JPS5849850A - Water heater utilizing latent heat type heat accumulating material - Google Patents

Abstract

PURPOSE:To enhance the heat exchange efficiency of the heater by a method wherein the heater comprises sealing the latent heat type heat accumulating material and working liquid, the specific gravity at the melting point of which is larger than that of the heat of the heat accumulating material within the heater. CONSTITUTION:The latent heat type heat accumulating material 2 and the working liquid 3, the specific gravity at the melting point of which is larger than that of the heat accumulating material in the molten state, are sealed within the case 1 of the water heater, at the lower part of which a heater 5 is provided and at the upper part of which a heat exchanger 4 is provided. As an example, sodium acetate trihydrate is employed as the heat accumulating material and Freon R-113, which is non-compatible and non-reactive with sodium acetate trihydrate, is used as the working liquid.

Description

[Detailed description of the invention] The present invention relates to a water heater using a latent heat type heat storage material.

Traditionally, inorganic salts have been used as heat storage materials that utilize latent heat.

Organic or paraffin materials have been used, but one of the problems in either case is that heat exchange does not take place quickly. In the molten state, the temperature line in the heat storage material becomes uniform due to convection, but once it begins to solidify, the heat transfer from the surroundings decreases due to the poor heat transfer of the solid, and the temperature of the heat storage material near the heat exchanger decreases. decreases rapidly. That is, near the heat transfer surface, the heat storage material releases its latent heat and solidifies. When solidified, thermal conductivity is poor, making it difficult to transfer heat from the molten heat storage material near the solidified heat storage material to the heat transfer surface. Therefore, the heat storage material is in a solid phase near the heat transfer surface, and remains in a liquid phase a little further away.

It took a long time to effectively utilize the latent heat of the liquid phase. In actual use, various methods are taken to prevent the above phenomenon from occurring. For example, methods include adding fins to heat transfer tubes to shorten the distance between the heat transfer surfaces and making it difficult for liquid phase to remain between the heat transfer surfaces, but this has not actually solved the above problem. .

Further, when heat is stored in the heater, the heat storage material after releasing the heat is solid and remains attached to the heater. When the heater is energized, the heat storage material melts, but because the temperature near the heater increases faster than the melting speed, there is a risk that abnormally high temperatures will occur and the heat storage material will thermally decompose. Therefore, installing the heater on the outside of the water heater case is necessary to prevent the above-mentioned problems from occurring, but new problems have arisen in that the heat utilization efficiency is lowered and the heat storage time is increased.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a water heater that can perform heat exchange quickly and efficiently, and can also be made small in volume.

The basic structure of the present invention includes a latent heat type heat storage material, a heat exchanger for extracting heat to the melting temperature of the material, and a heater for supplying heat into the heat storage material. This configuration allows heat to be exchanged quickly and efficiently without creating a solid phase with poor heat transfer around the heat transfer surface of the heat exchanger when extracting heat.

Specifically, in the gate case 1 there is a heat storage material 2 and a working fluid 3 whose specific gravity is greater than that of the heat storage material in the molten state.
Further, a heat exchanger 4 is provided in the gas phase portion of the upper layer of the heat storage material to extract heat, and an electric heater 6 is provided in the heat storage material to supply heat. 6,
7 is the piping of the heat exchanger. However, a part of the heat exchanger 4 may be immersed in the heat storage material. In this case, the heat storage material and the working fluid are non-reactive and immiscible. When the heat storage material is in a molten state, the temperature inside the tank is equal to the melting temperature of the heat storage material and the liquid phase mainly composed of the heat storage material. It consists of a gas phase that is in equilibrium with the vapor pressure of the working fluid.

A heat exchanger 4 is provided in this gas phase.

In order to extract heat to the outside, a low-temperature heat medium is introduced through the pipe 6, and the vapor of the working fluid releases its heat through the heat exchanger and is condensed and liquefied. When condensed and liquefied, the vapor pressure of the gas phase decreases. This is compensated for by the working fluid vapor rising in the form of bubbles 8 in the heat storage material. At this time, the bubbles exhibit the same effect as stirring the heating material and make the temperature distribution uniform.

Further, the condensed working fluid has a higher specific gravity than the heat storage material in the molten state, so it settles. At this time, some of it absorbs heat from the heat storage material and vaporizes again, and the vapor rises in the form of bubbles. The other part settles to the bottom of the heat storage tank and forms three reservoirs of working fluid.

This working fluid absorbs heat from its surroundings and vaporizes again, forming bubbles 10 and rising up to the heat exchanger. On the other hand, the low-temperature heat medium in the form of driftwood from the pipe 6 receives heat in the heat exchanger, becomes a high-temperature heat medium, and flows out from the pipe 7. In this way evaporation and condensation of the working fluid can be achieved.

Furthermore, when electricity is applied to the heater to store heat, there is a solid heat storage material around the heater, which is melted by the heat of the heater. In the present invention, since a working fluid with a specific gravity larger than that of the heat storage material is used, the working fluid absorbs heat near the heat exchanger and vaporizes, forming bubbles and moving through the molten heat storage material. heat is applied to dissolve it and the working fluid itself condenses.

This movement of the working liquid vapor is also carried out through minute paths created by bubbles of the working liquid when the heat storage material solidifies, so this movement is carried out to a considerable distance from the heater. In the above process, as the heat storage material is agitated by air bubbles, an abnormally high temperature is generated near the heater and the heat storage material is decomposed.
There will be no more.

It is possible to significantly increase the efficiency of visceral exchange, which makes it easier to remove heat from the medium. The working fluid mentioned in the present invention is a fluid that has a low melting point and absorbs heat from others, such as fluorocarbons and alcohols.

There are ketones, etc.

The details of one embodiment of the present invention will be explained.

Does it work with sodium acetate trihydrate (NaCH3Coo-sH20) as a heat storage material? L! :I, -c
Freon R is incompatible and non-reactive with sodium acetate trihydrate
-113 is sealed in a heat storage tank, and non-sulfur such as air is discharged. The density of sodium acetate trihydrate at its melting point (6B ''C) is 1.34 P/cyll, Furoy R-' 11
The density of No. 3 at the same temperature is 1.46 f/ul.

, Therefore, if you run cold water as explained above, R
-113 condenses in the heat exchanger, drips, and settles in the heat storage material.
Re-evaporate under heat from sodium acetate trihydrate solution. By repeating this evaporation-condensation cycle, the water salt releases latent heat, becomes microcrystalline, and accumulates from the bottom of the water heater. Therefore, all the latent heat that sodium acetate trihydrate has can be effectively utilized. Furthermore, it was confirmed that even if the heat storage material was directly heated by a heater during heat storage, the heat storage material was not abnormally heated due to the heat transfer action of Freon R-113.

As described above, according to the water heater of the present invention, the following:
::274,8□,5゜2. ,. 7, no solid phase portion with poor heat transfer is generated around the heat transfer surface of the heat exchanger, so heat exchange can be performed easily and quickly.

2 As the vapor of the working fluid passes through the heat storage material in the form of bubbles, the heat storage material is stirred by the bubbles, the temperature distribution of the heat storage material is uniform, and solidification occurs from a certain point. do not have. In addition, the solidified heat storage material has a higher specific gravity than when it is in a molten state, so it settles, but in this case, because it is stirred by the air bubbles in the heat storage material, it becomes fine crystals and is deposited at the bottom of the heat storage tank. To go. That is, the heat storage material that has released latent heat gradually sinks to the bottom. Therefore, the latent heat of the entire heat storage material can be effectively utilized.

3 Even if the heat storage material solidifies, the working fluid does not solidify.

Furthermore, since the path created by the vaporization of the working fluid exists in the form of open bubbles in the solidified heat storage material, the sensible heat of the heat storage material can also be utilized by the vapor of the working fluid passing through the bubbles.

4. Since the heater is inserted into the heat storage material, all of the heat from the heater can be effectively transferred to the heat storage material. In addition, since the actuating rod removes heat more quickly than the heater and gives heat to the unmelted heat storage material while stirring the molten heat storage material, the area around the heater does not become abnormally high temperature and thermally decompose the heat storage material.

[Brief explanation of the drawing]

The drawing is a sectional view showing an embodiment of the water heater according to the present invention. 1... Water heater case, 2... Heat storage material,
3... Working fluid, 4... Heat exchanger,
6... Electric heater.

Claims (1)

[Claims] The specific gravity of the latent heat type heat storage material and the heat storage material at their melting temperature is
A working fluid having a specific gravity greater than that of the heat storage material at that temperature is sealed in a case, and a heat exchanger is provided for extracting heat to the gas phase in the upper layer of the heat storage material, and the heat is supplied to the heat storage material. A water heater using a latent heat storage material and equipped with a heater.