JP2007132612A - Cogeneration system, control method thereof, and program - Google Patents

Abstract

To provide a cogeneration system capable of preventing cooling water from being frozen with little fuel consumption without adding a special device.
SOLUTION: A fuel cell, a heat exchanger, a cooling water circulation path through which cooling water of the fuel cell is circulated between a primary side line a of the fuel cell and the heat exchanger, and a fan coil unit. 5 and a heating medium circulation path for heating water circulating between the secondary pipe line 3b of the heat exchanger 3 and a heating auxiliary boiler 4 provided in the middle of the heating medium circulation path. A heating medium bypass passage for bypassing the fan coil unit 5; a heating medium bypass passage on-off valve 9 provided in the heating medium bypass passage; and a predetermined freezing indication A control device that opens the heating medium bypass passage on-off valve 9 and forcibly operates the heating auxiliary boiler 4 when the above condition is satisfied.
[Selection] Figure 1

Description

  The present invention relates to a cogeneration system including a cogeneration unit and a cooling water circuit that recovers exhaust heat of the cogeneration unit, and more particularly to a technique for preventing freezing of the cooling circuit.

  The cogeneration system is a system that includes a cogeneration unit and a cooling water circulation path that recovers the exhaust heat of the cogeneration unit, and uses the exhaust heat of the cogeneration unit for heating and hot water supply. The cooling water circulation path is a system that absorbs the exhaust heat from the combined heat and power supply means and takes out the high temperature cooling water and uses it as a heat source for heating and hot water supply. It is the circulation path which recirculates to the simultaneous supply means.

  Normally, the cogeneration system operates during the day and stops at night. In cold regions in winter, the outside air temperature may drop while the cogeneration system is stopped, and the cooling water may freeze in the cooling water circulation path, damaging piping and the like.

  Therefore, various cogeneration systems including a device for preventing freezing of the cooling water in the cooling water circulation path have been proposed. For example, Patent Document 1 discloses a generator that generates electric power and generated heat, a reformer that supplies hydrogen to the generator, a reformer combustion apparatus that heats the reformer, a generator and a reformer, A power generation unit housing for storing the reformer combustion device, a hot water storage tank, a water circulation path for sending the hot water in the hot water storage tank to the power generation unit housing, heating it with the generator and the reformer combustion device, and returning it to the hot water storage tank; A cogeneration system having a control device that forcibly operates the combustion apparatus for reformer when the temperature is lower than a predetermined temperature during power generation is disclosed.

  Further, Patent Document 1 discloses a generator that generates electric power and generated heat, a hot water storage tank, a water circulation path that sends hot water in the hot water tank to the generator, heats it with the generated heat, and returns the hot water to the hot water tank, and the hot water tank. A temperature control combustion device that heats the hot water to a set temperature and supplies the hot water to a hot water use location, a water supply pipe that supplies water to the hot water tank, and a heat storage unit housing that houses at least the water supply tube and the temperature control combustion device; A cogeneration system having a control device for forcibly operating the temperature control combustion device when the temperature is not higher than a predetermined temperature during non-power generation is disclosed.

  Patent Document 2 discloses a generator that generates electric power and generated heat, a hot water storage tank, a water circulation path that sends water in the hot water storage tank to the generator, heats the generated heat to return to the hot water tank, and a hot water storage tank. A first water supply channel for replenishing water, a second water supply channel for supplying water mixed in the hot water discharge pipe from the hot water storage tank, and a first water supply channel and a second water supply channel that pass through the hot water storage tank to transfer heat. An anti-freezing path including a path to perform, a pump for circulating hot water in the anti-freezing path, and a pump control device that drives the pump when the outside air temperature is equal to or lower than the first predetermined temperature or the feed water temperature is equal to or lower than the second predetermined temperature. A cogeneration system is disclosed.

  Patent Document 3 discloses a power generation unit, a heating means for heating to hot water using the exhaust heat of the power generation unit, a hot water storage tank for storing hot water heated by the heating means, and hot water in the hot water storage tank at a set temperature. A hot water supply means for adjusting the temperature of the hot water and supplying the hot water to the location where the hot water is used, and being provided between the heating means and the hot water tank and sending the hot water in the hot water tank to the heating means and returning it to the hot water tank. A circulation path, a pump that circulates hot water in the first circulation path, and a pump control device that forcibly drives the pump when the power generation unit is stopped and the outside air temperature is equal to or lower than a first predetermined temperature. A cogeneration system is disclosed.

  Further, in Patent Document 3, when the power generation unit is stopped, the outside air temperature is lower than the first predetermined temperature, and the water temperature in the first circulation path is lower than the third predetermined temperature, the power generation unit It is also disclosed to add a power generation unit control means for forcibly driving a heater built in the.

JP 2004-108173 A JP 2004-60980 A JP 2003-254621 A

  However, the cogeneration system described in Patent Document 1 heats the equipment in the housing by discharging the combustion gas of the reformer combustion device or the temperature control combustion device into the power generation unit housing or the heat storage unit housing. Therefore, a heat generation amount corresponding to the heat capacity of all the devices in the housing (these devices include devices that do not need to be frozen) is required. That is, there is a problem that fuel consumption is large. In addition, since the piping connecting the power generation unit and the heat storage unit (this piping is directly exposed to the outside air, the risk of freezing) is lacking, so the water in the piping is effectively frozen. There is also a problem that cannot be prevented.

  In addition, the cogeneration system described in Patent Document 2 requires a dedicated anti-freezing route that includes a heat transfer route that is parallel to the first water supply channel and the second water supply channel, resulting in a complicated structure and an increase in cost. There is a problem of inviting.

  Moreover, since the cogeneration system of patent document 3 uses the warm water in a hot water tank for the freeze prevention of a circulation path, there exists a problem that the temperature of the warm water in a hot water tank falls.

  The present invention has been made to solve such problems, and provides a cogeneration system that can prevent freezing of the cooling water circulation path without adding a special device and with little fuel consumption. Objective.

  A first configuration of the cogeneration system according to the present invention is a cogeneration unit that generates electric power and heat, a cooling water of the cogeneration unit, and a heating medium (hereinafter referred to as “heating medium”). A heat exchanger for exchanging heat between them, a cooling water circulation path through which cooling water circulates between the cogeneration means and the primary side pipe of the heat exchanger, a secondary of the heater and the heat exchanger A cogeneration system comprising a heating heat medium circulation path through which a heating heat medium circulates between the side pipes and an auxiliary heat source device that is provided in the middle of the heating heat medium circulation path to heat the heating heat medium. In the system, a heating medium bypass path connected to the heating medium circulation path so as to bypass the heater; a heating medium bypass path opening / closing valve provided in the heating medium bypass path; and The possibility of freezing while the combined heat and power means is stopped. If you predetermined condition is satisfied, as well as opening the heating heat medium bypass opening and closing valve, controller for forcibly controlled to operate the auxiliary heat source unit; characterized in that it comprises a.

  According to this configuration, when the cogeneration means is stopped, the auxiliary heat source device is operated, the heating heat medium is heated, the heat of the heating heat medium is transferred to the cooling water, and the cooling water circulation path The cooling water inside can be prevented from freezing. Moreover, since the heating medium bypass passage for bypassing the heater is provided, the heat generated by the auxiliary heat source device can be transmitted to the cooling water without being released by the heater. Therefore, fuel consumption for preventing freezing can be reduced. Here, the combined heat and power means is a broad concept including not only a generator powered by a heat engine or the like but also an electrochemical power generation means such as a fuel cell. When generating electric power, all the devices that discharge heat as a by-product are included in the cogeneration means here.

  The means for circulating the cooling water in the cooling water circulation path and the means for circulating the heating heat medium in the heating heat medium circulation path are not particularly limited. In general, forced circulation is performed by providing a pump at an appropriate position in the circulation path, but natural circulation may be performed by using convection.

  A second configuration of the cogeneration system according to the present invention includes a hot water storage tank provided in a section from the heat exchanger of the cooling water circulation path toward the heat and power supply unit in the first configuration, and the hot water storage tank. A hot water tank bypass path connected to the cooling water circulation path so as to be bypassed, and a hot water tank bypass path opening / closing valve provided in the hot water tank bypass path, and the controller is configured to stop the combined heat and power means. When the predetermined condition is satisfied, the hot water tank bypass passage opening / closing valve is opened when the predetermined condition indicating the possibility of freezing is satisfied.

  Cooling water at the minimum temperature required to prevent freezing of the cooling water circulation path circulates in the cooling water circulation path. According to this configuration, since the hot water tank bypass path for bypassing the hot water tank is provided, low temperature cooling water is Does not flow into hot water tank. Therefore, the fall of the temperature of the cooling water stored in a hot water tank can be prevented.

  A third configuration of the cogeneration system according to the present invention includes a temperature sensor that detects a temperature of the cooling water in the first or second configuration, and the predetermined condition is that a temperature detected by the temperature sensor is It is characterized by being below a predetermined threshold value.

  According to this configuration, since the condition for forced operation of the auxiliary heat source device is that the temperature of the cooling water falls below a predetermined temperature, the auxiliary heat source device is forcibly operated only when the possibility of freezing is high. Therefore, the fuel consumption can be further reduced.

  A fourth configuration of the cogeneration system according to the present invention includes a temperature sensor that detects a temperature of an installation environment of the cogeneration system in either the first or second configuration, and the predetermined condition is The temperature detected by the temperature sensor is lower than a predetermined threshold value.

  According to this configuration, since the temperature of the cogeneration system installation environment is lower than a predetermined temperature is a condition for forced operation of the auxiliary heat source unit, the auxiliary heat source unit is forcibly operated only when the possibility of freezing is high. . Therefore, the fuel consumption can be further reduced. In addition, the temperature of the temperature of an installation environment here means the temperature of the atmosphere of the place where the cogeneration system is installed. That is, when the cogeneration system is installed outdoors, it indicates the outside temperature, and when it is installed in the building, it indicates the room temperature of the building.

  A first configuration of the control method of the cogeneration system according to the present invention includes a combined heat and power supply unit that generates electric power and heat, a cooling water of the combined heat and power supply unit, and a heating medium (hereinafter referred to as “heating medium for heating”). )), A cooling water circulation path through which cooling water circulates between the combined heat and power means and the primary pipe of the heat exchanger, and circulation of the cooling water to the cooling water A cooling water pump forcibly circulating in the passage, a heating heat medium circulation path in which a heating heat medium circulates between a heater and a secondary side pipe of the heat exchanger, and the heating heat medium A heating medium pump for forced circulation in the heating medium circulation path, an auxiliary heat source device for heating the heating medium provided in the heating medium circulation path, and bypassing the heater A heating medium bypass passage connected to the heating medium circulation passage, and the heating medium bypass passage. In a control method of a cogeneration system including a heating medium bypass passage opening / closing valve for heating provided in a heating medium bypass passage, when a predetermined condition indicating the possibility of freezing is satisfied while the cogeneration means is stopped A step of opening the heating medium bypass passage opening / closing valve for heating, a step of starting the heating medium pump for heating, a step of starting the auxiliary heat source device, and a step of starting the cooling water pump. It is characterized by that.

The second configuration of the control method of the cogeneration system according to the present invention includes a cogeneration unit that generates electric power and heat, a cooling water of the cogeneration unit, and a heating medium (hereinafter referred to as “heating medium”). )), A cooling water circulation path through which cooling water circulates between the combined heat and power means and the primary pipe of the heat exchanger, and circulation of the cooling water to the cooling water A cooling water pump forcibly circulating in the passage, a hot water storage tank provided in a section from the heat exchanger of the cooling water circulation path to the heat and power supply means, and connected to the cooling water circulation path so as to bypass the hot water storage tank Heating heat medium circulates between the heated hot water tank bypass path, the hot water tank bypass path opening / closing valve provided in the hot water tank bypass path, and the secondary side pipe line of the heater and the heat exchanger The heating medium circulation path and the heating heating medium are A heating medium pump forcibly circulating in the heating medium circulation path, an auxiliary heat source device that is provided in the middle of the heating medium circulation path to heat the heating medium, and bypasses the heater In a control method of a cogeneration system comprising: a heating medium bypass passage connected to the heating medium circulation passage; and a heating medium bypass passage opening / closing valve provided in the heating medium bypass passage; A step of opening the heating medium bypass passage on-off valve for heating and a step of opening the hot water tank bypass passage on-off valve when a predetermined condition indicating the possibility of freezing is satisfied while the cogeneration means is stopped; The step of activating the heating medium pump for heating, the step of activating the auxiliary heat source device, and the step of activating the cooling water pump are provided.

  According to a third configuration of the control method of the cogeneration system according to the present invention, in the first or second configuration, the cogeneration system includes a temperature sensor that detects a temperature of the cooling water, and the predetermined condition is set. Is characterized in that the temperature detected by the temperature sensor is below a predetermined threshold.

  According to a fourth configuration of the control method of the cogeneration system according to the present invention, in the first or second configuration, the cogeneration system includes a temperature sensor that detects a temperature of an installation environment, and the predetermined condition is The temperature detected by the temperature sensor is lower than a predetermined threshold value.

  The program according to the present invention causes a computer to execute the control method of the cogeneration system according to the first to fourth configurations.

  As described above, according to the present invention, freezing of cooling water can be prevented with a small amount of fuel without adding a new heating device or the like to the cogeneration system.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a piping diagram of a cogeneration system 1 according to an embodiment of the present invention. The cogeneration system 1 includes a fuel cell 2, a heat exchanger 3, a heating auxiliary boiler 4, a fan coil unit 5, a hot water tank 6, a radiator 7, and other devices described later. The cogeneration system 1 is controlled by a control computer (not shown). Further, the water supply system and the hot water system piping of the cogeneration system 1 are not directly related to the present invention, and are not shown in the figure.

  The fuel cell 2 is a combined heat and power supply means for supplying power to a power load (not shown), and includes a cooling pipe (not shown) that absorbs and discharges exhaust heat (generated heat) generated as a by-product of the power into the cooling water. Yes. Further, the cooling water that has become high temperature by absorbing the exhaust heat flows out from the cooling pipe and flows into the primary side pipe 3 a of the heat exchanger 3.

  The heat exchanger 3 includes cooling water that flows out from the fuel cell 2 and flows into the primary side conduit 3a, and heating water that flows out from the fan coil unit 5 and flows into the secondary side conduit 3b (heating medium for heating). It is an apparatus which heats the heating water by exchanging heat between them.

  The auxiliary heating boiler 4 is operated when the temperature of the heating water flowing out from the secondary side pipe 3b of the heat exchanger 3 is lower than the required temperature of the fan coil unit 5, and heats the heating water. It is.

  The fan coil unit 5 is a heater that discharges heat of high-temperature heating water flowing through the secondary side pipe 3b of the heat exchanger 3 and the auxiliary boiler 4 for heating into the space to be heated. In addition, 8 is a circulation pump which circulates the said heating water in the heating water circulation path which returns from the secondary side pipe line 3b of the heat exchanger 3 to the secondary side pipe line 3b through the heating auxiliary boiler 4 and the fan coil unit 5. is there. Reference numeral 9 denotes a heating medium bypass passage opening / closing valve for opening and closing a pipe passage (heating heating medium bypass passage) that bypasses the fan coil unit 5.

  The hot water tank 6 is a container for storing cooling water. The cooling water flowing out of the fuel cell 2 during operation of the fuel cell 2 is sufficiently hot even if heat is exchanged in the heat exchanger 3, so that it is injected from the top of the hot water tank 6, and if necessary, a hot water supply load (not shown) (For example, currants, shower heads, etc.) and a heat load (for example, a heat exchanger for reheating a bathtub). In addition, since the cooling water that has lost its heat and stayed at a low temperature is retained at the bottom of the hot water tank 6, it is extracted and returned to the fuel cell 2.

  The radiator 7 is a radiator that cools the cooling water to a predetermined temperature when the temperature of the cooling water returning to the fuel cell 2 exceeds a predetermined temperature (when the cooling water is not sufficiently cooled).

  Hereinafter, in the present specification, the cooling water that has become high temperature by absorbing the generated heat generated in the fuel cell 2 is taken out, and the cooling water is used as a heat source for heating and hot water supply, and the generated heat is released. A circuit that circulates the cooling water having a low temperature to the fuel cell 2 will be referred to as a “cooling water circuit”. In addition, a cooling water circulation pump (not shown) is provided inside the fuel cell 2, and the cooling water that has become high temperature by absorbing generated heat is sent to the cooling water circulation path.

  10 is a three-way valve. The three-way valve 10 is a switching valve that selects a flow path 10 a from the primary side pipe 3 a of the heat exchanger 3 to the hot water storage tank 6 and a flow path 10 b from the heat exchanger bypass flow path 11 to the hot water storage tank 6. When the fan coil unit 5 is in operation, the flow path 10 a is selected, and high-temperature cooling water flowing out from the fuel cell 2 is passed through the heat exchanger 3 to supply heat to the fan coil unit 5. When the fan coil unit 5 is stopped, the flow path 10b is selected, and the high-temperature cooling water flowing out from the fuel cell 2 bypasses the heat exchanger 3 and flows directly into the hot water tank 6.

  12 is a hot water tank bypass valve, and 13 is a circulation path opening / closing valve. When the temperature of the cooling water passing through the three-way valve 10 is lower than a predetermined temperature (for example, 40 ° C.) (for example, immediately after the operation of the fuel cell 2 is started), the hot water tank bypass valve 12 is opened and the circulation path opening / closing valve 13 is opened. Close and allow cooling water to flow directly to the radiator 7. Conversely, when the temperature of the cooling water passing through the three-way valve 10 is higher than a predetermined temperature (for example, 45 ° C.), the hot water tank bypass valve 12 is closed, the circulation path on / off valve 13 is opened, and the cooling water is supplied to the hot water tank 6. While pouring, the cooling water in the lower layer of the hot water tank 6 is caused to flow to the radiator 7. This is because hot water of a certain temperature or higher is stored in the hot water tank 6.

  In addition, since the fuel cell 2 requires time to start the reformer, there is a technical request that it is not desired to frequently start and stop the reformer. Therefore, the radiator 7 is provided so that the fuel cell 2 can be sufficiently cooled even when the heat consumption is low. Therefore, the radiator 7 is not required when using a combined heat and power supply means such as an engine generator that is easy to start and stop instead of the fuel cell 2.

  Reference numeral 14 denotes a cooling water temperature detector that detects the temperature of the cooling water flowing from the fuel cell 2.

  FIG. 2 is a flowchart showing a control method for preventing the cooling water from freezing while the operation of the fuel cell 2 is stopped in the cogeneration system 1. Hereinafter, a method for preventing freezing of cooling water will be described with reference to step numbers given in the flowchart. The control flow shown in FIG. 2 is programmed and installed in the control computer of the cogeneration system 1, and is executed by the control computer instructing the components of the cogeneration system 1.

(Step 1) If the cooling water temperature T detected by the cooling water temperature detector 14 is less than 3 ° C, the process proceeds to Step 2, and if it is 3 ° C or more, the process returns to the top of Step 1.

(Step 2) The heating medium bypass passage opening / closing valve 9 for heating is opened.

(Step 3) The three-way valve 10 is operated to select the flow path 10a, the hot water tank bypass valve 12 is opened, and the circulation path open / close valve 13 is closed. As a result, the cooling water flowing out from the fuel cell 2 passes through the heat exchanger 3 and recirculates to the fuel cell 2 bypassing the hot water tank 6.

(Step 4) The circulation pump 8 is started. Since the heating medium bypass passage opening / closing valve 9 is opened in step 2, when the circulation pump 8 is activated, the heating water from the auxiliary heating boiler 4 to the fan coil unit 5 bypasses the fan coil unit 5 and performs heat exchange. Reflux to vessel 3.

  Normally, the flow resistance in the fan coil unit 5 is larger than the flow resistance in the bypass passage. Therefore, most of the heating water can be heated only by opening the heating medium bypass passage opening / closing valve 9. When the flow path resistance inside the fan coil unit 5 is not large, the flow opens and closes to the heating water flow path from the heating auxiliary boiler 4 to the fan coil unit 5. It is necessary to provide a valve.

(Step 5) The auxiliary boiler 4 for heating is ignited. Thereby, the high-temperature heating water heated by the heating auxiliary boiler 4 flows into the secondary side pipe line 3b of the heat exchanger 3.

(Step 6) The cooling water circulation pump of the fuel cell 2 is started. Thereby, the cooling water flows out from the fuel cell 2 and flows into the primary side pipe 3a of the heat exchanger 3, and is heated by the high-temperature heating water flowing through the secondary side pipe 3b.

(Step 7)
If the cooling water temperature T detected by the cooling water temperature detector 14 exceeds 6 ° C., the operation is stopped, and if it is lower than 6 ° C., the process returns to the top of step 7.

  Thus, when the cooling water temperature T is less than 3 ° C, the heating auxiliary boiler 4 is ignited to heat the cooling water, and when the cooling water temperature T exceeds 6 ° C, the heating is stopped. The temperature of the water is kept between 3 ° C. and 6 ° C. to prevent the cooling water from freezing.

  In the present embodiment, the level of the cooling water temperature T detected by the cooling water temperature detector 14 is set as the heating start / stop condition. However, a detector that detects the temperature of the atmosphere at the location where the cogeneration system 1 is installed is used. In addition, the temperature of the atmosphere may be set as the heating start / stop condition. Alternatively, a temperature detector may be provided in the middle of the cooling pipe of the fuel cell 2 and the temperature of the cooling water in the cooling pipe may be set as the heating start / stop condition.

It is a piping system diagram of a cogeneration system concerning an example of the present invention. It is a flowchart which shows the control method which concerns on the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cogeneration system 2 Fuel cell 3 Heat exchanger 4 Heating auxiliary boiler 5 Fan coil unit 6 Hot water tank 7 Radiator 8 Circulation pump
9 Heating medium bypass passage opening / closing valve for heating 10 Three-way valve 11 Heat exchange bypass passage 12 Hot water tank bypass valve 13 Circulation passage opening / closing valve 14 Cooling water temperature detector

Claims (9)

A cogeneration means for generating electric power and heat;
A heat exchanger that exchanges heat between the cooling water of the cogeneration means and a heating medium (hereinafter referred to as “heating medium”);
A cooling water circulation path through which cooling water circulates between the cogeneration means and the primary pipe of the heat exchanger;
A heating medium circulation path for heating in which a heating medium circulates between the heater and the secondary side pipe of the heat exchanger;
In a cogeneration system having an auxiliary heat source device that is provided in the middle of the heating medium circulation path and heats the heating medium,
A heating medium bypass passage connected to the heating medium circulation passage so as to bypass the heater;
A heating medium bypass passage opening / closing valve provided in the heating medium bypass passage;
And, when a predetermined condition indicating the possibility of freezing is satisfied while the cogeneration means is stopped, the heating medium bypass passage opening / closing valve for heating is opened and the auxiliary heat source device is forcibly operated. A control device for performing control;
Cogeneration system characterized by comprising. A hot water storage tank provided in a section from the heat exchanger of the cooling water circulation path toward the combined heat and power means;
A hot water tank bypass path connected to the cooling water circulation path so as to bypass the hot water tank;
A hot water tank bypass passage opening and closing valve provided in the hot water tank bypass passage,
2. The cogeneration system according to claim 1, wherein the control device opens the hot water tank bypass passage opening / closing valve when the predetermined condition is satisfied while the cogeneration unit is stopped. 3. . A temperature sensor for detecting the temperature of the cooling water;
The cogeneration system according to claim 1 or 2, wherein the predetermined condition is that a temperature detected by the temperature sensor falls below a predetermined threshold. A temperature sensor for detecting the temperature of the installation environment of the cogeneration system is provided,
The cogeneration system according to claim 1 or 2, wherein the predetermined condition is that a temperature detected by the temperature sensor falls below a predetermined threshold. A cogeneration means for generating electric power and heat;
A heat exchanger that exchanges heat between the cooling water of the cogeneration means and a heating medium (hereinafter referred to as “heating medium”);
A cooling water circulation path through which cooling water circulates between the cogeneration means and the primary pipe of the heat exchanger;
A cooling water pump for forcibly circulating the cooling water in the cooling water circuit;
A heating medium circulation path for heating in which a heating medium circulates between the heater and the secondary side pipe of the heat exchanger;
A heating medium pump for forcibly circulating the heating medium in the heating medium circulation path;
An auxiliary heat source device that is provided in the middle of the heating medium circulation path and that heats the heating medium, and a heating medium bypass path that is connected to the heating medium circulation path so as to bypass the heater ,
In a control method of a cogeneration system comprising a heating medium bypass passage on-off valve for heating provided in the heating medium bypass passage,
A step of opening the heating medium bypass passage on-off valve for heating and a step of starting the heating medium pump for heating when a predetermined condition indicating the possibility of freezing is satisfied while the cogeneration means is stopped;
Activating the auxiliary heat source device;
Activating the cooling water pump;
A control method for a cogeneration system, comprising: A cogeneration means for generating electric power and heat;
A heat exchanger that exchanges heat between the cooling water of the cogeneration means and a heating medium (hereinafter referred to as “heating medium”);
A cooling water circulation path through which cooling water circulates between the cogeneration means and the primary pipe of the heat exchanger;
A cooling water pump for forcibly circulating the cooling water in the cooling water circuit;
A hot water storage tank provided in a section from the heat exchanger of the cooling water circulation path toward the combined heat and power means;
A hot water tank bypass path connected to the cooling water circulation path so as to bypass the hot water tank;
A heating-medium circulation path in which a heating-heat medium circulates between a hot-water tank bypass path opening / closing valve provided in the hot-water tank bypass path, a heater, and a secondary side pipe of the heat exchanger;
A heating medium pump for forcibly circulating the heating medium in the heating medium circulation path;
An auxiliary heat source device that is provided in the middle of the heating medium circulation path and that heats the heating medium, and a heating medium bypass path that is connected to the heating medium circulation path so as to bypass the heater ,
In a control method of a cogeneration system comprising a heating medium bypass passage on-off valve for heating provided in the heating medium bypass passage,
A step of opening the heating medium bypass passage on-off valve for heating and a step of opening the hot water tank bypass passage on-off valve when a predetermined condition indicating the possibility of freezing is satisfied while the cogeneration means is stopped When,
Activating the heating medium pump for heating;
Activating the auxiliary heat source device;
And a step of activating the cooling water pump. The cogeneration system includes a temperature sensor that detects a temperature of the cooling water,
The cogeneration system control method according to claim 5 or 6, wherein the predetermined condition is that a temperature detected by the temperature sensor is lower than a predetermined threshold value. The cogeneration system includes a temperature sensor that detects the temperature of the installation environment,
The cogeneration system control method according to claim 5 or 6, wherein the predetermined condition is that a temperature detected by the temperature sensor falls below a predetermined threshold. A program for causing a computer to execute the control method of the cogeneration system according to any one of claims 5 to 8.

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