JPH0418187B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cryogenic refrigerant container for storing a cryogenic refrigerant such as liquid helium.

[Prior Art] As is generally known, a large amount of energy is required to produce, for example, liquid helium. Therefore, it is usually stored in cryogenic refrigerant containers. As this type of ultra-low temperature refrigerant container, a multilayer shield container shown in FIG. 5 of the attached drawings and a container shown in FIG.
The multilayer shield container shown in the figure uses a heat insulation method called the super insulation method, in which a shield plate C is wrapped with a film with poor thermal conductivity between the inner cylinder A and the outer cylinder B. is provided. The container shown in FIG. 6 is a gas shield container that utilizes the sensible heat of liquid nitrogen. It has become possible to considerably suppress the intrusion of heat into the ultra-low temperature refrigerant container by such heat insulation methods such as super insulation and gas shielding. An example of such a conventional technique is the one described in Japanese Utility Model Application Publication No. 52-6476.

[Problems to be Solved by the Invention] Incidentally, in such conventionally proposed cryogenic refrigerant containers, the largest amount of heat enters through the connecting pipe between the inner cylinder and the outer cylinder. Therefore, the sensible heat of helium is normally used to reduce the amount of heat entering through this connecting pipe. That is,
As the evaporated cold helium slowly rises up the connecting pipe, it exchanges heat with the pipe wall and dissipates the incoming heat to the outside, thereby minimizing the amount of heat intruding. However, since the helium in this connecting pipe is almost stationary, heat exchange with the pipe wall is not efficient.

In order to improve the efficiency of this heat exchange, as shown in Figure 6, the top of the connecting pipe D is covered with a lid E, and a thin pipe F is wrapped around the connecting pipe D. Let the cold gas flow out. As a result, as the cold gas ascends through the narrow pipe F, the temperature of the cold gas increases through heat exchange, and is then discharged to the outside.

However, even if such means are used, heat exchange in the connecting pipe is not sufficient, and low-temperature evaporated gas is thrown away to the outside. As a result, much needed cold energy is not efficiently used to prevent heat from entering.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the conventional ultra-low temperature refrigerant container by using a so-called ion wind to spread evaporated gas from inside the inner cylinder between the inner cylinder and the outer cylinder. It is an object of the present invention to provide a cryogenic refrigerant container which is brought into positive contact with the wall of a connecting pipe and efficiently exchanges heat on the wall of the connecting pipe.

By the way, in ion wind, when a high voltage is applied to the surface facing a needle-shaped or thin wire-shaped positive electrode, the gas existing between this electrode and the above-mentioned surface is ionized, and these ions is accelerated toward the negative pole by an electric field, and the collision between ions and neutral gas molecules causes the entire gas to flow toward the negative pole.

It is known that this ionic wind promotes the heat transfer of the gas to the negative electrode side, for example.
The heat transfer characteristics in the case of _N22 gas are shown in Figure 8 (A.
Yabe etal：Proc.6th Int.Heat Transfer
Couf., 3 (1978) 171). In Figure 8, the vertical axis represents the heat transfer coefficient, the horizontal axis represents the discharge current,
This amount is proportional to the speed and size of the ion wind. That is, as the discharge current increases, the heat transfer coefficient increases.

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, a heat insulating material is inserted between the inner cylinder and the outer cylinder, and the inner cylinder and the outer cylinder are connected. In an ultra-low temperature refrigerant container in which refrigerant is taken in and out through a connecting pipe, a plurality of heat exchange promoting chambers are provided along the entire length of the connecting pipe, and each heat exchange promoting chamber is placed close to the wall surface of the connecting pipe. An electrode is provided, each adjacent heat exchange promoting chamber communicates with each other through a narrow passage at its outer periphery, and the connecting pipe is connected to the negative terminal of the high voltage power source, and the electrode provided in each heat exchange promoting chamber is connected to the high voltage power source. are connected to the positive terminals of the connecting pipes, respectively, and are configured to generate ionic wind in each heat exchange promotion chamber that causes refrigerant gas generated from the refrigerant in the inner cylinder to flow toward the wall surface of the connecting pipe.

Each heat exchange promoting chamber may be constituted by a donut-shaped container provided around the outer periphery of the connecting pipe, or alternatively may be defined by insulator plates spaced within the connecting pipe.

[Function] In the ultra-low temperature refrigerant container according to the present invention configured as described above, the electrode provided in each heat exchange promotion chamber is used as a positive electrode, the connecting pipe is used as a negative electrode, and a high voltage is applied, thereby creating a connection between the electrode and the wall surface of the connecting pipe. The gas existing between them is ionized, the generated ions are accelerated toward the wall of the connection pipe on the negative electrode side, and an ion wind directed toward the wall of the connection pipe is generated in each heat exchange promotion chamber. The ion wind generated in this way causes the refrigerant gas in the connecting pipe or a thin pipe provided separately to flow toward the connecting pipe wall, thereby efficiently exchanging heat between the refrigerant gas and the connecting pipe wall. ing. Note that the current to be supplied to each electrode and the connecting pipe to generate the ion wind is selected so as to generate the ion wind without causing an electric discharge.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

1 and 2 show an embodiment of the present invention, in which heat exchange promoting chambers are provided in five stages around the outer circumference of the connecting pipe over the entire length thereof. In Figures 1 and 2, 1 represents a part of the inner cylinder of the container, 2 represents a part of the outer cylinder, and the heat insulating material packed between the inner cylinder 1 and the outer cylinder 2 is omitted in the drawings. ing. Reference numeral 3 denotes a connecting pipe extending between the inner cylinder 1 and the outer cylinder 2, which is used to take in and take out the refrigerant in the inner cylinder 1, into which a transfer tube or the like (not shown) is inserted. Connection pipe 3
A lid 4 is attached to the upper end of the holder. Reference numeral 5 denotes a heat exchange promoting section, which is attached to the outer circumferential wall of the connecting pipe 3 and passes through the donut-shaped container 6 and each donut-shaped container 6 constituting the heat exchange promoting chamber from the inner tube 1 to the outside of the outer tube 2. Each donut-shaped container 6 has a thin pipe 7 through which refrigerant gas evaporated from the refrigerant in the inner tube 1 passes.
Inside, as shown in FIG. 2, a ring-shaped thin wire 9 is arranged close to the outer periphery of the connecting pipe 3 using the high-voltage current introduction terminal wire 8 as a support. The diameter of each narrow pipe 7 is preferably as small as possible to prevent backflow of refrigerant gas therethrough, but may be selected to ensure adequate refrigerant gas flow. For the same reason, each thin pipe 7 is connected to a portion of the donut-shaped container 6 where the refrigerant gas flow is weak, that is, an outer portion, as shown in FIG. A high voltage is applied to the terminal 10 of each high voltage current introducing terminal line 8 and the terminal 11 connected to the connecting pipe 3 with the polarity shown.
As a result, in each donut-shaped container 6, the second
As shown by arrows in the figure, ion wind is generated toward the outer peripheral wall of the connecting pipe 3, promoting heat exchange by the refrigerant gas. In this case, connect the ionic wind pipe 3
In order to concentrate on the outer circumferential wall of the connecting pipe 3, the ring-shaped thin wire 9 may be placed close to the outer circumferential wall of the connecting pipe 3, but it is necessary to separate it to an extent that does not cause abnormal discharge.

FIGS. 3 and 4 show another embodiment, and the first
Parts corresponding to the containers of the embodiment of FIG. 2 and FIG. 2 are designated by the same reference numerals. In this embodiment, the heat exchange promoting section 1
2 is provided inside the connecting pipe 3, that is, a lead wire 13 is provided at the center of the connecting pipe 3, and a ring-shaped thin wire 14 and an insulating plate 15 made of Teflon, ceramic, etc. are attached to this lead wire 13 as shown in the figure. They are installed alternately at intervals. Each insulator plate 15 prevents electrical contact between the connecting pipe 3 and the lead wire 13, and together with the inner wall of the connecting pipe 3 constitutes a heat exchange promotion chamber to prevent refrigerant gas from entering the upper and lower heat exchange sections. It works to prevent a decrease in heat exchange efficiency. Therefore, the gap between each insulator plate 15 and the connecting pipe 3 is made as narrow as possible without interfering with the flow of refrigerant gas. Further, the ring-shaped thin wires 14 are positioned as close as possible to each other in order to concentrate the ion wind on the inner wall of the connecting pipe 3, as in the embodiments of FIGS. 1 and 2. The lead wire 13 and the connecting pipe 3 are connected to a positive terminal 16 and a negative terminal 17, respectively, as shown in FIG.
A high voltage is applied to these terminals. As a result, an ionic wind is generated within the connecting pipe 3 toward the inner wall thereof, and heat exchange between the refrigerant gas rising within the connecting pipe 3 and the inner wall of the connecting pipe 3 is promoted.

In the illustrated embodiment, a ring-shaped thin wire is used as the positive electrode, but a radially extending needle-like electrode may also be used. In the embodiments shown in FIGS. 3 and 4, each insulator plate 15 may be configured to contact the inner wall of the connecting pipe 3, and each insulator plate 15 may be provided with holes through which the refrigerant gas passes. Furthermore, if necessary, the embodiments of FIGS. 1 and 2 and the embodiments of FIGS.
It is also possible to combine the embodiments shown in the figures to promote heat exchange from both the outer and inner walls of the connecting pipe 3.

[Effects of the Invention] As explained above, in the ultra-low temperature refrigerant container of the present invention, an ionic wind is generated that causes the refrigerant gas generated from the refrigerant in the inner cylinder to flow toward the wall surface of the connecting pipe, and the refrigerant gas Since the structure is configured to promote heat exchange on the wall surface of the connecting pipe by the refrigerant gas in the inner cylinder, heat exchange on the wall surface of the connecting pipe by the refrigerant gas evaporated from the refrigerant in the inner cylinder is effectively carried out, and thereby It is possible to reduce the amount of heat that enters. As a result, the evaporation loss of the internal refrigerant can be kept small. In addition, since ion wind can be generated with very small current energy, it is extremely important from an energy saving perspective to be able to reduce the evaporation loss of refrigerants such as liquid helium, which require a large amount of energy to produce. That's true.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG.
The figure is an enlarged partial sectional view of the main part of the device in Figure 1,
The figure is a schematic diagram showing another embodiment of the present invention, FIG. 4 is an enlarged partial sectional view of the main part of the device in FIG.
The figures are schematic diagrams showing different conventional ultra-low temperature refrigerant containers, Figure 7 is a schematic diagram showing the principle of generation of ion wind, and Figure 8 is a graph showing heat transfer characteristics in _N22 gas by ion wind. In the figure, 1: inner cylinder, 2: outer cylinder, 3: connection pipe,
6: heat exchange promotion chamber, 7: thin pipe, 9: ring-shaped thin wire, 14: ring-shaped thin wire, 15: insulator plate.

Claims (1)

[Claims] 1. An ultra-low temperature refrigerant container in which a heat insulating material is inserted between an inner cylinder and an outer cylinder, and refrigerant is taken in and out through a connecting pipe connecting the inner cylinder and the outer cylinder. , a plurality of heat exchange promotion chambers are provided along the entire length of the connection pipe, each heat exchange promotion chamber is provided with an electrode close to the wall surface of the connection pipe, and each adjacent heat exchange promotion chamber is connected to its outer periphery. The connecting pipes are connected to the negative terminal of the high-voltage power source, and the electrodes provided in each heat exchange promotion chamber are connected to the positive terminal of the high-voltage power source. An ultra-low temperature refrigerant container characterized in that it is configured to generate ionic wind in each heat exchange promotion chamber that causes refrigerant gas to flow toward the wall surface of the connecting pipe. 2. According to claim 1, each heat exchange promoting chamber is constituted by a donut-shaped container provided around the outer periphery of the connecting pipe, and the refrigerant gas is made to flow toward the outer wall surface of the connecting pipe. Ultra-low temperature refrigerant container. 3. According to claim 1, each heat exchange promoting chamber is defined by an insulating plate disposed at intervals inside the connecting pipe, and the refrigerant is caused to flow toward the inner wall surface of the connecting pipe. Ultra-low temperature refrigerant container as described.