JP2008128527A - Hot water supply system and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent degradation of the heat efficiency of an entire hot water supply system while securing the capacity of a hot water storage tank. <P>SOLUTION: This hot water supply system comprises a hot water producing means 10 for producing hot water, a downstream-side hot water storage tank 21, an intermediate hot water storing portion 22 and an upstream-side hot water storage tank 23 for storing the hot water produced by the hot water producing means 10, hot water supply pipes 64, 65 for supplying the hot water stored in the downstream-side hot water storage tank 21 and the intermediate hot water storing portion 22, an intermediate water temperature sensor 32 for detecting a temperature of hot water in the intermediate storing portion 22, and a control portion 60 for selectively providing a first hot water supply state for supplying the hot water in the downstream-side hot water storage tank 21 to a hot water storing pipe, a second hot water supply state for supplying the hot water in the intermediate hot water storing portion 22 to the hot water supply pipe 64 through an intermediate pipe, and a third hot water supply state for supplying the hot water in both of the downstream-side hot water storage tank 21 and the intermediate hot water storing portion 22 to the hot water supply pipe 64 on the basis of the water temperature detected by the intermediate water temperature sensor 32. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hot water supply system and method for storing hot water heated by hot water generating means in a hot water storage tank and supplying the stored hot water.

  Heat pump water heaters are generally more energy efficient than water heaters that heat water with an electric heater because they use changes in the state of the refrigerant as the heat source, and do not burn gas, so they emit carbon dioxide into the air. It is said that the water heater is friendly to the global environment. For this reason, various heat pump type water heaters have been developed (for example, Patent Document 1).

  By the way, the heat pump type hot water heater using carbon dioxide as a refrigerant has a problem that the heating efficiency is lowered when the temperature of the water to be taken in is high, unlike the electric water heater or the hot water heater using gas. Therefore, when the warm water once warmed and stored in the hot water storage tank cools and becomes warm, if the warm water is chased by the heat pump type hot water heater, the heating efficiency is lowered.

  On the other hand, in a sealed hot water storage tank that has been widely used in the past, hot water is supplied while always keeping the tank level constant by supplying water from the lower part to the hot water storage tank by the amount of hot water supplied. Moreover, when boiled with a heat pump to store heat, cold water at room temperature is taken into the hot water storage tank from the bottom and heated with the heat pump, and the heated hot water is poured into the hot water storage tank from the top. And the hot water and cold water in a hot water storage tank are separated into a hot water layer and a cold water layer up and down by specific gravity difference. However, in practice, mixing of hot water and cold water occurs near the boundary between the hot water layer and the cold water layer to form an intermediate temperature mixed water layer, and the mixed water layer expands by repeated hot water supply and heat storage.

Thus, when the mixed water layer expands, the substantial capacity of the hot water storage tank is further reduced by that amount. In addition, when medium temperature mixed water is chased by a carbon dioxide refrigerant heat pump type water heater, the heating efficiency decreases due to the characteristics of the heat pump. Furthermore, if the generation of the mixed water layer is left unattended, the mixed water layer expands. Therefore, the problem is whether to keep the amount of the intermediate temperature mixed water layer generated in the hot water storage tank to a minimum.
JP 2003-148803 A

  With respect to such problems, the present invention uses mixed water generated by mixing hot water and cold water in a hot water storage tank for hot water supply, thereby reducing the thermal efficiency of the entire hot water supply system while ensuring the capacity of the hot water storage tank. It is an object of the present invention to provide a hot water supply system and method that can prevent the above.

1st invention, the warm water production | generation means which produces | generates warm water,
Hot water storage means for storing hot water generated by the hot water generation means;
A hot water supply pipe for supplying hot water stored in the hot water storage means,
The hot water storage means includes a first hot water storage tank directly connected to a cold water inlet of the hot water generating means, a second hot water storage tank directly connected to the hot water supply pipe, the first hot water storage tank, and the second hot water storage tank. An intermediate hot water storage unit composed of one or more intermediate hot water storage tanks connected in series with the hot water storage tank,
The hot water storage system further includes:
An intermediate pipe for supplying hot water stored in the intermediate hot water storage section to the hot water supply pipe;
An intermediate water temperature sensor for detecting the water temperature of the intermediate hot water storage unit;
Based on the water temperature detected by the intermediate water temperature sensor, a first hot water supply state in which hot water in the second hot water storage tank is supplied to the hot water storage pipe, hot water in the intermediate hot water storage section is supplied to the hot water supply pipe through the intermediate pipe. And a controller that selectively realizes a second hot water supply state or a third hot water supply state in which hot water from both the second hot water storage tank and the intermediate hot water storage portion is supplied to the hot water supply pipe. It is a hot water supply system.

2nd invention is the 1st hot water valve installed in the location connected to the said hot water supply piping from the said 2nd hot water storage tank,
A second hot water valve installed in the intermediate pipe;
With
The control unit controls the amount of hot water supplied from the second hot water storage tank and the intermediate hot water supply unit to the hot water supply pipe by adjusting the opening of the first hot water supply valve and the second hot water supply valve. A hot water supply system according to the first aspect of the invention.

  When the water temperature detected by the intermediate water temperature sensor is equal to or higher than a predetermined first water temperature or lower than a predetermined second water temperature lower than the first water temperature, The hot water supply system according to the first or second invention, wherein the first hot water supply state is realized.

  According to a fourth aspect of the invention, the control unit detects a predetermined third water temperature at which the water temperature detected by the intermediate water temperature sensor is lower than the predetermined first water temperature and lower than the first water temperature and higher than the second water temperature. When it is above, it is a hot-water supply system in any one of the 1st-3rd invention characterized by realizing the 2nd hot-water supply state.

  According to a fifth aspect of the present invention, when the water temperature detected by the intermediate water temperature sensor is lower than the third water temperature and equal to or higher than the second water temperature, the control unit realizes the third hot water supply state. The hot water supply system according to any one of the first to fourth inventions.

A sixth invention provides a hot water temperature sensor that detects a temperature of hot water in the hot water supply pipe,
A circulation system for selectively connecting the first predetermined location of the hot water supply pipe to the second predetermined location upstream of the first predetermined location of the hot water supply pipe or the hot water storage means;
Based on the water temperature detected by the hot water temperature sensor, a control unit that switches the connection destination of the first predetermined location by the circulation system to the second predetermined location or the hot water storage means;
A hot water supply system according to any one of the first to fifth inventions.

In a seventh aspect of the invention, the controller is
When the water temperature detected by the hot water temperature sensor is equal to or higher than a fourth predetermined temperature, the connection destination of the first predetermined location is the second predetermined location,
When the water temperature detected by the hot water temperature sensor is lower than the fourth predetermined temperature, the connection destination of the first predetermined location by the circulation system is the hot water storage means, and then the water temperature is the fourth temperature. In the hot water supply system according to the sixth aspect of the present invention, when a predetermined upper limit temperature higher than a predetermined temperature is reached, the connection destination of the first predetermined location by the circulation system is set as the second predetermined location. is there.

The eighth invention branches into a first branch pipe connected to the second predetermined location and a second branch pipe connected to the hot water storage means in the circulation system,
A first on-off valve is provided in the first branch pipe;
A second on-off valve is provided in the second branch pipe;
The controller is
By opening the first on-off valve and closing the second on-off valve, the connection destination of the first predetermined location by the circulation system is the second predetermined location,
The sixth or seventh invention is characterized in that the hot water storage means is the connection destination of the first predetermined location by the circulation system by closing the first on-off valve and opening the second on-off valve. It is a hot-water supply system of description.

9th invention is equipped with the hot water storage water temperature sensor which detects the water temperature of a 1st hot water storage tank,
The control unit supplies hot water stored in the second hot water storage tank to the hot water supply pipe based on the water temperature detected by the hot water storage water temperature sensor when the connection destination of the circulation system is the hot water storage means. The first circulating state to be switched and the second circulating state to be supplied to the cold water inlet of the hot water generating means by the cold water in the first hot water storage tank being pushed out by the hot water from the circulation system The hot water supply system according to any one of the sixth to eighth inventions.

In a tenth aspect of the invention, the controller is
In the case where the connection destination of the first predetermined location by the circulation system is the hot water storage means, and the hot water storage water temperature sensor exceeds the fifth predetermined temperature, switching to the first circulation state,
In the case where the connection destination of the first predetermined place by the circulation system is the hot water storage means, and when the hot water temperature sensor falls below a fifth predetermined temperature, the hot water storage temperature switch is switched to the second circulation state. It is a hot-water supply system as described in 9th invention.

In an eleventh aspect of the invention, a third on-off valve is provided in a pipe connecting the first hot water storage tank and the cold water inlet of the hot water generating means,
The control unit realizes the first circulation state by closing the third on-off valve and opening the first hot water supply valve, and opens the third on-off valve to operate the hot water generating means. The hot water supply system according to the ninth or tenth invention, wherein the second circulation state is realized.

  In a twelfth aspect of the invention, the circulation system includes a circulation tank provided in the middle of the hot water supply pipe, and the second predetermined place is a place upstream of the circulation tank of the hot water supply pipe. The hot water supply system according to any one of the first to eleventh inventions.

  A thirteenth aspect of the invention is the hot water supply system according to the twelfth aspect of the invention, wherein the hot water supply water temperature sensor is provided in the circulation tank.

  In a fourteenth aspect of the invention, any one of the first to thirteenth aspects, wherein the circulation tank is provided so that hot water flowing through the hot water supply pipe flows in from a lower portion thereof and flows out from an upper portion thereof. The hot water supply system described.

  A fifteenth aspect of the invention is the hot water supply system according to any one of the first to fourteenth aspects of the invention, wherein the hot water generating means is a heat pump using carbon dioxide as a refrigerant.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the thermal efficiency of the whole hot water supply system can be prevented, ensuring the capacity | capacitance of a hot water storage tank.

  FIG. 1 is an overall configuration diagram of a hot water supply system 1 according to an embodiment of the present invention. As shown in the figure, the hot water supply system 1 of the present embodiment mainly includes hot water generation means 10, hot water storage means 20, a circulation tank 30, a first circulation valve 54, a second circulation valve 55, a control unit 60, a pump 70, and the like. It is provided as a component.

The hot water generation means 10 is, for example, a heat pump using CO ₂ gas as a refrigerant, and heats cold water (for example, about 10 to 25 ° C.) at room temperature to obtain hot water (for example, about 90 ° C.). The hot water outlet of the hot water generating means 10 is connected to a downstream hot water storage tank 21 (“corresponding to a second hot water storage tank” in the claims) via a hot water storage pipe 61. A hot water storage valve 51 is provided in the hot water storage pipe 61. A water supply pipe 62 is connected to the cold water inlet of the hot water generating means 10. A water supply valve 56 is provided in the water supply pipe 62.

  The hot water storage means 20 includes a downstream hot water storage tank 21, an intermediate hot water storage section 22, and an upstream hot water storage tank 23 ("corresponding to the first hot water storage tank" in the claims), which are tanks connected in series. And the warm water produced | generated by the warm water production | generation means 10 is stored. The lowermost part of the downstream hot water storage tank 21 and the uppermost part of the intermediate hot water storage part 22 are connected by a first tank connection pipe 71, and the lowermost part of the intermediate hot water storage part 22 and the uppermost part of the upstream hot water storage tank 23 are connected to the second tank. The connection pipe 72 connects. The hot water generated by the hot water generating means 10 is first stored in the downstream hot water storage tank 21 from the uppermost portion via the hot water storage pipe 61. When the hot water is filled in the downstream hot water storage tank 21, the hot water is gradually filled into the intermediate hot water storage section 22 from its uppermost portion via the downstream hot water storage tank 21 and the first tank connection pipe 71. Further, when the hot water is filled in the intermediate hot water storage section 22, the hot water is filled into the upstream hot water storage tank 23 from the uppermost portion thereof via the downstream hot water storage tank 21, the intermediate hot water storage section 22 and the second tank connection pipe 72. Further, the downstream hot water storage tank 21 and the intermediate hot water storage section 22 are connected to the lower part of the circulation tank 30 through the hot water supply pipe 64 from the uppermost part thereof. Furthermore, a hot water supply pipe 65 for supplying hot water to the hot water outlet 40 of each dwelling unit is connected to the upper part of the circulation tank 30. The downstream hot water storage tank 21 is connected to the hot water supply pipe 64 via the downstream pipe 74, and the first hot water supply valve 52 is provided in the downstream pipe 74. The hot water storage pipe 61 is connected to the downstream hot water storage tank 21 via the downstream pipe 74. On the other hand, the intermediate hot water storage section 22 is connected to the hot water supply pipe 64 via the intermediate pipe 73, and the second hot water supply valve 58 is provided in the intermediate pipe 73.

  The upstream hot water storage tank 23 is connected to the water supply pipe 62 at the lowermost part of the upstream hot water storage tank 23, and a water supply valve 56 (on the side closer to the hot water generating means 10) downstream from this connection location (the claims) A range “equivalent to a“ third on-off valve ”” is installed. Further, a water supply branch pipe 63 leading to the hot water supply pipe 64 is branched on the upstream side (water supply side) from this connection point.

  In FIG. 1, three hot water storage tanks are shown, but any number of hot water storage tanks may be used as long as there are three or more hot water storage tanks. When there are four or more, the hot water storage tank directly connected to the hot water supply pipe 64 and located closest to the hot water outlet of the hot water generating means 10 is the first hot water storage tank, and is closest to the cold water inlet of the hot water generating means 10. The hot water storage tank positioned is the second hot water storage tank, and any one of the hot water storage tanks positioned therebetween corresponds to the intermediate hot water storage section.

  The first hot water storage hot water sensor 31 is provided at the uppermost part of the downstream hot water storage tank 21 and detects the uppermost water temperature of the downstream hot water storage tank 21 (hereinafter referred to as hot water storage water temperature T1). A signal indicating the circulating water temperature T <b> 1 detected by the hot water storage water temperature sensor 31 is supplied to the control unit 60.

  The second hot water storage hot water sensor 32 is provided at the uppermost portion of the intermediate hot water storage section 22 and detects the uppermost water temperature of the intermediate hot water storage section 22 (hereinafter referred to as hot water storage water temperature T2). A signal indicating the circulating water temperature T2 detected by the second hot water storage hot water sensor 32 is supplied to the control unit 60.

  Similarly, the upstream hot water sensor 33 is provided at the lowermost part of the upstream hot water storage tank 23 and detects the water temperature at the lowermost part of the upstream hot water storage tank 23 (hereinafter referred to as hot water storage water temperature T3). A signal indicating the circulating water temperature T3 detected by the third hot water storage hot water sensor 33 is supplied to the control unit 60.

  Further, a mixed hot water sensor 34 is provided downstream of the junction of hot water supplied from the downstream hot water storage tank 21 and the intermediate hot water storage section 22 and upstream of the mixing valve 53 described later. The temperature of the hot water mixed with the hot water supplied from the intermediate hot water storage unit 22 (hereinafter referred to as the hot water temperature T4) is detected. A signal indicating the circulating water temperature T4 detected by the mixed hot water sensor 34 is supplied to the controller 60.

  The hot water supply pipe 64 is provided with a mixing valve 53 that is a three-way valve, and a water supply branch pipe 63 is connected to the mixing valve 53. The mixing valve 53 has a function of mixing the hot water supplied from the downstream hot water storage tank 21 or the intermediate hot water storage unit 22 with the cold water supplied from the water supply branch pipe 63 at a mixing ratio controlled by the control unit 60. is doing. An on-off valve may be provided in the water supply branch pipe 63 instead of the mixing valve 53. The open / close valve and the first hot water supply valve 52 and the second hot water supply valve 58 can mix hot water and water at a mixing ratio controlled by the control unit 60.

  A hot water supply water temperature sensor 35 is provided at a downstream side of the hot water supply pipe 64 in the vicinity of the mixing valve 53. A signal indicating the temperature of hot water in the hot water supply pipe 64 (hereinafter referred to as hot water temperature T5) is supplied to the controller 60 by the hot water temperature sensor 35.

  A circulation pipe 66 is connected near the hot water supply port 40 of the hot water supply pipe 65. The circulation pipe 66 branches into a first branch pipe 67 connected to the lower part of the circulation tank 30 and a second branch pipe 68 connected to the hot water storage means 20. The first branch pipe 67 is provided with a first circulation valve 54 (corresponding to the “first on-off valve” in the claims), and the second branch pipe 68 is provided with a second circulation valve 55 (in the claims). "Corresponding to a" second on-off valve ") is provided. Further, the circulation pipe 66 is provided with a pump 70 such that the suction port is on the hot water supply pipe 65 side and the discharge port is on the first branch pipe 67 and the second branch pipe 68 side. The circulation pipe 66, the circulation tank 30, the first branch pipe 67, the second branch pipe 68, the first circulation valve 54, and the second circulation valve 55 described above correspond to the “circulation system” of the present invention. .

  The second branch pipe 68 is connected to the hot water generating means 10 via a third branch pipe 69 that further branches before the second circulation valve 55. Further, the third branch pipe 69 includes an opening / closing valve 57.

  The circulation tank 30 is provided with a hot water supply water temperature sensor 36 that detects the internal water temperature (hereinafter referred to as the circulation water temperature T6). A signal indicating the circulating water temperature T6 detected by the hot water supply water temperature sensor 36 is supplied to the control unit 60. The hot water temperature sensor 36 corresponds to a hot water temperature sensor referred to in the claims.

  The operation / stop of the hot water generating means 10 and the pump 70 is controlled by the control unit 60. The hot water storage valve 51, the first hot water supply valve 52, the second hot water supply valve 58, the first circulation valve 54, the second circulation valve 55, and the water supply valve 56 are all open / close valves. Controlled by Further, as described above, the operation of the mixing valve 53 that is a three-way valve is also controlled by the control unit 60.

  The hot water supply system 1 of the present embodiment stores the hot water heated by the hot water generating means 10 in each hot water storage tank 21 to 23 in the midnight time zone where the electricity bill is low and the amount of hot water used is small. The hot water stored in 23 is supplied to the hot water outlet 40 of each dwelling unit.

  First, the operation during hot water supply will be described. The controller 60 is in a time zone other than the midnight time zone, and the hot water temperature T2 is equal to or higher than a predetermined temperature Tx (for example, 75 ° C .; equivalent to “predetermined first temperature” in the claims). When the water temperature T4 is equal to or higher than a predetermined temperature Ty (<Tx; for example, 70 ° C.), as shown in FIG. 2, the hot water storage valve 51 and the water supply valve 56 are closed, the hot water supply valve 52 is opened, and hot water generating means 10 is stopped, and the mixing valve 53 is controlled based on the hot water temperature T5 so that the hot water temperature T5 becomes a predetermined temperature Th (for example, 65 ° C.). However, as will be described later, when the hot water in the circulation pipe 66 is circulated to the first tank connection pipe 71, this control is not performed (that is, the water supply branch pipe 63 side is fully closed, and the downstream hot water storage tank is 21 or the hot water in the intermediate hot water storage section 22 is supplied to the hot water supply pipe 65 as it is without being mixed with cold water). When the hot water supply port 40 is opened, hot water discharged from the downstream hot water storage tank 21 is mixed with cold water by the mixing valve 53 to reach the predetermined temperature Th, and then supplied to the hot water supply port 40. The user of each dwelling unit adjusts the hot water supply temperature to a desired temperature by operating a mixing plug (not shown) provided in the hot water supply port 40 to mix cold water.

  When hot water is discharged from the downstream hot water storage tank 21 in this way, an equal amount of cold water flows from the lowermost part of the upstream hot water storage tank 23 via the water supply pipe 62, and the hot water stored in the upstream hot water storage tank 23 is discharged. The hot water pushed out to the intermediate hot water storage unit 22 and further stored in the intermediate hot water storage unit 22 is pushed out to the downstream hot water storage tank 21. Therefore, in each of the hot water storage tanks 21 to 23, cold water is stored in the lower part of the upstream hot water storage tank 23, and hot water is stored in the downstream hot water storage tank 21 and the intermediate hot water storage unit 22, respectively. The hot water and cold water in the hot water storage tank are separated into a hot water layer and a cold water layer due to the difference in specific gravity. Mixing of warm water and cold water occurs, and the medium temperature mixed water layer gradually expands.

  If the hot water supply is continued in this way, the cold water gradually pushes up the hot water from the vicinity of the water supply port of the upstream hot water storage tank 23, and the upstream hot water storage tank 23 is filled with cold water. Further, when the upstream hot water storage tank 23 is filled with cold water, cold water flows into the intermediate hot water storage section 22 from the lowermost portion thereof via the second tank connection pipe 72.

  Now, cold water flows into the intermediate hot water storage section 22, and the intermediate temperature mixed layer expands in the intermediate hot water storage section 22. As a result, the stored hot water temperature T2 is lower than the predetermined temperature Tx and the predetermined temperature Ty (<Tx; for example, 70 ° C .; patent If it is equal to or higher than the “predetermined second temperature” in the claims, the hot water in the intermediate hot water storage section 22 is supplied to the hot water supply port 40 as shown in FIG. In this case, a medium temperature mixed layer generated in the intermediate hot water storage section 22 is used for hot water supply. Specifically, the hot water storage valve 51, the water supply valve 56 and the first hot water supply valve 52 are closed, the second hot water supply valve 58 is opened and the operation of the hot water generating means 10 is stopped, and based on the hot water supply water temperature T5, The mixing valve 53 is controlled so that the hot water temperature T5 becomes a predetermined temperature Th.

  The stored hot water temperature T2 is equal to or higher than a predetermined temperature Tx (for example, 75 ° C .; corresponding to “predetermined first temperature” in the claims), but the stored hot water temperature T4 is a predetermined temperature Ty (<Tx; for example, 70 ° C.). When the temperature is less than), the hot water of the intermediate hot water storage section 22 is supplied to the hot water supply port 40 as shown in FIG.

  The amount of cold water flowing into the intermediate hot water storage section 22 is increased and the mixed layer is expanded. As a result, the hot water temperature T2 is lower than the predetermined temperature Ty and the predetermined temperature Tz (<Ty; for example, 25 ° C .; If it is equal to or higher than “predetermined third temperature”, the hot water in the downstream hot water storage tank 21 and the hot water in the intermediate hot water storage unit 22 are mixed and supplied to the hot water supply port 40 as shown in FIG. This uses the mixed layer generated in the intermediate hot water storage section 22 for hot water supply, but since the water temperature of the mixed layer is low, the required hot water temperature in the downstream hot water storage tank 21 is mixed to ensure the necessary water temperature. . Specifically, the hot water storage valve 51 and the water supply valve 56 are closed, the first hot water supply valve 52 and the second hot water supply valve 58 are opened to stop the operation of the hot water generating means 10, and based on the hot water supply water temperature T4, The first hot water supply valve 52 and the second hot water supply valve 58 are controlled so that the hot water temperature T4 becomes a predetermined temperature Th.

  Further, as a result of the intermediate hot water storage unit 22 being filled with cold water, when the hot water temperature T2 becomes lower than the predetermined temperature Tz, hot water in the downstream hot water storage tank 21 is supplied to the hot water supply port 40 as shown in FIG. This is because only the hot water in the downstream hot water storage tank 21 is used because the water in the intermediate hot water storage section 22 cannot be used because the water temperature is low. Specifically, the hot water storage valve 51, the water supply valve 56, and the second hot water supply valve 58 are closed, the operation of the hot water generating means 10 is stopped as the first hot water supply valve 52, and the hot water supply water temperature is based on the hot water supply water temperature T5. The mixing valve 53 is controlled so that T5 becomes the predetermined temperature Th.

  As described above, there are three types of hot water supply: hot water in the downstream hot water storage tank 21, hot water in the intermediate hot water storage unit 22, and hot water in the downstream hot water storage tank 21 and the intermediate hot water storage unit 22. FIG. 5 summarizes the processing in a flowchart. First, if the hot water storage water temperature T2 at the top of the intermediate hot water storage section 22 is equal to or higher than the predetermined temperature Tx (S502: YES) and the hot water storage water temperature T4 is equal to or higher than the predetermined temperature Ty (S504: YES), the first hot water supply valve 52 is turned on. Hot water is supplied from the downstream hot water storage tank 21 by closing the second hot water supply valve 58 in the open state (S506). Next, even if the hot water temperature T2 is lower than the predetermined temperature Tx (S502: NO), if it is equal to or higher than Ty (S508: YES), the first hot water supply valve 52 is closed and the second hot water supply valve 58 is opened. Thus, hot water is supplied from the intermediate hot water storage section 22 (S510). Further, if the hot water storage water temperature T2 is equal to or higher than the predetermined temperature Tx (S502: YES) and the hot water storage water temperature T4 is lower than the predetermined temperature Ty (S504: NO), the first hot water supply valve 52 is closed and the second hot water supply valve 58 is closed. Is opened, hot water is supplied from the intermediate hot water storage section 22 (S510). Even if the hot water temperature T2 is lower than the predetermined temperature Ty (S508: NO), if it is equal to or higher than Tz (S512: YES), the first hot water supply valve 52 is opened and the second hot water supply valve 58 is also open. By doing so, the hot water of both the downstream hot water storage tank 21 and the intermediate hot water storage part 22 is mixed and hot water is supplied (S514). Furthermore, when the hot water storage water temperature T2 is lower than the predetermined temperature Tz (S512: NO), hot water is supplied from the downstream hot water storage tank 21 by opening the first hot water supply valve 52 and closing the second hot water supply valve 58. (S516).

  Next, operation during hot water storage will be described. In the midnight time zone, as shown in FIG. 6, the control unit 60 opens the hot water storage valve 51, the water supply valve 56, and the first hot water supply valve 52, and operates the hot water generation means 10. As a result, cold water is supplied to the hot water generating means 10 from the lowermost part of the upstream hot water storage tank 23 to be heated and flows into the uppermost part of the downstream hot water storage tank 21 via the hot water storage pipe 61.

  Then, first, the downstream hot water storage tank 21 flows in from the upper part with high-temperature hot water supplied from the hot water generating means 10. When the hot water reaches the lowermost part of the downstream hot water storage tank 21, the hot water then flows from the uppermost part of the intermediate hot water storage part 22 through the first tank connection pipe 71. Similarly, when the hot water reaches the lowermost part of the intermediate hot water storage unit 22, the hot water then flows from the uppermost part of the upstream hot water storage tank 23 through the second tank connection pipe 72. An upstream water temperature sensor 33 is provided at the lowermost part of the upstream hot water storage tank 23, and the control unit 60 has a predetermined high temperature (for example, 90 ° C.) in the upstream hot water storage tank 23 based on the water temperature T 3 detected by the upstream water temperature sensor 33. When it is detected that the hot water reaches the lowermost part, the hot water generating means 10 is stopped and the hot water storage valve 51 and the water supply valve 56 are closed. In addition, when hot water supply port 40 is opened and hot water is supplied during hot water storage at midnight, hot water from hot water generating means 10 is supplied directly to hot water supply pipe 64.

  Regardless of the time zone, the control unit 60 operates the pump 70, and based on the circulating water temperature T6, the hot water in the hot water supply pipe 65 is supplied to the circulation tank 30 via the first branch pipe 67 or the second branch pipe. It is circulated to the downstream hot water storage tank 21 or the intermediate hot water storage section 22 through 68. Hereinafter, the operation of the circulation system will be described.

  First, when the circulating water temperature T6 is equal to or higher than a fourth predetermined temperature Ta (for example, 55 ° C.), the first circulation valve 54 is opened and the second circulation valve 55 is closed as shown in FIG. Accordingly, the hot water in the hot water supply pipe 65 is circulated to the circulation tank 30 through the circulation pipe 66 and the first branch pipe 67. At that time, since the amount of hot water circulated by the circulation tank 30 is increased, the hot water is difficult to cool, but since there is no heat supply from the outside, the water temperature gradually decreases. In this case, at least one of the first hot water supply valve 52 and the second hot water supply valve 58 is always in an open state so that hot water can be supplied as soon as use of hot water is started at the hot water supply port 40.

  When the circulating water temperature T6 becomes lower than the fourth predetermined temperature Ta, the control unit 60 closes the first circulation valve 54 and opens the second circulation valve 55 as shown in FIG. The control of the mixing valve 53 based on the hot water supply temperature T5 described above is stopped and the water supply branch pipe 63 side is fully closed so that the cold water is not mixed with the hot water in the hot water storage tank 21 on the downstream side of the hot water storage means 20. Thereby, the hot water in the hot water supply pipe 65 is returned to the downstream hot water storage tank 21 through the circulation pipe 66 and the second branch pipe 68, and the hot hot water in the downstream hot water storage tank 21 is circulated through the hot water supply pipe 64. 30. At that time, since the high-temperature hot water is supplied to the circulation tank 30 from the lower part, the warm water in the circulation tank 30 is stirred by natural convection, and the internal water temperature becomes substantially uniform.

  When the hot water in the downstream hot water storage tank 21 is supplied to the circulation tank 30 in this way, the circulating water temperature T6 rises, and when the fifth predetermined temperature Tb (> Ta; for example, 65 ° C.) is reached, the control unit 60 displays the temperature again. As shown in FIG. 2, the first circulation valve 54 is opened, the second circulation valve 55 is closed, and the control of the mixing valve 53 based on the hot water temperature T5 is resumed.

  However, when the hot water of the circulation system is supplied to the upstream hot water storage tank 21, the internal water temperature gradually decreases, and when the hot water temperature T3 becomes lower than a sixth predetermined temperature Tc (for example, 65 ° C.), the upstream hot water storage tank 21. Depending on the hot water, the circulating water temperature T6 cannot be raised sufficiently.

  In this case, as shown in FIG. 9, the control unit 60 closes the first circulation valve 54, opens the second circulation valve 55 and the water supply valve 56, and mixes the mixing valve based on the hot water supply temperature T1 described above. 53 is stopped and the state where the water supply branch pipe 63 side is fully closed is maintained. Thereby, the hot water in the hot water supply pipe 65 is returned to the intermediate hot water storage section 22 through the circulation pipe 66 and the second branch pipe 68. As a result, the cold water stored in the upstream hot water storage tank 23 is pushed out and supplied to the cold water inlet of the hot water generating means 10 and heated by the hot water generating means 10 to become hot hot water via the hot water storage pipe 61 and the hot water supply pipe 64. And supplied to the circulation tank 30. Since the control of the mixing valve 53 is stopped and the water supply branch pipe 63 side is fully closed, the cold water is not mixed with the high-temperature hot water generated by the hot water generating means 10. At this time, since hot water is supplied to the circulation tank 30 from below, the warm water in the circulation tank 30 is agitated by natural convection, and the water temperature inside becomes substantially uniform.

  Also in this case, at least one of the first hot water supply valve 52 and the second hot water supply valve 58 is always in an open state so that hot water can be supplied immediately after the use of hot water at the hot water supply port 40 is started. Regarding the circulating hot water, the amount discharged from the pump 70 and the amount sucked into the hot water generating means 10 are substantially the same, and the amount discharged from the hot water generating means 10 and the amount sucked into the pump 70 Are almost the same amount, so even if the first hot water supply valve 52 is open, the hot water hardly flows into the downstream hot water storage tank 21.

  By supplying the hot water generated by the hot water generating means 10 to the circulation tank 30 in this way, the circulating water temperature T6 rises, and when the fifth predetermined temperature Tb is reached, the control unit 60 again returns as shown in FIG. The first circulation valve 54 is opened, the second circulation valve 55 is closed, and the control of the mixing valve 53 based on the hot water temperature T5 is resumed.

  The hot water in the downstream hot water storage tank 21 is lower than the predetermined temperature Tc, but when the hot water at the predetermined temperature (for example, 60 ° C.) or higher is stored in the upstream hot water storage tank 23, Since heating reduces thermal efficiency, the hot water of the circulation system may be heated by the hot water generating means 10 as usual. That is, the on-off valve 57 may be opened, and the hot water of the circulation system may be supplied to the hot water generating means 10 through the third branch pipe 69 and heated there to be returned to the circulation system again. In other cases, the on-off valve 57 is closed.

  By the way, in order to establish the circulation of the hot water as described above, the hot water storage means 20 stores hot water of high temperature (for example, about 85 ° C.), and the circulation tank 30 has an intermediate temperature that is the temperature of the hot water supplied to the hot water supply port 40. It is assumed that hot water (for example, about 65 ° C.) is stored.

  FIG. 10 summarizes the control processing described above in a flowchart. First, if the circulating water temperature T2 exceeds the temperature Ta (S1002: YES), the first circulating valve 54 is opened and the second circulating valve 55 is closed (S1004). A state of circulating to the circulation tank 30 through the one branch pipe 67 is assumed (FIG. 7).

  If the circulating water temperature T2 is equal to or lower than the temperature Ta (S1002: NO), the first circulating valve 54 is closed and the second circulating valve 55 is opened (S1006). It is sent to the hot water storage means 20 via the second branch pipe 68. Further, if the hot water storage water temperature T3 exceeds Tc (S1008: YES), the hot water supply valve 52 is opened (S1010), and the hot water in the hot water supply pipe 65 passes to the downstream hot water storage tank 21 via the circulation pipe 66 and the second branch pipe 68. It is set as the state (FIG. 8) which is returned and the hot hot water of the downstream hot water storage tank 21 is supplied to the circulation tank 30 via the hot water supply piping 64. In this case, the control of the mixing valve 53 based on the hot water supply temperature T1 is stopped and the water supply branch pipe 63 side is fully closed so that the cold water is not mixed with the hot water in the hot water storage tank 21 on the downstream side of the hot water storage means 20. (S1010).

  On the other hand, when the hot water in the hot water supply pipe 65 is being sent to the hot water storage means 20 (S1006) and the hot water temperature T3 is equal to or lower than Tc (S1008: NO), the hot water storage valve 51 and the water supply valve 56 are opened. By operating the generating means 10 (S1014), the hot water in the hot water supply pipe 65 is returned to the intermediate hot water storage section 22 through the circulation pipe 66 and the second branch pipe 68, and further stored in the upstream hot water storage tank 23. The cold water being extruded is supplied to the hot water generating means 10, heated here to become hot hot water, and is supplied to the circulation tank 30 via the hot water storage pipe 61 and the hot water supply pipe 64 (FIG. 9). In this case, the control of the mixing valve 53 based on the hot water supply temperature T1 is stopped and the water supply branch pipe 63 side is fully closed so that the cold water is not mixed with the hot water in the hot water storage tank 21 on the downstream side of the hot water storage means 20. (S1014).

  Further, even after the process of S1010 or S1014, if the circulating water temperature T2 is equal to or lower than Tb (S1012: NO), the process returns to S1008. On the other hand, if the circulating water temperature T2 exceeds Tb (S1012: YES), the process proceeds to S1004, and the hot water in the hot water supply pipe 65 is circulated to the circulation tank 30 via the circulation pipe 66 and the first branch pipe 67 (FIG. 7). ).

  Thus, in the present embodiment, during hot water storage, the mixed water generated by mixing hot water and water in the hot water storage tank is used for hot water supply, thereby ensuring the capacity of the hot water storage tank and improving the thermal efficiency of the entire hot water supply system. A decrease can be prevented. That is, in the hot water supply system 1, three or more hot water storage tanks are provided and these are arranged in series, and a medium temperature mixed water obtained by mixing hot water and cold water generated in a hot water storage tank located in the middle due to repetition of hot water supply or hot water storage, By taking out from the hot water storage tank located in the middle and mixing it with hot water of high temperature in another hot water storage tank and using it for hot water supply, the expansion of the mixed water layer can be suppressed. Conventionally, the mixed water cannot be used for hot water supply or reheating, and when this mixed water layer is expanded, the substantial capacity of the hot water storage tank is reduced. Since water can be used effectively, it is possible to prevent a decrease in the thermal efficiency of the entire hot water supply system while securing the capacity of the hot water storage tank.

  In the present embodiment, when the circulating water temperature T6 falls below the fourth predetermined temperature Ta while the hot water in the hot water supply pipe 65 is circulated through the circulation tank 30, the circulating water temperature T6 becomes the fifth predetermined temperature Tb. The circulating water temperature T6 can be maintained between the fourth predetermined temperature Ta and the second predetermined temperature Tb by circulating the hot water in the hot water supply pipe 65 through the downstream hot water storage tank 21 until the temperature reaches the predetermined temperature Tb. Furthermore, even when the hot water temperature in the downstream hot water storage tank 21 is lowered, the cold water in the upstream hot water storage tank 23 is heated by the hot water generating means 10 to circulate the hot water having a high temperature, thereby circulating water temperature. T6 can be maintained between the fourth predetermined temperature Ta and the second predetermined temperature Tb. Thus, even when the amount of hot water supplied from the hot water supply port 40 is small, such as at midnight, and the hot water in the hot water supply pipes 64 and 65 is easy to cool, hot water at a desired temperature is immediately supplied when the hot water supply port 40 is opened. It becomes possible to do.

  Then, the hot water in the circulation pipe 66 is not directly heated by the hot water generating means 10 that is a heat pump as in the prior art described in Patent Document 1, but is first circulated through the downstream hot water storage tank 21. Therefore, the hot water in the circulation pipe 66 can be efficiently heated without causing a decrease in thermal efficiency due to heating of the circulating hot water that has not been cooled by the heat pump, and the thermal efficiency of the entire system is improved.

  Furthermore, when the hot water in the circulation tank is cooled by the heat pump as in the above prior art, the hot water in the circulation tank is discharged from the lower part and supplied to the heat pump, and the hot water heated by the heat pump is It becomes the structure supplied from the upper part of a circulation tank. For this reason, in order to make the water temperature in the circulation tank uniform, means for stirring the inside of the circulation tank by, for example, forcibly supplying hot water from the lower pipe to the upper pipe of the circulation tank is required. On the other hand, in the present embodiment, as described above, the hot water in the downstream hot water storage tank 21 or the hot water generated by the hot water generating means 10 is supplied to the circulating tank 30 from the lower part thereof, thereby the inside of the circulating tank 30. Of hot water is stirred by natural convection. For this reason, it is not necessary to separately provide a means for stirring the inside of the circulation tank 30, and the cost can be reduced accordingly.

  In addition, the description of the above embodiment is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

1 is an overall configuration diagram of a hot water supply system 1 according to an embodiment of the present invention. It is a figure which shows an example of the hot water supply of the hot water in the hot water supply system 1 which is embodiment of this invention. It is a figure which shows another example of the hot water supply of the hot water in the hot water supply system 1 which is embodiment of this invention. It is a figure which shows another example of the hot water supply of the hot water in the hot water supply system 1 which is embodiment of this invention. It is a flowchart which concerns on the hot water storage tank selection in the hot water supply in the hot water supply system 1 which is embodiment of this invention. It is a figure which shows an example of the hot water storage in the hot water supply system which is embodiment of this invention. It is a figure which shows an example of the circulation of the warm water in the hot water supply system 1 which is embodiment of this invention. It is a figure which shows another example of the circulation of the warm water in the hot water supply system 1 which is embodiment of this invention. It is a figure which shows another example of the circulation of the warm water in the hot water supply system 1 which is embodiment of this invention. It is a flowchart which concerns on the circulation path selection in the circulation of the warm water in the hot water supply system 1 which is embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot water supply system 10 Hot water production | generation means 20 Hot water storage means 21 Downstream hot water storage tank 22 Intermediate hot water storage part 23 Upstream hot water storage tank 30 Circulation tank 31 Hot water storage water temperature sensor 32 Intermediate water temperature sensor 33 Upstream water temperature sensor 34 Mixed water temperature sensor 35, 36 Hot water supply water temperature sensor 40 Hot water supply port 51 Hot water storage valve 52 First hot water supply valve 53 Mixing valve 54 First circulation valve 55 Second circulation valve 56 Water supply valve 57 On-off valve 58 Second hot water supply valve 60 Controller 61 Hot water storage pipe 62 Water supply pipe 63 Water supply branch pipe 64, 65 Hot water supply pipe 66 Circulating pipe 67 First branch pipe 68 Second branch pipe 69 Third branch pipe 70 Pump 71 First tank connection pipe 72 Second tank connection pipe 73 Intermediate pipe 74 Downstream pipe

Claims (16)

Hot water generating means for generating hot water;
Hot water storage means for storing hot water generated by the hot water generation means;
A hot water supply pipe for supplying hot water stored in the hot water storage means,
The hot water storage means includes a first hot water storage tank directly connected to a cold water inlet of the hot water generating means, a second hot water storage tank directly connected to the hot water supply pipe, the first hot water storage tank, and the second hot water storage tank. An intermediate hot water storage unit composed of one or more intermediate hot water storage tanks connected in series with the hot water storage tank,
The hot water storage system further includes:
An intermediate pipe for supplying hot water stored in the intermediate hot water storage section to the hot water supply pipe;
An intermediate water temperature sensor for detecting the water temperature of the intermediate hot water storage unit;
Based on the water temperature detected by the intermediate water temperature sensor, a first hot water supply state in which hot water in the second hot water storage tank is supplied to the hot water storage pipe, hot water in the intermediate hot water storage section is supplied to the hot water supply pipe through the intermediate pipe. And a controller that selectively realizes a second hot water supply state or a third hot water supply state in which hot water from both the second hot water storage tank and the intermediate hot water storage portion is supplied to the hot water supply pipe. Hot water supply system. A first hot water supply valve installed at a location connected to the hot water supply pipe from the second hot water storage tank;
A second hot water valve installed in the intermediate pipe;
With
The control unit controls the amount of hot water supplied from the second hot water storage tank and the intermediate hot water supply unit to the hot water supply pipe by adjusting the opening of the first hot water supply valve and the second hot water supply valve. The hot water supply system according to claim 1.   When the water temperature detected by the intermediate water temperature sensor is equal to or higher than a predetermined first water temperature or lower than a predetermined second water temperature lower than the first water temperature, the control unit sets the first hot water supply state. It implement | achieves, The hot water supply system of Claim 1 or 2 characterized by the above-mentioned.   When the water temperature detected by the intermediate water temperature sensor is less than a predetermined first water temperature and is equal to or higher than a predetermined third water temperature lower than the first water temperature and higher than the second water temperature, The hot water supply system according to any one of claims 1 to 3, wherein the second hot water supply state is realized.   The said control part implement | achieves the said 3rd hot water supply state, when the water temperature which the said intermediate water temperature sensor detects is less than the said 3rd water temperature, and is more than the said 2nd water temperature. The hot water supply system in any one of -4. A hot water temperature sensor for detecting the temperature of hot water in the hot water supply pipe;
A circulation system for selectively connecting the first predetermined location of the hot water supply pipe to the second predetermined location upstream of the first predetermined location of the hot water supply pipe or the hot water storage means;
Based on the water temperature detected by the hot water temperature sensor, a control unit that switches the connection destination of the first predetermined location by the circulation system to the second predetermined location or the hot water storage means;
The hot water supply system according to any one of claims 1 to 5, further comprising: The controller is
When the water temperature detected by the hot water temperature sensor is equal to or higher than a fourth predetermined temperature, the connection destination of the first predetermined location is the second predetermined location,
When the water temperature detected by the hot water temperature sensor is lower than the fourth predetermined temperature, the connection destination of the first predetermined location by the circulation system is the hot water storage means, and then the water temperature is the fourth temperature. The hot water supply system according to claim 6, wherein when a predetermined upper limit temperature higher than a predetermined temperature is reached, a connection destination of the first predetermined location by the circulation system is set as the second predetermined location. The circulation system branches into a first branch pipe connected to the second predetermined location and a second branch pipe connected to the hot water storage means,
A first on-off valve is provided in the first branch pipe;
A second on-off valve is provided in the second branch pipe;
The controller is
By opening the first on-off valve and closing the second on-off valve, the connection destination of the first predetermined location by the circulation system is the second predetermined location,
8. The hot water storage means is the connection destination of the first predetermined location by the circulation system by closing the first on-off valve and opening the second on-off valve. Hot water system. It has a hot water storage water temperature sensor that detects the water temperature of the first hot water storage tank,
The control unit supplies hot water stored in the second hot water storage tank to the hot water supply pipe based on the water temperature detected by the hot water storage water temperature sensor when the connection destination of the circulation system is the hot water storage means. The first circulating state to be switched and the second circulating state to be supplied to the cold water inlet of the hot water generating means by the cold water in the first hot water storage tank being pushed out by the hot water from the circulation system The hot water supply system according to any one of claims 6 to 8. The controller is
In the case where the connection destination of the first predetermined location by the circulation system is the hot water storage means, and the hot water storage water temperature sensor exceeds the fifth predetermined temperature, switching to the first circulation state,
In the case where the connection destination of the first predetermined place by the circulation system is the hot water storage means, and when the hot water temperature sensor falls below a fifth predetermined temperature, the hot water storage temperature switch is switched to the second circulation state. The hot water supply system according to claim 9. A pipe that connects the first hot water storage tank and the cold water inlet of the hot water generating means is provided with a third on-off valve,
The control unit realizes the first circulation state by closing the third on-off valve and opening the first hot water supply valve, and opens the third on-off valve to operate the hot water generating means. The hot water supply system according to claim 9 or 10, wherein the second circulation state is realized.   The said circulation system is provided with the circulation tank provided in the middle of the said hot water supply pipe, The said 2nd predetermined location is a location of the upstream of the said circulation tank of the said hot water supply piping, It is characterized by the above-mentioned. The hot water supply system in any one of -11.   The hot water supply system according to claim 12, wherein the hot water supply temperature sensor is provided in the circulation tank.   The hot water supply system according to any one of claims 1 to 13, wherein the circulation tank is provided so that hot water flowing through the hot water supply pipe flows in from a lower part thereof and flows out from an upper part thereof.   The hot water supply system according to any one of claims 1 to 14, wherein the hot water generating means is a heat pump using carbon dioxide as a refrigerant. Generating warm water;
Between the first hot water storage tank directly connected to the cold water inlet of the hot water generating means, the second hot water storage tank directly connected to the hot water supply pipe, and between the first hot water storage tank and the second hot water storage tank Storing the generated hot water in a hot water storage means constituted by an intermediate hot water storage section comprising one or more intermediate hot water storage tanks connected in series to
Supplying hot water stored in the hot water storage means via a hot water supply pipe;
Supplying hot water stored in the intermediate hot water storage section to the hot water storage pipe through an intermediate pipe;
Detecting the water temperature of the intermediate hot water storage section with an intermediate water temperature sensor;
Based on the water temperature detected by the intermediate water temperature sensor, a first hot water supply state in which hot water in the second hot water storage tank is supplied to the hot water storage pipe, hot water in the intermediate hot water storage section is supplied to the hot water supply pipe through the intermediate pipe. Selectively realizing a second hot water supply state, or a third hot water supply state in which hot water of both the first hot water storage tank and the intermediate hot water storage unit is supplied to the hot water supply pipe,
A hot water supply system characterized by including.

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