JPS63259300A - Heat exchanger unit for hydrogen storage alloy - Google Patents

Abstract

PURPOSE:To raise the heat exchanger effectiveness, by setting plate-shaped filters for hydrogen permeation, on window holes of an inner cylinder which contains hydrogen-storing alloy and a heat exchanger, and setting a pipe-shaped filter for hydrogen permeation, in the hydrogen-storing alloy. CONSTITUTION:An inner cylinder 2 which contains hydrogen-storing alloy 10 and a heat exchanger 9, is set in an outer cylinder 1. Plate-shaped filters 7 for hydrogen permeation are set on window holes 12 of the inner cylinder 2, and a pipe-shaped filter 6 for hydrogen permeation is set in the hydrogen-storing alloy 10. With this formation, the heat exchanger effectiveness can be raised by rise of reacting rate, brought by rise of coefficient of thermal conductivity between the hydrogen-storing alloy and the heat exchanger, and speedy feed and keeping of hydrogen gas to the hydrogen-storing alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat exchanger unit, and particularly to a heat exchanger unit for hydrogen storage alloys used in hydrogen storage, heat storage, heat pumps, etc. using metal hydrides.

(Prior art) La-Ni alloy, which is generally known as a hydrogen storage alloy, M
m-Ni alloy (Mm is Mitsushi Metal), Ryu-Ni alloy, Fe-Ti alloy, etc. react reversibly with hydrogen and form CMH.
)+Q: (M) +H.

(M is alloy, Q is reaction heat) There is a relationship.

Hydrogen contained in the hydrogen storage alloy has a hydrogen density approximately 1000 times that of hydrogen gas under standard conditions, and has excellent hydrogen storage ability. Furthermore, hydrogen storage and transportation systems using hydrogen storage alloys are being considered because they are superior to liquid hydrogen and solid hydrogen in terms of safety and economy.

In addition, as shown in the above equation, by utilizing the fact that a hydrogen storage alloy absorbs and releases reaction heat when it reversibly reacts with hydrogen, hydrogen storage alloys can be used as a heat storage body for solar heat, wind power, industrial plants, etc. Thermal storage systems are being developed that store waste heat, etc., and extract and use the heat as needed.

Furthermore, a heat pump system is also being developed that uses exhaust heat or the like to repeatedly absorb and release hydrogen at certain intervals, and utilizes the heat absorbed or exothermic reaction generated at that time.

In any of the above systems, the most important thing is
It is a rapid reaction between hydrogen and a hydrogen storage alloy, and the performance of the system is determined by the reaction rate and amount of reaction. Hydrogen storage alloys generally produce 3 by reacting with hydrogen.
It is accompanied by a volumetric expansion of about 0%, which results in pulverization. The thermal conductivity of the finely powdered hydrogen storage alloy is only about 1/300 of that of IW#nK and copper, and the powder particle size is as small as several microns to several tens of microns. heat conduction and hydrogen permeation are the biggest obstacles to the purpose of accelerating the reaction of hydrogen storage alloys.

In JP-A-56-114802, a block of a thermally conductive porous material is filled with a finely divided metal hydride, and the block is covered with a filter having holes smaller than the particle size of the metal hydride to absorb hydrogen. The unit is disclosed. Japanese Unexamined Patent Publication No. 1983
Publication No. 23796 has a pressure vessel that holds hydrogen gas and a heat exchange section inside the pressure vessel, and the heat exchange section consists of a container made of a material with appropriate air permeability and strength, and an inner surface of the wall thereof. A heat insulating material having appropriate heat retention, air permeability, and bulk elasticity, a heat exchange tube disposed in a space surrounded by the heat insulating material, and hydrogen storage alloy particles filled in the space. The pressure vessel is connected to the hydrogen gas piping outside the heat exchanger, and both ends of the heat exchange tube are connected to the heat exchange fluid piping outside the heat exchanger via tubes installed inside the pressure vessel.
A heat exchanger using an elementary storage alloy is disclosed. In Japanese Utility Model Publication No. 62-478, a plurality of thin-walled tube vessels for hydrogen storage are arranged in parallel, can withstand high operating pressure, and the tube vessels, heat exchange member, and intervening member are tightly bonded with a binding band. We are proposing a relatively small and lightweight hydrogen storage container that is bundled together. In addition, in Japanese Utility Model Publication No. 62-479, concave receiving plates on which a hydrogen storage alloy is placed inside the case are arranged in multiple stages at predetermined intervals in the upper and lower directions. A hydrogen storage container is proposed in which the case is provided with a hydrogen supply port and a hydrogen discharge port, and a heat medium passage pipe is passed through a concave receiving plate.

Generally, a heat exchanger unit using a hydrogen storage alloy is composed of a hydrogen gas storage section, a hydrogen storage alloy filling section, a heat insulation section, a heat exchanger section, and a part of a filter.

(Problems to be Solved by the Invention) Conventionally, in such a heat exchanger unit, a hydrogen storage alloy with a volume of 30% of the volume of the hydrogen storage alloy is used as a hydrogen gas holding portion in anticipation of volumetric expansion when the hydrogen storage alloy stores hydrogen. % or more, but if the voids were provided in anticipation of expansion of the hydrogen storage alloy, the contact between the hydrogen storage alloy powders would be weak, resulting in a decrease in the thermal conductivity of the hydrogen storage alloy. Furthermore, the contact between the heat exchanger and the hydrogen storage alloy is weak, and the heat exchange rate is inevitably reduced here as well. On the other hand, if the gap in the hydrogen gas holding part is made smaller than the amount of expansion of the hydrogen storage alloy and the hydrogen storage alloy is held down by the hydrogen gas holding container, hydrogen gas pressure and hydrogen storage alloy expansion pressure will be applied to the container. Therefore, the container must be designed with an excessively high pressure-resistant structure, which is undesirable as it increases the weight. Furthermore, when pressure is applied to the hydrogen storage alloy to form a densely packed bed, the flow of hydrogen decreases, and even if the heat conduction of the hydrogen storage alloy improves, it is difficult for hydrogen to be supplied to the hydrogen storage alloy.

The purpose of the present invention is to accelerate the reaction rate by improving the thermal conductivity between the hydrogen storage alloy and the heat exchanger, which is a problem in heat exchanger units using hydrogen storage alloys, and to quickly transfer hydrogen gas to the hydrogen storage alloy. It is an object of the present invention to provide a heat exchanger unit for a hydrogen storage alloy that can improve the heat exchange efficiency by securing supply, can easily be made larger, and can reduce manufacturing costs with a simple structure.

(Means for Solving the Problems) The present invention comprises a hydrogen gas pressure holding outer cylinder having a hydrogen gas pipe joint, and a heat exchange inner cylinder housing a hydrogen storage alloy and a heat exchanger therein. The outer cylinder and the inner cylinder are separated by a space that serves as heat insulation and a hydrogen flow path, and a window hole provided in a part of the inner cylinder has a plate shape, and a pipe is inside the hydrogen storage alloy powder layer. A heat exchanger unit for a hydrogen storage alloy is characterized in that each hydrogen permeation filter is provided in the hydrogen storage alloy, and in the heat exchanger unit, the hydrogen storage alloy is provided with dendritic copper or iron or flake copper, The above problem is solved by mixing 5 to 30% of metal powder of aluminum or iron with a particle size of 0.04 to 4 mm.

Next, the present invention will be explained in detail based on the drawings.

FIG. 1 shows a longitudinal cross-sectional view of a heat exchanger unit for a hydrogen storage alloy according to the present invention, which includes an outer cylinder 1 that holds hydrogen gas pressure, and a hydrogen storage alloy (hereinafter simply referred to as "alloy") in the form of a powder layer inside the outer cylinder 1. 10 and an inner cylinder 2 that accommodates a heat exchanger 9, FIG. 2 shows a longitudinal cross-sectional view of the inner cylinder 2, and FIG. 3 is a cross-sectional view taken along the line AA' in FIG. .

The outer cylinder 1 and the inner cylinder 2 are airtightly connected by welding. This may also be done by other joining methods such as a flange structure. The outer cylinder 1 and the inner cylinder 2 are separated by a space 5 that serves as heat insulation and a hydrogen flow path.

A breathable material such as Kao wool or glass wool may be filled as a heat insulating material. A hydrogen gas pipe joint 3 is attached to the outer cylinder 1. The inner cylinder 2 includes a heat medium inlet 4, an outlet 4', a heat exchanger 9, an alloy 10, an alloy filling lid 8, and a plate-shaped plate fixed to a window hole 12 provided in a part of the inner cylinder 2. It is composed of a hydrogen permeation filter 7 and a pipe-shaped hydrogen permeation filter 6 placed in a powder layered alloy 10. A heat insulating material may be attached to the inner wall of the inner cylinder 2. The material for the outer tube 1, the inner tube 2, and the alloy filling lid 8 is preferably hydrogen-resistant steel, stainless steel, or the like having appropriate strength.

Further, as the material for the pipe-shaped filter 6 and the plate-shaped filter 7, a sintered body of metal powder such as copper or stainless steel is suitable.

Further, the material of the heat exchanger 9 is preferably a copper tube with high thermal conductivity, a stainless steel tube with high corrosion resistance, or the like.

The heat exchanger 9 is connected to the heat medium inlet 4 and further connected to the inner cylinder 2.
It consists of a plurality of tubes that make a U-turn inside and are connected to a heat medium outlet 4'.

When filling the inner cylinder 2 with alloy 10, the alloy 10 is filled in such a way that excessive internal pressure is not generated when the alloy 10 absorbs hydrogen and expands, and there is no excess space left above the alloy 10. Fix the filling lid 8 with screws.

After that, insert the inner cylinder 2 into the outer cylinder 1, and connect the inner cylinder 2 and the outer cylinder 1.
The assembly of this device is completed by welding and fixing the connecting portion 11 of the device while maintaining airtightness.

Next, the operation of this device will be explained.

When hydrogen is stored in the alloy 10 in this device, hydrogen gas is supplied from the hydrogen gas pipe fitting 3 under predetermined temperature and hydrogen pressure conditions, so that the hydrogen gas passes through the space 5 and passes through the outer cylinder 1. enters the alloy 10 from the plate-shaped filter 7 and the pipe-shaped filter 6,
occluded. At this time, heat of reaction with hydrogen is generated from the alloy 10 and transferred to the heat medium via the heat exchanger 9. Next, when hydrogen is released from the alloy 10, a heat medium at a predetermined temperature is supplied from the heat medium inlet 4. At this time,
The temperature of the heat medium is transmitted to the alloy 10 via the heat exchanger 9, which releases hydrogen at a predetermined pressure and absorbs heat at the same time. Alloy 10
The hydrogen released from the hydrogen gas pipe passes through the plate-shaped filter 7 and the pipe-shaped filter 6, passes through the space 5, and is released from the hydrogen gas pipe joint 3. In this device, hydrogen can be quickly supplied to the alloy 10 by uniformly applying hydrogen pressure to the inner cylinder 2 through the space 5. At this time, the pressure inside and outside of the inner cylinder 2 quickly becomes the same, so the inner cylinder does not need to have a hydrogen gas pressure-resistant structure. Furthermore, with this structure, it is possible to minimize the use of expensive filters for hydrogen supply, which greatly contributes to cost reduction. Moreover, since the alloy 10 is surrounded by the inner cylinder 2, it is slightly pressed down by the expansion of the alloy when the alloy 10 absorbs hydrogen. For this reason, alloy 1
0 not only makes close contact with the heat exchanger 9 and improves the heat exchange rate, but also reduces the porosity of the alloy 10 and improves the thermal conductivity of the alloy 10 itself. Therefore, the reaction between alloy 10 and hydrogen is promoted and practical thermal efficiency is improved. At this time, inner cylinder 2
is subjected to some pressure as alloy 10 tries to expand,
There is no effect on the outer cylinder 1, which is a hydrogen gas container. Further, since the space 5 has a heat insulating effect, the reaction heat of the alloy 10 is prevented from leaking to the outside, and thermal efficiency is improved.

If it becomes necessary to increase the size of the system and increase the size of this device, increasing the size in the longitudinal direction will have no effect at all, but if increasing the size in the diametrical direction, hydrogen permeation will deteriorate due to the resistance of the alloy 10 itself. By increasing the number of pipe-shaped filters 6 according to the diameter of the alloy 10, hydrogen can be quickly supplied to the alloy 10 even if the device is made large in size, as in the case of a small device.

Conventionally, methods have been considered to improve the thermal conductivity of Alloy 10 by mixing powder of a metal with good thermal conductivity such as copper or aluminum into Alloy 10, and then compression molding it using CIP (cold isostatic pressing) or the like. However, the process is complicated and costs are high. On the other hand, in this device, only 5 to 30% of metal powder consisting of dendritic copper or iron, or flake-shaped copper, aluminum or iron with a particle size of 0.04 to 4 mm is mixed into Alloy 10. After that, it was found that the expansion force of Alloy 10 when absorbing hydrogen causes natural compression molding, and that the dendritic copper or iron or the flaky copper, aluminum, or iron come into contact with each other. .

Therefore, the thermal conductivity of Alloy 10 could be significantly improved due to the synergistic effect of the close packing of Alloy 10 and the mixed metal powder.

The reason why the metal powder is made into a dendritic or flake shape is to provide a powder having a large specific surface area. For example, in the case of a spherical or granular shape, a large amount must be mixed in order to improve the heat conductivity of the alloy 10, which results in wasteful sensible heat loss and reduces thermal efficiency. The reason why the particle size of the metal powder is set to 0.04 to 4 mm is that if it is less than 0.04 m, there will be too many contact points or surfaces between the mixed metal particles, resulting in a decrease in heat conductivity. If it is too small, it will be difficult to handle in terms of powder mixing, etc., while if it exceeds 4 cranes, the gaps between the mixed metal powders will be too large and the heat conductivity will not improve as expected.

In addition, the reason why the metal powder mixing rate was set at 5 to 30% was 5.
If it is less than 30%, the contact between the metal powders cannot be maintained and the heat transfer property cannot be improved. On the other hand, if it exceeds 30%, there will be excess metal powder that does not contribute to the improvement of the heat transfer property, resulting in sensible heat loss, that is, thermal efficiency. This results in a decrease in

Example 1: The results of investigating the reaction rate using the heat exchanger unit for hydrogen storage alloy of the present invention are shown.

(Conditions) Powder layered hydrogen storage alloy: Supply amount of Ti-Fe hydrogen storage alloy 10KgH2:
60 ONl The reaction rate when carried out under the above conditions was 8 minutes.

As a comparative example, the reaction rate was 10 minutes when the reaction was carried out under the same conditions as above using a heat exchanger unit without the pipe-shaped hydrogen permeation filter 6. It can be seen from this that the reaction rate of the unit of the present invention is 2 minutes faster.

Example 2: When Example 1 was carried out by mixing 3.3 kg of dendritic copper powder with 10 kg of the Ti-Fe hydrogen storage alloy, the reaction rate was 5 minutes. It can be seen from this that the reaction rate is 3 minutes faster than in the case of using only the Ti-Fe hydrogen storage alloy.

Example 3: 10 kg of T1-Fe hydrogen storage alloy in Example 1
When 1.8 kg of flaky aluminum powder was mixed into the mixture, the reaction rate was 5 minutes. This shows that the reaction rate is 3
I know it's faster.

(Effects of the Invention) According to the heat exchanger unit for a hydrogen storage alloy of the present invention, the reaction rate is accelerated by improving the thermal conductivity between the powder layered hydrogen storage alloy and the heat exchanger, and the hydrogen gas is transferred to the hydrogen storage alloy. By securing prompt supply, the heat exchange rate can be improved,
In addition, it can be easily made larger and has a simple structure, so manufacturing costs can be reduced, which is extremely effective.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of the heat exchanger unit for hydrogen storage alloy according to the present invention, Fig. 2 is a longitudinal sectional view of the inner cylinder of Fig. 1, and Fig. 3 is a sectional view taken along line AA' in Fig. 1. be. 1... Outer cylinder for holding hydrogen gas pressure, 2... Inner cylinder, 3...
...Hydrogen gas pipe joint, 4...Heat medium inlet, 4'...
- Heat medium outlet, 5... Space, 6... Pipe-shaped hydrogen permeation filter, 7... Plate-shaped hydrogen permeation filter, 8... Hydrogen storage alloy filling lid, 9...・
Heat exchanger, 10... Powder layered hydrogen storage alloy, 11... Connection portion between inner cylinder and outer cylinder, 12... Window hole. Patent applicant Nippon Yakin Kogyo Co., Ltd. Agent Patent attorney Jun Ogawa Sando Patent attorney Mura 1) Politics Figure 1 Figure 2 Figure 9 I

Claims (1)

[Claims] 1. Consisting of an outer cylinder for maintaining hydrogen gas pressure having a hydrogen gas pipe joint, and an inner cylinder for heat exchange that houses a hydrogen storage alloy and a heat exchanger inside the outer cylinder, the outer cylinder and the inner cylinder It is separated from the cylinder by a space that serves as heat insulation and a hydrogen flow path, and a plate-shaped hydrogen permeation filter is installed in the window hole provided in a part of the inner cylinder, and a pipe-shaped filter is installed in the powder layered hydrogen storage alloy. A heat exchanger unit for hydrogen storage alloys, characterized in that each unit is equipped with a filter for hydrogen permeation. 2. Claim 1, wherein in the heat exchanger unit, 5 to 30% of copper or iron metal powder having a dendritic particle size of 0.04 to 4 mm is mixed into the hydrogen storage alloy. Heat exchanger unit as described. 3. In the heat exchanger unit, 5 to 30% of flaky metal powder of copper, aluminum or iron having a particle size of 0.04 to 4 mm is mixed into the hydrogen storage alloy. The heat exchanger unit according to item 1.