JP2003185271A - Water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water supply direct pressure type regenerative water heater for exchanging heat without driving a pump means with a heat storage fluid in a tank. Reduce costs. SOLUTION: A heat exchange pipe line 25 having a tank 22 for storing a heat storage fluid W, which is directly connected to a water supply and has an outlet 27 at an upper portion of the tank 22, is provided in the tank 22. When the hot water is used, the hot water from the water supply flows through the heat exchange pipe 25, the heat storage fluid W exchanges heat with the hot water by natural convection, and the hot water is supplied by the tap water direct pressure type. Can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage type water heater.

[0002]

2. Description of the Related Art Heretofore, as a water heater of this type, there has been a water heater as described in JP 2001-153458 A, for example. FIG. 4 shows the conventional water heater described in the above publication. In the hot water supply device 1, a hot water supply heat exchanger 3 is arranged inside a tank 2 that stores a heat storage fluid. The hot water supply heat exchanger 3 has a primary passage 3a through which the heat storage fluid pumped by the electric pump 4 flows.
And an inner pipe having a secondary passage 3b connected to the hot water supply pipes (water supply pipe 5 and hot water supply pipe 6), and forming the secondary passage 3b inside the outer pipe forming the primary passage 3a. It is a double-tube structure that is inserted. This heat exchanger 3 for hot water supply is a tank 2
Of the heat storage fluid, which are arranged vertically in the interior of the secondary passage 3a and flow downward in the primary passage 3a, and flow downward in the secondary passage 3b. It is configured as a counterflow type. Reference numeral 7 is a heat storage fluid heating device, 8 is a heating pump, 9 is an inflow pipe, and 10 is an outflow pipe. In this configuration, the heating pump 8 is driven, the heat storage fluid is taken out of the tank 2, heated by the heating device 7, and returned to the tank 2 to store heat in the heat storage fluid. Then, the heat storage fluid pressure-fed to the primary side passage 3a while the flow rate is controlled by the electric pump 4 and the hot water for hot water flowing through the water supply pipe 5 are heat-exchanged by the counter flow hot water heat exchanger 3, The hot water for hot water supply is heated and discharged from the hot water supply pipe 6.

[0003]

However, in the conventional water heater, since the electric pump 4 is always driven while hot water is supplied, the utility cost of hot water supply is increased due to the power consumption during hot water supply. I can't save. In particular, even if a tank is provided to use the late-night electric power, which is cheaper, as a heat storage type water heater, the electric pump 4 is driven during a time period other than midnight when hot water supply is concentrated, so There was a problem in that electricity that was several times more expensive would be consumed, and the utility bill for hot water supply would increase.

The present invention is intended to solve the above-mentioned conventional problems. When the hot water is supplied, the heat storage fluid and the hot water for hot water exchange heat without driving the electric pump, and the electric power for driving the electric pump during the daytime is not required. It is an object of the present invention to provide a water heater having a large effect of saving the utility bill for hot water supply.

[0005]

In order to solve the above-mentioned problems, the water heater of the present invention comprises a tank for storing a heat storage fluid, the inlet side of which is directly connected to the tap water and the outlet of which is located above the tank. A heat exchange pipe is provided in the tank, and tap water for hot water supply flowing through the heat exchange pipe is heat-exchanged with the heat storage fluid to be heated and used for hot water supply.

As a result, the heat storage fluid stored in the high temperature in the upper part of the tank moves to the lower part of the tank due to the temperature drop due to the heat exchange from the vicinity of the outlet of the heat exchange pipe to the lower part, and does not contribute to the heat exchange and remains at the high temperature. The phenomenon that the heat storage fluid moves upward due to the difference in specific gravity is repeated. In this way
The heat storage fluid exchanges heat with the hot water for hot water supply by natural convection, and the heat exchanging does not require the driving of the pump means.

[0007]

The invention according to claim 1 is a tank having a tank for storing a heat storage fluid, a heating means for heating the heat storage fluid, an inlet side directly connected to water, and an outlet at the upper part of the tank. Since the hot water supply water is provided inside the heat exchange pipe for exchanging heat with the heat storage fluid, and the tap water heated by the heat exchange in the heat exchange pipe is supplied, the hot water is supplied directly from the water supply. The hot water is discharged by pressure, and the heat storage fluid exchanges heat with the water for hot water supply by natural convection.The heat exchange fluid and the water for hot water supply do not require the drive of an electric pump, so the electric pump drive power for hot water supply is unnecessary. It is possible to reduce the utility cost for hot water supply.

The invention as defined in claim 2 is particularly defined by claim 1.
By providing the inlet of the heat exchange pipe to the tank in the lower part of the tank, heat exchange is promoted from the lower part of the tank, so that the temperature of the heat storage fluid in the entire tank decreases due to heat dissipation by using hot water. , It prevents the hot water supply from becoming impossible below the high temperature required for the next hot water supply, and the upper part of the tank is kept relatively hot and the lower part comes close to the water supply temperature, so the heat storage fluid is reheated to a high temperature. The amount of heat in the tank can be efficiently used for hot water supply without being changed, and the utility cost for hot water supply can be reduced.

The invention described in claim 3 is particularly defined by claims 1 to 3.
In the invention of 2, the heat storage fluid is taken out from the lower part of the tank, is supplied to the heating means, and the heat storage fluid heated by the heating means is returned to the upper part of the tank. In the process of heating the inside of the tank to store heat from the state where the working fluid radiates heat and the inside of the tank is cooled,
By taking out the heat storage fluid from the lower part of the tank, heating it with heating means and returning it to the upper part of the tank, it is possible to form a temperature stratification in the tank, which is divided into a high temperature upper layer and a low temperature lower layer. Even if the amount of hot water used exceeds the amount used and the heat in the tank is exhausted, so-called hot water runs out, it is possible to raise the required temperature from the top without heating or raising the temperature in the entire tank. Energy can be saved, and utility costs for hot water supply can be reduced.

The invention as defined in claim 4 is particularly defined by claims 1 to 1.
By using the water heater described in 3 as a night-time heat storage type water heater that operates the heating means so as to store the amount of heat of the hot water supplied to the heat storage fluid in the tank at midnight using the late-night electricity rate system, Even when using hot water during the daytime, the drive power for a general electric pump is not required as a pumping means, and it is possible to cover the power required for hot water supply only with the late-night power. It can be reduced.

The invention as defined in claim 5 is particularly defined by claims 1 to 3.
In the heat pump cycle, the heating means described in 4 is a heat pump unit having a compressor, a radiator, a pressure reducing means, and an atmospheric heat exchanger that is an evaporator.
The coefficient of performance (COP = heating capacity / power consumption) can be operated with at least 1 or more, and depending on the conditions, the coefficient of performance can be about 3, so the electric power required to heat the heat storage fluid is when using an electric heater. It can be reduced to ⅓, and a significant saving of utility costs can be realized. In addition, the temperature of the heat storage fluid for hot water supply (for example, 65 to 90 ° C)
In the case of heating up to the heat pump cycle, the higher the pressure of the heat storage fluid, the lower the temperature of the heat storage fluid before heating, so the coefficient of performance improves. Therefore, the coefficient of performance is further improved by heating the heat storage fluid stored in the lower part of the tank to a temperature near the temperature of the tap water for hot water supply and stored in the lower part of the tank, further reducing power consumption and reducing utility costs. Can be achieved.

The invention according to claim 6 particularly claims 1 to
In the invention described in claim 5, the heat exchange pipe is provided substantially parallel to the tank wall surface from the inlet of the lower part of the tank to the outlet of the upper part thereof, and a diffusion preventing means is provided on the side of the heat exchange pipe opposite to the tank wall surface to dissipate heat. By preventing the heat storage fluid from diffusing and dividing the inside of the tank into a heat exchange area and a heat storage area, the diffusion preventing means promotes heat exchange only in the heat exchange area near the heat exchange pipe. It is possible to prevent the entire temperature from being uniformly lowered, to maintain the temperature stratification in the heat storage region in the tank, to improve the utilization efficiency of hot water in the tank for supplying hot water, and to reduce the utility cost for supplying hot water.

According to a seventh aspect of the present invention, particularly in the sixth aspect of the invention, a diffusion prevention plate having both upper and lower portions opened so that the heat exchange area and the heat storage area communicate with each other is provided. By changing the opening area of at least one of the upper opening and the lower opening, the opening area is changed so that convection flows from the upper opening to the lower opening through the heat exchange area in the tank. Since the flow resistance of the heat storage fluid can be changed, the flow rate of natural circulation in the heat exchange area is controlled, and the temperature of the heat storage fluid flowing into the heat storage area through the lower opening after heat exchange is adjusted to the hot water supply temperature before heating. Can be reduced to near the temperature. As a result, the temperature stratification of the heat storage region in the tank can be maintained and the temperature difference between the upper and lower sides can be increased, the efficiency of hot water supply in the tank can be improved, and the utility cost for hot water supply can be reduced.

According to an eighth aspect of the present invention, particularly in the seventh aspect, the control means having a target temperature set higher than the hot water supply temperature and the temperature of the hot water for hot water flowing out from the heat exchange pipe are detected. The temperature detecting means and the mixing means for mixing the heated hot water flowing out from the heat exchange pipe with the unheated hot water are provided, and the control means is set to be equal to or higher than the target temperature based on the temperature signal of the temperature detecting means. By changing the opening area of the diffusion prevention plate to heat the hot water supply water and mixing the hot water supply water with the unheated hot water supply water by the mixing means, the temperature of the hot water supply water is lowered to the hot water supply temperature. By detecting the temperature of the hot water supply flowing out of the heat exchange pipe and adjusting the natural circulation flow rate in the heat exchange area in the tank by the action of the control means, the hot water supply water can reach the target temperature or higher. The necessary and sufficient flow rate of the thermal storage fluid in order to heat can be circulated to the heat exchange area. As a result, when the heat storage fluid flows into the heat storage region through the lower opening, the temperature of the heat storage fluid can be reliably lowered to near the temperature of the hot water for heating, so that the heat in the tank It is possible to improve the utilization efficiency of hot water supply and reduce the utility bill for hot water supply.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic diagram showing the structure of a water heater according to a first embodiment of the present invention.

In FIG. 1, reference numeral 21 denotes a nighttime electric heat storage type electric water heater which is used for general household use and which stores a heat storage fluid W and heats the heat storage fluid W in the tank 22. The heating means 23 (which will be described later) and a heat exchange pipe 25 for directly exchanging heat between the tap water (hot water for hot water supply) and the heat storage fluid W which are directly connected to the water supply source 24 and flow therein. The heat storage fluid W has water as a main component, and an antiseptic agent, an antifreezing agent, LLC and the like are added as necessary. The tank 22 is, for example, a metal pressure tank, and in order to reduce the amount of heat stored in the heat storage fluid W in the tank 22 being released into the atmosphere from the wall surface of the tank 22, the outer periphery of the tank 22 is made of glass wool. It may be covered with a heat insulating material such as urethane. The heat exchange pipe 25 is the water supply source 2
4 is connected to the tank 22 from the connection inlet 26, and is spirally wound in the tank 22 to secure a sufficient heat exchange area with the heat storage fluid W, and the outlet 27 provided on the upper portion of the tank 22.
From outside the tank. The heating means 23 is formed by a tubular body having an electric heater 28 inside, one of the tubular bodies being connected to an inflow pipe 29 and the other to an outflow pipe 30, and an inflow pipe 29 and an inflow pipe 29 which are fluid heating passages. It is connected to the tank 22 via an electric pump 31 and an outflow pipe 30 provided in the middle of the. Then, the upstream end of the inflow pipe 29 opens to a substantially bottom portion inside the tank 22, and the downstream end of the outflow pipe 30 opens to a substantially top portion inside the tank 22.

Regarding the water heater constructed as above,
The operation and action will be described below.

First, the electric pump 31 is operated by using the electric power at midnight during the midnight time, and the electric pump 31 provided in the inflow pipe 29 is operated to circulate the heat storage fluid W in the tank 22 so that the electric heater is heated. 28 is energized to heat the heat storage fluid W. Since the inflow pipe 29 is opened at the bottom of the tank 22 and the outflow pipe 30 is opened at the top of the tank 22, the heat storage fluid W heated by the electric heater 28 of the heating means 23 is passed through the outflow pipe 30 to the tank 22. Since it is sent to the upper part of the inside, the heat is gradually stored in the heat storage fluid W from the upper part to the lower part in the tank 22. In addition, tank 2
Since the heat storage fluid W in 2 needs to secure the heat storage amount according to the amount of hot water used for one day at home, the tank 2 is not always required.
It is not necessary that the entire heat storage fluid in 2 be maintained at a high temperature. Therefore, in a household with a small amount of hot water supply, for example, about half the heat storage fluid W in the tank 22 may be stored. In this case, in the tank 22, as shown in FIG. 1, due to the difference in specific gravity due to the temperature of the heat storage fluid W, the heat storage fluid W1 having a higher temperature from the upper side to the lower side in the tank 22 and the intermediate temperature heat storage The fluid W2 for heat storage is naturally separated into the fluid W3 for heat storage that is not heated by the heating means 23 and has a temperature as low as the supply water temperature which is the temperature of the tap water for hot water supply. It also plays a role of insulating between the working fluid W1 and the heat storage fluid W3 having a low temperature, and the thickness thereof is smaller than that of the entire heat storage fluid.

When the user opens the hot water tap (not shown) after the heat is stored in the tank 22 by using the late night electric power which is cheap at midnight, the water for hot water supply is supplied from the water supply source 24 to the heat exchange pipe line 2.
5, and receives the heat energy of the heat storage fluid W to be heated and used for hot water supply. At this time, the heat storage fluid W1 that has stored heat at a high temperature in the upper portion of the tank 22 moves to the lower side of the tank 22 due to a temperature drop due to heat exchange with the heat exchange pipe line 25 arranged from the height in the vicinity of the outlet 27 downward. The phenomenon that the heat storage fluid W1 that does not contribute to heat exchange and remains at a high temperature moves upward due to the difference in specific gravity is repeated. In this way, hot water is discharged by direct pressure from the tap water, the heat storage fluid exchanges heat with the hot water supply water by natural convection, and the heat storage fluid W does not need to be driven to exchange heat with the hot water supply water. At times, drive power for a general electric pump as pump means is not required, and the utility cost for hot water supply can be reduced. Furthermore, if an electric pump is used for heat exchange between the heat storage fluid W and the hot water supply water, the heat storage fluid W at a high temperature is stored in the electric pump.
Therefore, it is necessary to pay sufficient attention to the reliability such as the heat resistance of the material forming the electric pump and the heat resistance of the built-in motor, but such a problem does not occur.
Further, since the water pressure system is used, there is no restriction on the hot water supply pressure (restriction of small boilers) due to tank hot water storage, and the range of use such as hot water supply on the second and third floors is expanded.

When the hot water is further supplied, the heat storage fluid W1 is deprived of heat energy and its temperature lowers. However, since the temperature does not become lower than the water supply temperature which is the temperature of the tap water for hot water supply, the heat storage fluid in the tank 22 is kept. In the area of W1, the temperature decreases due to natural convection. If the temperature of the heat storage fluid W1 drops to the same level as the temperature required for hot water supply, hot water supply becomes impossible.
Since so-called "run-out" occurs, in that case, the heat storage operation by the heating means 23 can be started again. Also in this case, the heat storage fluid W is taken out from the lower portion of the tank 22 by the electric pump 31, heated by the electric heater 28, and returned to the upper portion of the tank 22 similarly to the operation at midnight. Therefore, since it is possible to form a temperature stratification in the tank 22 that is divided into a high temperature upper layer and a low temperature to a medium temperature unheated lower layer, even if hot water runs out, the entire area of the tank is heated and heated again. Since it is possible to raise the temperature from the upper part by a required amount without any need, it is possible to save the electric power for heating required for heat storage and reduce the utility cost for hot water supply.

When the use of the hot water supply for one day is completed, the heating means 23 is operated so as to store the hot water supply heat amount enough to cover the hot water supply amount for the next day in the middle of the night. In this way, the nighttime heat storage type electric water heater 21 that heats and stores heat to cover the amount of hot water supply for one day in the middle of the night at a low price is used. Since it is possible to discharge hot water with pressure, it is possible for households that do not run out of hot water to supply the power required for hot water supply with only midnight power,
The late-night electricity rate system can reduce utility costs for hot water supply.

(Embodiment 2) FIG. 2 is a schematic diagram showing the structure of a water heater according to a second embodiment of the present invention.

In FIG. 2, a nighttime heat storage type electric water heater 21
Is composed of a tank 32, a heat pump unit 33 which is a heating means, a heat exchange conduit 34, and the like. The tank 32 is opened to the atmosphere through the air holes 32a, and the inside of the tank 32 is kept at atmospheric pressure. This tank 32
For example, it is made of a resin material and formed in a rectangular parallelepiped shape. Then, in order to reduce the heat stored in the heat storage fluid W in the tank 32 from being released into the atmosphere from the wall surface of the tank 32, the outer circumference of the tank 32 may be covered with a heat insulating material such as glass wool or urethane. good. A heat exchange pipe 34 and a diffusion prevention plate 35 are provided in the tank 32. The heat exchange pipe 34 is connected to the water supply source 24 and is inserted into the tank 32 from an inlet 26 provided at a lower portion of the tank 32. And extends upward in a meandering manner to secure a sufficient heat exchange area with the heat storage fluid W, is provided in parallel with the wall surface of the tank 32, and is piped from the outlet 27 provided at the upper portion of the tank 22 to the outside of the tank. Has been done. The diffusion prevention plate 35 is a plate-shaped heat insulating material, faces the opposite side of the tank wall surface adjacent to the meandering heat exchange conduit 34, and has a heat storage fluid passage 36 above the diffusion prevention plate 35. A space is provided between the top surface of the tank 32 and the bottom surface of the diffusion prevention plate 35 so as to form a heat storage fluid passage lower portion 37 in the space between the bottom surface of the tank 32 and the inside of the tank 32. It is divided into a heat exchange area A1 having the exchange conduit 34 and a heat storage area A2.

The heat pump unit 33 uses a supercritical heat pump cycle in which the pressure of the refrigerant on the high pressure side becomes equal to or higher than the critical pressure of the refrigerant by using, for example, carbon dioxide gas as the refrigerant. This heat pump unit 33
Is a compressor 38, a radiator 39, an expansion valve 40, an evaporator 41.
Are sequentially connected in an annular shape by refrigerant pipes, and an electric pump 31 that circulates the heat storage fluid W in the tank 32. The compressor 38 is driven by a built-in electric motor (not shown), and the evaporator 41 is driven.
The more sucked vapor-phase refrigerant is compressed to a critical pressure or higher and then discharged. The radiator 39 exchanges heat between the refrigerant and the heat storage fluid W. For example, a refrigerant passage (not shown) through which the refrigerant flows and a heat storage fluid passage (not shown) through which the heat storage fluid W flows are doubled. The counterflow heat exchanger is provided in a tubular structure and is configured such that the flow direction of the refrigerant and the flow direction of the heat storage fluid W are opposed to each other. The expansion valve 40 decompresses the refrigerant flowing out from the radiator 39 and supplies it to the evaporator 41. Evaporator 41
Causes the refrigerant decompressed by the expansion valve 40 to evaporate by heat exchange with the atmosphere and causes the gas-phase refrigerant to be sucked into the compressor 38.

The heat storage fluid passage of the radiator 39 is the inflow pipe 2
The heat storage fluid W in the tank 32 circulates when the electric pump 31 provided in the inflow pipe 29 is connected to the tank 32 via the discharge pipe 9 and the outflow pipe 30. However, the inflow pipe 29
Of the outflow pipe 30
The downstream end of is open to the top of the tank 32. As a result, the heat storage fluid W heated by heat exchange with the refrigerant in the radiator 39 is sent to the upper part of the tank 32 through the outflow pipe 30, so that the heat storage fluid W is sequentially stored from the upper part to the lower part in the tank 32. The heat is accumulated in the fluid W.

Regarding the water heater configured as described above,
The operation and action will be described below.

The heat storage fluid W in the tank 32 operates the heat pump unit 33, which is a heating means, by using, for example, late-night power, and the compressor 38 and the electric pump 31 inside the heat pump unit 33.
Is operated to heat the required amount and store heat. After that, when the user opens a hot water supply tap (not shown), hot water for hot water supply flows from the water supply source 24 to the heat exchange pipe 34, receives the thermal energy of the heat storage fluid W, is heated, and is used for hot water supply. At this time, the heat storage fluid W1 stored in the upper portion of the tank 32 in the heat exchange area A1 has a heat exchange pipe 34 in the vertically long heat exchange area A1, and heat exchanges from the upper portion to the lower portion. descend. The heat storage fluid W1 in the heat exchange area A1 whose temperature has dropped moves to the lower side of the tank 32 due to the difference in specific gravity, and further spreads to the bottom surface of the tank through the lower heat storage fluid passage 37. By this action, the heat storage fluid W1 existing in the heat storage area is drawn into the heat exchange area A1 from the heat storage fluid passage 36, the temperature is lowered by heat exchange with the hot water, and the heat storage fluid moves to the bottom surface of the tank. Bottom 37
The natural circulation of flowing into the heat storage area A2 via the above is repeated, and the operation can be performed without providing an electric pump for circulating the heat storage fluid W.

At this time, since the inlet 26 of the heat exchange pipe 34 is at the lower part of the tank and the outlet 27 is at the upper part of the tank, the hot water for hot water supply is gradually heated from the lower part to the upper part of the tank to promote heat exchange, which is necessary for the tap water temperature to the hot water supply. The temperature of the heat storage fluid W rises to a certain temperature, and while the heat storage fluid W exchanges heat from the high temperature in the upper part of the tank and moves to the lower part, the temperature drops to near the feed water temperature, and the heat storage area A2
The temperature becomes almost equal to that of the heat storage fluid W3. Therefore, since the upper part of the tank is kept relatively high and the lower part approaches the water supply temperature, the temperature of the heat storage fluid W in the entire tank decreases due to the heat dissipation by using the hot water, and the high temperature required for the next hot water supply. It becomes possible to prevent the hot water supply from becoming impossible, and the heat quantity in the tank can be efficiently used for the hot water supply, and the utility cost for the hot water supply can be reduced.

Further, a diffusion prevention plate 35 made of a heat insulating material is provided in the tank 32 to separate it into a heat exchange area A1 and a heat storage area A2, and a heat exchange pipe 34 is provided in the heat exchange area A1 and the lower part thereof is provided. Since the hot water for hot water is circulated from the upper part to the upper part, the diffusion prevention plate 35 promotes the natural circulation of the heat storage region A1 and the heat storage region A2 of the heat storage fluid W, and only the heat exchange region A1 near the heat exchange pipe 34. Since heat exchange is performed in the tank 32
It is possible to prevent the entire temperature from being uniformly lowered, to maintain the temperature stratification of the heat storage area A2 in the tank 32, to improve the utilization efficiency of the hot water supply in the tank, and to reduce the utility cost for hot water supply.

When the use of hot water for one day is completed, the heat pump unit 33 is operated in the midnight time period to heat the heat storage fluid W to store heat in the tank 32. At this time, in the heat pump cycle, the coefficient of performance (COP = heating capacity / power consumption) can be operated with at least 1 or more, and depending on the conditions, the coefficient of performance can be about 3, so that it is necessary to heat the heat storage fluid W. The electric power can be reduced to 1/3 of that in the case of using an electric heater, and a significant saving of utility costs can be realized. Further, when the heat storage fluid W is heated to the temperature for hot water supply (for example, 65 to 90 ° C.) by the heat pump cycle, the higher the temperature of the heat storage fluid W before heating is, the higher the high pressure can be made, so that the coefficient of performance is improved. Therefore, the coefficient of performance is further improved by heating the heat storage fluid W stored in the lower part of the tank by the heat pump cycle, the temperature of which is lowered to near the feed water temperature by the above-mentioned natural circulation action, and further power saving operation is performed. Utility costs can be reduced.

Further, in this embodiment, the tank 3 which is open to the atmosphere is used.
Since No. 2 is used, a pressure resistant design such as a pressure tank (sealed tank) is not necessary, so that the tank 32 can be molded with resin. In this case, the press process and welding process required for processing stainless steel, which is usually used as a tank material, are not required, and the manufacturing cost can be kept lower than before. In addition, parts such as a pressure reducing valve, a pressure relief valve, a negative pressure actuating valve, and a can body protection valve, which are necessary for a configuration using a pressure tank, are unnecessary. Further, unlike a pressure tank, it is not necessary to have a cylindrical shape from the viewpoint of pressure resistance, and the degree of freedom in designing the tank shape can be increased.

(Embodiment 3) FIG. 3 is a schematic diagram showing the structure of a water heater according to a third embodiment of the present invention.

In FIG. 3, a space is provided above the diffusion prevention plate 35 so as to form a heat storage fluid passage 36 that is an upper opening, and a space is provided below the diffusion prevention plate 35 so as to form a top surface inside the tank 32. Forms a lower heat storage fluid passage 37, which is a lower opening, in a gap from the bottom surface of the tank 32. A movable plate 43 having a rack 42 and a motor 45 having a pinion 44 are provided so that the opening area of the heat storage fluid passage bottom 37 can be changed to configure a rack and pinion mechanism. Heat exchange pipe 3 connected to the water supply source 24
4 has a branch pipe 46 branched and connected to the heat exchange pipe 34 upstream of the inlet 26, and the downstream end of the branch pipe 46 is a mixing means provided downstream of the outlet 27 of the heat exchange pipe 34. The hot water supply water, which is connected to the mixing valve 47 and flows out from the heat exchange pipe 34, is mixed with the hot water supply water flowing from the unheated branch pipe 46 by the mixing valve 47, and the hot water is discharged. Further, the heat exchange pipe 34 is provided with a thermistor 48, which is a temperature detecting means for detecting the temperature of the hot water for hot water flowing out from the heat exchange pipe 34, downstream of the outlet 27. The control means 49 includes a thermistor 48 and a motor 45.
The opening area of the diffusion prevention plate 35 is changed by driving the motor 45 to move the movable plate 43 up and down based on the transmitted temperature signal of the thermistor 48.

Regarding the water heater constructed as above,
The operation and action will be described below.

When the user opens a hot water supply tap (not shown), hot water for hot water supply flows from the water supply source 24 to the heat exchange pipe 34, receives heat energy of the heat storage fluid W, is heated, and flows into the mixing valve 47. To do. In the mixing valve 47, the hot water that has flowed in and the branch pipe 4
The flow rate ratio of the inflowing water is varied from 6, and the temperature of the hot water for hot water supply is lowered to the temperature at which hot water should be supplied up to an appropriate temperature (for example, 40 ° C.) of hot water supply of about 35 to 50 ° C. At the same time, in the tank 32, the heat storage fluid W stored at a high temperature in the upper portion of the tank 32
The one in the heat exchange area A1 of the
And heat is exchanged from the upper part to the lower part and the temperature drops. The heat storage fluid W1 in the heat exchange area A1 whose temperature has dropped moves to the lower side of the tank 32 due to the difference in specific gravity, and further below the heat storage fluid passage 3
It spreads through 7 to the bottom of the tank. The heat storage fluid W below the heat storage fluid passage 37 which is the lower opening of the diffusion prevention plate 35
Since the flow resistance varies depending on the opening area of the heat storage fluid, the amount of movement of the heat storage fluid W moving downward in the heat exchange area A1 can be changed by the opening area. Due to the downward movement of the heat storage fluid W, the heat storage fluid W1 existing in the heat storage area A2 is on the heat storage fluid passage 36.
Is drawn into the heat exchange area A1 and the natural circulation of the heat storage fluid W is repeated. At this time, the control means 49 has a temperature (for example, 55 ° C.) higher than the optimum temperature (40 ° C.) of hot water supply as the target temperature, and the hot water supply water flowing out from the heat exchange pipe 34 based on the temperature signal of the thermistor 48. The motor 45 is driven so that the temperature is at least 55 ° C. or higher, and the opening area of the heat storage fluid passage bottom 37 is changed by the vertical movement of the movable plate 43 driven by the motor 45, whereby the heat exchange area A1 in the tank 32 is changed. Adjust the natural circulation flow rate.

As described above, by changing the opening area of the heat storage fluid passage bottom 37 by the vertical movement of the movable plate 43 driven by the motor 45, the circulation resistance of the natural circulation of the heat storage fluid W can be changed. By controlling the natural circulation flow rate in the heat exchange area A1, the temperature of the heat storage fluid W flowing into the heat storage area A2 through the heat storage fluid passage bottom 37 after heat exchange can be reduced to near the temperature of the hot water supply water before heating. This allows
It is possible to maintain the temperature stratification in the heat storage area in the tank and increase the temperature difference between the upper and lower sides, improve the utilization efficiency of hot water in the tank for supplying hot water, and reduce the utility cost for supplying hot water.

Further, since the control means 49 drives the motor 45 based on the temperature signal of the thermistor 48 to change the opening area, the temperature of the hot water for hot water flowing out from the heat exchange pipe 34 is set to 55 ° C. necessary for hot water supply. The circulation flow rate can be reduced to a level that does not fall below the limit. Therefore, when the heat storage fluid W flows into the heat storage area A2 through the heat storage fluid passage bottom 37, the temperature of the heat storage fluid can be reliably lowered to near the temperature of the hot water supply water before heating.
It is possible to improve the utilization efficiency of the hot water supply in the tank, and reduce the utility cost for hot water supply.

In this embodiment, the structure in which the opening area of the heat storage fluid passage bottom 37 which is the lower opening of the diffusion prevention plate 35 is changed by the movable plate 43 and its rack and pinion mechanism has been described as an example. The same action and effect can be obtained with the upper opening instead of the lower opening, or with both the upper opening and the lower opening, and opening area varying means other than the rack and pinion mechanism may be used.

Further, in the present embodiment, the mixing valve 47, which is a mixing means, has been described as an element constituting the electric water heater 21, but the same operation and effect can be obtained even if the hot water tap which is a terminal is provided with the mixing means. It is obvious that

[0041]

As described above, according to the present invention, it is not necessary to drive the pump means for heat exchange between the heat storage fluid and the hot water supply water. It becomes unnecessary, and the utility bill for hot water supply can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a water heater according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a water heater according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a water heater according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional water heater.

[Explanation of symbols]

21 Electric water heater (night heat storage type water heater) 22, 32 tank 23 Heating means 25, 34 heat exchange lines 26 entrance 27 exit 29 Inflow pipe (fluid heating passage) 30 Outflow pipe (passage for fluid heating) 33 Heat pump unit (heating means) 35 Diffusion prevention plate 36 On the heat storage fluid passage (upper opening) 37 Under heat storage fluid passage (lower opening) 38 compressor 39 radiator 40 Expansion valve (pressure reducing means) 41 Evaporator 47 mixing valve (mixing means) 48 Thermistor (temperature detection means) 49 control means A1 heat exchange area A2 heat storage area W Heat storage fluid

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Watanabe             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Satoshi Imabayashi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Satoshi Matsumoto             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 3L036 AB07

Claims (8)

[Claims] 1. A tank for storing a heat storage fluid, a heating means for heating the heat storage fluid, an inlet side directly connected to tap water, an outlet at the top of the tank, and an outlet provided in the tank for supplying hot water. A water heater comprising: a heat exchange pipe for exchanging heat with the heat storage fluid, and supplying tap water heated by heat exchange in the heat exchange pipe. 2. The water heater according to claim 1, wherein an inlet of the heat exchange pipe to the tank is provided at a lower portion of the tank. 3. A fluid heating passage is provided, wherein a heat storage fluid is taken out from a lower portion in the tank and supplied to a heating means, and the heat storage fluid heated by the heating means is returned to an upper portion in the tank. The water heater according to 1 or 2. 4. The water heater according to any one of claims 1 to 3, wherein the heating means is operated in the midnight time zone by utilizing the midnight electricity rate system. 5. The water heater according to claim 1, wherein the heating means is a heat pump unit having a compressor, a radiator, a pressure reducing means, and an atmospheric heat exchanger that is an evaporator. 6. A heat exchange conduit is provided substantially parallel to the tank wall surface from an inlet at the lower part of the tank to an outlet at the upper part, and a diffusion prevention plate is provided on the opposite side of the heat exchanger conduit from the tank wall surface, The heat storage fluid that has radiated heat is prevented from diffusing and the inside of the tank is divided into a heat exchange area and a heat storage area.
The water heater according to any one of 5 above. 7. A diffusion prevention plate having both an upper portion and a lower portion opened so that the heat exchange area and the heat storage area communicate with each other,
The water heater according to claim 6, wherein the opening area of at least one of the upper opening and the lower opening of the diffusion prevention plate is changeable. 8. A control means having a target temperature set higher than the hot water supply temperature, a temperature detecting means for detecting the temperature of the hot water supply water flowing out from the heat exchange conduit, and a hot water supply water heated and flowing out from the heat exchange conduit. And mixing means for mixing unheated hot water for hot water supply, wherein the control means changes the opening area of the diffusion preventive plate so as to be equal to or higher than the target temperature based on the temperature signal of the temperature detection means. The water heater according to claim 7, wherein the temperature of the hot water supply water is lowered to the hot water supply temperature by heating and mixing the hot water supply water with the unheated hot water supply water by the mixing means.