JP2021081169A - Heating system and control method of the same - Google Patents

Abstract

To provide a heating system in which efficiency has been further improved.SOLUTION: A heating system includes: a heat exchange part for heating a liquid to be heated and discharging it from an outlet; a circulation flow passage connected to an inlet and the outlet of the heat exchange part, and connected to a heating load for cooling the liquid to be heated by heat exchange of the liquid to be heated; a return flow passage for connecting the circulation flow passage between the inlet side and the outlet side of the heating load; a circulation pump provided at the outlet side of the heating load in the circulation flow passage and between the return flow passage and the heating load, and capable of changing the discharge flow rate; a flow rate adjustment part for adjusting the flow rate of the liquid to be heated flowing in the heat exchange part; and a control device. The control device includes a first control part which adjusts the discharge flow rate of the circulation pump based on a temperature difference between the inlet side and the outlet side of the heating load, and operates the flow rate adjustment part so that the flow rate flowing into the heat exchange part becomes equal to or greater than a lower limit, irrespective of the change in the discharge flow rate.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a heating system and a method for controlling the heating system.

For example, as a technique for operating a heating device such as floor heating, the device described in Patent Document 1 below is known. The heating device described in Patent Document 1 has a water heater that supplies hot water to a floor heating panel as a heating load. The water heater has a tank and a heat pump. The water heater is configured to always supply hot water at a constant temperature. Specifically, the temperature inside the tank is maintained at a predetermined value by detecting the temperature of the upper part of the tank and controlling the compressor and the pump of the heat pump. Furthermore, by controlling the three-way valve, the mixing ratio of the relatively cold water returning to the heat pump through the return flow path and the relatively warm water flowing out of the tank is changed. As a result, hot water at the target temperature is supplied to the heating load.

JP-A-2018-169108

However, in the heating device described in Patent Document 1, since it is necessary to continue to store hot water in the tank, the heat of hot water easily escapes to the outside through the tank. Furthermore, hot water at a constant temperature is always supplied from the tank. In other words, even when the heating load is small (that is, even when the temperature of the hot water does not have to be high), hot water at a constant temperature is supplied. Therefore, the compressor of the heat pump cannot be operated at an efficient operation point. Therefore, the efficiency of the heating device may be limited.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a heating system having further improved efficiency and a control method thereof.

In order to solve the above problems, the heating system according to the present disclosure has a refrigerant circuit in which CO2 as a refrigerant repeatedly condenses and evaporates and circulates, and heats the liquid to be heated introduced from the inlet and discharges it from the outlet. The heat exchange unit and the liquid to be heated circulate and are connected to the inlet and outlet of the heat exchange unit, and are connected to a heating load that cools the liquid to be heated by heat exchange with the liquid to be heated. A return flow path that connects the circulation flow path between the inlet side and the outlet side of the heating load, and the outlet side of the heating load in the circulation flow path, and the return. A circulation pump provided between the flow path and the heating load and capable of pumping the liquid to be heated and changing the discharge flow rate, and a circulation pump provided in the circulation flow path and flowing into the heat exchange unit. A flow rate adjusting unit for adjusting the flow rate of the liquid to be heated, a circulation pump, and a control device for controlling the flow rate adjusting unit are provided, and the control device is a control device for the liquid to be heated on the inlet side of the heating load. The discharge flow rate of the circulation pump is adjusted based on the difference between the temperature and the temperature on the outlet side, and the flow rate of the liquid to be heated flowing into the heat exchange unit is predetermined regardless of the change in the discharge flow rate. It has a first control unit that operates the flow rate adjusting unit so as to be equal to or higher than the lower limit value.

The control method of the heating system according to the present disclosure has a refrigerant circuit in which CO2, which is a refrigerant, circulates by repeating a thermal change or condensation and evaporation, and heats a liquid to be heated introduced from an inlet and discharges it from an outlet. The heat exchange unit and the liquid to be heated circulate and are connected to the inlet and outlet of the heat exchange unit, and are connected to a heating load that cools the liquid to be heated by heat exchange with the liquid to be heated. The return flow path connecting the circulation flow path between the inlet side and the outlet side of the heating load, and the outlet side of the heating load in the circulation flow path, and the return flow. A circulation pump provided between the path and the heating load and capable of pumping the liquid to be heated and changing the discharge flow rate, and a circulation pump provided in the circulation flow path and flowing into the heat exchange unit. A control method for a heating system including a flow rate adjusting unit for adjusting the flow rate of the liquid to be heated, which calculates a difference between the temperature of the liquid to be heated on the inlet side of the heating load and the temperature on the outlet side. The steps, the pump adjusting step for adjusting the discharge flow rate of the circulation pump based on the difference, and the flow rate of the liquid to be heated flowing into the heat exchange unit are predetermined regardless of the change in the discharge flow rate. It includes a flow rate adjusting step of operating the flow rate adjusting unit so as to be equal to or higher than the lower limit value.

According to the present disclosure, it is possible to provide a heating system having further improved efficiency and a control method thereof.

It is a system diagram which shows the structure of the heating system which concerns on embodiment of this disclosure. It is a hardware block diagram of the control device which concerns on embodiment of this disclosure. It is a functional block diagram of the control device which concerns on embodiment of this disclosure. It is a flowchart which shows the operation of the 1st control part which concerns on embodiment of this disclosure. It is a flowchart which shows the operation of the 2nd control part which concerns on embodiment of this disclosure. It is a system diagram which shows the structure of the heating system which concerns on the modification of this disclosure.

(Structure of heating system)
Hereinafter, the heating system 100 according to the embodiment of the present disclosure will be described with reference to FIGS. 1 to 5. The heating system 100 according to the present embodiment is, for example, a device that supplies hot water to the floor heating panel as the heating load 2. As shown in FIG. 1, the heating system 100 includes a heat exchange unit 1, a circulation flow path 3, a return flow path 4, a circulation pump 5, a flow rate adjusting unit 6, a first temperature detection unit 71, and a first. It includes a two-temperature detection unit 72, a third temperature detection unit 73, and a control device 90.

(Structure of heat exchange unit)
The heat exchange unit 1 heats water or the like as a liquid to be heated. More specifically, the heat exchange unit 1 circulates CO2, which is a refrigerant, while repeating sensible heat change or condensation and evaporation, and causes heat exchange between the liquid to be heated and CO2. As a result, the heated liquid to be heated is discharged from the outlet 1b of the heat exchange unit 1. Although not shown in detail, the heat exchange unit 1 is a heat pump having a compressor, an expansion valve, a condenser, an evaporator, and the like inside.

(Composition of circulation flow path)
A circulation flow path 3 is connected to the outlet 1b and the inlet 1a of the heat exchange unit 1. The circulation flow path 3 is a pipeline from the outlet 1b of the heat exchange unit 1 to the inlet 1a through the outside of the heat exchange unit 1. The above-mentioned liquid to be heated flows through the circulation flow path 3. A heating load 2 is connected in the middle of the circulation flow path 3. The high-temperature liquid to be heated supplied to the inlet 2a of the heating load 2 through the circulation flow path 3 is cooled by exchanging heat with the room air in the heating load 2, and is discharged from the outlet 2b to the circulation flow path 3.

(Structure of return flow path)
A return flow path 4 is provided between the inlet 2a and the outlet 2b of the heating load 2 in the circulation flow path 3. That is, the return flow path 4 is configured to take out a part of the liquid to be heated flowing through the circulation flow path 3 and bypass the heat exchange unit 1.

(Circulation pump configuration)
A circulation pump 5 is provided between the return flow path 4 and the heating load 2 on the outlet 2b side of the heating load 2 in the circulation flow path 3. The circulation pump 5 pumps the liquid to be heated in the circulation flow path 3 from the outlet 2b side of the heating load 2 toward the inlet 1a side of the heat exchange section 1. Further, the circulation pump 5 can continuously change the discharge flow rate based on an external command, and specifically, the rotation speed can be changed based on the input voltage. Inverter pump is preferably used as the circulation pump 5. As will be described in detail later, the discharge flow rate of the circulation pump 5 is controlled by a command from the control device 90.

(Valve gear configuration)
Further, a valve device V1 as a flow rate adjusting unit 6 is provided on the circulation flow path 3 between the inlet 4a of the return flow path 4 and the inlet 1a of the heat exchange unit 1. The valve device V1 can adjust the flow rate of the fluid (liquid to be heated) passing through the valve device V1 by continuously changing the opening degree based on a command from the outside.

(Structure of the first temperature detector)
A first temperature detection unit 71 is provided between the valve device V1 and the inlet 1a of the heat exchange unit 1. The first temperature detection unit 71 detects the temperature of the liquid to be heated flowing in the circulation flow path 3 and sends it to the control device 90 as an electric signal. As the first temperature detection unit 71, a known temperature sensor or the like is preferably used.

(Structure of the second temperature detector)
A second temperature detection unit 72 is provided between the outlet 4b of the return flow path 4 and the inlet 2a of the heating load 2. Similar to the first temperature detection unit 71, the second temperature detection unit 72 detects the temperature of the liquid to be heated flowing in the circulation flow path 3 and sends it to the control device 90 as an electric signal. As the second temperature detection unit 72, a known temperature sensor or the like is preferably used.

(Structure of third temperature detector)
A third temperature detection unit 73 is provided between the circulation pump 5 and the outlet 2b of the heating load 2. Similar to the first temperature detection unit 71 and the second temperature detection unit 72, the third temperature detection unit 73 detects the temperature of the liquid to be heated flowing in the circulation flow path 3 and sends the control device 90 as an electric signal. Send out. As the third temperature detection unit 73, a known temperature sensor or the like is preferably used.

(Control device configuration)
Next, the configuration of the control device 90 will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, the control device 90 includes a CPU 91 (Central Processing Unit), a ROM 92 (Read Only Memory), a RAM 93 (Random Access Memory), an HDD 94 (Hard Disk Drive), and a signal transmission / reception module 95 (I / O: Input). / Output). The signal transmission / reception module 95 receives the value of the temperature detected by the first temperature detection unit 71, the second temperature detection unit 72, and the third temperature detection unit 73 as an electric signal. Further, the signal transmission / reception module 95 transmits an electric signal for controlling these devices to the heat exchange unit 1, the circulation pump 5, and the valve device V1 described above. The signal transmission / reception module 95 may transmit / receive an amplified signal via, for example, a charge amplifier or the like.

As shown in FIG. 4, the CPU 91 of the control device 90 has a first control unit 81, a second control unit 82, a storage unit 83, and a determination unit 84 by executing a program stored in the own device in advance. The first control unit 81 adjusts the discharge flow rate of the circulation pump 5 based on the difference in temperature of the liquid to be heated at the inlet 2a side and the outlet 2b side of the heating load 2. Further, the first control unit 81 makes the flow rate of the liquid to be heated flowing into the heat exchange unit 1 a constant value equal to or more than a predetermined lower limit value and less than or equal to the upper limit value regardless of the change in the discharge flow rate. The opening degree of the valve device V1 is adjusted. The storage unit 83 stores these lower limit values and upper limit values in advance.

The second control unit 82 controls the output of the heat exchange unit 1. Although not shown in detail, the heat exchange unit 1 has a compressor that compresses the liquid to be heated. The temperature of the liquid to be heated discharged from the heat exchange unit 1 is proportional to the rotation speed of this compressor. That is, by changing the rotation speed of the compressor by the second control unit 82, the temperature of the liquid to be heated discharged from the heat exchange unit 1 (more specifically, the second temperature is detected on the inlet 2a side of the heating load 2). The temperature detected by the unit 72) is adjusted toward a predetermined target temperature (inlet target temperature Tp). The storage unit 83 stores the inlet target temperature Tp in advance or holds it based on an input from the outside.

(Operation of control device)
Next, an example of control by the control device 90 (control method of the heating system 100) will be described with reference to FIGS. 4 and 5.

(Operation of the first control unit)
As shown in FIG. 4, the control method of the circulation pump 5 and the valve device V1 by the first control unit 81 includes an operation state determination step S11, a difference calculation step S12, a determination step S13, and pump adjustment steps S14A and S14B. , The flow rate adjusting steps S15A and S15B are included.

In the operation state determination step S11, the determination unit 84 determines whether or not the heating system 100 is operated under the control of the first control unit 81. If Yes is determined in the operating state determination step S11, the subsequent difference calculation step S12 is executed. In the difference calculation step S12, the temperature difference (ΔT = T1-T2) of the liquid to be heated between the inlet 2a side and the outlet 2b side of the heating load 2 is calculated. Specifically, the difference ΔT between the values detected by the second temperature detection unit 72 and the third temperature detection unit 73 is calculated.

In the determination step S13, the determination unit 84 determines whether or not the difference ΔT is equal to or greater than a predetermined threshold value. The state in which the difference ΔT is equal to or greater than the threshold value (step S13: Yes) means that the heat drop in the heating load 2 is changing in the direction of increasing. Therefore, in this state, it is necessary to increase the amount of heat of the liquid to be heated supplied to the heating load 2. Therefore, by executing the subsequent pump adjustment step 14A, the discharge flow rate of the circulation pump 5 is increased. Further, by executing the flow rate adjusting step S15A, the opening degree of the valve device V1 is reduced. As a result, first, the flow rate of the liquid to be heated supplied to the inlet 2a side of the heating load 2 increases, and the output of the heating load 2 increases.

Here, consider a case where the flow rate adjusting step S15A is not executed (that is, a case where the opening degree of the valve device V1 is not changed). When such control is performed, the flow rate of the liquid to be heated flowing into the heat exchange unit 1 also increases as the discharge flow rate of the circulation pump 5 increases. Various devices and pipes constituting the heat exchange unit 1 have predetermined pressure resistance and corrosion resistance. Therefore, if the flow rate of the liquid to be heated flowing into the heat exchange unit 1 is increased endlessly, there is a risk of erosion or damage to these devices and pipes. Therefore, the opening degree of the valve device V1 is reduced by executing the above-mentioned flow rate adjusting step S15A. As a result, the flow rate toward the return flow path 4 side becomes relatively large, while the flow rate toward the heat exchange unit 1 can be maintained below a certain value (upper limit value). The "upper limit value" is appropriately determined according to the performance and specifications of the heat exchange unit 1.

On the contrary, the state where the difference ΔT is less than the threshold value (step S13: No) means that the heat drop in the heating load 2 is changing in the direction of becoming smaller. Therefore, in this state, it is necessary to reduce the amount of heat of the liquid to be heated supplied to the heating load 2. Therefore, by executing the subsequent pump adjustment step S14B, the discharge flow rate of the circulation pump 5 is reduced. Further, by executing the flow rate adjusting step S15B, the opening degree of the valve device V1 is increased. As a result, the flow rate of the liquid to be heated supplied to the inlet 2a side of the heating load 2 first decreases, and the output of the heating load 2 decreases.

Here, consider a case where the flow rate adjusting step S15B is not executed (that is, a case where the opening degree of the valve device V1 is not changed). When such control is performed, the flow rate of the liquid to be heated flowing into the heat exchange unit 1 also decreases as the discharge flow rate of the circulation pump 5 decreases. It becomes necessary to continue heating the liquid to be heated with a small flow rate to a higher temperature state. As a result, the efficient operation of the heat exchange unit 1 may be hindered (the optimum operating point may be deviated). Therefore, the opening degree of the valve device V1 is increased by executing the above-mentioned flow rate adjusting step S15B. As a result, the flow rate toward the return flow path 4 side becomes relatively small, while the flow rate toward the heat exchange unit 1 can be maintained at a certain value (lower limit value) or more. The "lower limit value" is appropriately determined according to the performance and specifications of the heat exchange unit 1.

(Operation of the second control unit)
Next, the operation of the second control unit 82 will be described with reference to FIG. The control method of the heat exchange unit 1 by the second control unit 82 includes an operation state determination step S21, an inlet temperature acquisition step S22, a temperature determination step S23, and output adjustment steps S24A and S24B.

In the operation state determination step S21, the determination unit 84 determines whether or not the heating system 100 is being operated under the control of the second control unit 82. If Yes is determined in the operating state determination step S21, the subsequent inlet temperature acquisition step S22 is executed. In the inlet temperature acquisition step S22, first, the temperature T0 of the liquid to be heated at the inlet 1a side of the heat exchange unit 1 is acquired based on the detection result of the first temperature detection unit 71 described above. Next, the above-mentioned temperature difference ΔT (= T1-T2: temperature difference between the inlet 2a side and the outlet 2b side of the heating load 2) is added to this temperature T0. As a result, the predicted temperature value Ts = T0 + ΔT can be obtained.

Next, in the temperature determination step S23, the determination unit 84 determines the magnitude of the temperature prediction value Ts and the predetermined inlet target temperature Tp. When it is determined in the temperature determination step S23 that Ts ≦ Tp (step S23: Yes), the output of the heat exchange unit 1 is increased by executing the subsequent output adjustment step S24A. Specifically, the rotation speed of the compressor of the heat exchange unit 1 is increased. On the other hand, when it is determined in the temperature determination step S23 that Ts> Tp (step S23: No), the output of the heat exchange unit 1 is reduced by executing the subsequent output adjustment step S24B. Specifically, the rotation speed of the compressor of the heat exchange unit 1 is reduced. By performing such control, the temperature of the liquid to be heated at the inlet 2a of the heating load 2 is adjusted so as to approach the inlet target temperature Tp.

(Action effect)
As described above, according to the above configuration, the first control unit 81 of the control device 90 is based on the difference between the temperature of the liquid to be heated on the inlet 2a side of the heating load 2 and the temperature on the outlet 2b side. Adjust the discharge flow rate of the circulation pump 5. For example, when the temperature difference changes in the direction of decreasing (that is, the amount of heat required by the heating load 2 changes in the direction of decreasing), the first control unit 81 sets the discharge flow rate of the circulation pump 5. Change in the direction of decrease. Further, at this time, in the valve device V1 as the flow rate adjusting unit, the flow rate of the liquid to be heated flowing into the heat exchange unit 1 is equal to or higher than a predetermined lower limit value regardless of the change in the discharge flow rate of the circulation pump 5. The opening is adjusted to. As a result, the temperature difference between the inlet 2a side and the outlet 2b side of the heating load 2 becomes large, and this can be maintained at a constant value. Further, even when the amount of heat required by the heating load 2 is reduced in this way, a flow rate equal to or higher than the lower limit value is supplied to the heat exchange unit 1. As a result, the heat exchange unit 1 can be operated at the optimum operating point. On the other hand, when the flow rate flowing into the heat exchange unit 1 is also infinitely reduced as the amount of heat required by the heating load 2 is reduced, the liquid to be heated with a small flow rate is heated to a higher temperature state. It will be necessary to continue to do so. This may hinder the efficient operation of the heat exchange unit 1. However, according to the above configuration, such a possibility can be reduced and the heat exchange unit 1 can be operated reasonably and stably.

According to the above configuration, the first control unit 81 operates the valve device V1 as the flow rate adjusting unit 6 so that the flow rate of the liquid to be heated flowing into the heat exchange unit 1 is equal to or less than a predetermined upper limit value. Here, in the various pipes and equipment of the heat exchange unit 1, if the flow rate exceeds a certain level, erosion may occur. However, according to the above configuration, since the upper limit value is provided for the flow rate, such a possibility can be reduced.

According to the above configuration, the valve device V1 is used as the flow rate adjusting unit 6, and the opening degree of the valve device V1 is changed by the first control unit 81, so that the liquid to be heated flowing into the heat exchange unit 1 can be easily and inexpensively charged. The flow rate can be greater than or equal to a predetermined lower limit.

According to the above configuration, the second control unit 82 changes the output of the heat exchange unit 1 so that the temperature of the liquid to be heated at the inlet 2a of the heating load 2 becomes the inlet target temperature. As a result, even when the inlet target temperature changes, the temperature of the liquid to be heated can be immediately followed with high responsiveness.

(Other embodiments)
Although the embodiments of the present disclosure have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like within a range not deviating from the gist of the present disclosure are also included.
For example, as shown in FIG. 6, a three-way valve V2 can be used as the flow rate adjusting unit 6 instead of the valve device V1 described in the above embodiment. Specifically, the three-way valve V2 is provided at the outlet 4b of the return flow path 4. Further, in this configuration, a flow rate measuring unit 80 for measuring the flow rate of the liquid to be heated is provided between the inlet 4a of the return flow path 4 and the inlet 1a of the heat exchange unit 1. The control device 90 (first control unit 81) changes the opening degree of the three-way valve V2 based on the value of the flow rate measured by the flow rate measuring unit 80, so that the flow rate flowing into the return flow path 4 and the heat exchange unit Adjust the ratio with the flow rate flowing into 1. Thereby, the same action and effect as those described in the above-described embodiment can be obtained.

<Additional notes>
The heating system described in each embodiment and the control method thereof are grasped as follows, for example.

(1) The heating system 100 according to the first aspect has a refrigerant circuit in which CO2 as a refrigerant repeatedly condenses and evaporates and circulates, and heats the liquid to be heated introduced from the inlet 1a and discharges it from the outlet 1b. The heat exchange unit 1 and the liquid to be heated circulate and are connected to the inlet 1a and the outlet 1b of the heat exchange unit 1 and cool the liquid to be heated by heat exchange with the liquid to be heated. In the circulation flow path 3 connected to the heating load 2, the return flow path 4 connecting the circulation flow path 3 between the inlet 2a side and the outlet 2b side of the heating load 2, and the circulation flow path 3. A circulation pump 5 provided on the outlet 2b side of the heating load 2 between the return flow path 4 and the heating load 2 and capable of pumping the liquid to be heated and changing the discharge flow rate. A flow rate adjusting unit 6 provided in the circulation flow path 3 for adjusting the flow rate of the liquid to be heated flowing into the heat exchange unit 1, a control device for controlling the circulation pump 5, and the flow rate adjusting unit 6. The control device 90 adjusts the discharge flow rate of the circulation pump 5 based on the difference between the temperature of the liquid to be heated on the inlet 2a side of the heating load 2 and the temperature on the outlet 2b side. At the same time, the first control unit 81 that operates the flow rate adjusting unit 6 so that the flow rate of the liquid to be heated flowing into the heat exchange unit 1 becomes equal to or higher than a predetermined lower limit value regardless of the change in the discharge flow rate. Have.

According to the above configuration, the first control unit 81 of the control device 90 determines the discharge flow rate of the circulation pump 5 based on the difference between the temperature of the liquid to be heated on the inlet 2a side of the heating load 2 and the temperature on the outlet 2b side. adjust. For example, when the temperature difference changes in the direction of decreasing (that is, the amount of heat required by the heating load 2 changes in the direction of decreasing), the first control unit 81 sets the discharge flow rate of the circulation pump 5. Change in the direction of decrease. Further, at this time, the flow rate adjusting unit 6 operates so that the flow rate of the liquid to be heated flowing into the heat exchange unit 1 becomes equal to or higher than a predetermined lower limit value regardless of the change in the discharge flow rate of the circulation pump 5. As a result, the temperature difference between the inlet 2a side and the outlet 2b side of the heating load 2 becomes large, and this can be maintained at a constant value. Further, even when the amount of heat required by the heating load 2 is reduced in this way, a flow rate equal to or higher than the lower limit value is supplied to the heat exchange unit 1. As a result, the heat exchange unit 1 can be operated at the optimum operating point. On the other hand, when the flow rate flowing into the heat exchange unit 1 is also infinitely reduced as the amount of heat required by the heating load 2 is reduced, the liquid to be heated with a small flow rate is heated to a higher temperature state. It will be necessary to continue to do so. This may hinder the efficient operation of the heat exchange unit 1. However, according to the above configuration, such a possibility can be reduced and the heat exchange unit 1 can be operated reasonably and stably.

(2) In the heating system 100 according to the second aspect, the first control unit 81 has a flow rate of the liquid to be heated flowing into the heat exchange unit 1 regardless of a change in the discharge flow rate of the circulation pump 5. The flow rate adjusting unit 6 is operated so as to be equal to or less than a predetermined upper limit value.

According to the above configuration, the first control unit 81 operates the flow rate adjusting unit 6 so that the flow rate of the liquid to be heated flowing into the heat exchange unit 1 is equal to or less than a predetermined upper limit value. Here, in the various pipes and equipment of the heat exchange unit 1, if the flow rate exceeds a certain level, erosion may occur. However, according to the above configuration, since the upper limit value is provided for the flow rate, such a possibility can be reduced.

(3) In the heating system 100 according to the third aspect, the flow rate adjusting unit 6 is provided on the inlet 1a side of the heat exchange unit 1 with respect to the return flow path 4 in the circulation flow path 3, and has an opening degree. It is a valve device V1 that can be continuously changed, and the first control unit 81 changes the opening degree of the valve device V1.

According to the above configuration, the valve device V1 is used as the flow rate adjusting unit 6, and the opening degree of the valve device V1 is changed by the first control unit 81, so that the liquid to be heated flowing into the heat exchange unit 1 can be easily and inexpensively charged. The flow rate can be greater than or equal to a predetermined lower limit.

(4) The heating system 100 according to the fourth aspect is provided on the inlet 1a side of the heat exchange unit 1 with respect to the return flow path 4 in the circulation flow path 3, and is a flow rate for measuring the flow rate of the liquid to be heated. The flow rate adjusting unit 6 further includes a measuring unit 80, and the flow rate adjusting unit 6 is a three-way valve V2 provided at a connection portion between the return flow path 4 and the circulation flow path 3 on the outlet 1b side of the heat exchange unit 1. The first control unit 81 changes the open state of the three-way valve V2 based on the measurement result of the flow rate measurement unit.

According to the above configuration, heat is easily and inexpensively generated by using the three-way valve V2 as the flow rate adjusting unit 6 and changing the open state by the first control unit 81 based on the measurement result of the flow rate measuring unit 80. The flow rate of the liquid to be heated flowing into the exchange unit 1 can be set to be equal to or higher than a predetermined lower limit value.

(5) In the heating system 100 according to the fifth aspect, the control device 90 makes the temperature of the liquid to be heated on the inlet 2a side of the heating load 2 a predetermined inlet target temperature. It further has a second control unit 82 that changes the output of the heat exchange unit 1.

According to the above configuration, the second control unit 82 changes the output of the heat exchange unit 1 so that the temperature of the liquid to be heated at the inlet 2a of the heating load 2 becomes the inlet target temperature. As a result, even when the inlet target temperature changes, the temperature of the liquid to be heated can be immediately followed with high responsiveness.

(6) The method for controlling the heating system according to the sixth aspect has a refrigerant circuit in which CO2 as a refrigerant repeatedly condenses and evaporates and circulates, and heats the liquid to be heated introduced from the inlet 1a to the outlet 1b. The heat exchange unit 1 discharged from the heater and the liquid to be heated circulate and are connected to the inlet 1a and the outlet 1b of the heat exchange unit 1, and the liquid to be heated is exchanged by heat exchange with the liquid to be heated. A circulation flow path 3 connected to the heating load 2 to be cooled, a return flow path 4 connecting the circulation flow path 3 between the inlet 2a side and the outlet 2b side of the heating load 2, and the circulation flow path. A circulation that is provided between the return flow path 4 and the heating load 2 on the outlet 2b side of the heating load 2 in No. 3 and is capable of pumping the liquid to be heated and changing the discharge flow rate. A control method for a heating system 100 including a pump 5 and a flow rate adjusting unit 6 provided in the circulation flow path 3 and adjusting the flow rate of the liquid to be heated flowing into the heat exchange unit 1. A difference calculation step S12 for calculating the difference between the temperature of the liquid to be heated on the inlet 2a side of the load 2 and the temperature on the outlet 2b side, and a pump adjustment step for adjusting the discharge flow rate of the circulation pump 5 based on the difference. A flow rate adjusting step of operating the flow rate adjusting unit 6 so that the flow rate of the liquid to be heated flowing into the heat exchange unit becomes equal to or higher than a predetermined lower limit value regardless of the change in the discharge flow rate of S14A and S14B. Includes S15A and S15B.

According to the above method, first, the difference between the temperature of the liquid to be heated on the inlet 2a side of the heating load 2 and the temperature on the outlet 2b side is obtained by the difference calculation step S12. In the pump adjustment steps S14A and S14B, the discharge flow rate of the circulation pump 5 is adjusted based on this difference. For example, when the temperature difference changes in the direction of decreasing (that is, the amount of heat required by the heating load 2 changes in the direction of decreasing), the discharge flow rate of the circulation pump 5 is changed in the direction of decreasing. .. Further, in the flow rate adjusting steps S15A and S15B, the flow rate adjusting unit 6 makes the flow rate of the liquid to be heated flowing into the heat exchange unit 1 equal to or higher than a predetermined lower limit value regardless of the change in the discharge flow rate of the circulation pump 5. Works like this. As a result, the temperature difference between the inlet 2a side and the outlet 2b side of the heating load 2 becomes large, and this can be maintained at a constant value. Further, even when the amount of heat required by the heating load 2 is reduced in this way, a flow rate equal to or higher than the lower limit value is supplied to the heat exchange unit 1. As a result, the heat exchange unit 1 can be operated at the optimum operating point. On the other hand, when the flow rate flowing into the heat exchange unit 1 is also infinitely reduced as the amount of heat required by the heating load 2 is reduced, the liquid to be heated with a small flow rate is heated to a higher temperature state. It will be necessary to continue to do so. This may hinder the efficient operation of the heat exchange unit 1. However, according to the above method, such a possibility can be reduced and the heat exchange unit 1 can be operated reasonably and stably.

(7) In the control method of the heating system 100 according to the seventh aspect, in the flow rate adjusting steps S15A and S15B, the flow rate of the liquid to be heated flowing into the heat exchange unit 1 is increased regardless of the change in the discharge flow rate. The flow rate adjusting unit 6 is operated so as to be equal to or less than a predetermined upper limit value.

According to the above method, in the flow rate adjusting steps S15A and S15B, the flow rate adjusting unit 6 is operated so that the flow rate of the liquid to be heated flowing into the heat exchange unit 1 is equal to or less than a predetermined upper limit value. Here, in the various pipes and equipment of the heat exchange unit 1, if the flow rate exceeds a certain level, erosion may occur. However, according to the above method, since the upper limit value is provided for the flow rate, such a possibility can be reduced.

100 Heating system 1 Heat exchange unit 1a Inlet 1b Outlet 2 Heating load 2a Inlet 2b Outlet 3 Circulation flow path 4 Return flow path 4a Inlet 4b Outlet 5 Circulation pump 6 Flow control unit 71 First temperature detection unit 72 Second temperature detection unit 73 Third temperature detection unit 80 Flow measurement unit 81 First control unit 82 Second control unit 83 Storage unit 84 Judgment unit 90 Control device 91 CPU
92 ROM
93 RAM
94 HDD
95 Signal transmission / reception module V1 Valve device V2 Three-way valve

Claims (7)

It has a refrigerant circuit in which CO2, which is a refrigerant, circulates by repeating sensible heat change or condensation and evaporation, and also has a heat exchange unit that heats the liquid to be heated introduced from the inlet and discharges it from the outlet.
A circulation flow path in which the liquid to be heated circulates and is connected to an inlet and an outlet of the heat exchange unit and is connected to a heating load that cools the liquid to be heated by heat exchange with the liquid to be heated. When,
A return flow path connecting the circulation flow path between the inlet side and the outlet side of the heating load,
A circulation pump provided on the outlet side of the heating load in the circulation flow path and between the return flow path and the heating load, capable of pumping the liquid to be heated and changing the discharge flow rate. When,
A flow rate adjusting unit provided in the circulation flow path and adjusting the flow rate of the liquid to be heated flowing into the heat exchange unit, and a flow rate adjusting unit.
A control device that controls the circulation pump and the flow rate adjusting unit,
With
The control device is
The discharge flow rate of the circulation pump is adjusted based on the difference between the temperature of the liquid to be heated on the inlet side of the heating load and the temperature on the outlet side, and the heat exchange unit is subjected to regardless of the change in the discharge flow rate. A heating system having a first control unit that operates the flow rate adjusting unit so that the flow rate of the flowing liquid to be heated becomes equal to or higher than a predetermined lower limit value. The first control unit operates the flow rate adjusting unit so that the flow rate of the liquid to be heated flowing into the heat exchange unit is equal to or less than a predetermined upper limit value regardless of the change in the discharge flow rate of the circulation pump. The heating system according to claim 1. The flow rate adjusting unit is a valve device provided on the inlet side of the heat exchange unit with respect to the return flow path in the circulation flow path and capable of continuously changing the opening degree.
The heating system according to claim 1 or 2, wherein the first control unit changes the opening degree of the valve device. Further, a flow rate measuring unit provided on the inlet side of the heat exchange unit with respect to the return flow path in the circulation flow path and measuring the flow rate of the liquid to be heated is provided.
The flow rate adjusting unit is a three-way valve provided at a connection portion between the return flow path and the circulation flow path on the outlet side of the heat exchange unit.
The heating system according to claim 1 or 2, wherein the first control unit changes the open state of the three-way valve based on the measurement result of the flow rate measurement unit. The control device is
Any of claims 1 to 4, further comprising a second control unit that changes the output of the heat exchange unit so that the temperature of the liquid to be heated on the inlet side of the heating load becomes a predetermined inlet target temperature. The heating system according to item 1. It has a refrigerant circuit in which CO2, which is a refrigerant, circulates by repeating sensible heat change or condensation and evaporation, and also has a heat exchange unit that heats the liquid to be heated introduced from the inlet and discharges it from the outlet.
A circulation flow path in which the liquid to be heated circulates and is connected to an inlet and an outlet of the heat exchange unit and is connected to a heating load that cools the liquid to be heated by heat exchange with the liquid to be heated. When,
A return flow path connecting the circulation flow path between the inlet side and the outlet side of the heating load,
A circulation pump provided on the outlet side of the heating load in the circulation flow path and between the return flow path and the heating load, capable of pumping the liquid to be heated and changing the discharge flow rate. When,
A flow rate adjusting unit provided in the circulation flow path and adjusting the flow rate of the liquid to be heated flowing into the heat exchange unit, and a flow rate adjusting unit.
It is a control method of a heating system including
A difference calculation step for calculating the difference between the temperature of the liquid to be heated on the inlet side of the heating load and the temperature on the outlet side, and
A pump adjustment step that adjusts the discharge flow rate of the circulation pump based on the difference, and
A flow rate adjustment step of operating the flow rate adjusting unit so that the flow rate of the liquid to be heated flowing into the heat exchange unit becomes equal to or higher than a predetermined lower limit regardless of the change in the discharge flow rate.
How to control the heating system, including. 6. In the flow rate adjusting step, the flow rate adjusting unit is operated so that the flow rate of the liquid to be heated flowing into the heat exchange unit is equal to or less than a predetermined upper limit value regardless of the change in the discharge flow rate. The control method of the heating system described in 1.

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