JPS59198685A - Heat accumulation type electric heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a regenerative electric heater used in a space heater or the like.

Conventional Structure and Problems The conventional latent heat storage method has a structure in which a latent heat storage material is stored in a heat storage tank or a heat storage container, and a heating source such as an electric heater is embedded in the latent heat storage material. This method poses problems with heat storage rate, heat radiation rate, and heat storage efficiency, and in order to solve these problems, measures have been taken such as using heat exchangers, fins, heat media, etc., or encapsulating latent heat storage materials. On the other hand, as a local heater for the human body, etc., electric heaters buried in insulation materials are commonly used, but this conventional electric heater requires a power cord at all times, which limits the spatial range of use of the heater. Its power cord length range was limited.

In recent years, there has been a demand for a heater that continues to have a heating function for a certain period of time even after the power to the electric heater is turned off, and this requires the development of a regenerative electric heater. However, adopting the above-mentioned conventional latent heat storage method as a heat storage method for such a heater has problems in terms of cost, weight, and flexibility depending on the purpose of use.

OBJECTS OF THE INVENTION The purpose of the present invention is to provide an electric heater for use in space heaters, heat insulators, etc., which uses a latent heat storage method and has high heat storage efficiency, low cost, and light weight, and is highly flexible depending on the purpose of use. be.

Structure of the Invention The basic structure of the present invention is a linear heating element, an inner tube containing the linear heating element, an outer tube installed on the outer periphery of the inner tube and sealed at the end, and an inner tube and an outer tube. The latent heat storage material is housed in the space created by the gap between the A structural feature of this regenerative electric heater is that the cross section in the direction perpendicular to the tube axis is the same at any part of the tube. With this configuration, all parts of the tubular heater can have uniform heat storage and heat radiation characteristics, and the heat storage efficiency can be increased. Unfortunately, the gap distance between the inner and outer tubes that should be designed is determined by the required heat storage (input) time, the power consumption of the linear heating element used, the thermal conductivity of the latent heat storage material, etc. When used for heating etc., it is usually desirable that it be 2 crn or less.

In this case, the time required for heat storage is practically required.
It will be within hours. Further, the length of the outer tube is appropriately determined depending on the required heat storage capacity. Furthermore, by using an inorganic hydrated salt with a constant melting/solidification temperature in the range of 30 to 100°C as a latent heat storage material, and using plastic material for the inner and outer tubes, the heat storage efficiency is high, the weight is low, and the weight is low. Moreover, it is possible to obtain a heat storage type electric heater characterized by flexibility.

Furthermore, the embodiment of the regenerative electric heater of the present invention has a spacer in the gap between the inner tube and the outer tube, but this spacer is for keeping the gap distance between the inner tube and the outer tube constant,
Preferably, the presence of the spacer fixes the position of the inner tube at approximately the center of the outer tube. As a result, all the latent heat storage materials can be uniformly melted (heat storage state) within the set heat storage (input) time, and the heat storage efficiency is 1.
It has the advantage of being able to approach the 00 level. This is because all the latent heat storage materials housed in the outer tube exist within the range of the gap distance between the inner tube and the outer tube, which is designed in advance according to the set heat storage time.

In addition, the spacer of the embodiment is a good thermal conductor and is in close thermal contact with the inner tube and the outer tube. As a result, during the heat storage process when the power is connected, the thermal energy supplied from the inner tube can be more quickly transferred to the latent heat storage material, while during the heat dissipation process after the power is turned off, the thermal energy stored in the latent heat storage material can be transferred to the latent heat storage material. There is an advantage that the heat can be rapidly transmitted to the outer tube through the spacer, which is a good conductor, and further to the heat medium or heating object in contact with the outer tube.

Furthermore, instead of the above-mentioned spacer, the inner tube can be improved by using an outer tube having recesses at appropriate intervals, or by using an inner tube having protrusions on the outer wall at appropriate intervals. It is possible to fix the tube and the outer tube so that the gap distance between them is kept constant, thereby increasing the heat storage efficiency. In particular, the former configuration has the advantage of low cost because it is only necessary to provide a recessed part by heat processing the outer tube, and in general, electric heaters are often U-bent; Example (1) A latent heat storage electric heater as shown in FIG. 1 was prototyped. 1
1 is a linear heating element, which is made of a copper alloy mesh wire with an electrically insulated surface, and has an outer diameter of 3 cm and a length of 40 cnI.
, a heater wire with a power consumption of 20 W was used. The surface of the linear heating element 11 was coated with polyvinyl chloride to a thickness of 0.5 mm, and this was used as the inner tube 12. Next, a pipe made of the same polyvinyl chloride with an inner diameter of 20 mm, an outer diameter of 23, and a length of 40σ is used as the outer pipe 13, and this plastic outer pipe 13
A plastic inner tube 1 with a built-in heater wire 11 inside.
2, one of the ends 15 of the outer tube 13 was sealed by thermocompression, and the inner tube 12 was fixed at the center of the outer tube 13. Next, the latent heat storage material 14 is filled into the outer tube 13 from the other end of the outer tube which is opened. The latent heat storage material 14 used here is sodium acetate trihydrate containing 1 weight percent of the supercooling inhibitor decahydrate salt of pyrophosphate. 150 g of this was weighed, melted at a temperature of 66° C., and then poured into the outer tube 13 from the open end of the outer tube 13. After waiting for this latent heat storage material 14 to cool and solidify, the outer tube 13
The open end 7 of the tube was sealed by thermocompression, and the inner tube 12 was fixed at the center of the outer tube 13. Through the above steps, a regenerative electric heater as shown in FIG. 1 was created.

The latent heat storage material 14 has a melting point of 58°C and a freezing point of 5.
At 3°C, the latent heat of melting and solidification is 60 ca.The average specific heat of a solid is 0.3 ca.The specific heat of a liquid is 0.7 at 179°C.
cal, it is now ℃. Therefore, when the outside air temperature is set to 20°C and the heat storage temperature level is set to 65°C, the heat storage capacity of this regenerative heater is the sum of the latent heat amount 91al and the sensible heat amount 2.57.
1.51 cal, and the heater power is 2oW, so the time required to store that amount of heat in an adiabatic state is about 40 minutes.

Next, this regenerative electric heater can be used as a heater for an electric foot warmer, which is one type of local heater. As a result of embedding this heat storage type heater in the heat insulating material of the foot warmer, when the power is turned on, the foot warmer enters a warm state (5.8W heat dissipation), and within 60 minutes after the power is turned on, the latent heat storage material 14 The temperature reaches the set temperature of 65℃, and even if the power is turned off at this point,
Thereafter, the heat retention state (5, sW heat dissipation) could be maintained for 140 minutes.

A conventional electric foot warmer (heater power is 568W for comparison) can maintain heat retention (heat radiation of 6.8W) when the power is turned on, but rapidly loses its heat retention function when the power is turned off. On the other hand, when the heat storage type electric heater (heater power 20 W and heat storage capacity 11.51 cal) of the embodiment of the present invention is used, the heat retention function can be maintained even after the power is turned off. Moreover, this storage type electric heater is lightweight (less than 2ooy),
It is low cost and highly practical.

Example (2) A latent heat storage electric heater as shown in FIG. 2 was prototyped. 1
1 is a linear heating element, the same linear heating element 11 as in Example (1) (however, the length is 200 cm, the power consumption is 1oo)
W) was used. The surface of the linear heating element 11 was coated with polyvinyl chloride to a thickness of 0.6 mm, and this was used as the inner tube 12. 16 is a spacer, here the inner tube 12
In order to maintain a constant gap distance of 5.5M between the outer wall of the outer wall and the inner wall of the outer tube 13, the inner tube 12 containing the linear heating elements 11 was passed through the four holes, and 24 linear heating elements were inserted at an interval of 8 crn. The spacer was fixed to the outer wall of the inner tube 12 using an adhesive. Next, a polyvinyl chloride pipe made of the same material as the inner pipe 12,
Inner diameter 15M, outer diameter 17 gates, length 200 cm, 13 outer tubes
And so. After passing the inner tube 12 to which the spacer 16 has already been fixed into the outer tube 13, one end 1 of the outer tube 13 is inserted.
5 was sealed by thermocompression. Next, the latent heat storage material 14 is filled into the outer tube 13 from the other open end of the outer tube 13. Latent heat storage material used here 14. is the same as that used in Example (1).

The filling amount was 400.9, and after filling it in a molten state (65° C.) as in Example (1), the open end of the outer tube 13 was sealed by thermocompression. Through the above steps, a regenerative electric heater shown in FIG. 2 was created. Therefore, the outside temperature 5
℃, and the heat storage temperature level is set to 65℃, the heat storage capacity of this regenerative heater is 241 cal of latent heat and 8.5 cal of sensible heat.
7, the sum is 32.51 cal, and the heater power is 100
'Vψ, the time required to store that amount of heat in an adiabatic state is about 23 minutes.

Next, this regenerative electric heater can be used as a heater for an electric vest, which is one type of local heater. As a result of embedding this heat storage type heater in the insulation material of the vest, when the power is turned on, the vest enters the heat insulation state (20W heat radiation), and within 30 minutes after the power is turned on, the temperature of the latent heat storage material reaches 65% of the set temperature. ℃ and even if the power was cut off at this point, the heat retention state (20W heat dissipation) could be maintained for 100 minutes.

Conventional electric vest (heater power is 20V for comparison)
) can maintain heat retention (20W heat dissipation) when the power is turned on, but rapidly loses its heat retention function when the power is turned off. On the other hand, if the heat storage electric heater of this embodiment (heater power 1oOW 1 heat storage capacity 32.5kal) is used, the heat retention function can be maintained even after the power is turned off. In other words, a power cordless system can be achieved. Moreover, this regenerative electric heater is relatively lightweight (500 fl or less), low cost, and highly practical. \Example(
3) In the regenerative electric heater of Example (2), only the material of the spacer 16 shown in FIG. 2 was changed to a good thermal conductor made of a metal-plastic composite material. As a result, the difference between the outer wall surface temperature of the inner tube 12 and the outer wall surface temperature of the outer tube 13 was smaller than in Example (2). Due to this effect, the safety of the linear heating element 11 coating the inner tube 12 is improved, and at the same time, the heat dissipation from the outer surface of the outer tube 13 becomes faster when power is input. Example (4) A latent heat storage electric heater as shown in FIG. 3 was prototyped. 1
1 is a linear heating element, and the same one as in Example (2) was used. The surface of the linear heating element 11 was coated with polyethylene to a thickness of 0.5 mm, and this was used as the inner tube 12. Next, a polyethylene pipe made of the same material as the inner tube 12, having an inner diameter of 15 mm, an outer diameter of 17 mm, and a length of 220 crn was used as the outer tube 13. After passing the inner tube 12 into this outer tube 13,
One end 15 of this outer tube 13 was sealed by thermocompression. Next, the latent heat storage material 14 was filled into the outer tube 13 from the other open end of the outer tube 13 in the same manner as in Example (2). The latent heat storage material 14 used was exactly the same as that used in Example (2), but its filling amount was 360 g. Next, by heat processing, a hollow portion 1γ is formed in the polyethylene outer tube 13.
were made at intervals of 10C1n. The average length of the recessed portion 17 is 1α, and the inner wall of the outer tube is not in close contact with the outer wall of the inner tube 12 at this recessed portion 17.

In addition, during this thermal processing, the temperature of the latent heat storage material 14 is always kept at 6.
It is necessary to maintain the temperature between 5° and 70°C. After creating the recessed portion 17, the open end of the outer tube 13 was sealed by thermocompression. Through the above steps, a regenerative electric heater shown in FIG. 3 was created.

The power consumption of this heat storage electric heater is 100W.

The heat storage capacity is 30 m], and similarly to Example (2), it can be used as a heater for an electric vest.

Compared to Example (2), this heater has advantages such as faster heat dissipation upon power input and lower manufacturing cost. Example (6) Latent heat as shown in Figure 4 We prototyped a regenerative electric heater. 1
1 is a linear heating element, and here a sheathed heater with a power consumption of 1.5 KW made of nichrome wire electrically insulated with magnesia powder was used. The Inconel pipe of this sheathed heater corresponds to the inner pipe 12. The outer diameter of this sheathed heater (corresponding to the outer diameter of the inner tube 12) is 6 mm, and its length (corresponding to the length of the inner tube 12) is 130 m.13 is the outer tube, and the inner diameter is 130 m. The pipe is made of Inconel, which is the same material as the pipe 12, and has an inner diameter of 40 mm, an outer diameter of 42 cm, and a length of 13 ocrn.After passing the inner pipe 12 through the outer pipe 13, one of the outer pipes 13 is The end portion 15 was sealed by welding.Next, the latent heat storage material 14 was filled into the outer tube 13 from the other open end of the outer tube 13.The latent heat storage material 14 used here
4 is NaCt. Weighed 2300g of this and weighed 850g.
After melting at a temperature of .degree. C., it was poured into the outer tube 13 from the open end of the outer tube 13. Next, while maintaining the molten state of NaCL, the Inconel outer tube 13 was heat-processed to form three recesses 17 in the outer tube 13, as shown in FIG. The length of one of the recesses 17 is 10 m.

The inner wall of the outer tube at this recessed portion 17 is not in close contact with the outer wall of the inner tube 12. After creating the concave portion 17, the open end of the outer tube 13 was sealed by welding. Through the above steps, a regenerative electric heater shown in FIG. 4 was created. The melting/freezing point of this latent heat storage material is 800°C, and the amount of latent heat is 117 cal:/f.
l, and the average specific heat of the solid is 0-226 cal/Ii°C. Therefore, if the minimum temperature for heater operation is set at 100°C and the maximum temperature (corresponding to the heat storage temperature) is set at 850°C, the heat storage capacity of this regenerative heater is the amount of latent heat of 2697 and the amount of sensible heat of 45.
07, and the heater power is 1.5 KW, so the time required to store that amount of heat in an adiabatic state is about 35 minutes.

Next, the communicative electric heater can be applied to an electric fire pit, which is a type of local heater, or to a cooking/warming device. For example, when used as a heat source for an electric fire pit, install this heat storage type heater inside the heat insulation material of the fire pit, and when the power is turned on, the fire goes into the heat retention state (400W heat radiation), and when the power is turned on, In 46 minutes, the temperature of the latent heat storage material reached the set temperature of 850° C.4, and even if the power was cut off at this point, the heat retention state (400'W' heat dissipation) could be maintained for 120 minutes.

In this way, the electric fire pit using the regenerative electric heater of this embodiment has a heat retention function for several hours even after the power is turned off.

Therefore, if you disconnect the power cord while using a fire pit,
You can freely move it to another location and use it as a large drumstick for a while.

However, this thermal storage type electric heater can be used as a heater for cooking and warming devices (
For example, after using it for cooking in the kitchen, it can be removed from the power cord and moved to a guest room to keep the food warm for a while.

Effects of the Invention The structure of the heat storage type electric heater of the present invention allows short-term heat storage (
(e.g. within 1 hour), long-term heat dissipation (e.g. over 1 hour)
Moreover, uniform heat storage and heat radiation characteristics can be obtained in each part of the heater, and a heater with high heat storage efficiency can be obtained. Further, the configuration of the present invention provides a highly flexible, lightweight, and low-cost heater depending on the material used therein, and when used as a heater for a local heater, etc., it can be made cordless.

[Brief explanation of drawings]

1, 2, 3, and 4 are sectional views showing embodiments of the regenerative electric heater of the present invention, and FIG. 5 is a sectional view of the spacer. 11... Linear heating element, 12... Inner tube containing the linear heating element, 13... Accommodating latent heat storage material provided on the outer periphery of the inner tube. Outer tube, 14... Latent heat storage material, 15...- Sealed outer tube end, 1
6...Spacer provided in the gap between the inner tube and the outer tube, 1
7... Concave part of the outer tube. Name of agent: Patent attorney Toshio Nakao and one other name
1 Part 20 3 Figure 84

Claims (5)

[Claims] (1) A regenerative electric heater in which a latent heat storage material is stored in the gap between an inner tube containing a linear heating element and an outer tube provided on the outer periphery of the inner tube, and the ends of the outer tube are sealed. (2) The regenerative electric heater according to claim 1, wherein a spacer is provided in the gap between the inner tube and the outer tube. (3) The regenerative electric heater according to claim 2, wherein the spacer is a good thermal conductor and is brought into close contact with the inner tube and the outer tube. (4) The regenerative electric heater according to claim 1, wherein the outer tube has recessed portions at appropriate intervals. (5) The regenerative electric heater according to claim 1, wherein the inner tube has protrusions on its outer wall at appropriate intervals.