicated by the size of the arrow d3, and satisfies the judgment formula (3): th2≧|Twin-Tr|, or when none of the judgment formulas (1) or (2) is satisfied.

[0055] As described above, the air conditioning apparatus according to the second embodiment is configured with equipment including compressors 30, and includes a chilling unit 100 having multiple refrigerant circuits 101 through which a refrigerant circulates, multiple heat medium heat exchangers that exchange heat between the refrigerant and a heat medium that serves as a medium for transporting heat, and a pump 80 that pressurizes the heat medium and sends it out; an indoor heat exchanger 201 that exchanges heat between the indoor air in the space to be air-conditioned and the heat medium; an indoor flow rate control device 202 that adjusts the flow rate of the heat medium passing through the indoor heat exchanger 201; an indoor unit 200 that is connected to the chilling unit 100 by piping and forms a heat medium circuit 102 that circulates the heat medium, and is provided on the inlet side of the indoor heat exchanger 201 and has an inlet temperature sensor 21 that detects the temperature of the heat medium and an indoor temperature sensor 22 that detects the temperature of the indoor air; and a control device 110 that controls the multiple compressors 30, and the control device 110 activates a number of compressors 30 determined based on the difference between the temperature detected by the inlet temperature sensor 21 and the temperature detected by the indoor temperature sensor 22.

[0056] In the air conditioning apparatus according to the second embodiment, the control device 110 activates a number of compressors 30 determined according to the difference between the temperature detected by the inlet temperature sensor 21 and the temperature detected by the indoor temperature sensor 22. By determining the number of compressors 30 to be activated according to the load in this way, the compressor capacity at startup can be optimized, thereby optimizing the cooling / heating capacity. This eliminates the need to increase the amount of heat medium held in the heat medium circuit 102 as much as in the conventional case in which all compressors 30 are activated regardless of the load, thereby reducing the amount of heat medium held in the heat medium circuit 102. Furthermore, because the cooling / heating capacity at startup is not too large, the frequency of start / stop (thermo ON / OFF) during low load conditions can be reduced.

[0057] Furthermore, in the air conditioning apparatus according to embodiment 2, if the number of compressors 30 to be started determined based on the difference value is not all of the compressors 30, the control device 110 determines which compressors 30 to start based on the accumulated operating time.

[0058] According to the air conditioner of the second embodiment, compressors 30 with shorter cumulative operating times can be started first, and the average life of the compressors 30 can be extended.

[0059] 1 Machine room, 2 Air heat exchanger, 2A to 2D Air heat exchanger, 3 Outdoor fan, 3A to 3D Outdoor fan, 5 Cooling water side water heat exchanger, 5A to 5B Cooling water side water heat exchanger, 6 Chilled water side water heat exchanger, 6A to 6B Chilled water side water heat exchanger, 20 Outlet temperature sensor, 21 Inlet temperature sensor, 21A to 21B Inlet temperature sensor, 22 Indoor temperature sensor, 22A to 22B Indoor temperature sensor, 30 Compressor, 30A to 30D Compressor, 40 Accumulator, 40A to 40D Accumulator, 50 Four-way valve, 50A to 50D Four-way valve, 60 Water heat exchanger, 60A to 60B Water heat exchanger, 70 Expansion valve, 70A to 70D Expansion valve, 80 Pump, 80A to 80B Pump, 81 Cushion tank, 81A to 81B cushion tank, 90 cooling tower, 100 chilling unit, 101 refrigerant circuit, 101A to 101D refrigerant circuit, 102 heat medium circuit, 102A to 102B heat medium circuit, 103 main heat medium circuit, 104 branch heat medium circuit, 104A to 104B branch heat medium circuit, 110 control device, 111 timer, 200 indoor unit, 200A to 200B indoor unit, 201 indoor heat exchanger, 201A to 201B indoor heat exchanger, 202 indoor flow rate adjustment device, 202A to 202B indoor flow rate adjustment device, 203 indoor fan, 203A to 203B indoor fan.

Claims

1. A device including a compressor, a plurality of refrigerant circuits through which a refrigerant circulates, a plurality of heat medium heat exchangers that perform heat exchange between the heat medium that serves as a medium for transporting heat with the refrigerant, a pump that applies pressure to the heat medium and sends it out, and a chiller unit having the same, an indoor heat exchanger that exchanges heat between the indoor air of the space to be air-conditioned and the heat medium, an indoor flow rate adjustment device that adjusts the flow rate of the heat medium passing through the indoor heat exchanger, an inlet temperature sensor provided on the inlet side of the indoor heat exchanger that detects the temperature of the heat medium, an indoor temperature sensor that detects the temperature of the indoor air, and an indoor unit that is pipe-connected to the chiller unit to form a heat medium circuit that circulates the heat medium, a control device that controls a plurality of the compressors, wherein the control device activates the compressor determined according to the value of the difference between the temperature detected by the inlet temperature sensor and the temperature detected by the indoor temperature sensor air conditioner.

2. The control device increases the number of compressors to be activated as the value of the difference is larger, and decreases the number of compressors to be activated as the value of the difference is smaller The air conditioner according to Claim 1.

3. The control device when the number of compressors to be activated determined according to the value of the difference is not all of them, determines the compressor to be activated according to the operation integration time The air conditioner according to Claim 1 or 2.