JPS63105362A - Electric water heater - Google Patents

Abstract

PURPOSE:To be able to maintain the capacity to supply hot water constant regardless of the change in temperature of a solid heat storage body, by controlling the flow rate of air to be fed toward the solid heat storage body in accordance with the temperature of a solid heat storage body. CONSTITUTION:Heat is accumulated in a solid heat storage body 4 so that the accumulated amount of heat becomes the maximum predetermined temperature by heating the storage body 4 by electric heaters 8 for a predetermined time, and the temperature at the time is detected by a temperature sensor 28. A water flowing into water pipes 21 is controlled by a flow switch 29 provided in a feed water pipe 23, and the flow rate of hot water, discharged from a feed hot water pipe 24, that is, the flow rate of water flowing through the water pipe 21, is controlled by a valve 25, the temperature in hot water is set in accordance with the flow rate of hot water, and the temperature is detected by a temperature sensor 30 provided in the feed hot water pipe 24. The upper limit number of revolution of a fan 16 is changed in accordance with the temperature in the solid heat storage body 4 in order to maintain the capacity to supply hot water constant, and the number of revolution of a fan is also changed into the number below the upper limit in accordance with the temperature in hot water which is going to be obtained. In such a manner the capacity to supply hot water can be maintained constant and stable supply of hot water can be taken place regardless of the change in temperature in the solid heat storage body.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electric water heater using a solid heat storage body.

[Prior Art] Conventionally, electric water heaters used at home to supply hot water for showering, washing hands, etc. are generally of a hot water storage type. This hot water storage type electric water heater is installed by inserting an electric heater (seed heater) inside a tank that stores hot water, and directly heats the water supplied inside the tank with the electric heater and stores it in the tank trap. When hot water is supplied, hot water is discharged from the tank to the outside.

[Problems to be Solved by the Invention] However, electric water heaters are required to be able to supply hot water continuously during hot water supply.

However, in order to meet the above requirements in conventional hot water storage type electric water heaters, they rely on heat storage by the hot water stored in the tank. however,
Water has both a specific heat and a specific gravity of 1, and can only be heated up to a maximum of 100°C. Therefore, in order to store a large amount of heat in a hot water storage type electric water heater, a large capacity hot water storage tank is required to store a large amount of hot water.

For this reason, the entire water heater becomes large and requires a large installation space, and there is a problem that it becomes difficult to install an electric water heater depending on the location.

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide a heat storage type electric water heater that is small in size, can store a large amount of heat, and can maintain a constant hot water supply capacity. .

[Means and effects for solving the problem] The electric water heater of the present invention includes a solid heat storage body, an electric heater that heats the solid heat storage body to store heat, and a blower that blows air toward the solid heat storage body. and a heat exchanger that exchanges heat between the air sent by the blower and heated by the solid heat storage body and water to turn the water into hot water, the heat exchanger changing the temperature of the solid heat storage body according to the temperature of the solid heat storage body. This system is characterized by varying the flow rate of the air sent toward the solid heat storage body.

That is, by using a solid heat storage body as a heat storage body that stores the heat for heating water, the size is reduced, and furthermore, the amount of air supplied to the solid heat storage body is adjusted according to the temperature change of the solid heat storage body. K is set so that the hot water supply capacity can be maintained constant regardless of temperature changes in the solid heat storage body.

[Example] Embodiments of the present invention will be described below with reference to convention.

1 to 3 show an embodiment of the electric water heater of the present invention.

In the figure, 1 is a box-shaped case, and in this case 1, insulation panels 2 are combined to form side walls 1a, 1b, 1c.
.

1d and the ceiling wall 1. The bottom wall 1b is made of a metal plate.

A heat storage unit 3 for heating the air inside the case 1 is provided in the upper half of the case 10. It is constructed by stacking heat storage bodies 4. In other words, 1 m of opposing side walls in case IK
, Ib, a heat insulating material panel 5 is installed at an intermediate position in the vertical direction, and on this heat insulating material panel 5, a large number of solid heat storage bodies 4 are placed horizontally and stacked in multiple stages vertically. In addition, when combined in parallel in the vertical and horizontal directions, the thickness direction (
It is formed by penetrating between both side surfaces along a direction perpendicular to the longitudinal direction. In the heat storage unit 31C, each solid heat storage body 4 is stacked adjacently on top and bottom and on both sides.
In combination, the grooves 6 formed in the heat storage unit 3 as a whole form a plurality of circular holes that extend through the unit and are arranged parallel to the side wall 1 m, lb of the case 1 at each boundary of each stacking stage. 7 is formed. In addition, between the opposite side surfaces of the solid heat storage bodies 40 adjacent to each other in each stacked stage of the heat storage body unit 3, a large number of sheathed heaters, that is, electric heaters 8 for storing heat in the solid heat storage body 4 are installed on the side wall 1 m of the case 1. Ib
The electric heaters 8 are provided overflowing in the length direction of the solid heat storage bodies 4 arranged in between, and the electric heaters 8 fit into grooves 9 formed on the side surfaces of each solid heat storage body 4 and are tightly attached to the side surfaces. It is being pinched.

That is, each electric heater 8 is connected to the side wall ia of the case 1.

1b to make contact with the side surface of each solid heat storage body 4 lined up between the side walls 1a and Ib, and both ends of each electric heater 80 are inserted into the side wall 11 of the case 1, and the side wall It is connected to a control circuit provided on a control panel 10 mounted on the outside of 1a.

Inside the case 1, there is a lower space 11 below the heat storage unit 3, that is, a space between the heat insulating material channel 5 and the bottom wall 1b of the case 1, and a side space 12 on the side of the heat storage unit 3. .13, that is, the space between the heat storage unit 3 and the side walls io, ld of the case 1, and the upper space 14 above the heat storage unit 3, that is, the space between the heat storage unit 3 and the case 1.
The air holes 7 of the heat storage unit 3 and the side spaces 12, 13 are in communication with each other.

Each of the spaces 11 to 14 and the air holes 7 of the heat storage unit 3 form an air passage 15 through which air inside the case 1 is circulated.

In the lower space 11 inside the case 1, a part located below one side space 12, that is, a corner where the lower space 11 and the side space intersect, is provided with a hole for blowing and circulating the air in the air passage 15. A blower 16 is installed. The blower 16 is, for example, a sirocco fan equipped with a multi-blade rotary blade 18, and the suction port 17a of the case 17 is provided toward the lower space 1111C and the discharge port 17b toward the side space 12, respectively. The motor 19 that rotationally drives the blower 16 is installed outside the side wall IC of the case 1.
The drive shaft of this motor 19 and the rotary blade shaft of the blower 16 are connected via the side wall 1c.

Note that the motor 19 is connected to a control circuit provided in the control panel 10.

Further, a heat exchanger 20 for obtaining hot water is installed in the center of the lower space 1 inside the case 1. This heat exchanger 2Q is composed of a water flow pipe 2 for flowing water and a large number of heat transfer fins 22 that come into contact with the air flowing through the air passage 15 of the case 1. The water flow pipe 21 is arranged in a meandering manner between the side walls 78° 1b of the case 1, and both ends pass through the one side wall 1a and are led out to the outside, and the heat transfer fins 22 are attached to the water flow pipes 21. side wall 1m.

They are arranged side by side between lbs. A water supply pipe 23 and a hot water supply pipe 24 are disposed outside the side wall 1a of the case 1. One end of the water supply pipe 23 is connected to one end of the water flow pipe 21 led out through the side wall 1a of the case 1, and the other end of the water supply pipe 23 is connected to a water supply source (not shown), that is, a water pipe. be. One end of the hot water pipe 24 is connected to the other end of the water flow pipe 2 led out from the side wall 1 & of the case 1, and a faucet 26 is connected to the other end of the hot water pipe 24 via a valve 25. be. Note that 22 is a pump provided outside the case 1, and this pump 27 is connected to the water supply pipe 23.

Next, control in this regenerative electric water heater will be explained.

The solid heat storage body 4 is heated by an electric heater 8 for a certain period of time to store heat to a predetermined maximum temperature.

The temperature of the solid heat storage body 4 is detected by a temperature sensor 28.

The blower 16 is used during hot water supply, that is, when the water flow pipe 2 of the heat exchanger 20
It is driven to rotate only when water is flowing through the pipe 1, and when hot water is not being supplied, that is, when water is not flowing through the water flow pipe 21, the drive is stopped to prevent dry cooking. The flow of water in the water flow pipe 21 is controlled by a flow switch 29 provided in the water supply pipe 23. The flow rate of hot water discharged from the hot water supply pipe 24, that is, the flow rate of water flowing through the water flow pipe 2, is adjusted by a valve z5, and the temperature of the hot water is set according to the flow rate of this water.

The temperature of the hot water is detected by a temperature sensor 30 provided in the hot water supply pipe 24.

In order to keep the hot water supply capacity constant, the blower 16 changes its upper limit rotation speed according to the temperature of the solid heat storage body 4.
In addition, the rotational speed is changed below the upper limit rotational speed according to the temperature of the hot water to be obtained.

Here, an explanation will be added regarding the relationship between the operating conditions of the blower 16 and the hot water supply capacity. The hot water supply capacity indicates the amount of hot water supplied when the temperature difference between water and hot water is maximum, and further indicates the hot water supply time when the hot water temperature is the highest and the maximum flow rate is reached. For example, assume that water at an inlet temperature of 20°C can be heated to 70°C and hot water can be supplied for 80 minutes at a rate of 151/min. ! In addition, the temperature range of the solid heat storage body 4 is determined in relation to the hot water supply capacity. For example, 150℃~65
The temperature shall be 0°C. Now, the amount of heat on the air side heated by the solid heat storage body 4 is defined by the temperature of the solid heat storage body 4 and the flow rate of the air. Further, the amount of heat on the hot water side obtained by heat exchange between air and water in the heat exchanger 20 is defined by the temperature difference between the water supply section and the hot water supply section and the flow rate of water. The hot water supply capacity is determined by the amount of heat on the air side. However, the temperature of the solid heat storage body 1 is the highest at the time when heat storage by heating by the electric heater 8 ends, and thereafter the temperature gradually decreases due to heat radiation as time passes.

Therefore, when the air flow rate is constant, the amount of heat on the air side changes (decreases) in accordance with the temperature change (temperature decrease) of the solid heat storage body 4, and the hot water supply capacity is affected accordingly. As a result, its size changes (decreases). Therefore, in the present invention, the amount of heat on the air side is kept constant regardless of the temperature change of the solid heat storage body 4 by changing the flow rate of the air in accordance with the temperature change of the solid heat storage body 4, thereby increasing the hot water supply capacity. maintain a constant size. That is, specifically, when the temperature of the solid heat storage body 4 is the lowest, the rotation speed of the blower 16 is set to the maximum to maximize the flow rate to −je4 of air, and each time the temperature of the solid heat storage body 4 rises, The rotational speed of the blower 16 is gradually lowered from the maximum rotational speed to reduce the flow rate of air, and when the temperature of the solid heat storage body 4 is at its highest, the blower 16 is turned off.
The upper limit rotational speed of the engine is minimized to minimize the amount of air exhaust. Note that each upper limit rotation speed corresponding to the temperature of the solid heat storage body 4 is set to a value that allows a predetermined hot water supply capacity to be maintained constant.

FIG. 4 is a diagram showing an example of the relationship between the temperature of the solid heat storage body and the upper limit rotation speed of the blower. Then, the blower 16 is operated so as to obtain an air flow rate (air volume) corresponding to the temperature of the hot water to be obtained within the range of the upper limit rotation speed set according to the temperature for each temperature stage of the solid heat storage body 4. Adjust the rotation speed. Note that the rotation speed of the blower 16 is controlled by the control circuit.

The operation of the electric water heater configured in this way will be explained.

First, the electric heater 8 is energized to heat each solid cover heating element 4 of the heat storage unit 3 by the heat generated, and the temperature of each solid heat storage element 4 is raised to a predetermined temperature to perform heat storage. This heat storage is performed, for example, by energizing the electric heater 8 using late-night electricity for eight hours at night.

Since the heat storage unit 3 has a large number of solid heat storage bodies 4 stacked together and a large number of electric heaters 8 arranged between each solid heat storage body 4, the entire solid heat storage body 4 can be heated efficiently and sufficiently. can be used to store heat.

Next, when hot water is to be supplied, the valve 2 connected to the hot water supply pipe 23 is
5 is opened, and water supplied from the water pipe is allowed to flow into the water flow pipe 21 of the heat exchanger 20 inside the case 1 through the water supply pipe 23. Depending on the opening degree of the valve 25, the flow rate of water, that is, the flow rate of hot water, and the temperature of hot water are determined. Water supply pipe 231C
When water flows, the 70-switch 29 detects this, and the motor 19 is started based on the detection signal of the flow switch 29 and is regulated according to the temperature of the solid heat storage body 4. Blower 16
The air in the air passage 15 of the case 1 is sent toward the heat storage unit 3 by the drive of the heat storage unit 3 . That is, the air passes through an air passage 15 connecting the lower space 11, the side spaces 12, 13, the upper space 14, and the large number of air holes 7 formed between the solid heat storage bodies 40 of the heat storage unit 3 inside the case 1, as indicated by the arrows in the figure. Flows in a circular direction. In this case, air is sent from the lower space 11 of the case 1 to the side space 12 by the drive of the blower 16, rises and flows, and passes through the many air holes 7 of the heat storage unit 3. When passing through the air pores 7, it comes into contact with the surface of each solid heat storage body 40 over a wide area, and is efficiently heated by the heat released from each solid heat storage body 4, thereby raising the temperature. The air passing through the air holes 7 of the heat storage unit 3 flows into the side space 13
The air descends and enters the lower space JJK, and passes between the heat exchanger 2017 (a large number of heat transfer fins 220 provided therein. At this time, the air contacts the heat transfer fins 22 and the heat of the air is transferred to the heat transfer fins 22 and is transmitted to the water flowing in the water flow pipe 21 via the water flow pipe 21.In particular, heat exchange takes place between the air and water, and the temperature of the air decreases, and the water is heated and rises in temperature, turning into hot water. Thereafter, the air is blown from the lower space 11 by the blower 16.The hot water is sent to the water flow pipe 21 of the heat exchanger 20.
The hot water passes through the hot water supply pipe 24 and is discharged from the faucet 26.

On the other hand, when hot water passes through the hot water pipe 24, the hot water temperature adjustment sensor 3
0 detects the temperature of hot water, and based on the detection signal from this sensor 30, the rotation of the motor 19 is controlled and the blower 16
The rotation speed is controlled.

That is, the rotation speed of the blower 160 and the rotary blade 18 is controlled so that the air in the air passage 15 flows at a flow rate that corresponds to the temperature of the hot water. Therefore, the temperature of the desired hot water can be maintained constant. By continuously changing the flow rate of the air in the air passage 15 in this way, the temperature of the hot water can be changed continuously, so any desired temperature can be easily obtained continuously. be able to.

In addition, the blower 16
By changing the upper limit rotation speed of the air passage 15 and controlling the flow rate of the air flowing through the air passage 15,
It is possible to maintain stable hot water supply by maintaining the hot water supply capacity at a constant level. If such control is not performed, for example, when the temperature of the solid heat storage body 4 is high, the blower 16
A situation arises in which the rotational speed of the fan 16 is too high and the hot water supply capacity is too high, and if the upper limit rotational speed of the blower 16 is suppressed in response to this situation, when the temperature of the solid heat storage body 4 decreases, the rotational speed of the blower 16 is too low. Without the hot water supply capacity being insufficient, the hot water supply capacity cannot be maintained at a constant level.

Then, when the valve 25 is closed, the flow of water in the heat exchanger 20 is stopped. In this case, the flow switch 29 detects the stoppage of the flow of water in the water supply pipe 23, and the blower 16 stops driving due to the signal from the 70-switch 29, and the circulation of air in the air passage 15 also stops.

Therefore, the electric water heater explained in this example is
Since the solid heat storage body 4 is used to store the heat for heating water to obtain hot water, it is possible to achieve a smaller size than a conventional hot water storage type electric water heater.

For example, magnesia used as the solid heat storage body 4 has a specific heat of 0.3 and a specific gravity of 3, and can have a heat storage temperature of 500° C. or higher. Therefore, it is possible to obtain a large heat storage capacity while being smaller than a storage type electric water heater.

In addition, in the above-mentioned embodiment, the rotation speed of the blower is changed in order to adjust the flow rate of air in the air passage, but the invention is not limited to this. The air flow rate may be set to v4.

[Effects of the Invention] As explained above, according to the electric water heater of the present invention, since a solid heat storage body is used as a heat storage body for storing heat for obtaining hot water, it is possible to store a large amount of heat while being small. Hot water can be supplied continuously with good start-up. Moreover, the hot water supply capacity can be maintained constant regardless of temperature changes in the solid heat storage body, and hot water can be supplied stably.

[Brief explanation of the drawing]

The drawings show one embodiment of the electric water heater of the present invention, and FIG. 1(a) is a longitudinal sectional front view, FIG. 1(b) is a front view showing the arrangement of water supply pipes and hot water supply pipes, and FIG. FIG. 2 is a longitudinal sectional plan view, FIG. 3 is a cross-sectional view, and FIG. 4 is a diagram showing the relationship between the temperature of the solid heat storage body and the rotation speed of the blower. DESCRIPTION OF SYMBOLS 1... Case, 3... Heat storage unit, 4... Solid heat storage body, 7... Air hole, 8... Electric heater, 15
... Air passage, 16... Air blower, 20... Heat exchanger, 23 River water supply pipe, 24... Hot water supply pipe. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A solid heat storage body, an electric heater that heats the solid heat storage body to store heat, a blower that blows air toward the solid heat storage body, and air and water that are sent by the blower and heated by the solid heat storage body. and a heat exchanger that converts the water into hot water by exchanging heat between the two, and changing the flow rate of air sent toward the solid heat storage body according to the temperature of the solid heat storage body. vessel.