The present invention relates to a swltomngl regenerative type midnight electric boiler and water heater utilizing a midnight electric power, and more particularly to a switching regenerative type midnight electric boiler and water heater with an exterior heating device, which can get the same effect by a more simplified apparatus by improving a pipe connecting structure of the midnight electric boiler and water heater having the heating device, a circulating pump, and a solenoid or motorized valve mounted at an outside wall of the regenerative type midnight electric boiler and water heater.

Description of Related Art A regenerative type midnight electric boiler and water heater mostly uses a midnight electric power. The midnight electric power service is available during midnight hours, i. e., from ten p. m. to eight a. m. or from eleven p. m. to nine a. m., in which electric power consumption is small. This service is a policy, which supplies a generated dump power in midnight hours, so that it can be used at an electric charge which is much cheaper than a customer charge, thus dispersing power consumption, most of which is concentrated on the daytime. In addition, it reduces the import of crude oil for heating purpose and maximizes the efficiency of power generation facilities.

Such a common regenerative type midnight electric boiler is provided with a relatively large type heat storage tank, the heat storage tank having an electrical heater for heating hot water therein. The electrical heater is operated mostly in midnight power supply time for thereby heating water or latent heat material therein. Therefore, the water heated and the heat stored in the latent heat material during nighttime are used in the daytime, thusly,

hot water as well as heating can be used at a lower charge.

However, the above-described regenerative type midnight electric boiler and water heater is subject to the following drawbacks. When it is desired to use heating system and hot water during nighttime in the state where the heat storage material in the heat storage tank has all been used up and the heat storage tank becomes cooled, space heating and hot water are not supplied until the water or latent heat material in the heat storage tank reaches the proper temperature for use.

That is to say, more than one or two heaters starts operation as the power is turned on at ten or eleven p. m. at which the nighttime hours start, and thusly the entire heat storage tank must be heated so that space heating and hot water can be used within a short time, thus requiring a large capacity of electrical power. This causes excessive investment cost of distribution lines of power supply and facility companies and occurs a problem in the efficient use of plant power.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a switching regenerative type midnight electric boiler and water heater with an exterior heating device, which allows the heat storage operation of latent heat material and the circulation of hot water, enables the instantaneous use of space heating and hot water only by a heater of a small capacity even in the midnight power supply hours, and reduces investment cost by sharing a midnight power load, by having the heating device at an outside wall of the heat storage tank of the regenerative type midnight electric boiler and water heater and a circulating pump and a solenoid or motorized three-way valve at the center portion of the body of the pipe connected thereto.

Furthermore, it is not impossible at all to employ the exterior heating device of the invention to the regenerative type electric boiler being commonly used currently, the utilization ratio thereof is improved.

To achieve the above object, there is provided a switching regenerative type midnight electric boiler and water heater with an exterior heating device according to the present invention, comprising: a heating means for heating a heat storage material in a heat storage tank; a heat storage material heating means being mounted to the outside of the heat storage tank and having a plurality of radiating fins at a vertically constant interval; and a valve and a pump mounted at a circulating pipe, wherein the heat storage material heated from the heat storage tank and the heat storage material heating means are circulated as a direction switching means and the pump are organically operated according to whether a midnight power is supplied and whether space heating/hot water is used.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an overall sectional explanatory view of a switching regenerative type midnight electrical boiler according to the present invention.

Fig. 2 is a detail sectional view of a heating device of the switching regenerative type midnight electrical boiler according to the present invention.

Fig. 3 is a perspective view showing a radiating fin connecting structure in the heating device of the switching regenerative type midnight electrical boiler according to the present invention.

Fig. 4 is a flow chart of a heat storage material in the switching regenerative type midnight electrical boiler according to the present invention when a midnight electricity is applied and hot water or space heating is used.

Fig. 5 is a flow chart of a heat storage material in the switching regenerative type midnight electrical boiler according to the present invention when a midnight electricity is applied and any hot water or space heating is not used.

Fig. 6 is a flow chart of a heat storage material in the switching regenerative type midnight electrical boiler according to the present invention when a midnight electricity is not applied and hot water or heating is used.

Fig. 7 is an automatic control circuit diagram of the switching regenerative type midnight electrical boiler according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS A preferred embodiment of the present invention will now be described.

Fig. 1 is an overall sectional explanatory view of a switching regenerative type midnight electrical boiler according to the present invention; Fig. 2 is a detail sectional view of a heating device of the switching regenerative type midnight electrical boiler according to the present invention; and Fig. 3 is a perspective view showing a radiating fin connecting structure in the heating device of the switching regenerative type midnight electrical boiler according to the present invention.

In the switching regenerative type midnight electrical boiler, a heat storage tank 2 with an insulating layer 1 has a plurality of heaters 3 and 3'at an inner side wall and it has an inlet pipe 5 with a circulating pump 4 and a outlet pipe 6 at an outside wall, the inlet pipe 5 and the outlet pipe 6 being configured to pass through internally and exteriorly the heat storage tank 2.

Discharging pipes 6 and 6', which are formed outside the heat storage tank 2, are separated from each other. A heating device 8 having a heater 7 therein is mounted at the end portion of the outlet pipe 6 of the heat storage tank 2. A connecting pipe 9, which is drawn from the lower end of the heating device 8, is connected to the inlet pipe 5. The separated outlet pipe 6'is connected to the connecting pipe 9 and the outlet pipe 6 and the inlet pipe 5 are connected to each other by a circulating pipe 10. At the portions where the inlet pipe 5 and the connecting pipe 9 are joined and the inlet pipe 5 and the circulating pipe 10 are joined, three-way valves 11 and 11'are mounted respectively. At the inlet pipe 5 between the three-way valves 11 and 11', the circulating pump 4 is mounted.

Additionally, the heater in the above-described heating device 8 is downwardly connected by a flange 12. A plurality of radiating fins 14 and 14'with a vent hole 13,

which are vertically separated from each other, are formed at the peripheral portion of the heater 7. In detail, the vent holes 13 formed at the radiating fins 14 and 14'are formed vertically in zigzag, and thusly a high temperature conduction is generated more quickly by the radiating fins 14 and 14'.

Unexplained reference numeral 20 is a power switch.

The operation of the thusly constructed switching regenerative type midnight electric boiler will now be described in more detail with reference to the accompanying drawings.

Firstly, a typical regenerative type midnight electric boiler and water heater starts up the heaters 3 and 3'in order to heat the water or latent heat material in the heat storage tank 2 in the nighttime, which has been cooled by using a heat storage material with a heat energy stored in the daytime using a midnight electricity. Then, the vicinity of the heaters 3 and 3'is firstly heated by heat generation of the heaters 3 and 3'. Thusly, at this time, it is impossible to use space heating and hot water.

Therefore, by means of an exterior heating device 8, only the water or latent heat material circulating in the heating device 8 is rapidly heated to thus be circulated indoors, which enables the use of space heating and hot water simultaneously with the applying of the power of the heating device 8.

In other words, since the amount of the heat storage material in the heating device 8 is relatively small, when a power is applied to the heater 7 downwardly connected to the upper end of the heating device 8 by the flange 12, the heat storage material in the heating device 8 is heated within a relatively short time.

Therefore, this makes it possible to use rapid heating and instantaneous hot water.

Particularly, the radiating fins 14 and 14'formed in the heating device 8 and the vent holes 13 formed at the radiating fins 14 and 14'delays the transport speed of the heat storage material flowing in the heating device 8, thus enabling heating to a higher temperature.

While using such a temporary space heating and hot water, when the temperature of the entire water or latent heat material is increased to a predetermined temperature by the heaters 3 and 3'in the heat storage tank 2, the water or latent heat material in the heat

storage tank 2 becomes circulated by the circulating pump 4, which enables a continuous use of space heating and hot water.

Hence, even though the temperature of the heat storage material in the heat storage tank was not increased to a predetermined temperature, if it is desired to use space heating and hot water quickly, this can be achieved by the heating device 8. In addition, since simultaneous heating is accomplished continuously by the heaters 3 and 3'in the heat storage tank 2, the water or latent heat material in the heat storage tank 2 is sufficiently heated after a predetermined time. This enables continuous space heating and hot water heating. Of course, it is possible to use space heating and hot water by storing a high temperature thermal energy at the nighttime and then circulating a high temperature water or latent heat material even if there was no heating operation during the daytime.

Such a switching regenerative type midnight electric boiler and water heater by the heating device according to the present invention shows different ways in its operation according to power supply types (midnight power supply and primary power supply) and whether space heating or hot water is used or not. This will now be described in more detail.

As shown in Fig. 4, a power switch 20 is operated for supplying power to the heaters 3 and 3'in the heat storage tank 2 during the nighttime, and an indoor switch (not shown) is turned on for using space heating and hot water. Simultaneously, the three-way valve 11 of a solenoid or motorized type, which is mounted to the portion where the inlet pipe 5 and the circulating pipe 10 are joined, is operated to make the connecting pipe 9 and the inlet pipe 5 at the discharging side communicate with each other. The three-way valve 11', which are mounted to the portion where the connecting pipe 9 and the inlet pipe 5 are joined, opens the inlet pipe 5 at the inlet side and discharging side so that the inlet pipe 5 itself can have a straight line flow, simultaneously with the operation of the circulating pump 4.

Therefore, only the water in the outlet pipe 6'arranged indoors is circulated in the heating device 8 and indoors by the pumping operation of the circulating pump 4 and the circulating pipe 10, for thereby supplying a hot water of a high temperature instantaneously

and continuously. In such a circulating process, the hot water heated at a high temperature is discharged through the outlet pipe 6', and the hot water flowing along the outlet pipe 6' is continuously circulated along the outlet pipe 6', the heating device 8, the inlet pipe 5 and the circulating pipe 10 by the pumping operation of the circulating pump 4 and according to the opening state of the flow channel of the three-way valves 11 and 11', which is capable of automatic switching by a solenoid or motor.

Such a process for providing a hot water of a high temperature instantaneously is particularly proper for using hot water instantaneously for the purpose of indoor drying by means of rapid heating in a rainy season or nursing, especially, in the summer in which space heating and hot water are less used.

Additionally, when a midnight electric power is used simultaneously with the use of space heating and hot water, a temperature characteristic curve as shown in the following chart can be obtained. When a power is applied in the midnight power supply hours, the heater 7 in the heating device 8 and the heaters 3 and 3'in the heat storage tank 2 are simultaneously heated. The heat storage material in the heating device 8 having a relatively small heating volume is firstly heated. Thus, it is circulated for thereby enabling the use of instantaneous space heating and instantaneous hot water.

* Temperature characteristic curve of switching regenerative type midnight electric boiler Tempperature characteristic curve of switch ! ng regenerative type midnight electric bolier

Additionally, as shown in Fig. 5, when the power switch 20 is turned on and the indoor switch is turned off in the midnight power supply hours, simultaneously, the circulating pump 4 of the inlet pipe 5 is turned on. Then the three-way valve 11 is operated such that it can have a flow channel opening state in which the progression of water or latent heat material in the inlet pipe 5 is enabled. The three-way valve 11', which is mounted to the joint between the connecting pipe 9 and the inlet pipe 5, opens the flow channel so that water or latent heat material can be discharged directly to the inlet pipe 5 through the connecting pipe 9 without communicating with the outlet pipe 6'indoors.

Thus, the water or latent heat material is discharged through the heating device 8 in the heat storage tank 2. The water or latent heat material heated to a high temperature by the heating device is continuously circulated along the connecting pipe 9 and the inlet pipe 5 to thus continuously heat the water in the heat storage tank 2.

Additionally, as shown in Fig. 6, in the daytime in which a midnight power is not supplied and in the state where the midnight power is not supplied because the power is automatically cut off upon the completion of storage of the heat storage tank 2, when the indoor switch is turned on, the heat storage material in the heat storage tank 2 is circulated only by the operation of the circulating pump 4 formed in the inlet pipe 5. At this time, the three-way valves 11 and 11'are simultaneously operated, each of which being mounted to the joint of the inlet pipe 5 to which the circulating pipe 10 and the connecting pipe 9 are joined. With regard to the flow of fluid, by opening the flow channel in the direction where the body of the inlet pipe 5 is formed, the heat storage material, which is heated to a high temperature by the heaters 3 and 3'in the heat storage tank 2 and the heater 7 in the heating device 8, is circulated in the outlet pipe 6', the inlet pipe 5 and the heat storage tank 2 directed to the heating device and indoors.

The automatic control as shown in Figs. 4 through 6 is operated according to the automatic control circuit as shown in Fig. 7 (sequence diagram).

Therefore, space heating and hot water can be used instantaneously as needed by a user only by the heating device with a heater of a relatively small capacity and a simple construction for connecting it, and they can be continuously heated during midnight power

supply hours only by heaters of a relatively small capacity. Also, even though only one heater of a proper capacity, i. e., a small capacity was mounted, it is enough to use instantaneous space heating and hot water, for thereby reducing the overall size of the apparatus.

Furthermore, as shown in the following chart, the load factor of power consumption, which was concentrated in the midnight power supply hours conventionally, is greatly reduced, because a small capacity heater is used according to the present invention.

* Distribution Line Load Characteristic Curve of Switching regenerative type Midnight Electric Boiler Load factor * Distribution line load characteristic curve of switching regenerative type midnight electric bolier

That is, the storage performance of the conventional regenerative type midnight electric boiler and the switching regenerative type midnight electric boiler will now be examined as below.

[Example] House area: 30 Pyong (99. 294 m2), Midnight power: 30kw, Heat storage tank capacity: 2,700t

With regard to the quantity of water circulated in pipes required for boiler heating, the inner diameter of a hot water pipe is 15mm and the total length thereof is approximately 320mm, so the quantity of circulated water (t) equals to 7iD/4x320 = 3.14159x (0. 015) 2/4*320 = 0.0565 [m3] (D: diameter of pipe) Thus, the quantity of circulated water required for space heating is 56.5 (E).

1-1. Examination of Calculation of Heat Quantity of Conventional Storage Type Midnight Electric Boiler o Time required for increasing the temperature of water (2,700t) in the heat storage tank by one degree. C. by using a heater of 30 [kw].

Required Time T [h] = M [C (t2-tl) +g]/860xPx, u = 2,700/860x30 = 0.1046 [h] (T: time, M: mass of water, C: specific heat of water, t2 : temperature of water after heating, tl : initial temperature of water, g: latent heat of water, ll : efficiency) Thus, it takes 30 [°C] x 0.1046 [h] = 3.138 [h] to increase the temperature 60°C of water in the heat storage tank to 90 °C.

1-2. Examination of Calculation of Heat Quantity of Switching regenerative type Midnight Electric Boiler (T. S. C.) according to the present invention o Time required for increasing the temperature of water (56.5) in the heating device by one degree. C. by using a heater of 7 [kw].

Required Time T [h] = M [C (t2-tl) +g]/860xPxp = 56.5/860x7 = 0.00938 [h] That is, it takes 30x0. 00938 = 0.281 [h], i. e., approximately 16.89 minutes to increase the temperature of water (56. 5#) for use in space heating by the T. S. C. system 7kw. o Time required for increasing the temperature of water (2, 700#) in the heat storage tank by 30 ° C by using a heater of 8 [kw] in the heat storage tank.

Time Required for increasing by 1 °C T [h] = M [C (t2-tl) +g]/860xPxll = 2,700/860x8 = 0. 39 [h], thus it takes 30x0. 39 = 11.7 (h), which is the target temperature.

Therefore, in a case that the heater 7 [kw] in the heating device the switching regenerative type midnight electric boiler are simultaneously started up in a system of mutual circulation, water (2,700t) is heat-stored by instantaneously switching an insufficient heat storage time 1.7 (h) of the heater 8 [kw] in the heat storage tank to the heat

storage time of the heater 7 [kw] in the heating device whenever priority room heating is completed during 10 hours, thereby enabling a sufficient heat storage by using instantaneous space heating and hot water.

As known from the aforesaid resulting values, conventionally, it is disadvantageous in that since the heat storage material in the heat storage tank is heated instantaneously by using a heater of a large capacity, the load capacity thereof is concentrated in the time period of approximately 3 to 5 hours starting from the start time of the midnight power supply service. While according to the switching regenerative type midnight electric boiler of the present invention, it is possible to use instantaneous space heating and hot water and while accomplishing a continuous heating operation of the heat storage tank, thereby resulting in a uniform low load capacity throughout the midnight power supply hours.

Furthermore, it is not impossible at all to employ the exterior heating device of the invention to the regenerative type electric boiler being commonly used currently, the usefulness thereof is improved.

As described above, in the switching regenerative type midnight electric boiler and water heater with an exterior heating device according to the present invention, it is possible to use space heating and hot water instantaneously only by a heater of a small capacity even in the midnight power supply hours. In addition, cost can be reduced by employing a heater of a small capacity, the performance of existing midnight boilers can be improved, and investment cost can be reduced by sharing a midnight power load.