HEAT EXCHANGER

Abstract

Provided is a heat exchanger in which heat exchange between a low-temperature cooling medium and brine and heat exchange between brine and hydrogen gas can be efficiently performed and downsizing of cooling facilities or reduction in facility cost can be attained. The heat exchanger comprises: a vacuum insulated container 12 which is filled with brine, a lid 13 closing an upper portion opening of the container, a rotation axis 14 arranged in the axis direction of the container, a propeller 15 provided on the rotation axis, a helical hydrogen gas cooling tube 16, 17 provided in a vertically two-stage structure around the rotation axis and the propeller, and a cooling medium tube 18 for cooling brine which is arranged around the hydrogen gas cooling tubes.

Description

TECHNICAL FIELD

The present invention relates to a heat exchanger, and more particularly to a heat exchanger which is suitable for a heat exchanger for cooling hydrogen gas which is set up in a facility filling a fuel tank of a hydrogen automobile or the like with a hydrogen gas.

BACKGROUND ART

Hydrogen gas which is used as a fuel for a hydrogen automobile such as a fuel-cell automobile has the property that the temperature thereof rises due to the Joule-Thompson effect when it is adiabatically expanded at a portion such as a variety of valves or flowmeters provided along a pathway through which hydrogen gas flows. The temperature of hydrogen gas therefore rises due to the Joule-Thompson effect when hydrogen gas passes at a valve or the like provided along a pathway from a source of hydrogen gas supply through which a hydrogen automobile is filled with hydrogen gas. At the same time, the temperature of hydrogen gas rises also due to heat of compression when hydrogen gas is compressed at a high pressure and a fuel tank of the hydrogen automobile is filled therewith.

There arises such a problem that the temperature of a fuel tank exceeds the upper limit temperature thereof 85° C. when the temperature of hydrogen gas rises or a problem that the pressure of the tank decreases as the tank is cooled after being filled with hydrogen gas. A variety of apparatuses or methods are therefore proposed in which a hydrogen automobile is filled with hydrogen while cooling hydrogen gas, by arranging cooling facilities along a pathway through which hydrogen gas flows, in the cooling facilities.

As the cooling facilities for cooling hydrogen gas, proposed are those in which brine is cooled by exchanging heat with a low-temperature cooling medium of a refrigerator to be stored in a storage tank and then, hydrogen gas is cooled with the low-temperature brine stored in the storage tank (see, for example, Patent Document 1) and those in which hydrogen gas is cooled by exchanging heat between a liquefied gas such as liquefied nitrogen and hydrogen gas (see, for example, Patent Document 2).

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: JP 2008-164177 A

Patent Document 2: JP 2008-267496 A

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

However, since the cooling facilities according to Patent Document 1 need a heat exchanger which exchanges heat between a low-temperature cooling medium in a refrigeration cycle and brine, a heat exchanger which exchanges heat between the brine and hydrogen gas, a brine storage tank, a piping and a pump for circulating brine, or the like, the facilities become complex and the footprint thereof is large, which makes the facility cost high. While the cooling facilities according to Patent Document 2 need only one heat exchanger and downsizing or simplification of the facilities is possible, since a liquefied gas which is consumed by exchanging heat with hydrogen gas needs to be constantly supplied, the running cost is considerably high, which is problematic.

Accordingly, an object of the present invention is to provide a heat exchanger in which heat exchange between a low-temperature cooling medium and brine and heat exchange between brine and hydrogen gas can be efficiently performed and downsizing of cooling facilities or reduction in facility cost can be attained.

Means for Solving the Problems

In order to attain the above-mentioned object, a heat exchanger which cools hydrogen gas with brine cooled by a low-temperature cooling medium according to the present invention is characterized by comprising:

a vacuum insulated container with which brine is filled;

a lid which closes the upper portion opening of the container;

a rotation axis arranged in the axis direction of the container;

a propeller provided along the rotation axis;

a helical hydrogen gas cooling tube arranged around the rotation axis and the propeller; and

a cooling medium tube for cooling brine arranged around the hydrogen gas cooling tube.

It is preferable in the above-mentioned heat exchanger; that the hydrogen gas cooling tube is provided with a plurality of hydrogen gas cooling tubes having a vertically multistage structure; that the upper end and the lower end of the cooling medium tube are communicatively connected to an annular upper portion manifold and an annular lower portion manifold, respectively, and a cooling medium is circulated in the cooling medium tube from the lower end to the upper end direction; that a gas-phase portion between the inner surface of the lid and the liquid surface of brine in the container is supplied with a dry gas; that a bottom portion of the container is provided with a drain for discharging brine with which the container is filled; that the container has a vertically long bottomed cylindrical shape and a lower portion of the container is supported with three or more support legs, and the container can be stood by itself with its axis vertical; and that the low-temperature cooling medium is a low-temperature cooling medium for refrigerators using a refrigeration cycle.

Further, a heat exchanger which cools hydrogen gas by brine which is cooled by a low-temperature cooling medium is characterized by comprising a vacuum insulated double walled vertically long bottomed cylindrical container which is filled with brine, a lid closing an upper portion opening of the container, a rotation axis which penetrates the center of the lid to be inserted in the container in the axis direction, a propeller provided on the rotation axis, a helical hydrogen gas cooling tube provided around the rotation axis and the propeller, and a plurality of cooling medium tubes for cooling brine which are arranged around the hydrogen gas cooling tube, whose upper ends and lower ends are communicatively connected to an annular upper portion manifold and an annular lower portion manifold, respectively, and through which a cooling medium supplied from a cooling medium inlet pipe communicating the lower portion manifold is discharged from a cooling medium outlet pipe communicating the upper portion manifold, wherein the rotation axis, the hydrogen gas cooling tube, the plurality of cooling medium tubes for cooling brine and the container are concentrically arranged centering on the rotation axis in a planar view in the order from inside mentioned below: the propeller, the hydrogen gas cooling tube, the plurality of cooling medium tubes for cooling brine and the container. It is preferable that the low-temperature cooling medium is a low-temperature cooling medium for refrigerators using a refrigeration cycle.

Effects of the Invention

According to the present invention, heat exchange which cools brine by a low-temperature cooling medium in a low-temperature cycle and heat exchange which cools hydrogen gas by the cooled brine can be performed in one container, and a storage tank for brine or a piping and a pump for circulating brine can be omitted, whereby downsizing of cooling facilities and reduction in facility cost can be attained. Since a low-temperature cooling medium for refrigerators is employed as a cold source, the running cost of the present invention can be reduced compared with those employing a liquefied gas as the cold source.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional front view showing one embodiment of a heat exchanger of the present invention.

FIG. 2 is a plan view of a heat exchanger in FIG. 1.

FIG. 3 is a III-III cross-sectional view of FIG. 1.

MODE FOR CARRYING OUT THE INVENTION

A heat exchanger 11 according to the embodiment comprises: a vacuum insulated double walled vertically long bottomed cylindrical container 12 which is filled with brine, a disk-shaped lid 13 closing an upper portion opening of the container 12, a rotation axis 14 which penetrates the center of the lid 13 to be arranged in the container 12 in the axis direction, a plurality of axial-flow propellers 15 provided on the rotation axis 14 in the vertical direction, a helical first hydrogen gas cooling tube 16 and a second hydrogen gas cooling tube 17 provided in a vertically two-stage structure around the rotation axis 14 and the propeller 15, and a plurality of cooling medium tubes 18 for cooling brine which are arranged around the first hydrogen gas cooling tube 16 and the second hydrogen gas cooling tube 17 in the axis direction.

The upper end and the lower end of each of the plurality of cooling medium tubes 18 for cooling brine are communicatively connected to an annular upper portion manifold 19 provided on the upper position of the first hydrogen gas cooling tube 16 and an annular lower portion manifold 20 provided on the lower position of the second hydrogen gas cooling tube 17, respectively. The cooling medium tube 18 for cooling brine corresponds to an evaporator in a refrigeration cycle, and cools brine around the cooling medium tube 18 by cold generated when a depressurized liquid cooling medium evaporates.

The container 12 is provided with three or more support legs 21 at a container lower portion and is formed such that the container can be stood by itself with its axis vertical. The bottom of the container 12 is provided with a drain 22 for discharging brine filling the container 12 at the time of maintenance or the like.

The lid 13 is detachably fixed on a flange 12a provided on the outer periphery of an upper portion of the container 12 by fasteners 23 composed of a multiple of bolts and nuts. On the center of the outer surface of the lid 13, a speed reducer 25 with a covering is provided in which the rotation speed of a drive shaft 24 which is rotatably driven by an air motor, not illustrated, is reduced to be transmitted to the rotation axis 14. The propeller 15 is rotated via the drive shaft 24, the speed reducer 25 and the rotation axis 14 by operating the air motor. The brine in the container 12 is elevated along the inner circumference sides of the first hydrogen gas cooling tube 16 and the second hydrogen gas cooling tube 17 by the rotation of the propeller and descended from the upper side of the first hydrogen gas cooling tube 16 along the outside of the cooling medium tube 18 and circulated from the lower side of the second hydrogen gas cooling tube 17 to the inner side of the second hydrogen gas cooling tube 17.

The lid 13 is provided with a first hydrogen gas inlet pipe 16a and a second hydrogen gas inlet pipe 17a which supply hydrogen gas from a source of hydrogen gas supply to the first hydrogen gas cooling tube 16 and the second hydrogen gas cooling tube 17, respectively, and a first hydrogen gas outlet pipe 16b and a second hydrogen gas outlet pipe 17b which outlet hydrogen gas cooled by the first hydrogen gas cooling tube 16 and the second hydrogen gas cooling tube 17 and transmit to a destination to be used, for example, a fuel tank of an automobile. The hydrogen gas cooling tubes 16,17 are connected with the first hydrogen gas outlet pipe 16b and the second hydrogen gas outlet pipe 17b, respectively, in a bonding structure which does not need a joint by butt welding.

The first hydrogen gas inlet pipe 16a is provided along the outer side of the first hydrogen gas cooling tube 16 in the axis direction and communicated to the lower end of the first hydrogen gas cooling tube 16; the first hydrogen gas outlet pipe 16b is communicated to the upper end of the first hydrogen gas cooling tube 16. The second hydrogen gas inlet pipe 17a is provided along the outer sides of the first hydrogen gas cooling tube 16 and the second hydrogen gas cooling tube 17 in the axis direction and communicated to the lower end of the second hydrogen gas cooling tube 17. The second hydrogen gas outlet pipe 17b is communicated to the upper end of the second hydrogen gas cooling tube 17 and provided along the outside of the first hydrogen gas outlet pipe 16b in the axis direction.

In addition, a cooling medium inlet pipe 20a which penetrates the lid 13 and inlets a low-temperature cooling medium for cooling brine from the lower portion manifold 20 to each cooling medium tube 18 for cooling brine, and a cooling medium outlet pipe 19a which outlets the low-temperature cooling medium for cooling brine from the upper portion manifold 19 are provided. The cooling medium inlet pipe 20a is provided in the inner circumference of the cooling medium tube 18 between the first hydrogen gas inlet pipe 16a, the second hydrogen gas inlet pipe 17a, the first hydrogen gas outlet pipe 16b and the second hydrogen gas outlet pipe 17b in the axis direction.

Although, for the low-temperature cooling medium for cooling brine, a liquefied gas such as liquefied nitrogen can also be employed, the running cost can be preferably reduced by employing chlorofluorocarbon or the like for refrigerators (not illustrated) using a refrigeration cycle.

The first and second hydrogen gas cooling tubes 16,17, the upper portion manifold 19 and the lower portion manifold 20 and the plurality of cooling medium tube 18 for cooling brine are arranged concentrically centering on the rotation axis 14 arranged on the axis of the container 12 in a planar view in the order from inside mentioned below: the first and second hydrogen gas cooling tubes 16,17, a plurality of cooling medium tubes 18 for cooling brine; the upper portion manifold 19 and the lower portion manifold 20 are formed in a circle shape centering on the rotation axis 14.

Between the inner surface of the lid 13 and the liquid surface of brine, a gas-phase portion for dealing with thermal expansion of brine is provided, as well as, a dry gas supply pipe 26a which constantly supplies the gas-phase portion with a dry gas for preventing deterioration of brine and a dry gas discharge pipe 26b which emits the supplied dry gas are provided penetrating the lid 14.

Next, examples of how the heat exchanger 11 is used for filling a fuel tank of an automobile with hydrogen gas will be explained. First, valves of the dry gas supply pipe 26a and the dry gas discharge pipe 26b are opened to fill the gas-phase portion with a dry gas; valves of the cooling medium inlet pipe 20a and the cooling medium outlet pipe 19a are opened to inlet a liquid cooling medium expanded at an expansion valve (not illustrated) of an refrigerator or a low-temperature gaseous cooling medium which is generated by evaporation of the liquid cooling medium into the cooling medium tube 18; brine is cooled by exchanging heat between low-temperature cooling medium in a low-temperature cycle and the brine via the cooling medium tube 18, as well as, brine in the container 12 is cooled to a preset brine cooling temperature by rotating the propeller 15 by an air motor, not illustrated, via the drive shaft 24, the speed reducer 25 and the rotation axis 14. When the temperature of brine reaches the brine cooling temperature, the refrigerator is stopped to interrupt inlet of the low-temperature cooling medium into the cooling medium tube 18, as well as, the air motor is stopped to interrupt circulation of brine and the heat exchanger 11 is made in a standby state. When the temperature of brine in the standby state rises up to the preset upper limit temperature, the refrigerator and the air motor are operated again to cool brine to the brine cooling temperature.

When a fuel tank of an automobile is filled with a high-pressure hydrogen gas which is compressed in advance, the valves of the first hydrogen gas inlet pipe 16a and the second hydrogen gas inlet pipe 17a are individually opened; hydrogen gas from a source of hydrogen gas supply is individually supplied to lower ends of the first hydrogen gas cooling tube 16 and the second hydrogen gas cooling tube 17, and at the same time, the refrigerator and the air motor are operated to resume cooling of brine and circulation of brine. The supplied hydrogen gas rises up in the first hydrogen gas cooling tube 16 and the second hydrogen gas cooling tube 17 exchanging heat with precooled brine to be cooled to a predetermined temperature and is outlet to the first hydrogen gas outlet pipe 16b and the second hydrogen gas outlet pipe 17b, and fills the fuel tank via a piping for filling.

By providing the container 12 filled with brine with the helical hydrogen gas cooling tubes 16, 17 and the cooling medium tube 18 for cooling brine, a conventional brine storage tank and piping and pump for circulating brine can be omitted, whereby downsizing of hydrogen gas cooling facilities can be attained. By providing the rotation axis 14 which is arranged in the axis direction of the container 12 with the propeller 15 and circulating brine in the container 12, heat exchange between a low-temperature cooling medium flowing in the cooling medium tube 18 and brine and heat exchange between hydrogen gas flowing in the hydrogen gas cooling tubes 16, 17 and brine can be efficiently performed, and each heat exchange efficiency can be improved, whereby downsizing of the heat exchanger 11 can be attained.

Since the lid 13 is provided with all of the rotation axis 14, the first hydrogen gas inlet pipe 16a, the second hydrogen gas inlet pipe 17a, the first hydrogen gas outlet pipe 16b, the second hydrogen gas outlet pipe 17b, the cooling medium inlet pipe 20a, the cooling medium outlet pipe 19a, the dry gas supply pipe 26a and the dry gas discharge pipe 26b, there is no need to process on the peripheral wall of the container 12 for connecting a piping, and joining and assembly of each piping can be performed at the lid 13, whereby manufacturing of the heat exchanger 11 can be easily performed and the production cost can be reduced. Further, maintenance of the heat exchanger 11 can be easily performed by discharging brine in the container 12 from the drain 22 and removing the lid 13, whereby reduction in the maintenance cost can be attained. By precooling brine and making the heat exchanger 11 in a standby state, hydrogen gas can be effectively cooled from the beginning of filling of hydrogen gas.

Although, in the above-mentioned embodiment, the gas-phase portion is constantly supplied with a fresh dry gas, it may be filled with a dry gas in advance. Although nitrogen gas is the best for the dry gas, inert gases other than nitrogen or a dry air can also be used.

In addition, although, in the above-mentioned embodiment, the hydrogen gas cooling tube has a vertically two-stage structure, the tube can be arranged in a vertically three- or more stage structure depending on the conditions such as the height of the container, and can also be arrange in a vertically one-stage structure. The coil diameter of the helix of the hydrogen gas cooling tube varies depending on the flow rate of hydrogen gas, the size of the tube or the like, and generally the coil diameter is preferably in the range of 100 mm to 500 mm; the pitch of the helix is preferably in the range of 5 mm to 32 mm.

Although, in the above-mentioned embodiment, an air motor is employed for driving the drive shaft, an electric motor can also be used. The propeller varies depending on the length of the hydrogen gas cooling tube, and while a plurality of the propellers is preferably provided, only one propeller may also be provided.

Further although, in the above-mentioned embodiment, the upper portion manifold and the lower portion manifold are provided and a plurality of straight tube-shaped cooling medium tubes are arranged, each manifold can be omitted by making the cooling medium tube in the same helical shape as the hydrogen gas cooling tube.

By using, as the cooling medium tube or the hydrogen gas cooling tube, a fin-attached tube or a tube in which a helical groove is formed on the inner surface thereof, the heat transfer area can be made large, whereby the heat transfer effect can be promoted. By using a tube in which a helical groove is formed on the inner surface thereof, turbulence of fluid flowing in the tube can be promoted and the heat transfer efficiency can be further improved.

REFERENCE NUMERALS

11 . . . heat exchanger, 12 . . . container, 13 . . . lid, 14 . . . rotation axis, 15 . . . propeller, 16 . . . first hydrogen gas cooling tube, 16a . . . first hydrogen gas inlet pipe, 16b . . . first hydrogen gas outlet pipe, 17 . . . second hydrogen gas cooling tube, 17a . . . second hydrogen gas inlet pipe 17a, 17b . . . second hydrogen gas outlet pipe, 18 . . . cooling medium tube, 19 . . . upper portion manifold, 20 . . . lower portion manifold, 21 . . . support leg, 22 . . . drain pipe, 23 . . . fastener, 24 . . . drive shaft, 25 . . . speed reducer, 26a . . . dry gas supply pipe, 26b . . . dry gas discharge pipe

Claims

1. A heat exchanger which cools hydrogen gas with brine cooled by a low-temperature cooling medium characterized by comprising:

a vacuum insulated container with which brine is filled;

a lid which closes the upper portion opening of the container;

a rotation axis arranged in the axis direction of the container;

a propeller provided along the rotation axis;

a helical hydrogen gas cooling tube arranged around the rotation axis and the propeller; and

a cooling medium tube for cooling brine arranged around the hydrogen gas cooling tube.

2. The heat exchanger according to claim 1, wherein the hydrogen gas cooling tube is provided with a plurality of hydrogen gas cooling tubes having a vertically multistage structure.

3. The heat exchanger according to claim 1, wherein the upper end and the lower end of the cooling medium tube are communicatively connected to an annular upper portion manifold and an annular lower portion manifold, respectively, and a cooling medium is circulated in the cooling medium tube from the lower end to the upper end direction.

4. The heat exchanger according to claim 1, wherein a gas-phase portion between the inner surface of the lid and the liquid surface of brine in the container is supplied with a dry gas.

5. The heat exchanger according to claim 1, wherein a bottom portion of the container is provided with a drain for discharging brine with which the container is filled.

6. The heat exchanger according to claim 1, wherein the container has a vertically long bottomed cylindrical shape and a lower portion of the container is supported with three or more support legs, and the container can be stood by itself with its axis vertical.

7. The heat exchanger according to claim 1, wherein that the low-temperature cooling medium is a low-temperature cooling medium for refrigerators using a refrigeration cycle.

8. A heat exchanger which cools hydrogen gas by brine which is cooled by a low-temperature cooling medium characterized by comprising a vacuum insulated double walled vertically long bottomed cylindrical container which is filled with brine, a disk-shaped lid closing an upper portion opening of the container, a rotation axis which penetrates the center of the lid to be arranged in the axis direction of the container, a propeller provided on the rotation axis, a helical hydrogen gas cooling tube provided around the rotation axis and the propeller, and a plurality of cooling medium tubes for cooling brine which are arranged around the hydrogen gas cooling tube, whose upper ends and lower ends are communicatively connected to an annular upper portion manifold and an annular lower portion manifold, respectively, and through which a cooling medium supplied from a cooling medium inlet pipe communicating the lower portion manifold is discharged from a cooling medium outlet pipe communicating the upper portion manifold, wherein the rotation axis, the hydrogen gas cooling tube, the plurality of cooling medium tubes for cooling brine and the container are concentrically arranged centering on the rotation axis in a planar view in the order from inside mentioned below: the propeller, the hydrogen gas cooling tube, the plurality of cooling medium tubes for cooling brine and the container.

9. A heat exchanger according to claim 8, wherein the low-temperature cooling medium is a low-temperature cooling medium tier refrigerators using a refrigeration cycle.