JP2501876B2 - Constant temperature heater - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a constant temperature heater, and more particularly to a constant temperature heater utilizing the principle of condensation heat transfer.

(Prior art) To keep the temperature of the heating element constant, use a temperature sensor to turn on / off the operation of the heating element, or use a heating element whose heat generation capacity changes according to the temperature. It is possible to make it self-controlled. Then, in the former case, the set temperature can be changed by moving the switching point of the on / off operation, but the control system such as the conventional electric heater is controlled by the control target and the temperature detection unit. Since it is composed of the adjusting section and the operating section, a complicated circuit is required to perform strict temperature control, and there is a drawback that the maintenance and the cost are expensive. On the other hand, in the latter case, since the temperature characteristics of the ceramic semiconductor heater, which is a heating element, are constant, it is practically impossible to change the set temperature according to the purpose of use.

(Problems to be Solved by the Invention) The applicant of the present patent application is Japanese Patent Application Laid-Open No. 63-
No. 299721), we proposed a constant temperature heater with self-temperature control using water / lipophilic fluid emulsion. This is a heat-generating medium that is made by adding a water-soluble electrolyte and an emulsifier to an emulsion of water or a hydrophilic fluid and a lipophilic fluid.
Resistance heat is generated by energizing the mold emulsion.
At a predetermined temperature, this emulsion phase-inverts to a non-conductive W / O type and is switched off, heat generation stops and temperature rise stops, so it functions as a constant temperature heater.

However, it has been found that such a constant temperature heater has the following problems when it is enlarged.

(1) In the above constant temperature heater, the electrode member is extended over the entire heating portion, so that the manufacturing cost thereof is relatively high.

(2) The amount of emulsion used is large, and the cost is high, so that it cannot be said to be efficient. Further, since the heat transfer is thermal convection and the heat transfer rate is comparatively small, it is necessary to install the electrode members as close as possible to the heater heating surface and densely.

(3) Insulating material such as resin must be used for the heater heat transfer section, and when metal is used for the heat transfer section, an insulating material must be coated, but in the former case, heat transfer is reduced. However, in the latter case, the cost will increase.

(4) The whole emulsion is a heating element, and when considering a large apparatus, a strong support mechanism for supporting it is necessary.

Therefore, it is required to further simplify the constant temperature heater as described above, which is mechanically relatively simple, and make it inexpensive so that it can be easily used in many fields.

An object of the present invention is to provide a constant temperature heater which is inexpensive and simple.

Another object of the present invention is to provide a constant temperature heater having a simple structure and excellent self-temperature controllability in terms of thermal efficiency.

Still another object of the present invention is to provide an inexpensive constant temperature heater which is large in size and has a large capacity.

(Means for Solving the Problem) The inventors of the present invention have made various studies aiming at solving the above-mentioned object, and have focused on applying the principle of condensation heat transfer in a conventional heat pipe, particularly in a thermosiphon type heat pipe. Then, various experiments were repeated to arrive at the present invention.

It should be noted that any type of conventional heat pipe is understood as a heat transfer means for transferring heat from one location to another location, and is understood as a heating source itself such as a heating heater. It has not been done, and the two have completely different ideas. Therefore, even though the heat pipe may be placed in the heating area, there should be no idea that the heating device is incorporated in the heat pipe to be used as the heater.

Here, the gist of the present invention is that it is composed of a heat radiating portion whose inside is decompressed and a heating portion connected to one end of the heat radiating portion so that gas can flow freely, and the heating portion is protected from water or hydrophilic fluid. Water or hydrophilicity that heats up by applying current and exhibiting a phase inversion phenomenon in which a conductive O / W type emulsion undergoes a phase inversion at a set temperature consisting of an emulsion of an oily fluid and a water-soluble electrolyte and an emulsifier. A constant temperature heater that contains an oleophilic / lipophilic fluid emulsion and that has at least two opposing electrode members that are immersed in the emulsion, and an inner wall surface of a heat radiating portion that condenses and transfers the gas evaporated from the emulsion. is there.

(Operation) Next, the present invention will be described in more detail with reference to the accompanying drawings.

As shown in the schematic explanatory views in FIGS. 1 and 2, a constant temperature heater 10 according to the present invention is composed of a heating section (evaporating section) 11 and a heat radiating section (condensing section) 12, and the heating section 11 has a switching function. Contains emulsion 13 with characteristics,
Inside thereof, at least two electrode plates 14 are provided so as to be opposed to each other at an appropriate interval, and heat is generated from the emulsion by energization from the electrode plates. As the emulsion as the heat generating medium, the emulsion having the composition described in detail in the above publication can be used as it is.

That is, a preferred composition example of the above-mentioned water / lipophilic fluid emulsion is as follows.

The oil used in the present invention is not particularly limited as long as it exhibits electric insulation due to the properties of the present invention and easily forms a mixed emulsion with water,
For example, hydrocarbon oils (eg benzene, cyclohexene,
Examples thereof include normal heptane), fats and oils (eg animal and vegetable fats and oils containing fatty acid glyceride as a main component), and paraffinic mineral oils.

The mixing ratio of oil and water is not particularly limited, but from O / W type to W
To facilitate phase inversion to the / O form, the oil: water ratio is 5: 1 to 1: 5, with approximately 1: 1 preferred.

Although water is used as the hydrophilic fluid in this specification for convenience of description, it goes without saying that another hydrophilic fluid may be used to form an emulsion with the lipophilic fluid.

Here, the nonionic surfactant used as an emulsifier of the emulsion preferably has an ethylene oxide group, and (1) ether type includes alkyl and alkylallyl polyoxyethylene ethers and polyoxyethylene polyoxypropyl Alkyl ether, etc.
(2) The ether ester type includes polyoxyethylene ether of glycerin ester, polyoxyethylene ether of sorbitol ester, etc., and (3) the ester type includes polyethylene glycol fatty acid ester,
Examples of the sorbitan ester and the like (4) nitrogen-containing type include polyoxyethylene alkylamine and polyoxyethylene fatty acid amide.

Such a nonionic surfactant, relative to the total weight,
1 to 40% by weight, preferably 5 to 20% by weight is added.

The electrolyte that imparts conductivity is added in order to adjust the electrical resistance of the aqueous phase, that is, to control the heat generation amount and to change the phase inversion temperature, in other words, an alkali metal salt such as NaCl or KCl, Na ₂ There are carbonates such as CO ₃ and sulfates such as Na ₂ SO ₄ ,
In addition, an organic salt such as sodium acetate or an ionic surfactant may be used. However, the electrolyte must be soluble only in one phase of the emulsion, the aqueous phase. This is because when the compound dissolves in both, the change in conductivity due to phase inversion disappears and the emulsion cannot have a self-controlling function. The amount of such an electrolyte added is generally such that the specific resistance in the O / W type emulsion is 10 to 100.
It is preferable to set it to about 00 Ωcm. Conductive O /
The phase inversion temperature from the W type emulsion to the non-conductive W / O type emulsion, that is, the set temperature of the constant temperature heater according to the present invention, is changed by changing the composition of the electrolyte and the emulsifier to the emulsion composition, It can be easily changed by changing the amount.

The specific shapes and dimensions of the heating unit 11 and the heat radiating unit 12 are not particularly limited, and for example, the heating unit and the heat radiating unit may be entirely formed of an upright cylindrical body, or the heat radiating unit may be horizontal and only the heating unit may be vertical. Good. The insulating layer 18 is provided in the heating section in order to electrically heat the emulsion contained therein, but it is not necessary in the heat radiating section. Further, it is not necessary to make the heat radiating portion and the heating portion have the same diameter, and for example, a multi-tube heater as shown in FIG. 2 can be manufactured. The constant temperature heater 10 shown in FIG.
A plurality of heating tubes 20 are provided at the upper end of the heating unit 11 composed of a wide-mouthed container.
A heat radiating portion 12 made up of (three in the illustrated example) is connected. In the figure, the same reference numerals as in FIG. 1 indicate the same members.

As described above, according to the present invention, it is sufficient that the vapor gas can move from the heating unit to the heat radiating unit. Therefore, it is sufficient that the heating unit is connected to one end of the heat radiating unit so that the gas can flow therethrough.

There is a certain correlation between the evaporation amount of water, that is, the surface area of the bath and the outer surface area of the heat radiation part. Therefore, in order to increase the size of the constant temperature heater, it is necessary to secure a sufficient amount of evaporation, and for that purpose, a wider heating section must be used. But,
As will be described later, in the case of the present invention, since the load responsiveness is excellent, it is possible to secure the evaporation amount according to the load even with a constant evaporation area, and therefore it is possible to easily increase the size to match it.

A heat radiating portion 12 as a main body of a heat generating heater portion is provided above the emulsion 13 bath, and the whole is hermetically sealed and the inside thereof is depressurized to a pressure of 10 Torr. Or less, for example. A plurality of heat dissipating fins 15 are provided on the outer side of the heat dissipating portion 12 to increase the heat dissipating area. The heat radiating section including the fins is preferably made of a metal having good thermal conductivity, such as copper or aluminum.

Reference numeral 16 indicates a power source. Since the emulsion 13 is electrically heated, either alternating current or direct current may be used, but alternating current is simple. When the heater 10 is energized by passing a current from the power source 16, bubbles are generated as the emulsion 13 is heated by Joule heat, and water is evaporated from the emulsion surface. The generated water vapor moves to the upper portion where it is cooled by the vapor pressure, enters the heat radiating portion 12 connected to the heating portion 11, and is condensed on the inner wall surface 17 of the heat radiating portion to become water. During this time, latent heat of vaporization is transferred to the inner wall surface 17 of the heat radiating portion through the action of evaporation-condensation. The condensed water returns to the lower heating unit 11 along the pipe inner wall forming the heat dissipation unit inner wall surface 17. The returned water is uniformly mixed in the emulsion 13 in a boiling state and then heated again to generate steam. Then, the above process is repeated again.

The return of the condensed water to the evaporation part may be performed by dropping the inner wall surface 17 of the heat dissipation part by gravity as described above, but like a heat pipe, a wick is provided on the inner surface of the wall to prevent capillary action. You may utilize and return to an evaporation part. Many other modifications are possible. The specific contents of these structures are already apparent to those skilled in the art from the above description,
Further description is omitted for brevity.

As described above, according to the present invention, the following advantages can be considered as compared with the conventional electric heater and the conventional constant temperature heater.

Since the amount of steam generated can be adjusted according to the load, it has self-controllability. The conventional electric heater cannot control the temperature unless a control device is provided. Moreover, the responsiveness is higher than that of the conventional constant temperature heater.

By changing the composition of the emulsion, the temperature of the heat radiating part (aggregating part) can be arbitrarily set.

The electrode part, which occupies a large weight in the constant temperature heater, can be reduced to about 1/10 in comparison with the same heater length, so a considerable cost reduction can be expected.

No special measures are required to absorb the thermal expansion of the emulsion.

Since the transfer of heat is due to the latent heat of vaporization, the heat transfer coefficient is very large, and a large amount of heat can be transported with a small temperature difference.

Since the inner surface of the heat transfer section is only used for the circulation of steam, there is no need to apply an insulating material even when a metal is used, so no extra cost is required, and heat transfer is efficiently performed.

Even when the emulsion is in a non-uniform state at the time of starting, since the stirring action can be obtained by the generation of bubbles, the emulsion can always be used in a uniform state.

Larger size, that is, a large capacity constant temperature heater can be easily manufactured.

Next, the present invention will be described in more detail by way of examples.

Example Using the constant temperature heater device according to the present invention shown in FIG. 1, the effect of the present invention was confirmed.

First, in FIG. 1, the heat radiating portion was composed of a copper cylindrical body having a diameter of 25 mm and a total of 40 fins provided at 1 cm intervals. The inner surface of the heating part was glass-lined for insulation. Twelve electrode plates were prepared, six each, and they were installed facing each other. The depth of the heating part containing the emulsion was 40 mm.

The composition of the emulsion used in this example and the set temperature as a constant temperature heater in that case are shown in the following table.

However, the nonionic surfactants 1 and 2 have different compositions.

The results are shown graphically in FIG. Curve No. in the graph
Is the same as No. 1 in Table 1. It can be seen that a constant temperature is maintained for each fin at any set temperature. 8
Even at the high temperature setting of 6.5 ℃, the constant temperature range was 30 out of 40 steps, which was about 75%, and the constant temperature characteristics were maintained. See curve No.2. When the set temperature becomes lower, the constant temperature maintaining characteristic of each fin is improved, and the maintained constant temperature becomes closer to the set temperature.

FIG. 4 is a graph showing a change in output with respect to the wind speed when wind is applied to the fins from the outside and a load is applied. It can be seen that the output increases with the load. No. in the graph corresponds to that in Table 1. As the output (W), that is, the power consumption increases, the amount of evaporation also increases, so it can be said that the capacity is larger. In other words, in the case of No.2 emulsion,
In the case of 3.5 times and No. 1, it means that the output can be increased by about 2.7 times. In other words, when there is no load, it can be operated with a margin.

From these results, it can be seen that the constant temperature heater according to the present invention can effectively exhibit the self-temperature control characteristic.

(Effects of the Invention) As described in detail above, according to the constant temperature heater of the present invention that skillfully uses heat transfer condensation, the constant temperature heater according to the present invention is caused by the expansion of the emulsion, which is a problem of the conventional apparatus, by a very simple means. Defects such as destruction of the sealing device, large amount of emulsion required, high cost of electrode members, insufficient heat transfer, etc. are effectively eliminated, and the emulsion is always used in a uniform state by boiling and stirring. Therefore, the constant temperature heater can be put into practical use.

The constant temperature heater according to the present invention can set a temperature of 30 to 80 ° C., for example, and can be used as a heater for reheating inside a duct and a heater for heating soil. Considering its low cost and simplicity, many other application examples are possible.

Therefore, the present invention is convinced that the invention can be sufficiently patented from the above practical advantages that could not be considered only by heat transfer by conventional heat transfer condensation.

[Brief description of drawings]

1 is a schematic explanatory view of a constant temperature heater according to the present invention; FIG. 2 is a schematic explanatory view of another embodiment of a constant temperature heater according to the present invention; and FIGS. 3 and 4 are embodiments. It is a graph which shows the result of. 10: constant temperature heater, 11: heating part 12: heat dissipation part, 13: emulsion 14: electrode plate, 15: fin 16: power supply, 17: inner wall surface 18: insulating layer

Claims (1)

(57) [Claims] 1. A heat-radiating portion whose inside is depressurized and a heating portion which is connected to one end of the heat-radiating portion so that gas can freely flow therethrough,
A water-soluble electrolyte and an emulsifier are added to an emulsion of water or a hydrophilic fluid and a lipophilic fluid in the heating section, and the conductive O / W emulsion is phase-inverted to a non-conductive W / O emulsion at a set temperature. At least 2 pieces of water, which exhibits a phase inversion phenomenon and generates heat when energized, or which contains a hydrophilic fluid / lipophilic fluid emulsion and is immersed in the emulsion.
A constant temperature heater having two opposing electrode members and a heat radiating portion inner wall surface where the gas evaporated from the emulsion transfers heat by condensation.