US20030226364A1 - Method and apparatus for fine tuning an orifice pulse tube refrigerator - Google Patents
Method and apparatus for fine tuning an orifice pulse tube refrigerator Download PDFInfo
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- US20030226364A1 US20030226364A1 US10/163,781 US16378102A US2003226364A1 US 20030226364 A1 US20030226364 A1 US 20030226364A1 US 16378102 A US16378102 A US 16378102A US 2003226364 A1 US2003226364 A1 US 2003226364A1
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- 238000000034 method Methods 0.000 title claims description 9
- 230000001105 regulatory effect Effects 0.000 claims abstract description 14
- 230000001276 controlling effect Effects 0.000 claims abstract description 8
- 230000002123 temporal effect Effects 0.000 claims abstract description 8
- 239000012530 fluid Substances 0.000 claims description 13
- 238000001816 cooling Methods 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims 4
- 239000007789 gas Substances 0.000 description 17
- 238000005057 refrigeration Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 239000012080 ambient air Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000010363 phase shift Effects 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000004078 cryogenic material Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000003534 oscillatory effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000001932 seasonal effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
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Classifications
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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
- F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
- F25B9/145—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle pulse-tube cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G2243/00—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes
- F02G2243/30—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders
- F02G2243/50—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders having resonance tubes
- F02G2243/54—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders having resonance tubes thermo-acoustic
-
- 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
- F25B2309/00—Gas cycle refrigeration machines
- F25B2309/14—Compression machines, plants or systems characterised by the cycle used
- F25B2309/1407—Pulse-tube cycles with pulse tube having in-line geometrical arrangements
-
- 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
- F25B2309/00—Gas cycle refrigeration machines
- F25B2309/14—Compression machines, plants or systems characterised by the cycle used
- F25B2309/1411—Pulse-tube cycles characterised by control details, e.g. tuning, phase shifting or general control
-
- 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
- F25B2309/00—Gas cycle refrigeration machines
- F25B2309/14—Compression machines, plants or systems characterised by the cycle used
- F25B2309/1423—Pulse tubes with basic schematic including an inertance tube
Definitions
- the present invention relates generally to orifice pulse tube refrigerators, and, more particularly, to orifice pulse tube refrigerators with reduced Rayleigh streaming in the pulse tube.
- Orifice pulse tube refrigeration is the most rapidly developing field of cryogenic refrigeration today.
- the high efficiency of a Stirling-based thermodynamic cycle, the lack of moving parts at cryogenic temperature, and the lack of small, easily plugged orifices at cryogenic temperature combine to make this new technology inexpensive and reliable.
- orifice pulse tube refrigerators can be driven by thermoacoustic heat engines, creating for the first time cryogenic refrigeration with no moving parts. Background information about orifice pulse tube refrigerators is given, for example, by R. Radebaugh, “A review of pulse tube refrigeration,” pages 1191-1205 in Adv. Cryogenic Eng., Volume 35 (1990), and in R.
- FIG. 1A A prior art orifice pulse tube refrigerator is shown schematically in FIG. 1A.
- One of the key parameters in an operational orifice pulse tube refrigerator is the temporal phase difference between oscillating pressure and oscillating velocity.
- the reference convention used herein is that x is the distance from the driver along the axis of the refrigerator, that positive velocity is velocity in the positive x direction, and that ⁇ is the temporal phase angle by which oscillating pressure leads oscillating velocity.
- This temporal phase ⁇ is also called the phase of the complex acoustic impedance Z. It is well known that ⁇ is a function of x, due for example, to the compressibility of the gas in various portions of the refrigerator.
- FIG. 1B illustrates, for example, the viscous pressure drop across regenerator 12 , which manifests itself as the difference between the pressure phasor P 1,driver at driver 10 and the pressure phasor P 1,pulse tube in pulse tube 18 .
- the difference between the volume flow rate phasor U 1,ambient heat exchanger at ambient heat exchanger 28 and the volume flow rate phasor U 1,cold at cold heat exchanger 26 is due to the compressibility of the gas in pulse tube 18 .
- FIG. 1B illustrates, for example, the viscous pressure drop across regenerator 12 , which manifests itself as the difference between the pressure phasor P 1,driver at driver 10 and the pressure phasor P 1,pulse tube in pulse tube 18 .
- the difference between the volume flow rate phasor U 1,ambient heat exchanger at ambient heat exchanger 28 and the volume flow rate phasor U 1,cold at cold heat exchanger 26 is due to the compressibility of the gas in pulse tube 18 .
- P 1,ambient heat exchanger can be assumed nearly identical to P 1,pulse tube , so ⁇ ambient heat exchanger is the angle by which P 1,pulse tube leads U 1,ambient heat exchanger , which is approximately 50 degrees in FIG. 1B. This is a typical value for an orifice pulse tube refrigerator with an inertial impedance (“inertance”).
- variable acoustic impedance network as shown atop pulse tube 18 in FIG. 1A, is described, comprising an inertance tube 14 , a compliance volume 22 , and two adjustable flow resistance valves 16 , 24 .
- FIG. 2 which is a reproduction of FIG. 7 from the '643 patent, shows the broad range of ⁇ ambient heat exchanger accessible by this method.
- the points on FIG. 2 show some typical values of acoustic impedance Z at the top of the pulse tube, experimentally accessed by adjusting the two valves 16 , 24 ; all points between these points are also accessible. Absent viscous effects in inertance 14 , all values of Z between the two horizontal dashed lines would be accessible, and the experimental reality is not far from that ideal.
- the values of ⁇ represented by these points range from about zero to 80 degrees (the angle between the horizontal axis and a line from the origin to a given point).
- FIG. 2 The three large circles on FIG. 2 are contours of constant power dissipation in the acoustic impedance network 14 , 16 , 22 , 24 , and, hence, of constant gross cooling power at cold heat exchanger 26 .
- an operating point for the orifice pulse tube refrigerator is uniquely defined by, and is often chosen by, selecting a gross cooling power, i.e., at which circle one wants to operate, and a value of ⁇ .
- the actual net refrigerating power is the gross cooling power minus the sum of heat leaks to cold heat exchanger 26 .
- Imperfect operation of regenerator 12 and imperfect operation of pulse tube 18 are two sources of potentially large heat leaks, but proper design can minimize these. Efficient refrigeration also requires little viscous dissipation in regenerator 12 .
- regenerator efficiency is not too strong, and a regenerator with ⁇ (x) shifted by 10 or even 20 degrees from the optimal values may not have a noticeable loss in efficiency with respect to either viscous dissipation or heat leak.
- the temporal phase ⁇ also plays an important role in the efficiency of the pulse tube of the orifice pulse tube refrigerator.
- Pulse tubes are susceptible to an internal, toroidal steady convection, called Rayleigh streaming, that is superimposed upon the desired oscillatory motion.
- Rayleigh streaming reduces the efficiency of orifice pulse tube refrigerators because the streaming convects heat from ambient heat exchanger 28 atop pulse tube 18 to cold heat-exchanger 26 at the bottom of pulse tube 18 , thereby reducing the cooling power of the orifice pulse tube refrigerator.
- Rayleigh streaming is caused by boundary-layer processes at the side walls of the pulse tube, which are controlled by various parameters including phase angle ⁇ , the taper angle of the pulse tube, and properties of the working gas, as described by J. R.
- the temporal phase ⁇ can be adjusted, as described in the '643 patent, but there is no need for such a large range of adjustability when nominally identical orifice pulse tube refrigerators are mass produced for nominally identical applications.
- an acoustic impedance network with geometrically fixed components would be much cheaper than the high-pressure bellows-sealed valves described in Swift et al., supra.
- expensive high-torque valve actuators may also be needed to adjust the resistances automatically.
- it is often necessary to provide fine-tuning adjustment of the acoustic impedance network because of the sensitivity of Rayleigh streaming to the conditions of operation.
- Even nominally identical orifice pulse tube refrigerators that are mass produced for nominally identical applications may suffer from minor unit-to-unit construction variations or from diurnal and seasonal variations in ambient temperature.
- the present invention includes an orifice pulse tube refrigerator having flow resistance, compliance, and inertance components connected to a pulse tube for establishing a phase relationship between oscillating pressure and oscillating velocity in the pulse tube.
- a temperature regulating system heats or cools a working gas in at least one of the flow resistance and inertance components.
- a temperature control system is connected to the temperature regulating system for controlling the temperature of the working gas in the at least one of the flow resistance and inertance components and maintains a control temperature that is indicative of a desired temporal phase relationship.
- FIGS. 1A and 1B schematically depict a prior art orifice pulse tube refrigerator having an inertance and a phasor diagram of the phase relationships in the refrigerator.
- FIG. 2 graphically depicts the broad range of impedance Z and phase ⁇ values atop the pulse tube that can be obtained by adjusting resistive valves in a typical acoustic impedance network.
- FIG. 3 graphically depicts the heat leak in one pulse tube as a function of phase ⁇ .
- FIG. 4 schematically depicts an orifice pulse tube refrigerator with an exemplary system for fine tuning the phase ⁇ according to the present invention.
- FIGS. 5A and 5B schematically depict orifice pulse tube refrigerators with two other systems for fine tuning the phase ⁇ according to the present invention.
- some or all of the elements of the acoustic impedance network atop pulse tube 18 can be enclosed with temperature control jackets 30 , 31 that, e.g., contain a flowing fluid 32 , whose flow rate can be controlled, e.g., by valves 34 , 36 .
- the fluid flow rate controls the temperature of those elements and provides fine control for the resulting phase angle ⁇ between oscillating pressure and oscillating flow rate.
- the basic pulse tube refrigerator elements having the same function as elements shown in FIG. 1A have like numbers.
- the inertial impedance of an inertance tube is equal to the product of the gas density times the cross sectional area divided by the length of the tube, and the gas density is proportional to the absolute temperature.
- the temperature of the working gas provides a significant control of inertance 42 , which contributes to the imaginary part of Z—the vertical axis in FIG. 2.
- the resistive impedance of a resistive valve, fixed orifice, flow impedance, or other flow resistance 38 depends on the viscosity of the gas, which, in turn, is typically proportional to the 0.7 power of the absolute temperature.
- the temperature of the working gas provides a significant control of the resistive impedance, which contributes to the real part of Z—the horizontal axis in FIG. 2.
- the compliance of compliance tank 44 is independent of temperature.
- the temperatures of the working gas in these components is determined by a balance among dissipation of acoustic power into heat within these components; thermoacoustic transport of heat through the working gas to or from these components, from or to adjacent components; and the temperatures of the solid surfaces of the components.
- the present invention provides for varying flow resistance and/or inertance of the acoustic impedance network by varying the temperature of the working gas in at least one of these components in an orifice pulse tube refrigerator.
- All orifice pulse tube refrigerators reject waste heat to ambient temperature, usually to a flowing stream of ambient water or ambient air. Either of these two fluids can be used in temperature control jackets 30 , 31 .
- the control of the flow rate of external temperature control fluid 32 by means of valves 34 , 36 is much less expensive than the control of a variable valve in the orifice pulse tube refrigerator acoustic impedance network because the external air or water is typically at or near ambient pressure, so operating torques are small and sealing challenges are minor.
- fluids leaking from an external system are readily replaced.
- flue gas could be used as the fluid 32 whose flow through jackets 30 , 31 is controlled, thereby providing variable warming of the resistive 38 and inertial 42 elements instead of the variable cooling provided by ambient air or water described in the previous paragraph.
- heaters 130 , 131 can be used in temperature control jackets 30 , 31 to control the temperatures of resistive 38 and inertial 42 components.
- Heaters 130 , 131 may be electric resistance heaters or combustion heaters.
- FIG. 5B Another alternative, shown in FIG. 5B, is to control valve 134 to adjust fluid flow 132 to thereby regulate the temperature of ambient heat exchanger 128 atop the pulse tube. This alternative relies on the thermoacoustic thermal connection in the working gas between ambient heat exchanger 128 and resistive 38 and inertial 42 components to control the temperatures of resistive 38 and inertial 42 components.
- Elements in FIG. 5 having the same function as elements shown in FIG. 4 have like numbers.
- a temperature sensor 46 in or on the side wall of pulse tube 18 , or in the gas inside of the side wall of pulse tube 18 is located to provide a control temperature of the working gas that is useful for maintaining a selected phase angle.
- An exemplary location of sensor 46 that is axially midway between the cold end and the ambient end of pulse tube 18 gives a very convenient measure of Rayleigh streaming in pulse tube 18 .
- sensor 46 at the mid-point location indicates a temperature nearly equal to the average of the ambient and cold temperatures, the Rayleigh streaming is nearly stopped. If the mid-point temperature is well above the average, the Rayleigh streaming is down along the side wall of pulse tube 18 and up in the center. If the mid-point temperature is well below the average of the ambient and cold temperatures, the Rayleigh streaming is up along the side wall of pulse tube 18 and down in the center.
- such a sensor is readily used to provide feedback through controller 48 for controlling valves 34 , 36 and the concomitant fluid 32 flow rate through fluid jackets 30 , 31 for the system shown in FIG. 4.
- controller 48 for controlling valves 34 , 36 and the concomitant fluid 32 flow rate through fluid jackets 30 , 31 for the system shown in FIG. 4.
- heaters 130 , 131 are selectively energized for the system shown in FIG. 5A; flow control valve 134 is adjusted for the system shown in FIG. 5B.
- the mid-point temperature along pulse tube 18 provides generally a linear signal and is a preferred signal
- other temperatures in the pulse tube refrigerator may be used.
- the sensor might sense the temperature of cold heat exchanger 26 and output a control signal that maintains a cold output temperature. It should be noted that such other temperatures may be non-linear and provide a more difficult control signal.
- Temperature control of the operating gas may also provide fine tuning for Rayleigh streaming suppression in the thermal buffer column in a piston-less Stirling device, as described in U.S. Pat. No. 6,032,464 “Traveling Wave Device with Mass Flux Suppression” (Swift et al.), incorporated herein by reference.
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Abstract
Description
- [0001] This invention was made with government support under Contract No. W7405-ENG-36 awarded by the U.S. Department of Energy. The government has certain rights in the invention.
- The present invention relates generally to orifice pulse tube refrigerators, and, more particularly, to orifice pulse tube refrigerators with reduced Rayleigh streaming in the pulse tube.
- Orifice pulse tube refrigeration is the most rapidly developing field of cryogenic refrigeration today. The high efficiency of a Stirling-based thermodynamic cycle, the lack of moving parts at cryogenic temperature, and the lack of small, easily plugged orifices at cryogenic temperature combine to make this new technology inexpensive and reliable. Furthermore, orifice pulse tube refrigerators can be driven by thermoacoustic heat engines, creating for the first time cryogenic refrigeration with no moving parts. Background information about orifice pulse tube refrigerators is given, for example, by R. Radebaugh, “A review of pulse tube refrigeration,” pages 1191-1205 in Adv. Cryogenic Eng., Volume 35 (1990), and in R. Radebaugh, “Advances in Cryocoolers,” 1997, pages 33-44 in the Proceedings of the Sixteenth International Cryogenic Engineering Conference/lnternational Cryogenic Materials Conference (ICEC16/ICMC), edited by T. Haruyama et al., (Elsevier, Oxford, 1997), all incorporated herein by reference.
- A prior art orifice pulse tube refrigerator is shown schematically in FIG. 1A. One of the key parameters in an operational orifice pulse tube refrigerator is the temporal phase difference between oscillating pressure and oscillating velocity. The reference convention used herein is that x is the distance from the driver along the axis of the refrigerator, that positive velocity is velocity in the positive x direction, and that θ is the temporal phase angle by which oscillating pressure leads oscillating velocity. This temporal phase θ is also called the phase of the complex acoustic impedance Z. It is well known that θ is a function of x, due for example, to the compressibility of the gas in various portions of the refrigerator.
- Relative magnitudes and phases are conventionally displayed in a phasor diagram, such as shown in FIG. 1B. FIG. 1B illustrates, for example, the viscous pressure drop across
regenerator 12, which manifests itself as the difference between the pressure phasor P1,driver atdriver 10 and the pressure phasor P1,pulse tube inpulse tube 18. The difference between the volume flow rate phasor U1,ambient heat exchanger atambient heat exchanger 28 and the volume flow rate phasor U1,cold atcold heat exchanger 26 is due to the compressibility of the gas inpulse tube 18. In FIG. 1B, P1,ambient heat exchanger can be assumed nearly identical to P1,pulse tube, so θambient heat exchanger is the angle by which P1,pulse tube leads U1,ambient heat exchanger, which is approximately 50 degrees in FIG. 1B. This is a typical value for an orifice pulse tube refrigerator with an inertial impedance (“inertance”). - Continuing to refer to FIGS. 1A and 1B, it is well known that the entire phase distribution θ(x) throughout an orifice pulse tube refrigerator, and, in particular, in
regenerator 12, can be controlled by means ofinertance 14 andflow resistances pulse tube 18 of the orifice pulse tube refrigerator. An early published reference to this use of inertance was by S. W. Zhu et al., “Phase shift effect of the long neck tube for the pulse tube refrigerator,” in the Proceedings of Cryocoolers 9, held June 1996 in New Hampshire. An adjustable version of such an acoustic impedance network with inertance is described by D. L. Gardner et al., “Use of inertance in orifice pulse tube refrigerators,” Cryogenics, Volume 37, pages 117-121 (1997) and G. W. Swift et al., “Pulse Tube Refrigerator With Variable Phase Shift,” U.S. Pat. No. 6,021,643, Feb. 8, 2000, all incorporated herein by reference. In the '643 patent, a variable acoustic impedance network, as shown atoppulse tube 18 in FIG. 1A, is described, comprising aninertance tube 14, acompliance volume 22, and two adjustableflow resistance valves - FIG. 2, which is a reproduction of FIG. 7 from the '643 patent, shows the broad range of θambient heat exchanger accessible by this method. The points on FIG. 2 show some typical values of acoustic impedance Z at the top of the pulse tube, experimentally accessed by adjusting the two
valves inertance 14, all values of Z between the two horizontal dashed lines would be accessible, and the experimental reality is not far from that ideal. The values of θ represented by these points range from about zero to 80 degrees (the angle between the horizontal axis and a line from the origin to a given point). - The three large circles on FIG. 2 are contours of constant power dissipation in the
acoustic impedance network cold heat exchanger 26. Then, an operating point for the orifice pulse tube refrigerator is uniquely defined by, and is often chosen by, selecting a gross cooling power, i.e., at which circle one wants to operate, and a value of θ. The actual net refrigerating power is the gross cooling power minus the sum of heat leaks tocold heat exchanger 26. Imperfect operation ofregenerator 12 and imperfect operation ofpulse tube 18 are two sources of potentially large heat leaks, but proper design can minimize these. Efficient refrigeration also requires little viscous dissipation inregenerator 12. - It is well known that refrigeration occurs only if θ lies between plus 90 degrees and minus 90 degrees in
regenerator 12, and that both regenerator heat leak and viscous dissipation are minimized by keeping θ as close to zero degrees as possible throughoutregenerator 12. In a cryogenic orifice pulse tube refrigerator, typically θ is between zero and minus 45 degrees at the ambient end of the regenerator, passes through zero somewhere within the regenerator, and is positive and less than 45 degrees at the cold end of the regenerator. However, the sensitivity of regenerator efficiency to the exact values of θ(x) is not too strong, and a regenerator with θ(x) shifted by 10 or even 20 degrees from the optimal values may not have a noticeable loss in efficiency with respect to either viscous dissipation or heat leak. - The temporal phase θ also plays an important role in the efficiency of the pulse tube of the orifice pulse tube refrigerator. Pulse tubes are susceptible to an internal, toroidal steady convection, called Rayleigh streaming, that is superimposed upon the desired oscillatory motion. Rayleigh streaming reduces the efficiency of orifice pulse tube refrigerators because the streaming convects heat from
ambient heat exchanger 28atop pulse tube 18 to cold heat-exchanger 26 at the bottom ofpulse tube 18, thereby reducing the cooling power of the orifice pulse tube refrigerator. Rayleigh streaming is caused by boundary-layer processes at the side walls of the pulse tube, which are controlled by various parameters including phase angle θ, the taper angle of the pulse tube, and properties of the working gas, as described by J. R. Olson et al., “Acoustic streaming in pulse tube refrigerators: Tapered pulse tubes,” Cryogenics, Volume 37, pages 769-776 (1997) and G. W. Swift et al., “Tapered pulse tube for pulse tube refrigerators,” U.S. Pat. No. 5,953,920, Sep. 21, 1999, all incorporated herein by reference. All other variables being fixed, there is at most one value of θ that stops Rayleigh streaming. - Rayleigh streaming is extremely sensitive to the value of θ, as shown in FIG. 3, from G. W. Swift et al., “Performance of a tapered pulse tube,” pages 315-320 in Cryocoolers 10, edited by R. G. Ross Jr. (Kluwer Academic/Plenum Publishers, 1999), incorporated herein by reference. This experimental evidence shows that a 3 degree change in θ away from the optimum value can cause enough Rayleigh streaming to consume 10% of the gross cooling power of the orifice pulse tube refrigerator. A 3 degree change in θ is small enough that it would have no significant effect on the regenerator efficiency.
- The temporal phase θ can be adjusted, as described in the '643 patent, but there is no need for such a large range of adjustability when nominally identical orifice pulse tube refrigerators are mass produced for nominally identical applications. In such a circumstance, an acoustic impedance network with geometrically fixed components would be much cheaper than the high-pressure bellows-sealed valves described in Swift et al., supra. For automated control, expensive high-torque valve actuators may also be needed to adjust the resistances automatically. However, it is often necessary to provide fine-tuning adjustment of the acoustic impedance network, because of the sensitivity of Rayleigh streaming to the conditions of operation. Even nominally identical orifice pulse tube refrigerators that are mass produced for nominally identical applications may suffer from minor unit-to-unit construction variations or from diurnal and seasonal variations in ambient temperature.
- Hence, it is desirable to provide fine-tuning adjustments to the value of θ in the pulse tubes of orifice pulse tube refrigerators. It is further desirable to provide for the fine-tuning adjustments with inexpensive hardware.
- Various advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
- The present invention includes an orifice pulse tube refrigerator having flow resistance, compliance, and inertance components connected to a pulse tube for establishing a phase relationship between oscillating pressure and oscillating velocity in the pulse tube. A temperature regulating system heats or cools a working gas in at least one of the flow resistance and inertance components. A temperature control system is connected to the temperature regulating system for controlling the temperature of the working gas in the at least one of the flow resistance and inertance components and maintains a control temperature that is indicative of a desired temporal phase relationship.
- The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
- FIGS. 1A and 1B schematically depict a prior art orifice pulse tube refrigerator having an inertance and a phasor diagram of the phase relationships in the refrigerator.
- FIG. 2 graphically depicts the broad range of impedance Z and phase θ values atop the pulse tube that can be obtained by adjusting resistive valves in a typical acoustic impedance network.
- FIG. 3 graphically depicts the heat leak in one pulse tube as a function of phase θ.
- FIG. 4 schematically depicts an orifice pulse tube refrigerator with an exemplary system for fine tuning the phase θ according to the present invention.
- FIGS. 5A and 5B schematically depict orifice pulse tube refrigerators with two other systems for fine tuning the phase θ according to the present invention.
- In accordance with an exemplary embodiment of the present invention, as shown in FIG. 4, some or all of the elements of the acoustic impedance network atop
pulse tube 18 can be enclosed withtemperature control jackets fluid 32, whose flow rate can be controlled, e.g., byvalves - The inertial impedance of an inertance tube is equal to the product of the gas density times the cross sectional area divided by the length of the tube, and the gas density is proportional to the absolute temperature. Thus, the temperature of the working gas provides a significant control of
inertance 42, which contributes to the imaginary part of Z—the vertical axis in FIG. 2. The resistive impedance of a resistive valve, fixed orifice, flow impedance, orother flow resistance 38 depends on the viscosity of the gas, which, in turn, is typically proportional to the 0.7 power of the absolute temperature. Again, the temperature of the working gas provides a significant control of the resistive impedance, which contributes to the real part of Z—the horizontal axis in FIG. 2. The compliance ofcompliance tank 44 is independent of temperature. The temperatures of the working gas in these components is determined by a balance among dissipation of acoustic power into heat within these components; thermoacoustic transport of heat through the working gas to or from these components, from or to adjacent components; and the temperatures of the solid surfaces of the components. Hence, the present invention provides for varying flow resistance and/or inertance of the acoustic impedance network by varying the temperature of the working gas in at least one of these components in an orifice pulse tube refrigerator. - All orifice pulse tube refrigerators reject waste heat to ambient temperature, usually to a flowing stream of ambient water or ambient air. Either of these two fluids can be used in
temperature control jackets temperature control fluid 32 by means ofvalves - If the orifice pulse tube refrigerator is driven by a combustion-powered thermoacoustic engine, flue gas could be used as the fluid32 whose flow through
jackets - Alternatively, as shown in FIG. 5A,
heaters temperature control jackets Heaters valve 134 to adjustfluid flow 132 to thereby regulate the temperature ofambient heat exchanger 128 atop the pulse tube. This alternative relies on the thermoacoustic thermal connection in the working gas betweenambient heat exchanger 128 and resistive 38 and inertial 42 components to control the temperatures of resistive 38 and inertial 42 components. Elements in FIG. 5 having the same function as elements shown in FIG. 4 have like numbers. - A
temperature sensor 46 in or on the side wall ofpulse tube 18, or in the gas inside of the side wall ofpulse tube 18 is located to provide a control temperature of the working gas that is useful for maintaining a selected phase angle. An exemplary location ofsensor 46 that is axially midway between the cold end and the ambient end ofpulse tube 18 gives a very convenient measure of Rayleigh streaming inpulse tube 18. Whensensor 46 at the mid-point location indicates a temperature nearly equal to the average of the ambient and cold temperatures, the Rayleigh streaming is nearly stopped. If the mid-point temperature is well above the average, the Rayleigh streaming is down along the side wall ofpulse tube 18 and up in the center. If the mid-point temperature is well below the average of the ambient and cold temperatures, the Rayleigh streaming is up along the side wall ofpulse tube 18 and down in the center. - For example, such a sensor is readily used to provide feedback through
controller 48 for controllingvalves concomitant fluid 32 flow rate throughfluid jackets heaters control valve 134 is adjusted for the system shown in FIG. 5B. - While the mid-point temperature along
pulse tube 18 provides generally a linear signal and is a preferred signal, other temperatures in the pulse tube refrigerator may be used. For example, the sensor might sense the temperature ofcold heat exchanger 26 and output a control signal that maintains a cold output temperature. It should be noted that such other temperatures may be non-linear and provide a more difficult control signal. - Temperature control of the operating gas may also provide fine tuning for Rayleigh streaming suppression in the thermal buffer column in a piston-less Stirling device, as described in U.S. Pat. No. 6,032,464 “Traveling Wave Device with Mass Flux Suppression” (Swift et al.), incorporated herein by reference.
- The foregoing description of the invention has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.
Claims (12)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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US10/163,781 US6666033B1 (en) | 2002-06-06 | 2002-06-06 | Method and apparatus for fine tuning an orifice pulse tube refrigerator |
PCT/US2003/017422 WO2003104725A1 (en) | 2002-06-06 | 2003-06-03 | Method and apparatus for fine tuning an orifice pulse tube refrigerator |
AU2003240501A AU2003240501A1 (en) | 2002-06-06 | 2003-06-03 | Method and apparatus for fine tuning an orifice pulse tube refrigerator |
Applications Claiming Priority (1)
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US10/163,781 US6666033B1 (en) | 2002-06-06 | 2002-06-06 | Method and apparatus for fine tuning an orifice pulse tube refrigerator |
Publications (2)
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US20030226364A1 true US20030226364A1 (en) | 2003-12-11 |
US6666033B1 US6666033B1 (en) | 2003-12-23 |
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US10/163,781 Expired - Fee Related US6666033B1 (en) | 2002-06-06 | 2002-06-06 | Method and apparatus for fine tuning an orifice pulse tube refrigerator |
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US (1) | US6666033B1 (en) |
AU (1) | AU2003240501A1 (en) |
WO (1) | WO2003104725A1 (en) |
Cited By (10)
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US20070044484A1 (en) * | 2005-08-23 | 2007-03-01 | Sunpower, Inc. | Pulse tube cooler having 1/4 wavelength resonator tube instead of reservoir |
WO2008036920A2 (en) * | 2006-09-22 | 2008-03-27 | Praxair Technology, Inc. | Control method for pulse tube cryocooler |
GB2447555A (en) * | 2007-03-14 | 2008-09-17 | Schlumberger Holdings | Cooling systems for downhole tools |
US20110023500A1 (en) * | 2009-07-31 | 2011-02-03 | Palo Alto Research Center Incorporated | Thermo-Electro-Acoustic Refrigerator And Method Of Using Same |
US20110025073A1 (en) * | 2009-07-31 | 2011-02-03 | Palo Alto Research Center Incorporated | Thermo-Electro-Acoustic Engine And Method Of Using Same |
US8375729B2 (en) | 2010-04-30 | 2013-02-19 | Palo Alto Research Center Incorporated | Optimization of a thermoacoustic apparatus based on operating conditions and selected user input |
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WO2003079042A2 (en) * | 2002-03-13 | 2003-09-25 | Georgia Tech Research Corporation | Travelling-wave thermoacoustic engines with internal combustion and associated methods |
US6865894B1 (en) * | 2002-03-28 | 2005-03-15 | Lockheed Martin Corporation | Cold inertance tube for multi-stage pulse tube cryocooler |
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US20070044484A1 (en) * | 2005-08-23 | 2007-03-01 | Sunpower, Inc. | Pulse tube cooler having 1/4 wavelength resonator tube instead of reservoir |
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US20080072608A1 (en) * | 2006-09-22 | 2008-03-27 | Bryce Mark Rampersad | Control method for pulse tube cryocooler |
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US20110023500A1 (en) * | 2009-07-31 | 2011-02-03 | Palo Alto Research Center Incorporated | Thermo-Electro-Acoustic Refrigerator And Method Of Using Same |
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US8205459B2 (en) * | 2009-07-31 | 2012-06-26 | Palo Alto Research Center Incorporated | Thermo-electro-acoustic refrigerator and method of using same |
US8227928B2 (en) | 2009-07-31 | 2012-07-24 | Palo Alto Research Center Incorporated | Thermo-electro-acoustic engine and method of using same |
US8375729B2 (en) | 2010-04-30 | 2013-02-19 | Palo Alto Research Center Incorporated | Optimization of a thermoacoustic apparatus based on operating conditions and selected user input |
US8584471B2 (en) | 2010-04-30 | 2013-11-19 | Palo Alto Research | Thermoacoustic apparatus with series-connected stages |
CN106288481A (en) * | 2016-09-22 | 2017-01-04 | 浙江大学 | A kind of Cryo Refrigerator being connected compressor and regenerator by transfer tube |
US11041458B2 (en) * | 2017-06-15 | 2021-06-22 | Etalim Inc. | Thermoacoustic transducer apparatus including a working volume and reservoir volume in fluid communication through a conduit |
US11181956B2 (en) * | 2017-08-30 | 2021-11-23 | New H3C Information Technologies Co., Ltd. | Controlling fan speed of server |
Also Published As
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WO2003104725A1 (en) | 2003-12-18 |
US6666033B1 (en) | 2003-12-23 |
AU2003240501A1 (en) | 2003-12-22 |
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