JP6896054B2 - Heat source system - Google Patents

Description

The present invention relates to a heat source system including a heat source unit and used for, for example, a chilling system for air conditioning.

Generally, there is known a chilling system that heats and cools the water medium by exchanging heat between the refrigerant of the refrigerant circuit and the water medium of the water pipe by a heat exchanger on the heat medium side. Of these, in the air-cooled chilling system, frost may occur on the air side heat exchanger, which is the evaporator, during heating. Therefore, in such a chilling system, it is necessary to defrost the air side heat exchanger. Conventionally, in an air-cooled chilling system in which a plurality of heat source units are connected to water pipes, a defrosting operation method has been proposed (see, for example, Patent Document 1). Patent Document 1 discloses a defrosting operation method for preventing a decrease in water temperature by avoiding defrosting of heat source units at the same time as much as possible in a heat source system including two or more heat source units.

Japanese Unexamined Patent Publication No. 2013-108732

However, in the defrosting control of Patent Document 1, the water temperature drops in the defrosting operation of a single unit that operates only one heat source unit.

The present invention has been made to solve the above problems, and to provide 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.

The heat source system according to the present invention is a heat source system including a heat source unit that heats and cools a fluid and a control device that controls the heat source unit. The heat source unit includes a compressor, a refrigerant flow path switching device, and air side heat. A refrigerant circuit in which a exchanger, a decompression device, and a heat exchanger on the heat medium side are connected via a refrigerant pipe, and a fluid pipe through which the fluid that exchanges heat with the refrigerant in the refrigerant circuit by the heat exchanger on the heat medium side flows. A fluid pump provided in the fluid pipe to supply 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, and the refrigerant. The control device includes an evaporation temperature sensor for measuring the evaporation temperature of the heat medium, and the control device performs the heat medium during a defrosting operation in which the air side heat exchanger becomes a condenser and the heat medium side heat exchanger becomes an evaporator. An operation control means for controlling the fluid pump so that the flow rate of the fluid supplied to the side heat exchanger changes according to the fluid temperature measured by the inlet temperature sensor, and the supply during the defrosting operation. A freezing determination means for determining whether or not the heat medium side heat exchanger freezes based on the measured fluid flow rate, the measured fluid temperature, and the measured evaporation temperature, and during the defrosting operation, The freezing determination means includes a temperature determining means for determining whether or not the measured fluid temperature is lower than the second set temperature, and the freeze determining means sets the measured fluid temperature to the second set during the defrosting operation. When it is determined that the temperature is lower than the temperature, it is determined whether or not the heat exchanger on the heat medium side freezes, and the freeze determination means freezes according to the supplied fluid flow rate and the measured fluid temperature. The evaporation temperature is calculated, and if the measured evaporation temperature is lower than the calculated freeze evaporation temperature, it is determined to freeze, and if the measured evaporation temperature is higher than the calculated freeze evaporation temperature, it is frozen. The operation control means continues the defrosting operation when it is determined that the heat exchanger on the heat medium side does not freeze.

According to the heat source system of the present invention, since the temperature determination means, the freeze determination means, and the operation control means are provided, the freeze determination is more accurate than the case where the defrosting operation is performed based on the conventional freeze determination. This is done, and the defrosting operation can be carried out for a long time.

It is a schematic block diagram at the time of heating operation of the heat source system which concerns on Embodiment 1 of this invention. It is a schematic block diagram at the time of defrosting operation of the heat source system which concerns on Embodiment 1 of this invention. It is a functional block diagram of the control device which concerns on Embodiment 1 of this invention. The flowchart of fluid flow rate control which concerns on Embodiment 1 of this invention is shown. It is a graph which shows the relationship between the inlet temperature and the freezing evaporation temperature. It is a graph which shows the relationship between the water flow rate and the freezing evaporation temperature. The flowchart of the freezing control which concerns on Embodiment 1 of this invention is shown. It is a schematic block diagram of the heat source system which concerns on Embodiment 2 of this invention. It shows the flowchart of the fluid flow rate control which concerns on Embodiment 2 of this invention. It shows the flowchart of the control of the conventional apparatus.

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 the operation of the heat source system 100, heat exchange is performed 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 load-side equipment such as an air conditioner. In the embodiment, a case where the fluid is a water heat medium such as antifreeze will be described as an example.

Embodiment 1.
(Configuration of heat source system 100)
FIG. 1 is a schematic configuration diagram of a heat source system according to a first embodiment of the present invention during a heating operation. FIG. 2 is a schematic configuration diagram of the heat source system according to the first embodiment of the present invention during the defrosting operation. The configuration of the heat source system 100 will be described below with reference to 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. A compressor 3, a refrigerant flow path switching device 4, an air side heat exchanger 5, a decompression device 7, a heat medium side heat exchanger 8, and an accumulator 9 are connected to the refrigerant circuit 2 via a refrigerant pipe 11. ..

The compressor 3 sucks in a low-temperature low-pressure refrigerant and compresses the refrigerant into a high-temperature and high-pressure state. For example, the compressor 3 is composed of an inverter compressor or the like whose capacity can be controlled. The refrigerant flow path switching device 4 is composed of, 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 composed of, for example, an electronic expansion valve or the like, and decompresses and expands the refrigerant. 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 the heating operation and as a condenser during the cooling operation or the 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, and the air side heat exchanger blower 6 sends air to the air side heat exchanger 5. We are supplying.

The heat medium side heat exchanger 8 exchanges heat between the refrigerant and the water heat medium. The heat medium side heat exchanger 8 generates high temperature water by exchanging heat between a high temperature and high pressure refrigerant and a water heat medium during a heating operation, and heat exchanges a low temperature and low pressure refrigerant and a water heat medium during a cooling operation. To generate low temperature water.

The fluid pump 20 supplies a water heat medium to the heat medium side heat exchanger 8 via the fluid pipe 22. The fluid pump 20 has a configuration in which the rotation speed is controlled, for example, and supplies the water flow rate FR 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 having the largest water flow rate FR.

The pump control device 21 receives a control signal from the control device 50, which will be described later, and changes the operating frequency of the fluid pump 20 according to the control signal. It supplies a heat medium. For example, the pump control device 21 has a multi-step drive frequency such as a maximum frequency, a large frequency, a normal frequency, and a small frequency, and rotates the pump motor at the drive 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 pressure sensor 12 is installed in the suction pipe of the compressor 3 and detects the compressor suction pressure. The intake gas temperature sensor 13 is provided on the suction side of the compressor 3 and detects the suction gas temperature of the refrigerant sucked into the compressor. The outside air temperature sensor 15 detects the outside air temperature. Further, the evaporation temperature sensor 14 is provided at an intermediate position of the refrigerant pipe flowing through the heat medium side heat exchanger 8 and measures the refrigerant temperature (evaporation temperature Te) at the arrangement location.

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

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

The control device 50 is composed of, for example, a microcomputer or the like, and controls the heat source system 100. Specifically, the control device 50 receives 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. Receives information, temperature information, temperature information of the water heat medium, and the like. The control device 50 performs operation control 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 operates and stops the compressor 3, controls the rotation speed, adjusts the opening degree of the decompression device 7, controls the rotation of the air side heat exchanger blower 6, and controls the accumulator 9. .. Further, the control device 50 changes the water flow rate FR of the water heat 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)
When frost is detected in the air side heat exchanger 5 in the heating operation for heating the water heat medium, the control device 50 switches the flow of the refrigerant in the refrigerant circuit 2 and melts the adhering frost by the heat of the refrigerant. To do. The frost formation 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 the measured temperature becomes equal to or lower than a preset threshold temperature. Detect frost formation. In the defrosting operation of the air side heat exchanger 5, as shown in FIG. 2, the air side heat exchanger 5 becomes a condenser and the heat medium side heat exchanger 8 becomes an evaporator. Therefore, since the 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.

(Function of control device 50)
FIG. 3 is a functional block diagram of the control device according to the first embodiment of the present invention. The control device 50 will be described with reference to FIG. The control device 50 includes an operation control means 51, a temperature determination means 52, a freeze determination means 53, and a storage means 54.

The operation control means 51 executes the operation control of the refrigerant circuit 2 and the flow rate control of the fluid pump 20 based on the temperature information, the pressure information, and the like from the sensor groups 12 to 17. Specifically, the operation control means 51 adjusts the operation frequency of the compressor 3 so that, for example, the outlet temperature Two measured by the outlet temperature sensor 17 approaches the set target temperature. Further, the operation control means 51 determines 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 means 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 drive frequency according to the control signal and changes the rotation speed of the fluid pump 20. Further, the operation control means 51 transmits the operation information being carried out to the temperature determination means 52 and the freeze determination means 53. Further, the operation control means 51 changes the supplied water flow rate FR based on the judgment result of the temperature determination means 52, and continues or terminates the defrosting operation based on the result of the freeze determination means 53.

The temperature determining means 52 acquires temperature information from the inlet temperature sensor 16 and determines whether the water temperature is high or low. Specifically, during 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. Further, 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 means 51 or the freeze determination means 53 according to the determination result. When the temperature determination is requested, the temperature determination means 52 refers to the first set temperature T1 and the second set temperature T2 stored in the storage means 54.

The freezing determination means 53 acquires the inlet temperature Twi from the inlet temperature sensor 16 and acquires the evaporation temperature Te from the evaporation temperature sensor 14. Further, in the freezing determination means 53, from the operation control means 51, which operation mode of the heating operation, the cooling operation, or the defrosting operation is executed by the heat source system 100, and at what water flow rate the fluid pump 20 operates. Acquire driving information such as whether it is done. Then, when the temperature determination means 52 determines that the measured inlet temperature Twi is lower than the second set temperature T2 during the defrosting operation, the freeze determination means 53 freezes the heat exchanger 8 on the heat medium side. The freeze determination control for determining whether or not it is performed is performed. In the freezing determination control, the freezing determination means 53 heats the heat medium side 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 or not the exchanger 8 freezes. Specifically, the freezing evaporation temperature Tf corresponding to the supplied water flow rate FR and the measured inlet temperature Twi is calculated with reference to the freezing threshold information T3 stored in the storage means 54. Further, the freeze determination means 53 compares the measured evaporation temperature Te with the calculated freeze evaporation temperature Tf. Then, the freezing determination means 53 determines that the heat exchanger 8 on the heat medium side freezes when the measured evaporation temperature Te is lower than the freezing evaporation temperature Tf, while the measured evaporation temperature Te is the freezing evaporation temperature. If it is higher than Tf, it is determined that the heat exchanger 8 on the heat medium side does not freeze. Further, the freeze determination means 53 transmits the freeze determination result to the operation control means 51. That is, the freeze determination means 53 can change the end timing of the defrosting operation performed by the operation control means 51.

The storage means 54 is composed of, for example, a memory such as a ROM, and the first set temperature T1, the second set temperature T2, and the freezing threshold information T3 are set and stored in advance. The first set temperature T1 is an inlet temperature at a boundary where, for example, when the heat source unit 1 performs a defrosting operation, the water temperature of the water heat medium sent from the heat source system 100 drops significantly. The first set temperature T1 may be configured to be automatically set based on the cooling capacity of the refrigerant circuit, the target outlet temperature, the 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 the normal freezing temperature of the heat medium side heat exchanger 8. Further, the freezing threshold information T3 is the correspondence information between the inlet temperature Twi and the freezing evaporation temperature and the correspondence information between the water flow rate FR and the freezing evaporation temperature, and the freezing determination means 53 calculates the freezing evaporation temperature Tf. It is used as a reference when doing so. The freezing threshold information T3 is stored in any format as long as it is associated and stored as a value in which the freezing evaporation temperature changes according to the inlet temperature Twi or the water flow rate FR, as in the formula or table. It may be remembered.

(Pump control during defrosting)
FIG. 4 shows a flowchart of fluid flow rate 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 drops with respect to the inlet temperature Twi. Therefore, during the defrosting operation, there is a concern that the supply water temperature of the heat source system 100 may decrease and the heat exchanger 8 on the heat medium side may freeze. 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, the decrease in the outlet temperature Two is suppressed when the water flow rate FR is large as compared with the case where 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 rate control of FIG. 4 for the heat source unit 1. First, the operation control means 51 determines whether or not the heat source unit 1 is in the defrosting operation (step ST101). When the defrosting operation is not in progress (step ST101; NO), the operation control means 51 controls so that the water flow rate FR supplied by the fluid pump 20 becomes a normal water flow rate (step ST104). Specifically, the operation control means 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) in response to the control signal. On the other hand, when the operation control means 51 is in the defrosting operation (step ST101; YES), the operation control means 51 notifies the temperature determination means 52. Upon receiving the notification from the operation control means 51, the temperature determination means 52 acquires the information of the inlet temperature Twi from the inlet temperature sensor 16 of the heat source unit 1 and also acquires the first set temperature T1 from the storage means 54. Then, the temperature determining means 52 determines whether or not the acquired inlet temperature Twi is equal to or lower than the first set temperature T1 (step ST102). The first set threshold value is a preset water temperature, and is set to, for example, 30 ° C. here. The temperature determination means 52 notifies the operation control means 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 rotation speed of the fluid pump 20 is increased to the "maximum" (for example, 60 Hz) via the pump control device 21, and the decrease of the outlet temperature Two with respect to the inlet temperature Twi is suppressed. 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 as 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 rate control of steps ST101 to ST104. The operation control means 51 ends the fluid flow rate control when the heating operation is completed.

(Freeze evaporation temperature Tf)
By the way, the increase in the amount of water is effective not only in suppressing the decrease in the outlet temperature Two but also in suppressing the freezing of the heat exchanger 8 on the heat medium side. 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 rises. For example, when the water flow rate FR and the evaporation temperature Te as the cooling capacity of the refrigerant circuit 2 are constant, if the inlet temperature Twi of the water heat medium is low, the outlet temperature Two is also lowered accordingly, so that the state is likely to freeze. Become.

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

Further, the heat exchanger 8 is suppressed from freezing based on the evaporation temperature Te by utilizing 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 do it. 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, in the freeze detection of the heat medium side heat exchanger 8 during the defrosting operation of the air side heat exchanger 5, the defrosting operation is terminated by detecting the decrease in the inlet temperature Twi or the outlet temperature Two as in the conventional case. When controlling, it is necessary to set the freezing detection threshold to a high temperature for safety.

FIG. 7 shows a flowchart of freezing control according to the first embodiment of the present invention. When the inlet temperature Twi drops below a predetermined temperature, the control device 50 detects freezing by comparing the evaporation temperature Te with the freeze 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. 7 for the heat source unit 1. First, the operation control means 51 determines whether or not the heat source unit 1 is in the defrosting operation (step ST111). When the operation control means 51 is in the defrosting operation (step ST111; YES), the operation control means 51 notifies the temperature determination means 52. On the other hand, if the operation control means 51 is not in the defrosting operation (step ST111; NO), the operation control means 51 returns to step 111 and monitors whether the defrosting operation is started during the heating operation. Next, when the temperature determination means 52 receives the notification from the operation control means 51, the temperature information of the inlet temperature Twi is acquired from the inlet temperature sensor 16 of the heat source unit 1, and the second set temperature T2 is acquired from the storage means 54. To do. Then, the 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, and is set to, for example, 15 ° C. here. When the operation control means 51 determines that the inlet temperature Twi is equal to or lower than the second set temperature T2 (step ST112; YES), the temperature determination means 52 notifies the freeze determination means 53. On the other hand, when the inlet temperature Twi is larger than the second set temperature (step ST112; NO), the temperature determining means 52 notifies the operation control means 51. When the operation control means 51 receives the notification from the temperature determination means 52, the defrosting operation is continued (step ST115), while the freeze determination means 53 receives the notification from the temperature determination means 52, the evaporation temperature sensor 14 and the inlet. The temperature information is acquired from the temperature sensor 16. Further, the freeze determination means 53 acquires operation information regarding the water flow rate set in the fluid pump 20 from the operation control means 51. Then, the freezing determination means 53 calculates the freezing evaporation 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 of the storage means 54. Further, the freezing determination means 53 determines whether or not the acquired 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 means 53 to the operation control means 51. When the evaporation temperature Te is equal to or lower than the freeze evaporation temperature Tf (step ST113; YES), the operation control means 51 ends the defrosting operation (step ST114). That is, when the set water flow rate FR and the water heat medium having the inlet temperature Twi pass through the heat medium side heat exchanger 8 having the evaporation temperature Te, the water temperature drops to the extent that freezing occurs at the outlet temperature. In that 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 means 51 determines that the heat exchanger 8 on the heat medium side does not freeze and continues the defrosting operation (step). ST115). The operation control means returns to step ST111 and repeats the freezing control after ending or continuing the defrosting operation in step ST114 or step ST115. The operation control means ends the freezing control when the heating operation is completed.

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 the freezing determination can be made in consideration of the change in the water flow rate FR. The control device 50 can be implemented by using the freezing control shown in FIG. 7 and the flow rate control shown in FIG. 4 in combination.

As described above, in the first embodiment, the heat source system 100 includes a heat source unit 1 that heats and cools the fluid and a control device 50 that controls the heat source unit 1. In the heat source system 100, the heat source unit 1 is a compressor 3. And the fluid fluid flow path switching device 4, the air side heat exchanger 5, the decompression device 7, and the heat medium side heat exchanger 8 are connected via the refrigerant pipe 11, and the hot medium side heat exchanger 8 is used. A fluid pipe 22 through which a fluid that exchanges heat with the refrigerant of the refrigerant circuit 2 flows, a fluid pump 20 provided in the fluid pipe 22 that supplies the fluid to the heat medium side heat exchanger 8, and a heat medium side heat exchanger 8. The control device 50 includes an inlet temperature sensor 16 for measuring the temperature of the inflowing fluid, and the control device 50 during a defrosting operation in which the air side heat exchanger 5 becomes a condenser and the heat medium side heat exchanger 8 becomes an evaporator. The operation control means 51 for controlling the fluid pump 20 is provided so that the flow rate of the fluid supplied to the heat medium side heat exchanger 8 changes according to the fluid temperature Twi measured by the inlet temperature sensor 16.

As a result, regardless of whether the heat source unit 1 constituting the heat source system 100 is composed of a single unit or a plurality of units, the temperature drop of the water heat medium supplied from the heat source system 100 during defrosting is suppressed. To.

Further, the control device 50 further includes a temperature determining means 52 for determining whether or not the measured fluid temperature Twi is lower than the first set temperature T1 during the defrosting operation, and the operation control means 51 is provided with the operation control means 51 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 made larger than the normal flow rate.

From this, 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 heat medium is increased, so that the water heat medium supplied by the heat source system 100 is used. The temperature drop is suppressed. Further, freezing of the heat exchanger 8 on the heat medium side is suppressed.

Further, the heat source unit 1 further includes an evaporation temperature sensor 14 for measuring the evaporation temperature of the refrigerant, and the control device 50 further includes the fluid flow rate FR supplied during the defrosting operation, the measured fluid temperature Twi, and the evaporation. The operation control means 51 includes a freezing determination means 53 for determining whether or not the heat medium side heat exchanger 8 freezes based on the evaporation temperature Te measured by the temperature sensor 14, and the operation control means 51 is a heat medium side heat exchanger. When it is determined that 8 does not freeze, the defrosting operation is continued.

As a result, freezing control is performed in consideration of the difference in the freezing 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. Further, if the freezing control is configured to increase the flow rate to suppress freezing, the defrosting operation is continued even at a lower temperature. Therefore, even though the defrosting is incomplete, it is possible to prevent the defrosting operation from being stopped in order to prevent the heat exchanger 8 on the heat medium side from freezing.

Further, the control device 50 further includes a temperature determining means 52 for determining whether or not the measured fluid temperature Twi is lower than the second set temperature T2 during the defrosting operation, and the freezing determining means 53 is provided during the defrosting operation. When it is determined that the measured fluid temperature Twi is lower than the second set temperature T2, it is determined whether or not the heat exchanger 8 on the heat medium side freezes. From this, the control device 50 can set a threshold value for the temperature of the fluid and use it as a condition for the freezing determination means 53 to start the freezing determination.

Further, the freeze determination means 53 calculates the freeze 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 freeze evaporation temperature Tf. Is determined to freeze, and if the measured evaporation temperature Te is higher than the calculated freeze-evaporation temperature Tf, it is determined not to freeze.

From this, the threshold value (freeze evaporation temperature Tf) is calculated according to the inlet temperature Twi and the water flow rate FR, so that the freezing determination can be made with high accuracy. Therefore, the heat source system 100 can carry out the defrosting operation for a longer time than when the defrosting operation is performed based on the conventional freezing determination, for example, when the inlet temperature Twi is high or the water flow rate FR is large.

Further, the operation control means 51 adjusts the drive frequency of the corresponding fluid pump 20 to change the supplied fluid flow rate FR, and when the supplied fluid flow rate FR is increased, the drive frequency of the fluid pump 20 is increased. When the fluid flow rate FR to be supplied is reduced, the drive frequency of the fluid pump 20 is reduced. From this, if the drive frequency of the fluid pump 20 and the water flow rate FR are synchronized, the control device 50 can change the water flow rate FR in multiple stages by transmitting a control signal according to the target water flow rate. Can be done.

Embodiment 2.
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 side and the downstream side of the heat medium side heat exchangers 8a to 8c. The water heat medium supplied from the hot water storage tank to the heat source system 100 branches into the heat source units 1a to 1c at the confluence on the upstream side, and after being heated or cooled by the heat exchangers 8a to 8c on the heat medium side. It rejoins at the confluence on the downstream side, is sent 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 case where the heat source unit 1a is in the defrosting operation and the remaining heat source units 1b and 1c are not in the defrosting operation among the plurality of heat source units 1a to 1c will be described. To do.

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

(Pump control during defrosting)
In the second embodiment, when the inlet temperature Twi of the heat source unit 1a during the defrosting operation is higher than a predetermined temperature, the control device 50 supplies the fluid pump 20a of the heat source unit 1a to the heat exchanger 8a on the heat medium side. Reduce the water flow rate FRa. As a result, the amount of water sent from the cooled heat medium is suppressed, and the decrease in water temperature sent to the hot water storage tank is suppressed. In the heat source system 100 composed of a plurality of heat source units 1a to 1c, the heat source units 1b and 1c that are not being defrosted can supply hot water, which is lower than that of the heat source system composed of a single heat source unit. The water flow rate FRa of the heat source unit 1a during defrosting 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 rate 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 means 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 means 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, if there is a heat source unit 1a during the defrosting operation (step ST201; YES), the operation control means 51 notifies the temperature determination means 52. Upon receiving the notification from the operation control means 51, the temperature determination means 52 acquires the information of the inlet temperature Twi from the inlet temperature sensor 16a of the heat source unit 1a during defrosting, and also stores the first set temperature T1 from the storage means 54. get. Then, the temperature determining means 52 determines whether or not the acquired inlet temperature Twi is equal to or lower than the first set temperature T1 (step ST202). The first set temperature T1 is a preset water temperature, and is assumed to be set to, for example, 30 ° C. The temperature determination means 52 notifies the operation control means 51 of the determination result. The operation control means 51 receives a 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 ST202; YES), the operation control means 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 maximized (for example, 60 Hz). Further, 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 rate (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 means 51 sets the water flow rate FRa of the heat source unit 1a during defrosting 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 and FRc of the heat source units 1b and 1c that have not been defrosted (step ST206). Specifically, the operation control means 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 then returns to step ST201 to repeat the fluid flow rate control. The operation control means 51 ends the fluid flow rate control when the heating operation is completed.

Therefore, when the inlet temperature Twi is higher than the first set temperature T1, the amount of supplied water reduced by the heat source unit 1a during defrosting increases the water flow rates FRb and FRc of the heat source units 1b and 1c not being defrosted. The 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 that are not in the defrosting operation, the amount of water becomes larger than usual, so that the rise in the outlet temperature Two is suppressed, and there is a concern that the water temperature becomes lower than the target water temperature. However, in the configuration in which the frequency of the compressor 3 is controlled, the compressor frequencies of the heat source units 1b and 1c that are not being defrosted are accelerated and the heating capacity is increased. The water temperature drop is backed up.

In step ST204, 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 rate, 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. Since the heat source unit 1a also has the maximum water flow rate in step ST203, there is a concern that the total amount of water will increase when the heat source units 1b and 1c are operated at a large water flow rate. Therefore, the operation control means 51 may be configured to reduce the water flow rates FRb and FRc of the heat source units 1b and 1c 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 means 51 has a plurality of heat sources. When 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 first. When it is determined that the temperature is higher than the set temperature T1, the fluid flow rate FRa supplied by the first heat source unit 1a is made smaller than the normal flow rate, and the fluid flow rates FRb and FRc supplied by the second heat source units 1b and 1c are usually set. It is more than the flow rate.

As a result, since the heat source system 100 includes a plurality of heat source units 1a to 1c, when the fluid temperature Twi is higher than the first set temperature T1, the flow rate of cooling by the heat source unit 1a during defrosting is reduced, and the other The heat source units 1b and 1c of the above can back up the supply water amount and supply temperature as a whole.

Further, each heat source unit 1a to 1c further includes outlet temperature sensors 17a to 17c for measuring the outlet temperature of the fluid flowing out from the heat medium side heat exchangers 8a to 8c, and the operation control means 51 includes a second heat source unit 1b. The frequency of the compressor 3 of the second heat source units 1b and 1c is adjusted so that the outlet temperature Two measured in 1c and 1c approaches the set target temperature.

As a result, the heating capacity is increased even when the water flow rates FRb and FRc of the other heat source units 1b and 1c are large, so that even if there is a heat source unit 1a during defrosting, the water temperature supplied from the heat source system 100 The decrease is suppressed.

The embodiment of the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the heat source system 100 composed of a plurality of heat source units 1a to 1c, a case where one control device 50 controls a plurality of heat source units 1a to 1c has been described. For example, the respective heat source units 1a to 1c have been described. 1c may be configured to include control devices 50a to 50c. In this case, for example, one control device 50a acquires operation information and the like from the other heat source units 1b and 1c, performs fluid flow rate control in FIG. 9, and changes the water flow rate to the other control devices 50b and 50c. Just notify.

Further, the fluid pump 20 may be configured by a pump that obtains kinetic energy to circulate the fluid by reciprocating motion instead of rotary motion, as long as the water flow rate FR of the water heat medium to be sent out can be changed in a plurality of steps.

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

Further, although the case where the load side device is an air conditioner has been described, for example, a floor heating system or a hot water supply system may be used. In addition, a storage tower tank is provided between the heat source system and the load-side equipment so that the water heat medium circulates between the heat source system and the storage tower tank and between the storage tower tank and the load-side equipment. You may.

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

Claims (2)

In a heat source system including a heat source unit that heats and cools a fluid and a control device that controls the heat source unit.
The heat source unit is
A refrigerant circuit in which a compressor, a refrigerant flow path switching device, an air side heat exchanger, a decompression device, and a heat medium side heat exchanger are connected via a refrigerant pipe.
A fluid pipe through which the fluid that is heat-exchanged with the refrigerant in the refrigerant circuit by the heat medium side heat exchanger flows.
A fluid pump provided in the fluid pipe and supplying the fluid to the heat medium side heat exchanger.
An inlet temperature sensor that measures the temperature of the fluid flowing into the heat exchanger on the heat medium side, and an inlet temperature sensor.
A evaporation temperature sensor for measuring the evaporation temperature of the refrigerant is provided.
The control device is
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. An operation control means for controlling the fluid pump so as to change according to the fluid temperature.
Freezing determination means for determining whether or not the heat exchanger on the heat medium side freezes based on the supplied fluid flow rate, the measured fluid temperature, and the measured evaporation temperature during the defrosting operation. When,
A temperature determining means for determining whether or not the measured fluid temperature is lower than the second set temperature during the defrosting operation is provided.
The freezing determination means determines whether or not the heat exchanger on the heat medium side freezes when the measured fluid temperature is determined to be lower than the second set temperature during the defrosting operation.
The freezing 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. Judgment is made, and when the measured evaporation temperature is higher than the calculated freeze evaporation temperature, it is determined that the product does not freeze.
The operation control means is a heat source system that continues the defrosting operation when it is determined that the heat exchanger on the heat medium side does not freeze. 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 the supplied fluid flow rate is increased. The heat source system according to claim 1, wherein the drive frequency of the fluid pump is reduced when the flow rate of the supplied fluid is reduced.

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