Abstract: A magnetic substance represented by the following general formula (I):AMz (I)where A is at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb, M is at least one metal selected from the group consisting of Ni, Co, and Cu, and z is 0.001 to 9.0. This magnetic substance has its maximal of specific heat, due to magnetocaloric effect, at extremely low temperatures, the maximal value of specific heat being great. It also has a great lattice specific heat. A regenerator filled with the magnetic substance exhibits an excellent heat regeneration efficiency at extremely low temperature.

Abstract: An orifice pulse tube refrigerator (PTR) having a pulse tube and a reservoir with a compliance value C is provided with a variable acoustic impedance connecting the pulse tube and the reservoir. The variable acoustic impedance includes two or more variable impedances, which may be an inertance and valves forming variable resistive members, wherein the resulting acoustic impedance has a phase angle that is variable for improved cooling efficiency. The inertance may also be variable to further provide for varying the phase angle. In another improvement, an acoustic transmission line connects the pulse tube and a driver unit for recovering power from the pulse tube for return to the driver to further increase the PTR operating efficiency.

Abstract: A cold accumulating material for extremely low temperature cold 1 is formed by filling pores 3 of a porous carrier 2 with magnetic particles 4 containing a rare earth element. The porous carrier 2 is desired to be formed of a sheet-shaped porous metal. A refrigerator according to this invention contains a cold reserving unit 5 filled with the aforementioned cold accumulating material for extremely low temperature cold 1. The above described structure is capable of exerting a sufficient refrigerating capacity with a small pressure loss of refrigerant (operating medium) and providing a cold accumulating material for extremely low temperature cold easy to process to a shape reducing the pressure loss and a refrigerator using the same.

Abstract: The electricity generating engine has modest efficiency, but may be attrave in remote applications where high-reliability or low cost or low environmental noise or solar powering is important. The generator is likely to be most attractive in capacities of a few kW to below 100 W where a tiny engine would be impractical using other technologies.

Abstract: The apparatus for the expansion of fluid in the gaseous or liquid state or in double phase is characterized in that it has an expansion compartment comprising:a first spiral (72),a second spiral (70) located within said first spiral,means (52, 63) to permit a circular translation movement without self-rotation of the second spiral within the first spiral during the expansion of a fluid.

Abstract: In a cooling apparatus for a high-frequency receiver having an input circuit which carries signals that are not yet sufficiently amplified, the input circuit is thermally connected to a miniature cooler and is thermally insulated, including a cold output of the miniature cooler, from the environment. It is particularly favorable if the miniature cooler has no moving parts on the cooling end. The miniature receiver is preferably configured as a pulse tube cooler.

Abstract: In a second displacer (33), a final layer (33c) measuring 10 K or lower in temperature is filled with spherical particles (34) of HoCu.sub.2 which exhibit a specific heat greater than that of Er.sub.3 Ni. An intermediate layer (33d) of 10 K to 15 K is filled with spherical particles (35) of Er.sub.3 Ni, Er.sub.3 Co or Nd. Further, an initial layer (33e) of 15 K or higher is filled with spherical particles (36) of Pb. By the use of such regenerative materials that exhibit the highest specific heats respectively for the individual temperature regions of 10 K or lower, 10-15 K, and 15 K or higher, the second displacer (33) exhibits an enhanced refrigerating capacity, as compared with the case of filling the final layer with the spherical particles of Er.sub.3 Ni as conventionally done. This further makes it possible to construct the second displacer (33) in a compact size and in a reduced weight.

Abstract: A pulse tube refrigerator which can generate cryogenic temperatures of below 10 K includes first and second refrigeration stages. Each stage includes a pulse tube and an associated regenerator provided at the low temperature side of the pulse tube. A pressure fluctuation generator having a compressor and a first to a fourth valve is provided at the high temperature side of each regenerator. The high temperature sides of each pulse tube are connected by a continuous channel while the high temperature side of each pulse tube and the high temperature side of each regenerator are connected by a by-pass channel. A magnetic material having a rare-earth element and a transition metal is used as a regenerative material for the regenerator. When pressure fluctuation is generated in each pulse tube at the phase difference angle of 180.degree.

Abstract: An electrically cooled detecting system comprises: two or more heat regenerative refrigerators each having a cylinder with a cooling head at its one end; a holder for supporting the two or more heat regenerative refrigerators to dispose the one ends of the cylinders along a certain plane and the other ends of the cylinders on one side of the certain plane; a connector for thermally and rigidly connecting the cooling heads; and a detector being thermally connected to the connector. This system is not necessary to use liquid nitrogen. This system is compact and has a high energy resolution.

Abstract: A pulse tube refrigerator is equipped with a constant-diameter inertance tube (41) or a stepped or tapered intertance tube (48) which is coiled in a reservoir (20) to protect it from damage from external impacts and from structural failure due to differences between external and internal pressures. A tapered inertance tube (48) improves thermodynamic performance of the pulse tube refrigerator by improving heat transfer at the warm end of pulse tube (10).

Abstract: Fluidic devices, including constant-rotation double diodes and constant-rotation double vortex tubes, are disclosed with which to construct pulse tube refrigerators having diode loops, constant-rotation double diodes, constant-rotation double vortex tubes, and asymmetrical diode stacks. Present orifice pulse tube refrigerators use an orifice connected at the warm end of the pulse tube to a reservoir. The orifice and reservoir serve to control flows at the warm end of the pulse tube so that they are not in phase with flows at the cold end. Present heat exchangers at the warm end suffer inefficiencies due to heat-regenerative effects caused by return flows through the orifice. The fluidic devices disclosed herein create dynamic replacement orifices for pulse tube refrigerators that also serve as efficient heat exchangers and supercoolers with minimal regenerative characteristics.

Abstract: A superconducting magnet system, such as an NMR apparatus, is outfitted with a compact-size refrigerator that prevents mechanical vibrations produced by the refrigerator from being transmitted to the superconducting magnet system. The refrigerator is in the form of a pulse tube refrigerator having a cold head and a pressure oscillation generating source. The cold head of the pulse tube refrigerator is connected directly to a vacuum insulation vessel of the superconducting magnet system. Cold generated from the cold head cools a cooling device, for example, a liquid helium tank for cooling the superconducting coil, or a heat penetration reducing device, for example, a liquid nitrogen tank, for reducing heat penetration from outside.

Abstract: Occurrence of leakage of refrigerant around a seal member in cryogenic state is suppressed. The seal member 32 is formed from unsaturated polyester-PTFE with an unsaturated polyester mixing ratio of 20% to 35%. A plurality of slits 36 extended axially and penetrating through radially are provided in an end portion 35 of an outer circumferential wall 32a. Thus, by a synergistic effect of the use of a material small in the heat shrinkage factor and the reduction of radial shrinkage of the whole outer circumferential wall 32a attributable to the aforementioned configuration, the sealing properties in the cryogenic state are enhanced so that the occurrence of leakage of refrigerant is suppressed to the utmost, thereby preventing deterioration in the refrigeratability.

Abstract: Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

Abstract: This invention for the production of high amplitude acoustic standing wav which can be used for thermoacoustic heat transport purposes, describes the use of a rigid barrier in place of a piston, thereby allowing the suspension of the resonator to be external to the pressurized resonator and allowing an independent choice of motor mechanism, including the use of rotary motors instead of linear motors, while incidently providing a mechanism for circulating external heat transport fluids without requiring additional pumps or heat pipes.

Abstract: A microminiature Stirling cycle engine or cooler is formed utilizing semiconductor, planar processing techniques. Such a Stirling cycle thermomechanical transducer has silicon end plates and an intermediate regenerator. The end plates are formed with diaphragms and backspaces, one end plate forming the expansion end and the opposite end plate forming the compression end, with the regenerator bonded in between. A control circuit apparatus is linked to the diaphragms for controlling the amplitude, phase and frequency of their deflections. The control circuit apparatus is adapted to operate the transducer above 500 Hz and the passages and the workspace, including those within the regenerator, expansion space and compression space, are sufficiently narrow to provide a characteristic Wolmersley number, which is characteristic of the irreversibilities generated by the oscillating flow of the working fluid in the workspace, below substantially 5 at the operating frequency above 500 Hz.

Abstract: This invention provides a mechanical support for a two-pill Adiabatic Demagnetization Refrigerator (ADR). The support utilizes a suspension of the two pills from one side of the magnet bore only. In the two pill ADR, the thermal ground is at 4K, a guard pill positioned in the front of the bore cools to 1K and a base pill positioned in the back of the bore cools to 50-100 mk. A connector rod of the base pill traverses the guard pill, and connector rods to both the guard pill and base pill exit through the front aperture. A preferred embodiment of the two-pill support for the front loaded magnet bore utilizes planar support modules comprising three members connected by Kevlar strings. Each member is thermally connected either to one of the pills or to thermal ground. The ground member, the guard member and the base member of the support module are strung with Kevlar threads, such that the base member is suspended only from the guard member, and the guard member only from the ground member.

Abstract: A Stirling refrigerating system comprising a freezing chamber, a Stirling refrigerator, and a heat carrying means including a pipe arrangement thermally connected to a cooling portion of the Stirling refrigerator so as to carry low temperature heat of the cooling portion to the freezing chamber by means of a refrigerant, wherein when the Stirling refrigerator is driven, the refrigerant circulates in the freezing chamber and the cooling portion through the pipe arrangement. Thus, it is possible to obtain a Stirling refrigerating system in which not only it can cope with the current flon regulation but also it can use ethyl alcohol or the like as a refrigerant other than HCFC or HFC which may be subjected to legal regulation in the future, and it can increase the refrigerating capacity and improve the coefficient of performance in comparison with the existing system.

Abstract: A vibration-actuated pump is connected to a stirling-cycle refrigerator for absorbing the vibration generated when the stirling refrigerator is operated. The absorbed vibration is converted into a driving power for operating a pump to circulate a heat-transferring medium of a cooling circuit and/or a freezing circuit.

Abstract: A method of running a pulse tube refrigerator which has a regenerator and a pulse tube each defining a high temperature end and a low temperature end, the low temperature ends of the regenerator and the pulse tube being communicated with each other, and the high temperature end of the regenerator being connected to a gas compressor. A cold area is formed at the low temperature ends by periodically supplying working gas from the high temperature end of the regenerator to the regenerator and recovering the working gas from the regenerator. The temperature of the low temperature ends is raised by steadily, pulsatively or intermittently flowing gas in one direction through a communicating area between the low temperature ends of the regenerator and the pulse tube.

Abstract: Improved flexures and flexure assemblies are taught for use in thermal regenerative machines. In one aspect, the flexure is a flat spring formed from a flat metal sheet having kerfs forming axially movable arms across them, and at least one aperture communicating with and extending from an end portion of the kerf. One variation includes a flexure bearing assembly having such a flexure. In accordance with another aspect, a thermodynamic machine has a housing carried stator and a piston and linear moving element carried by a flexure bearing assembly. In accordance with yet another aspect, a piston and displacer assembly are configured to be movably supported together within a chamber in a housing of a thermal regenerative machine via a flexure assembly.

Abstract: A recondensing zero boiloff superconducting magnet assembly utilizing a cryocooler with a compressible indium gasket positioned between the cryocooler and the recondenser and with the gasket containing a plurality of spaced parallel grid wires with interconnecting web segments of a lesser thickness interconnecting the mid sections of ends of adjacent wires to facilitate compression of the gasket to control improved thermal conductivity while minimizing the pressure and forces on the assembly.

Abstract: A refrigerator for cryogenic pumps, cryostats and the like, includes a housing having a cylindrical working volume inside the housing and a displacement element capable of moving in a reciprocal manner within the working volume. The displacement element is driven by a gas drive. To reduce vibrations, the displacement element is forcibly guided.

Abstract: A displacer assembly for a Stirling cycle system includes a displacer and a synchronous linear electric motor linked so as to drive the displacer. The electric motor features at least one stator assembly having first and second soft-magnetic pole pieces defining therebetween a gap. The width of the gap is oriented perpendicular to an axis of movement of the motor, and the stator assembly is constructed so as to generate a magnetic field aligned primarily parallel to the width of the gap. The motor also includes at least one compound permanent magnet system located within the gap. The compound permanent magnet system has a first section magnetized in a first direction parallel to the width of the gap and a second section axially displaced from the first section magnetized in a direction opposite to the first direction. The result of this structure is that the electric motor operates as a magnetic spring which, when no power is supplied to the motor, returns the displacer to a predefined rest position.

Abstract: A pulse tube refrigeration system includes a pressure wave generator generating continuous pressure wave of a working fluid: a regenerator having a low temperature end and a high temperature end connected to the pressure wave generator; a cold head connected at one end thereof to the low temperature end of the regenerator and producing a very low temperature; a pulse tube having a high temperature end and a low temperature end connected to the other end of the cold head; and a phase shifter adjusting a phase difference between a pressure oscillation and a displacement of the working fluid and transmitting an expansion work of the working fluid to the high temperature end of the regenerator in mechanical mode which is performed at the high temperature end of the pulse tube.

Abstract: This invention describes a new geometry for a heat driven thermoacoustic me mover (i.e. acoustic motor) and its application to a thermoacoustic refrigerator and to an electricity generator. The heat driven acoustic refrigerator has no moving parts, and is thus extremely reliable, simple, and cheap to manufacture. Unlike previous heat driven acoustic cooling engines, it has good efficiency and compactness and is easy to start, avoiding destructively high temperatures upon start-up. The cooling engine is saleable over an extremely wide range of cooling capacities from integrated circuit and sensor cooling to building air-conditioning. The electricity generating engine has modest efficiency, but may be attractive in remote applications where high-reliability or low cost or low environmental noise or solar powering is important. The generator is likely to be most attractive in capacities of a few kW to below 100 W where a tiny engine would be impractical using other technologies.

Abstract: A compressor including a chamber having a standing acoustical wave therein, the wave having at least first and second velocity nodes, the first velocity node having a smaller cross-sectional area than the second velocity node, a high pressure inlet adapted to receive relatively high pressure gas, an inlet mechanism operably connected to the high pressure inlet and to the chamber, the inlet mechanism being associated with the first velocity node and adapted to supply pulses of the relatively high pressure gas to the chamber at a predetermined rate, at least one outlet valve associated with the second velocity node of the chamber and adapted to allow gas at a relatively low pressure to pass therethrough, and a low pressure inlet operably connected to the chamber.

Abstract: A passive balance system for counterbalancing vibrations of a machine is taught. The passive balance system includes a support member adapted to be fixedly carried by the machine and a flexure assembly carried by the support member. The flexure assembly is in the form of at least one flat spring including connections along a central portion. The central portion is fixedly mounted to the support member, and an outer peripheral portion of the flat spring provides at least in part a movable counterbalance mass. The flexure assembly presents the counterbalance mass for movement in substantial alignment with a desired rectilinear component of vibration of the machine to counterbalance vibrations emanating therefrom. A vibration balanced machine having the passive balance system is also disclosed.

Abstract: The compact oxygen production system of the present invention provides an oxygen concentrator and a cryocooling device for liquefying the concentrated oxygen gas to provide liquid oxygen. The compact size of the system permits the system to be employed in home applications, especially for home oxygen patients.

Abstract: This invention relates to a process for Heating, Ventilating and Air Conditioning (HVAC) applications. In particular, this invention relates to a method for supplying oxygen concentrated air to an indoor air environment, which is termed as High Level Oxygen Air Conditioning (HLOAC): The High Level Oxygen Air Conditioning (HLOAC) primarily comprises three steps: (1). Introducing air stream to an oxygen and nitrogen separation device; (2). Separating nitrogen and oxygen in air to obtain a concentrated oxygen stream; (3). Introducing said concentrated oxygen stream into the indoor environment.

Abstract: A dual stage active magnetic regenerator refrigerator as well as method using the Joule-Brayton thermodynamic cycle includes a high temperature stage refrigerant comprising DyAl.sub.2 or (Dy.sub.1-x Er.sub.x)Al.sub.2 where x is selected to be greater than 0 and less than about 0.3 in combination with a low temperature stage comprising (Dy.sub.1-x Er.sub.x)Al.sub.2 where x is selected to be greater than about 0.5 and less than 1 to provide significantly improved refrigeration efficiency in the liquefaction of gaseous hydrogen.

Abstract: This invention concerns a method of operating a cryogenic cooling device (1) with a cylinder (4, 5) in which a piston (6, 7) reciprocates and with a gas drive (8, 9) which produces the motion of the piston. In order to reduce the vibrations which occur during operation, the invention proposes that the gas drive (8, 9) is controlled in such a way that the piston (6, 7) is only accelerated for part of the stroke.

Abstract: A Stirling-cycle refrigerator has a three-pump configuration and pumping sequence, in which one pump serves as a compressor, one pump serves as an expander, and one pump serves as a displacer. The pumps are ferroelectrically actuated diaphragm pumps which are coordinated by synchronizing the ferroelectric-actuator voltages in such a way that the net effect of the displacer is to reduce the deleterious effect of dead space; that is, to circulate a greater fraction of the working fluid through the heat exchangers than would be possible by use of the compressor and expander alone. In addition, the displacer can be controlled separately to make the flow of working fluid in the heat exchangers turbulent (to increase the rate of transfer of heat at the cost of greater resistance to flow) or laminar (to decrease the resistance to flow at the cost of a lower heat-transfer rate).

Abstract: The resonance frequency of a gas-filled acoustic resonator (12) is stabilized against changes in frequency due to changes in the temperature of the gas and resonator (12) by placing a gas mixture and an adsorbent (16) within the resonator (12). If the temperature dependence of the adsorbency is different for the different species comprising the gas mixture, then it is shown that the proper amount of adsorbent (16) can maintain the acoustic resonant frequency of the gas mixture within resonator (12) very nearly equal to a constant frequency.

Abstract: A pulse tube refrigerator according to the present invention is capable of performing cryogenic operation sufficiently. The cryostat includes regenerators and pulse tubes. Each regenerator has a cold stage at an upper end thereof. Each pulse tube has a low-temperature end portion at a lower end thereof and a high-temperature end portion thereof, the low-temperature end portion being located lower than the cold stage. The cold stage and the low-temperature end portion are connected to each other through a line whose cubic volume is substantially negligible in comparison with that of the pulse tube. Since the pulse tube has working gas of relatively high density in an upper portion thereof and working gas of relatively low density in a lower portion thereof, there is no convection of working gas induced by the gravity. Thus, the cryostat performs cryogenic operation sufficiently without being adversely affected.

Abstract: An adaptive feedforward vibration control system reduces vibrations at fundamental and harmonic frequencies of matched reciprocating pistons, such as back-to-back compressor pistons in Stirling cycle cryocooler, by driving the pistons with correction signals. The system is also applicable to reducing the vibrations generated by a pair of opposite expander and balancer pistons in a cryocooler. The correction signals are computed iteratively to increase their accuracy, and need only be updated relatively infrequently to adjust the pistons' motions, thereby enabling the use of a relatively slow microprocessor.

Abstract: This invention provides a low friction linear clearance seal for use in closed cycle cryogenic coolers. The clearance seal comprises a cylinder, a piston mounted within the cylinder for reciprocating movement and a self lubricating polymer liner bonded to the piston which forms an effective seal around the piston. The clearance seal improves the sealing capability between the piston and the cylinder and reduces heat generated by the motion of the piston along the cylinder wall. The clearance seal also improves the performance and reliability of the cryogenic cooler.

Abstract: A resonantly coupled .alpha.-Stirling cooler has hot and cold variable-volume chambers, a regenerator, and a driver for maintaining reciprocating gas displacement between the chambers. Only the hot side of the cooler is driven; the cold side responds passively by resonant coupling. The phase difference between volume oscillations in the hot and cold variable-volume chambers are altered by adjusting the driving frequency.

Abstract: A electroacoustic cooling engine comprising a resonator pressure vessel for containing a compressible fluid, a double acting flexural disk centrally located in the resonant pressure vessel, an electromagnetic driver supported outside the vessel for driving the disk from outside the vessel, a thermodynamic element on each side of the disk and a pair of heat exchangers on opposite sides of the thermodynamic element. The electromagnetic driver linearly actuates the disk to cyclically drive a standing acoustic wave on both sides of the disk through each thermodynamic element and heat exchanger pair to generate a desired thermal response in a working fluid flowing through each heat exchanger.

Abstract: A closed hollow filter canister having gas-impermeable end walls (94, 96) and a gas-permeable side wall (100). Gas contaminated with liquid is sprayed under pressure through line (90) and flow-restricting orifice (80) into the interior space of the canister where the contaminants become atomized and are retained by the side wall (100). Gas free of liquid contaminants passes into the atmosphere. In a preferred embodiment the gas is air contaminated with water, and the wall (100) is of cellulosic material which becomes wetted with water which gradually volatilizes. The filter canister may be used to treat streams (90a, 90b) from a gas compressor (50) and an associated reservoir tank (125).

Abstract: An improved apparatus for controlling a refrigerator equipped with a linear compressor which is capable of achieving an optimum driving efficiency of the system irrespective of an operational condition of a refrigerator by providing the refrigerator with a linear compressor. The apparatus includes an operation ratio computation unit for computing an operation ratio of a compressor, a cooling capacity computation unit for computing a cooling capacity based on a stroke distance of a piston of the compressor, and a controller for maintaining a constant operation ratio by controlling the piston stroke distance in accordance with the operation ratio and the cooling capacity.

Abstract: An electrical component cooling system is described which achieves low cooling temperatures for densely packaged electrical components using environmentally friendly working fluids. The cooling system uses a remotely located pressure wave generator to provide working fluid pulses to a plurality of regenerators. The mass flow and pressure relationships effecting cooling for the regenerator is controlled by tuning the pulse tube, orifice, and working fluid reservoir characteristics.

Abstract: The invention relates to method and an arrangement for utilizing the heat comprised i the exhaust gas of the combustion chamber of a heating and refrigerating engine working on the basis of a regenerative cyclic gas process by preheating the combustion air supplied to the combustion chamber, with the process gas, which is displaced from the hot working volume or supplied to this working volume, flowing through a regenerator arranged inside of a pressure-proof housing in the region of the hot piston. In order to achieve an effective utilization of the exhaust gas heat without additional apparatus complexity and without insulation of the engine in the region of the warm regenerator while maintaining the temperature profile necessary for the operation of the regenerator, the combustion air to the cooling of the pressure vessel wall surrounding the lower section of the regenerator is used, which cooling corresponds to the lower section of the temperature profile of the regenerator.

Abstract: An orifice pulse tube refrigerator is provided with a flow separation member in the pulse tube so as to prevent mixing of hot and cold gases from opposite end of the pulse tube, thus reducing losses due to mixing and improving efficiency. The flow separation member may take the form of a cylindrical slug of low-friction material mounted in the pulse tube for sliding movement in response to instantaneous variation in working gas pressure.

Abstract: A cryogenic refrigerator includes a displacer and a cylinder therein for generating a very low temperature. And, a sealing ring is provided in an inserted condition within a ring shaped groove which is formed at an outer peripheral portion of the displacer, the sealing ring having resilience for extending itself outward so that a sealing member on an outer diameter thereof is enlarged and that an outer portion of the sealing ring is slidably contacted to an inner face of the cylinder, and the sealing ring being made of non-magnetic alloy, thereby a magnetic noise and disturbance of an outer magnetic field due to the cryogenic refrigerator are greatly decreased.

Abstract: The device permits the precise guiding and centering of machine elements, for example of a piston rod (7) or a piston (3,4) in a cylinder (5,6). Therein two guides (11,12) are disposed at approximately right angles to the longitudinal axis (2) of the piston rod (7) and at a distance from each other. Each guide (11,12) comprises several spring elements (15) which extend radially from the axis (2). The spring elements (15) comprise long main spring parts (16) and short auxiliary spring (17). The spring parts (16,17) are rigidly connected one with the other via connection parts (18). The guides (11,12) have with respect to the axis (2) high transverse rigidity and permit precisely guided oscillating motions of the machine elements (3,4,5,6,7) along the longitudinal axis (2). These guides (11,12) permit for example the contact-free relative motions between piston (3,4) and cylinder (5,6) and have a high service life and operational reliability.

Abstract: A method for regulating the cooldown of multiple cryogenic refrigerators supplied with compressed refrigerant from a common compressor includes the following steps. The cooldown of the refrigerators is monitored. The cooldown of at least one refrigerator is then governed to regulate the gas flow distributed from the compressor to each of the refrigerators to enhance the cooldown of an individual refrigerator. Governing a refrigerator to achieve the objectives of this method can be achieved by various processes. These processes include supplying heat to the refrigerator, slowing the speed of the displacer in the refrigerator, halting the motion of the displacer, and profiling the speed of the displacer as a function of the first and second-stage temperatures.

Abstract: A method for detecting the absence of a pressure differential across a cryogenic refrigerator includes the following steps. At least one measurement of load in the refrigerator is taken during both a warmstroke and a coldstroke of a refrigeration cycle. These measurements are then compared to determine whether the differential load across the cryogenic refrigerator has been lost. A system for performing this method includes a compressor that circulates compressed gas through a compressed gas line routed through a cryogenic refrigerator. Within the refrigerator, a displacer is driven through a refrigeration cycle by a motor. A means for measuring the load on the motor is provided, and an electronic module monitors the load measurements to detect a loss of differential pressure across the refrigerator by comparing the load on the motor during the warmstroke to the load on the motor during the coldstroke.

Abstract: A cooler structure of stirling engine is designed to make it easier for the production of the cooler by using brazing soldering techniques, and which in turn reduces the loss of the heat being transmitted to the cooling water and the displacer seal. The invention includes a sealing filler metal having the same depth formed around the circumference of each surface of the upper and lower plates which seals the radiator tubes to be fixed and sustained by the upper and lower plates. An adiabatic part is formed between the upper plate having a projection maintaining a predetermined length toward the inner low part. The internal cylinder prevents the passing of the heat from the internal cylinder to the radiator tube.

Abstract: A miniature mixed gas refrigeration system and method of operation are disclosed. An optimum gas mixture is formulated from a group of component fluids, according to calculated thermodynamic properties of a group of candidate fluid mixtures. The gas mixture is pressurized by a compressor to a pressure less than 420 psia, for safety reasons. The compressed gas mixture is passed through a primary heat exchanger, and then through a primary-to-secondary heat exchanger, to precool the gas mixture. The secondary side of the primary/secondary heat exchanger is cooled by a secondary Joule-Thomson refrigeration system. Properly sized flow restrictions in the primary side of the primary/secondary heat exchanger can solidify and trap liquid contaminants that may be in the gas mixture. The gas mixture exiting the primary outlet of the primary/secondary heat exchanger passes to a primary Joule-Thomson expansion element where the high pressure gas is expanded isenthalpically to a lower temperature at least as low as 183K.