JP6639677B2 - Heat source system - Google Patents

Description

  The present invention relates to a heat source system that includes a heat source unit and is used for, for example, an air conditioning chilling system.

  2. Description of the Related Art In general, a chilling system that heats and cools an aqueous medium by exchanging heat in a heat medium side heat exchanger between a refrigerant in a refrigerant circuit and an aqueous medium in a water pipe is known. Among them, in the air-cooled chilling system, frost may occur on the air-side heat exchanger serving as the evaporator during heating. Therefore, in such a chilling system, it is necessary to defrost the air-side heat exchanger. 2. Description of the Related Art Conventionally, an air-cooled chilling system in which a plurality of heat source units are connected to a water pipe has proposed a defrosting operation method (for example, see Patent Document 1). Patent Literature 1 discloses a defrosting operation method in a heat source system including two or more heat source units, which avoids simultaneous defrosting of the heat source units as much as possible and prevents a decrease in water temperature.

JP 2013-108732 A

However, in the defrost control of Patent Document 1, the water temperature decreases in a single defrost operation in which only one heat source unit is operated.

  The present invention has been made to solve the above-described problem, and provides a heat source system in which a decrease in supply water temperature is suppressed even during a defrosting operation regardless of the number of heat source units. With the goal.

A heat source system according to the present invention is a heat source system and a control device for controlling the heat source unit and the heat source unit for heating and cooling of the fluid, the heat source unit includes a compressor and a refrigerant flow switching device and the air-side heat fluid exchanger and the pressure reducing device and the heat medium heat exchanger and the refrigerant circuit connected via a refrigerant pipe, the refrigerant heat-exchanged Ru flow of Rihiya medium circuit by the heat medium side heat exchanger flows comprising pipe and, provided in the flow body piping, a fluid pump for supplying fluid body to the heating medium side heat exchanger, an inlet temperature sensor for measuring the temperature of the incoming to that flow body to the heating medium side heat exchanger, the , control apparatus, when the defrosting operation of the air-side heat exchanger condenser such Rinetsu medium side heat exchanger is an evaporator, the flow rate of the supplied Ru Fluid to the heating medium side heat exchanger inlet to vary according to the fluid temperature measured by mouth temperature sensor, a flow body pump control And operation control means for, when the defrosting operation, with the measured fluid temperature and a temperature determining means for determining low or not than a first set temperature, the operation control means, when the defrosting operation were measured When it is determined that the fluid temperature is lower than the first set temperature, the supplied flow rate of the fluid is made higher than the normal flow rate .

  According to the heat source system of the present invention, since the flow rate of the fluid supplied to the heat medium-side heat exchanger changes according to the fluid temperature, the heat capacity changes and the outlet temperature also changes. Therefore, even in the single operation of the heat source unit, the temperature drop of the supply hot water during the defrosting operation can be controlled.

It is a schematic structure figure at the time of heating operation of the heat source system concerning Embodiment 1 of the present invention. It is a schematic structure figure at the time of the defrost operation of the heat source system concerning Embodiment 1 of the present invention. FIG. 3 is a functional block diagram of the control device according to the first embodiment of the present invention. 2 is a flowchart illustrating a fluid flow control according to the first embodiment of the present invention. It is a graph which shows the relationship between an inlet temperature and the evaporation temperature which freezes. It is a graph which shows the relationship between the water flow rate and the evaporation temperature which freezes. 3 is a flowchart illustrating a freeze control according to the first embodiment of the present invention. It is a schematic structure figure of a heat source system concerning Embodiment 2 of the present invention. 9 is a flowchart illustrating a fluid flow rate control according to the second embodiment of the present invention. 9 is a flowchart illustrating control of a conventional device.

  Hereinafter, the heat source system of the present invention will be described with reference to the drawings. The heat source system 100 is an air-cooled chilling system, and is used, for example, as a central heat source for air conditioning inside a building. The heat source system 100 performs a heating operation, a cooling operation, or the like based on the operation content specified by the user. During operation of the heat source system 100, heat is exchanged between the refrigerant flowing through the refrigerant pipe 11 of the refrigerant circuit 2 and the fluid flowing through the fluid pipe 22, and the fluid is heated or cooled. The fluid heated or cooled by the heat source system 100 is supplied to a load-side device such as an air conditioner. In the embodiment, a case where the fluid is a hydrothermal medium such as an antifreeze will be described as an example.

Embodiment 1 FIG.
(Configuration of heat source system 100)
FIG. 1 is a schematic configuration diagram of the heat source system according to Embodiment 1 of the present invention during a heating operation. FIG. 2 is a schematic configuration diagram of the heat source system according to Embodiment 1 of the present invention during a defrosting operation. The configuration of the heat source system 100 will be described below based on FIGS. 1 and 2.

  The heat source system 100 includes a heat source unit 1 and a control device 50. The heat source unit 1 includes a refrigerant circuit 2, a fluid pipe 22 through which a water heat medium flows, a fluid pump 20, and a pump control device 21. The compressor 3, the refrigerant flow switching device 4, the air-side heat exchanger 5, the decompression device 7, the heat medium-side heat exchanger 8, and the accumulator 9 are connected to the refrigerant circuit 2 via the refrigerant pipe 11. .

  The compressor 3 draws low-temperature and low-pressure refrigerant and compresses the refrigerant into a high-temperature and high-pressure state. The compressor 3 includes, for example, a capacity-controllable inverter compressor. The refrigerant flow switching device 4 is configured by, for example, a four-way valve or the like, and switches between the flow of the refrigerant during the cooling operation or the defrosting operation and the flow of the refrigerant during the heating operation.

  The pressure reducing device 7 is configured by, for example, an electronic expansion valve or the like, and expands the refrigerant by reducing the pressure. The accumulator 9 is provided on the suction side of the compressor 3 and stores the condensed liquid refrigerant. The accumulator 9 prevents the liquid refrigerant from being sucked into the compressor 3 as it is.

  The air-side heat exchanger 5 exchanges heat between the air and the refrigerant, and functions as an evaporator during a heating operation, and functions as a condenser during a cooling operation or a defrosting operation. Further, the air-side heat exchanger 5 is provided with an air-side heat exchanger blower 6 composed of, for example, a propeller fan or the like, and the air-side heat exchanger blower 6 sends air to the air-side heat exchanger 5. Supplying.

  The heat medium side heat exchanger 8 exchanges heat between the refrigerant and the water heat medium. The heating medium-side heat exchanger 8 causes heat exchange between the high-temperature and high-pressure refrigerant and the water heat medium during the heating operation to generate high-temperature water, and causes heat exchange between the low-temperature and low-pressure refrigerant and the water heat medium during the cooling operation. To produce cold water.

  The fluid pump 20 supplies a water heating medium to the heat medium side heat exchanger 8 via a fluid pipe 22. The fluid pump 20 has, for example, a configuration in which the rotation speed is controlled, and supplies the water in multiple stages, such as a maximum flow rate, a large flow rate, a normal flow rate, and a small flow rate, from the one with the larger flow rate FR.

  The pump control device 21 receives a control signal from a control device 50 described later, and changes the frequency at which the fluid pump 20 is operated in accordance with the control signal. A heat medium is supplied. For example, the pump control device 21 has a multi-step driving frequency such as a maximum frequency, a large frequency, a normal frequency, and a small frequency, and rotates the pump motor at the driving frequency.

  The heat source unit 1 further includes sensor groups 12 to 17 such as a plurality of temperature sensors and pressure sensors. The low pressure sensor 12 is provided in a suction pipe of the compressor 3 and detects a compressor suction pressure. The suction gas temperature sensor 13 is provided on the suction side of the compressor 3 and detects the temperature of the suction gas of the refrigerant drawn into the compressor. The outside air temperature sensor 15 detects an outside air temperature. Further, the evaporation temperature sensor 14 is provided at an intermediate position of a refrigerant pipe flowing through the heat medium-side heat exchanger 8, and measures the refrigerant temperature (evaporation temperature Te) at the location.

  The high-temperature water sent from the heat source system 100 during the heating operation is sent to the load-side device, and is used for heating in the load-side device to become low-temperature water, for example, and is supplied to the heat medium-side heat exchanger 8 of the heat source system 100 again. Is heated. The water heating medium is thus circulating between the load-side device and the heat source system 100 via the fluid pipe 22.

  The inlet temperature sensor 16 is provided in the fluid pipe 22 on the inlet side of the heat medium side heat exchanger 8, and measures the water temperature (inlet temperature Twi) at the installation position. The outlet temperature sensor 17 is provided in the fluid pipe 22 on the outlet side of the heat medium side heat exchanger 8, and measures the water temperature (outlet temperature Two) at the installation position.

  The control device 50 is configured by, for example, a microcomputer or the like, and controls the heat source system 100. Specifically, the control device 50 determines the pressure of the refrigerant from a group of sensors such as the low-pressure pressure sensor 12, the intake gas temperature sensor 13, the evaporation temperature sensor 14, the outside air temperature sensor 15, the inlet temperature sensor 16, and the outlet temperature sensor 17. Information and temperature information, temperature information of the water heating medium, and the like are received. The control device 50 controls the operation based on the information acquired from the sensor groups 12 to 17, the operation information of the heat source unit 1, and the command content input by the user. Specifically, the control device 50 controls the operation and stop of the compressor 3 or the control of the rotation speed, the opening degree adjustment of the pressure reducing device 7, the rotation control of the air-side heat exchanger blower 6, and the control of the accumulator 9. . Further, the control device 50 changes the water flow rate FR of the water heating medium supplied to the heat medium side heat exchanger 8 by the fluid pump 20 during the defrosting operation.

(Operation of heat source unit 1 during defrosting)
In the heating operation for heating the water heat medium, when frost formation is detected in the air-side heat exchanger 5, the control device 50 switches the flow of the refrigerant in the refrigerant circuit 2 and melts the attached frost by the heat of the refrigerant. I do. The frost detection of the air-side heat exchanger 5 is performed, for example, when a temperature sensor is provided in the air-side heat exchanger 5 to measure the refrigerant temperature, and when the measured temperature becomes equal to or lower than a preset threshold temperature. Detects frost formation. In the defrosting operation of the air-side heat exchanger 5, as shown in FIG. 2, the air-side heat exchanger 5 serves as a condenser, and the heat medium-side heat exchanger 8 serves as an evaporator. Therefore, since a low-temperature refrigerant flows into the heat medium-side heat exchanger 8, the water heat medium is cooled in the heat medium-side heat exchanger 8.

(Functions of the control device 50)
FIG. 3 is a functional block diagram of the control device according to Embodiment 1 of the present invention. The control device 50 will be described based on FIG. The control device 50 includes an operation control unit 51, a temperature determination unit 52, a freeze determination unit 53, and a storage unit 54.

  The operation control unit 51 controls the operation of the refrigerant circuit 2 and the flow rate of the fluid pump 20 based on the temperature information and the pressure information from the sensor groups 12 to 17. Specifically, the operation control means 51 adjusts the operation frequency of the compressor 3 such that, for example, the outlet temperature Two measured by the outlet temperature sensor 17 approaches the set target temperature. The operation control means 51 also controls the water flow rate FR of the water heat medium supplied to the heat medium side heat exchanger 8 by the fluid pump 20 via the pump control device 21 during the defrosting operation of the air side heat exchanger 5. Change. Specifically, the operation control unit 51 transmits a control signal for adjusting the drive frequency of the fluid pump 20 to the pump control device 21. The pump control device 21 changes the driving frequency according to the control signal, and changes the rotation speed of the fluid pump 20. In addition, the operation control unit 51 transmits the operation information in execution to the temperature determination unit 52 and the freeze determination unit 53. Further, the operation control unit 51 changes the supplied water flow rate FR based on the determination result of the temperature determination unit 52, and continues or terminates the defrosting operation based on the result of the freeze determination unit 53.

  The temperature determining means 52 acquires temperature information from the inlet temperature sensor 16 and determines the level of the water temperature. Specifically, at the time of the defrosting operation, it is determined whether or not the inlet temperature Twi measured by the inlet temperature sensor 16 is lower than the first set temperature T1, and the determination result is transmitted to the operation control means 51. In addition, during the defrosting operation, it is determined whether or not the measured inlet temperature Twi is lower than the second set temperature T2, and the determination result is transmitted to the operation control unit 51 or the freeze determination unit 53 according to the determination result. When the temperature determination is requested, the temperature determination unit 52 refers to the first set temperature T1 and the second set temperature T2 stored in the storage unit 54.

  The freezing determination unit 53 obtains the inlet temperature Twi from the inlet temperature sensor 16 and obtains the evaporation temperature Te from the evaporation temperature sensor 14. Further, the freeze determination unit 53 determines from the operation control unit 51 whether the heat source system 100 is performing the heating operation, the cooling operation, or the defrosting operation mode, and at which water flow rate the fluid pump 20 operates. Operation information such as whether the operation has been performed is acquired. Then, the freeze determination unit 53 freezes the heat medium-side heat exchanger 8 when the temperature determination unit 52 determines that the measured inlet temperature Twi is lower than the second set temperature T2 during the defrosting operation. Freezing determination control is performed to determine whether or not this is the case. In the freeze determination control, the freeze determination means 53 determines the heat medium side heat based on the water flow rate FR supplied to the heat medium side heat exchanger 8, the measured inlet temperature Twi, and the measured evaporation temperature Te. It is determined whether the exchanger 8 is frozen. Specifically, with reference to the freezing threshold information T3 stored in the storage means 54, the freezing evaporation temperature Tf according to the supplied water flow rate FR and the measured inlet temperature Twi is calculated. Further, the freezing determination means 53 compares the measured evaporation temperature Te with the calculated freeze evaporation temperature Tf. When the measured evaporation temperature Te is lower than the freeze evaporation temperature Tf, the freeze determination means 53 determines that the heat medium side heat exchanger 8 is frozen, while the measured evaporation temperature Te is the freeze evaporation temperature. When it is higher than Tf, it is determined that the heat medium-side heat exchanger 8 does not freeze. In addition, the freeze determination unit 53 transmits the freeze determination result to the operation control unit 51. That is, the freeze determination unit 53 can change the end timing of the defrosting operation performed by the operation control unit 51.

  The storage unit 54 is configured by a memory such as a ROM, for example, and sets and stores a first set temperature T1, a second set temperature T2, and freezing threshold information T3 in advance. The first set temperature T1 is, for example, an inlet temperature at a boundary where a decrease in the water temperature of the water heating medium sent from the heat source system 100 becomes remarkable when the heat source unit 1 performs the defrosting operation. The first set temperature T1 may be configured to be automatically set based on the cooling capacity of the refrigerant circuit, a target outlet temperature, a normal water flow rate, and the like. The second set temperature T2 is, for example, a temperature lower than the first set temperature and higher than a normal freezing temperature of the heat medium-side heat exchanger 8. The freezing threshold information T3 is information on the correspondence between the inlet temperature Twi and the freezing evaporation temperature and information on the correspondence between the water flow rate FR and the freezing evaporation temperature, and the freezing determination means 53 calculates the freezing and evaporation temperature Tf. This is what is referred to when doing. The freezing threshold value information T3 may be stored in any form, such as a formula or a table, as long as the freezing threshold value T3 or the evaporation temperature at which the water is frozen corresponding to the water flow rate FR is changed and stored. It may be stored.

(Pump control during defrost)
FIG. 4 shows a flowchart of the fluid flow control according to the first embodiment of the present invention. During the defrosting operation, the refrigerant flows in the same direction as the cooling operation, so that the outlet temperature Two becomes lower than the inlet temperature Twi. Therefore, during the defrosting operation, there is a concern that the supply water temperature of the heat source system 100 decreases, the heat medium side heat exchanger 8 freezes, and the like. On the other hand, in the fluid flow rate control of FIG. 4, the drive frequency of the fluid pump 20 is changed to change the water flow rate FR. The cooling capacity of the refrigerant circuit 2 is defined by the product of the water flow rate FR and the difference between the inlet temperature Twi and the outlet temperature Two. Therefore, when the cooling capacity and the inlet temperature Twi are constant, a decrease in the outlet temperature Two is suppressed when the water flow rate FR is higher than when the water flow rate FR is low.

  In the heat source system 100, for example, when the heating operation of the heat source unit 1 is started, the control device 50 starts the fluid flow control of FIG. First, the operation control means 51 determines whether or not the heat source unit 1 is in a defrosting operation (step ST101). When the defrosting operation is not being performed (step ST101; NO), the operation control unit 51 controls the water flow rate FR supplied by the fluid pump 20 to be the normal water flow rate (step ST104). Specifically, the operation control unit 51 transmits a control signal to the pump control device 21, and the pump control device 21 rotates the fluid pump 20 at a normal frequency (for example, 40 Hz) according to the control signal. On the other hand, when the defrosting operation is being performed (step ST101; YES), the operation control unit 51 notifies the temperature determination unit 52. Upon receiving the notification from the operation control unit 51, the temperature determination unit 52 obtains information on the inlet temperature Twi from the inlet temperature sensor 16 of the heat source unit 1, and obtains the first set temperature T1 from the storage unit 54. Then, temperature determining means 52 determines whether or not the acquired inlet temperature Twi is equal to or lower than first set temperature T1 (step ST102). The first set threshold value is a preset water temperature, for example, 30 ° C. here. The temperature determination unit 52 notifies the operation control unit 51 of the determination result. The operation control means 51 receives the notification from the temperature determination means 52, and when the inlet temperature Twi is equal to or lower than the first set temperature T1 (step ST102; YES), the supplied water flow rate FR is increased (step ST103). ). Specifically, the rotational speed of the fluid pump 20 is increased to “maximum” (for example, 60 Hz) via the pump control device 21 to suppress a decrease in the outlet temperature Two with respect to the inlet temperature Twi. On the other hand, when the inlet temperature Twi is higher than the first set temperature T1, the operation control means 51 sets the supplied water flow rate FR to the normal water flow rate (step ST104). After performing step ST103 or step ST104, the operation control means 51 returns to step ST101, and repeats the fluid flow control of steps ST101 to ST104. When the heating operation ends, the operation control unit 51 ends the fluid flow control.

(Freezing evaporation temperature Tf)
By the way, an increase in the amount of water is effective in suppressing the freezing of the heat medium side heat exchanger 8 in addition to suppressing the decrease in the outlet temperature Two. FIG. 5 is a graph showing the relationship between the inlet temperature and the freezing evaporation temperature. When the inlet temperature Twi is high, the freezing evaporation temperature decreases, while when the inlet temperature Twi is low, the freezing evaporation temperature increases. For example, when the water flow rate FR and the evaporating temperature Te as the cooling capacity of the refrigerant circuit 2 are constant, if the inlet temperature Twi of the water heating medium is low, the outlet temperature Twoo is also reduced accordingly, and the water is easily frozen. Become.

  FIG. 6 is a graph showing the relationship between the water flow rate and the freezing evaporation temperature. If the flow rate FR of water supplied to the heat medium side heat exchanger 8 is large, the evaporation temperature at which the water freezes decreases, while if the flow rate FR of water is small, the evaporation temperature at which the water freezes increases. For example, when the water flow rate FR is large, even when the inlet temperature Twi and the evaporating temperature Te are constant, the heat capacity of the water heat medium flowing through the heat medium side heat exchanger 8 increases, so that a decrease in the outlet temperature Twoo is suppressed, The heat medium-side heat exchanger 8 is in a state where it is difficult to freeze.

  Further, the freezing of the heat medium side heat exchanger 8 is suppressed based on the evaporation temperature Te using the relationship between the inlet temperature Twi and the freezing evaporation temperature and the relationship between the water flow rate FR and the freezing evaporation temperature. You can also. In the heat source system 100 in which the water flow rate FR changes, the heat capacity changes according to the change in the water flow rate FR. Therefore, when the freezing of the heat medium-side heat exchanger 8 is detected during the defrosting operation of the air-side heat exchanger 5, a decrease in the inlet temperature Twi or the outlet temperature Two is detected as in the related art, and the defrosting operation is terminated. In the case of controlling, it is necessary to set the threshold value of the freeze detection to a high temperature for safety.

  FIG. 7 shows a flowchart of the freezing control according to Embodiment 1 of the present invention. When the inlet temperature Twi is lower than the predetermined temperature, the controller 50 detects freezing by comparing the evaporation temperature Te with the freezing evaporation temperature Tf with respect to the inlet temperature Twi and the water flow rate FR.

  In the heat source system 100, for example, when the heating operation of the heat source unit 1 is started, the control device 50 starts the refrigeration control of FIG. Then, first, the operation control means 51 determines whether or not the heat source unit 1 is in a defrosting operation (step ST111). When the defrosting operation is being performed (step ST111; YES), the operation control unit 51 notifies the temperature determination unit 52. On the other hand, if the defrosting operation is not being performed (step ST111; NO), the operation control unit 51 returns to step 111 and monitors whether the defrosting operation has been started during the heating operation. Next, upon receiving the notification from the operation control unit 51, the temperature determination unit 52 obtains the temperature information of the inlet temperature Twi from the inlet temperature sensor 16 of the heat source unit 1, and obtains the second set temperature T2 from the storage unit 54. I do. Then, temperature determining means 52 determines whether or not the acquired inlet temperature Twi is equal to or lower than the second set temperature (step ST112). The second set temperature T2 is a preset water temperature, for example, 15 ° C. here. When the operation control unit 51 determines that the inlet temperature Twi is equal to or lower than the second set temperature T2 (step ST112; YES), the temperature determination unit 52 notifies the freeze determination unit 53. On the other hand, when the inlet temperature Twi is higher than the second set temperature (step ST112; NO), the temperature determination unit 52 notifies the operation control unit 51. When the operation control unit 51 receives the notification from the temperature determination unit 52, the operation control unit 51 continues the defrosting operation (step ST115). On the other hand, when the freeze determination unit 53 receives the notification from the temperature determination unit 52, the evaporating temperature sensor 14 and the inlet The temperature information is obtained from the temperature sensor 16. Further, the freezing determination unit 53 acquires operation information on the water flow rate set in the fluid pump 20 from the operation control unit 51. Then, the freezing determination means 53 calculates the freezing / evaporating temperature Tf according to the evaporation temperature Te, the inlet temperature Twi, and the water flow rate FR with reference to the freezing threshold information T3 in the storage means 54. Further, the freezing determination means 53 determines whether or not the obtained evaporation temperature Te is equal to or lower than the calculated freeze evaporation temperature Tf (step ST113). The result of the freeze determination is notified from the freeze determination unit 53 to the operation control unit 51. When the evaporation temperature Te is equal to or lower than the freezing evaporation temperature Tf (step ST113; YES), the operation control unit 51 ends the defrosting operation (step ST114). That is, when the water heat medium having the set water flow rate FR and the inlet temperature Twi has passed through the heat medium-side heat exchanger 8 having the evaporation temperature Te, the water temperature is so low that the water is cooled at the outlet temperature. In this case, the defrosting operation is terminated, and the occurrence of freezing is suppressed. On the other hand, when the evaporation temperature Te is higher than the freeze evaporation temperature Tf (step ST113; NO), the operation control unit 51 determines that the heat medium-side heat exchanger 8 does not freeze and continues the defrosting operation (step ST113). ST115). After terminating or continuing the defrosting operation in step ST114 or step ST115, the operation control means returns to step ST111 and repeats the freezing control. The operation control means ends the freezing control when the heating operation ends.

  The freezing control is effective in the heat source system 100 in which the water flow rate FR supplied by the fluid pump 20 to the heat medium-side heat exchanger 8 changes, because it is possible to perform the freezing determination in consideration of the change in the water flow rate FR. The control device 50 can be implemented using both the freezing control shown in FIG. 7 and the flow rate control shown in FIG.

  As described above, in the first embodiment, the heat source system 100 includes the heat source unit 1 that performs heating and cooling of the fluid and the control device 50 that controls the heat source unit 1. A refrigerant circuit 2 in which a refrigerant flow switching device 4, an air-side heat exchanger 5, a decompression device 7, and a heat medium-side heat exchanger 8 are connected via a refrigerant pipe 11, and a heat medium-side heat exchanger 8. A fluid pipe 22 through which a fluid that exchanges heat with the refrigerant in the refrigerant circuit 2 flows; a fluid pump 20 provided in the fluid pipe 22 to supply the fluid to the heat medium-side heat exchanger 8; The controller 50 includes an inlet temperature sensor 16 for measuring the temperature of the flowing fluid, and the controller 50 performs a defrosting operation when the air-side heat exchanger 5 becomes a condenser and the heat medium-side heat exchanger 8 becomes an evaporator. Supplied to the heat medium side heat exchanger 8 As the fluid flow rate changes according to the fluid temperature Twi measured by the inlet temperature sensor 16 that is one having the operation control means 51 for controlling the fluid pump 20.

  Thus, regardless of whether the heat source unit 1 that constitutes the heat source system 100 is composed of a single unit or a plurality of units, the temperature decrease of the water heating medium supplied from the heat source system 100 during defrosting is suppressed. You.

  Further, the control device 50 further includes a temperature determination unit 52 that determines whether the measured fluid temperature Twi is lower than the first set temperature T1 during the defrosting operation, and the operation control unit 51 performs the operation during the defrosting operation. When it is determined that the measured fluid temperature Twi is lower than the first set temperature T1, the supplied fluid flow rate FR is set to be higher than the normal flow rate.

  Thus, when the fluid temperature Two at the inlet of the heat medium-side heat exchanger 8 is low during the defrosting operation, the water flow rate FR of the supplied water heating medium is increased. Temperature drop is suppressed. Further, freezing of the heat medium-side heat exchanger 8 is suppressed.

  The heat source unit 1 further includes an evaporating temperature sensor 14 for measuring the evaporating temperature of the refrigerant, and the control device 50 further controls the supplied fluid flow rate FR, the measured fluid temperature Twi, and the evaporating temperature during the defrosting operation. The heat medium-side heat exchanger 8 includes a freezing determination unit 53 that determines whether or not the heat medium-side heat exchanger 8 freezes based on the evaporation temperature Te measured by the temperature sensor 14. When it is determined that 8 does not freeze, the defrosting operation is continued.

  Thus, the freezing control is performed in consideration of the difference in the freeze evaporation temperature Tf due to the difference in the water flow rate FR. Even when the water temperature is low, the defrosting operation of the air-side heat exchanger 5 can be continued without freezing the heat medium-side heat exchanger 8 depending on the water flow rate FR. If the freezing control is configured to increase the flow rate for suppressing freezing, the defrosting operation is continued even at a lower temperature. Therefore, even if the defrosting is incomplete, it is possible to prevent the defrosting operation from being stopped in order to prevent the heat medium side heat exchanger 8 from freezing.

  Further, the control device 50 further includes a temperature determination unit 52 that determines whether the measured fluid temperature Twi is lower than the second set temperature T2 during the defrost operation, and the freeze determination unit 53 performs the freeze determination during the defrost operation. When it is determined that the measured fluid temperature Twi is lower than the second set temperature T2, it is determined whether the heat medium-side heat exchanger 8 freezes. Thus, the control device 50 can set a threshold value for the temperature of the fluid, and use the threshold value as a condition for the freezing determination unit 53 to start the freezing determination.

  Further, the freezing determination means 53 calculates the freezing evaporation temperature Tf according to the supplied fluid flow rate FR and the measured fluid temperature Twi, and when the measured evaporation temperature Te is lower than the calculated freezing evaporation temperature Tf. Is determined to be frozen, and if the measured evaporation temperature Te is higher than the calculated freezing evaporation temperature Tf, it is determined that no freezing is performed.

  As a result, the threshold value (freezing-evaporation temperature Tf) is calculated according to the inlet temperature Twi and the water flow rate FR, so that a high-precision freezing determination is made. Therefore, for example, when the inlet temperature Twi is high or when the water flow rate FR is large, the heat source system 100 can perform the defrosting operation longer than when the defrosting operation is performed based on the conventional freezing determination.

The operation control means 51 adjusts the drive frequency of the corresponding fluid pump 20 to change the supplied fluid flow rate FR. When increasing the supplied fluid flow rate FR, the drive frequency of the fluid pump 20 is increased. the largely to smaller Ku the driving frequency of the fluid pump 20 when reducing the fluid flow rate FR is supplied. Accordingly, if the drive frequency of the fluid pump 20 is synchronized with the water flow rate FR, the control device 50 transmits the control signal according to the target water flow rate, thereby changing the water flow rate FR in multiple stages. Can be.

Embodiment 2 FIG.
In the second embodiment, the heat source system 100 includes a plurality of heat source units 1a to 1c having the same configuration as the heat source unit 1 of the first embodiment. The plurality of heat source units 1a to 1c are connected in parallel so that the fluid pipes 22a to 22c merge with each other on the upstream and downstream sides of the heat medium heat exchangers 8a to 8c. The water heating medium supplied from the hot water storage tank to the heat source system 100 branches and flows into each of the heat source units 1a to 1c at the junction on the upstream side, and is heated or cooled by each of the heat medium side heat exchangers 8a to 8c. It joins again at the downstream junction, and is sent out from the heat source system 100 and returns to the hot water storage tank. Hereinafter, in the heat source system 100 during the heating operation, a description will be given of a case where, of the plurality of heat source units 1a to 1c, the heat source unit 1a is performing the defrosting operation and the remaining heat source units 1b and 1c are not performing the defrosting operation. I do.

  FIG. 9 shows a flowchart of the fluid flow control according to the second embodiment of the present invention. Although the refrigerant circuit is not shown in FIG. 9, each of the heat source units 1 a to 1 c has the same refrigerant circuit as in the first embodiment. In the second embodiment, it is assumed that the control device 50 controls the plurality of heat source units 1a to 1c collectively, manages each of the plurality of heat source units 1a to 1c separately, and can control them individually.

(Pump control during defrosting)
In the second embodiment, when the inlet temperature Twi is higher than a predetermined temperature in the heat source unit 1a during the defrosting operation, the control device 50 supplies the fluid pump 20a of the heat source unit 1a to the heat medium side heat exchanger 8a. Water flow rate FRa is reduced. Thus, the amount of water supply of the cooled heat medium is suppressed, and a decrease in the temperature of the water sent to the hot water storage tank is suppressed. In the heat source system 100 composed of the plurality of heat source units 1a to 1c, the heat source units 1b and 1c that are not being defrosted can supply hot water, and thus are lower than in the case of the heat source system composed of a single heat source unit. The water flow rate FRa of the heat source unit 1a during the defrost can be reduced to the temperature.

  When the heating operation is started in the heat source system 100, the control device 50 starts the fluid flow control of FIG. First, the operation control means 51 determines whether or not there is a heat source unit during the defrosting operation among the plurality of heat source units 1a to 1c (step ST201). When there is no heat source unit during the defrosting operation (step ST201; NO), the operation control unit 51 sets the water flow rates FRa to FRc supplied by the fluid pumps 20a to 20c to the normal water flow rate (step ST207). Specifically, the operation control unit 51 transmits a control signal to the pump control devices 21a to 21c to rotate the fluid pumps 20a to 20c at a normal frequency (for example, 40 Hz). On the other hand, when there is the heat source unit 1a in the defrosting operation (step ST201; YES), the operation control unit 51 notifies the temperature determination unit 52. Upon receiving the notification from the operation control means 51, the temperature determination means 52 acquires information on the inlet temperature Twi from the inlet temperature sensor 16a of the heat source unit 1a during defrosting, and obtains the first set temperature T1 from the storage means 54. get. Then, temperature determining means 52 determines whether or not the acquired inlet temperature Twi is equal to or lower than first set temperature T1 (step ST202). The first set temperature T1 is a preset water temperature, and is set to, for example, 30 ° C. The temperature determination unit 52 notifies the operation control unit 51 of the determination result. The operation control unit 51 receives the notification from the temperature determination unit 52, and if the inlet temperature Twi is equal to or lower than the first set temperature T1 (step ST202; YES), the operation control unit 51 determines the water flow rate FRa of the heat source unit 1a during defrosting. The maximum water flow rate is set (step ST203). Specifically, the drive frequency of the fluid pump 20a is set to the maximum (for example, 60 Hz). The operation control means 51 sets the water flow rates FRb and FRc of the heat source units 1b and 1c that are not being defrosted to the normal water flow rates (step ST204). On the other hand, when the acquired inlet temperature Twi is higher than the first set temperature T1 (step ST202; NO), the operation control unit 51 sets the water flow rate FRa of the heat source unit 1a during defrost to a small water flow rate (step ST205). . Specifically, the operation control means 51 reduces the drive frequency of the fluid pump 20a (for example, 30 Hz). Further, the operation control means 51 increases the water flow rates FRb, FRc of the heat source units 1b, 1c that have not been defrosted (step ST206). Specifically, the operation control unit 51 increases the drive frequency of the fluid pumps 20b and 20c (for example, 50 Hz). The operation control means 51 sets the flow rate of each fluid pump in step ST204, step ST206, or step ST207, and returns to step ST201 to repeat the fluid flow rate control. When the heating operation ends, the operation control unit 51 ends the fluid flow control.

  Therefore, when the inlet temperature Twi is higher than the first set temperature T1, the supply water amount reduced in the heat source unit 1a during defrosting increases the water flow rates FRb and FRc of the heat source units 1b and 1c not performing defrosting. And a decrease in the flow rate of water supplied from the heat source system 100 is suppressed.

  The control device 50 controls the frequency of the corresponding compressor 3 so that the outlet temperature Two corresponding to the plurality of heat source units 1a to 1c becomes the target water temperature. In step ST206, in the heat source units 1b and 1c in which the defrosting operation is not being performed, the amount of water is larger than usual, so that the rise in the outlet temperature Two is suppressed, and there is a concern that the temperature becomes lower than the target water temperature. However, in the configuration in which the frequency control of the compressor 3 is performed, the compressor frequency of the heat source units 1b and 1c that are not being defrosted is increased and the heating capacity is increased. The water temperature drop is backed up.

  In step ST204, the operation control unit 51 sets the water flow rates FRb and FRc of the heat source units 1b and 1c that are not being defrosted to the normal water flow rates, but the present invention is not limited to this. For example, if the water flow rates FRb and FRc are set to a large water flow rate, the heat source unit 1a can be backed up. In addition, since the heat source unit 1a also has the maximum water flow rate in step ST203, when the heat source units 1b and 1c are operated at a large water flow rate, there is a concern that the total water amount will increase. Therefore, the operation control means 51 may be configured to set the water flow rates FRb, FRc of the heat source units 1b, 1c to low water flow rates in step ST204.

  In the second embodiment, the heat source system 100 includes a plurality of heat source units 1a to 1c, the plurality of heat source units 1a to 1c have fluid pipes 22a to 22c connected in parallel to each other, and the operation control unit 51 includes a plurality of heat source units. In the case where the first heat source unit 1a of the units 1a to 1c is in the defrosting operation and the second heat source units 1b and 1c are not in the defrosting operation, the measured fluid temperature Twi of the first heat source unit 1a is the second temperature. When it is determined that the temperature is higher than the first set temperature T1, the fluid flow rate FRa supplied to the first heat source unit 1a is made smaller than the normal flow rate, and the fluid flow rates FRb and FRc supplied to the second heat source units 1b and 1c are made normal. It is more than the flow rate.

  Thus, since the heat source system 100 includes the plurality of heat source units 1a to 1c, when the fluid temperature Twi is higher than the first set temperature T1, while reducing the flow rate cooled by the heat source unit 1a during defrosting, The supply water amount and supply temperature as a whole can be backed up by the heat source units 1b and 1c.

  Each of the heat source units 1a to 1c further includes outlet temperature sensors 17a to 17c for measuring the outlet temperature of the fluid flowing out of the heat medium side heat exchangers 8a to 8c, and the operation control unit 51 controls the second heat source unit 1b , 1c, the frequency of the compressor 3 of the second heat source units 1b, 1c is adjusted such that the outlet temperature Two approaches the set target temperature.

  Accordingly, even when the water flow rates FRb and FRc of the other heat source units 1b and 1c are large, the heating capacity is increased. Therefore, even when the heat source unit 1a is being defrosted, the temperature of the water supplied from the heat source system 100 is reduced. Reduction is suppressed.

  The embodiment of the present invention is not limited to the above embodiment, and various changes can be made. For example, in the heat source system 100 including a plurality of heat source units 1a to 1c, a case has been described in which one control device 50 controls a plurality of heat source units 1a to 1c. 1c may be configured to include the control devices 50a to 50c. In this case, for example, one control device 50a acquires the operation information and the like from the other heat source units 1b and 1c, executes the fluid flow control shown in FIG. 9, and instructs the other control devices 50b and 50c to change the water flow and the like. You only need to be notified.

  Further, the fluid pump 20 only needs to be able to change the water flow rate FR of the water heating medium to be sent out in a plurality of stages, and may be configured as a pump that obtains kinetic energy for circulating the fluid by reciprocating motion instead of rotating motion.

  Further, in the heat source system 100 according to the second embodiment, for each of the plurality of heat source units 1a to 1c, the end timing of the defrosting operation may be controlled by the freezing determination as in the first embodiment.

  Also, a case has been described where the load-side device is an air conditioner, but may be, for example, a floor heating system or a hot water supply system. In addition, a storage tank is provided between the heat source system and the load-side equipment, and the water heating medium is configured to circulate between the heat source system and the storage tower and between the storage tank and the load-side equipment. You may.

  1, 1a-1c heat source unit, 2 refrigerant circuit, 3 compressor, 4 refrigerant flow switching device, 5 air side heat exchanger, 6 air side heat exchanger blower, 7 decompression device, 8, 8a-8c heat medium side Heat exchanger, 9 accumulator, 11 refrigerant pipe, 12 low pressure pressure sensor, 13 suction gas temperature sensor, 14 evaporation temperature sensor, 15 outside air temperature sensor, 16, 16a-16c inlet temperature sensor, 17, 17a-17c outlet temperature sensor, 20, 20a-20c fluid pump, 21, 21a-21c pump control device, 22, 22a-22c fluid piping, 50 control device, 51 operation control means, 52 temperature determination means, 53 freeze determination means, 54 storage means, 100 heat source System, T1 first set temperature, T2 second set temperature, T3 freezing threshold information, FR, FRa-FRc water flow rate ( Fluid flow rate), Twi fluid temperature (inlet temperature), Two outlet temperature, Te evaporation temperature, Tf freeze evaporation temperature.

Claims (7)

In a heat source system including a heat source unit that performs heating and cooling of a fluid and a control device that controls the heat source unit,
The heat source unit,
A refrigerant circuit in which a compressor, a refrigerant flow switching device, an air-side heat exchanger, a decompression device, and a heat medium-side heat exchanger are connected via a refrigerant pipe,
Fluid piping through which the fluid that is heat-exchanged with the refrigerant of the refrigerant circuit by the heat medium-side heat exchanger,
A fluid pump that is provided in the fluid pipe and supplies the fluid to the heat medium-side heat exchanger;
An inlet temperature sensor for measuring the temperature of the fluid flowing into the heat medium-side heat exchanger,
The control device includes:
During the defrosting operation in which the air-side heat exchanger becomes a condenser and the heat medium-side heat exchanger becomes an evaporator, the flow rate of the fluid supplied to the heat medium-side heat exchanger is measured by the inlet temperature sensor. Operation control means for controlling the fluid pump so as to change according to the fluid temperature ,
A temperature determination unit configured to determine whether the measured fluid temperature is lower than a first set temperature during the defrosting operation ,
The heat source system , wherein the operation control means increases the supplied fluid flow rate than a normal flow rate when it is determined that the measured fluid temperature is lower than the first set temperature during the defrosting operation . A plurality of the heat source units are provided, and the plurality of heat source units are connected in parallel with the fluid piping,
The operation control means,
The first heat source unit is in a defrosting operation and the second heat source unit is not in a defrosting operation among the plurality of heat source units, and the measured fluid temperature of the first heat source unit is the first setting. When it is determined that the temperature is higher than the temperature, the supplied fluid flow rate of the first heat source unit is made smaller than a normal flow rate, and the supplied fluid flow rate of the second heat source unit is made larger than a normal flow rate. The heat source system according to claim 1 . Each of the heat source units further includes:
An outlet temperature sensor for measuring an outlet temperature of the fluid flowing out of the heat medium side heat exchanger,
The heat source system according to claim 2 , wherein the operation control means adjusts the frequency of the compressor of the second heat source unit so that the measured outlet temperature of the second heat source unit approaches a set target temperature. Each of the heat source units further includes:
An evaporation temperature sensor that measures an evaporation temperature of the refrigerant,
The control device further comprises:
Freezing determining means for determining whether the heat medium-side heat exchanger freezes based on the supplied fluid flow rate, the measured fluid temperature, and the measured evaporation temperature during the defrosting operation. With
The heat source system according to any one of claims 1 to 3 , wherein the operation control means continues the defrosting operation when it is determined that the heat medium-side heat exchanger does not freeze. The temperature determination means, wherein during defrosting operation, it is determined whether the measured fluid temperature is lower than the second set temperature,
The freeze determination unit determines whether the heat medium-side heat exchanger freezes when the measured fluid temperature is determined to be lower than the second set temperature during the defrosting operation. Item 5. A heat source system according to Item 4 . The freeze determination means calculates a freeze evaporation temperature according to the supplied fluid flow rate and the measured fluid temperature, and freezes when the measured evaporation temperature is lower than the calculated freeze evaporation temperature. determined, the measured heat source system according to claim 4 or 5, wherein determining the evaporation temperature does not freeze when higher than the freezing evaporator temperature the calculated. The operation control means adjusts the drive frequency of the corresponding fluid pump to change the supplied fluid flow rate, and increases the drive frequency of the fluid pump when increasing the supplied fluid flow rate. and, a heat source system of any one of claims 1 to 6 for small Ku the drive frequency of the fluid pump when to reduce the fluid flow to be the supply.

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