JPWO2019171473A1 - Heat pump water heater - Google Patents

Abstract

The heat pump hot water supply device has a refrigerant circuit including a compressor, a condenser, a pressure reducing device, and an evaporator, and heats the heat medium circulated by the heat medium circulation device by the condenser. The heat pump water heater is a first temperature sensor that detects the discharge temperature that is the temperature of the refrigerant discharged from the compressor, and a second temperature sensor that detects the outlet temperature that is the temperature of the heat medium heated by the condenser. A control device for controlling the heat medium circulation device so that the outlet temperature becomes the target temperature. Then, the control device controls the heat medium circulation device so that the speed of the heat medium introduced into the condenser does not decrease when the temperature difference between the discharge temperature and the outlet temperature is smaller than the reference value.

Description

The present invention relates to a heat pump type hot water supply device that heats a heat medium using a refrigerant whose temperature has been raised by a heat pump using a refrigeration cycle.

Patent Document 1 discloses a technique relating to a heat pump water heater for optimizing energy consumption efficiency while controlling the hot water outlet temperature. In this technique, the rotation speed of the compressor is controlled so that the condensation temperature of the refrigerant condensed by the heat exchange in the hot water supply heat exchanger becomes the target condensation temperature. At that time, the temperature difference between the discharge temperature of the refrigerant discharged from the compressor and the condensation temperature is calculated. Then, the opening degree of the expansion valve is controlled so that the temperature difference becomes a target temperature difference that maximizes energy consumption efficiency. Further, in this technique, the rotation speed of the water supply pump is controlled so that the temperature of the hot water discharged from the hot water supply heat exchanger becomes the set hot water temperature.

Japanese Patent Laid-Open No. 2012-233626

The technique of Patent Document 1 has the following problems. That is, in the technique of Patent Document 1, the discharge temperature of the refrigerant discharged from the compressor and the hot water discharge temperature are individually controlled. The discharge temperature is low for some time after the heat pump hot water supply device starts to start. When the discharge temperature is low, in order to bring the hot water discharge temperature close to the set hot water discharge temperature, control is performed to reduce the rotational speed of the water supply pump to reduce the flow rate of hot water as the heat medium. Therefore, if the discharge temperature rises after that, the control of the water supply pump may not catch up with the change in the discharge temperature, and the hot water discharge temperature may rise excessively.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a heat pump hot water supply device capable of suppressing an excessive temperature rise of a heat medium due to heating in a condenser. To do.

The present invention is a compressor for compressing a refrigerant, a condenser for cooling the refrigerant compressed by the compressor, a decompression device for decompressing the refrigerant cooled by the condenser, and heat absorption by the refrigerant decompressed by the decompression device. The heat pump type hot water supply apparatus has a refrigerant circuit including an evaporator for performing the above, and heats the heat medium circulated by the heat medium circulation apparatus by the condenser. The heat pump water heater is a first temperature sensor that detects the discharge temperature that is the temperature of the refrigerant discharged from the compressor, and a second temperature sensor that detects the outlet temperature that is the temperature of the heat medium heated by the condenser. A control device that controls the heat medium circulation device so that the outlet temperature becomes the target temperature. The control device is configured to control the heat medium circulation device so that the speed of the heat medium introduced into the condenser does not decrease when the temperature difference between the discharge temperature and the outlet temperature is smaller than the reference value. ..

According to the heat pump hot water supply apparatus of the present invention, when the temperature difference between the discharge temperature of the refrigerant discharged from the compressor and the outlet temperature of the heat medium heated by the condenser is smaller than the reference value, the condenser The heating medium circulating device is controlled so that the speed of the heating medium introduced into the heating medium does not decrease. This makes it possible to prevent the outlet temperature from rising excessively in response to the rise in the discharge temperature.

FIG. 3 is a diagram for explaining a circuit configuration of the heat pump type hot water supply device according to the first embodiment. FIG. 3 is a control block diagram of the heat pump water heater according to the first embodiment. 3 is a flowchart showing a control routine executed in the heat pump type hot water supply device according to the first embodiment. 7 is a flowchart showing a control routine executed in the heat pump type hot water supply device according to the second embodiment. It is a figure showing an example of hardware constitutions of a control device with which a heat pump type hot water supply device of an embodiment is provided. It is a figure which shows the other example of the hardware constitutions of the control apparatus with which the heat pump type hot water supply apparatus of embodiment is equipped.

Hereinafter, embodiments will be described with reference to the drawings. Elements common to each drawing are denoted by the same reference numerals, and overlapping description will be simplified or omitted. The present disclosure may include any combination of configurations that can be combined among the configurations described in the following embodiments.

Embodiment 1.
[Configuration of Heat Pump Water Heater of First Embodiment]
FIG. 1 is a diagram for explaining the circuit configuration of the heat pump type hot water supply device according to the first embodiment. As shown in this figure, a heat pump hot water supply apparatus 100 is equipped with a compressor 1, a condenser 2, a pressure reducing valve 3 and an evaporator 4 as components constituting a heat source device utilizing a heat pump cycle. A refrigerant circuit of the heat source unit is formed by annularly connecting these components through the refrigerant pipe 12.

The compressor 1 compresses the low pressure refrigerant gas. As the refrigerant here, a single refrigerant such as HFC type R32, R410A, R404A or a natural refrigerant such as carbon dioxide or hydrocarbon is used. The condenser 2 exchanges heat between the high-temperature high-pressure refrigerant discharged from the compressor 1 and water or another liquid heat medium. The liquid heat medium may be, for example, a calcium chloride aqueous solution, an ethylene glycol aqueous solution, an alcohol, or the like.

The pressure reducing valve 3 is an example of a pressure reducing device that reduces the high-temperature and high-pressure refrigerant discharged from the compressor 1 into a low-pressure refrigerant. The reduced pressure low-pressure refrigerant is in a gas-liquid two-phase state. The evaporator 4 is a heat exchanger that exchanges heat between the low-pressure refrigerant and the atmosphere. In the evaporator 4, the low pressure refrigerant evaporates by absorbing the heat of the atmosphere. The blower (not shown) blows air to the evaporator 4, so that heat exchange in the evaporator 4 can be promoted. The low-pressure refrigerant gas evaporated in the evaporator 4 is sucked into the compressor 1. A first temperature sensor 6 for detecting the temperature of the refrigerant discharged from the compressor 1 is installed in the refrigerant pipe 12 on the discharge side of the compressor 1. In the following description, the temperature of the refrigerant detected by the first temperature sensor 6 is referred to as "discharge temperature Td".

On the other hand, the circulation circuit for hot water supply includes the condenser 2 and the circulation pump 5 described above. The outlet side of the heat medium in the condenser 2 is connected to the upper part of a hot water storage tank (not shown) by the first flow path 9. The heat medium inlet side of the condenser 2 is connected to the lower part of the hot water storage tank by the second flow path 10. The circulation pump 5 is an example of a heat medium circulation device that circulates the heat medium to the condenser 2. The circulation pump 5 is installed in the middle of the second flow path 10. A second temperature sensor 7 for detecting the temperature of the heat medium on the outlet side of the condenser 2 is installed in the middle of the first flow path 9. In the following description, the temperature of the refrigerant detected by the second temperature sensor 7 will be referred to as “outlet temperature Two”.

Water before heating and hot water after heating are stored in the hot water storage tank. In the hot water storage tank, due to the difference in the specific gravity of water depending on the temperature, a temperature stratification in which the upper side is high temperature and the lower side is low temperature is formed. A hot water supply pipe (not shown) for supplying hot water to terminals such as a hot water tap, a shower and a bathtub is connected to the upper part of the hot water storage tank. A water supply pipe (not shown) for supplying water from a water source such as a tap is connected to the lower portion of the hot water storage tank. When hot water is supplied from the hot water storage tank, the hot water in the upper portion of the hot water storage tank is delivered to the hot water supply pipe by the water pressure acting from the water supply pipe into the hot water storage tank. The same amount of water as the hot water flowing out to the hot water supply pipe flows into the hot water storage tank from the water supply pipe, so that the hot water storage tank is kept full.

The heat pump hot water supply device 100 can perform a heat storage operation of storing hot water heated by a heat source device in a hot water storage tank, for example. At the time of heat storage operation, it becomes as follows. The compressor 1, the blower, and the circulation pump 5 are operated. Water flowing out from the lower part of the hot water storage tank flows into the inside of the condenser 2 through the second flow path 10. This water is heated by the high-temperature and high-pressure refrigerant in the condenser 2 to become hot water. The hot water flowing out of the condenser 2 flows into the upper part of the hot water storage tank through the first flow path 9.

The heat pump type hot water supply device of the present invention is not limited to a part of the hot water supply device such as the heat pump type hot water supply device 100, but may be used for heating a liquid heat medium in a hot water heating system, for example. .. That is, the liquid heat medium heated by the heat pump type hot water supply device of the present invention, for example, a floor heating panel installed under the floor, a radiator or panel heater installed on the indoor wall surface, or to a heating appliance such as a fan convector. May be supplied.

FIG. 2 is a control block diagram of heat pump water heater 100 of the first embodiment. Hereinafter, the configuration of the control system of heat pump hot water supply apparatus 100 according to Embodiment 1 will be described with reference to FIG. 2 as well.

Heat pump hot water supply apparatus 100 of the present embodiment includes control device 8. The first temperature sensor 6 and the second temperature sensor 7 are electrically connected to the input side of the control device 8. The compressor 1, the pressure reducing valve 3, and the circulation pump 5 are electrically connected to the output side of the control device 8. The controller 8 controls the operation of the compressor 1. The operating speed of the compressor 1 is variable. The control device 8 can change the operating speed of the compressor 1 by making the operating speed (Hz) of the compressor 1 variable by the inverter control. The higher the operating speed of the compressor 1, the higher the operating speed of the compressor 1. The higher the operating speed of the compressor 1, the higher the circulation speed of the refrigerant, and the higher the amount of heat that the refrigerant supplies to the condenser 2 per unit time.

The control device 8 controls the operation of the pressure reducing valve 3. The control device 8 adjusts the pressure of the refrigerant introduced into the evaporator 4 by controlling the opening degree of the pressure reducing valve 3.

Further, the control device 8 controls the operation of the circulation pump 5. The control device 8 controls the output of the circulation pump 5 so that the outlet temperature Two detected by the second temperature sensor 7 becomes the target temperature Tt at the outlet temperature of the condenser 2. In the following description, this control is referred to as "outlet temperature control". The control logic of the outlet temperature control is not limited. For example, when the outlet temperature Two is lower than the target temperature Tt, the control device 8 decreases the output of the circulation pump 5 so that the speed of the heat medium circulated by the circulation pump 5 decreases. Control. On the other hand, when the outlet temperature Two is higher than the target temperature Tt, the control device 8 controls to increase the output of the circulation pump 5 so that the speed of the heat medium circulated by the circulation pump 5 increases. At this time, the control device 8 may control the output of the circulation pump 5 such that the larger the deviation between the outlet temperature Two and the target temperature Tt, the larger the change amount of the output. Further, the control device 8 may control the output of the circulation pump 5 such that the larger the deviation between the outlet temperature Two and the target temperature Tt, the larger the amount of change in the control constant used for the outlet temperature control.

[Operation of Heat Pump Water Heater of First Embodiment]
Next, the operation of heat pump hot water supply apparatus 100 of the first embodiment will be described. When the heat medium is heated by the heat source device as in the heat storage operation described above, the control device 8 controls the compressor 1 and the pressure reducing valve 3 to drive the heat source device. Further, the control device 8 executes the outlet temperature control, and drives the output of the circulation pump 5 so that the outlet temperature Two becomes the target temperature Tt. According to such an operation, the heat medium can be heated to the target temperature.

Here, the inventor of the present application has recognized the following problems regarding the above outlet temperature control. This is because the discharge temperature Td of the refrigerant discharged from the compressor 1 may not immediately rise when the heat pump hot water supply device 100 starts to start. If the outlet temperature control is executed so that the outlet temperature Two becomes the target temperature Tt in such a period, the circulation speed of the heat medium by the circulation pump 5 may become too low. As a result, when the discharge temperature Td of the refrigerant discharged from the compressor 1 thereafter rises, the operation of the circulation pump 5 due to the outlet temperature control cannot catch up, and the outlet temperature Two of the heat medium rises excessively. There is a risk.

In heat pump hot water supply apparatus 100 of the present embodiment, the above problems are solved by the following configurations. That is, for example, immediately after the heat pump hot water supply apparatus 100 is activated, the temperature difference between the discharge temperature Td and the outlet temperature Two tends to be small during the period when the discharge temperature Td is relatively low. Therefore, the temperature difference can be used as an index for determining whether the operation of the heat source device is stable.

Therefore, when the temperature difference between the discharge temperature Td and the outlet temperature Two is smaller than the reference value A, the control device 8 controls the circulation pump 5 so that the speed of the heat medium flowing into the condenser 2 does not decrease. More specifically, when the temperature difference is smaller than the reference value A, the control device 8 sets the speed of the heat medium flowing into the condenser 2 to be higher than when the temperature difference is larger than the reference value A. The circulation pump 5 is controlled. The reference value A is a threshold value of a temperature difference for determining that the discharge temperature Td has risen and the operation of the heat source device is stable. As such a reference value A, for example, a value specified in advance by an experiment or the like can be used.

When the velocity of the heat medium flowing into the condenser 2 is increased, the flow rate of the heat medium passing through the condenser 2 is increased. Therefore, even if the discharge temperature Td subsequently rises and the amount of heat on the refrigerant side of the condenser 2 sharply increases, it is possible to prevent the temperature of the heat medium that has passed through the condenser 2 from rapidly rising. .. This makes it possible to prevent the discharge temperature Td from excessively rising in the heat pump water heater 100.

[Specific Processing of Heat Pump Water Heater of First Embodiment]
Next, a specific process of control executed in the heat pump hot water supply apparatus according to the first embodiment will be described with reference to the flowchart. FIG. 3 is a flowchart showing a control routine executed in the heat pump hot water supply apparatus according to the first embodiment. This flowchart is repeatedly executed by control device 8 while the heat pump hot water supply device 100 is operating.

In the routine shown in FIG. 3, first, the outlet temperature control is executed (step S2). Here, specifically, the output of the circulation pump 5 is controlled so that the outlet temperature Two detected by the second temperature sensor 7 becomes the target temperature Tt. Next, it is determined whether the temperature difference between the discharge temperature Td detected by the first temperature sensor 6 and the outlet temperature Two detected by the second temperature sensor 7 is smaller than the reference value A (step S4). ..

If the determination is not established in step S4, it is possible to determine that the outlet temperature Two can be controlled to the target temperature Tt by the outlet temperature control because the heat source machine is operating stably. In this case, this routine is ended, and the outlet temperature control of step S2 is executed in the next routine.

On the other hand, if it is determined in step S4 that the determination is successful, it is determined that the refrigerant discharged from the compressor 1 has not been sufficiently heated because the heat source machine is not operating stably. You can In this case, it can be determined that the heat medium may be excessively heated due to the subsequent temperature rise of the discharged refrigerant. In this case, the process proceeds to the next step, and the circulation speed of the heat medium is increased (step S6). Here, specifically, the circulation speed of the heat medium is increased by increasing the output of the circulation pump 5.

As described above, according to the heat pump hot water supply apparatus of the first embodiment described above, the circulation speed of the heat medium is controlled to be high in a situation where the discharged refrigerant is not sufficiently heated. This makes it possible to prevent the heat medium from excessively rising even if the temperature of the discharged refrigerant sharply rises thereafter.

Embodiment 2.
[Characteristics of Heat Pump Water Heater of Second Embodiment]
Next, a second embodiment of the present invention will be described. The heat pump hot water supply apparatus according to the second embodiment can be realized by using the hardware configuration shown in FIG. 1 and causing control device 8 to execute the flowchart of FIG. 4 described later.

In heat pump hot water supply apparatus 100 of the second embodiment, changing the operating value of circulation pump 5 is prohibited as means for controlling circulation pump 5 so that the speed of the heat medium introduced into condenser 2 does not decrease. By prohibiting the change of the operation value of the circulation pump 5, the circulation speed of the heat medium does not become lower than the current one. This makes it possible to prevent the heat medium from excessively rising even if the temperature of the discharged refrigerant sharply rises thereafter.

[Specific Processing of Heat Pump Water Heater of Second Embodiment]
Next, a specific process of control executed in the heat pump hot water supply device of the second embodiment will be described with reference to the flowchart. FIG. 4 is a flowchart showing a control routine executed in the heat pump hot water supply apparatus according to the second embodiment. This flowchart is repeatedly executed by control device 8 while the heat pump hot water supply device 100 is operating.

In the routine shown in FIG. 4, first, the outlet temperature control is executed (step S12). Here, specifically, the same processing as step S2 of the routine shown in FIG. 3 is executed. Next, it is determined whether the temperature difference between the discharge temperature Td detected by the first temperature sensor 6 and the outlet temperature Two detected by the second temperature sensor 7 is smaller than the reference value A (step S14). .. Here, the same processing as step S4 of the routine shown in FIG. 3 is executed.

When the determination is not established in step S14, it is possible to determine that the outlet temperature Two can be controlled to the target temperature Tt by the outlet temperature control because the heat source machine is operating stably. In this case, this routine is ended, and the outlet temperature control of step S12 is executed in the next routine.

On the other hand, if the determination is successful in step S14, it is determined that the refrigerant discharged from the compressor 1 has not been sufficiently heated because the heat source machine is not operating stably. You can In this case, it is determined that the heat medium may excessively rise due to the subsequent temperature rise of the discharged refrigerant, and the process proceeds to the next step. In the next step, changing the operating value of the circulation pump 5 is prohibited (step S16). Thereby, the circulation speed of the heat medium is maintained constant.

As described above, according to the heat pump hot water supply apparatus of the second embodiment described above, the circulation speed of the heat medium is maintained constant so as not to decrease in a situation where the discharged refrigerant has not been sufficiently heated. This makes it possible to prevent the heat medium from excessively rising even if the temperature of the discharged refrigerant sharply rises thereafter.

By the way, control device 8 included in heat pump hot water supply device 100 of the first or second embodiment may be configured as follows. FIG. 5 is a diagram illustrating an example of a hardware configuration of the control device 8 included in the heat pump hot water supply device 100 according to the embodiment. Each function of the control device 8 is realized by a processing circuit. In the example shown in FIG. 5, the processing circuit of the control device 8 includes at least one processor 81 and at least one memory 82.

When the processing circuit includes at least one processor 81 and at least one memory 82, each function of the control device 8 is realized by software, firmware, or a combination of software and firmware. At least one of software and firmware is described as a program. At least one of software and firmware is stored in at least one memory 82. At least one processor 81 realizes each function of the control device 8 by reading and executing a program stored in at least one memory 82. At least one processor 81 is also called a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, and a DSP (Digital Signal Processor). For example, the at least one memory 82 may be a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read-Only Memory), an EEPROM (Electrically Programmable Memory), or an EEPROM (Electrically Programmable Era). Further, it is a volatile semiconductor memory, a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD (Digital Versatile Disc), or the like.

FIG. 6 is a diagram showing another example of the hardware configuration of the control device 8 included in the heat pump hot water supply device 100 according to the embodiment. In the example shown in FIG. 6, the processing circuit of the control device 8 includes at least one dedicated hardware 83.

When the processing circuit includes at least one dedicated hardware 83, the processing circuit may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field). -Programmable Gate Array), or a combination thereof. The function of each unit of the control device 8 may be realized by a processing circuit. Further, the functions of the respective units of the control device 8 may be collectively realized by the processing circuit.

Further, each function of the control device 8 may be partially realized by the dedicated hardware 83 and the other part may be realized by software or firmware. In this way, the processing circuit realizes each function of the control device 8 by the hardware 83, software, firmware, or a combination thereof.

1 compressor, 2 condenser, 3 pressure reducing valve, 4 evaporator, 5 circulation pump (heat medium circulation device), 6 first temperature sensor, 7 second temperature sensor, 8 control device, 9 first flow path, 10 second Flow path, 12 Refrigerant piping, 81 Processor 82 Memory 83 Hardware 100 Heat pump water heater

Claims (3)

A compressor for compressing a refrigerant, a condenser for cooling the refrigerant compressed by the compressor, a decompression device for decompressing the refrigerant cooled by the condenser, and heat absorption to the refrigerant decompressed by the decompression device. In the heat pump type hot water supply device, which has a refrigerant circuit including an evaporator to perform, and heats the heat medium circulated by the heat medium circulation device by the condenser,
A first temperature sensor for detecting a discharge temperature which is the temperature of the refrigerant discharged from the compressor,
A second temperature sensor for detecting the outlet temperature which is the temperature of the heat medium heated by the condenser,
A control device for controlling the heat medium circulation device so that the outlet temperature becomes a target temperature,
When the temperature difference between the discharge temperature and the outlet temperature is smaller than a reference value, the control device controls the heat medium circulation device so that the speed of the heat medium introduced into the condenser does not decrease. Heat pump type hot water supply device. The control device, when the temperature difference is smaller than the reference value, as compared to when the temperature difference is larger than the reference value, so that the speed of the heat medium introduced into the condenser is high, The heat pump water heater according to claim 1, which is configured to control the heat medium circulation device. The control device is configured to perform control so as to prohibit a change in an operating value of the heat medium circulation device when the temperature difference is smaller than the reference value. The heat pump water heater described.

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