Air conditioning system

Abstract

Provided is an air conditioning system capable of reducing the power consumption of a heat source machine. For this purpose, a control device (100) of an air conditioning system comprises a resistance calculation unit (123) for calculating a load-side resistance on the basis of a load-side differential pressure detected by a differential pressure gauge and a load-side flow rate detected by a flow meter, a minimum machine count determination unit (124) for determining the minimum start-up machine count for a primary pump (2) that corresponds to the load-side resistance, a pump control unit (122) for controlling the operation of a plurality of primary pumps (2) so that the start-up machine count for the primary pump (2) is equal to or greater than the minimum start-up machine count, and a heat source machine control unit (121) for controlling the operation of a plurality of heat source machines (1) so as to start the heat source machine (1) corresponding to the activated primary pump (2).

Description

air conditioning system

[0001] The present disclosure relates to air conditioning systems.

[0002] In an air conditioning system, a controller calculates the resistance values ​​of the utilization side piping and the air-cooled heat exchanger for the utilization side circuit based on pressure data measured by a differential pressure sensor and flow rate data obtained by a flow rate sensor, and determines the power consumption of the secondary pump using the resistance values, and controls the determined power consumption of the secondary pump so as to be as small as possible (see, for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2014-035090

[0004] However, in the air conditioning system shown in Patent Document 1, although efforts are made to reduce the amount of power consumed by the secondary pump, this does not lead to energy savings in the heat source equipment, which accounts for the majority of the power consumed by the air conditioning system, and the reduction in power consumption remains limited.

[0005] The present disclosure has been made to solve these problems, and its purpose is to provide an air conditioning system that can reduce the amount of power consumed by the heat source unit and the amount of energy consumed by the entire air conditioning system.

[0006] An air conditioning system according to the present disclosure includes a plurality of heat source machines that heat or cool a heat medium, a plurality of heat source machine-side pumps that are provided corresponding to the plurality of heat source machines and that circulate the heat medium heated or cooled by the heat source machines between the heat source machines and a load, a differential pressure gauge that detects the pressure difference between the pressure of the heat medium flowing into the load and the pressure of the heat medium flowing out of the load, a flow meter that detects the flow rate of the heat medium flowing into the load or the flow rate of the heat medium flowing out of the load, and a control device that controls the plurality of heat source machines and the plurality of heat source machine-side pumps. The control device includes a resistance calculation unit that calculates a load-side resistance, which is the resistance to the heat medium circulating through the load, based on the differential pressure detected by the differential pressure gauge and the flow rate detected by the flow meter; a minimum number determination unit that determines the minimum number of heat source machine side pumps to be started according to the load-side resistance; a pump control unit that controls the operation of the plurality of heat source machine side pumps so that the number of heat source machine side pumps to be started is equal to or greater than the minimum number; and a heat source machine control unit that controls the operation of the plurality of heat source machines so as to start the heat source machine corresponding to the started heat source machine side pump.

[0007] According to the air conditioning system of the present disclosure, it is possible to reduce the amount of power consumed by the heat source unit, and it is possible to reduce the amount of energy consumed by the entire air conditioning system.

[0008] Fig. 1 is a diagram showing a heat medium circuit of an air conditioning system according to embodiment 1. Fig. 2 is a block diagram showing the configuration of a control device for the air conditioning system according to embodiment 1. Fig. 3 is a flow chart showing an example of the operation of the air conditioning system according to embodiment 1. Fig. 4 is a diagram showing an example of the energy consumption efficiency of a heat source unit in the air conditioning system according to embodiment 1. Fig. 5 is a flow chart showing an example of the operation of a modified example of the air conditioning system according to embodiment 1. Fig. 6 is a flow chart showing an example of the operation of a modified example of the air conditioning system according to embodiment 1. Fig. 7 is a diagram showing an example of the configuration for realizing the functions of the control device for the air conditioning system according to embodiment 1.

[0009] An embodiment of an air conditioning system according to the present disclosure will be described with reference to the accompanying drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations are appropriately simplified or omitted. For convenience, the following description may express the positional relationship of each structure based on the illustrated state. Note that the present disclosure is not limited to the following embodiments, and any combination of the embodiments, any modification of any component of each embodiment, or any omission of any component of each embodiment are possible within the scope of the present disclosure.

[0010] Embodiment 1. Embodiment 1 of the present disclosure will be described with reference to Figures 1 to 7. Figure 1 is a diagram showing a heat medium circuit of an air conditioning system. Figure 2 is a block diagram showing the configuration of a control device for the air conditioning system. Figure 3 is a flow diagram showing an example of the operation of the air conditioning system. Figure 4 is a diagram showing an example of the energy consumption efficiency of a heat source unit in the air conditioning system. Figures 5 and 6 are each flow diagrams showing an example of the operation of a modified example of the air conditioning system. Figure 7 is a diagram showing an example of the configuration for realizing the functions of the control device for the air conditioning system.

[0011] The air conditioning system according to this embodiment is a chiller-type air conditioning system that uses water as a heat medium. However, the heat medium used in the air conditioning system is not limited to water. Brine may also be used as the heat medium.

[0012] 1 shows the configuration of a water circuit (heat medium circuit) of an air conditioning system according to this embodiment. As shown in the figure, the air conditioning system includes a plurality of heat source units 1 and an air conditioner 11. In the illustrated example, the air conditioning system includes a first heat source unit 1a, a second heat source unit 1b, and a third heat source unit 1c as the plurality of heat source units 1. In the present disclosure, the first heat source unit 1a, the second heat source unit 1b, and the third heat source unit 1c are collectively referred to as "heat source units 1" without distinction.

[0013] The air conditioning system is equipped with one or more air conditioners 11. In the illustrated example, the air conditioning system is equipped with two air conditioners 11: a first air conditioner 11a and a second air conditioner 11b. In the present disclosure, the first air conditioner 11a and the second air conditioner 11b are collectively referred to as the "air conditioners 11" without distinction. The air conditioner 11 is a load in the air conditioning system.

[0014] The heat source unit 1 and the air conditioner 11 are connected in a circular manner by a water pipe 10. The water pipe 10 is a heat medium pipe through which water, which is a heat medium, flows. This forms a water circuit between the heat source unit 1 and the air conditioner 11, in which water, which is a heat medium, circulates through the water pipe 10. Multiple heat source units 1 are connected in parallel in the water circuit. In the present disclosure, the side of the water circuit on which the heat source unit 1 is provided may be referred to as the heat source unit side. Furthermore, the side of the water circuit on which the air conditioner 11 is provided may be referred to as the load side.

[0015] The heat source unit 1 is an air-source heat pump that heats or cools water, which is a heat medium. Water heated or cooled by the heat source unit 1 is discharged from a water outlet of the heat source unit 1. A heat source unit outlet piping 3, which is part of the water piping 10, is connected to the water outlet of the heat source unit 1. In the illustrated example, the first heat source unit outlet piping 3a is connected to the water outlet of the first heat source unit 1a, the second heat source unit outlet piping 3b is connected to the water outlet of the second heat source unit 1b, and the third heat source unit outlet piping 3c is connected to the water outlet of the third heat source unit 1c. In the present disclosure, the first heat source unit outlet piping 3a, the second heat source unit outlet piping 3b, and the third heat source unit outlet piping 3c are collectively referred to as the "heat source unit outlet piping 3" without distinction. Each heat source unit outlet piping 3 is connected to a first outbound header 4.

[0016] Furthermore, a heat source unit inlet side pipe 14, which is part of the water piping 10, is connected to the water inlet of the heat source unit 1. In the illustrated example, the first heat source unit inlet side pipe 14a is connected to the water inlet of the first heat source unit 1a, the second heat source unit inlet side pipe 14b is connected to the water inlet of the second heat source unit 1b, and the third heat source unit inlet side pipe 14c is connected to the water inlet of the third heat source unit 1c. In the present disclosure, the first heat source unit inlet side pipe 14a, the second heat source unit inlet side pipe 14b, and the third heat source unit inlet side pipe 14c are collectively referred to as the "heat source unit inlet side pipe 14" without distinction. Each heat source unit inlet side pipe 14 is connected to a return header 6.

[0017] The air conditioning system includes a primary pump 2. The primary pump 2 is a heat source unit-side pump that circulates the heat medium heated or cooled by the heat source unit 1 between the heat source unit 1 and the air conditioner 11, which is the load. A primary pump 2 is provided corresponding to each of the multiple heat source units 1. In other words, multiple primary pumps 2 are provided, more precisely, the same number as the heat source units 1.

[0018] In the configuration example described here, the first primary pump 2a corresponds to the first heat source unit 1a, the second primary pump 2b corresponds to the second heat source unit 1b, and the third primary pump 2c corresponds to the third heat source unit 1c. In the present disclosure, the first primary pump 2a, the second primary pump 2b, and the third primary pump 2c are collectively referred to as the "primary pumps 2" when they are not distinguished from each other. The primary pumps 2 are provided in the water piping 10 between the return header 6 and each heat source unit 1, i.e., in the heat source unit inlet side piping 14. In the illustrated example, the first primary pump 2a is provided in the first heat source unit inlet side piping 14a, the second primary pump 2b is provided in the second heat source unit inlet side piping 14b, and the third primary pump 2c is provided in the third heat source unit inlet side piping 14c.

[0019] The first outbound header 4 and the return header 6 are connected by a bypass pipe 5. For example, when more hot water or cold water than required on the load side is supplied from the heat source unit 1, part of the water from the heat source unit 1 can be made to flow from the first outbound header 4 to the return header 6 via the bypass pipe 5 without passing through the air conditioner 11, and returned to the heat source unit 1. A second outbound header 8 is provided downstream of the first outbound header 4. A secondary pump 7 is connected between the first outbound header 4 and the second outbound header 8. The secondary pump 7 is a pump that sends the water from the heat source unit 1, which has joined at the first outbound header 4, to the load side.

[0020] An air conditioner 11, which serves as a load, is connected between the second outbound header 8 and the return header 6. In the illustrated example, the first air conditioner 11a and the second air conditioner 11b are connected in parallel. That is, the water pipe 10 connected to the second outbound header 8 branches and is connected to the water inlet of the first air conditioner 11a and the water inlet of the second air conditioner 11b, respectively. The water pipes 10 connected to the water outlets of the first air conditioner 11a and the second air conditioner 11b, respectively, merge and are connected to the return header 6.

[0021] A flow control valve 12 is provided in the water pipe 10 between the water outlet of the air conditioner 11 and the return header 6. The flow control valve 12 is for adjusting the flow rate of water in each air conditioner 11. The flow control valve 12 is, for example, an electric valve whose opening can be continuously changed. A first flow control valve 12a is provided between the first air conditioner 11a and the return header 6, and a second flow control valve 12b is provided between the second air conditioner 11b and the return header 6. In the present disclosure, the first flow control valve 12a and the second flow control valve 12b are collectively referred to as the "flow control valve 12" without distinction.

[0022] The air conditioning system further includes a differential pressure gauge 9 and a flow meter 13. The differential pressure gauge 9 detects the pressure difference between the heat medium flowing into the load and the heat medium flowing out of the load. The differential pressure gauge 9 is a sensor that detects the difference in water pressure at two measurement points in the water circuit. In the illustrated example, the measurement points of the differential pressure gauge 9 are the first outbound header 4 and the second outbound header 8. That is, the differential pressure gauge 9 detects the water supply differential pressure between the input side and the output side of the secondary pump 7. However, the measurement points of the differential pressure gauge 9 are not limited to this example. Any measurement point may be used as long as the differential pressure gauge 9 can detect a pressure equivalent to the pressure difference before and after the flow into and out of the air conditioner 11, which is the load. Other examples of measurement points for the differential pressure gauge 9 include the second outbound header 8 and the return header 6.

[0023] The flow meter 13 detects the flow rate of the heat medium in the load. The flow rate of the heat medium in the load may be either the flow rate of the heat medium flowing into the load or the flow rate of the heat medium flowing out of the load. In other words, the flow meter 13 detects the flow rate of the heat medium flowing into the load or the flow rate of the heat medium flowing out of the load. In the illustrated example, the flow meter 13 is provided in the water piping 10 between the air conditioner 11 and the return header 6. Therefore, in this example, the flow meter 13 detects the load flow rate of water returning from the air conditioner 11 to the return header 6.

[0024] The air conditioning system further includes a control device 100. The control device 100 controls the operation of the entire air conditioning system, including the multiple heat source units 1 and the multiple primary pumps 2. An example of the configuration of the control device 100 is shown in Figure 2. As shown in the figure, the control device 100 includes a memory unit 110, a heat source unit control unit 121, a pump control unit 122, a resistance calculation unit 123, and a minimum unit number determination unit 124. The memory unit 110 stores various types of information used by the control device 100 to control the air conditioning system.

[0025] The heat source machine control unit 121 controls the operation of the multiple heat source machines 1. The heat source machine control unit 121 controls the start and stop of each heat source machine 1. Furthermore, for a heat source machine 1 that has started up and is in operation, the heat source machine control unit 121 controls the operating frequency of a compressor (not shown) that the heat source machine 1 is equipped with.

[0026] The pump control unit 122 controls the operation of the multiple primary pumps 2 and the secondary pump 7. The pump control unit 122 controls the start and stop of each primary pump 2. More specifically, the pump control unit 122 controls the operation of the primary pumps 2 in conjunction with the operating state of the heat source unit 1. That is, the pump control unit 122 operates the primary pump 2 corresponding to the heat source unit 1 that has been started and is in operation. Furthermore, the pump control unit 122 controls the operating frequency of the primary pump 2 that is in operation, thereby controlling the flow rate of that primary pump 2.

[0027] The pump control unit 122 controls the operation of the secondary pump 7 so that the flow rate of the secondary pump 7 is equal to the sum of the flow rates of the primary pumps 2. By controlling in this way, water is prevented from flowing through the bypass piping 5, thereby suppressing unnecessary heating or cooling of water by the heat source unit 1 and suppressing a decrease in the utilization efficiency of the water heated or cooled by the heat source unit 1.

[0028] The resistance calculation unit 123 calculates the load-side resistance. The load-side resistance is the resistance to the heat medium (water) flowing through the air conditioner 11, which is the load. The resistance calculation unit 123 calculates the load-side resistance based on the differential pressure detected by the differential pressure gauge 9 and the flow rate detected by the flow meter 13. Specifically, the resistance calculation unit 123 calculates the load-side resistance value α using the following relational expression (1). In expression (1), ΔP is the load-side differential pressure detected by the differential pressure gauge 9, and Q is the load-side flow rate detected by the flow meter 13.

[0029] ΔP = α × Q ２ ... (1)

[0030] When the air conditioning system is started, the control device 100 performs a resistance measurement operation. During the resistance measurement operation, one heat source unit 1 and one primary pump 2 are operated. That is, the heat source unit control unit 121 starts one of the multiple heat source units 1. The pump control unit 122 also operates the primary pump 2 corresponding to the started heat source unit 1. At this time, the operating frequency of the primary pump 2 is fixed to a temporary value, for example, 60 Hz. Then, the pump control unit 122 starts the secondary pump 7 after starting the heat source unit 1 and the primary pump 2.

[0031] After starting the heat source unit 1, the primary pump 2, and the secondary pump 7, the system waits for a certain period of time until the operation of the system stabilizes. Then, the resistance calculation unit 123 calculates the load-side resistance using the above-mentioned relational expression (1) based on the differential pressure detected by the differential pressure gauge 9 and the flow rate detected by the flow meter 13.

[0032] The minimum number determination unit 124 determines the minimum number of primary pumps 2 to be activated according to the load-side resistance calculated by the resistance calculation unit 123. The minimum number determination unit 124 calculates the minimum number of primary pumps 2 that must be operated to generate a rated differential pressure at the load-side resistance calculated by the resistance calculation unit 123, and determines this as the minimum number of primary pumps 2 to be activated. Here, the rated differential pressure is the differential pressure on the load side when the flow rate of the heat medium (water) flowing through the load (air conditioner 11) is the rated flow rate. Furthermore, the rated flow rate is the flow rate of the heat medium (water) at which the load (air conditioner 11) can exert its rated capacity.

[0033] The minimum number determination unit 124 determines the minimum number of primary pumps 2 to be activated that satisfies the rated differential pressure and the rated flow rate, for example, by using the P-Q characteristics of the primary pump 2. The P-Q characteristics of the primary pump 2 indicate the relationship between the discharge pressure P and the flow rate Q of the primary pump 2. Data related to the P-Q characteristics of the primary pump 2 is stored in advance, for example, in the storage unit 110 of the control device 100. The minimum number determination unit 124 refers to the P-Q characteristic data of the primary pump 2 stored in the storage unit 110, and determines the minimum number of primary pumps 2 to be activated that satisfies the rated differential pressure and the rated flow rate for the load-side resistance calculated by the resistance calculation unit 123.

[0034] In this way, when the air conditioning system is started, the control device 100 performs a resistance measurement operation, finds the load-side resistance in this resistance measurement operation, and uses the found load-side resistance to determine the minimum number of primary pumps 2 to be activated. Once the minimum number of primary pumps 2 to be activated has been determined, the control device 100 ends the resistance measurement operation and starts main operation. In main operation, the pump control unit 122 controls the operation of the multiple primary pumps 2 so that the number of primary pumps 2 to be activated is equal to or greater than the minimum number. Then, the heat source machine control unit 121 controls the operation of the multiple heat source machines 1 so as to start the heat source machines 1 corresponding to the activated primary pumps 2.

[0035] Next, an example of the flow of operation of the air conditioning system configured as above will be described with reference to Figure 3. When the air conditioning system is started in step S1, the control device 100 starts a resistance measurement operation. During the resistance measurement operation, in step S2, the heat source unit control unit 121 starts one heat source unit 1. In the following step S3, the pump control unit 122 starts the operation of the primary pump 2 corresponding to the started heat source unit 1. Then, in step S4, the pump control unit 122 starts the secondary pump 7.

[0036] In the following step S5, the differential pressure gauge 9 detects the differential pressure before and after the secondary pump 7, i.e., the differential pressure on the load side. Then, in step S6, the flow meter 13 detects the flow rate on the load side. After step S6, the control device 100 then performs the process of step S7. In step S7, the resistance calculation unit 123 calculates the load-side resistance based on the differential pressure detected by the differential pressure gauge 9 in step S5 and the flow rate detected by the flow meter 13 in step S6.

[0037] In the following step S8, the minimum number determination unit 124 determines the minimum number of primary pumps 2 to be activated that satisfies the rated differential pressure and rated flow rate, based on the load-side resistance calculated by the resistance calculation unit 123 in step S7. After step S8, the control device 100 then performs the processing of step S9. In step S9, the control device 100 ends the resistance measurement operation and starts main operation. In main operation, the heat source machine control unit 121 controls the operation of the heat source machines 1, and the pump control unit 122 controls the operation of the primary pumps 2, so that the number of activated primary pumps 2 is equal to or greater than the minimum number to be activated.

[0038] Even during this operation, detection of the load-side differential pressure and flow rate continues. That is, in step S10, the differential pressure gauge 9 detects the differential pressure across the secondary pump 7 (load-side differential pressure). Then, in step S11, the flow meter 13 detects the load-side flow rate. After step S11, the control device 100 next performs processing in step S12. In step S12, the control device 100 determines whether the flow rate of the primary pump 2 during operation is excessive or insufficient. If the flow rate of the primary pump 2 is not excessive or insufficient, the processing proceeds to step S13, and the control device 100 continues the current operation. On the other hand, if it is determined in step S12 that the flow rate of the primary pump 2 is excessive or insufficient, the control device 100 returns to step S7 and continues processing.

[0039] In an air conditioning system configured as described above, the air conditioning system can be started with the minimum number of heat source units 1 and primary pumps 2 that satisfy the rated differential pressure and rated flow rate of the load, allowing the heat source units 1 to perform at their optimum capacity from the time of start-up and enabling energy-saving operation. This also makes it possible to reduce the amount of power consumed by the heat source units, which account for the majority of the power consumed by the air conditioning system, and thus reduce the amount of energy consumed by the entire air conditioning system.

[0040] In the air conditioning system of this embodiment, as shown in FIG. 2 , the control device 100 may further include a power consumption specifying unit 125. The power consumption specifying unit 125 specifies the total power consumption of a plurality of heat source units 1 according to a combination of the number of activated heat source units 1 and the operating frequencies of the compressors of the heat source units 1. FIG. 4 shows an example of the relationship between the operating frequencies of the compressors of the heat source units 1 and the efficiency of the heat source units 1. The efficiency of the heat source units 1 shown here is the COP (Coefficient of Performance), which is also known as energy consumption efficiency or coefficient of performance. In other words, the efficiency shown in FIG. 4 indicates the heating capacity and cooling capacity of the heat source units 1 per unit of power consumption.

[0041] The memory unit 110 of the control device 100 stores information related to the energy consumption efficiency of the heat source units 1. The power consumption determination unit 125 refers to the information related to the energy consumption efficiency of the heat source units 1 stored in the memory unit 110, and determines the total power consumption of the multiple heat source units 1 according to the combination of the number of activated heat source units 1 and the operating frequencies of the compressors of the heat source units 1.

[0042] The heat source machine control unit 121 then controls the operating frequency of the compressor of the heat source machine 1 based on the total power consumption identified by the power consumption identification unit 125. For example, the heat source machine control unit 121 identifies a combination that minimizes total power consumption among combinations of the number of activated heat source machines 1 and the operating frequencies of the compressors of the heat source machines 1 such that the number of activated heat source machines 1 is equal to or greater than the minimum number of activated machines described above. In this case, the heat source machine control unit 121 references information on the energy consumption efficiency of the heat source machines 1 and identifies the combination that provides the best energy consumption efficiency for the heat source machines 1 as the combination that minimizes total power consumption. The heat source machine control unit 121 then controls the operation of the multiple heat source machines 1 based on the combination of the number of activated heat source machines 1 and the operating frequencies of the compressors of the heat source machines 1 identified in this way.

[0043] Specifically, for example, when the minimum number of activated units is two, the combinations of the number of activated heat source units 1 and the operating frequencies of the compressors of the heat source units 1 are as follows: two activated units, each with an operating frequency of 60 Hz; three activated units, each with an operating frequency of 40 Hz; four activated units, each with an operating frequency of 30 Hz; six activated units, each with an operating frequency of 20 Hz, etc. The heat source unit control unit 121 identifies, from these combinations of the number of activated units and operating frequencies, the one that provides the best energy consumption efficiency for the heat source units 1 as a whole, i.e., the one that minimizes total power consumption, and controls the operation of the heat source units 1 based on that combination.

[0044] Next, with reference to Figure 5, an example of the flow of operation in a modified example of an air conditioning system equipped with a power consumption specifying unit 125 will be described. Steps S1 to S12 are the same as those in Figure 3, so repeated explanations will be omitted. If it is determined in step S12 that the flow rate of the primary pump 2 is neither excessive nor insufficient, the control device 100 then performs the process of step S21. In step S21, the power consumption specifying unit 125 refers to information regarding the energy consumption efficiency of the heat source units 1 stored in the memory unit 110 and specifies the total power consumption of the multiple heat source units 1 according to the combination of the number of activated heat source units 1 and the operating frequencies of the compressors of the heat source units 1. After step S21, the control device 100 then performs the process of step S22.

[0045] In step S22, the heat source machine control unit 121 determines the optimal number of activated heat source machines 1 and the operating frequency of the compressor based on the total power consumption identified in step S21. Then, in the following step S23, the heat source machine control unit 121 controls the operation of the heat source machines 1 at the optimal number of activated machines and the operating frequency of the compressor determined in step S22.

[0046] According to a modified example of an air conditioning system equipped with such a power consumption determination unit 125, it is possible to optimize the number of heat source units 1 that are activated and the operating frequency of the compressor, thereby further reducing the amount of energy consumed.

[0047] In the air conditioning system of this embodiment, as shown in FIG. 2 , the control device 100 may further include an information acquisition unit 130. The information acquisition unit 130 acquires information including one or more of the room temperature of the space to be air-conditioned, the outdoor air temperature, and the temperature of the heat medium in the water circuit. When acquiring the room temperature of the space to be air-conditioned, the information acquisition unit 130 acquires the room temperature from, for example, a room temperature sensor installed in the space to be air-conditioned. When acquiring the outdoor air temperature, the information acquisition unit 130 acquires the outdoor air temperature from, for example, an outdoor air temperature sensor installed outdoors. When acquiring the temperature of the heat medium in the water circuit, the information acquisition unit 130 acquires the temperature of water, which is the heat medium, from a water temperature sensor installed in the water piping 10.

[0048] In this case, the minimum number determination unit 124 determines the minimum number of primary pumps 2 to be activated based on the load-side resistance calculated by the resistance calculation unit 123 and the information acquired by the information acquisition unit 130. First, the minimum number determination unit 124 calculates the minimum number of primary pumps 2 to be activated that are necessary to ensure the rated differential pressure and rated flow rate, based on the load-side resistance calculated by the resistance calculation unit 123. Then, the minimum number determination unit 124 determines whether a preset condition for increasing the number of activated pumps is satisfied, based on the information acquired by the information acquisition unit 130. Specific examples of the condition for increasing the number of activated pumps include the following:

[0049] - When the air conditioning system starts cooling operation, the room temperature is equal to or higher than a predetermined first standard room temperature. - When the air conditioning system starts heating operation, the room temperature is equal to or lower than a predetermined second standard room temperature. - When the air conditioning system starts cooling operation, the outside air temperature is equal to or higher than a predetermined first standard outside air temperature. - When the air conditioning system starts heating operation, the outside air temperature is equal to or lower than a predetermined second standard outside air temperature. - When the air conditioning system starts cooling operation, the water temperature in the water circuit is equal to or higher than a predetermined first standard water temperature. - When the air conditioning system starts heating operation, the water temperature in the water circuit is equal to or lower than a predetermined second standard water temperature.

[0050] The first reference room temperature is set to, for example, 30°C. The second reference room temperature is set to, for example, 10°C. The first reference outside air temperature is set to, for example, 35°C. The second reference outside air temperature is set to, for example, 0°C. The first reference water temperature is set to, for example, 20°C. And the second reference water temperature is set to, for example, 5°C.

[0051] When such a condition for increasing the number of activated units is met, the environmental load is high, and simply activating the minimum number of heat source units 1 required to ensure the rated differential pressure and rated flow rate may result in insufficient heating and cooling capacities of the heat source units 1. Therefore, when the condition for increasing the number of activated units is met, the minimum number determination unit 124 determines the minimum number of primary pumps 2 to be activated, calculated based on the load-side resistance, and required to ensure the rated differential pressure and rated flow rate, plus a preset number, as the minimum number of primary pumps 2 to be activated. In this way, it is possible to achieve both a reduction in energy consumption by suppressing the activation of unnecessary heat source units 1 when the air conditioning system is started, and prevention of insufficient heating and cooling capacities of the heat source units 1.

[0052] Next, an example of the operational flow in a modified example of an air conditioning system equipped with an information acquisition unit 130 will be described with reference to Figure 6. Steps S1 to S12 are the same as those in Figure 3, so repeated explanations will be omitted. If it is determined in step S12 that the flow rate of the primary pump 2 is neither excessive nor insufficient, the control device 100 then performs the process of step S31. In step S31, the information acquisition unit 130 acquires information including one or more of the room temperature of the space to be air-conditioned, the outdoor air temperature, and the temperature of the heat medium in the water circuit. After step S31, the control device 100 then performs the process of step S32.

[0053] In step S32, the minimum number determination unit 124 determines whether the activation number addition condition is satisfied based on the information acquired by the information acquisition unit 130 in step S31. If the activation number addition condition is satisfied, the minimum number determination unit 124 determines the current minimum activation number of primary pumps 2 plus a preset number as the minimum activation number of primary pumps 2 corresponding to the environmental load. In the following step S33, the heat source machine control unit 121 and the pump control unit 122 control the operation of the heat source machines 1 and the primary pumps 2 with the activation number determined in step S32 according to the environmental load.

[0054] FIG. 7 is a diagram showing an example of a configuration for realizing the functions of the control device 100 in this embodiment. The functions of the control device 100 are realized, for example, by a processing circuit. The processing circuit may include a processor 101 and a memory 102. The processing circuit may also be dedicated hardware 103. A part of the processing circuit may be formed as dedicated hardware 103, and the processing circuit may further include a processor 101 and a memory 102. In the example shown in the figure, a part of the processing circuit is formed as dedicated hardware 103. Furthermore, in the example shown in the figure, the processing circuit further includes a processor 101 and a memory 102.

[0055] The processing circuitry, part of which is at least one dedicated hardware 103, may be, for example, a single circuit, a multiple circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. If the processing circuitry comprises at least one processor 101 and at least one memory 102, the functionality of the control device 100 may be realized by software, firmware, or a combination of software and firmware.

[0056] The software and firmware are written as programs and stored in memory 102. The processor 101 realizes the functions of each unit by reading and executing the programs stored in memory 102. The processor 101 is also called a CPU (Central Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP. The memory 102 may be, for example, a non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, or EEPROM, or a magnetic disk, flexible disk, optical disk, compact disk, minidisk, DVD, etc.

[0057] In this way, the processing circuit of the control device 100 can realize each function of the control device 100 by hardware, software, firmware, or a combination of these. When the processing circuit of the control device 100 includes at least a processor 101 and a memory 102, the processor 101 executes a program stored in the memory 102 in the control device 100, and the hardware and software of the control device 100 work together to realize the functions of each part of the control device 100. Note that the air conditioning system is not limited to a configuration in which operation is controlled by a single control device 100. The operation of the air conditioning system may also be controlled by multiple devices working together.

[0058] The present disclosure can be used in an air conditioning system that includes a plurality of heat source units that heat or cool a heat medium, and a plurality of heat source unit-side pumps that are provided corresponding to each of the plurality of heat source units and circulate the heat medium heated or cooled by the heat source units between the heat source units and a load.

[0059] 1 Heat source unit 1a First heat source unit 1b Second heat source unit 1c Third heat source unit 2 Primary pump 2a First primary pump 2b Second primary pump 2c Third primary pump 3 Heat source unit outlet side piping 3a First heat source unit outlet side piping 3b Second heat source unit outlet side piping 3c Third heat source unit outlet side piping 4 First forward header 5 Bypass piping 6 Return header 7 Secondary pump 8 Second forward header 9 Differential pressure gauge 10 Water piping 11 Air conditioner 11a First air conditioner 11b Second air conditioner 12 Flow control valve 12a First flow control valve 12b Second flow control valve 13 Flow meter 14 Heat source unit inlet side piping 14a First heat source unit inlet side piping 14b Second heat source unit inlet side piping 14c Third heat source unit inlet side piping 100 Control device 101 Processor 102 Memory 103 Dedicated hardware 110 Storage unit 121 Heat source machine control unit 122 Pump control unit 123 Resistance calculation unit 124 Minimum number determination unit 125 Power consumption specification unit 130 Information acquisition unit

Claims

1. A system comprising: a plurality of heat source machines that heat or cool a heat medium; a plurality of heat source machine-side pumps that are provided corresponding to each of the plurality of heat source machines and that circulate the heat medium heated or cooled by the heat source machine between the heat source machine and a load; a differential pressure gauge that detects the differential pressure between the pressure of the heat medium flowing into the load and the pressure of the heat medium flowing out of the load; a flow meter that detects the flow rate of the heat medium flowing into the load or the flow rate of the heat medium flowing out of the load; and a control device that controls the plurality of heat source machines and the plurality of heat source machine-side pumps, wherein the control device comprises: a resistance calculation unit that calculates a load-side resistance that is resistance to the heat medium circulating through the load based on the differential pressure detected by the differential pressure gauge and the flow rate detected by the flow meter; a minimum number determination unit that determines the minimum number of heat source machine-side pumps that can be started in accordance with the load-side resistance; and a pump control unit that controls the operation of the plurality of heat source machine-side pumps so that the number of heat source machine-side pumps that can be started in equal to or greater than the minimum number of start-up units. An air conditioning system comprising: a heat source unit control unit that controls the operation of the plurality of heat source units so as to start the heat source unit corresponding to the activated heat source unit-side pump.

2. An air conditioning system as described in claim 1, further comprising a power consumption determination unit that determines the total power consumption of multiple heat source machines according to a combination of the number of heat source machines that are activated and the operating frequency of the compressors of the heat source machines, and the heat source machine control unit controls the operating frequency of the compressors of the heat source machines based on the total power consumption determined by the power consumption determination unit.

3. The air conditioning system described in claim 2, wherein the heat source machine control unit identifies, based on the total power consumption identified by the power consumption identification unit, a combination of the number of heat source machines that are activated and the operating frequencies of the compressors of the heat source machines that results in the smallest total power consumption, among combinations of the number of heat source machines that are activated and the operating frequencies of the compressors of the heat source machines that results in the smallest total power consumption, and controls the operation of the multiple heat source machines using the identified combination.

4. An air conditioning system as described in any one of claims 1 to 3, further comprising an information acquisition unit that acquires information including one or more of the room temperature of the space to be air-conditioned, the outdoor air temperature, and the temperature of the heat medium, wherein the minimum number determination unit determines the minimum number of pumps to be activated on the heat source unit side based on the load side resistance and the information acquired by the information acquisition unit.

Images