US20080184711A1 - Method for Cooling a Detector - Google Patents

Method for Cooling a Detector Download PDF

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Publication number
US20080184711A1
US20080184711A1 US12/020,934 US2093408A US2008184711A1 US 20080184711 A1 US20080184711 A1 US 20080184711A1 US 2093408 A US2093408 A US 2093408A US 2008184711 A1 US2008184711 A1 US 2008184711A1
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mixture
volume
pressurized fluid
gas
fluid
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Uwe Hingst
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Diehl Defence GmbH and Co KG
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Diehl BGT Defence GmbH and Co KG
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Priority claimed from DE200710004999 external-priority patent/DE102007004999B4/de
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Assigned to DIEHL BGT DEFENCE GMBH & CO. KG reassignment DIEHL BGT DEFENCE GMBH & CO. KG ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HINGST, UWE
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
    • F25B9/006—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant containing more than one component
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
    • C09K5/02—Materials undergoing a change of physical state when used
    • C09K5/04—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/02—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point using Joule-Thompson effect; using vortex effect

Definitions

  • the invention relates to a method for cooling a detector, in particular an IR detector in the seeker head of a guided missile.
  • the expanding gas after a pressurized fluid has been expanded is used to cool the detector.
  • a method such as this uses the so-called Joule-Thomson effect (also referred to as the Joule-Kelvin effect) for cooling, making use of the expansion of a real gas, which is not the same as that of an ideal gas.
  • Joule-Thomson effect also referred to as the Joule-Kelvin effect
  • a real gas is expanded below its inversion temperature, then it is cooled down because of the positive Joule-Thomson coefficient—that is to say by means of certain interactions between the gas molecules.
  • This cooling down of the gas to the boiling point of the respective real gas with expansion to about 1 bar below its inversion temperature is made technical use of in a versatile manner in order to produce low temperatures or to cool down temperature-sensitive equipment, in particular such as detectors.
  • optical detectors in the infrared range, so-called IR detectors must be cooled down to temperatures of below 100 K in order to achieve a good signal-to-noise ratio.
  • a suitable pressurization working gas (high-pressure cooling gas) is expanded by means of a restrictor or nozzle, and the emerging gas which has been cooled down by virtue of isoenthalpy expansion is used to reduce the temperature of the gas inlet and of a detector that is disposed adjacent to the expansion nozzle.
  • the expanding and partially liquefying gas is aimed directly against the detector rear wall to be cooled, or against a thermally highly conductive intermediate wall to which the emerging gas can be applied and on whose front face the detector is arranged.
  • the working gas which is supplied on the high-pressure side to the expansion nozzle also referred to as a restrictor—to be cooled down by flowing in the opposite direction to the inlet working gas, which is being expanded, through an appropriate reverse-flow heat exchanger before finally emerging into the surrounding area.
  • open Joule-Thomson coolers are known for confined operational conditions such as these, in which the pressurized working gas is emitted to the surrounding area from a high-pressure gas container after it has been expanded, after the required detector cooling and after flowing back in the reverse-flow heat exchanger.
  • Open Joule-Thomson coolers such as these are used, for example, to cool IR detectors in the seeker heads of guided missiles where neither physical space nor energy are available to allow a compressor system to be used for a closed Joule-Thomson cooler.
  • a two-stage, open Joule-Thomson cooler for cooling an IR detector in the seeker head of a guided missile is described, for example, in European patent specification EP 0 432 583 B1 and U.S. Pat. No. 5,150,579.
  • detector cooling-down times of less than 1.5 to 2 seconds must be achieved by means of the Joule-Thomson cooler from the restricted high-pressure bottle volumes of a few cubic centimetres, but at high gas pressures.
  • This is the situation, for example, with portable surface-to-air missiles against enemy combat aircraft (so-called “Manpads”—Manportable Air Defense Systems—and with marine missile defense systems (against so-called Seaskimmers—missiles approaching at low level) and enemy combat aircraft.
  • a combination of a considerably shorter cooling-down time of the IR detector with a longer cooler running time and greater cooling loads to be transported away from the IR detector must be achieved from these small bottle volumes at the same time.
  • a method of cooling a detector which comprises:
  • the pressurized fluid being a mixture of argon or nitrogen as a main component and at least one alkane as a secondary component, the mixture forming a positive azeotrope;
  • this object is achieved according to the invention in that a gas mixture which forms a positive azeotrope, in which the boiling point of the mixture is below that of the pure components, including argon or nitrogen as a main component and at least one alkane as a secondary component, is expanded as the fluid.
  • the invention is in this case based on the consideration that the cooling gases that have been used until now with boiling points below 90 K, such as nitrogen, argon, oxygen or air, do not have sufficient cooling capacity for the desired running time extension.
  • the cooling gases that have been used until now with boiling points below 90 K, such as nitrogen, argon, oxygen or air, do not have sufficient cooling capacity for the desired running time extension.
  • Their cooling capability that is to say the integral Joule-Thomson coefficient—is simply too low.
  • the inversion temperatures are below room temperature, of about 25° C.
  • the invention is based on the consideration that certain gases, inter alia those with a relatively high molar mass, such as the alkanes, admittedly have considerably greater cooling capacities in terms of the Joule-Thomson effect, but their boiling points are all above 100 K. It is therefore impossible to use pure alkanes as a cooling gas for cooling the IR detector to temperatures of at least 100 K.
  • the invention recognizes the fact that the characteristic of a high cooling capacity with regard to the Joule-Thomson effect and a desired low boiling point taking into account the gas-mixture thermodynamics can be achieved only in a gas mixture having a plurality of components.
  • Specific real gas mixtures which form a so-called positive azeotrope that is to say they have mixture boiling points below the boiling temperatures of the individual pure components in the T,x diagram, exist only in a few specific cases in particular because of specific interactions between the individual components.
  • a vapor pressure curve plotted over the concentration ratio of the components on a p,x diagram with a specific composition also has a local maximum.
  • x represents the concentration, T the temperature and p the pressure.
  • the boiling curve and vapor-pressure curve touch one another in the phase diagram.
  • the gas mixture behaves like a pure gas.
  • a mixture of this composition is referred to as an azeotrope or as an azeotropic mixture: on boiling or condensation, azeotropic mixtures behave like a pure substance.
  • mixtures are composed to form positive azeotropic mixtures, in which the vapor-pressure curves have a maximum, all these positive-azeotropic mixtures, with these very specific compositions, have boiling points which are well below those of the individual pure gas components.
  • this azeotropic mixture boils like a pure gas at this reduced mixture boiling point, which remains constant, without any change to the mixture composition.
  • an azeotropic point with a specific concentration no longer occurs, in accordance with the Gibb's phase rule, but a two-dimensional or multiple-dimensional “field/region” with specific concentration areas which can be determined precisely for the individual gas components. Since azeotropic mixtures are pressure-dependent, the respective azeotropic mixture must be determined for the pressure ranges that occur in the vapor area, around 1 to 3 bar (0.1-0.3 MPa).
  • a mixture comprising argon or nitrogen (possibly also air) as a main component and at least one alkane as a secondary component, with the alkane or alkanes being chosen such that the mixture forms a positive azeotrope (with a boiling point of below 100 K), behaves like a pure gas with one of the main components in comparison to the higher boiling-point components of the alkanes in the region with the low boiling points, in only specific concentration ratios which comprise the tightly limited azeotropic composition, for cooling of an open Joule-Thomson cooler.
  • a dynamic equilibrium comprising a liquid phase and a gas phase of the azeotropic mixture at the temperature that corresponds to the boiling point of this liquid/gas phase is created in the expansion area (vapor area) downstream from the expansion nozzle.
  • the gas mixture comprising main and secondary components is chosen such that this results not only in a positive-azeotropic gas mixture but that the respective mixture boiling point is as far as possible below 100 K.
  • a mixture composed of gas and liquid for cooling the detector is formed after the expansion process in the vapor area (wet vapor region).
  • the essential feature in this case is that a relatively large amount of liquid and a relatively small amount of gas are produced over wide pressure ranges (from 3 to 50 MPa) since the amount of liquid determines the cooling capability of the cooler arrangement mainly by means of the vaporization enthalpy of this azeotropic mixture.
  • the liquid phase which is produced in the vapor area is changed continuously to the gas phase at a constant boiling point.
  • the cooler performance is in this case governed mainly by the mixture vaporization enthalpy, and less by the pure convective gas cooling.
  • the expanded gas like the gas which is created in the vaporizing amount of liquid as well, flows through the reverse-flow heat exchanger out of the vapor area into the surrounding area, in order to initially cool the high-pressure inlet.
  • the gas phase from the vapor area is finally dissipated to the exterior as consumed gas mixture.
  • these azeotropic mixtures with the main components of nitrogen or argon make use of the greater cooling capacity of an alkane as a secondary component in comparison to nitrogen or argon, by virtue of the higher Joule-Thomson coefficients, that is to say cooling capacities.
  • the higher molar mass of most of the alkanes that are used here is also used such that an even longer running time of the Joule-Thomson cooler can be achieved overall, with the same volumetric amount of pressurized fluid.
  • the expression of fluid in the pressure vessels means the aggregate state of the pressurized gas mixture above the critical point on a T,s diagram, at which no separation of liquid from gas is evident, that is to say there is no meniscus.
  • T represents the temperature and s the entropy.
  • the individual gas components nitrogen, argon and the various alkanes have a maximum in their cooling capacity at one specific pressure, that is to say Joule-Thomson coefficient, which is generally in the range from 200 to 400 bar (20-40 MPa) at room temperatures.
  • Joule-Thomson coefficient which is generally in the range from 200 to 400 bar (20-40 MPa) at room temperatures.
  • the individual gas components exist in the mixture only below their partial pressure, which is below the total pressure, corresponding to the gas-mixture composition.
  • the gas mixtures in the high-pressure bottle must thus be at a higher total pressure in order to optimize the cooling process in order to ensure that the individual gas components, at their partial pressure, approach the region of optimum cooling performance as much as possible. This may necessitate pressures of up to 500 bar and possibly even of 800 bar in the pressure vessels. Higher pressures also at the same time mean greater available amounts of gas in the gas container and therefore additionally a longer cooler running time, as well.
  • alkanes also offers the advantage that, as a result of the higher Joule-Thomson coefficients, the cooling process collapses only at considerably low residual pressures in a high-pressure supply, thus resulting in longer cooler running times in comparison to nitrogen and argon, since the gases that remain in the high-pressure bottle can be used down to lower pressures for cooling purposes.
  • alkanes furthermore offers the advantage that a large number of organic impurities which originate, for example, from gas production, from compression or from a pressure bottle or from pipeline systems, are dissolved in the gas and therefore cannot be precipitated adjacent to the expansion restrictor, and therefore cannot end the cooling process by blocking the restrictor.
  • the boiling point of the azeotrope should be below 100 K, in particular below 90 K.
  • the vapor pressure curve of the selected gas mixture on the p,x diagram it is sufficient in this case for the vapor pressure curve of the selected gas mixture on the p,x diagram to have a mixture-specific local maximum.
  • the boiling point of the mixture on the T,x diagram then has a minimum and is below that of the pure gases that are involved.
  • the sought mixture In order to prevent a component in the mixture from freezing during expansion of the gas mixture, which results in a temperature reduction, and which to this extent can lead to undesirable accumulation on the expansion nozzle, it is advantageous for the sought mixture to be chosen from main and secondary components such that the required azeotropic gas mixture also has a composition in the vicinity of the eutectic composition. For this purpose, it is absolutely essential for the various gas components to be soluble in one another in the liquid, condensed phase.
  • component a is soluble in component b in a dual mixture
  • component c is soluble in at least one of the components a and b in a mixture of three items
  • component d is soluble in at least one of the components a, b and c, etc.
  • the mixture composition must also be designed so as to create a eutectic in order that the boiling point of the fluid that is completely in solution assumes a lower freezing point temperature than the associated boiling point of the mixture.
  • a mixture with a eutectic composition of its components is, specifically, characterized in that the melting point of the mixture is lower than the melting points of the pure components. This is also an important precondition for use of azeotropic mixtures in Joule-Thomson coolers, since the freezing and melting points of the individual alkanes used here are higher than the boiling point of the azeotropic gas mixture with these alkanes.
  • the proposed azeotropic gas mixture must preferably also have a eutectic composition: in the case of the gas mixtures proposed here, the mixture melting point must preferably remain below the mixture boiling point.
  • No individual solid aggregate state may occur in the mixture liquid phase, that is to say no individual components are deposited adjacent to the expansion nozzle.
  • Mixed phases in which one of the components is in the liquid phase and the other component is in the solid aggregate state, do not exist for a mixture with a eutectic composition. If the azeotrope thus has a composition in the vicinity of the eutectic composition, then this prevents individual components from freezing, for example the secondary components in the mixture, significantly reducing the proportion of the component which freezes out.
  • a melting point of below 90 K, or even better below 85 K is advantageous for a eutectic composition of the sought mixture.
  • IR detectors are cooled using gas mixtures which in combination with one another achieve two or all three of the following effects at very high gas pressures and with limited available high-pressure gas containers, by virtue of the higher Joule-Thomson coefficients associated with them:
  • the fluid preferably has an initial pressure of more than 100 bar, in particular of more than 300 bar, in particular of more than 500 bar, and in particular preferably more than 800 bar from a compressed-gas container of limited availability applied to it, in order that the partial pressures of the individual gas components are in the optimum pressure range for their respective cooling capacity.
  • the maximum initial pressure to be provided is therefore governed by the individual gases, their molar components in the mixture and thus their various partial pressures.
  • the total pressure should be chosen as a function of the gas composition such that the specific partial pressures of the individual gases come as close as possible to the maximum specific Joule-Thomson coefficient. This necessarily leads to quite high initial pressures for the gas mixture.
  • the amount of stored fluid is increased by appropriately high compression, with a positive effect on the running time of the Joule-Thomson cooler.
  • a pressure of up to more than 500 bar (in some cases even of up to 800 bar) can be applied in a compact form to the fluid by use of a high-pressure gas bottle.
  • Pressure bottles with a maximum filling pressure of 350 bar are available without problems as standard equipment, and pressure bottles of up 800 bar are even available for trials purposes.
  • a mixture comprising 30 to 70% by volume of nitrogen and 20 to 80% by volume of methane is used as a fluid. Even this simple mixture results in operating temperatures of an IR detector to be cooled of below 100 K and extends its running time by a factor of 2, in comparison to the use of pure nitrogen.
  • Ethane is preferably added as a further secondary component to this fluid, making up a proportion of 10 to 40% by volume.
  • the other components that is to say nitrogen and methane, in this case make up proportions of 20 to 40% by volume and 10 to 40% by volume, respectively.
  • the boiling point remains below 100 K here, although the running time extension is in this case more than a factor of three.
  • a mixture comprising 30 to 70% by volume of nitrogen, 15 to 35% by volume of ethane and 15 to 35% by volume of propane has been found to be another suitable mixture for use as the fluid.
  • a proportion of 10 to 30% by volume of methane can be added to this mixture, as a further component.
  • the other components that is to say nitrogen, ethane and propane, in this case make up proportions of 20 to 70% by volume, 10 to 25% by volume and 10 to 20% by volume, respectively.
  • a mixture comprising 45 to 60% by volume of argon and 35 to 50% by volume of methane is used as the fluid.
  • the azeotrope in this mixture which has a composition of 56% by volume of argon and 44% by volume of methane, admittedly has a slightly higher boiling point of about 96 K than argon (argon has a boiling point of 87.3 K), but the boiling point has been reduced sufficiently in comparison to methane such that a wet vapor mixture of the azeotropic composition occurs in the expansion area, with a boiling point of below 100 K.
  • compositions described there are, however, specified for use in a cooling circuit with low compression pressures, in particular for closed circuits with a maximum pressure of 30 bar. It is not possible to predict their characteristics when used in non-equilibrium conditions in an open Joule-Thomson cooler.
  • the pressurized fluid is therefore temperature-stabilized. This is achieved, for example, by means of heating mats or integrated heating elements, Peltier elements or by means of existing dissipative heat sources, such as electronics, in which case, by way of example, heat tubes can be used for heat transport.
  • Temperature-stabilizing elements such as these are used in particular when the cooling power losses that occur as a result of the pressure loss cannot be compensated for in situ by the ambient temperature, which is low in any case. If temperature stabilization takes place, then the pressure loss in the real mixture can be compensated for, thus leading to a further increase in the running time of the Joule-Thomson cooler.
  • the Joule-Thomson effect with the gases that are used increases as the temperatures become lower. The pressure drop in the case of a relatively cool environment can be compensated for once again by this effect (partially).
  • additional temperature stabilization of the pressure vessel with a relatively cool Joule-Thomson cooler will then additionally contribute to a further running-time extension.
  • the heating means to be used for temperature stabilization must necessarily be arranged such that they act on the pressure bottle.
  • heating mats or the like can surround the pressure bottle.
  • heating elements When heating elements are used for temperature stabilization, they can lead to a pressure increase as the pressure in the pressure bottle decreases, and they can therefore be used to increase the cooling performance of the Joule-Thomson cooler. This is achieved in particular by the heating elements heating the pressurized fluid above the ambient temperature. A value of about 50° C. has been found to be particularly suitable for this purpose in practice.
  • the expanded gas flows in the opposite direction to that before it was expanded, in order to cool the pressurized fluid.
  • This refinement results in the initially mentioned reverse-flow cooling, with the fluid which is supplied to the high-pressure side of the expansion nozzle or restrictor being cooled down by the returning gas flowing in the opposite direction through an appropriate reverse-flow heat exchanger, before finally emerging into the environment.
  • a further pressurized fluid is expanded, with the expanding gas of the further fluid being used to cool the pressurized fluid before it is expanded.
  • This measure results in a multistage Joule-Thomson cooler with the fluid that is used to cool the detector exchanging heat with the expanding gas and the further fluid cooled down in this way, before emerging from the expansion nozzle.
  • This initial cooling means that the fluid which is used to cool the detector can be cooled down to a very low temperature even before it is expanded, as a result of which the further reduction in its temperature that results from this expansion process in comparison to the inversion temperature results in an improvement in the cooling performance.
  • the fluid which is used for cooling can be precooled by the first expansion stage to such an extent that, at the low temperature which then occurs adjacent to the expansion nozzle or restrictor, the subsequent isoenthalpy expansion results in a specific cooling power which is sufficiently great that the detector is cooled down from room temperature to the required detector temperature of below 100 K within a short time.
  • This two-stage embodiment of the cooler makes it possible in particular to achieve cooling times for cooling down from 295 K to below 100 K of less than two seconds. The latter is now a requirement for guided missiles whose IR detectors must be cooled down to the operating temperature within this time in order, for example, to make it possible to detect targets flying at supersonic speed, sufficiently quickly.
  • the fluid which is used for cooling is precooled even before it is expanded, there is no longer any need to carry out additional precooling by means of a reverse-flow heat exchanger using the returning expanded gas.
  • the fluid which has been expanded and has been cooled down to its boiling point can be sprayed onto the rear face of the detector to be cooled, during the expansion process, in the form of a spray coolant. The latter allows a cooler design without any mechanical link to a moving detector.
  • the temperature of the fluid can be reduced further before its expansion by the expanded gas of the further fluid flowing in the opposite direction to that before it was expanded, in order to cool the pressurized fluid.
  • the fluid which is used for cooling not only makes thermal contact with the vapor area of the first expansion stage before its expansion, but its inlet is additionally cooled by the expanded gas of the further fluid flowing back.
  • the expanded gas of the further fluid flows in the opposite direction to that before it was expanded, also in order to cool the pressurized further fluid.
  • methane and in particular tetrafluoromethane can be used as the further fluid for the first cooler stage.
  • argon can also be used for the same reason.
  • Argon has a cooling capacity that is greater than that of nitrogen by a factor of 1.5.
  • the mixture as described above and which forms a positive azeotrope comprises argon or nitrogen as a main component and at least one alkane as a secondary component, is also used for the further fluid, because of the low temperatures that can be achieved and the high cooling capacity.
  • the described refinements and compositions can likewise preferably be used for the mixture.
  • FIG. 1 is a schematic view of a Joule-Thomson cooler
  • FIG. 2 is a cross section taken through the technical implementation of a Joule-Thomson cooler
  • FIG. 3 is a graph illustrating the enthalpy profile during the expansion process in an open Joule-Thomson cooler.
  • FIG. 4 is a schematic view of a two-stage Joule-Thomson cooler.
  • FIG. 1 the schematic shows the design of an open Joule-Thomson cooler 1 for cooling an IR detector 2 .
  • a pressurized fluid flows from a pressure bottle or pressure tank 4 via an inlet valve 6 to an inlet path 7 to a counter-flow or reverse-flow cooler 10 .
  • the temperature of the fluid is thereby decreased in comparison to the temperature in the pressure bottle 4 , by means of the cooler return 14 .
  • the pressurized fluid is expanded via a restrictor 11 which, in particular, is in the form of a nozzle.
  • the expanding gas enters an expansion area or vapor area 13 where it is cooled down as a consequence of the expansion process.
  • Gas of the composition of the gas phase flows out of the expansion area via a return path 14 through the reverse-flow cooler 10 , cooling the fluid as it flows in. After passing through the return path 14 , the expanded gas is exhausted to the environment through an outlet 18 .
  • FIG. 2 shows a cross section of a technical implementation of an open, flow-controlled Joule-Thomson cooler 1 ′.
  • the IR detector 2 to be cooled adjoins the inner wall of a Dewar vessel 19 .
  • the interior of the Dewar vessel 19 is evacuated, thus providing good thermal insulation with respect to thermal conduction and radiation to the environment.
  • a connecting stub 20 extends into the internal area of the Dewar vessel 19 and is provided with a flange 22 for attachment.
  • a gas supply line 23 is arranged in the connecting stub 20 and is connected to a pressure bottle in order to supply with a pressurized fluid.
  • the pressurized fluid flows along the lines which helically surround the connecting stub 20 and form the inlet path 7 , to the expansion nozzle 11 where the fluid is expanded.
  • the emerging gas expands into the expansion area 13 .
  • Gas in the gas phase flows out of the expansion area 13 via the lines which form the inlet flow path, thus forming the return path 14 , and are passed to the exterior of the upper end of the Dewar vessel 19 .
  • the inlet flow is therefore cooled by the flow in the opposite direction.
  • FIGS. 1 and 2 The method of operation of an open Joule-Thomson cooler as shown in FIGS. 1 and 2 will be explained by means of the temperature-entropy graph (for argon as an example) illustrated in FIG. 3 .
  • the graph shows the states which occur during the expansion process in the Joule-Thomson cooler, annotated with the letters “A” to “D”.
  • the associated points are marked in a corresponding manner in the schematic illustration of the Joule-Thomson cooler in FIG. 1 .
  • the entropy of the system is plotted on the abscissa of the graph.
  • the system temperature or system lines of equal enthalpy are marked on the ordinate.
  • the curve profiles of constant enthalpy are also shown on the graph.
  • the fluid flows, as shown in FIG. 1 , through the inlet path 7 , where it is pre-cooled by the expanded and cooled-down gas flowing back in the opposite direction.
  • the pressure along the inlet path 7 to the expansion nozzle 11 can in this case be considered to be constant.
  • the fluid is expanded at the expansion nozzle 11 .
  • the emerging gas expands as shown in FIG. 1 into the expansion area 13 .
  • the gas is cooled down along a curve of constant enthalpy.
  • the system state in this case moves as shown in FIG. 3 from point C to point D in the wet vapor region, with the gas emerging partially in the liquid aggregate state.
  • an amount of liquid in the ratio D-D′′ and a corresponding amount of gas in the ratio D-D′ are produced.
  • the liquid phase exists in accordance with the state point D′ in an equilibrium with the gas phase D′′.
  • the detector 2 which makes thermal contact with the expansion area 13 , is cooled down to a temperature of below 100 K largely by the amount of liquid.
  • the gas flowing out in the return path 14 is heated by heat dissipation from the fluid flowing in the inlet path 7 .
  • a pressure tank was used with a volume of 415 ccm at an initial pressure of 345 bar, and at a temperature of 220.
  • a fluid I with 30% by volume of nitrogen, 30% by volume of methane, 20% by volume of ethane and 20% by volume of propane, as well as a fluid II with a proportion of 30% by volume of nitrogen, 35% by volume of methane and 35% by volume of ethane were investigated as fluid mixtures.
  • the behavior of the fluid mixtures was now investigated in terms of the running time of the Joule-Thomson cooler.
  • the running time was in this case investigated with a pressure bottle at temperatures of ⁇ 54° C., +22° C. and +70° C.
  • a glass Dewar was used as the Dewar vessel 19 as shown in FIG. 2 , in order to analyze the processes in the expansion area 13 .
  • FIG. 4 shows, schematically, the design of a two-stage Joule-Thomson cooler 38 with a fluid which cools an IR detector 80 by means of expansion and comprises a mixture forming a positive azeotrope being initially cooled by expansion cooling of a further fluid.
  • the Joule-Thomson cooler 38 illustrated in FIG. 4 is split, in order to assist understanding, into two coolers 40 and 42 , but these should not be confused with the expansion stages.
  • the first cooler 40 is in this case operated with a mixture, forming a positive azeotrope, from a compressed-gas container 44 .
  • the mixture used in the compressed-gas container 44 is at ambient temperature and at a pressure of 200-500 bar.
  • the mixture is passed by a valve 46 and a straight line 48 running through the cooler 42 to an inlet path 50 of a heat exchanger 51 of the cooler 40 .
  • the first cooler 40 is an expansion cooler with an expansion nozzle or restrictor 52 .
  • the restrictor 52 is connected to the output of the inlet path 50 via a high-pressure line 54 .
  • the high-pressure line 54 is provided with thermal insulation 56 .
  • the second cooler 42 is operated with tetrafluoromethane from a compressed-gas container 58 .
  • the tetrafluoromethane in the compressed-gas container 58 is likewise of ambient temperature and at a pressure of 200-350 bar.
  • the tetrafluoromethane is passed via a valve to the input 62 of an inlet path 64 of a reverse-flow heat exchanger 66 in the second cooler 42 .
  • a line 70 passes from the output 68 of the inlet path 64 of the reverse-flow heat exchanger 66 straight through the second cooler 40 to a restrictor or expansion nozzle 72 .
  • the restrictor 72 is seated at the end of the first cooler 40 that is remote from the second cooler 42 .
  • the tetrafluoromethane which is at high pressure, emerges from the restrictor 72 . In the process, it is expanded and is cooled down.
  • the expanded and cooled-down tetrafluoromethane now flows through a return path 74 through the heat exchanger 51 in the first cooler 40 in the opposite direction to the mixture which is flowing in and forms a positive azeotrope.
  • This mixture is therefore precooled in the first cooler 40 by the expanded tetrafluoromethane wet vapor, but not by the expanded mixture itself.
  • the expanded tetrafluoromethane then flows through a return path 76 through the reverse-flow heat exchanger 66 in the second cooler 42 .
  • the tetrafluoromethane which is flowing in and is at high pressure is precooled by the expanded and cooled-down tetrafluoromethane.
  • the expanded tetrafluoromethane emerges from the return path 76 , at an outlet 78 .
  • the expanding gas from this mixture then emerges from the mount 82 through an aperture 84 .
  • the two coolers 40 and 42 are surrounded by a casing 86 which is closed on the object side by an end wall 88 .
  • the thermally insulated high-pressure line 54 is passed through the end wall 88 .
  • the fluid III as described above and as investigated, and comprising 56% by volume of argon and 44% by volume of methane is particularly suitable for use as a mixture for cooling down the IR detector 80 .
  • This mixture has a boiling point of about 96 K (at 1 bar) and a melting point of less than 75 K.
  • the cooling power is better than that of argon by a factor of about 2.
  • the second expansion stage (associated with the first cooler 40 ) can also be operated with a mixture comprising 30-70% by volume of nitrogen, 15-35% by volume of propane and 15-35% by volume of ethane.
  • a mixture comprising 40% by volume of nitrogen, 30% by volume of propane and 30% by volume of ethane results, in comparison to nitrogen, in a cooling capacity that is about 3 to 7 times greater with a boiling point of only 78 K (at 1 bar). No freezing of the expansion nozzle was found. In comparison to the argon which was also used, the mixed gas resulted in a somewhat higher boiling point, with a cooling capacity that was better by a factor of 2 to 4.5 times.
  • a mixture comprising 20-70% by volume of nitrogen, 20-40% by volume of methane and 10-40% by volume of ethane. Since methane is soluble in liquid nitrogen, ethane is soluble in liquid methane, and ethane and propane are soluble in one another, this mixture has an even better cooling capacity.
  • a mixture comprising 30% molar of nitrogen and 35% molar of methane and ethane, respectively, has a cooling capacity which is 4 to 9 times greater than that of nitrogen.
  • the boiling point of this mixture is about 80 K. This mixture behaves like an azeotropic mixture, and has the characteristics of a virtually eutectic mixture, since no freezing occurs at the low boiling point.
  • a mixture comprises 20-70% by volume of nitrogen, 10-30% by volume of methane and 10-25% by volume of ethane and propane, respectively, also has good characteristics.
  • the boiling point of a mixture comprising 30% by volume of nitrogen, 30% by volume of methane and 20% by volume of ethane and propane, respectively, is about 80 K (at 1 bar).
  • the cooling capacity is better than that of nitrogen by a factor of 7 to 12.

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US12/020,934 2007-02-01 2008-01-28 Method for Cooling a Detector Abandoned US20080184711A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE200710004999 DE102007004999B4 (de) 2007-02-01 2007-02-01 Verfahren zur Kühlung eines Detektors
DE102007004999.6 2007-02-01
DE202007008674.1 2007-06-21
DE202007008674 2007-06-21

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070240408A1 (en) * 2006-04-14 2007-10-18 Ewa Environmental, Inc. Particle burner including a catalyst booster for exhaust systems
US20080271448A1 (en) * 2007-05-03 2008-11-06 Ewa Environmental, Inc. Particle burner disposed between an engine and a turbo charger
US20090071135A1 (en) * 2006-04-26 2009-03-19 Ewa Enviromental Inc. Corporation Reverse flow heat exchanger for exhaust systems
US20100095682A1 (en) * 2008-10-16 2010-04-22 Lincoln Evans-Beauchamp Removing Particulate Matter From Air
WO2010062446A1 (fr) * 2008-10-28 2010-06-03 Purify Solutions, Inc. Échelon de température de refroidissement et applications de celui-ci
US20100143090A1 (en) * 2008-12-04 2010-06-10 General Electric Company Cooling system and method for a turbomachine
US20110056228A1 (en) * 2009-09-10 2011-03-10 Jyh-Horng Chen Cooling apparatus for nuclear magnetic resonance imaging rf coil
US20170016772A1 (en) * 2014-03-06 2017-01-19 Société Francaise De Détecteurs Infrarouges - Sofradir Cooled detecting device
JP2019535018A (ja) * 2016-10-12 2019-12-05 レイセオン カンパニー 圧電性水晶マイクロバランス純度モニタ
US12090353B2 (en) 2020-03-20 2024-09-17 Kidde Technologies, Inc. Fire extinguishers, fire suppression systems, and methods of controlling flow of fire suppressant agents

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008052494A1 (de) * 2008-09-30 2010-04-08 Institut für Luft- und Kältetechnik gGmbH Joule-Thomson-Kühler

Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3320755A (en) * 1965-11-08 1967-05-23 Air Prod & Chem Cryogenic refrigeration system
GB1336892A (en) * 1971-05-17 1973-11-14 Nii Kriogennoi Elektroniki Refrigerant for a cryogenic throttling unit
US3818714A (en) * 1971-03-04 1974-06-25 Linde Ag Process for the liquefaction and subcooling of natural gas
EP0271989A1 (fr) * 1986-12-16 1988-06-22 Systron Donner Corporation Réfrigérant
US4781033A (en) * 1987-07-16 1988-11-01 Apd Cryogenics Heat exchanger for a fast cooldown cryostat
US4819451A (en) * 1986-12-13 1989-04-11 Hingst Uwe G Cryostatic device for cooling a detector
US5063747A (en) * 1990-06-28 1991-11-12 United States Of America As Represented By The United States National Aeronautics And Space Administration Multicomponent gas sorption Joule-Thomson refrigeration
US5084190A (en) * 1989-11-14 1992-01-28 E. I. Du Pont De Nemours And Company Fire extinguishing composition and process
US5150579A (en) * 1989-12-14 1992-09-29 Bodenseewerk Geratetechnik Gmbh Two stage cooler for cooling an object
US5382797A (en) * 1990-12-21 1995-01-17 Santa Barbara Research Center Fast cooldown cryostat for large infrared focal plane arrays
US5956958A (en) * 1995-10-12 1999-09-28 Cryogen, Inc. Gas mixture for cryogenic applications
US6042342A (en) * 1996-10-02 2000-03-28 T.D.I. --Thermo Dynamics Israel Ltd. Fluid displacement system
US6548619B2 (en) * 2000-08-15 2003-04-15 Eckhard Weidner Process for the production of polyurethane particles
US20050175653A1 (en) * 2004-01-29 2005-08-11 L'oreal Composition, process of making, uses thereof
US20060184102A1 (en) * 1999-03-12 2006-08-17 Trombley Frederick W Iii Container for agitating and injecting a multi-component medium
US20070000260A1 (en) * 2004-09-02 2007-01-04 Diehl Bgt Defence Gmbh & Co., Kg Cooling apparatus

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4135764C1 (fr) * 1991-10-30 1993-02-25 Bodenseewerk Geraetetechnik Gmbh, 7770 Ueberlingen, De

Patent Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3320755A (en) * 1965-11-08 1967-05-23 Air Prod & Chem Cryogenic refrigeration system
US3818714A (en) * 1971-03-04 1974-06-25 Linde Ag Process for the liquefaction and subcooling of natural gas
GB1336892A (en) * 1971-05-17 1973-11-14 Nii Kriogennoi Elektroniki Refrigerant for a cryogenic throttling unit
US4819451A (en) * 1986-12-13 1989-04-11 Hingst Uwe G Cryostatic device for cooling a detector
EP0271989A1 (fr) * 1986-12-16 1988-06-22 Systron Donner Corporation Réfrigérant
US4781033A (en) * 1987-07-16 1988-11-01 Apd Cryogenics Heat exchanger for a fast cooldown cryostat
US5084190A (en) * 1989-11-14 1992-01-28 E. I. Du Pont De Nemours And Company Fire extinguishing composition and process
US5150579A (en) * 1989-12-14 1992-09-29 Bodenseewerk Geratetechnik Gmbh Two stage cooler for cooling an object
US5063747A (en) * 1990-06-28 1991-11-12 United States Of America As Represented By The United States National Aeronautics And Space Administration Multicomponent gas sorption Joule-Thomson refrigeration
US5382797A (en) * 1990-12-21 1995-01-17 Santa Barbara Research Center Fast cooldown cryostat for large infrared focal plane arrays
US5956958A (en) * 1995-10-12 1999-09-28 Cryogen, Inc. Gas mixture for cryogenic applications
US6042342A (en) * 1996-10-02 2000-03-28 T.D.I. --Thermo Dynamics Israel Ltd. Fluid displacement system
US20060184102A1 (en) * 1999-03-12 2006-08-17 Trombley Frederick W Iii Container for agitating and injecting a multi-component medium
US6548619B2 (en) * 2000-08-15 2003-04-15 Eckhard Weidner Process for the production of polyurethane particles
US20050175653A1 (en) * 2004-01-29 2005-08-11 L'oreal Composition, process of making, uses thereof
US20070000260A1 (en) * 2004-09-02 2007-01-04 Diehl Bgt Defence Gmbh & Co., Kg Cooling apparatus

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Steven W. Rick and A.D.J. Haymet, Freeing of Mixtures, March 1, 1990, University of Utah, 5212-5220 *
Uwe Hingst*, Fast Cool-down Dual Gas Spray-Cooler For Pivoted IR-Detectors, 2003, Vol. 5074 *

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070240408A1 (en) * 2006-04-14 2007-10-18 Ewa Environmental, Inc. Particle burner including a catalyst booster for exhaust systems
US20090071135A1 (en) * 2006-04-26 2009-03-19 Ewa Enviromental Inc. Corporation Reverse flow heat exchanger for exhaust systems
US20080271448A1 (en) * 2007-05-03 2008-11-06 Ewa Environmental, Inc. Particle burner disposed between an engine and a turbo charger
US20100095682A1 (en) * 2008-10-16 2010-04-22 Lincoln Evans-Beauchamp Removing Particulate Matter From Air
WO2010062446A1 (fr) * 2008-10-28 2010-06-03 Purify Solutions, Inc. Échelon de température de refroidissement et applications de celui-ci
US20100143090A1 (en) * 2008-12-04 2010-06-10 General Electric Company Cooling system and method for a turbomachine
US20110056228A1 (en) * 2009-09-10 2011-03-10 Jyh-Horng Chen Cooling apparatus for nuclear magnetic resonance imaging rf coil
US20170016772A1 (en) * 2014-03-06 2017-01-19 Société Francaise De Détecteurs Infrarouges - Sofradir Cooled detecting device
US10161800B2 (en) * 2014-03-06 2018-12-25 Societe Francaise de Detecteurs Infrarouges—Sofradir Cooled detecting device
JP2019535018A (ja) * 2016-10-12 2019-12-05 レイセオン カンパニー 圧電性水晶マイクロバランス純度モニタ
US12090353B2 (en) 2020-03-20 2024-09-17 Kidde Technologies, Inc. Fire extinguishers, fire suppression systems, and methods of controlling flow of fire suppressant agents

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