U.S. patent application number 13/413678 was filed with the patent office on 2012-09-27 for cooling device with controllable evaporation temperature.
Invention is credited to Markus Mayer, Franco Sestito.
Application Number | 20120240610 13/413678 |
Document ID | / |
Family ID | 46052213 |
Filed Date | 2012-09-27 |
United States Patent
Application |
20120240610 |
Kind Code |
A1 |
Sestito; Franco ; et
al. |
September 27, 2012 |
Cooling device with controllable evaporation temperature
Abstract
A cooling device for cooling a test sample has at least two
cascade cooling stages, each with at least one coolant line, one
compressor (1.1, 2.1), one relief throttle (1.5), one evaporator
(6, 7) and one liquefier (3, 6). The coolant line is divided into n
partial lines (A, B) between the compressor (2.1) and the liquefier
(6) of the last cascade cooling stage, wherein n.gtoreq.2. Each
divided n partial line (A, B) has a valve (2.7, 2.8) and an
individual relief throttle (2.5, 2.6). The divided partial lines
(A, B) are connected to the evaporator (7) of the last cascade
cooling stage. This represents a simple possibility of adjusting
the cooling temperature without using valves that must be adjusted
in a cold state, since such valves are complex and expensive.
Inventors: |
Sestito; Franco;
(Winterthur, CH) ; Mayer; Markus; (Gossau,
CH) |
Family ID: |
46052213 |
Appl. No.: |
13/413678 |
Filed: |
March 7, 2012 |
Current U.S.
Class: |
62/335 |
Current CPC
Class: |
F25B 7/00 20130101; F25B
6/00 20130101; F25B 2400/0403 20130101 |
Class at
Publication: |
62/335 |
International
Class: |
F25B 7/00 20060101
F25B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 25, 2011 |
DE |
10 2011 006 174.6 |
Claims
1. A cooling device for cooling a test sample, the cooling device
comprising: at least one first cascade non-final cooling stage,
said first non-final cooling stage having at least one first
coolant line, a first compressor, a first relief throttle, a first
evaporator and a first liquefier; and a second final cascade
cooling stage, said second final cascade cooling stage having at
least one second coolant line, a second compressor, a second relief
throttle, a second evaporator and a second liquefier, said second
coolant line being divided into n partial lines between said second
compressor and said second liquefier, wherein n.gtoreq.2, said
divided n partial lines structured for individual blockage thereof
and independently of an other by means of at least n-1 valves, each
divided partial line having an individual relief throttle, wherein
said divided partial lines are connected to said second
evaporator.
2. The cooling device of claim 1, wherein said divided partial
lines are guided in parallel through said second liquefier.
3. The cooling device of claim 1, wherein said second evaporator is
designed as a heat exchanger, a gas to be cooled entering said heat
exchanger through a gas inlet, dissipates heat, exits said heat
exchanger again through a gas outlet and is guided to the test
sample for cooling thereof.
4. The cooling device of claim 1, wherein the cooling device is
structured for use in a nuclear magnetic resonance spectroscopy
apparatus.
5. The cooling device of claim 1, wherein the cooling device is
structured for use in an X-ray spectroscopy apparatus.
6. The cooling device of claim 1, wherein the cooling device is
structured for use in an EPR apparatus.
Description
[0001] This application claims Paris Convention priority of DE 10
2011 006 174.6 filed Mar. 25, 2011 the complete disclosure of which
is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] The invention concerns a cooling device for cooling a test
sample, comprising at least two cascade cooling stages, each
comprising at least one coolant line, one compressor, one relief
throttle, one evaporator and one liquefier.
[0003] Devices having such properties are e.g. the device NMR90 of
the company Millrock Technology, Kingston, N.Y., USA, the device
ULSP90 of the company ULSP bv, Ede, NL and the device FTS XR Air
Jet of the company RototecSpintec GmbH, Biebesheim, Germany.
[0004] Various analysis methods require cooling of the samples to
be analyzed. In specific cases, such as nuclear magnetic resonance
spectroscopy or X-ray crystallography, this is often achieved by
introducing the sample into a cold gas flow, advantageously
nitrogen or helium.
[0005] This cold gas flow may be realized e.g. through evaporation
of liquid gases or cooling a warm gas using heat exchangers that
are immersed into liquefied gas. Provision or generation and
storage of these liquefied gases requires complex logistics.
[0006] The warm gas may alternatively also be cooled using a
coolant cycle process. In a cycle process, a suitable coolant is
compressed in a compressor to a higher pressure and is thereby
heated, then cooled (desuperheated) in a heat exchanger to a
temperature below the liquefaction temperature that prevails at the
obtained pressure, thereby dissipating heat, is further liquefied,
thereby dissipating further heat, is relieved by a suitable
throttle to a lower pressure, and evaporated again in a second heat
exchanger, thereby absorbing heat from the gas to be cooled at the
low evaporation temperature.
[0007] There are conventional configurations of coolant cycle
processes with adjustable evaporation pressure and adjustable
throttle between the first heat exchanger (coolant liquefier) and
second heat exchanger (coolant evaporator) in order to adjust the
desired cooling temperature. Such a configuration is technically
complex when the cycle process to be varied is already operated in
a cascade of cycle processes at a very low liquefaction temperature
and the adjustable throttle consequently also becomes very
cold.
[0008] For this reason, it is current practice to largely do
without adjustment of the desired coolant temperature. This applies
to the devices of the companies Bruker (type "BCU-X"), ULSP type
"90 Immersion Probe Cooler", and Milrock type "NMR90 sample
cooler". In an alternative fashion, the gas flow that has been
cooled to a predetermined temperature is heated to a desired higher
temperature by means of an installed heating device. One example
therefore are the devices of the company RototecSpintec FTS "XR
Air-Jet Cooler".
[0009] It is the underlying purpose of the present invention to
provide a simple way of adjusting the cooling temperature without
using valves that must be adjusted in a cold state, since these are
complex and expensive.
SUMMARY OF THE INVENTION
[0010] This object is achieved in a surprisingly simple and yet
effective fashion in that the coolant line is divided into n
partial lines between the compressor and the liquefier of the last
cascade cooling stage, wherein n.gtoreq.2, the divided n partial
lines can be blocked individually and independently of each other
by means of at least n-1 valves, the divided partial lines each
comprise their own relief throttle, and the divided partial lines
are both connected to the evaporator of the last cascade cooling
stage.
[0011] In the inventive cooling device, the compressed coolant is
divided into two or more parallel paths upstream of the first heat
exchanger (liquefier) and guided in this fashion through the
liquefier, through a separate respective throttle and to the second
heat exchanger (evaporator). When the individual paths are
selectively individually blocked by the valves thereof, one obtains
an overall adjustable throttle effect. 2.sup.n-1 different throttle
effects can be adjusted for n valves when the individual throttles
are properly dimensioned. At least one valve has to be open at any
time, and for this reason, one valve can be omitted. One then
obtains 2.sup.n different throttle effects with n valves and n+1
coolant paths with each throttle. The coolant is evaporated,
thereby providing the desired cooling power in the second heat
exchanger at the evaporation temperature of the coolant at this
influenceable pressure, and for this reason, the cooling
temperature can also be influenced.
[0012] In contrast to the conventional devices, the throttles of
this device need not be adjustable themselves, which could be
realized only with great technical expense in a cascade of cycle
processes of a cycle process to be varied with a very low
liquefying temperature and therefore low throttle temperature.
[0013] One particularly preferred embodiment of the inventive
cooling device is characterized in that the divided partial lines
are guided in parallel through the liquefier.
[0014] One further advantageous embodiment is characterized in that
the evaporator of the last cascade cooling stage is designed as a
heat exchanger, a gas to be cooled enters the heat exchanger
through a gas inlet, dissipates heat and exits the heat exchanger
again through a gas outlet, and the cooled cooling gas is guided to
the test sample for cooling it. With this design, the heat
exchanger is simultaneously the transfer line for the cooling gas
and the device can be designed in a simple and space-saving
fashion.
[0015] The invention is particularly advantageous when the cooling
device is part of a nuclear magnetic resonance spectroscopy
apparatus, in which the cooled gas flow is heated to the desired
temperature and higher temperatures can be achieved with less
cooling and therefore also less heating, which simplifies
control.
[0016] The inventive cooling device may alternatively also be part
of an X-ray spectroscopy apparatus. In particular, X-ray
crystallography often requires cooling of the test samples.
[0017] The inventive cooling device is alternatively also
advantageously part of an EPR apparatus.
[0018] Further advantages of the invention can be extracted from
the description and the drawing. The features mentioned above and
below may be used individually or collectively in arbitrary
combination. The embodiments shown and described are not to be
understood as exhaustive enumeration but have exemplary character
for describing the invention.
BRIEF DESCRIPTION OF THE DRAWING
[0019] FIG. 1 shows a schematic view of an embodiment of the
inventive cooling device.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] The cooling device shown by way of example in FIG. 1
includes a first cascade cooling stage with compressor 1.1, safety
pressure switch 1.2, filter 1.3, relief throttle 1.5, and pressure
compensating vessel 1.4, and also a second cascade cooling stage
with compressor 2.1, safety pressure switch 2.2, filter 2.3, and
pressure compensating vessel 2.5.
[0021] A combined air heat exchanger with fan 5 is e.g. used as
liquefier 3 for the first cascade cooling stage and as
desuperheater 4 for the second cascade cooling stage.
[0022] A heat exchanger 6 is used as evaporator for the first
cascade cooling stage and as liquefier for the second cascade
cooling stage.
[0023] A heat exchanger 7, illustrated by way of example as
transfer line, is used as evaporator for the second cascade cooling
stage to provide the desired cooling power in that a gas to be
cooled is guided from the inlet 7.1 to the outlet 7.2.
[0024] Downstream of the compressor 2.1 of the second cascade
cooling stage, the coolant line of the illustrated embodiment is
divided into two partial lines A, B. These are guided in parallel
through the heat exchanger 6 downstream of the respective valves
2.7, 2.8. Each of the partial lines A, B, has its own relief
throttle 2.5, 2.6. The two partial lines A, B, are subsequently
guided into the heat exchanger 7. The evaporation temperature can
then be controlled via connecting or disconnecting a partial line
A, B, by means of the valves 2.7, 2.8.
[0025] Although the invention is illustrated above by means of a
cooling device in accordance with the principle of a compression
cooling machine with two-stage cooling cascade, adjustment of the
evaporation temperature by dividing the coolant path upstream of
the first heat exchanger into two or more paths is also possible
with one-stage cooling devices according to this principle and also
with cooling cascades with more than two stages.
[0026] List of Reference Numerals [0027] 1.1 compressor of the
first cascade cooling stage [0028] 1.2 safety pressure switch
thereof [0029] 1.3 filter thereof [0030] 1.4 compensating vessel
thereof [0031] 1.5 relief throttle thereof [0032] 2.1 compressor of
the second cascade cooling stage [0033] 2.2 safety pressure switch
thereof [0034] 2.3 filter thereof [0035] 2.4 compensating vessel
thereof [0036] 2.5 relief throttle A thereof [0037] 2.6 relief
throttle B thereof [0038] 2.7 valve to the relief throttle A
thereof [0039] 2.8 valve to the relief throttle B thereof [0040] 3
liquefier of the first cascade cooling stage [0041] 4 desuperheater
of the second cascade cooling stage [0042] 5 fan for liquefier 3
and desupercooler 4 [0043] 6 heat exchanger as evaporator of the
first cascade cooling stage and liquefier of the second cascade
cooling stage [0044] 7 heat exchanger as evaporator of the second
cascade cooling stage for providing the cooling power by cooling a
gas [0045] 7.1 entry of the gas to be cooled [0046] 7.2 exit of the
cooled gas
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