JP2021156552A - Heating system - Google Patents

Abstract

To provide a heating system suppressed in generation of dew condensation on a heat exchanger of a combustion heat source machine in reverse cycle defrosting.SOLUTION: In a heating system in which a combustion heat source machine 3 is disposed at a downstream side of a heat pump-type heat source machine 2 with respect to flow of a refrigerant circulated in a circulation circuit 25, when a prescribed defrost start condition is established in performing a heating operation of a heating terminal 4 by heating a heat medium by the heat pump-type heat source machine 2, a switch valve 6 is switched so that a flowing direction of the refrigerant becomes opposite to the flowing direction of the refrigerant in the heating operation, so as to execute reverse cycle defrosting for melting frost generated on the air heat exchanger 10 by supplying the refrigerant discharged from the compressor 5 to the air heat exchanger 10, and the combustion heat source machine 3 is operated to further increase a flow rate of the refrigerant in executing the reverse cycle defrosting in comparison with the flow rate of the refrigerant in the heating operation.SELECTED DRAWING: Figure 2

Description

The present invention relates to a heating system using a plurality of heat sources.

Conventionally, this type of heat pump has a heat pump type heat source machine having a compressor, a liquid refrigerant heat exchanger, a four-way valve, an expansion valve, and an air heat exchanger, and a combustion heat source machine, and burns on the downstream side of the heat pump type heat source machine. In some cases in which a heat source machine is provided, a heating operation is performed by a heating terminal using a heat medium heated by a heat pump type heat source machine or a combustion heat source machine. (See, for example, Patent Document 1.)

Japanese Unexamined Patent Publication No. 2016-118340

By the way, in this conventional one, when the heat medium is heated by the heat pump type heat source machine and the heating operation is performed by the heating terminal, if the frost formation on the air heat exchanger progresses, the defrosting of the air heat exchanger is performed. It will be executed.

During this defrosting, when defrosting is performed with the four-way valve switched so that the flow direction of the refrigerant is opposite to the flow direction of the refrigerant during the heating operation, so-called reverse cycle defrosting is executed, the heating operation is performed. The air heat exchanger, which sometimes functioned as an evaporator, functions as a condenser, and the liquid refrigerant heat exchanger, which sometimes functioned as a condenser during the heating operation, functions as an evaporator.

Then, at the time of reverse cycle defrosting, a low temperature refrigerant flows through the liquid refrigerant heat exchanger, and the heat medium flowing through the liquid refrigerant heat exchanger also becomes low temperature due to heat exchange with the refrigerant. Here, during reverse cycle defrosting, when the combustion heat source machine operates as a backup to supply the heated heat medium to the heating terminal, the heat medium that flows out of the liquid refrigerant heat exchanger and flows into the combustion heat source machine. In the heat exchanger of the combustion heat source machine, the combustion gas is rapidly cooled and dew condensation occurs on the heat exchange surface, and if the heat exchanger continues to have dew condensation, the heat exchanger will rot. , May cause damage.

In order to solve the above problems, in the first aspect of the present invention, a heating terminal, a circulation circuit having a circulation pump for circulating a heat medium to the heating terminal, a compressor for compressing a refrigerant, and the heat medium are used. A heat pump type heat source machine having a liquid refrigerant heat exchanger for heat exchange with the refrigerant, a switching valve, an expansion valve, and an air heat exchanger to heat the heat medium circulating in the circulation circuit, and the above. A combustion heat source machine for heating the heat medium circulating in the circulation circuit and a control device are provided, and the combustion heat source machine is located on the downstream side of the heat pump type heat source machine with respect to the flow of the heat medium circulating in the circulation circuit. In the heating system arranged in the above, the control device determines that the predetermined defrosting start condition is satisfied when the heat medium is heated by the heat pump type heat source machine and the heating operation is performed by the heating terminal. In this case, the switching valve is switched so that the flow direction of the refrigerant is opposite to the flow direction of the refrigerant during the heating operation, and the refrigerant discharged from the compressor is supplied to the air heat exchanger. The reverse cycle defrosting that melts the frost generated in the air heat exchanger is executed, the combustion heat source machine is operated, and the flow rate of the heat medium during the reverse cycle defrosting execution is set to the heat during the heating operation. It was decided to increase the flow rate of the medium.

According to claim 1 of the present invention, by making the flow rate of the heat medium during the reverse cycle defrosting execution larger than the flow rate of the heat medium during the heating operation, the heat medium passes through the liquid refrigerant heat exchanger during the reverse cycle defrosting execution. As a result, the degree of decrease in the temperature of the heat medium flowing into the combustion heat source machine can be reduced, and the amount of heat absorbed from the heat medium to the refrigerant by the liquid refrigerant heat exchanger increases, which is used for defrosting the air heat exchanger. The amount of heat generated can be increased, the defrosting time can be shortened, the time for the low-temperature heat medium to flow into the combustion heat source machine can be shortened, and the occurrence of dew condensation on the heat exchanger of the combustion heat source machine during operation can be suppressed. .. By suppressing the occurrence of dew condensation, it is possible to suppress corrosion and damage to the heat exchanger of the combustion heat source machine.

The schematic block diagram of the heating system of one Embodiment of this invention. A time chart explaining the operation during defrosting operation.

Next, the configuration of the heating system 1 according to the embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the heating system 1 mainly includes a heat pump type heat source machine 2, a hot water storage type combustion heat source machine 3 as a combustion heat source machine, and a heating terminal 4. The heating system 1 uses a heat medium (for example, a circulating liquid such as water or antifreeze) heated by at least one of the heat pump type heat source machine 2 and the hot water storage type combustion heat source machine 3 and heat medium at the heating terminal 4. By radiating heat from the air-conditioned space, the heating operation for warming the air-conditioned space in which the heating terminal 4 is installed is performed.

The heat pump type heat source machine 2 is a heat source machine for heating a heat medium, and in the housing thereof, a compressor 5 having a variable rotation speed for compressing the refrigerant, a four-way valve 6 as a switching valve, and heat between the refrigerant and the heat medium. As a liquid refrigerant heat exchanger 7 as a load side heat exchanger to be exchanged, an expansion valve 8 as a decompressor, and a heat source side heat exchanger to exchange heat with the air (outside air) sent by the operation of the outdoor fan 9. It has an air heat exchanger 10 and is connected in a ring shape by a refrigerant pipe 11 to form a heat pump circuit 12 in which a refrigerant circulates.

In the heat pump type heat source machine 2, 13 is an outside air temperature sensor that detects the outside air temperature, and 14 is provided in the refrigerant pipe 11 from the expansion valve 8 to the air heat exchanger 10 to detect the temperature of the refrigerant flowing out from the expansion valve 8. The refrigerant temperature sensor 15 is provided in the refrigerant pipe 11 from the air heat exchanger 10 to the compressor 5, and is an evaporative refrigerant temperature sensor that detects the temperature of the refrigerant flowing out of the air heat exchanger 10.

Further, the liquid refrigerant heat exchanger 7 is composed of, for example, a plate type heat exchanger, and in the plate type heat exchanger, a plurality of heat transfer plates are laminated to flow a refrigerant flow path and a heat medium through which the refrigerant flows. The heat medium flow paths to be used are alternately formed with each heat transfer plate as a boundary. As the refrigerant that circulates in the heat pump circuit 12, any refrigerant such as an HFC refrigerant or a carbon dioxide refrigerant can be used.

The four-way valve 6 provided in the refrigerant pipe 11 has a function of switching the flow direction of the refrigerant in the heat pump circuit 12, and uses the refrigerant discharged from the compressor 5 as the liquid refrigerant heat exchanger 7, the expansion valve 8, and the air. A state in which the heat exchanger 10 is circulated in this order to form a flow path for returning to the compressor 5 (state during heating operation), and a state in which the refrigerant discharged from the compressor 5 is passed through the air heat exchanger 10, the expansion valve 8, and the liquid. It is possible to switch to a state in which the refrigerant heat exchanger 7 is circulated in this order and a flow path for returning to the compressor 5 is formed (a state during the defrosting operation).

The hot water storage type combustion heat source machine 3 is a heat source machine for heating a heat medium, and inside the housing, combustion is performed by receiving combustion air from a blower fan 16 to burn fuel (gas, kerosene, etc.). The burner 17 as a container, the hot water storage type heat exchanger 18 that recovers heat from the combustion gas generated by the combustion of the burner 17 and heats the heat medium, and the hot water storage type heat exchanger 18 adjacent above the hot water storage type heat exchanger 18. It has an exhaust chamber 19 for collecting the combustion gas after passing through the exhaust chamber 19 and an exhaust pipe 20 for discharging the combustion gas after passing through the exhaust chamber 19 to the outside of the machine.

The hot water storage type heat exchanger 18 has a cylindrical and small-capacity storage can body 21 that stores a certain amount (4L to 10L) of heat medium inside, and a burner 17 formed inside the lower part of the storage can body 21 to burn. It is composed of a combustion chamber 22 to be performed, and a plurality of smoke tubes 23 that communicate the combustion chamber 22 and the exhaust chamber 19 and pass the combustion gas generated by the combustion of the burner 17. Reference numeral 24 denotes a first heat medium temperature sensor as a first temperature detecting means for detecting the temperature of the heat medium in the storage can body 21. The first heat medium temperature sensor 24 detects the temperature of the heat medium flowing out of the storage can body 21 and flowing into the heating terminal 4 even if it is not directly installed in the storage can body 21. You may.

Reference numeral 25 denotes a circulation circuit that circulates the heat medium to the heating terminal 4, and the circulation circuit 25 guides the heat medium flowing out from the heating terminal 4 to the heat medium flow path of the liquid refrigerant heat exchanger 7 of the heat pump type heat source machine 2. A second heat medium pipe that guides the heat medium flowing out from the heat medium pipe 26 and the liquid refrigerant heat exchanger 7 of the heat pump type heat source machine 2 to the hot water storage type heat exchanger 18 (storage can body 21) of the hot water storage type combustion heat source machine 3. It has 27 and a third heat medium pipe 28 that guides the heat medium flowing out from the hot water storage type heat exchanger 18 (storage can body 21) of the hot water storage type combustion heat source machine 3 to the heating terminal 4, and the circulation circuit 25 is a heat pump. The type heat source machine 2, the hot water storage type combustion heat source machine 3, and the heating terminal 4 are connected by the first heat medium pipe 26, the second heat medium pipe 27, and the third heat medium pipe 28, and are formed so that the heat medium circulates. Is to be done. The hot water storage type combustion heat source machine 3 is arranged on the downstream side of the heat pump type heat source machine 2 with respect to the flow of the heat medium circulating in the circulation circuit 25.

The first heat medium pipe 26 is provided with a circulation pump 29 that circulates the heat medium in the circulation circuit 25, and is provided with a heat pump side systurn 30 that stores the heat medium and adjusts the pressure of the circulation circuit 25. In the present embodiment, the circulation pump 29 is provided in the heat pump type heat source machine 2, but the circulation pump 29 may be provided in the hot water storage type combustion heat source machine 3, and in the heat pump type heat source machine 2 and in the heat pump type heat source machine 2. One may be provided in each of the hot water storage type combustion heat source machines 3.

The second heat medium pipe 27 detects the temperature of the heat medium that flows out of the liquid refrigerant heat exchanger 7 of the heat pump type heat source machine 2 and flows into the hot water storage type heat exchanger 18 of the hot water storage type combustion heat source machine 3. A second heat medium temperature sensor 31 is provided as a temperature detecting means.

The third heat medium pipe 28 is provided with a combustion side systurn 32 that stores the heat medium and adjusts the pressure of the circulation circuit 25.

Further, each of the third heat medium pipes 28 branched for each heating terminal 4 is provided with a thermal valve 33 that controls the supply of the heat medium to the heating terminal 4 by opening and closing the thermal valve 33. The opening and closing is controlled so that the temperature of the air-conditioned space (indoor) in which the heating terminal 4 is installed becomes a predetermined temperature. As the heating terminal 4, any terminal such as a floor heating panel or a radiator can be used, and although two are provided in FIG. 1, one may be one, or three or more may be used, and the quantity may be three or more. And specifications are not particularly limited.

Reference numeral 34 denotes a remote controller for instructing the operation of the heating system 1, and the remote controller 34 is a temperature setting for setting an operation switch for instructing the start or stop of the heating operation by the heating terminal 4 and a target temperature of the heat medium for circulating the circulation circuit 25. It is equipped with a switch, a display unit, and the like.

Reference numeral 35 denotes a storage means (ROM, non-volatile memory, etc.) for storing various data and programs, and a control means for performing arithmetic / control processing, and the heat pump side as a control device for controlling the operation of the heat pump type heat source machine 2. The heat pump side control device 35 receives a signal from the remote control 34 and a signal from the outside air temperature sensor 13 and the second heat medium temperature sensor 31 to control the operation of actuators such as the compressor 5 and the circulation pump 29. At the same time, it is communicably connected to the combustion side control device 36 of the hot water storage type combustion heat source machine 3 described later, and signals such as operation instructions can be exchanged with the combustion side control device 36.

Reference numeral 36 denotes a storage means (ROM, non-volatile memory, etc.) for storing various data and programs, and a control means for performing calculation / control processing, and combustion as a control device for controlling the operation of the hot water storage type combustion heat source machine 3. It is a side control device, and the combustion side control device 36 receives a signal from the first heat medium temperature sensor 24, controls the operation of the blower fan 16 and the burner 17, and is connected to the heaton side control device 35 so as to be communicable. Is what you are doing.

Next, the operation during the heating operation in the heating system 1 of this embodiment will be described. The heating operation for generating the high-temperature heat medium supplied to the heating terminal 4 is performed by operating either the heat pump type heat source machine 2 or the hot water storage type combustion heat source machine 3 independently, or the heat pump type heat source machine 2 and In some cases, both of the hot water storage type combustion heat source machine 3 are operated.

First, a case where only the heat pump type heat source machine 2 is operated to perform the heating operation will be described. When the remote control 34 gives an instruction to heat the room as an air-conditioned space by the heating terminal 4, and the heat pump type heat source machine 2 operates. , The heat pump side control device 35 switches the flow path so that the four-way valve 6 is in the state during the heating operation, drives the compressor 5, the expansion valve 8, the outdoor fan 9, and the circulation pump 29 to start the heating operation. Let me. At this time, the thermal valve 33 corresponding to the heating terminal 4 in which the heating operation is performed is also opened.

During the heating operation, in the heat pump circuit 12, a high-temperature, high-pressure gaseous refrigerant compressed by the compressor 5 is discharged from the compressor 5, and the refrigerant is circulated by the liquid refrigerant heat exchanger 7 functioning as a condenser. It exchanges heat with the heat medium flowing through the circuit 25, releases heat to the heat medium, and changes to a high-pressure refrigerant in a gas-liquid mixed state while heating. Then, the refrigerant in this state is depressurized by the expansion valve 8 to become a low-pressure refrigerant and easily evaporate, and in the air heat exchanger 10 functioning as an evaporator, heat exchange with the outside air sent by the operation of the outdoor fan 9. It absorbs heat from the outside air to become a low-temperature, low-pressure gaseous refrigerant, and returns to the compressor 5 again.

In the circulation circuit 25, the low-temperature heat medium that has flowed into the liquid refrigerant heat exchanger 7 by driving the circulation pump 29 driven at a constant rotation speed exchanges heat with the refrigerant in the liquid refrigerant heat exchanger 7 that functions as a condenser. After being heated, it passes through the hot water storage type heat exchanger 18 of the hot water storage type combustion heat source machine 3 without being heated, and then is supplied to the heating terminal 4 and used for indoor heating, and is distributed through the heating terminal 4. The heat medium that has been dissipated and whose temperature has dropped is returned to the liquid refrigerant heat exchanger 7. At this time, the heat medium heated by the heat pump type heat source machine 2 is stored in the hot water storage type heat exchanger 18 (storage can body 21) of the hot water storage type combustion heat source machine 3, and the hot water storage type heat exchanger 18 (storage can body 21) is stored. The temperature of the heat medium in 21) is maintained at substantially the same temperature as the target temperature as long as the heat pump type heat source machine 2 is operating.

During the heating operation, the heat pump side control device 35 controls the rotation speed of the compressor 5 according to the detected value of the second heat medium temperature sensor 31. Here, the number of revolutions of the compressor 5 is such that the temperature of the heat medium detected by the second heat medium temperature sensor 31 becomes a target temperature determined based on, for example, a set temperature set by the user on the remote controller 34. To control.

Further, the heat pump side control device 35 controls the valve opening degree of the expansion valve 8 according to the discharge temperature of the refrigerant discharged from the compressor 5. Here, the valve opening degree of the expansion valve 8 is controlled so that the discharge temperature of the refrigerant discharged from the compressor 5 becomes, for example, the control target refrigerant discharge temperature corresponding to the set temperature of the remote controller 34.

Further, the heaton side control device 35 controls the rotation speed of the outdoor fan 9 according to the outside air temperature detected by the outside air temperature sensor 13.

Next, a case where only the hot water storage type combustion heat source machine 3 is operated to perform the heating operation will be described. The remote control 34 gives an instruction to heat the room as an air-conditioned space by the heating terminal 4, and the heating is instructed via the heat pump side control device 35. When the combustion side control device 36 receives the instruction and the hot water storage type combustion heat source machine 3 operates, the combustion side control device 36 drives the blower fan 16 and the fuel pump (not shown), and the burner 17 operates. Combustion is performed, and the circulation pump 29 is driven to start the heating operation. At this time, the thermal valve 33 corresponding to the heating terminal 4 in which the heating operation is performed is also opened.

During the heating operation, the combustion side control device 36 sets the temperature of the heat medium in the storage can body 21 detected by the first heat medium temperature sensor 24 to a target temperature determined based on the set temperature set by the remote control 34. It is controlled by executing or stopping the combustion of the burner 17 and adjusting the combustion amount so that the combustion amount of the burner 17 is controlled so that the temperature of the heat medium quickly rises to the target temperature at the start of the heating operation. It is possible to set the upper limit combustion amount set in advance, and then gradually reduce the combustion amount of the burner 17 as the temperature of the heat medium approaches the target temperature to maintain the temperature of the heat medium at the target temperature. For example, the combustion amount is reduced to the preset lower limit combustion amount to perform combustion, and when the temperature of the heat medium reaches the combustion off temperature which is a predetermined temperature higher than the target temperature, the combustion of the burner 17 is stopped and the temperature of the heat medium is the target. When the combustion on temperature reaches a predetermined temperature lower than the temperature or the target temperature, the combustion of the burner 17 is restarted, and the combustion amount is appropriately controlled so that the temperature of the heat medium in the storage can body 21 approaches the target temperature.

In the circulation circuit 25, the low-temperature heat medium flowing out of the heating terminal 4 due to the drive of the circulation pump 29 driven at a constant rotation speed passes through the liquid refrigerant heat exchanger 7 of the heat pump type heat source machine 2 without being heated. Then, after being heated by exchanging heat with the combustion gas in the hot water storage type heat exchanger 18 of the hot water storage type combustion heat source machine 3, it is supplied to the heating terminal 4 and used for indoor heating, and when the heating terminal 4 is distributed. The heat medium that has been dissipated and the temperature has dropped passes through the liquid refrigerant heat exchanger 7 without being heated again and returns to the hot water storage type heat exchanger 18.

Subsequently, the heating load is large, and the output is insufficient when either the heat pump type heat source machine 2 or the hot water storage type combustion heat source machine 3 is operated. Therefore, both the heat pump type heat source machine 2 and the hot water storage type combustion heat source machine 3 are operated. Explaining the case of performing the heating operation, when the heating operation is performed by operating both the heat pump type heat source machine 2 and the hot water storage type combustion heat source machine 3, it is detected by the first heat medium temperature sensor 24 of the hot water storage type combustion heat source machine 3. The heat pump side control device 35 and the combustion side control device 36 cooperate with each other as necessary so that the temperature of the heat medium to be generated becomes a target temperature determined based on the set temperature set by the remote control 34. , The number of rotations of the compressor 5 is controlled and the burner 17 is controlled.

In the circulation circuit 25, the low-temperature heat medium flowing into the liquid refrigerant heat exchanger 7 by driving the circulation pump 29 driven at a constant rotation speed is heated by heat exchange with the refrigerant in the liquid refrigerant heat exchanger 7. Later, in the hot water storage type heat exchanger 18 of the hot water storage type combustion heat source machine 3, heat is exchanged with the combustion gas and further heated, and the heated heat medium is then supplied to the heating terminal 4 and used for indoor heating. The heat medium whose temperature has dropped due to heat radiated when flowing through the heating terminal 4 returns to the liquid refrigerant heat exchanger 7 again.

Here, regarding the heating operation performed by operating either the heat pump type heat source machine 2 or the hot water storage type combustion heat source machine 3, the determination for determining which heat source machine is to be operated with priority is the outside air temperature. It is performed based on the cost for operating the heat source machine (electricity cost for the heat pump type heat source machine 2 and fuel cost for the hot water storage type combustion heat source machine 3). Specifically, the operating costs of the heat pump type heat source machine 2 and the hot water storage type combustion heat source machine 3 are compared, and the heat source machine having the lowest operating cost is used as the heat source machine for preferential operation, and the other is used as the heat source machine for auxiliary operation. The operating cost of the heat pump type heat source machine 2 is calculated based on the thermal efficiency (coefficient of performance) according to the outside air temperature and the electricity cost that changes according to the time zone, and the operating cost of the hot water storage type combustion heat source machine 3 is the thermal efficiency. It is calculated based on the fuel cost.

For example, when the outside air temperature fluctuates (the outside air temperature drops) during the heating operation in which only the heat pump type heat source machine 2 is operated, the heat source for heating the heat medium is changed from the heat pump type heat source machine 2 to the hot water storage type combustion heat source machine. When the outside air temperature fluctuates (the outside air temperature rises) during the heating operation in which only the hot water storage type combustion heat source machine 3 is operated, the hot water storage type combustion heat source machine 3 is switched to the heat pump type heat source machine 2. It is a thing.

Next, in the present embodiment, a case where the defrosting operation is performed during the heating operation in which only the heat pump type heat source machine 2 is operated will be described with reference to the time chart of FIG. In FIG. 2, the time course of the flow rate of the heat medium circulating in the circulation circuit 25 of the present embodiment and the comparative example, the time course of the rotation speed of the circulation pump 29, and the temperature of the heat medium flowing into the hot water storage type combustion heat source machine 3 ( FIG. 2 shows the time course of the combustion heat source machine inflow heat medium temperature).

First, in the present embodiment, the heating operation is performed by operating only the heat pump type heat source machine 2 until the time t1, and the target temperature of the heat medium supplied to the heating terminal 4 is set to 45 ° C. The heat pump side control device 35 controls the compressor 5 and the like so that the temperature of the heat medium detected by the second heat medium temperature sensor 31 becomes the target temperature. At this time, in the circulation circuit 25 (second heat medium pipe 27, storage can body 21, third heat medium pipe 28) from the outlet of the liquid refrigerant heat exchanger 7 of the heat pump type heat source machine 2 to the inflow port of the heating terminal 4. The temperature of the heat medium is substantially the same as the target temperature (45 ° C.).

During the heating operation, if the outside air temperature is low, the air heat exchanger 10 gradually frosts. When a predetermined defrosting start condition is satisfied during the heating operation, for example, the outside air temperature detected by the outside air temperature sensor 13 and the refrigerant temperature on the outlet side of the air heat exchanger 10 detected by the evaporated refrigerant temperature sensor 15. When the temperature difference of the above exceeds a predetermined value, the execution of the defrosting operation for melting the frost of the air heat exchanger 10 is started.

Explaining the defrosting operation, the defrosting operation of the present embodiment is a mode in which the refrigerant is circulated in the direction opposite to the flow direction of the refrigerant during the heating operation (so-called reverse cycle defrosting), and is generated in the air heat exchanger 10. It melts the frost that has formed. When the reverse cycle defrosting is executed, the air heat exchanger 10 that functions as an evaporator during the heating operation functions as a condenser, and the liquid refrigerant heat exchanger 7 that functions as a condenser during the heating operation It will function as an evaporator. The drive of the circulation pump 29 is continued even during the reverse cycle defrosting.

Returning to FIG. 2, when the heat pump side control device 35 determines that the predetermined defrosting start condition is satisfied at time t1, the flow direction of the refrigerant in the four-way valve 6 is opposite to the flow direction of the refrigerant during the heating operation. The refrigerant discharged from the compressor 5 is supplied to the air heat exchanger 10 to perform reverse cycle defrosting to melt the frost generated in the air heat exchanger 10.

At this time, the heat pump side control device 35 instructs the combustion side control device 36 to operate the hot water storage type combustion heat source machine 3 as a backup so that the heating operation by the heating terminal 4 is continued, and the hot water storage type combustion heat source machine 3 is used. The heat medium is heated and supplied to the heating terminal 4. Further, the heat pump side control device 35 sets the rotation speed of the circulation pump 29 to a rotation speed (4000 rpm in this case) higher than the rotation speed in the heating operation (3000 rpm in this case) at the time of executing the reverse cycle defrosting to perform reverse cycle defrosting. The flow rate of the heat medium flowing through the circulation circuit 25 during frost execution (here, 6 L / min) is set to be larger than the flow rate of the heat medium flowing through the circulation circuit 25 during the heating operation (here, 5 L / min).

On the other hand, in the comparative example, the rotation speed of the circulation pump 29 during the reverse cycle defrosting is the same as the rotation speed of the circulation pump 29 during the heating operation (here, 3000 rpm), and the flow rate of the heat medium flowing through the circulation circuit 25 is also opposite. The same flow rate (here, 5 L / min) is used during cycle defrosting and heating operation.

Here, the temperature transition of the heat medium flowing into the hot water storage type combustion heat source machine 3 during the reverse cycle defrosting of the present embodiment and the time t1 to t3 during the reverse cycle defrosting of the comparative example. Comparing with the temperature transition of the heat medium flowing into the hot water storage type combustion heat source machine 3, the temperature of the heat medium is gradually decreasing in both cases. This is because the liquid refrigerant heat exchanger 7 functions as an evaporator due to reverse cycle defrosting, and as the low temperature refrigerant flows through the liquid refrigerant heat exchanger 7, the heat medium flowing through the liquid refrigerant heat exchanger 7 also becomes a refrigerant. This is because the temperature becomes low due to heat exchange with.

Looking at the present embodiment with reference to the comparative example, the temperature of the heat medium of the present embodiment changes to a higher temperature than the temperature of the heat medium of the comparative example at the time of reverse cycle defrosting, and the minimum temperature of the heat medium is observed. However, the temperature in this embodiment (24 ° C.) is higher than that in the comparative example (19 ° C.). In the present embodiment, the flow rate of the heat medium is increased by increasing the rotation speed of the circulation pump 29 during the reverse cycle defrosting as compared with the heating operation. Then, in the liquid refrigerant heat exchanger 7, the flow of the heat medium is faster in the present embodiment than in the comparative example, and the temperature of the heat medium after passing through the liquid refrigerant heat exchanger 7 is higher (in the comparative example). The heat medium temperature after passing through the liquid refrigerant heat exchanger 7 <relationship between the heat medium temperature after passing through the liquid refrigerant heat exchanger 7 in the present embodiment), that is, the flow rate of the heat medium as in the present embodiment. It means that the temperature of the heat medium after passing through the liquid refrigerant heat exchanger 7 does not decrease when the amount of heat flows faster than when the amount of heat flows slowly as in the comparative example. Therefore, if the flow rate of the heat medium during the reverse cycle defrosting is larger than the flow rate of the heat medium during the heating operation as in the present embodiment, the hot water is stored through the liquid refrigerant heat exchanger 7 during the reverse cycle defrosting. The degree of decrease in the temperature of the heat medium flowing into the hot water storage type combustion heat source machine 3 can be reduced, and the occurrence of dew condensation on the hot water storage type heat exchanger 18 of the hot water storage type combustion heat source machine 3 can be suppressed.

Further, looking at the present embodiment with reference to the comparative example, the defrosting time (time t1 to t2) of the present embodiment is longer than the defrosting time (time t1 to t3) of the comparative example at the time of reverse cycle defrosting. Is getting shorter. In the present embodiment, the flow rate of the heat medium is increased by increasing the rotation speed of the circulation pump 29 during the reverse cycle defrosting as compared with the heating operation. When the flow rate of the heat medium increases, the heat transfer rate to the refrigerant increases in the liquid refrigerant heat exchanger 7, and the amount of heat absorbed from the heat medium to the refrigerant increases, so that it is used for defrosting the air heat exchanger 10. The amount of heat generated increases and the defrosting time shortens. Therefore, as in the present embodiment, if the flow rate of the heat medium (6 L / min) during the reverse cycle defrosting execution is larger than the flow rate (5 L / min) of the heat medium during the heating operation, the defrosting time is shortened. Therefore, the time for the low-temperature heat medium to flow into the hot water storage type combustion heat source machine 3 can be shortened, and the occurrence of dew condensation in the hot water storage type heat exchanger 18 of the hot water storage type combustion heat source machine 3 can be suppressed.

Then, at the time t2 of the present embodiment, the heat pump side control device 35 ends the reverse cycle defrosting when it is determined that the predetermined defrosting end condition is satisfied. The defrosting end condition is, for example, that the temperature of the refrigerant detected by the refrigerant temperature sensor 14 passing through the air heat exchanger 10 and heading toward the expansion valve 8 is a preset defrosting end temperature (for example, 5 ° C.). Is to reach.

When the reverse cycle defrosting is completed, the heat pump side control device 35 switches the four-way valve 6 to the state during the heating operation, returns the rotation speed of the circulation pump 29 to the rotation speed during the heating operation (3000 rpm), and at the same time, the combustion side. An instruction to stop the operation of the hot water storage type combustion heat source machine 3 is sent to the control device 36, the operation of the hot water storage type combustion heat source machine 3 is stopped, and only the heat pump type heat source machine 2 is operated to restart the heating operation.

In the above embodiment, the dew condensation of the hot water storage type heat exchanger 18 of the hot water storage type combustion heat source machine 3 at the time of reverse cycle defrosting is mentioned as a problem, but the problem of this dew condensation is limited to the hot water storage type combustion heat source machine 3. It is not something that can be done. Even when the instantaneous combustion heat source machine is applied instead of the hot water storage type combustion heat source machine 3, there is a problem that the fin tube type heat exchanger of the instantaneous combustion heat source machine condenses. In order to suppress dew condensation, the rotation speed of the circulation pump 29 during the reverse cycle defrosting may be higher than that during the heating operation to increase the flow rate of the heat medium, as in the present embodiment described above. ..

Further, in the present embodiment, the case where the heat pump type heat source machine 2 performs reverse cycle defrosting during the heating operation in which only the heat pump type heat source machine 2 is operated has been described as an example, but the heat pump type heat source machine 2 and the hot water storage The heat pump type heat source machine 2 may perform reverse cycle defrosting during the heating operation by operating both of the type combustion heat source machines 3, and even in that case, the operation performed during the reverse cycle defrosting is performed. Similar to the operation of the present embodiment described above, the hot water storage type combustion heat source machine 3 is operated to increase the rotation speed of the circulation pump 29 to be higher than that during the heating operation to increase the flow rate of the heat medium.

As described above, the combustion heat source machine 3 (in this embodiment, the hot water storage type combustion heat source machine 3) is arranged on the downstream side of the heat pump type heat source machine 2 with respect to the flow of the heat medium circulating in the circulation circuit 25. In the heating system 1, when the heat medium is heated by the heat pump type heat source machine 2 and the heating operation is performed by the heating terminal 4, the heaton side control device 35 determines that the predetermined defrosting start condition is satisfied. The four-way valve 6 is switched so that the flow direction of the refrigerant is opposite to the flow direction of the refrigerant during the heating operation, and the refrigerant discharged from the compressor 5 is supplied to the air heat exchanger 10 to the air heat exchanger 10. In addition to executing reverse cycle defrosting to melt the generated frost, the combustion heat source machine 3 is operated, the rotation speed of the circulation pump 29 is further increased, and the flow rate of the heat medium flowing through the circulation circuit 25 is heated when the reverse cycle defrosting is executed. By making the flow rate of the heat medium larger than that during operation, it is possible to reduce the degree of decrease in the temperature of the heat medium that passes through the liquid refrigerant heat exchanger 7 and flows into the combustion heat source machine 3 during reverse cycle defrosting. , The amount of heat absorbed from the heat medium to the refrigerant by the liquid refrigerant heat exchanger 7 increases, the amount of heat used for defrosting the air heat exchanger 10 increases, the defrosting time is shortened, and low-temperature heat The time for the medium to flow into the combustion heat source machine 3 can be shortened, and the occurrence of dew condensation on the heat exchanger (hot water storage type heat exchanger 18 in the present embodiment) of the combustion heat source machine 3 during operation can be suppressed. By suppressing the occurrence of dew condensation, it is possible to suppress corrosion and damage to the heat exchanger of the combustion heat source machine 3. Further, since the combustion heat source machine 3 is operated during the reverse cycle defrosting, the heat medium heated by the combustion heat source machine 3 is supplied to the heating terminal 4 to continue the heating operation, and the comfort is not impaired.

The present invention is not limited to one embodiment. In the present embodiment, the hot water storage type combustion heat source machine 3 is used only for heating purposes, but the heat medium and water supply in the storage can body 21 A hot water supply heat exchanger for heat exchange or a bath heat exchanger for heat exchange between the heat medium in the storage can body 21 and the bath water is provided in the storage can body 21 to heat the hot water storage type combustion heat source machine 3. In addition to the intended use, it may be used for hot water supply or bath.

Further, in the present embodiment, the heat pump side control device 35 mainly controls the heat pump type heat source machine 2, and the combustion side control device 36 mainly controls the hot water storage type combustion heat source machine 3, but the heat pump side control device The 35 and the combustion side control device 36 may be used as one control device to control both the heat pump type heat source machine 2 and the hot water storage type combustion heat source machine 3.

1 Heating system 2 Heat pump type heat source machine 3 Hot water storage type combustion heat source machine 4 Heating terminal 5 Compressor 6 Four-way valve 7 Liquid refrigerant heat exchanger 8 Expansion valve 10 Air heat exchanger 25 Circulation circuit 29 Circulation pump 35 Heat pump side control device

Claims (1)

With a heating terminal
A circulation circuit having a circulation pump that circulates a heat medium in the heating terminal, and
The compressor having a compressor for compressing the refrigerant, a liquid refrigerant heat exchanger for heat exchange between the heat medium and the refrigerant, a switching valve, an expansion valve, and an air heat exchanger, and circulating the circulation circuit. A heat pump type heat source machine that heats the heat medium,
A combustion heat source machine that heats the heat medium that circulates in the circulation circuit,
Equipped with a control device,
In a heating system in which the combustion heat source machine is arranged on the downstream side of the heat pump type heat source machine with respect to the flow of the heat medium circulating in the circulation circuit.
When the control device determines that a predetermined defrosting start condition is satisfied when the heat medium is heated by the heat pump type heat source machine and the heating operation is performed by the heating terminal, the switching valve is set to the refrigerant. The flow direction is switched so as to be opposite to the flow direction of the refrigerant during the heating operation, and the refrigerant discharged from the compressor is supplied to the air heat exchanger to generate heat in the air heat exchanger. The reverse cycle defrosting that melts the frost is executed, the combustion heat source machine is operated, and the flow rate of the heat medium during the reverse cycle defrosting is made larger than the flow rate of the heat medium during the heating operation. A heating system characterized by the fact that it has been made.

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