JPH0349020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a helium refrigerator, and more particularly to a regenerator-type helium refrigerator comprising a regenerator-type expander and a heat exchanger.

[Background of the invention]

Conventional helium refrigerators, especially small-capacity ones with a refrigerating capacity of 10W or less at 4.5K, generally combine a regenerator type expander and a heat exchanger. A typical configuration thereof will be explained with reference to FIGS. 1 and 2.

In Figure 1, 1 is an expander that expands high-pressure helium gas supplied from a compressor (not shown) to generate cold, 2 is a high-pressure gas supply pipe, and 3 is a gas that returns the expanded gas to the compressor. 4 is the first stage expander, 5 is the second stage expander, 6 is the first heat exchanger, 7 is the second heat exchanger, 8 is the third heat exchanger, 9 is the Joule Thomson valve (can also be an expansion valve), 10
1 is a first cold station, 11 is a second cold station, 12 is a radiation shield, 13 is a condensing heat exchanger, 14 is a liquid helium container, 15 is a vacuum cold storage tank, 16 is a high pressure gas supply pipe, and 17 is a low pressure gas return pipe It is. Such a helium refrigerator is disclosed in US Pat. No. 4,277,949 and the like.

Further, to explain the structure of the heat exchanger using the first heat exchanger 6 as an example, in FIG. A laminate made by alternately stacking and bonding spacers (plastic, etc.), 19,2
0 is a header, 21 is a vessel for storing the laminate 18, 22 and 23 are bellows for absorbing the difference in longitudinal shrinkage between the laminate 18 and the vessel 21, and 2
4 and 25 are ventilation holes, 26 and 27 are spaces, 28 is a sealing material that prevents bypass flow of low pressure gas, and 29
30 is a high pressure gas pipe, and 30 is a low pressure gas pipe. Such a heat exchanger is disclosed in Japanese Utility Model Application No. 57-127172.

Next, to explain the operation and function of such a helium refrigerator, the expander 1 receives high pressure helium gas from the high pressure gas supply pipe 2 and adiabatically expands it, thereby generating cold. The station 10 and the second cold station 11 are made low temperature. The adiabatically expanded gas returns to the compressor through the gas return pipe 3.

On the other hand, while the high-pressure gas supplied from the high-pressure gas supply pipe 16 passes through the first heat exchanger 6, it exchanges heat with the gas in the low-pressure channel flowing oppositely, and its temperature decreases.
It is sent to the first cold station 10. Here, it is cooled by the cold generated by the first stage expander 4, and the temperature drops and enters the second heat exchanger 7. While passing through the second heat exchanger 7, the gas exchanges heat with the gas in the low-pressure flow path that flows opposite to it, lowers its temperature, and is sent to the second cold station 11. Here, the heat is further cooled by the cold generated by the second stage expander 5, and the temperature drops and enters the third heat exchanger 8. In the process of passing through the third heat exchanger 8, the temperature also decreases by exchanging heat with the low pressure gas flowing oppositely, and finally reaches 10K or less and reaches the Joule-Thompson valve 9. When passing through the Joule-Thompson valve 9, the low-temperature, high-pressure helium gas expands adiabatically to become low-temperature and low-pressure, and is liquefied by the Joule-Thompson effect.

After being liquefied, the gas-liquid mixed fluid enters the condensing heat exchanger 13, where it exchanges heat with the vaporized gas in the liquid helium container 14, recondensing the vaporized gas outside the tube, and at the same time recondensing the vaporized gas inside the tube. It vaporizes and sequentially passes through the low-pressure gas channels of the third heat exchanger 8, second heat exchanger 7, and first heat exchanger 6, and while cooling the high-pressure gas flowing in the opposite direction, its temperature rises, and finally When the temperature reaches room temperature, the gas returns to the compressor via the low-pressure gas return pipe 17.

In addition, the inside of the vacuum cold storage tank 15 is
It is maintained at a vacuum pressure of 10 ^-6 Torr or less, and has the effect of reducing heat intrusion from the outside to the low-temperature part due to gas convection. The radiation shield 12 similarly functions to reduce heat intrusion due to radiation from the wall surface of the vacuum cold storage tank 15 at room temperature to the low-temperature part, and is used to reduce the heat intrusion due to radiation from the wall surface of the room-temperature vacuum cold storage tank 15 to the low-temperature end of the first stage expander 4 and the low-temperature end of the first heat exchanger 6. Generally, cooling is performed by bringing the heat exchanger into contact with the heat exchanger 6 or the piping between the first heat exchanger 6 and the second heat exchanger 7, or the like.

Such conventional helium refrigerators have the following drawbacks. That is, between multiple heat exchangers,
The piping that connects the heat exchanger and the expander is complicated, which increases production costs, and the increased number of piping connections increases the chance of gas leaks, reducing reliability. Ta. Particularly in small-capacity helium refrigerators, such drawbacks are fatal.

[Purpose of the invention]

An object of the present invention is to provide a helium refrigerator that has a simple structure and high reliability by eliminating piping that communicates between heat exchangers and between a heat exchanger and an expander.

[Summary of the invention]

The present invention provides an expander that generates cold by adiabatic expansion of high-pressure helium gas, and an intermediate header that is separated from the expander and has a flow path for return low-pressure helium gas and high-pressure helium gas. In a helium refrigerator having a plurality of heat exchangers connected through Eliminating piping that connects between heat exchangers and between the heat exchanger and the expander,
The structure is simplified and reliability is increased.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. First, to explain the configuration, 31 is an expander, 32 is a high pressure gas supply pipe to the expander 31 supplied from a compressor (not shown), and 33 is a gas for returning low pressure gas after expansion to the compressor. Return pipe, 34
is the first stage expander, 35 is the second stage expander, 36 is the first heat exchanger, 37 is the second heat exchanger, 38 is the third heat exchanger, 39 is the Juul-Thompson valve, 40 is the first Cold station, 41 is a second cold station, 42 is a radiation shield, 43 is a condensing heat exchanger, 44 is a liquid helium tank, 45 is a vacuum cold storage tank, 46 is a high pressure gas supply pipe to the first heat exchanger 36, 47 is a low-pressure gas return pipe from the first heat exchanger 36 to the compressor, 48 is a normal temperature side header of the first heat exchanger 36, 49 and 50 are intermediate headers provided between the heat exchangers, and 51 is a third heat exchanger. 52 is a thermal connector connecting the first cold station 40 and the intermediate header 49; 53 is a thermal connector connecting the second cold station 41 and the intermediate header 50.

Next, the operation will be explained. The normal temperature, high pressure gas sent to the high pressure gas supply pipe 46 is sent to the first heat exchanger 36 via the normal temperature side header 48. 1st
In the process of passing through the heat exchanger 36, it is cooled by the low pressure gas flowing oppositely, and the temperature drops and the intermediate header 4
Enter 9. Since the intermediate header 49 is cooled by the cold generated by the first stage expander 34 via the thermal communication body 52, the temperature of the high pressure gas decreases when passing through the intermediate header 49, and the high pressure gas is transferred to the second heat exchanger 37. to go into. Similarly, in the second heat exchanger 37, the low-pressure gas flowing oppositely is cooled and sent to the intermediate header 50 with a reduced temperature. The intermediate header 50 is the thermal connector 5
3, the high-pressure gas is cooled by the cold generated by the second-stage expander 35, so the high-pressure gas is cooled here as well and enters the third heat exchanger 38, where it is cooled by the low-pressure gas flowing oppositely to the final The target becomes less than 10K and reaches Juul-Thomson valve 39. When passing through the Joule-Thompson valve 39, the low-temperature, high-pressure helium gas undergoes adiabatic expansion, becomes low-temperature and low-pressure, and liquefies due to the Joule-Thompson effect.

After being liquefied, it enters the condensing heat exchanger 43, where it re-condenses the vaporized gas in the liquid helium container 44 and at the same time vaporizes itself into the third heat exchanger 38,
It passes through the low-pressure flow path of the second heat exchanger 37 and the first heat exchanger 36, and while cooling the high-pressure gas flowing oppositely, the temperature of the high-pressure gas itself rises, and finally reaches room temperature and passes through the low-pressure gas return pipe 47. Back to the compressor.

The feature of this embodiment is that three heat exchangers are integrated via two intermediate headers.
Another feature is that the number of piping has been minimized, and another feature is that a flexible heat exchanger, such as a copper mesh band, is used to transfer heat from the expander to the heat exchanger tube, and the surface is vapor-deposited with aluminum to prevent heat intrusion due to radiant heat transfer. By using a connecting body, the helium gas piping that connects the expander system and the heat exchanger system can be eliminated.

According to this embodiment, a plurality of heat exchangers are connected via intermediate headers, and the cold generation part of the expander and the intermediate header of the heat exchanger are connected via a flexible thermal link. Therefore, there is no need for gas piping to connect between the heat exchangers or between the expander and the heat exchanger, and flexible thermal interconnects are used to connect the cold generation part of the expander and the intermediate header of the heat exchanger. The structures can be easily connected, which simplifies the structure, and also eliminates gas leaks caused by poor piping connections, improving reliability.

FIG. 4 shows another embodiment of the present invention.
To explain the specific structure of the heat exchanger 36, 54 is an outer cylinder part, 55 is a laminate in which porous heat exchanger plates and spacers are alternately stacked and bonded, 56 is a bellows connected to a part of the outer cylinder part, 57 and 58 are gas vents.

In this case, the bellows 56 absorbs the difference in the amount of longitudinal shrinkage between the laminate 55 and the outer cylindrical portion 54 .

According to this embodiment, since it is only necessary to connect the bellows 56 to a part of the outer cylindrical portion 54, the structure is simpler than that of the conventional example shown in FIG. Since they are joined, there is an effect that bypass flow of low pressure gas does not occur.

FIG. 5 shows still another embodiment of the present invention, in which a thermal link 52 connects the first cold station of the first expander 34 and the intermediate headers of the first heat exchanger 36 and second heat exchanger 37. and a second cold station, a second heat exchanger 37, and a third heat exchanger 38
The expansion machine and the heat exchanger group can be assembled separately by dividing the fasteners 61, 62, 63, and 64 in order to fix the thermal connecting body 53 connecting the intermediate headers around the cold station and the intermediate header, respectively. After that, the thermal interconnects 52 and 53 can be attached or removed individually, which has the effect of facilitating assembly work.

〔Effect of the invention〕

According to the present invention, by connecting a plurality of heat exchangers via an intermediate header and connecting the cold generation part of the expander and the intermediate header of the heat exchanger with a flexible thermal connecting body, It is possible to eliminate the piping that connects the heat exchangers and between the heat exchanger and the expander, and it is also possible to easily connect between the cold generation part of the expander and the intermediate header of the heat exchanger, which reduces the structure. Not only is it easy to do, but it also has the effect of improving reliability by reducing the number of piping connections.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing the configuration of a conventional regenerator-type helium refrigerator, Fig. 2 is a sectional view of a laminated heat exchanger applied to a conventional helium refrigerator, and Fig. 3 is a system diagram according to the present invention. FIG. 4 is a system system diagram showing one embodiment of the configuration of a regenerator-type helium refrigerator; FIG. 4 is a partial sectional view of an integrated laminated heat exchanger showing another embodiment of the helium refrigerator according to the present invention; FIG. FIG. 2 is a side view showing a state in which a thermal connecting body connecting an expander and a heat exchanger is installed, showing still another embodiment of a helium refrigerator according to the present invention. 31... Expander, 40... First cold station, 41... Second cold station, 3
6...First heat exchanger, 37...Second heat exchanger, 3
8... Third heat exchanger, 49, 50... Intermediate header, 52, 53... Heat communication body.

Claims (1)

[Scope of Claims] 1. An expander that generates cold by adiabatic expansion of high-pressure helium gas, and a flow path provided separately from the expander for return low-pressure helium gas and high-pressure helium gas. a plurality of heat exchangers connected through intermediate headers, and an expansion valve that adiabatically expands high-pressure helium gas cooled by the heat exchanger and leads it to liquefaction, 1. A helium refrigerator, characterized in that a cold generation part of the refrigerator and an intermediate header of the heat exchanger are connected via a flexible thermal link. 2. The helium refrigerator according to claim 1, wherein the thermal communication body is detachably connected to at least one of the cold generation part of the expander or the intermediate header of the heat exchanger.