JP5625683B2 - Control device for hot water system - Google Patents

Description

  The present invention stores hot water as heat storage by recovering exhaust heat from cooling water from a gas engine or a fuel cell, heat from a heat pump refrigerant, or exhaust heat from an external heat source such as solar energy from natural energy. More particularly, the present invention relates to a control device for storing heat as hot water storage at a predetermined temperature by exhaust heat recovery.

2. Description of the Related Art Conventionally, a control device for a hot water system is known that circulates a refrigerant of an engine heat pump air conditioner and stores hot water heated by heat recovery from the refrigerant in a hot water storage tank (see, for example, Patent Document 1). In Patent Document 1, a hot water supply path for extracting hot water from the top of a hot water tank and a circulation path that is taken out from one end of the bottom of the hot water tank and returned to the other end of the same bottom are piped. Is provided with a heating means comprising a heat recovery unit from the refrigerant and an auxiliary heat source unit, and further, branched from a downstream position of the heating means and joined to the hot water supply path to share the hot water supply path. The hot water inside can be returned to the hot water storage tank or mixed with hot water for hot water supply in the hot water supply passage.
The present applicant has proposed a structure of a hot water system in Japanese Patent Application No. 2009-109744 as a hot water system for storing heat as hot water storage by recovering exhaust heat from the external heat source as described above.

JP 2003-28504 A

  By the way, when recovering exhaust heat from an external heat source such as gas engine cooling water and storing it as hot water storage, liquid-liquid heat exchange is performed between the cold hot water extracted from the hot water storage tank and the cooling water of the gas engine. When the exhaust heat hot water storage operation is performed by circulating operation in which the hot water heated by heat exchange from the cooling water or the like is returned to the hot water storage tank and stored, the exhaust heat is not affected regardless of the level of the exhaust heat. There is a demand to raise the temperature of the hot water in the hot water tank to the target temperature as much as possible by heat exchange heating.

  However, the exhaust heat of the external heat source changes depending on the operation status of the external heat source and is not constant. Therefore, it is difficult to control the hot water storage to the target temperature by exhaust heat recovery in the exhaust heat hot water storage operation. Become. Here, if the exhaust heat recovery is such that the hot water in the hot water tank is merely preheated, the target temperature may be set to a relatively low temperature, and therefore the exhaust heat hot water storage operation can be easily realized. However, in the original hot water system, if the hot water storage can be used as it is for the hot water supply as it is, it will not be necessary to use auxiliary heating with energy consumption. Has a circumstance that it is desired to set the temperature as high as possible (for example, 75 ° C. or higher). For this reason, it is difficult to store hot water at the target temperature by exhaust heat recovery from an external heat source.

  The present invention has been made in view of such circumstances, and an object of the present invention is a hot water system capable of easily reaching a target hot water temperature in an exhaust heat hot water storage operation by exhaust heat recovery from an external heat source. It is to provide a control device.

In order to achieve the above object, in the present invention, a hot water storage tank for storing heat as hot water storage by recovering exhaust heat from an external heat source, and hot water taken out from the bottom of the hot water storage tank are circulated back to the top of the hot water storage tank. A circulation circuit for causing the hot water to circulate, and a waste heat recovery section for heating the circulating hot water by recovering the exhaust heat from the external heat source. On the other hand, an external heat load circuit and a take-out path are branched from a circulation circuit located downstream of the exhaust heat recovery section, and the downstream end of the external heat load circuit is connected to bypass the hot water tank. Connected to a circulation circuit from the bottom of the hot water tank, the take-out path is connected to a circulation circuit at the upstream side of the circulation pump via a mixing means at the downstream end thereof. In the elephant was that comprises the following specific matters. That is, the waste heat storage hot water which operates the circulation pump, circulates the hot water in the hot water storage tank to the circulation circuit, raises the temperature to the target hot water storage temperature by exhaust heat recovery in the exhaust heat recovery section, and stores the hot water in the hot water storage tank. Operation control means and temperature detection means for detecting the temperature of the circulating hot water after exhaust heat recovery on the outlet side of the exhaust heat recovery unit are provided. And, the exhaust heat hot water storage operation control means, as a control part for executing countermeasure control according to the detected temperature of the circulating hot water by the temperature detection means, a circulation pump adjustment control part for changing and adjusting the discharge flow rate of the circulation pump And a mixing amount adjustment control unit for increasing and changing the mixing flow rate on the take-out path side in the mixing means, and external heat for opening the on-off valve provided in the external heat load circuit and diverting the circulating hot water from the circulation circuit It shall be the structure and a load circuit opening control unit.

In the case of this technical matter , the circulation flow rate to the waste heat recovery part of the low-temperature hot water taken out from the bottom of the hot water tank is reduced by restricting the discharge flow rate of the circulation pump by the circulation pump adjustment control part. Even if the heating capacity for exhaust heat is poor, it is possible to increase the temperature rise of the circulating hot water, and it is possible to easily raise the temperature to the target hot water storage temperature. Moreover, the ratio of the low-temperature hot water taken out from the bottom of the hot water tank in the hot water circulated to the exhaust heat recovery unit is reduced by increasing and changing the mixing flow rate on the take-out path side in the mixing means by the mixing amount adjustment control unit. Therefore, even if the exhaust heat heating capability in the exhaust heat recovery unit is insufficient, the temperature rise of the circulating hot water can be further increased, and the temperature can be more easily raised to the target hot water storage temperature. Furthermore, by opening the on-off valve provided in the external heat load circuit by the external heat load circuit opening control unit, the circulating hot water exiting the exhaust heat recovery unit is diverted from the circulation circuit to the external heat load circuit, and the hot water tank is Since it is bypassed and returned to the circulation circuit, the amount of low-temperature hot water taken out from the bottom of the hot water tank can be reduced accordingly. As a result, even if the exhaust heat heating capacity in the exhaust heat recovery section is poor, the temperature rise of the circulating hot water can be further increased, and the temperature can be raised more easily to the target hot water storage temperature. As described above, the hot water storage temperature can be easily reached to the target temperature in the exhaust heat hot water storage operation.

In addition, in the present invention, the mixing amount adjustment control unit is configured to be executed when the circulating hot water does not reach the target hot water storage temperature even if the circulation pump adjustment control unit is changed and adjusted to reduce the discharge flow rate. In addition, the external heat load circuit opening control unit is configured to be executed when the circulating hot water does not reach the target hot water storage temperature even when the mixing amount adjustment control unit increases and changes the mixing flow rate on the extraction path side . (Claim 1 ). In this way, it is possible to execute the countermeasure control for raising the temperature of the circulating hot water to the target hot water temperature in a stepwise manner according to the temperature detected by the temperature detecting means. It is possible to easily and reliably raise the circulating hot water to the hot water storage target temperature.

  As described above, according to the control device of the hot water system of the present invention, the exhaust heat recovery unit for low-temperature hot water taken out from the bottom of the hot water tank by restricting the discharge flow rate of the circulation pump by the circulation pump adjustment control unit. The circulation flow rate can be reduced, and even if the exhaust heat heating capacity in the exhaust heat recovery section is poor, the temperature rise of the circulating hot water can be easily increased, and the temperature can be easily raised to the target hot water storage temperature. It becomes like this. In addition, even if the discharge flow rate is changed so as to be reduced, if the temperature does not rise to the target hot water storage temperature, the mixing amount adjustment control unit further increases and changes the mixing flow rate on the take-out path side in the mixing means, thereby reducing waste heat. The ratio of the low-temperature hot water taken out from the bottom of the hot water tank in the hot water circulated to the recovery section can be reduced, which can further increase the temperature rise of the circulating hot water and make it easier to reach the target hot water temperature. It becomes possible to raise the temperature. Furthermore, the external hot load circuit opening control unit opens the on-off valve provided in the external heat load circuit, thereby diverting the circulating hot water exiting the exhaust heat recovery unit from the circulation circuit to the external thermal load circuit, and the hot water storage tank. It can be bypassed and returned to the circulation circuit, and the amount of low-temperature hot water taken out from the bottom of the hot water tank can be reduced accordingly. As a result, even if the exhaust heat heating capacity in the exhaust heat recovery section is poor, the temperature rise of the circulating hot water can be further increased, and the temperature can be raised more easily to the target hot water storage temperature. As described above, the hot water storage temperature can be easily reached to the target temperature in the exhaust heat hot water storage operation.

In addition, as the mixing amount adjustment control unit, the circulation pump adjustment control unit is configured to be executed when the circulating hot water does not reach the target hot water storage temperature even when the circulating flow adjustment control unit is adjusted to reduce the discharge flow rate, and an external heat load circuit The open control unit is configured to be executed when the circulating hot water does not reach the target hot water temperature even when the mixing flow adjustment control unit increases the mixing flow rate on the take-out path side. Therefore, the circulating hot water is raised to the target hot water temperature. The countermeasure control for heating can be executed step by step according to the temperature detected by the temperature detection means, which makes it possible to easily and reliably raise the circulating hot water to the hot water storage target temperature by efficiently using the amount of heat of the exhaust heat. To be able to.

It is a schematic diagram which shows embodiment of this invention. It is a block diagram which shows each control part in an exhaust heat hot water storage operation control means. FIG. 2 is a view corresponding to FIG. 1 for explaining an operation by a circulation pump adjustment control unit. FIG. 2 is a diagram corresponding to FIG. 1 for explaining an operation by a mixing valve adjustment control unit. FIG. 2 is a diagram corresponding to FIG. 1 for explaining an operation by a heating circuit opening control unit. FIG. 2 is a diagram corresponding to FIG. 1 for explaining an operation based on final adjustment by a mixing valve adjustment control unit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of a hot water system to which a control device according to an embodiment of the present invention is applied. In the figure, reference numeral 1 indicates a gas engine as an external heat source, and 2 indicates that the exhaust heat of the gas engine engine coolant is recovered and stored as hot water while hot water in the hot water tank 3 is taken out from the bottom and returned to the top. 4 is a water supply circuit for supplying tap water from the outside, 5 is a hot water supply circuit for supplying hot water to the hot water tap 50 using hot water from the hot water storage tank 3 or hot water after auxiliary heating from the auxiliary heat source unit 6, 7 Is a heating circuit as an external heat load using hot water from the circulation circuit 2 as a heating heat source, and 9 is a bath reheating circuit as another external heat load using the hot water from the circulation circuit 2 as a heat source. It is a controller that controls the operation of this hot water system.

  The gas engine 1 is connected to a heat medium circulation path 11 that circulates between the engine coolant in the interior and the liquid-liquid heat exchanger 21 as a heat source heat medium. The expansion tank 13 is interposed.

  The hot water storage tank 3 is configured in a sealed manner, and a hot water storage temperature sensor 31 for detecting the temperature of the hot water storage is provided at an appropriate place (at least at the top position). Then, the circulation circuit 2 takes out the hot water from the bottom 32 of the hot water tank 3 by the operation of the circulation pump 22 with variable discharge flow rate, passes it through the liquid-liquid heat exchanger 21 as the exhaust heat recovery unit, and further supplies the auxiliary heat source. It is arranged so as to pass through the machine 6 or the auxiliary heat source machine bypass 61 and return to the top 33 of the hot water tank 3. After exiting the auxiliary heat source unit 6 or the auxiliary heat source unit bypass path 61, it reaches the top 33 of the hot water tank 3 through the flow rate adjusting valve 23 with a closing function. Further, a branch point 24 and a branch point 25 described later are disposed between the auxiliary heat source unit 6 and the flow rate adjustment valve 23, and a branch point 26 is disposed at a downstream position of the flow rate adjustment valve 23. Hereinafter, a part of the circulation circuit 2 from the branch point 26 to the top portion 33 of the hot water tank 3 will be referred to as a top side circuit portion 27.

  Furthermore, the downstream end of the extraction path 51 for extracting hot water from the top 33 of the hot water tank 3 is connected to the circulation circuit 2 at the upstream side position of the circulation pump 22 via a first mixing valve 52 as mixing means. . That is, the hot water taken out from the bottom of the hot water tank 3 by the circulation circuit 2 and the hot water circulated as it is from the top side circuit part 27 through the junction 28 by the take-out path 51 in the first mixing valve 52 at a predetermined mixing ratio (0 ˜100%: 100 to 0%), and then, it can be flowed to the liquid-liquid heat exchanger 21 side which is the downstream side. Reference numeral 62 in FIG. 1 denotes a hot water temperature (outlet temperature) in the circulation circuit 2 immediately after exiting from the outlet of the liquid-liquid heat exchanger 21, that is, heat exchange heating by exhaust heat in the liquid-liquid heat exchanger 21. It is a temperature sensor as temperature detection means for detecting the outlet temperature that has been raised in temperature. The same hot water temperature can be detected by, for example, the temperature sensor 64 installed in the circulation circuit 2 at the downstream end side position of the auxiliary heat source machine bypass passage 61. The temperature sensor 64 is replaced with the temperature sensor 62 described above. You may make it install.

  In the water supply circuit 4, the upstream end of the main water supply channel 41 is connected to an external water pipe or the like, and the downstream end is connected via a check valve 42 to the circulation circuit 2 near the bottom 32 of the hot water tank 3. Water can be supplied to the bottom 32 of the tank 3 or can be supplied downstream of the circulation circuit 2. A mixed water supply passage 44 branched from the upstream side of the main water supply passage 41 via a check valve 43 is connected to a later-described second mixing valve 54 of the hot water supply circuit 5 so that water can be supplied. In addition, the code | symbol 46 of FIG. 1 is a water supply temperature sensor which detects the temperature of the water supplied by the water supply circuit 4. FIG.

  The hot water supply circuit 5 has an upstream end connected to the branch point 26 of the circulation circuit 2 and is connected so as to branch from the circulation circuit 2, and a downstream of the hot water supply path 53 connected to the hot water tap 50. A second mixing valve 54 interposed in the hot water supply passage 53 and a hot water supply temperature sensor 55 disposed at a downstream position of the second mixing valve 54 are provided. The second mixing valve 54 has a predetermined setting by mixing hot water supplied from the upstream side of the hot water supply channel 53 and water supplied from the mixed water supply channel 44 at a predetermined mixing ratio (mixed water). Hot water is supplied to the hot water tap 50 after adjusting the temperature to the hot water supply temperature. The hot water supply temperature sensor 55 detects the temperature of the hot water to be finally supplied after temperature control and outputs the detected temperature to the controller 10. Based on the output from the hot water supply temperature sensor 55, the second mixing is performed. Temperature control by the valve 54 is performed by the controller 10.

  In the hot water supply path 53, hot water is supplied as hot water from the top 33 of the hot water tank 3 through the top circuit portion 27 and the branch point 26 in the hot water storage single hot water mode, and in the auxiliary heating hot water mode, the hot water tank 3 is supplied. Hot water is taken out from the top 33 of the water and supplied to the liquid-liquid heat exchanger 21 and the auxiliary heat source machine 6 through the take-out path 51 and the first mixing valve 52, and the hot water after the auxiliary heating is supplied as hot water for hot water supply through the branch point 26. It has come to be. In addition, the code | symbol 56 in FIG. 1 is an avoidance valve for preventing and avoiding hot water supply of high temperature water resulting from an apparatus abnormality.

  The auxiliary heat source unit 6 is constituted by an instantaneous water heater, for example, and is interposed in the middle of the circulation circuit 2. When the combustion operation is performed by a command from the controller 10, the hot water flowing from one side of the circulation circuit 2 is heat-exchanged and heated by the combustion heat, and the heated hot water is discharged to the other side of the circulation circuit 2, thereby circulating circuit 2 Auxiliary heating of hot water flowing through The auxiliary heat source unit 6 is configured such that a predetermined combustion operation control is performed by the controller 10 based on an output from a temperature sensor 63 provided on the outlet side thereof.

  The heating circuit 7 extends the low-temperature heat medium taken out from the expansion tank 71 by the operation of the circulation heating pump 70 to one side from the branch point 72 and heats it by liquid-liquid heat exchange in the heat exchanger 73 to generate high-temperature heat. And a high-temperature heating medium circuit 75 that circulates and supplies this to a high-temperature heating terminal (for example, a bathroom dryer) 74 and a low-temperature heating terminal (for example, floor heating) from the branch point 72 to the other side via a bypass heat valve 76. A low-temperature heat medium circuit 78 that circulates and supplies a low-temperature heat medium to 77, 77,. In addition, a high-temperature bypass circuit 80 that branches from the middle of the high-temperature heat medium circuit 75 and joins to the low-temperature heat medium circuit 78 downstream of the bypass heat valve 76 via the check valve 79 is provided. The high-temperature heat medium heated at 73 can be combined with the low-temperature heat medium supplied via the bypass heat valve 76 to raise the temperature. The heat medium that has been radiated from the low temperature heating terminals 77 and the high temperature heating terminals 74 to a low temperature is returned to the expansion tank 71.

  And as a heating source (heat source for heating) of the liquid-liquid heat exchange in the heat exchanger 73, predetermined hot water is circulated and supplied from the circulation circuit 2 to the heat source side of the heat exchanger 73. . That is, when the on-off valve 29a is opened, predetermined hot water is supplied as a heating heat source to the heat exchanger 73 through the heat source supply path 29 branched from the branch point 24 of the circulation circuit 2, and the temperature is changed by liquid-liquid heat exchange. The lowered hot water is led out to the circulation circuit 2 through the on-off valve 29a, and is circulated through the circulation circuit 2 through various paths. If the operation of the heating circuit 7 is stopped (the circulation pump 70 is stopped), when the on-off valve 29a is opened, the hot water in the circulation circuit 2 branches from the branch point 24 and flows into the heat source supply path 29, and heat is generated. By passing through the exchanger 73 and returning to the circulation circuit 2, it is circulated while bypassing the hot water tank 3.

  The bath reheating circuit 9 operates the reheating pump 91 to circulate hot water in the bathtub 92 through the recirculation path 93 and the heat exchanger 94, and the liquid-liquid heat in the heat exchanger 94 is obtained. It is designed to heat up by exchanging. Predetermined hot water is supplied to the heat source side of the heat exchanger 94 as a heat source for reheating the bath through a heat source supply path 95 branched from the branch point 25 of the circulation circuit 2 on the downstream side of the auxiliary heat source machine 6. The hot water whose temperature has decreased due to heat exchange passes through the on-off valve 95a and is led out to the circulation circuit 2 between the bottom 32 of the hot water tank 3 and the first mixing valve 52 in the same way as the heating circuit 7, Will be circulated through. Also in this case, when the on-off valve 95a is opened in the state where the chasing operation is not performed, the hot water in the circulation circuit 2 branches off from the branch point 25 and flows into the heat source supply path 95, and passes through the heat exchanger 94. By returning to the circulation circuit 2, the hot water tank 3 is circulated in a bypassed state.

  The operation of each of the circuits 2, 5, 7, and 9 described above is performed by outputting input setting signals and operation signals from the remote controller 101, and from various temperature sensors 31, 46, 55, 62 (or 64), 63, and the like. In response to the output of the detection signal, the operation is controlled by the controller 10. For such operation control, the controller 10 performs various controls such as a heating control unit and / or a reheating control unit as an external heat load control unit in addition to the exhaust heat hot water storage operation control unit and the hot water supply control unit. I have.

  Hereinafter, the characteristic exhaust heat hot water storage operation control of the present embodiment will be described with reference to FIG. FIG. 2 shows the exhaust heat and hot water storage operation control means 102 and each control unit for executing the exhaust heat and hot water storage operation control. The exhaust heat and hot water operation control means 102 includes a circulation pump adjustment control unit 103 and a mixing amount adjustment control. A mixing valve adjustment control unit 104 as a part and a heating circuit opening control unit 105 as an external heat load opening control unit. Each of these controllers 103, 104, 105 is sequentially controlled in accordance with the temperature detected by the temperature sensor 62 on the outlet side of the liquid-liquid heat exchanger 21 (detected outlet temperature). That is, if the detection outlet temperature does not reach the target hot water storage temperature (hot water storage target temperature; for example, 75 ° C. or higher) even after heat exchange heating in the liquid-liquid heat exchanger 21, the control proceeds to the next countermeasure control in order. The temperature rise of the circulating hot water is increased to reach the target temperature.

  The basics of the exhaust heat storage operation control by the exhaust heat storage operation control means 102 are started on the condition that the gas engine 1 is being driven and the engine cooling water is at a predetermined temperature or higher. As shown in FIG. 5), the take-out path 51 side of the first mixing valve 52 is closed at 0%, that is, the circulation circuit 2 side from the bottom 32 of the hot water tank 3 is set at 100% opening, The circulation pump 12 of the medium circulation path 11 and the circulation pump 22 of the circulation circuit 2 are operated together. Then, the hot water in the hot water storage tank 3 is taken out from the bottom part 32 by the circulation circuit 2, passes through the first mixing valve 52 and the liquid-liquid heat exchanger 21, and passes through the auxiliary heat source unit bypass 61, the branch point 26, and the top part. The circulation of returning to the top 33 of the hot water tank 3 through the side circuit portion 27 is repeated. On the other hand, since the engine-cooling water is supplied from the gas engine 1 to the liquid-liquid heat exchanger 21 through the heat medium circulation path 11, the circulating hot water in the circulation circuit 2 is cooled by the engine-cooling in the liquid-liquid heat exchanger 21. Heat exchange heating is performed by liquid-liquid heat exchange with water, and the heated hot water is sequentially returned to the top 33 of the hot water tank 3 so that the hot water temperature in the hot water tank 3 rises, and this is repeated to store heat. Will be.

  The above is the basic control of the exhaust heat hot water storage operation control. During this control, the temperature of the detection outlet from the temperature sensor 62 is monitored, and the detection outlet temperature reaches the preset hot water storage target temperature. If not, the circulation pump adjustment control unit 103 is first executed as countermeasure control. The circulation pump adjustment control unit 103 changes and adjusts stepwise or continuously so as to reduce the discharge flow rate of the circulation pump 22, and sequentially reduces the flow rate of the circulating hot water passing through the liquid-liquid heat exchanger 21. Even if the exhaust heat on the heat source side is poor, the temperature rise by heat exchange heating is increased so that the circulating hot water is heated to the hot water storage target temperature. Then, if the detection outlet temperature reaches the hot water storage target temperature at a change adjustment stage of a certain discharge flow rate, heat is continuously stored in the hot water storage tank 3 as it is.

  On the other hand, even if the discharge flow rate of the circulation pump 22 is changed and adjusted to the lower limit by the circulation pump adjustment control unit 103, if the detected outlet temperature does not rise to the hot water storage target temperature, then the mixing valve The adjustment control unit 104 is executed. In the mixing valve adjustment control unit 104, the opening degree of the first mixing valve 52 on the take-out path 51 side is increased stepwise or continuously from 0%, that is, the inflow of hot water from the take-out path 51 side is allowed. The amount is gradually increased, and the opening degree is gradually or continuously reduced from 100% on the side of the circulation circuit 2 from the bottom 32 of the hot water tank 3 by the increased amount. Due to the change adjustment by the mixing valve adjustment control unit 104, as shown in FIG. 4 (the portion where the flow is generated is indicated by a thick line), the extraction path 51 and the first mixing valve are provided on the inlet side of the liquid-liquid heat exchanger 21. A part of the return hot water from the top side circuit part 27 starts to flow in through 52 and gradually increases, and instead, the inflow amount of the circulating hot water from the bottom 32 of the hot water tank 3 is reduced. At the same time, the other part of the return hot water from the top side circuit part 27 flows into the hot water tank 3 from the top 33 and is stored therein, and the amount of this inflow is gradually reduced. Thereby, even if the heat quantity of the exhaust heat supplied to the heat source side of the liquid-liquid heat exchanger 21 is small, the flow rate of the lower temperature circulating hot water supplied from the bottom 32 of the hot water tank 3 is relatively reduced. The temperature rise of the circulating hot water passing through the liquid-liquid heat exchanger 21 is increased as compared with the case of the circulation pump adjustment control unit 103, and the temperature is easily raised to the hot water storage target temperature.

  Then, if the detected outlet temperature reaches the hot water storage target temperature at a change adjustment stage in which each opening degree of the first mixing valve 52 is changed, heat is continuously stored in the hot water tank 3 as it is. On the other hand, if the detection outlet temperature does not reach the hot water storage target temperature, the change adjustment of the first mixing valve 52 is continued, and finally, the circulation circuit 2 side from the bottom 32 of the hot water tank 3 has a small opening of a certain limit. If the detection outlet temperature does not reach the hot water storage target temperature even when the take-out path 51 side reaches a certain large opening, the third stage heating circuit opening control unit 105 is also executed.

In the heating circuit opening control unit 105, the on-off valve 29a is opened and switched to divert the circulating hot water from the branch point 24, and after passing through the heat source supply path 29, the heat exchanger 73 and the on-off valve 29a, from the bottom 32 of the hot water tank 3. Is supplied to the circulation circuit 2. As a result, as shown in FIG. 5 (the portion where the flow is generated is indicated by a thick line), the circulating hot water exiting the liquid-liquid heat exchanger 21 is divided into the top circuit portion 27 side and the heat source supply path 29 side. Then, the circulating hot water divided to the heat source supply passage 29 side is circulated through the circulation circuit 2 bypassing the hot water tank 3. For this reason, the ratio of the low-temperature hot water flowing out from the bottom 32 of the hot water tank 3 in the circulating hot water circulated and supplied to the inlet side of the liquid-liquid heat exchanger 21 can be reduced as much as possible. As a result, even if the heat quantity of exhaust heat, which is a heat source circulated and supplied to the liquid-liquid heat exchanger 21, is insufficient, the temperature of the circulating hot water can be raised sufficiently.
Furthermore, when the hot water storage target temperature cannot be finally reached, the process returns to the mixing valve adjustment control unit 104, and the circulation circuit 2 side from the bottom 32 of the hot water tank 3 is used as the first mixing valve 52 change adjustment amount. 0%, that is, close, change the opening of the take-out path 51 to 100%, and temporarily stop the heat storage in the hot water tank 3 as shown in FIG. All the circulating hot water is circulated through the liquid-liquid heat exchanger 21, the auxiliary heat source unit bypass path 61, the branch point 26, the top side circuit part 27, the extraction path 51, and the first mixing valve 52. This circulation control makes it possible to increase the temperature of the circulating hot water even when the amount of exhaust heat, which is a heat source circulated and supplied to the liquid-liquid heat exchanger 21, is extremely small. When the hot water storage target temperature is reached, the take-out path 51 side of the first mixing valve 52 is slightly throttled, and the side of the circulation circuit 2 from the bottom 32 of the hot water tank 3 is changed slightly to change the hot water storage temperature. What is necessary is just to make it flow in little by little with respect to the top part 33 of the tank 3, and to store hot water.

  According to the above exhaust heat storage operation control, even when the heating capability of the exhaust heat supplied to the liquid-liquid heat exchanger 21 as a heat source for heating is poor, the control for heating the circulating hot water to the hot water storage target temperature is performed. It can be done easily and reliably. In addition, it is possible to respond by changing the control stepwise or continuously in accordance with the heating capacity of the exhaust heat, thereby efficiently using the amount of heat of the exhaust heat to bring the circulating hot water to the target hot water storage temperature. The temperature can be raised.

<Other embodiments>
In addition, this invention is not limited to the said embodiment, Other various embodiment is included. That is, in the said embodiment, the case where the external heat source which is the object of the exhaust heat recovery which stores hot water in the hot water storage tank 3 is made into the gas engine (engine cooling water exhaust heat) was shown, but not limited to this, as an external heat source The fuel cell (cooling water exhaust heat), heat pump (refrigerant exhaust heat), or solar heat (solar heat collection) may be used to store heat as hot water storage. can do.

  In the embodiment, the auxiliary heat source unit bypass path 61 is provided, and the circulating hot water is passed through the auxiliary heat source unit bypass path 61 in the exhaust heat hot water storage operation control. However, the present invention is not limited thereto, and the auxiliary heat source unit bypass path 61 is omitted. In the exhaust heat hot water storage operation control, the circulating hot water may be passed through the auxiliary heat source unit 6 in the non-combustion state.

  In the above embodiment, the heating circuit opening control unit 105 is shown as the external heat load circuit opening control unit. However, the present invention is not limited to this, and the open / close valve 95a is used as the external heat load circuit opening control unit instead of the heating circuit opening control unit 105. The control by the reheating circuit opening control unit for releasing the heating circuit may be executed, or the heating circuit opening control unit and the reheating circuit opening control unit may be executed together.

1 Gas engine (external heat source)
2 Circulation circuit 3 Hot water tank 8 Heating circuit (external heat load circuit)
9 Bath chasing circuit (external heat load circuit)
21 Liquid-liquid heat exchanger (exhaust heat recovery section)
32 bottom 33 top 51 take-out path 52 first mixing valve (mixing means)
62 Temperature sensor (temperature detection means)
102 Waste heat storage operation control unit (exhaust heat storage operation control means)
103 Circulation pump adjustment control unit 104 Mixing valve adjustment control unit (mixing amount adjustment control unit)
105 Heating circuit open control unit (external heat load circuit open control unit)

Claims (1)

A hot water storage tank for storing heat as hot water by recovering exhaust heat from an external heat source, and a circulation circuit for circulating hot water taken from the bottom of the hot water storage tank back to the top of the hot water storage tank; In addition, a variable discharge flow rate circulation pump for circulating the hot water and a waste heat recovery unit that heats the circulating hot water by recovering the exhaust heat from the external heat source are interposed, from the exhaust heat recovery unit Also, the external heat load circuit and the extraction path are branched from the circulation circuit at the downstream position, and the downstream end of the external heat load circuit is connected to the circulation circuit from the bottom of the hot water tank so as to bypass the hot water tank. The take-out path is a control device for a hot water system, the downstream end of which is connected to a circulation circuit at an upstream position of the circulation pump via a mixing means,
Waste heat storage operation control for operating the circulation pump to circulate hot water in the hot water storage tank to the circulation circuit, raising the temperature to a hot water storage target temperature by exhaust heat recovery in the exhaust heat recovery section, and storing hot water in the hot water storage tank Means, and temperature detecting means for detecting the temperature of the circulating hot water after exhaust heat recovery at the outlet side of the exhaust heat recovery unit,
The exhaust heat hot water storage operation control means, as a control part for executing countermeasure control according to the detected temperature of the circulating hot water by the temperature detection means, a circulation pump adjustment control part for changing and adjusting the discharge flow rate of the circulation pump, A mixing amount adjustment control unit for increasing and changing the mixing flow rate on the take-out path side in the mixing means, and an external heat load circuit for opening the on-off valve provided in the external heat load circuit and diverting the circulating hot water from the circulation circuit An opening control unit ,
The mixing amount adjustment control unit is configured to be executed when the circulating hot water does not reach a target hot water storage temperature even when the circulation pump adjustment control unit changes and adjusts the discharge flow rate.
The external heat load circuit opening control section that is configured to run when the mixing amount adjustment control unit the extraction path side mixed flow circulating hot water Changing increase in the does not reach the target hot-water temperature ,
Control device of warm water system, characterized in that.

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