JPS6037394B2 - Heat storage method and heat storage tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat storage method and a heat storage tank using the same.

More specifically, this invention dehydrogenates two types of hydrides of metals or alloys that can be dehydrogenated on a high temperature side and a low temperature side using the heat of a heat exchange medium that has been collected in advance, and uses the hydrogen produced by this dehydration. After storing the hydrogen, when it is desired to utilize the heat, the metal or alloy that can be hydrogenated at a low temperature produced by the dehydrogenation reaction is hydrogenated with the stored hydrogen to generate heat, and this heat is used to generate the hydrogen produced by the dehydrogenation reaction. A heat storage method characterized in that a metal or an alloy that can be hydrogenated at a high temperature is brought to a hydrogenation-enabled temperature and then hydrogenated with the stored hydrogen to utilize a larger heat of reaction, and a heat storage tank using the same. . Conventionally, various heat storage methods have been considered and studied, but for example, devices that use water as a heat storage medium to store solar thermal energy and store heat in the form of sensible heat are generally familiar. .

. However, when heat is stored in the form of sensible heat, even if the heat storage tank is made of a material with excellent insulation effects, a considerable amount of energy is released before it is used for heat dissipation, and the heat storage effect is not very good. It wasn't something. The same can be said of heat storage devices that utilize latent heat. By the way, a heat storage method using metal hydrides has been proposed as a heat storage method that does not have the above drawbacks (for example, Shuichiro Ono, Chemistry Area vol. 131, No. 1, P. 39-P. 47, 19
1977), but nothing has been realized yet, and since the main use of metal hydrides is for storage of water streams, there are virtually no examples of practical studies.

This method of using metal hydrides involves storing heat by utilizing the decomposition endothermic reaction of the metal hydride, and dissipating the heat by the hydrogenation reaction (exothermic reaction) of the metal.

According to this method, compared to the case of using water, which is a conventional sensible heat storage method, for example, in the case of magnesium hydride, the amount of heat storage is greater than about one needle volume, and it is fundamentally different from the conventional heat storage method. Unlike this method, energy is chemically converted into a substance and stored, so it can be stored semi-permanently without needing to be kept warm. However, as a result of actually examining such a heat storage hollyhock, we found that the higher the heat of reaction of the metal, the higher the temperature required for hydrogenation, and depending on the metal type, hydrogenation will not occur unless the metal type is heated to 50 to 10 psi. It turns out that this method simply cannot be used.

In order to solve the above-mentioned problems, the inventors of the present invention proposed a method for hydrogenating metals with large heat of reaction.
Hydrogenation is performed on metals with low hydrogenation temperatures (hydrogenation is possible at around room temperature), and the reaction heat generated during this hydrogenation reaction is used to preheat materials with high hydrogenation temperatures to raise the hydrogenation temperature level. We found a way to raise the temperature and eventually convert it to a hydride with a large heat of reaction. In general, metal hydrides with large heat of reaction, such as LiH, NaH, KH,
MgH2, Ca, and Mg2NiHX do not decompose unless the temperature is about 20°C or higher, and the reverse reaction, hydrogenation reaction, is difficult to occur.

Therefore, preheating is required to cause the hydrogenation reaction of such substances. Therefore, in order to hydrogenate a metal with a large heat of reaction, first, a metal that can be hydrogenated at room temperature and generates a considerable amount of heat of reaction is placed in a heat-generating part (i.e., the main heat-generating part) containing a metal hydride with a large heat of reaction. It was decided to incorporate it into the . As a result, in the first step, hydrogen from the energy storage section is sent to the preheating heat generation section, and in the second step, hydrogen is sent to the main heat generation section using this heat as preheat. Hydrogenation to metals with large heat of reaction is performed. Next, the structure of the heat storage tank of the present invention will be specifically explained using the drawings.

In FIG. 1, the overall diagram is divided into four parts: a, a heat exchanger section, b, a heat generation section, c, a heat exchanger section, and d, a hydrogen storage section.

Further, the heat generating section b consists of a main heat generating section wide and a preheating heat generating section Q, and the preheating heat generating section is disposed in the main heat generating section. Also, the hydrogen storage section of d is separate from d and d.
It consists of two hydrogen storage sections. First, in the endothermic process, the heat medium (water) collected by the heat exchanger a is sent to the heat generating part b filled with metal hydride.

At this time, the metal hydride in the main heat generating part and the preheating heat generating part performs an endothermic reaction, while misaki The decomposition (dehydrogenation) reaction shown in the figure below occurs, and the hydrogen generated from the main heat generation section is stored in the hydrogen storage section d, and the hydrogen generated from the preheating heat generation section is hydrogen. Stored in storage units.

On the other hand, in the process of extracting and utilizing the stored energy, that is, the heat dissipation process, the hydrogen stored in the hydrogen storage parts d and d2 is sent to the heat generation part b, and at this time,
An exothermic reaction takes place as follows: M+ ratio→M side.

The heat obtained from this exothermic reaction is passed through hot soot (eg air) and utilized by a C heat exchanger. The inner preheating heat generating section is filled with metal that can be hydrogenated at low temperatures (near room temperature), so this section is first made to generate heat by hydrogenation, and the main heat generating section around this preheating heat generating section is heated. The amount of heat necessary to raise the temperature of the metal filled in the tank to the starting temperature of the hydrogenation reaction is supplied. Once the hydrogenation reaction occurs, the metal in the main heat generating part maintains the high temperature due to its own reaction heat, so hydrogenation continues and efficient thermal energy can be extracted at high temperature. Examples of metal hydrogenation that can be used in the main heat generating part of this invention include LiH, NaH, KH,
Examples include Mg ratio, CaH2, Mg2NiHx, etc., and examples of metal hydrides that can be used in the heat generating part for preheating include MmN.
Examples include hydrides of i5 (Mm is a mixture of rare elements and is collectively called misch metal).

The optimum metal hydride for these metal hydrides is determined by the temperature of the heat source to be collected (e.g. waste heat, solar heat) and the temperature of the heat medium that heats the heat generating part. In cases where it is heated to
It is preferable to use a magnesium hydride in the main heat generating section and a MmNi5 hydride or a FeTi hydride in the preheating heat generating section. In this invention, each of the main heat generation section and the preliminary heat generation section may be filled with a mixture of a metal or alloy that can be hydrogenated or dehydrogenated, or a hydride thereof, and a metal or alloy that cannot be hydrogenated. It is possible.

"Not hydrogenated" means that the hydridable metal or alloy used in this invention is not hydrogenated under the reaction conditions for hydrogenation. Metals or alloys that do not hydrogenate can be used in powder or granular form.

Addition of a metal or alloy that does not hydrogenate significantly improves heat conduction, improves the thermal efficiency of hydrogenation, and furthermore allows hydrogenation to be performed more uniformly over the entire heat generating area.

Any metal or alloy that can be used for this purpose may be used as long as it does not hydrogenate, and examples thereof include C and Ag. The mixing weight ratio of the metal or alloy that can be hydrogenated or dehydrogenated or its hydride and the metal or alloy that cannot be hydrogenated is 1:1 to 1:
0.1 is preferred.

This idea of adding metals or alloys that do not participate in hydrogenation or dehydrogenation is also applied to the heat storage tank (i.e., a heat storage tank with one heat generating part) proposed by Shuichiro Ono. It's something you get.

In the present invention, a heat pipe can be used for the heat exchanger section that can collect heat from the heat source and radiate it into the heat storage tank and/or the heat exchanger section that can extract thermal energy from the heat storage tank to the outside of the oven.

Any material can be used as a heat pipe, but for example, heat pipes using copper, which has good thermal conductivity, as the tube material and water, Freon 12, ethyl chloride, acetone, methanol, ammonia, etc. as the working fluid, are also suitable. As the wick part, mesh cloth or fibers are preferably used. In addition, when using copper as the pipe as mentioned above, in order to prevent hydrogen arms from forming due to contact with hydrogen during desorption, and also to prevent corrosion by metal hydrides (for example, M&Ni and steel heat pipes are Direct contact may generate Mg2Cu alloy, and since this alloy also absorbs hydrogen, there is a risk that the copper on the copper heat pipe will be attacked by metal hydrides) Surfaces of silver, gold, chromium, etc. Preferably, a treated film is formed.

Specifically, for example, in FIG. 2, such a heat pipe is made of copper (Wailong: 10
side? ) can be used. By using a heat pipe, heat can be transferred over a much greater distance and thermal efficiency is improved.

Next, the procedure for using the basket heating tank of the present invention will be explained with reference to FIG.

When storing heat, first, heat exchanger 1 is used to collect heat from a heat source such as waste heat, solar heat, etc., and the heat is transported to heat exchanger 2 via a heat medium (for example, water).

Furthermore, this heat also causes a decomposition reaction of the metal hydride in the main heat generating section Q and the preheating heat generating section Q, and the hydrogen gas generated thereby passes through the valve 8 to the hydrogen corresponding to the preheating heat generating section. Storage of hydrogen is carried out in the storage section d [i.e. hydrogen storage container 6] and through the valve 10, the hydrogen compression pump 13 and the valve 11 into the hydrogen storage station 2 [hydrogen storage container 7] corresponding to the main heat generating section. . When the energy stored in the form of hydrogen is taken out in the form of heat, hydrogen is first sent from the energy storage section (hydrogen storage container) through the valve 9 to the preheating heat generation section, which is the opposite of heat storage. At this time, heat generation occurs due to hydrogenation of the metal in b2, and if pressurized hydrogen is added to the metal 15 from the hydrogen storage container 7, the hydrogen storage section is also preheated via the heat conductor container 17. 15 metal hydrogenation reactions are induced. Note that the reaction heat of the once induced reaction further promotes the hydrogenation of the metal 15, and the temperature of the heat generating part b rises rapidly. This heat is removed from the outside air by the heat insulating material 15, and the structure is such that a sudden drop in temperature does not occur. The generated heat increases the temperature of hot soot (for example, air, water, etc.) by the heat exchanger 3, and this hot soot is sent to the heat exchanger section 4 of C, where it is extracted and used as heat.

In this figure, the heat medium is circulated by a pump. The following examples are given to illustrate the invention.

Example 1 Mg2Ni (280Kcal
An apparatus as shown in FIG. 1 was assembled using Ni5 (34 Kcal/k9) as a substance that can be hydrogenated at room temperature.

3000 assuming a solar house (heat source: solar heat)
M&Ni as a heat storage material for a heat storage amount of about 0Kcal
I prepared about 100k9. In addition, Ni5 for this
I prepared 11k9, which is about 1'9 of the previous amount. The container corresponding to the hydrogen storage container 7 for this amount was a 4375〆, that is, about one fifth pressure cylinder, which was compressed to a pressure of 8k9/cm. The hydrogen storage container 6 was made of Ni511k9 and was designed to withstand a pressure of 10k9/ground. When this heat storage tank was tested for heat utilization and heat storage, it showed excellent thermal efficiency.

Design example The heat generating part shown in Fig. 1 is more concretely shown in Fig. 2.
The stainless steel pipes 20, 21, 22, and 23 are used as metal heat generating parts, and the water pipes from the heat exchanger part a in FIG. 1 [18 in FIG. A heat generating section corresponding to Q in FIG. 1 and a pipe 19 in FIG. 2 are built into the unit.

The flow of hydrogen and water is as shown in FIG.
Note that the 'pipe 19 is made of metal corresponding to 16 in FIG.
That is, in the embodiment, LaNi5 is built-in. The passage for air, which is a heat medium used for extracting heat, in FIG. 1 is assumed to perform heat exchange using gaps between pipes. Reference Example 1 As a model experiment, the relationship between hydrogenation time and hydrogenation amount was determined using hydrogenation temperature as a parameter for Mg2Ni alone.

The results are shown in FIG. As can be seen from Figure 3, M
Axial Ni is difficult to hydrogenate near room temperature, and is 50 to 80 oo
Hydrogenation proceeds smoothly by heating. As suggested by this model experiment, by preheating to a temperature of 50°C or higher, it is possible to smoothly hydrogenate metals that have a large reaction heat and are difficult to hydrogenate at room temperature. This is extremely important when designing a cage heat system (or a heat storage tank) that uses chemical compounds.

Example 2 Mg2Ni (28
An apparatus as shown in FIG. 1 was assembled using 0 Kcal'k9) and LaNi5 (3 cycles cal/k9) as a substance that can be hydrogenated at around room temperature.

M&Ni powder (100 mesh) 100k9 was prepared as a heat storage material for a heat storage amount of about 30,000Kcal, and C powder of about 10% of this was prepared as a heat conductive material for this (thermal conductivity of Cu, 332Kcal/at 20°C).
hr. Moo, lower than the hydrogenation temperature of M saddle Ni, M
Any material that does not alloy with g2Ni, has good thermal conductivity, and does not form hydrides under the hydrogenation conditions described above can be used.

For this purpose, WNi5 powder (100 mesh) was prepared in an amount of about 1/11k9 of the previous amount, and an additive Cu powder (100 mesh) was prepared in an amount of 1k9. The container equivalent to the hydrogen storage container 7 for this amount was about 5,000 containers, which was compressed to a pressure of 8k9/kg, that is, about one fifth pressure-resistant cylinder. The hydrogen storage container 6 contained LaNi 511k9 and was designed to withstand a pressure of 10k9/ground. When heat utilization and heat storage tests were conducted using this cage heat amount, the thermal efficiency was superior to that of the device of Example 1. Reference Example 2 As a model experiment, the relationship between hydrogenation time and hydrogenation amount of M bag Ni powder (100 mesh) was determined using a metal (additive) that does not hydrogenate as a parameter.

Ag powder (100 mesh) and Cu powder (100 mesh) were used as metals that do not undergo hydrogenation. Hydrogenation was carried out at a weight ratio of M&Ni and these metals of 1:0.1 and a hydrogenation temperature of 33 and 0. The results are shown in FIG.
From FIG. 4, it can be seen that when Ag or Cu is added, the hydrogenation time is 3 hours compared to 1.5 hours when Ag is added, compared to when no metal is added. Sleeve time, C
In the case of u, it is shorter at 2 hours.

That is, if we roughly estimate the thermal efficiency, when Ag is used as an additive, it is 1.7 times that of no additive, and when Cu is used as an additive, it is 1.7 times that of no additive. The results are better when additives are added, resulting in sound sealing.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a specific example of the heat storage tank according to the present invention, FIG. 2 is a perspective view showing a more specific design example of the inside of the heat generating section of FIG. 1, and FIG. This is a graph showing the relationship between hydrogenation time and hydrogenation amount using hydrogenation temperature as a parameter, and Figure 4 shows the relationship between hydrogenation time and hydrogenation amount when a metal that does not hydrogenate is added and when a metal that does not hydrogenate is added. It is a graph showing the relationship. a... Heat exchanger section, q... Main heat generating section, b2... Preheating heat generating section, c......
・Heat exchanger section, d,, d2...Hydrogen storage section, 1
, 2, 3, 4... Heat exchanger, 5... Air pump, 6, 7... Hydrogen storage container, 8, 9, 10, 11,
12...Valve, 13...Hydrogen compression pump, 14...Insulating material, 15...Metal or alloy with large hydrogenation reaction heat or hydride thereof, 1
6...Metal or alloy or its hydride that can be hydrogenated at room temperature, 17...Thermal conductor, 18,
18'... Water conduit pipe, 19... Preheating heat generating section, 20, 21, 22, 23... Stainless steel pipe. Figure 3 Groove / Figure 2 Maiko figure

Claims (1)

[Claims] 1. Hydrides of two metals or alloys that can be dehydrogenated on the high temperature side and low temperature side are dehydrogenated using the heat of a heat exchange medium that has been collected in advance, and the hydrogen produced by this dehydrogenation is is stored, and when it is desired to use the heat, the metal or alloy that can be hydrogenated at a low temperature produced by the dehydrogenation reaction is hydrogenated with the stored hydrogen to generate heat, and this heat is used to generate hydrogen by the dehydrogenation reaction. A heat storage method characterized by utilizing a larger heat of reaction by bringing a metal or alloy that can be hydrogenated at a high temperature to a hydrogenation temperature and hydrogenating it with the stored hydrogen. 2. The method according to claim 1, wherein the metal or alloy or its hydride that can be hydrogenated/dehydrogenated at low temperature is MmNi_5 or FeTi or its hydride. 3. The method according to claim 1 or 2, wherein the metal, alloy, or hydride thereof that can be hydrogenated/dehydrogenated at high temperatures is magnesium or a hydride thereof. 4
In the same tank, there is a preheating heat generating section filled with metals, alloys, or their hydrides that can be hydrogenated and dehydrogenated at low temperatures, and hydrogenation at high temperatures arranged around this preheating heat generating section.・A main heat generating section filled with a metal or alloy capable of dehydrogenation or its hydride, a heat exchanger section that can collect heat from a heat source and radiate it into the tank, and a heat exchanger that can extract thermal energy from the tank to the outside of the tank. A hydrogen storage unit that stores hydrogen generated from the main heat generation unit and the preheating heat generation unit, and a hydrogen gas introduction unit that connects the hydrogen storage unit and both heat generation units to take in and out hydrogen gas. A heat storage tank characterized by being equipped with an outlet pipe. 5. The heat storage tank according to claim 4, wherein the hydrogen storage section is separated into a hydrogen storage section for the main heat generation section and a hydrogen storage section for the preheating heat generation section. 6 The metal hydride filled in the heat generating part for preheating is Mm
The heat storage tank according to claim 4, wherein the metal hydride filled in the main heat generating section is a hydride of magnesium, which is a hydride of Ni_5. 7 The metal hydride filled in the heat generating part for preheating is Fe.
5. The heat storage tank according to claim 4, which is a hydride of Ti, and the metal hydride filled in the main heat generating section is a hydride of magnesium. 8. Claim 4, wherein each of the main heat generation section and the preheating heat generation section is filled with a mixture of a metal or alloy capable of hydrogenation and dehydrogenation, or a hydride thereof, and a metal or alloy that does not hydrogenate. The heat storage tank according to any one of Items to Item 7. 9. The heat storage tank according to claim 8, wherein the weight ratio of the metal or alloy that can be hydrogenated and dehydrogenated or its hydride to the metal or alloy that cannot be hydrogenated is 1:1 to 1:0.1. 10 Claims 4 to 9 in which a heat pipe is used as a heat exchanger section that can collect heat from a heat source and radiate it into a heat storage tank and/or a heat exchanger section that can extract thermal energy from the heat storage tank to the outside of the tank. The heat storage tank described in any of paragraphs.