Cryogenic Cooling Device

Abstract

The present invention relates to a cryo temperature cooling device (1)comprising 5 a tank (2), being filled up at least in part with a coolant (3), and a heat conducting element (4), whereas the heat conducting element (4) can be brought into thermal contact with the coolant (3), so that the coolant has a phase transition occurring below a temperature of −100° C., so that the cryogenic cooling device more or less consumes no coolant during operation.

Description

In the following, the invention is described by using a specific embodiment in the light of the enclosed figures.

The figures show:

FIG. 1 a cross sectional view through the cryo temperature cooling device according to the invention;

FIG. 2 a cross sectional view through the measurement device according to the invention;

FIG. 3 a top view to a portable measurement device according to the invention;

FIG. 4 a further embodiment with a cooling device integrated in the detector; and

FIG. 5 an embodiment with separate radiator coil.

FIG. 1 is a cross sectional view through the cryo temperature cooling device 1 according to the invention. The tank 2 is preferably made from pressure resistant material so that it can withstand the vapor pressure of the coolant 3 both at room temperature as well as at the maximum operation or storage temperature of the cryo temperature cooling device. A tank 2 in addition is made in such a way that it comprises an inner wall 5 and an outer wall 6, having a distance from the inner wall 5 via an intermediate area 7. The intermediate area 7 is filled with heat insulating layers so that tank 2 respectively the cryo temperature cooling device 1 separates the coolant sufficiently from the surrounding temperature and that it remains in the frozen state for a long term of time.

Within the tank 2 the coolant 3 is provided. The substances, coming into question as a coolant for the cryo temperature cooling device 1, stand out by a low phase transition temperature, for example a low melting temperature, being roughly the temperature to which an object is to be cooled, a preferably high heat of fusion, preferably high boiling temperature and a preferably low vapor pressure at the maximum operation/storage temperature. Some of the substances to be considered and their relevant properties are listed in the following, not completed Table 1:

TABLE 1
		Melting		Boiling
		Point	Heat of	Temperature
		TS	Fusion	TSI
Coolant	Formula	[° C.]	[kJ/l]	[° C.]
Pentaborane (11)	B5—H11	−122.0		65.0
Phosphorotioc bromide difluoride	PSBrF2	−136.9		35.5
Trichlorosilane	SiHCl3	−128.2		33.0
Sulfur dichloride	SCl2	−122.0		59.6
1,2,2-Trichloro-1,1-difluoroethane	C2—H—Cl3—F2	−140.0		71.9
1,2,2-Trichloro-1,2-difluoroethane	C2—H—Cl3—F2	−174.0		72.5
1,1-Dichloroethene	C2—H2—Cl2	−122.6	81.5	31.6
Bromoethene, Bromoethylene,	C2—H3—Br	−139.5	71.8	15.8
Vinyl bromide
Acetaldehyde	C2—H4—O	−123.4	41.1	20.1
Ethyl bromide, Bromo ethane	C2—H5—Br	−118.7	54.1	38.4
Ethane thiol	C2—H6—S	−147.9	66.7	35.1
1-Chloropropane	C3—H7—Cl	−122.9	62.8	46.5
1-Propanol	C3—H8—O	−124.4	71.5	97.2
2-Propanethiol	C3—H8—S	−130.5	61.4	52.6
Butane	C4—H10	−138.0	81.2	−0.5
Butene-2 cis	C4—H8	−139.0	130.2	3.7
Ethyl acetylene	C4—H6	−125.7	111.5	8.1
Butene-1	C4—H8	−185.4	68.6	−6.3
Isobutene	C4—H8	−140.0	105.7	−6.9
cis-1,3-Pentadiene	C5—H8	−140.8	57.2	44.1
1,4-Pentadiene	C5—H8	−148.2	59.4	26.0
2-Methyl-1,3-butadiene	C5—H8	−145.9	49.2	34.0
Cyclopentene	C5—H8	−135.0	38.1	44.2
1-Pentene	C5—H10	−165.1	54.3	30.0
cis-2-Pentene	C5—H10	−151.4	66.5	36.9
trans-2-Pentene	C5—H10	−140.2	76.6	36.3
2-Methyl-1-butene	C5—H10	−137.5	73.4	31.2
3-Methyl-1-butene	C5—H10	−168.4	47.5	20.1
2-Methyl-2-butene	C5—H10	−133.7	71.8	38.6
trans-1,2-Dimethylcyclopropane	C5—H10	−149.6		28.2
Ethylcyclopropane	C5—H10	−149.2		35.9
Methylcyclobutane	C5—H10	−161.5		36.3
Pentane	C5—H12	−129.7	72.9	36.1
Isopentane	C5—H12	−159.8	44.3	27.9
2-Pentanethiol	C5—H12—S	−169.0		112.9
Diethylmethylamine	C5—H13—N	−196.0		66.0
4-Methylcyclopentene	C6—H10	−160.8		65.7
1,5-Hexadiene	C6—H10	−140.7		59.4
1-Hexene	C6—H12	−139.8	74.3	63.5
cis-2-Hexene	C6—H12	−141.1	72.0	68.8
Methylcyclopentane	C6—H12	−142.4	61.7	71.8
2,3-Dimethyl-1-butene	C6—H12	−157.3		55.6
Ethylcyclobutane	C6—H12	−142.9		70.8
cis-2-Hexene	C6—H12	−141.1		68.8
3-Methyl-1-pentene	C6—H12	−153.0		54.2
4-Methyl-1-pentene	C6—H12	−153.6		53.9
4-Methyl-trans-2-pentene	C6—H12	−140.8		58.6
2-Methylpentane	C6—H14	−153.6	47.3	60.3
3-Methylpentane	C6—H14	−162.9	40.6	63.3
2,3-Dimethylbutane	C6—H14	−128.1	6.1	57.9
2-Hexanethiol	C6—H14—S	−147.0		142.0
Triethylsilane	C6—H16—Si	−159.0		109.0
1-Heptene	C7—H14	−118.9	88.1	93.6
Methylcyclohexane	C7—H14	−126.6	52.9	100.9
4-Methy-1-hexene	C7—H14	−141.5		86.7
trans-2-Methyl3-hexene	C7—H14	−141.6		85.9
2,2-Dimethylpentane	C7—H16	−123.7	39.1	79.2
3,3-Dimethylpentane	C7—H16	−134.4	47.4	86.1
1-Ethyl-1-methylcyclopentane	C8—H16	−143.8		121.6
3-Methylheptane	C8—H18	−120.5	71.8	118.9
4-Methylheptane	C8—H18	−121.0	66.6	117.7

It is to be understood that Table 1 does not list all coolants to be used according to the invention, but only a selection. Especially, this selection is mainly limited to substances with a boiling temperature T_SI>20° C. and a melting temperature T_S<−120° C. Only butane, butene-2 cis, ethyl acetylene, butene-1 and isobutene have been mentioned in addition, even if their boiling temperature T_SI is lower than 20° C. Suitable as coolants are propane and propene also, but they do have a vapor pressure of 8.7 and 10.3 bar at 21° C., therefore requiring higher standards with regard to the pressure resistance of the tank 2.

As a comparison, liquid nitrogen has a boiling temperature of −196° C. and a heat of fusion of about 161 kJ/ltr. Suitable as coolants are also substances like propane and propene, which nevertheless do have a vapor pressure of already 8.7 respectively 10.3 bar at 21° C. and therefore having to meet higher demands when it comes to the pressure stability of the tank.

Furthermore, a heat conducting element 4 in the form of a cooling finger, protruding from tank 2 through an opening 14 through the inner wall 5 and the outer wall 6, is seen in the cryo temperature cooling device 1. The cooling finger 4 is surrounded nearly completely from the coolant 3 within the tank 5. Mounted to the part of the cooling finger 4, protruding from the cryo temperature cooling device 1, is heat insulating protective cap 8. So, the complete cryo temperature cooling device 1 is isolated from the surrounding temperature as long as it is not in operation respectively not used for the cooling of an object, therefore, being able to be stored. The cooling finger 4 preferably also comprises material, providing for a good heat transfer and at the same time for the thermal connection between coolant and the object to be cooled. It may for example be made from copper. In order to further improve the heat transfer of the coolant 3 to the cooling finger, further substances could be added to the coolant 3 in order to promote this property.

The cryo temperature cooling device is used as follows: the cryo temperature cooling device 1 is charged by bringing the cooling finger 4 to a temperature below the melting point of the coolant. When using vinyl-bromide, this would, for example, be a temperature below −138° C. (135.2 K). This cooling process continues until the coolant is mainly frozen. The cooling, respectively the charging of the cryo temperature cooling device 1, is conducted with a charging device, for example a compression refrigerating machine or with liquid nitrogen.

Afterwards, in order to store the cryo temperature cooling device 1 until it is used for operational purposes, the protecting cap 8 is mounted to the cooling finger 4. Therefore, a good heat insulation of the cryo temperature cooling device 1 with regard to the outside is achieved and the frozen state of the coolant 3 can be kept fairly long.

When the cryo temperature cooling device 1 should be used for cooling purposes, for example of a detector, the protective cap 8 is removed from the cooling finger 4 and the cooling finger 4 is connected to the object to be cooled or included therein.

FIG. 2 shows a cross section at view of a cryo temperature cooling device 1 according to the invention, which might be coupled to a detector 10, comprising a detector support 15, a detector crystal 16, being connected to a preamplifier, also mounted on the detector support 15 and therefore cooled also, as well as an outer wall 20. The outer wall in the embodiment is comprising a window, being mainly transparent for the radiation to be measured, namely a radiation entry window 21.

The cooling finger 4 of the detector 10 is thermally mounted to the detector support 15, supporting also the detector crystal 16, for example a germanium crystal. There are, nevertheless, other detector crystals suitable in order to be cooled by the inventive cryo temperature cooling device 1, for example silicon crystal detectors, CdTe-detectors and others. Preferably, the preamplifier is thermally connected to the detector support 15 also so that this is cooled, too. When the measurement respectively the operation time of the detector 10 has ended, the cryo temperature cooling device 1 can be removed from the detector 10 again in order to be recharged for a further measurement.

As the size of the cryo temperature cooling device 1 is small, it is especially suitable for the operation in combination with a measurement device in the form of a handheld device 11, which is shown schematically in a top view in FIG. 3.

Because of its low weight and volume this handheld device 11 is especially suitable for mobile missions, for example as gamma ray detector for luggage control at airports, borders or at big events. The handheld device 11 is touched at its handle 17 and hold thereon during the measurement. Input keys 12 allow the selection for example of various functions or are designed to start and end the measurement operation. Measurement results may be metered either acoustically, for example when excessing the detected limits, or via reading the display 13.

FIG. 4 shows a further embodiment in which, according to the invention, the cryo temperature cooling device is integrated to the detector, forming one measurement device 9. Thereby the detector, comprising a detector support 15 and a detector crystal 16 including pre-amplifier, the heat conducting element 4 and the inner tank 5 together with the coolant 3 are forming a fixed mounted device. Thereby, the heat conducting element 4 and the detector support 15 can be made from one piece. The inner tank 5 is made to withstand pressure in this embodiment, so that it can withstand the vapor pressure of the used coolant at the maximum operating temperature.

Via a connection 18, which may be protected and isolated by a removable heat insulating cap 8, it is possible—after removal of cap 8—to “load” the cryo temperature cooling device as described above, that is it could be cooled, by keeping the heat conducting contact of the connection 18 at a temperature T until the detector is cooled and the coolant is mainly frozen. For the temperature T it is true that T<T_P, whereby T_P is the phase transition temperature of the coolant used according to the invention. After removing the charging device from the connection 18 and attaching the protection cap 8, the detector is kept cooled for several hours ready for operation.

FIG. 5 shows another embodiment, at which the “charging” occurs not via the heat conducting element 4, but via a cooling coil 19 mounted within the inner tank 5. Instead of the heat conducting element 4, the cooling coil 19 is led to the connection 18, so that during the “charging process” the coolant 3 is cooled via the cooling coil 19.

The use of cooling coil 19 for the charging of the cryo temperature cooling device 1 is especially an advantage when cooled (liquefied) gases, for example nitrogen or helium or others, liquid coolants are available for the cooling process. Those cooled (liquefied) gases or coolants could then be piped directly through the inner part of the cooling coil, which allows for a higher heat transport so that the cooling can take place faster. Furthermore, the connections 18 of the cooling coil, being directed to the outside, may consist of materials, being bad heat conductors, so that the heat insulation of the cryo temperature cooling device with regard to the surrounding is improved, so that the operation time can even be improved with regard to the device shown in FIG. 4.

In addition to the use for the cooling of detectors, the cryo temperature cooling device according to the invention can be used in any devices where cryo temperatures are necessary or wanted. This is especially true for, but not limited to further measurement applications, not the least for such applications, using superconductors, especially high Tc superconductors. One has to think firsthand to electronics, here especially to noise sensitive preamplifiers, to IR sensors, night vision devices, to SQUIDs or to applications for radar.

LIST OF REFERENCES

1 cryo temperature cooling device

2 tank

3 coolant

4 heat conducting element

5 inner wall (inner tank)

6 outer wall (outer tank)

7 intermediate space

8 protecting cap

9 measurement device

10 detector

11 handheld device

12 input key

13 display

14 opening

15 detector support

16 detector crystal, eventually with preamplifier

17 handle

18 connection

19 cooling coil

20 outer wall of the detector

21 radiation entry window

Claims

1. Cryo temperature cooling device comprising a tank, being filled up at least in part with a coolant, and a heat conducting element, whereas the heat conducting element can be brought into thermal contact with the coolant, characterized in that the coolant has a phase transition occurring below a temperature of −100° C., so that the cryogenic cooling device more or less consumes no coolant during operation.

2-25. (canceled)

26. Measurement device, comprising a detector and a cryo temperature cooling device according to claim 1 for cooling the detector, comprising at least one of the following features: the measurement device is set up as a portable handheld device,the measurement device is set up as a spectrometer,the detector comprises a semiconductor detector, preferably using germanium, for the measurement of ionizing radiation,at least one cooling finger of the cryo temperature cooling device is in thermal contact to the detector.

27-41. (canceled)

42. Cooling device for the cooling down of a cryo temperature cooling device according to claim 1, characterized in that the cooling device for the cooling down of the cryo temperature cooling device can be connected thermally with said cryo temperature cooling device and where the cooling down is provided mainly via said thermal connection and mainly without material exchange between cooling device and the cryo temperature cooling device to be cooled down.

43. (canceled)

44. (canceled)