DE1451092A1 - Device for throttling the refrigerant supply in evaporators to generate the lowest temperatures - Google Patents

Description

MAX-PLANCK-GESELLSCHAFT for the Promotion of Science e.V. 1 /. Γς 1 Π Q O

File 4922

new description P IH 51 092.0

August 23, 1968

Device for throttling the refrigerant supply in evaporators to generate extremely low temperatures ^ __> ________-_____ ^ _ ^ -.

The invention relates to a device for throttling the supply of refrigerant in evaporators for generating extremely low temperatures, especially with helium vaporizers.

Temperatures below the boiling point of a refrigerant are generally generated by reducing the refrigerant Pressure evaporates. Temperatures below 4.2 ° K can be advantageous with a working on the principle of the helium evaporator Device (DAS 1 151 264) are generated, in which the liquid inflow into the evaporator by a depending is metered by the temperature of the evaporator controlled valve element, the pressure in the evaporator by means of a in the suction line arranged manostats is kept constant. Although this device is for continuous automatic Operation suitable, but only for temperatures below ' the boiling point of the refrigerant, d. H. in the case of helium for temperatures below 4.2 K.

For use cases where e.g. B. a sample without interruption of operation, which is associated with undesirable warming to room temperature, both at temperatures above as well as to be examined at temperatures below 4.2 ° K, the device mentioned is unsuitable because the Generation of temperatures above 4.2 K is not possible. In such cases, there has so far been a need for one Change between evaporator for temperatures above 4.2 ° K (Kältetechnik 13 (1961) 250-251) and evaporator for temperatures below 4.2 ° K (DAS 1 151 264).

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{Art. / a; , - ^, «,, ^ i, _f . ι jjau 3 of the change. ν »4 * It.

In contrast, the present invention enables the production of temperatures below 4, K 2 ⁰ with the previously suitable only for the production of temperatures to 4 ₉ 2 ° K HeIiumverdämpfer. The characteristic of the invention can be seen in the fact that a throttle section consisting of a plurality of capillaries is arranged in the supply pipe for the liquid refrigerant, that the capillary tubes are inserted into a common fastening element and can be exchanged with this as a structural unit, and that the capillary tubes are different, preferably have gradually decreasing lengths after the immersion side.

The helium vaporizer is a device for the continuous evaporation of liquid helium, in which a supply pipe immersed in the liquid supply opens into the interior of a hollow vaporizer body and this interior is connected to a pumping device via a suction line which has a control valve that controls the suction power controls the pumping device as a function of the temperature at a selected measuring point in the region of the evaporator body. Such an evaporator arrangement can be placed directly on a storage vessel and, with efficient consumption of the low-boiling liquid serving as refrigerant, enables constant temperatures to be maintained up to near the boiling point of helium

For current pumping device and open control valve, the liquid helium increases _in: up Zuleitungsrohr- and enters the The resulting ■ Gas' interior of the evaporator hollow body "The liquid containing the desired cooling vaporized here and causes''is angesäugt from the vacuum pump and optionally in a gas container ^ f orders. ; '■ -:' ■ '■> ■■ - ■ - ■: · -

Has the evaporator or "the held him sample äiif ¹ ^ cooled the required Temperstur, the Kältemii is: - · ^c telstrom regulated by the evaporator hollow body with the aid of controlled in dependence on the temperature control valve so j that the temperature at the lowest Refrigerant consumption remains as constant as possible.

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With such a device, any temperatures between room temperature and 4.2 ° K can be set and maintained constant, but not below ^ 2 ⁰ K. Substituting but forming the subject of the invention throttle section liquid in such a device in the feed pipe for the a refrigerant, both temperatures above 4.2 ° K can also be produced as below 4.2 ⁰ and K are held constant. In the range below ** .2 ° K, the refrigerant supply is essentially determined by the dimensioning of the throttle section and the control valve is used to set and maintain the desired temperature by keeping the corresponding negative pressure in the evaporator system constant.

Such a device offers the advantage that temperatures in the range of room temperature can now be generated up to below **, 2 ° Κ with one and the same device, d. H. is possible without interrupting operations.

An exemplary embodiment of the subject matter of the invention is shown in the drawings. Show it:

Figure 1 is a schematic section through the on a

Helium storage vessel arranged evaporator Figure 2 shows a section through a section of the Feed pipe for the liquid refrigerant with an exchangeable capillary bundle.

As FIG. 1 shows, the evaporator 1 is located in a housing 2, 3 which can be evacuated and which, with the aid of a holder · + is placed directly on a helium storage vessel 5. A supply pipe for the liquid refrigerant extends downwards 6 to the bottom of the helium storage vessel 5. At the top, the feed pipe 6 opens into the inner cavity of the actual Cooling head of the evaporator 1. At the top of this cavity is a copper pipe spiral 7 connected, which in tight Windings outside around the cooling head running downwards

-H-

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and serves as radiation protection. Via a control valve 8, which is controlled via a temperature sensor 9 arranged in the area of the evaporator system 1, 7, the spiral has 7 Connection to a vacuum pump 10, the pressure side 11 in connection with the helium gas container, not shown stands. The helium storage vessel 5 is connected via the connection 12 also connected to the gas tank.

Figure 2 shows on an enlarged scale that about the O-ring screw connection 6M- in the jack insert the not shown Helxum storage vessel to be inserted, partly from a vacuum jacket 63 surrounded supply pipe 6 for the liquid refrigerant. A bundle of fine capillaries 61, which of different Length is inserted into a base 62 which is screwed into the supply pipe 6 at the lower end will. -

EXPECTATIONS

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Claims (3)

EXPECTATIONS 1) Device for throttling the refrigerant supply in evaporators for generating extremely low temperatures, in particular helium evaporators, characterized in that in the supply pipe a throttle section consisting of a plurality of capillaries (61) is arranged for the liquid refrigerant (6) is. 2) Device according to claim 1, characterized in that the capillary tubes (61) in a common fastening element (62) are used and interchangeable with this as a structural unit. 3) Device according to claim 1, characterized in that the capillary tubes (61) different, preferably have gradually decreasing lengths after the immersion side. 909811/0620