JP4656994B2 - Hot water storage hot water supply device - Google Patents

Description

  The present invention comprises a hot water storage tank and circulating water heating means, and has at least a mechanism for exchanging heat with the hot water on the heat load side such as floor heating or bathing in the hot water in the hot water tank. The present invention relates to a hot water supply device.

  Hot water storage type hot water supply devices are known. Usually, a hot water storage type hot water supply device includes a hot water storage tank, a first hot water circulation path connecting the lower and upper parts of the hot water storage tank, circulating water heating means provided in the first hot water circulation path, It has a hot water supply channel that supplies hot water directly to a bath and the like, and a water supply channel that supplies the hot water in the tank. In addition, there is also a device that includes a second hot water circulation path and supplies the heat of the hot water in the hot water tank to a heat load (floor heating, bathing, etc.) arranged there.

  The hot water in the hot water storage tank forms a temperature stratification in which the upper part of the tank is hot and the lower part of the tank is cold. The low-temperature water in the lower part of the tank is heated to a predetermined temperature (for example, 60 ° C.) by the circulating water heating means provided in the first hot water circulation path from the lower part to the upper part, and flows into the upper part of the tank again. To do.

  Hot water in the hot water tank is supplied directly from the hot water supply path to the bath or the like from the upper part of the tank, and the amount of water supplied is replenished into the hot water storage tank from the lower part of the tank through the water supply path. The second hot water circulation path has a hot water outlet at the top of the tank and a hot water return opening at the bottom of the tank, and hot water in the hot water tank is suitably used as in floor heating in the process of circulating through the second hot water circulation path. The heat water is radiated by heat exchange and heat exchange, and the hot water that has become low temperature is returned to the hot water tank again.

  In such a hot water storage type hot water supply device, a heat pump unit is often used as a heating source, so as to improve heat exchange with hot water supply to a hot water storage tank or an external heat load, or to reduce the boiling performance of the heat pump unit. In order to prevent this, various proposals have been made for the purpose (see Patent Document 1, Patent Document 2, etc.).

  In the thing of patent document 1, while enabling the hot water supplied to the heat load side to be switched to the hot water at the upper part of the hot water tank and the hot water heated by the heating means, the low temperature water that is the return water from the heat load side is changed. It can be supplied directly to the heating source. In the thing of patent document 2, in view of the return hot water from the heat load side being medium temperature hot water, the return hot water is returned to the hot water storage tank from the intermediate part of the hot water storage tank, Mixing with return hot water is prevented, and the heat pump unit preferentially heats itself at the lowermost part of the hot water storage tank, thereby preventing the boiling performance of the heat pump unit from deteriorating.

JP 2000-121157 A JP 2004-183920 A

  In order to efficiently operate the hot water storage type hot water supply device, it is necessary to make various contrivances in the hot water circulation system, etc. according to the form of the heating means for heating the hot water in the hot water tank, Proposals have already been made when the heat source is a heat pump. In recent years, since the load on the environment is small, the use of a fuel cell as a power source has attracted attention in various fields. In the field of the hot water storage type hot water supply device described above, a fuel cell, particularly room temperature to 100 Attempts have been made to use the heat generated when operating a PEFC (Polymer Electrolyte Fuel Cell) that can be operated at a temperature of about 0C. This method also has an advantage that the electricity generated by the operation of the fuel cell can be used without waste.

  By the way, when a fuel cell (for example, a polymer electrolyte fuel cell) is used for heating hot water stored in a hot water storage tank of a hot water storage type hot water supply device, the fuel cell outlet temperature (that is, heat generated during operation of the fuel cell is heated). When the temperature of the hot water supplied from the lower part of the hot water tank is low, the flow rate is controlled so that the temperature of the recovered hot water becomes a constant temperature (for example, about 60 ° C). The flow rate at the inlet to the fuel cell (that is, the flow rate when entering the fuel cell side to recover the heat generated by the operation of the fuel cell) is reduced. Therefore, operation must be performed in a state where the fuel cell-side circulation flow rate is low. Therefore, the flow rate of the hot water supplied into the hot water storage tank is reduced, the high temperature water in the hot water storage tank is decreased, the low temperature water is increased, and there is a possibility that sufficient heat cannot be supplied to the heat load side.

  An object of the present invention is to eliminate the inconvenience as described above when heat generated during operation of a fuel cell is used for heating hot water stored in a hot water storage tank of a hot water storage type hot water supply device. It is an object of the present invention to provide a hot water storage type hot water supply device that can be operated for a long time while the hot water temperature is stably maintained at a predetermined temperature.

  A hot water storage type hot water supply apparatus according to the present invention includes a hot water storage tank, first and second hot water circulation paths connecting the lower and upper parts of the hot water storage tank, and circulating water heating means provided in the first hot water circulation path, A hot water storage type hot water supply device comprising at least a heat load provided in the second hot water circulation path and a control means for controlling operation, wherein the circulating water heating means provided in the first hot water circulation path is a fuel cell. The second hot water circulation path has a branch hot water path in the hot water return circuit portion from the heat load to the lower part of the hot water tank, and recovers the heat generated during the operation to heat the circulating water. The branch hot water passage is connected to the hot water circulation passage from the lower part of the hot water tank of the first hot water circulation passage to the heating means via a flow rate adjusting valve, and the control means flows into the first hot water circulation passage from the branch hot water passage. It is configured to give a signal to control the amount of hot water to be supplied to the flow control valve. The features.

  In the above apparatus, heat generated during operation of the fuel cell is used as a heat source for heating the hot water in the hot water tank, that is, a heat source for the circulating water heating means provided in the first hot water circulation path, Operation with low environmental impact is possible.

  Also, during operation, if the temperature of the return hot water from the heat load side is higher than the temperature of the stored water in the lower part of the hot water tank, supply all or part of it directly to the fuel cell side via the branch hot water channel. As a result, the flow rate of the high-temperature water on the fuel cell outlet side can be increased, and as a result, a large amount of high-temperature water can be supplied into the hot water tank in a short time. Thereby, high temperature water can be continuously supplied to the heat load side. On the contrary, when the temperature of the return hot water from the heat load side is lower than the temperature of the stored water at the lower part of the hot water tank, the entire amount or a large amount is returned to the hot water tank without returning to the fuel cell side.

  In any case, the turbulence of temperature stratification in the hot water tank can be suppressed by returning all or part of the return hot water from the heat load side directly to the fuel cell side.

  In the apparatus of the present invention, the flow rate adjusting valve may be disposed at a branch portion between the second hot water circulation path and the branch hot water path, or may be disposed at a junction portion between the branch hot water path and the first hot water circulation path. Also good. You may install in both and selectively use according to an operating environment, or you may make it use both simultaneously.

  In the apparatus of the present invention, it is not necessary in an environment where only a closed hot water circulation path (second hot water circulation path) is operated, but preferably, a hot water supply path and a hot water tank for supplying hot water from a hot water tank as hot water to a bath or the like are preferable. And a water supply channel for supplying tap water. In this case, since tap water is supplied into the hot water tank, the temperature of the stored water at the lower part of the hot water tank is lowered, and the temperature difference from the return hot water from the heat load side is increased. The hot water storage type hot water supply device according to FIG.

  According to the present invention, in a hot water storage type hot water supply apparatus in which heat generated during operation of a fuel cell is used for heating hot water stored in a hot water tank, a large amount of high temperature water can be supplied into the hot water tank in a short time. This makes it possible to continuously supply hot water to the heat load side.

  Hereinafter, referring to the drawings. The present invention will be described based on an embodiment. FIG. 1 is a schematic configuration diagram illustrating a hot water storage type hot water supply device according to the present invention, and FIGS. 2 and 3 are two schematic configuration diagrams illustrating a hot water supply system using the hot water storage type hot water supply device according to the present invention. is there.

  The hot water storage type hot water supply apparatus shown in FIG. 1 includes a hot water storage tank 10, a fuel cell 20, and a heat exchanger 30 on the heat load side. The hot water storage tank 10 may be a hot water storage tank used in a conventional hot water storage type hot water supply apparatus, and as indicated by a virtual line, a hot water supply path 11 is provided above the hot water storage tank 10 and a water supply path is provided below the hot water storage tank 10. 12 may be provided.

  In this example, the fuel cell 20 is a conventionally known PEFC (Polymer Electrolyte Fuel Cell) and will not be described in detail. The fuel cell 20 is provided with a heat recovery path 21 for recovering heat generated during operation (power generation). The inlet side of the heat recovery path 21 is connected to the lower part of the hot water tank 10 through an inlet pipe line 22. The outlet side of the heat recovery path 21 is connected to the upper part of the hot water tank 10 by an outlet pipe 23. The inlet pipe 22, the heat recovery path 21 and the outlet pipe 23 constitute the “first hot water circulation path” in the present invention, and the heat recovery path 21 is “circulated water provided in the first hot water circulation path”. Constitutes "heating means".

  By the operation of a pump (not shown), for example, low-temperature water in the lower layer of the hot water tank 10 having a temperature of about 20 ° C. is sent from the inlet pipe 21 to the heat recovery path 21, where the generated heat is recovered from the fuel cell 20. The temperature is raised to about 0 ° C., and flows into the tank from the upper part of the hot water tank 10 through the outlet pipe 23.

  A hot water feed pipe 32 from the upper part of the hot water tank 10 is connected to the inlet of the heat exchange path 31 of the heat exchanger 30, and hot water connected to the lower part of the hot water tank 10 is connected to the outlet of the heat exchanger 31. A return line 33 is connected. The hot water feed pipe 32, the heat exchange path 31, and the hot water return pipe 33 constitute the “second hot water circulation path” in the present invention. Note that a hot water circulation path 40 from an appropriate heat load side (not shown in FIG. 1) enters the heat exchanger 30, and performs heat exchange with the heat exchange path 31. Although not shown, the heat exchange path 31 itself may form a hot water circulation path on the heat load side.

  The hot water return pipe 33 has a branch portion 34 having a flow rate adjusting valve, and a branch hot water path 35 is branched therefrom. The branch hot water passage 35 is connected to the inlet conduit 22 constituting the first hot water circulation passage at the junction 24. The junction 24 is also provided with a flow rate adjusting valve. A temperature sensor S is attached upstream of the branch portion 34 of the hot water return pipe 33, and the temperature signal is sent to the control means C. The control means C gives a signal corresponding to the temperature signal from the temperature sensor S to the branching section 34 and / or the merging section 24 to control the branch flow rate to the branch hot water passage 35. Further, the control means C gives a signal corresponding to the temperature signal from the temperature sensor S to the junction 24, and controls the hot water flow rate from the hot water tank 10 and the hot water flow rate from the branch hot water channel 35 in the inlet conduit 22. .

  The operation mode of the above apparatus will be described based on a specific example. As shown in FIG. 1, the flow rates in the respective flow paths described above are indicated by Q1 to Q6 (L / min). That is, the circulation flow rate of the first hot water circulation channel is Q1, the circulation flow rate of the second hot water circulation channel is Q2, the return flow rate to the lower part of the hot water tank 10 is Q3, the flow rate flowing through the branch hot water channel 35 is Q4, and the junction 24 Q5 is the flow rate returning to the hot water storage tank 10 from the inlet pipe 22 to Q5, and Q6 is the return flow rate from the junction 24 of the inlet pipe line 22 to the fuel cell 20. Further, the temperature of the circulating hot water at the inlet (° C.) of the fuel cell 20 is T1, the outlet temperature is T2, the inlet temperature at the heat exchanger 30 is T3, and the outlet temperature is T4.

  And as shown in Table 1, the driving | running state of an apparatus is demonstrated about four cases.

  In cases 1 to 4, it is assumed that 1.5 kW of heat is generated from the fuel cell 20 due to its operation. Further, it is assumed that the heat loads in the heat exchangers 30 of the cases 1 and 2 are the same and the heat loads in the heat exchangers 30 of the cases 3 and 4 are the same.

  Case 1 is a case in which the hot water that has exited the heat exchanger 30 is not flowed (not diverted) into the branch warm water flow path 35. In this case 1, T1: 20 ° C. warm water is sent from the lower part of the hot water tank 10 to the fuel cell 20 side at a flow rate (flow rate of the first hot water circulation path) Q1: 0.5 L / min. The heat generated during the operation is recovered, T2 rises to 60 ° C., and is returned to the hot water tank 10. To the heat load side (heat exchanger 30), high temperature water at T3: 60 ° C. is fed from the upper part of the hot water tank 10 at the second hot water circulation flow rate Q2: 2 L / min, and after heat exchange with the heat load side, T4 : All of them (flow rate Q3) are returned to the hot water storage tank 10 in a state where the temperature is lowered to 35 ° C. In this operation state, the temperature T1 of the hot water that comes out from the lower part of the hot water tank 10 and is sent to the fuel cell 20 side during the operation is considered that the tap water is supplied into the tank from the water supply path 12. In order to maintain the temperature of T2 at 60 ° C., the first hot water circuit flow rate Q1 is around 0.5 L / min, and a flow rate higher than that cannot be flowed.

Case 2 controls the flow rate adjustment valve provided in the branch part 34 of the hot water return pipe 32, and the return flow (second hot water circuit flow rate) Q2 coming out of the heat exchanger 30 is 2L / min. This is a case where the flow rate Q4 of the branch hot water passage 35 is set. Therefore, the hot water tank return flow rate Q3 is 0 L / min. In this case, since the temperature T1 of the hot water sent to the fuel cell 20 side is 35 ° C., the flow rate Q1 required to maintain the temperature of T2 at 60 ° C. is about 0.8 L / min. In the hot water tank 10, hot water at 60 ° C. can be made 1.6 times faster. In this case, the flow rate Q4: 2 L / min of the branch warm water channel 35 is adjusted by the flow rate adjusting valve arranged in the junction 24 by a signal from the control means C, so that the flow rate Q6: 0 to the fuel cell 20 side is adjusted. .8 L / min, flow rate Q5 returning to the hot water tank 10 side: 1.2 L / min.

  Case 3 is the same as Case 1 in the case of returning the entire return flow rate (second hot water circuit flow rate) Q2: 2 L / min from the heat exchanger 30 to the hot water tank 10 as a flow rate Q3: 2 L / min. However, here, the outlet temperature T4 of the heat exchanger 30 is set to 45 ° C. in relation to the heat load capacity. Here, as in the case 1, the temperature T1 of the hot water that comes out from the lower part of the hot water storage tank 10 and is sent to the fuel cell 20 side during the operation is considered to be supplied from the water supply channel 12 into the tank. In order to maintain the temperature of T2 at 60 ° C., the first hot water circuit flow rate Q1 is about 0.5 L / min.

  The case 4 is a flow rate in which the flow rate of the hot water (second hot water circulation path flow rate Q2) at the outlet temperature T4: 45 ° C. exiting from the heat exchanger 30 in the case 3 is provided in the branch portion 34 of the hot water return line 32. This is a case where the adjustment valve and the flow rate adjustment valve arranged in the junction 24 are appropriately controlled so that the hot water temperature T1: 40 ° C. flowing into the fuel cell 20 is controlled. If T1 is controlled to be 40 ° C., the flow rate Q1 for maintaining T2 at 60 ° C. can be increased to 1.0 L / min, and 60 ° C. hot water can be produced at twice the speed of case 3. Become. As specific control, for example, a flow rate adjusting valve provided in the branching section 34 is controlled, and the return flow rate Q3 to the hot water tank 10 is 1.2 L / min, and the flow rate Q4 to the branch hot water passage 35 is 0.8 L. To the fuel cell 20 by adding hot water at a flow rate Q5: 0.2 L / min from the lower part of the hot water tank 10 to Q4. The flow rate Q6, that is, Q1 is set to 1.0 L / min.

  As described above, in the hot water storage type hot water supply apparatus that recovers and uses the heat generated by the operation of the fuel cell as a heating source, the heat exchanger (heat load) 30 in the second hot water circulation path is connected to the lower part of the hot water tank 10. A branch hot water passage 35 is provided in the hot water return circuit portion 33, and a downstream side of the branch hot water passage 35 is connected to the hot water circulation passage 22 from the lower part of the hot water storage tank 10 of the first hot water circulation passage to the fuel cell 20 via a flow rate adjustment valve. And by appropriately controlling the amount of warm water Q4 flowing into the first warm water circulation path 22 from the branch warm water path 35, it is possible to store the warm water at a predetermined temperature in the hot water storage tank 10 in a shorter time. Become.

  In the above description, two modes in which the heat exchanger outlet temperature T4 is 35 ° C. and 45 ° C. have been described. However, when the actual machine is operated, T4 varies depending on the capacity on the heat load side. The temperature sensor S constantly monitors the fluctuating temperature, and upon receiving the signal, the control means transmits an opening degree signal to the flow rate adjusting valve so as to obtain an optimum operation state. Further, when T4 is lower than the tap water temperature, the entire amount or a large amount of return water is returned to the bottom of the hot water tank 10.

  FIG. 2 shows an example of a system that actually uses the hot water storage type hot water supply apparatus. The same members as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted to avoid duplication. Here, floor heating, bath remembrance, etc. are illustrated as the thermal load 41. The hot water supply passage 11 from the hot water storage tank 10 is provided with a three-way valve 14, one of which is connected to the hot water supply path 12 to the hot water storage tank 10 by a pipe line 15, and the other is supplied with hot water such as a bath 44 through an auxiliary heat source device 43. Connected to the field. The auxiliary heat source unit 43 performs additional heating of hot water flowing through the hot water supply passage 11 and additional heating of hot water flowing through the hot water circulation passage 40 on the heat load 41 side as necessary. The electricity generated by the fuel cell 20 is supplied to the power load 46 together with the commercial power supply 45. Reference numerals 34a and 34b denote flow rate adjusting valves arranged in the branch portion 34, and P denotes a circulation pump.

  In the above system, the outlet temperature T4 of the circulating water from the heat exchanger 30 is measured by the temperature sensor S, and the temperature information is sent to the control means C. Based on the temperature information, the control means C adjusts the opening degree of the two flow control valves 34 a and 34 b provided in the branch section 34, and changes the flow rate Q 2 flowing through the hot water return pipe 32 to the lower flow rate of the hot water tank 10. It distributes in the range of 0-100 each to Q3 and the flow volume Q4 to the branch warm water flow path 35. The distribution ratio is optimally set according to the amount of hot water supply and the state of the heat load, and further according to the operating state of the fuel cell 20 based on the power load. As described, by performing such distribution, it becomes possible to store hot water at a required temperature in the hot water storage tank 10 in a short time, and the operation time of the auxiliary heat source unit 43 can be reduced. Energy-saving operation is possible.

  FIG. 3 shows another example of a system that actually uses the hot water storage type hot water supply apparatus. Here, unlike the system shown in FIG. 2, the branch section 34 merely branches the branch hot water flow path 35, and does not include the flow rate control valves 34 a and 34 b. Instead, the merging portion 24 is provided with a three-way valve 50 having a flow rate adjusting function, and the control means C adjusts the opening degree of the three-way valve 50 based on the temperature information from the temperature sensor S to branch. The flow rate Q4 to the hot water flow path 35, the fuel cell return flow rate Q6, and the hot water tank return flow rate Q5 are appropriately adjusted. As a result, the hot water tank return flow rate Q3 is also set as Q2-Q4. The other configurations are the same as those shown in FIG. 2, and the same members are denoted by the same reference numerals, and the description thereof is omitted. As described based on the cases 3 and 4 described above, this system is preferably used when the fuel cell inlet temperature T1 is set to a desired temperature for operation.

  Although not shown in the drawing, as shown and described in the schematic configuration diagram of FIG. 1, a valve having a flow rate adjusting function is arranged in both the branching section 34 and the merging section 24, and both are detected by the temperature sensor S. Based on the outlet temperature T4 from 30, the control means C may control the temperature appropriately. Further, the return hot water temperature T4 from the heat load side is constant in a certain temperature range, and the total flow rate Q4 divided by the branch portion 34 of the hot water return pipe 33 and the branch hot water path 35 is supplied to the fuel cell 20 side as it is. In the case of such an operation mode, it is not necessary to provide a flow rate adjusting function on the merging portion 24 side, and only the branching portion 34 has a flow rate adjusting function.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram explaining the hot water storage type hot water supply apparatus by this invention. BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram explaining an example of the hot water supply system using the hot water storage type hot water supply apparatus by this invention. The schematic block diagram explaining the further another example of the hot water supply system using the hot water storage type hot water supply apparatus by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Hot water storage tank, 11 ... Hot water supply path, 12 ... Water supply path, 20 ... Fuel cell, 21 ... Heat recovery path, 22 ... Inlet pipe line, 23 ... Outlet pipe line, 24 ... Junction part, 30 ... Heat exchanger, 31 DESCRIPTION OF SYMBOLS ... Heat exchange path, 32 ... Warm water infeed line, 33 ... Warm water return line, 34 ... Branch part, 35 ... Branch warm water path, S ... Temperature sensor, C ... Control means

Claims (3)

First and second hot water circulations connecting the hot water storage tank , the hot water supply path provided in the upper part of the hot water storage tank for supplying hot water in the hot water storage tank, the water supply path provided in the lower part of the hot water storage tank, and the lower and upper parts of the hot water storage tank A hot water storage type hot water supply device comprising at least a path, a circulating water heating means provided in the first hot water circulation path, a heat load provided in the second hot water circulation path, and a control means for controlling operation There,
The circulating water heating means provided in the first hot water circulation path is a means for recovering heat generated during operation of the fuel cell to heat the circulating water, and the second hot water circulation path is heated from the heat load to the lower part of the hot water tank. The hot water return circuit part has a branch hot water passage, and the branch hot water passage is connected to the hot water circulation passage from the lower part of the hot water storage tank of the first hot water circulation passage to the heating means via a flow rate adjusting valve. The control means is configured to provide a signal for controlling the amount of hot water flowing into the first hot water circulation path from the branch hot water path to the flow rate adjusting valve, and further, the hot water supply path provided at the upper part of the hot water tank has three sides. A hot water storage type hot water supply apparatus, characterized in that a valve is provided, one of which is connected to a hot water tank with a water supply channel and a pipe, and the other is connected to a hot water supply station such as a bath via an auxiliary heat source .   The hot water storage type hot water supply apparatus according to claim 1, wherein the flow rate adjusting valve is arranged at a branch portion between the second hot water circulation path and the branch hot water path.   The hot water storage type hot water supply device according to claim 1, wherein the flow rate adjusting valve is disposed at a junction between the branch hot water passage and the first hot water circulation passage.

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