JPS6345826B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing a regenerative electric heater used as a local body heater or the like. Conventional technology Conventionally, when a heat storage element using a latent heat storage material and an electric heater are used in combination, a solid or liquid latent heat storage material is filled into a container, and then the mouth of the container is sealed under atmospheric pressure. element was used. Problems to be Solved by the Invention In this enclosing method, if the latent heat storage material is in the form of granules, if the latent heat storage material is filled using the usual method, air will be enclosed in a single block that will occupy more than 33% of the volume of the container. Become.
Furthermore, when heated, the air inside the container expands, further increasing its rate. If there is air in the heat storage element, heat will be transferred from the outside to the heat storage material through the air layer during heat storage, making it more difficult to transfer heat than when there is no air layer, and the heat storage will end. It will take a long time.
Also, as a matter of course, if air is enclosed in the heat storage element at the same time as the heat storage material, the heat storage density per unit volume of the heat storage element will be reduced. In addition, when the latent heat storage material is liquefied and sealed in a flexible container, if the container is sealed by reducing the air content, the fused layers will be brought together and the liquid will rise up to the fused area. It then sticks to those surfaces, making it impossible to adhere properly. Also, even if it appears to be sealed well at first glance, the adhesive layer will come off if a little external pressure is applied. In order to ensure fusion, it is unavoidable to simultaneously seal a considerable amount of air into the container, which naturally results in poor heat storage characteristics, similar to a heat storage element filled with granular latent heat storage material. Moreover, the heat storage density becomes low. In addition, if there is a part of the air in the heat storage element, there is a problem that almost no heat is transferred from the heater near the air to the heat storage material, and the temperature of the heater in that part becomes extremely high. . The present invention aims to solve these problems and provide a safe regenerative electric heater that has good heat storage characteristics, high heat storage density, and high heat storage density. Means for Solving the Problems The present invention is characterized in that a latent heat storage material is sealed in a flexible container under reduced pressure to create a heat storage element, and an electric heater is provided in close proximity to the heat storage element. Preferably, the air pressure when sealed is 1 mm.
From Hg to 200mmHg. Effects According to the present invention, the air interposed between the electric heater and the latent heat storage material can be effectively reduced, so that the heat transfer between the two is smooth, the heat storage properties are very good, and the heat storage element The heat storage density is also high because no air is sealed inside. Furthermore, since heat is uniformly transferred from the electric heater to the latent heat storage material, the risk of one part of the heater becoming overheated is extremely reduced. Examples Example 1 The latent heat storage material 1 shown in FIG. 1 is made of sodium acetate trihydrate with 2% by weight of sodium pyrophosphate added as an anti-supercooling agent, and the material of the storage container 2 is as follows: From the outside, 12μ
m polyester layer, 15 μm stretched nylon layer,
A laminate film consisting of four layers, a 9 μm aluminum foil layer and an 80 μm polyethylene layer, was used.
In the case of this laminate film, the fusing layer is the innermost polyethylene layer. Two pieces of this laminated film were put together and the necessary parts were heat-sealed to create a container with an internal size of 100 mm x 100 mm. This container was filled with 40 g of granular latent heat storage material and sealed under various atmospheric pressures as shown in Table 1 below. A planar electric heater 3 (controlled temperature: about 80° C.) having self-control characteristics was attached to one side of the heat storage element thus produced using adhesive tape. This regenerative electric heater was sandwiched between approximately 1 cm of polyurethane foam insulation and installed so that the heater surface was facing downward. The heat storage characteristics were evaluated by measuring the temperature at the center of the heat storage element on the opposite side of the heater using a thermocouple. Figure 2 shows the heat storage characteristics of Sample 2.
In this figure, the vertical axis is the temperature at the center of the heat storage element on the opposite side of the heater, and the horizontal axis is the elapsed time after the start of energization. As a guideline for the time required to complete heat storage, the elapsed time until the temperature of the heat storage element exceeds the transition temperature of the heat storage material and reaches 60°C was used. This time is indicated by an arrow in the figure. The time required to complete heat storage determined in this way is shown in Table 1 along with the air pressure at the time of sealing. Looking at this table, when the air pressure at the time of sealing is 100 mmHg or less, the time required to complete heat storage is almost constant, within 23 minutes, and when it is 300 mmHg, it takes 29 minutes. And for 760mmHg (atmospheric pressure)

[Table] *Sample 8 is a comparative example.
It takes 62 minutes to complete heat storage, approximately 170% longer than when sealed at 100 mmHg or less. By the way, in order to reduce the pressure, a vacuum pump is required, and in order to increase the degree of vacuum, it is necessary to perform suction for a long time. For vacuum levels of around 1mmHg, a regular rotary pump is sufficient.
In order to increase the vacuum level further, it is necessary to use a rotary pump for a very long time or to use it in conjunction with another vacuum pump. Naturally, this would increase the cost of the heat storage element and make it impractical. Therefore, from a practical standpoint, it is considered appropriate to seal under a pressure of 1 mmHg or more. So, in the end, the desired pressure range is from 1 mmHg.
It is in the range of 200mmHg. Example 2 As the latent heat storage material, a system in which 2% by weight of lithium fluoride was added as a supercooling prevention agent to sodium acetate trihydrate was used, and as the container material,
From the outside: 12μm polyester layer, 40μm polyethylene layer, 9μm aluminum foil layer, 150μm
A laminate film consisting of four polyethylene layers of m was used. In the case of this laminate film, the fusing layer is the innermost polyethylene layer. This laminate film was folded in half and the necessary parts were heat-sealed to create a container with an internal size of 100 mm x 100 mm. 40 g of a latent heat storage material sealed in a breathable bag was filled into the bag, and the bag was sealed under an air pressure of 10 mmHg. As an electric heater, a wire heating element whose surface is electrically insulated is placed 12μ from the outside.
A sheet was used which was sandwiched between a laminate film consisting of three layers: a polyester layer of m thick, an aluminum foil layer of 20 μm, and a polyethylene layer of 80 μm. This electric heater and the heat storage element were glued together using an epoxy adhesive to obtain a heat storage type electric heater of the example. A bimetallic temperature controller set at 80°C was attached to this heat storage type electric heater, and the heat storage characteristics were measured under the same conditions as in Example 1. The time required for heat storage was 25 minutes, which is almost the same as in Example 1. It showed the same characteristics. In addition, with the same configuration, but with the heat storage material sealed under atmospheric pressure, it took 70 minutes to complete heat storage. Effects of the Invention According to the method for manufacturing a heat storage type electric heater of the present invention, a heat storage element is created by sealing a latent heat storage material in a flexible container under reduced pressure, and an electric heater is provided closely to the heat storage element. It is possible to realize an extremely safe regenerative electric heater that has extremely good heat storage characteristics, high heat storage density, and no problem of localized overheating.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a regenerative electric heater according to an embodiment of the present invention, and FIG. 2 is a graph showing heat storage characteristics of the regenerative electric heater according to the present invention. 1... Latent heat storage material, 2... Storage container, 3... Electric heater.

Claims (1)

[Scope of Claims] 1. A method for producing a regenerative electric heater, in which a latent heat storage material is sealed in a flexible container under reduced pressure, and an electric heater is provided in close contact with the heat storage element. 2. The method for manufacturing a regenerative electric heater according to claim 1, wherein the air pressure when the latent heat storage material is sealed in the flexible container is in the range of 1 mmHg to 200 mmHg. 3. Claim 1 in which the electric heater provided in close proximity to the heat storage element is a planar electric heater.
A method for producing a regenerative electric heater as described in Section 1. 4. The method for manufacturing a heat storage type electric heater according to claim 1, wherein the electric heater is bonded to the surface of the heat storage element.