EP3258185B1

EP3258185B1 - Heat supply system

Info

Publication number: EP3258185B1
Application number: EP15881947.4A
Authority: EP
Inventors: Satoshi Akagi; Yasunari Matsumura; Naoki SHIBAZAKI
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2015-02-12
Filing date: 2015-02-12
Publication date: 2020-07-29
Anticipated expiration: 2035-02-12
Also published as: EP3258185A4; JP6399113B2; JPWO2016129072A1; WO2016129072A1; EP3258185A1

Description

[Technical Field]

The present invention relates to a heat supply system.

[Background Art]

PTL 1 listed below discloses a heat pump water heater that includes a water heater circuit in which a refrigerant-water heat exchanger for a heat pump and a heating device including an electric heater are connected sequentially. This heat pump water heater includes a first temperature detector that is provided downstream of the refrigerant-water heat exchanger, and a second temperature detector that is provided downstream of the heating device. In the heat pump water heater, in a case where the set temperature of hot water is relatively low, the electric heater of the heating device is brought into a non-energized state, and the rotation speed of a circulation pump is controlled using a signal of the first temperature detector such that the temperature of hot water at the outlet of the refrigerant-water heat exchanger becomes constant. In the heat pump water heater, in a case where the set temperature of hot water is high, the electric heater of the heating device is energized, and the rotation speed of the circulation pump is controlled using a signal of the second temperature detector such that the temperature of hot water at the outlet of the heating device becomes constant.

[Citation List]

[Patent Literature]

[PTL 1] Japanese Patent Application Laid-open No. H8-14657
JP S60 164157 A discloses a heat supply system according to the preamble of claim 1 comprising a first heating device and a second heating device for providing hot water which are arranged in a water circulating circuit. The temperature of the hot water is controlled to be constant by a control mechanism of circulating water amount.
Further, JP H5 256520 describes a hot water supply system which uses an auxiliary heat source which is operated during a period in which the output of a heat pump during starting the operation is stabilized. Thereby, a ratio of a quantity of utilizable hot water to the capacity of a hot water storage tank can be maximized.
DE 3322612 A1 refers to a hot water supply system comprising a second heat source which is controlled depending on the temperature of the hot water.

[Summary of Invention]

[Technical Problem]

In cases where the electric heater of the heating device is brought into a non-energized state in the conventional heat pump water heater described above, there is a possibility that heat of hot water coming out of the refrigerant-water heat exchanger is removed while the hot water is passing through the heating device not generating heat, resulting in the temperature of the hot water being reduced. As a consequence, the temperature of supplied hot water may undershoot. In addition, in the case where the length of a flow path between the refrigerant-water heat exchanger and the heating device is large, the temperature of hot water may be reduced while the hot water coming out of the refrigerant-water heat exchanger is flowing to the heating device. As a result, the temperature of the supplied hot water may undershoot. Further, in the case where the electric heater of the heating device is turned ON from its OFF state in the heat pump water heater, the temperature of the supplied hot water may overshoot.
The present invention has been made in order to solve the above problems. An object of the present invention is to prevent undershooting and overshooting of the temperature of a heating medium in a heat supply system that includes a first heating device and a second heating device.

[Solution to Problem]

A heat supply system of the invention is defined by the features of claim 1. Preferred embodiments are represented in the dependent claims.
A heat supply system of the invention includes: a pump configured to pump a heating medium; a first heating device configured to heat the heating medium; a second heating device configured to heat the heating medium downstream of the first heating device; and a controller configured to reduce a heating power of the first heating device concurrently with or before activation of the second heating device, in a case where the second heating device is activated in a state in which the first heating device is operated without operating the second heating device.

[Advantageous Effects of Invention]

According to the present invention, it becomes possible to prevent the undershooting and the overshooting of the temperature of the heating medium in the heat supply system that includes the first heating device and the second heating device.

[Brief Description of Drawings]

Fig. 1 is a configuration diagram showing a heat supply system of Embodiment 1 of the present invention.
Fig. 2 is a block diagram showing a flow of a signal of the heat supply system of Embodiment 1.
Fig. 3 is a hardware configuration diagram of the heat supply system of Embodiment 1.
Fig. 4 is a flowchart of a routine executed by a controller of the heat supply system not covered by the invention.
Fig. 5 is a flowchart showing a second example of a method for determining whether a temperature condition of a heating medium is stabilized.
Fig. 6 is a flowchart showing a third example of the method for determining whether the temperature condition of the heating medium is stabilized.
Fig. 7 is a graph showing an example of a change in a detected temperature of each of a main thermistor and an auxiliary thermistor after an activation of a main heat source.
Fig. 8 is a graph showing an example of a change in the detected temperature of each of the main thermistor and the auxiliary thermistor after the activation of the main heat source.
Fig. 9 is a graph showing an example of the change in the detected temperature of each of the main thermistor and the auxiliary thermistor after the activation of the main heat source.
Fig. 10 is a flowchart of a routine executed by a controller of a heat supply system according to the invention.
Fig. 11 is a graph showing an example of a change in temperatures in a vicinity of an upstream side and a downstream side of an auxiliary heat source in a case where the auxiliary heat source is activated in a state in which a main heat source is operated and the auxiliary heat source is not operated.
Fig. 12 is a graph showing an example of a change in temperatures in the vicinity of the downstream side and the upstream side of the auxiliary heat source in the case where the auxiliary heat source is activated in the state in which the main heat source is operated and the auxiliary heat source is not operated.
Fig. 13 is a flowchart of a routine executed by a controller of a heat supply system of Embodiment 3.
Fig. 14 is a graph showing an example of a change in temperatures in a vicinity of a downstream side and an upstream side of an auxiliary heat source in a case where the auxiliary heat source is activated in a state in which a main heat source is operated and the auxiliary heat source is not operated.
Fig. 15 is a graph showing an example of a change in the temperatures in the vicinity of the downstream side and the upstream side of the auxiliary heat source in the case where the auxiliary heat source is activated in the state in which the main heat source is operated and the auxiliary heat source is not operated.

[Description of Embodiments]

Hereinbelow, embodiments of the present invention will be described with reference to the drawings. Note that common elements in the drawings are denoted by the same reference numerals, and the duplicate description thereof will be omitted.

Embodiment 1

Fig. 1 is a configuration diagram showing a heat supply system of Embodiment 1 of the present invention. A heat supply system 1 of the present embodiment shown in Fig. 1 is a hot water supply indoor-heating system. The heat supply system 1 includes a first unit 2, a second unit 3, and a controller 100. In the present embodiment, the first unit 2 is placed outdoors, and the second unit 3 is placed indoors. The second unit 3 may also be placed outdoors. The first unit 2 and the second unit 3 are connected via heating medium pipes 4 and 5.
The first unit 2 includes a first casing in which a main heat source 6 is housed. The main heat source 6 is an example of a first heating device that heats a liquid heating medium. As the heating medium, it is possible to use, e.g., water, brine, and antifreeze solution. The main heat source 6 in the present embodiment is a heat pump heating device. The main heat source 6 includes a refrigerant circuit. The refrigerant circuit includes a compressor 7, a high-temperature side heat exchanger 8, a decompression device 9, and a low-temperature side heat exchanger 10. The main heat source 6 heats the heating medium by performing an operation of a heat pump cycle (refrigeration cycle) with the refrigerant circuit. The high-temperature side heat exchanger 8 heats the heating medium by exchanging heat between the refrigerant compressed by the compressor 7 and the heating medium. The decompression device 9 reduces the pressure of the refrigerant having passed through the high-temperature side heat exchanger 8. The decompression device 9 is constituted by, e.g., an expansion valve. The low-temperature side heat exchanger 10 is an evaporator that evaporates the refrigerant having passed through the decompression device 9. In the present embodiment, the low-temperature side heat exchanger 10 exchanges heat between outdoor air and the refrigerant. The main heat source 6 includes a blower 11 that blows outside air into the low-temperature side heat exchanger 10. The low-temperature side heat exchanger 10 may exchange heat between the heat source other than the outside air (e.g., groundwater, wastewater, and solar heated water) and the refrigerant. The refrigerant is preferably CO₂.
The compressor 7, the decompression device 9, and the blower 11 are connected to the controller 100. The controller 100 is capable of controlling the heating power of the main heat source 6. The heating power denotes an amount of heat per unit time that the heating medium receives. The controller 100 is capable of controlling the heating power of the main heat source 6 by, e.g., changing the driving frequency of the compressor 7 using inverter control. The controller 100 may control the heating power of the main heat source 6 by changing the opening of the decompression device 9.
The second unit 3 includes a second casing in which an auxiliary heat source 12 is housed. The auxiliary heat source 12 is an example of a second heating device that heats the heating medium downstream of the high-temperature side heat exchanger 8 of the main heat source 6. As the auxiliary heat source 12, it is possible to use, e.g., an electric heater or a fuel heater. In the case of the fuel heater, the fuel may be any fuel such as gas, kerosene, heavy oil, and coal. The auxiliary heat source 12 is operated when the heating power of the main heat source 6 is insufficient, and compensates for the insufficiency of the heating power. An example of the case where the heating power of the main heat source 6 becomes insufficient includes the case where the temperature of the medium (outdoor air in the present embodiment) used in the heat exchange with the refrigerant in the low-temperature side heat exchanger 10 of the main heat source 6 is low.
In the second unit 3, a hot water tank 13, a hot water supply heat exchanger 14, a heating medium pump 15, a water pump 16, and a switching valve 17 are further housed. The auxiliary heat source 12, the heating medium pump 15, the water pump 16, and the switching valve 17 are connected to the controller 100. The hot water supply heat exchanger 14 heats water by exchanging heat between the heating medium and water. The outlet of the heating medium of the hot water supply heat exchanger 14 is connected to the inlet of the heating medium pump 15. The outlet of the heating medium pump 15 is connected to the inlet of the heating medium of the high-temperature side heat exchanger 8 in the first unit 2 via the heating medium pipe 4. The outlet of the heating medium of the high-temperature side heat exchanger 8 is connected to the inlet of the auxiliary heat source 12 in the second unit 3 via the heating medium pipe 5.
The switching valve 17 has an A port, a B port, and a C port. The switching valve 17 is capable of switching between a state in which the A port is caused to communicate with the B port and the C port is closed and a state in which the A port is caused to communicate with the C port and the B port is closed. The switching valve 17 may also be capable of switching to a state in which the heating medium flowing in from the A port is distributed to the B port and the C port. The outlet of the auxiliary heat source 12 is connected to the A port of the switching valve 17. The B port of the switching valve 17 is connected to the inlet of the heating medium of the hot water supply heat exchanger 14.
Water is stored in the hot water tank 13. In the hot water tank 13, it is possible to form temperature stratification in which the upper side has high temperature and the lower side has low temperature due to a difference in the density of water caused by a difference in temperature. Clean water supplied from a water source 40 such as water works passes through a water supply pipe 18 and flows into the lower portion of the hot water tank 13. In a heat accumulating circuit that accumulates heat in the hot water tank 13, the lower portion of the hot water tank 13 is connected to the inlet of water of the hot water supply heat exchanger 14, and the outlet of water of the hot water supply heat exchanger 14 is connected to the upper portion of the hot water tank 13. The water pump 16 circulates water to the heat accumulating circuit. A hot water supply pipe 19 is connected to the upper portion of the hot water tank 13. The downstream side of the hot water supply pipe 19 is connected to a hot water faucet 20 outside the second unit 3. When the hot water faucet 20 is opened, hot water stored in the hot water tank 13 is supplied to the hot water faucet 20 through the hot water supply pipe 19. A mixing valve (depiction thereof is omitted) for mixing hot water and cold water to adjust temperature may be disposed in the middle of the hot water supply pipe 19.
An indoor-heating appliance 21 warms indoor air by using heat of the heating medium supplied from the second unit 3. The C port of the switching valve 17 is connected to the inlet of the heating medium of the indoor-heating appliance 21 via a heating medium pipe 22. One end of a heating medium pipe 23 is connected to the outlet of the heating medium of the indoor-heating appliance 21. The other end of the heating medium pipe 23 is connected to a flow path between the outlet of the heating medium of the hot water supply heat exchanger 14 and the inlet of the heating medium pump 15. As the indoor-heating appliance 21, it is possible to use, e.g., a floor heating panel, a radiator, a panel heater, and a fan convector. A plurality of the indoor-heating appliances 21 may also be connected between the heating medium pipe 22 and the heating medium pipe 23. In this case, a method for connecting the plurality of the indoor-heating appliances 21 may be any of series connection, parallel connection, and a combination of the series connection and the parallel connection.
Each of the hot water tank 13, the hot water supply heat exchanger 14, the hot water faucet 20, and the indoor-heating appliance 21 is an example of a heat use terminal as a terminal that uses heat supplied by the heat supply system 1. The heat use terminal may also be a terminal other than the heat use terminals mentioned above. The heat use terminal may also be a terminal that uses heat by directly discharging a heated heating medium. The number of the heat use terminals does not need to be plural as in the present embodiment, and the number thereof may also be one.
In each of the heating medium pump 15 and the water pump 16, output or rotation speed thereof is preferably variable. As each of the heating medium pump 15 and the water pump 16, for example, the pump that includes a pulse width modulation control (PWM control) type DC motor of which the output or rotation speed can be changed with a speed command voltage from the controller 100 can be preferably used.
In the heating medium pipe 5 downstream of the main heat source 6 and upstream of the auxiliary heat source 12, an auxiliary thermistor 24 is disposed. The auxiliary thermistor 24 is an example of a first temperature sensor that detects the temperature of the heating medium downstream of the first heating device (the main heat source 6) and upstream of the second heating device (the auxiliary heat source 12). The auxiliary thermistor 24 is disposed in the first unit 2. The length of a flow path from the main heat source 6 to the auxiliary thermistor 24 is preferably shorter than the length of a flow path from the auxiliary thermistor 24 to the auxiliary heat source 12. The temperature of the heating medium downstream of the main heat source 6 and upstream of the auxiliary heat source 12 is hereinafter referred to as an "outlet temperature of the main heat source 6". The auxiliary thermistor 24 is capable of detecting the outlet temperature of the main heat source 6.
In a flow path of the heating medium downstream of the auxiliary heat source 12 and upstream of the heat use terminal, a main thermistor 25 is disposed. The main thermistor 25 is an example of a second temperature sensor that detects the temperature of the heating medium downstream of the second heating device (the auxiliary heat source 12). The main thermistor 25 detects the temperature of the heating medium downstream of the auxiliary heat source 12 and upstream of the switching valve 17. The temperature of the heating medium downstream of the auxiliary heat source 12 is hereinafter referred to as a "heating medium supply temperature". The main thermistor 25 is capable of detecting the heating medium supply temperature.
In a flow path of the heating medium downstream of the heat use terminal and upstream of the main heat source 6, a low-temperature thermistor 26 is disposed. The low-temperature thermistor 26 is an example of a third temperature sensor that detects the temperature of the heating medium upstream of the first heating device (the main heat source 6). The low-temperature thermistor 26 is disposed upstream of the heating medium pump 15. The low-temperature thermistor 26 may also be disposed in the heating medium pipe 4 downstream of the heating medium pump 15. A flow rate sensor 27 detects the flow rate of the heating medium that flows in the main heat source 6 and the auxiliary heat source 12. In a configuration shown in the drawing, the flow rate sensor 27 is disposed in the heating medium pipe 4 downstream of the heating medium pump 15. A room temperature thermistor 28 is an example of a room temperature sensor that detects the room temperature of a room in which the indoor-heating appliance 21 is disposed. A plurality of hot water temperature sensors 30a, 30b, and 30c are mounted to the surface of the hot water tank 13 at intervals in a vertical direction. The controller 100 is capable of calculating, for example, the amount of hot water and the amount of stored heat in the hot water tank 13 by detecting a temperature distribution in the vertical direction in the hot water tank 13 using the hot water temperature sensors 30a, 30b, and 30c. In the configuration shown in the drawing, the number of the hot water temperature sensors is three. However, the number of the hot water temperature sensors is not limited to three.
The controller 100 controls the operation of each of the main heat source 6, the auxiliary heat source 12, the heating medium pump 15, the water pump 16, and the switching valve 17. In the case where the heating power of the main heat source 6 is insufficient for the request of the heat use terminal, the controller 100 activates the auxiliary heat source 12.
The heat supply system 1 is capable of switching between a heat accumulating operation and an indoor-heating operation. In the indoor-heating operation, the switching valve 17 is controlled such that the heating medium is circulated to the indoor-heating appliance 21. In the heat accumulating operation, the switching valve 17 is controlled such that the heating medium is circulated to the hot water supply heat exchanger 14. In the heat accumulating operation, the water pump 16 is driven, and water of the hot water tank 13 is circulated to the hot water supply heat exchanger 14. In the hot water supply heat exchanger 14, water is heated with the heat of the heating medium. Hot water that comes out of the hot water supply heat exchanger 14 returns to the hot water tank 13, whereby the heat of the hot water is accumulated in the hot water tank 13.
In the present embodiment, the first unit 2 in which the main heat source 6 is housed and the second unit 3 in which the auxiliary heat source 12 and the hot water tank 13 are housed are configured to be separated from each other. By disposing the auxiliary thermistor 24 in the first unit 2, it is possible to use the auxiliary thermistor 24 for protection control of the main heat source 6. The main thermistor 25 is capable of detecting the temperature of the heating medium having passed through the main heat source 6 and the auxiliary heat source 12, i.e., the heating medium supply temperature. By disposing the main thermistor 25 in the second unit 3, it is possible to detect the heating medium supply temperature at a position close to the heat use terminal. That is, it is possible to accurately detect the temperature of the heating medium that is supplied to the heat use terminal. As a result, it is possible to control the temperature of the heating medium supplied to the heat use terminal with high accuracy. In the case where the second unit 3 is disposed indoors, it is possible to increase the ambient temperature of the second unit 3 as compared with the case where the second unit 3 is disposed outdoors, and hence it is possible to improve thermal insulation performance of the hot water tank 13. In the case where the second unit 3 is disposed indoors, it is possible to reduce the distance between the auxiliary heat source 12 and the heat use terminal, and hence it is possible to reduce loss of heat supplied to the heating medium from the auxiliary heat source 12. In the present embodiment, the heating medium pump 15, the water pump 16, the auxiliary heat source 12, the hot water tank 13, and the hot water supply heat exchanger 14 are housed in the second unit 3. However, at least one of them may also be housed in the first unit 2.
The configuration of the heat supply system of the present invention is not limited to the configuration described above, and the heat supply system may be configured in, e.g., the following manner. The first unit 2 and the second unit 3 may be integrated with each other instead of being separated from each other. Hot water heated in the hot water supply heat exchanger 14 may be supplied to the hot water faucet 20 without intervention of the hot water tank 13. The heating medium having passed through the first heating device and the second heating device may be circulated directly to the indoor-heating appliance 21. Water may be used as the heating medium heated by the first heating device and the second heating device, and hot water having passed through the first heating device and the second heating device may be supplied directly to the hot water tank 13 or the hot water faucet 20, for example. The high-temperature side heat exchanger 8 may be divided into a portion for hot water supply and a portion for indoor-heating.
Fig. 2 is a block diagram showing the flow of a signal of the heat supply system 1 of Embodiment 1. As shown in Fig. 2, detection information is inputted to the controller 100 from the hot water temperature sensors 30a, 30b, and 30c, the main thermistor 25, the auxiliary thermistor 24, the low-temperature thermistor 26, the room temperature thermistor 28, and the flow rate sensor 27. The controller 100 includes a main heat source operation determination section 101, a main heat source power control section 102, an auxiliary heat source operation determination section 103, a heating medium pump control section 104, and a water pump control section 105. The controller 100 and a remote control 200 are connected to each other so as to be capable of interactive data communication. The communication between the controller 100 and the remote control 200 may be wired communication or wireless communication. The remote control 200 includes an operation section such as a switch operated by a user, and a display section that displays information on the state of the heat supply system 1 or the like. The controller 100 receives information from the hot water temperature sensors 30a, 30b, and 30c, the main thermistor 25, the auxiliary thermistor 24, the low-temperature thermistor 26, the room temperature thermistor 28, the flow rate sensor 27, and the remote control 200, and controls the operations of the main heat source 6, the auxiliary heat source 12, the heating medium pump 15, the water pump 16, and the switching valve 17 based on the information.
Fig. 3 is a hardware configuration diagram of the controller 100 of the heat supply system 1 of Embodiment 1. The controller 100 includes a processor 1000 and a memory 1001. The function of the controller 100 is achieved by execution of a program stored in the memory 1001 by the processor 1000. A plurality of the processors and a plurality of the memories may achieve the function of the controller 100 in cooperation with each other.
A user can perform, e.g., the following operations by operating the remote control 200.

(1) The user can set target values of the temperature of hot water accumulated in the hot water tank 13 and the temperature of hot water supplied to the hot water faucet 20.
(2) The user can set a determination criterion for automation of the operation of the heat supply system 1. For example, the user can set the criterion of the amount of hot water or the amount of stored heat in the hot water tank 13 when the heat accumulating operation is automatically started, and the criterion of the amount of hot water or the amount of stored heat in the hot water tank 13 when the heat accumulating operation is automatically ended.
(3) The user can directly start and end the heat accumulating operation or the indoor-heating operation.
(4) The user can set a time period in which the heat accumulating operation or the indoor-heating operation is performed.
(5) The user can set a target value of the heating medium supply temperature in the indoor-heating operation.
(6) The user can set a target value of room temperature in the indoor-heating operation.

The controller 100 determines whether the heat accumulating operation or the indoor-heating operation is necessary according to determination criteria set by the user. The controller 100 may learn the daily use amount of hot water and may predict the use amount of hot water based on the learning result. The controller 100 may control the heat accumulating operation such that a hot water shortage in the hot water tank 13 does not occur in accordance with the predicted use amount of hot water. The controller 100 may automatically execute the indoor-heating operation based on the target value of the room temperature set by the user and the detected temperature of the room temperature thermistor 28.
The main heat source operation determination section 101 determines whether the operation of the main heat source 6 is necessary. The main heat source power control section 102 controls the heating power of the main heat source 6 by specifying, e.g., the frequency of the compressor 7. The heating medium pump control section 104 controls a circulation flow rate of the heating medium by specifying, e.g., the output or rotation speed of the heating medium pump 15. The controller 100 is capable of performing feedback control such that the temperature of the heating medium detected by the main thermistor 25 or the auxiliary thermistor 24 converges to a target value. In the feedback control, the controller 100 may control the heating power of the main heat source 6 such that the heating power thereof is substantially constant by making the frequency of the compressor 7 substantially constant, and may adjust the circulation flow rate of the heating medium.
The water pump control section 105 controls the flow rate of water that passes through the hot water supply heat exchanger 14 by specifying, e.g., the output or rotation speed of the water pump 16. The water pump control section 105 controls the water pump 16 such that the temperature of hot water accumulated in the hot water tank 13 has the target value. The heating medium pump 15 during the heat accumulating operation is usually operated such that the heating medium flow rate that prioritizes energy saving is provided. The heating medium flow rate that prioritizes energy saving is a flow rate that is substantially equal to the water flow rate by the water pump 16. The controller 100 may control the heating medium pump 15 and the water pump 16 such that the heating medium flow rate and the water flow rate become substantially equal to each other during the heat accumulating operation. Alternatively, the controller 100 may control the heating medium pump 15 and the water pump 16 such that the heating medium flow rate becomes equal to a value obtained by performing a predetermined correction on the water flow rate during the heat accumulating operation. For example, in a system in which a CO₂ refrigerant is used, an influence of deterioration of COP (Coefficient Of Performance) resulting from an increase in the inlet temperature of the main heat source 6 is more considerable than an influence of deterioration of COP resulting from an increase in the outlet temperature of the main heat source 6 in many cases. In such cases, it is desirable to perform the above correction such that the heating medium flow rate becomes lower than the water flow rate.
In the feedback control during the indoor-heating operation, the controller 100 may substantially fix the circulation flow rate of the heating medium, and may adjust the heating power of the main heat source 6 such that the temperature of the heating medium detected by the main thermistor 25 or the auxiliary thermistor 24 converges to the target value set by the user. During the indoor-heating operation, the controller 100 may change the target value of the heating medium supply temperature in accordance with a difference between the target value of the room temperature and the detected temperature of the room temperature thermistor 28, and control the heating power of the main heat source 6 such that the target value is achieved. Note that, instead of fixing the circulation flow rate of the heating medium, the rotation speed of the heating medium pump 15 may also be fixed.
The auxiliary heat source operation determination section 103 determines whether the operation of the auxiliary heat source 12 is necessary. For example, when a state in which the detected temperature of the main thermistor 25 or the auxiliary thermistor 24 is lower than the target value of the heating medium supply temperature continues for a time period longer than a predetermined time period, the auxiliary heat source operation determination section 103 may determine the activation of the auxiliary heat source 12. When a state in which the frequency of the compressor 7 is not less than a predetermined value and the heating medium supply temperature is lower than the target value continues for a time period longer than a predetermined time period, the auxiliary heat source operation determination section 103 may determine the activation of the auxiliary heat source 12. When a state in which the circulation flow rate of the heating medium is not more than a predetermined value and the heating medium supply temperature is lower than the target value continues for a time period longer than a predetermined time period, the auxiliary heat source operation determination section 103 may determine the activation of the auxiliary heat source 12. When a state in which the detected temperature of the room temperature thermistor 28 is lower than the target value of the room temperature continues for a time period longer than a predetermined time period during the indoor-heating operation, the auxiliary heat source operation determination section 103 may determine the activation of the auxiliary heat source 12.
Fig. 4 is a flowchart of a routine executed by the controller 100 of the heat supply system 1 of Embodiment 1. The controller 100 executes the routine in Fig. 4 periodically repeatedly. In Step S1 in Fig. 4, the main heat source operation determination section 101 determines whether the operation of the main heat source 6 is necessary. In the case where the operation of the main heat source 6 is necessary and the main heat source 6 is not operated, the main heat source operation determination section 101 activates the main heat source 6. Examples of the case where the operation of the main heat source 6 is necessary include the case where the user has started the operation using the remote control 200, the case where a difference between the target value of the room temperature and the detected temperature of the room temperature thermistor 28 is large, and the case where the heat accumulating operation is automatically started. The routine transitions from Step S1 to Step S2. In Step S2, the controller 100 determines whether the main heat source 6 is operated. In the case where the main heat source 6 is not operated, after Step S2, the routine is ended.
In the case where the main heat source 6 is operated, the routine transitions from Step S2 to Step S3. In Step S3, the controller 100 performs a process of determining whether the temperature condition of the heating medium is already stabilized. The detail of the process will be described later. The routine transitions from Step S3 to Step S4. In Step S4, the determination result in Step S3 is checked. In the case where the determination result that the temperature condition of the heating medium is not stabilized yet is obtained, the routine transitions from Step S4 to Step S5. In Step S5, the controller 100 performs the feedback control on at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium based on the detected temperature of the auxiliary thermistor 24. In Step S5, the controller 100 adjusts at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium such that the detected temperature of the auxiliary thermistor 24 converges to the target value of the heating medium supply temperature. The operation in Step S5 is referred to as a "first operation". After Step S5, the routine is ended.
In the case where the determination result that the temperature condition of the heating medium is already stabilized is obtained, the routine transitions from Step S4 to Step S6. In Step S6, the controller 100 performs the feedback control on at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium based on the detected temperature of the main thermistor 25. In Step S6, the controller 100 adjusts at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium such that the detected temperature of the main thermistor 25 converges to the target value of the heating medium supply temperature. The operation in Step S6 is referred to as a "second operation". After Step S6, the routine is ended.
When the main heat source 6 is activated, the auxiliary heat source 12 is not operated and is cold. For a certain time period after the activation of the main heat source 6, heat is removed from the heating medium when the heating medium passes through the auxiliary heat source 12, and the auxiliary heat source 12 is warmed with the heat of the heating medium. During this time period, the heating medium supply temperature detected by the main thermistor 25 is significantly reduced as compared with the outlet temperature of the main heat source 6 detected by the auxiliary thermistor 24. Thereafter, when the temperature of the auxiliary heat source 12 is stabilized, a difference between the detected temperature of the auxiliary thermistor 24 and the detected temperature of the main thermistor 25 is reduced and stabilized. In the process in Step S3 that determines whether the temperature condition of the heating medium is stabilized, it is determined whether the difference between the detected temperature of the auxiliary thermistor 24 and the detected temperature of the main thermistor 25 is stabilized.
Hereinbelow, an example of a method for determining whether the temperature condition of the heating medium is stabilized will be described. In Step S3 described above, it is possible to determine whether the temperature condition of the heating medium is stabilized by methods in the following examples. In a first example, the controller 100 determines whether the temperature condition of the heating medium is stabilized based on an elapsed time from the activation of the main heat source 6. In the case where the elapsed time from the activation of the main heat source 6 has not reached a predetermined time (e.g., one hour), the controller 100 determines that the temperature condition of the heating medium is not stabilized yet. In the case where the elapsed time from the activation of the main heat source 6 has reached the predetermined time, the controller 100 determines that the temperature condition of the heating medium is already stabilized.
Fig. 5 is a flowchart showing a second example of the method for determining whether the temperature condition of the heating medium is stabilized. In the second example, the controller 100 determines whether the temperature condition of the heating medium is stabilized based on the magnitude of a difference between the detected temperature of the auxiliary thermistor 24 and the detected temperature of the main thermistor 25. In Step S10 in Fig. 5, the controller 100 compares the absolute value of the difference between the detected temperature of the auxiliary thermistor 24 and the detected temperature of the main thermistor 25 with a predetermined reference value (e.g., 3°C). In the case where the absolute value of the temperature difference is more than the reference value, the flow transitions from Step S10 to Step S11. In Step S11, the controller 100 determines that the temperature condition of the heating medium is not stabilized yet. In the case where the absolute value of the temperature difference is not more than the reference value, the flow transitions from Step S10 to Step S12. In Step S12, the controller 100 determines that the temperature condition of the heating medium is already stabilized. This second example corresponds to a feature wherein the controller 100 determines the timing of transition from the first operation to the second operation based on the difference between the detected temperature of the auxiliary thermistor 24 and the detected temperature of the main thermistor 25. According to the second example, it is possible to determine whether the temperature condition of the heating medium is stabilized with high accuracy.
Note that, in Step S10 described above, it may be determined whether a state in which the absolute value of the difference between the detected temperature of the auxiliary thermistor 24 and the detected temperature of the main thermistor 25 is not more than the reference value continues for a predetermined time period (e.g., one minute) or longer. In the case where the state does not continue for the predetermined time period or longer, the flow transitions from Step S10 to Step S11. In the case where the state continues for the predetermined time period or longer, the flow transitions from Step S10 to Step S12.
Fig. 6 is a flowchart showing a third example of the method for determining whether the temperature condition of the heating medium is stabilized. In the third example, the controller 100 determines whether the temperature condition of the heating medium is stabilized based on a fluctuation range of the difference between the detected temperature of the auxiliary thermistor 24 and the detected temperature of the main thermistor 25. In Step S15 in Fig. 6, the controller 100 determines whether a state in which the fluctuation range of the absolute value of the difference between the detected temperature of the auxiliary thermistor 24 and the detected temperature of the main thermistor 25 is not more than a predetermined reference value (e.g., 3°C) continues for a predetermined time period (e.g., one minute) or longer. In the case where the state does not continue for the predetermined time period or longer, the flow transitions from Step S15 to Step S16. In Step S16, the controller 100 determines that the temperature condition of the heating medium is not stabilized yet. In the case where the state continues for the predetermined time period or longer, the flow transitions from Step S15 to Step S17. In Step S17, the controller 100 determines that the temperature condition of the heating medium is already stabilized. This third example corresponds to a feature wherein the controller 100 determines the timing of transition from the first operation to the second operation based on the fluctuation range of the difference between the detected temperature of the auxiliary thermistor 24 and the detected temperature of the main thermistor 25. According to the third example, it is possible to determine whether the temperature condition of the heating medium is stabilized with high accuracy.
Fig. 7 is a graph showing an example of the change in the detected temperature of each of the main thermistor 25 and the auxiliary thermistor 24 after the activation of the main heat source 6. The example shown in Fig. 7 is the example in the case where the controller 100 controls at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium based only on the detected temperature of the main thermistor 25 from immediately after the activation of the main heat source 6 without executing the routine in Fig. 4. In the example of the control in Fig. 7, the controller 100 corrects at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium such that the detected temperature of the main thermistor 25 converges to the target value of the heating medium supply temperature from immediately after the activation of the main heat source 6. The example of the control in Fig. 7 does not correspond to Embodiment 1.
For a certain time period after the activation of the main heat source 6, heat is removed from the heating medium while the heating medium passes through the auxiliary heat source 12, and the auxiliary heat source 12 is warmed with the heat of the heating medium. During this time period, the heating medium supply temperature detected by the main thermistor 25 is significantly reduced as compared with the outlet temperature of the main heat source 6 detected by the auxiliary thermistor 24. In the example of the control in Fig. 7, during this time period, at least one of a correction that increases the heating power of the main heat source 6 and a correction that reduces the circulation flow rate of the heating medium is performed in order to cause the detected temperature of the main thermistor 25 to approach the target value. An increase in the detected temperature of the main thermistor 25 tends to lag behind an increase in the outlet temperature of the main heat source 6. A first reason for the lagging is that it takes time for the temperature of the auxiliary heat source 12 having a large heat capacity to increase. A second reason therefor is a delay caused by transferring the heating medium from the outlet of the main heat source 6 to the position of the main thermistor 25. While the increase in the detected temperature of the main thermistor 25 lags, the heating power of the main heat source 6 is corrected to an extremely high value, or the circulation flow rate of the heating medium is corrected to an extremely low value. As a result, the outlet temperature of the main heat source 6 detected by the auxiliary thermistor 24 significantly exceeds the target value, and overshoots. Subsequently to the overshooting of the detected temperature of the auxiliary thermistor 24, the heating medium supply temperature detected by the main thermistor 25 also significantly exceeds the target value, and overshoots. Thus, in the example of the control shown in Fig. 7, both of the detected temperature of the auxiliary thermistor 24 and the detected temperature of the main thermistor 25 significantly exceed the target value, and overshoot. In the example of the control shown in Fig. 7, it is not possible to prevent the overshooting of the heating medium supply temperature. In the example of the control shown in Fig. 7, the load of the main heat source 6 tends to be increased, and hence the life of the main heat source 6 may be reduced.
Fig. 8 is a graph showing an example of the change in the detected temperature of each of the main thermistor 25 and the auxiliary thermistor 24 after the activation of the main heat source 6. The example shown in Fig. 8 is the example in the case where the controller 100 controls at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium based only on the detected temperature of the auxiliary thermistor 24 without using the detected temperature of the main thermistor 25. In the example of the control in Fig. 8, the controller 100 corrects at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium such that the detected temperature of the auxiliary thermistor 24 converges to the target value of the heating medium supply temperature from immediately after the activation of the main heat source 6. The example of the control in Fig. 8 does not correspond to Embodiment 1.
In the example of the control in Fig. 8, after the activation of the main heat source 6, the outlet temperature of the main heat source 6 detected by the auxiliary thermistor 24 converges to the target value of the heating medium supply temperature without significantly overshooting, and is stabilized. After the outlet temperature of the main heat source 6 is stabilized, the heating medium supply temperature detected by the main thermistor 25 is lower than the outlet temperature of the main heat source 6. The reason for that is that the temperature of the heating medium is reduced due to heat dissipation from the heating medium pipe 5 from the main heat source 6 to the position of the main thermistor 25. In the example of the control in Fig. 8, the heating medium supply temperature detected by the main thermistor 25 converges to a temperature lower than the target value, and is stabilized. That is, in the example of the control in Fig. 8, the heating medium supply temperature detected by the main thermistor 25 does not reach the target value, and undershoots.
Fig. 9 is a graph showing an example of the change in the detected temperature of each of the main thermistor 25 and the auxiliary thermistor 24 after the activation of the main heat source 6. The example shown in Fig. 9 is the example in the case where the controller 100 performs control based on the routine shown in Fig. 4. The example of the control in Fig. 9 corresponds to Embodiment 1. A time t1 in Fig. 9 is a time when the controller 100 determines that the temperature condition of the heating medium is already stabilized in Step S3 in Fig. 4. During a time period before the time t1, the controller 100 controls at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium based on the detected temperature of the auxiliary thermistor 24. During the time period before the time t1, the controller 100 corrects at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium such that the detected temperature of the auxiliary thermistor 24 converges to the target value of the heating medium supply temperature. The operation during the time period before the time t1 corresponds to the first operation. In the first operation, the outlet temperature of the main heat source 6 detected by the auxiliary thermistor 24 converges to the target value of the heating medium supply temperature without significantly overshooting. In the first operation, the heating medium supply temperature detected by the main thermistor 25 converges to a temperature lower than the target value.
After the time t1, the controller 100 controls at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium based on the detected temperature of the main thermistor 25. After the time t1, the controller 100 corrects at least one of the heating power of the main heat source 6 and the circulation flow rate of the heating medium such that the detected temperature of the main thermistor 25 converges to the target value of the heating medium supply temperature. The operation after the time t1 corresponds to the second operation. The detected temperature of the main thermistor 25 immediately after the start of the second operation is lower than the target value of the heating medium supply temperature. As a result, the controller 100 performs at least one of the correction that increases the heating power of the main heat source 6 and the correction that reduces the circulation flow rate of the heating medium such that the detected temperature of the main thermistor 25 is increased. With this correction, the heating medium supply temperature detected by the main thermistor 25 converges to the target value and is stabilized without significantly overshooting.
As shown in Fig. 9, according to the present embodiment, the following effects are obtained. It is possible to prevent the overshooting and the undershooting of the heating medium supply temperature. It is possible to avoid an excessive increase in the outlet temperature of the main heat source 6. After the system is stabilized, it is possible to reliably increase the heating medium supply temperature to the heat use terminal to the target value.

Embodiment 2

Next, Embodiment 2 of the present invention will be described with reference to Figs. 10 to 12. Points different from the above-described embodiment will be mainly described, and the same or equivalent portions are designated by the same reference numerals and the description thereof will be omitted. The equipment configuration of the heat supply system 1 of Embodiment 2 is the same as that of Embodiment 1 shown in Figs. 1 to 3, and hence the depiction and description thereof will be omitted.
In the heat supply system 1 of the present embodiment, in the case where it is determined that the heating power of the main heat source 6 is insufficient during the operation of the main heat source 6, similarly to Embodiment 1, the auxiliary heat source operation determination section 103 determines that the auxiliary heat source 12 is activated. When the auxiliary heat source 12 is activated, the heating medium heated by the main heat source 6 is further heated by the auxiliary heat source 12, and the heating medium supply temperature detected by the main thermistor 25 may thereby overshoot. In the present embodiment, when the auxiliary heat source 12 is activated, the controller 100 performs adjustment so as to reduce the heating power of the main heat source 6 such that the overshooting of the heating medium supply temperature detected by the main thermistor 25 is prevented. In the present embodiment, the controller 100 performs the adjustment so as to reduce the heating power of the main heat source 6 concurrently with the activation of the auxiliary heat source 12.
Fig. 10 is a flowchart of a routine executed by the controller 100 of the heat supply system 1 of Embodiment 2. The controller 100 executes the routine in Fig. 10 periodically repeatedly. In Step S20 in Fig. 10, the controller 100 determines whether the main heat source 6 is operated. In the case where the main heat source 6 is not operated, after Step S20, the routine is ended. In the case where the main heat source 6 is operated, the routine transitions from Step S20 to Step S21. In Step S21, the auxiliary heat source operation determination section 103 determines whether the operation of the auxiliary heat source 12 is necessary. The routine transitions from Step S21 to Step S22. In Step S22, the controller 100 determines whether the auxiliary heat source 12 is operated. In the case where the auxiliary heat source 12 is not operated, after Step S22, the routine is ended.
In the case where the auxiliary heat source 12 is operated, the routine transitions from Step S22 to Step S23. In Step S23, the controller 100 determines whether the adjustment of the heating power of the main heat source 6 in the case where the auxiliary heat source 12 is activated is completed. In the case where the adjustment of the heating power of the main heat source 6 is not completed, the routine transitions from Step S23 to Step S24. In Step S24, the controller 100 performs the adjustment of the heating power of the main heat source 6 in the case where the auxiliary heat source 12 is activated. In Step S24, the controller 100 performs the adjustment so as to reduce the heating power of the main heat source 6. In Step S23, in the case where the adjustment of the heating power of the main heat source 6 is already completed, the routine is ended.
Examples of a method according to which the controller 100 performs the adjustment so as to reduce the heating power of the main heat source 6 in Step S24 will be described below.

(Example 1) The heating power of the main heat source 6 is reduced at a predetermined rate. For example, the adjustment is performed such that the frequency of the compressor 7 is reduced to half of the current frequency.
(Example 2) The heating power of the main heat source 6 is reduced at a rate determined based on rated powers of the main heat source 6 and the auxiliary heat source 12. In a situation where the auxiliary heat source 12 is activated, it is possible to assume that the main heat source 6 outputs the rated power. For example, in the case where it is assumed that the rated power of the main heat source 6 is 5 kW and the rated power of the auxiliary heat source 12 is 2 kW, the frequency of the compressor 7 is adjusted to the frequency obtained by multiplying the frequency of the compressor 7 by 3/5 such that the heating power of the main heat source 6 becomes 3 kW.
(Example 3) The heating power of the main heat source 6 required after the activation of the auxiliary heat source 12 is calculated such that the heating medium supply temperature after the activation of the auxiliary heat source 12 reaches the target value, and the heating power of the main heat source 6 is adjusted based on the calculation result. An example of a method for calculating the heating power of the main heat source 6 required after the activation of the auxiliary heat source 12 will be described below. It is assumed that the detected temperature of the main thermistor 25 or the auxiliary thermistor 24 before the heating power of the main heat source 6 is reduced is TH, the detected temperature of the low-temperature thermistor 26 before the heating power of the main heat source 6 is TL, the detected flow rate of the flow rate sensor 27 is Gvw, the target value of the detected temperature of the main thermistor 25 or the auxiliary thermistor 24 is THm, the density of the heating medium is p, and the specific heat of the heating medium is C. A heating power Qn0 of the main heat source 6 before the heating power of the main heat source 6 is reduced can be calculated by the following expression. $Qm 0 = ρ \cdot C \cdot Gvw \cdot (TH - TL)$

It is assumed that the heating power of the auxiliary heat source 12 is Qs, and the heating power of the main heat source 6 required after the activation of the auxiliary heat source 12 is Qm1. Qm1 can be calculated by the following expression. $Qm 1 = ρ \cdot C \cdot Gvw \cdot (THm - TL) - Qs$
In Example 3, in Step S24 in Fig. 10, the heating power of the main heat source 6 is adjusted to Qm1. In order to do so, the heating power of the main heat source 6 may be adjusted so as to be reduced to the heating power obtained by multiplying the heating power of the main heat source 6 by Qm1/Qm0. In order to perform the above adjustment, for example, the frequency of the compressor 7 may be adjusted to the frequency obtained by multiplying the frequency thereof by Qm1/Qm0. By performing the adjustment in this manner, it is possible to cause the heating medium supply temperature after the activation of the auxiliary heat source 12 to approach the target value with high accuracy.
Specific numerical examples are shown below. It is assumed that the detected temperature of the main thermistor 25 or the auxiliary thermistor 24 before the heating power of the main heat source 6 is reduced is 45°C, the detected temperature of the low-temperature thermistor 26 before the heating power of the main heat source 6 is reduced is 30°C, the detected flow rate of the flow rate sensor 27 is 3 liters/minute, the heating power of the auxiliary heat source 12 is 2 kW, and the target value of the detected temperature of the main thermistor 25 or the auxiliary thermistor 24 is 50°C. At this point, the heating power of the main heat source 6 before the heating power of the main heat source 6 is reduced is 3.14 kW, and the heating power of the main heat source 6 required after the activation of the auxiliary heat source 12 is 2.18 kW. In this case, by adjusting the frequency of the compressor 7 to the frequency obtained by multiplying the frequency pf the compressor 7 by 0.69, it is possible to cause the heating medium supply temperature after the activation of the auxiliary heat source 12 to approach the target value 50°C with high accuracy.
Fig. 11 is a graph showing an example of the change in the temperatures in the vicinity of the upstream side and the downstream side of the auxiliary heat source 12 in the case where the auxiliary heat source 12 is activated in a state in which the main heat source 6 is operated and the auxiliary heat source 12 is not operated. The example shown in Fig. 11 is the example in the case where it is assumed that the controller 100 does not execute the process in Step S24 in Fig. 10. That is, the example shown in Fig. 11 is the example in the case where it is assumed that the controller 100 does not perform the adjustment of the heating power of the main heat source 6 resulting from the activation of the auxiliary heat source 12. The example in Fig. 11 does not correspond to Embodiment 2.
The temperature in the vicinity of the downstream side of the auxiliary heat source 12 in Fig. 11 corresponds to the heating medium supply temperature detected by the main thermistor 25. A time t2 in Fig. 11 is a time when the auxiliary heat source 12 is activated. Before the time t2, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 converges to a temperature lower than the target value. Because of this, it is determined that the heating power of the main heat source 6 is insufficient, and the auxiliary heat source 12 is activated. When the auxiliary heat source 12 is activated at the time t2, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 sharply increases, significantly exceeds the target value, and overshoots. The controller 100 detects the overshooting with the main thermistor 25. As a result, by the feedback control of the controller 100, the heating power of the main heat source 6 is corrected so as to be reduced. A time t3 in Fig. 11 is a time when the reduction of the temperature in the vicinity of the upstream side of the auxiliary heat source 12 is started by the correction. With the reduction of the temperature in the vicinity of the upstream side of the auxiliary heat source 12, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 is reduced. Thereafter, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 converges to the target value. In the example shown in Fig. 11, the heating power of the main heat source 6 is not corrected so as to be reduced before the overshooting of the temperature in the vicinity of the downstream side of the auxiliary heat source 12. Accordingly, it is not possible to prevent the overshooting of the temperature in the vicinity of the downstream side of the auxiliary heat source 12, i.e., the heating medium supply temperature.
Fig. 12 is a graph showing an example of the change in the temperatures in the vicinity of the downstream side and the upstream side of the auxiliary heat source 12 in the case where the auxiliary heat source 12 is activated in the state in which the main heat source 6 is operated and the auxiliary heat source 12 is not operated. The example of the control in Fig. 12 is the example in the case where the controller 100 executes the process in Step S24 in Fig. 10. The example of the control in Fig. 12 corresponds to Embodiment 2.
A time t4 in Fig. 12 is a time when the auxiliary heat source 12 is activated. Before the time t4, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 converges to a temperature lower than the target value. Because of this, it is determined that the heating power of the main heat source 6 is insufficient, and the auxiliary heat source 12 is activated. Concurrently with the activation of the auxiliary heat source 12, with the process in Step S24 in Fig. 10, the adjustment that reduces the heating power of the main heat source 6 is performed. With this, soon after the activation of the auxiliary heat source 12, the temperature in the vicinity of the upstream side of the auxiliary heat source 12 is reduced. As a result, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 is prevented from significantly exceeding the target value. That is, the overshooting of the heating medium supply temperature is prevented.
In a system in which the heat pump of the main heat source 6 uses the CO₂ refrigerant, there are cases where the circulation flow rate of the heating medium is set to be low for the purpose of obtaining high COP. In general, in such a system, the heating medium supply temperature tends to overshoot when the auxiliary heat source 12 is activated. According to Embodiment 2, even in the system, it is possible to reliably prevent the overshooting of the heating medium supply temperature when the auxiliary heat source 12 is activated.

Embodiment 3

Next, Embodiment 3 of the present invention will be described with reference to Figs. 13 to 15. Points different from the embodiments described above will be mainly described, and the same or equivalent portions are designated by the same reference numerals and the description thereof will be omitted. The equipment configuration of the heat supply system 1 of Embodiment 3 is the same as that of Embodiment 1 shown in Figs. 1 to 3, and hence the depiction and description thereof will be omitted.
In the heat supply system 1 of the present embodiment, in the case where it is determined that the heating power of the main heat source 6 is insufficient during the operation of the main heat source 6, similarly to Embodiment 1, the auxiliary heat source operation determination section 103 determines that the auxiliary heat source 12 is activated. In Embodiment 2 described above, concurrently with the activation of the auxiliary heat source 12, the controller 100 performs the adjustment so as to reduce the heating power of the main heat source 6. In contrast to this, in the present embodiment, the controller 100 performs the adjustment so as to reduce the heating power of the main heat source 6 before the activation of the auxiliary heat source 12. In a system in which the length of a flow path from the main heat source 6 to the auxiliary heat source 12 is large, it takes time for an effect of the adjustment that reduces the heating power of the main heat source 6 to reach the position of the auxiliary heat source 12. That is, in the system in which the length of the flow path from the main heat source 6 to the auxiliary heat source 12 is large, it takes time for the temperature in the vicinity of the upstream side of the auxiliary heat source 12 to start its reduction after the heating power of the main heat source 6 is reduced. In the present embodiment, in the case where it is determined that the auxiliary heat source 12 is activated during the operation of the main heat source 6, after the controller 100 performs the adjustment so as to reduce the heating power of the main heat source 6, the controller 100 temporarily halts the activation of the auxiliary heat source 12 until the effect reaches the position of the auxiliary heat source 12. The controller 100 activates the auxiliary heat source 12 after the effect of the adjustment of the heating power of the main heat source 6 reaches the position of the auxiliary heat source 12. According to the present embodiment, even in the system in which the length of the flow path from the main heat source 6 to the auxiliary heat source 12 is large, it is possible to reliably prevent the overshooting of the heating medium supply temperature when the auxiliary heat source 12 is activated.
Fig. 13 is a flowchart of a routine executed by the controller 100 of the heat supply system 1 of Embodiment 3. The controller 100 executes the routine in Fig. 13 periodically repeatedly. In Step S30 in Fig. 13, the controller 100 determines whether the main heat source 6 is operated. In the case where the main heat source 6 is not operated, after Step S30, the routine is ended. In the case where the main heat source 6 is operated, the routine transitions from Step S30 to Step S31. In Step S31, the auxiliary heat source operation determination section 103 determines whether the operation of the auxiliary heat source 12 is necessary. The routine transitions from Step S31 to Step S32. In Step S32, the controller 100 determines whether the operation of the auxiliary heat source 12 is determined. In the case where the auxiliary heat source 12 is not operated, after Step S32, the routine is ended.
In the case where the operation of the auxiliary heat source 12 is determined, the routine transitions from Step S32 to Step S33. In Step S33, the controller 100 determines whether the adjustment of the heating power of the main heat source 6 before the auxiliary heat source 12 is activated is completed. In the case where the adjustment of the heating power of the main heat source 6 is not completed, the routine transitions from Step S33 to Step S34. In Step S34, the controller 100 performs the adjustment of the heating power of the main heat source 6 before the auxiliary heat source 12 is activated. In Step S34, the controller 100 performs the adjustment so as to reduce the heating power of the main heat source 6. The adjustment method in Step S34 is the same as the adjustment method in Step S24 in Embodiment 2 described above. The routine transitions from Step S34 to Step S35. In Step S35, the controller 100 temporarily halts the activation of the auxiliary heat source 12. After Step S35, the routine is ended.
In Step S33, in the case where the adjustment of the heating power of the main heat source 6 is already completed, the routine transitions to Step S36. In Step S36, the controller 100 determines whether the effect of the adjustment of the heating power of the main heat source 6 has reached the position of the auxiliary heat source 12. In the case where it is determined that the effect of the adjustment of the heating power of the main heat source 6 has not reached the position of the auxiliary heat source 12 yet, the routine transitions from Step S36 to Step S37. In Step S37, the controller 100 temporarily halts the activation of the auxiliary heat source 12. After Step S37, the routine is ended.
In Step S36, in the case where it is determined that the effect of the adjustment of the heating power of the main heat source 6 has reached the position of the auxiliary heat source 12, the routine transitions from Step S36 to Step S38. In Step S38, the controller 100 activates the auxiliary heat source 12. In Step S38, in the case where the auxiliary heat source 12 is already activated, the controller 100 continues the operation of the auxiliary heat source 12. After Step S38, the routine is ended.
Fig. 14 is a graph showing an example of the change in the temperatures in the vicinity of the downstream side and the upstream side of the auxiliary heat source 12 in the case where the auxiliary heat source 12 is activated in the state in which the main heat source 6 is operated and the auxiliary heat source 12 is not operated. The example shown in Fig. 14 is the example in the case where it is assumed that the adjustment of the heating power of the main heat source 6 is performed concurrently with the activation of the auxiliary heat source 12 in the system in which the length of the flow path from the main heat source 6 to the auxiliary heat source 12 is large.
The temperature in the vicinity of the downstream side of the auxiliary heat source 12 in Fig. 14 corresponds to the heating medium supply temperature detected by the main thermistor 25. A time t5 in Fig. 14 is a time when the auxiliary heat source 12 is activated and the adjustment that reduces the heating power of the main heat source 6 is performed. Before the time t5, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 converges to a temperature lower than the target value. Because of this, it is determined that the heating power of the main heat source 6 is insufficient, and the auxiliary heat source 12 is activated. It takes time for the temperature in the vicinity of the upstream side of the auxiliary heat source 12 to start its reduction after the heating power of the main heat source 6 is adjusted so as to be reduced at the time t5. For a certain time period after the activation of the auxiliary heat source 12, the temperature in the vicinity of the upstream side of the auxiliary heat source 12 is equal to the temperature before the adjustment of the heating power of the main heat source 6. Accordingly, when the auxiliary heat source 12 heats the heating medium, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 sharply increases, and overshoots. A time t6 in Fig. 14 is a time when the effect of the adjustment of the heating power of the main heat source 6 reaches the position of the auxiliary heat source 12. That is, the time t6 is the time when the temperature in the vicinity of the upstream side of the auxiliary heat source 12 starts its reduction. Thereafter, with the reduction of the temperature in the vicinity of the upstream side of the auxiliary heat source 12, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 is reduced.
Fig. 15 is a graph showing an example of the change in the temperatures in the vicinity of the downstream side and the upstream side of the auxiliary heat source 12 in the case where the auxiliary heat source 12 is activated in the state in which the main heat source 6 is operated and the auxiliary heat source 12 is not operated. The example of the control in Fig. 15 is the example in the case where the controller 100 executes the routine in Fig. 13. The example of the control in Fig. 15 corresponds to Embodiment 3.
A time t7 in Fig. 15 is a time when the activation of the auxiliary heat source 12 is determined. Before the time t7, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 converges to a temperature lower than the target value. Because of this, it is determined that the heating power of the main heat source 6 is insufficient, and the activation of the auxiliary heat source 12 is determined. When the activation of the auxiliary heat source 12 is determined, with the process in Step S34 in Fig. 13, the adjustment that reduces the heating power of the main heat source 6 is performed. With this, the temperature in the vicinity of the downstream side of the main heat source 6 is reduced. A time t8 in Fig. 15 is a time when the effect of the adjustment of the heating power of the main heat source 6 reaches the position of the auxiliary heat source 12. That is, the time t8 is the time when the temperature in the vicinity of the upstream side of the auxiliary heat source 12 starts its reduction. At the time t8, the auxiliary heat source 12 is activated. When the auxiliary heat source 12 is activated, the reduction of the temperature in the vicinity of the upstream side of the auxiliary heat source 12 is already started. Accordingly, after the activation of the auxiliary heat source 12, the temperature in the vicinity of the downstream side of the auxiliary heat source 12 is prevented from significantly exceeding the target value. That is, the overshooting of the heating medium supply temperature is prevented.
In the system in which the heat pump of the main heat source 6 uses the CO2 refrigerant, there are cases where the circulation flow rate of the heating medium is set to be low for the purpose of obtaining high COP. In general, in such a system, the heating medium supply temperature tends to overshoot when the auxiliary heat source 12 is activated. According to Embodiment 3, even in the system, it is possible to reliably prevent the overshooting of the heating medium supply temperature when the auxiliary heat source 12 is activated.
Examples of a method according to which the controller 100 determines whether the effect of the adjustment of the heating power of the main heat source 6 has reached the position of the auxiliary heat source 12 in Step S36 will be described below.

(Example 1) The controller 100 can determine whether the effect of the adjustment of the heating power of the main heat source 6 has reached the position of the auxiliary heat source 12 based on an elapsed time after the adjustment of the heating power of the main heat source 6. For example, the controller 100 determines that the effect of the adjustment of the heating power of the main heat source 6 has not reached the position of the auxiliary heat source 12 in the case where the elapsed time has not reached a predetermined time (e.g., 30 minutes), and the controller 100 determines that the effect of the adjustment of the heating power of the main heat source 6 has reached the position of the auxiliary heat source 12 in the case where the elapsed time has reached the predetermined time. In the case of Example 1, the controller 100 activates the auxiliary heat source 12 in response to the elapsed time after the reduction of the heating power of the main heat source 6 having reached the predetermined time.
(Example 2) The controller 100 can determine whether the effect of the adjustment of the heating power of the main heat source 6 has reached the position of the auxiliary heat source 12 based on a detected temperature of a temperature sensor disposed in the vicinity of the downstream side or the upstream side of the auxiliary heat source 12. In the case of the configuration example in Fig. 1, it is possible to use the main thermistor 25 as the temperature sensor. For example, in the case where the detected temperature is reduced by a predetermined amount (e.g., 3°C) or more as compared with the detected temperature before the adjustment of the heating power of the main heat source 6, the controller 100 determines that the effect of the adjustment of the heating power of the main heat source 6 has reached the position of the auxiliary heat source 12. In the case of Example 2, the controller 100 activates the auxiliary heat source 12 in response to the reduction of the detected temperature by the predetermined amount (e.g., 3°C) or more as compared with the detected temperature before the adjustment of the heating power of the main heat source 6. In addition, in the case where the detected temperature is significantly reduced in a short time period (e.g., in the case where the detected temperature is reduced by 3°C or more in one minute), the controller 100 may determine that the effect of the adjustment of the heating power of the main heat source 6 has reached the position of the auxiliary heat source 12.
(Example 3) It is assumed that the detected flow rate of the flow rate sensor 27 is Gvw, the target value of the heating medium supply temperature is THm, the density of the heating medium is p, the specific heat of the heating medium is C, and the heating power of the auxiliary heat source 12 is Qs. When the detected temperature of the temperature sensor disposed in the vicinity of the downstream side or the upstream side of the auxiliary heat source 12 becomes equal to or close to (THm - Qs/ρ/C/Gvw), the controller 100 determines that the effect of the adjustment of the heating power of the main heat source 6 has reached the position of the auxiliary heat source 12, and activates the auxiliary heat source 12. According to Example 3, it is possible to immediately cause the heating medium supply temperature to converge to the target value THm after the activation of the auxiliary heat source 12.
(Example 4) In the case where a difference between the detected temperature of the main thermistor 25 and the detected temperature of the auxiliary thermistor 24 is stabilized, the controller 100 determines that the effect of the adjustment of the heating power of the main heat source 6 has reached the position of the auxiliary heat source 12, and activates the auxiliary heat source 12. According to Example 4, it is possible to reliably prevent both of the overshooting and the undershooting of the heating medium supply temperature.

Thus, the embodiments of the present invention have been described, and a plurality of the embodiments described above may be arbitrarily combined and implemented in the present invention.

[Reference Signs List]

1: heat supply system
2: first unit
3: second unit
4, 5: heating medium pipe
6: main heat source
7: compressor
8: high-temperature side heat exchanger
9: decompression device
10: low-temperature side heat exchanger
11: blower
12: auxiliary heat source
13: hot water tank
14: hot water supply heat exchanger
15: heating medium pump
16: water pump
17: switching valve
18: water supply pipe
19: hot water supply pipe
20: hot water faucet
21: indoor-heating appliance
22, 23: heating medium pipe
24: auxiliary thermistor
25: main thermistor
26: low-temperature thermistor
27: flow rate sensor
28: room temperature thermistor
30a, 30b, 30c: hot water temperature sensor
40: water source
100: controller
101: main heat source operation determination section
102: main heat source power control section
103: auxiliary heat source operation determination section
104: heating medium pump control section
105: water pump control section
200: remote control
1000: processor
1001: memory

Claims

A heat supply system (1) comprising:
a pump (15) configured to pump a heating medium;

a first heating device (6) configured to heat the heating medium;

a second heating device (12) configured to heat the heating medium downstream of the first heating device (6); and

a controller (100) ; characterized in that the controller (100) is configured to reduce a heating power of the first heating device (6) concurrently with or before activation of the second heating device (12), in a case where the second heating device (12) is activated in a state in which the first heating device (6) is operated without operating the second heating device (12).
The heat supply system (1) according to claim 1, wherein
the controller (100) is configured to activate the second heating device (12) based on an elapsed time after the heating power of the first heating device (6) is reduced, or in response to a change in a temperature of the heating medium downstream of the first heating device (6) after the heating power of the first heating device (6) is reduced.
The heat supply system (1) according to claim 1 or 2, wherein
the controller (100) is configured to change an amount of the reduction of the heating power of the first heating device (6) in accordance with the temperature of the heating medium upstream of the first heating device (6) and the temperature of the heating medium downstream of the first heating device (6) before the heating power of the first heating device (6) is reduced, a flow rate of the heating medium, a target value of the temperature of the heating medium downstream of the second heating device (12), and a heating power of the second heating device (12).
The heat supply system (1) according to any one of claims 1 to 3, further comprising:
a first unit (2) in which the first heating device (6) is housed;

a second unit (3) in which the second heating device (12) is housed; and

a heating medium (4, 5) pipe that connects the first unit (2) and the second unit (3).
The heat supply system (1) according to any one of claims 1 to 4, wherein
the first heating device (6) comprises a heat pump that uses carbon dioxide as a refrigerant.