JPS62119393A - Heat exchanger for metal hydride - Google Patents

Abstract

PURPOSE:To make it possible to improve heat exchanging capability as well as to present ease of manufacture with compactness in construction by providing longitudinally long, corrugated plate shaped heat transfer fins axially on the outer surface of a heat carrier tube the inner cross section of which is corrugated and maintaining always the same shape with respect to positions in the axial direction. CONSTITUTION:A heat carrier 3 is made to flow in a heat carrier tube 1, and in the gaps among heat transfer fins 2 a metal hydride 4 is filled so that a heat exchange occurs between the heat carrier 3 and the metal hydride 4. The hydrogen which is absorbed or discharged with an endothermic reaction or an exothermic reaction is led out to the outside or led in from the outside through a filter 5 through which hydrogen can pass but powders of metal hydrides can not pass. By this constitution with a heat carrier tube 1 at the central position, thermal stresses which develop during the exothermic reaction of a metal hydride 4 arranged round the outer circumference of the heat carrier tube 1 are dissipated towards outside, and thermal stress developed in the heat carrier tube 1 becomes thereby small, and because the internal cross-sectional shape of the heat carrier tube 1 is corrugated, the thermal stress applied onto the heat carrier tube 1 is absorbed to the inner wall with no fear that the tube 1 will be damaged by the stress, and the heat exchange with the heat carrier 3 is made efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a metal hydride heat exchanger suitable for storing and extracting heat by utilizing the reversible reaction of metal hydrides.

(b) Prior art Certain metals or alloys react reversibly with hydrogen, and attempts to use the heat of reaction generated at this time for heat storage, etc. are currently on hold, and various metal hydride utilization devices have been developed. Suggestions are being made.

However, what has been proposed so far is, for example,
As seen in Japanese Patent Laid-open No. 194701 and Japanese Unexamined Patent Publication No. 58-47989, all of them had a structure in which a hydrogen gas inlet/output conduit was arranged at the center and a heat exchanger was arranged outside. Therefore, if a shock is applied for some reason during an exothermic reaction accompanied by hydrogen absorption, causing an explosive reaction, there is a risk that the heat exchanger will be damaged by the large outward thermal stress.

Therefore, in order to eliminate such problems, the applicant first
We proposed a metal hydride container in which a heat exchanger is constructed by arranging a heat transfer pipe in the center to flow a heat medium, and providing flat heat transfer fins that radiate out from the heat transfer pipe in the axial direction ( (See the specification of Japanese Patent Application No. 33698/1983).

According to this, even if an exothermic reaction suddenly occurs, the thermal stress generated at that time is dissipated outward, thereby preventing damage to the heat exchanger.

In addition, the heat exchanger has a cylindrical structure with longitudinal flat heat transfer fins along the axial direction of the heat medium tube, so it can be easily manufactured by extrusion molding without seams that can cause heat transfer resistance. It also has the advantage of being manufacturable.

(c) Problems to be Solved by the Invention However, in the above heat exchanger, if the dimensions of the flat heat transfer fins are extended in the radial direction in order to increase the heat transfer area, There is a large difference in the distance from the heat transfer surface near the outer periphery, and in the metal hydride packed bed near the outer periphery where the distance from the heat transfer surface is large, heat exchange with the heating medium is faster than in the metal hydride packed bed near the center. Speed decreases. As a result, the reaction becomes non-uniform and the overall heat exchange capacity decreases. In addition, the size becomes large, making it impossible to construct a compact heat exchanger. On the other hand, in order to increase the heat transfer area while keeping the distance between the metal hydride layer near the outer periphery of the heat exchanger small and the fins compact, it is possible to increase the number of fins by extrusion, etc. There was a problem that the molding process was repeated.

(d) Means for Solving the Problems The object of the present invention is to provide a metal hydride heat exchanger that can be easily manufactured by integral molding, is compact, and has a large heat exchange capacity.

The external surface of the heat medium tube, which has a corrugated internal cross-sectional shape, is provided with longitudinally corrugated plate-shaped heat transfer fins along the axial direction, which are necessary for heat conduction with the metal hydride, and are always at the same axial position. The heat exchanger is configured to have the same shape.

(e) By placing the working heat transfer pipe in the center of the metal hydride,
Thermal stress applied to the heat medium tube during the exothermic reaction is reduced, and damage to the heat exchanger is prevented. By making the internal cross-sectional shape of the heat medium pipe corrugated, the rate of heat exchange with the heat medium is improved. In addition, by providing corrugated heat transfer fins on the external surface of the heat transfer pipe, the heat transfer area can be increased, and the distance between the metal hydride packed layer near the outer periphery of the heat exchanger and the heat transfer fins can be increased. can be kept small. Furthermore, since the entire heat exchanger has the same shape with respect to its axial position, it can be easily manufactured by extrusion molding.

(F) Embodiment FIG. 1 shows a metal hydride heat exchanger according to an embodiment of the present invention, in which (a) is a perspective view thereof, and (b) is a radial cross-sectional view thereof. In the heat exchanger of this embodiment, the inner wall surface of the heat medium pipe 1, which serves as a flow path for the heat medium, is formed into a corrugated shape parallel to the axial direction, and extends in the radial direction from the outer wall surface of the heat medium pipe 1. The eight heat transfer fins 2 are also formed in the shape of corrugated plates parallel to the axial direction.

By flowing the heat medium 3 into the heat medium pipe 1 of this heat exchanger and filling the gap between the heat transfer fins 2 with the metal hydride 4, heat is exchanged between the heat medium 3 and the metal hydride 4. will be carried out. Usually, the metal hydride 4 is surrounded by a filter 5 that allows hydrogen to pass through but does not allow the metal hydride powder to pass through and is housed in a pressure-resistant container, and the hydrogen absorbed and released by an endothermic reaction is passed through the filter 5 to the outside. It will be taken in and taken out.

In this way, by configuring the heat exchanger by arranging the heat medium pipe 1 in the center, the thermal stress generated during the exothermic reaction of the metal hydride 4 arranged around the outer periphery of the heat medium pipe 1 is directed outward. Therefore, the thermal stress applied to the heat transfer pipe 1 becomes smaller. Moreover, at this time, the internal cross-sectional shape of the heat medium tube 1 was formed into a wave shape.

Thermal stress applied to the heat medium tube 1 is absorbed by its corrugated inner wall, and there is no possibility that the heat medium tube 1 will be destroyed by the thermal stress. Moreover, heat exchange with the heat medium 3 can also be performed efficiently.

On the other hand, since corrugated heat transfer fins 2 are provided on the outside of the heat medium pipe 1, the heat transfer area can be increased without increasing the outer diameter of the heat exchanger. The distance between the metal hydride packed layer near the outer periphery of the vessel and the heat transfer fins can be shortened. As a result, the heat exchange capacity with the metal hydride 4 can be increased, and in the case of the same heat exchange capacity as before.

The outer diameter dimension can be shortened, making it possible to make it more compact.

Furthermore, since the entire heat exchanger has the same shape with respect to its axial position, it can be easily manufactured by extrusion molding.

Note that the radial cross-sectional view of the heat exchanger is not limited to the shape shown in Figure 1(b), but may have a shape that is constant in the axial direction, such as the uneven wave shape shown in Figure 2. Any shape can be adopted as long as it is formed.

Further, the number of heat transfer fins 2 is not limited to eight, and any number can be adopted, but increasing the number too much will increase the sensible heat of the fins themselves, lowering the efficiency, and Integral molding is also undesirable because it is difficult to process.

FIG. 3 shows another embodiment of the present invention. In FIG. 0, ( (a) is an external view of the metal hydride reaction vessel, (b) is a radial cross-sectional view, and (c) is an axial cross-sectional view, and the same reference numerals as in FIG. 1 indicate the same parts.

As shown in FIG. 1, the metal hydride reaction vessel of this embodiment has a filter cylinder 5 and a heat medium pipe 1. A heat exchanger consisting of heat transfer fins 2 is housed under pressure, a metal hydride 4 is filled between the heat transfer fins 2, and the surrounding area is covered with a heat insulating material 6 such as Kao Wool (trade name), and the heat exchanger is placed in a pressure vessel 7. It is made up of storage. The pressure vessel 7 is equipped with a hydrogen introduction exhaust lower a with a hydrogen filter 8 at the negative joint, and a flange 7b at the other end.
The inside is sealed.

With the above configuration, the metal hydride 4 inside one reaction vessel passes through the filter 5, the hydrogen filter 8, and the heat insulating material 6,
It can react with hydrogen introduced and exhausted from the hydrogen introduction/exhaust lower a connected to a hydrogen storage device (not shown).

During the heat dissipation process in a heat storage device or the like, the metal hydride 4 undergoes a hydrogenation reaction with hydrogen introduced from the hydrogen introduction exhaust lower a.

The reaction heat generated at this time is quickly transferred to the heat medium flowing inside the heat medium pipe 1, efficiently taken out to the outside, and supplied to heat loads such as space heating and hot water supply. Also.

In the heat storage process, heat is transferred to the metal hydride reaction vessel from a heat medium heated by an external heat source such as a solar collector or factory waste heat, and the metal hydride is transferred to the metal hydride reaction vessel through the metal hydride heat exchanger according to the present invention. is rapidly transferred to dehydrogenate the metal hydride 4. The hydrogen gas generated at this time is exhausted from the hydrogen introduction exhaust lower a.

FIG. 4 shows a configuration diagram of a metal hydride reaction vessel according to still another embodiment of the present invention, in which (a) is an axial cross-sectional view, and (b) is a radial cross-sectional view. . In the figure, the same reference numerals as in FIG. 3 indicate the same or corresponding parts, and the main differences from FIG. 3 are filter 5. The fact that a filter cylinder 9 that also serves as a heat insulating material is provided instead of the heat insulating material 6, the radial cross section of the heat medium pipe 1 and the heat transfer tube 2 are formed into an uneven wave shape, and the thickness of the heat medium pipe 1 is The point is that a hollow portion 10 is provided in the thick portion.

When the reaction vessel is constructed in this manner, the same effects as in the embodiment shown in FIG. 3 can be obtained.

Thermal stress directed inward during the exothermic reaction is also absorbed by the hollow portion 10 formed in the thick portion of the heat transfer pipe 1, and the influence of the thermal stress can be further alleviated.

(g) Effects of the Invention As described above, according to the present invention, a metal hydride reaction vessel which is compact and has excellent heat exchange ability can be obtained. This will increase the thermal efficiency of heat storage devices or heat pumps that utilize the reversible reaction heat of metal hydrides, promote the effective use of solar heat or factory exhaust heat, and contribute to the miniaturization of these devices. become able to.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a metal hydride heat exchanger according to an embodiment of the present invention, (a) is a perspective view thereof, (b) is a radial cross-sectional view thereof, and FIG. FIG. 3 is a radial cross-sectional view of a metal hydride heat exchanger according to a second embodiment, and FIG. 3 is a configuration diagram of a metal hydride reaction vessel according to a third embodiment of the present invention.
(a) is its external view, (b) is its radial cross-sectional view, (
c) is an axial sectional view thereof. FIG. 4 is a block diagram of a metal hydride reaction vessel according to a fourth embodiment of the present invention, in which (a) is an axial sectional view, and (b) is a radial sectional view. 1... Heat medium pipe, 2... Heat transfer fin, 3... Heat medium, 4
...Metal hydride. Agent Patent Attorney Crest 1) Makoto. Figure 1 (b) Figure 2 Figure 3

Claims (1)

[Claims] A heat transfer pipe through which a heat transfer medium flows is placed along the central axis, and a plurality of vertically elongated heat transfer fins that hold metal hydride are provided along the axial direction of the external surface of the heat transfer pipe to form a cylindrical shape as a whole. In addition, the radial cross-sectional shape of the entire cylindrical shape is characterized in that the inner wall of the heat medium tube is corrugated, the heat transfer fins are corrugated, and the shape is always the same along the axial direction. Heat exchanger for metal hydrides.