PATENT DOCUMENT

Abstract:
The present disclosure details a thermoacoustic driven compressor having a pressurized housing, which contains within a thermoacoustic engine and a working gas, coupled to a positive displacement reciprocating compressor. The thermoacoustic driven compressor generates scalable compressed air from a given heat source.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    N/A 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    N/A 
       THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    N/A 
       INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
       [0004]    N/A 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    The present disclosure relates to systems and methods for utilizing a thermoacoustic engine with a positive displacement reciprocating compressor. 
         [0007]    2. Background of the Invention 
         [0008]    Due to the increasing costs and environmental concerns associated with hydrocarbon-based energy, society has recently shown greater interest in technologies that promote energy efficiency and alternative sources of energy. One technology that shows great promise in both fields is a thermoacoustic prime mover, which converts heat from any source to acoustic energy (i.e., an acoustic pressure wave). 
         [0009]    In general, a thermoacoustic engine consists of a hermetically sealed cylinder housing (often referred to as a resonating tube) containing a pressurized noble gas (e.g., helium or argon). Attached to the inner wall of the cylinder housing is the thermoacoustic engine core. Depending on the configuration, the engine core can induce either a standing or traveling pressure wave in the gas medium. 
         [0010]    In the standing wave case, the engine core can consist of a stack sandwiched between a hot and cold exchanger. The stack typically is a porous solid spanning both temperature extremes through which gas oscillates. One characteristic of such a stack is that the pores of the stack are similar in size to the thermal penetration depth of the gas. To start the engine, hot and cold sources are applied to the hot and cold exchangers, respectively. The large temperature gradient created between these two exchangers causes the gas in the stack to channel heat from the hot to the cold end (per the Second Law of Thermodynamics). This oscillating expansion and contraction of gas between exchangers is what creates the acoustic pressure wave. The standing wave time phasing characteristics are due to very poor thermal contact between the gas and the stack (e.g., because of large pore size), which allows gas pressure and relative gas displacement oscillations to be in phase with the gas thermal expansion and contraction. 
         [0011]    In contrast to a stack-derived thermoacoustic engine core, a traveling wave engine core incorporates a regenerator, which can also be sandwiched between a hot and cold exchanger. The regenerator, just like the stack, is typically a porous solid spanning both temperature extremes through which gas oscillates. However, in this case the pores are usually much smaller than the thermal penetration depth of the gas. The excellent contact between the porous material and the gas provides for more efficient heat transfer. The improved efficiency allows the oscillating gas thermal expansions and contractions to be in phase with the gas pressure and relative gas velocity oscillations. Another differentiating factor is that the regenerator functions as an amplifier of acoustic power. This acoustic power can be provided by a number of devices, including, but not limited to, a torus shaped resonator (see, e.g., U.S. Pat. Nos. 6,032,464 and 6,314,740), and a cascaded stack (see, e.g., U.S. Pat. No. 6,658,862). An alternative means of facilitating traveling wave time phasing with a regenerator is through the use of a bellows (see, e.g., U.S. Pat. No. 7,143,586 B2). 
         [0012]    It is also known in the art that the pressure wave of a thermoacoustic prime mover can be used to reciprocate a mass element (e.g., a piston; see Grant, “Investigation of the Physical Characteristics of a Mass Element Resonator”, M.S. Thesis, Naval Postgraduate School, Monterey, Calif., 1992, National Technical Information Service ADA251792). Furthermore, an electrodynamic linear alternator can be used to convert this mechanical energy to electrical energy (see, e.g., U.S. Pat. Nos. 4,623,808 and 5,389,844). While much discussion has focused on using this electrical energy for space probes and to a lesser extent grid power, one application that has greater potential is electrical compression. Unfortunately, for larger scale compression purposes, this configuration is not practical due to the cost, complexity, and the large number of linear alternators needed. 
         [0013]    A related field to the linear alternator is the linear motor compressor (see, e.g., U.S. Pat. No. 5,257,915). However, this device exhibits similar shortcomings, such as complexity and cost. 
         [0014]    Therefore, it is apparent that there exists a need to generate larger volumes of compression on a more economical and robust scale via thermoacoustics. 
       SUMMARY OF THE INVENTION 
       [0015]    The present disclosure provides a thermoacoustic compressor, comprising a first housing having a first end, a second end, an inner wall, and an outer wall, the first housing defining a first cavity, and the second end of the first housing defining a first piston rod aperture, a second housing having a first end, a second end, an inner wall, and an outer wall, the first end of the second housing operably connected to the second end of the first housing, the second housing comprising pressurized gas or fluid and defining a second cavity, and the first end of the second housing defining a second piston rod aperture, a reciprocating piston axially movable within the first and second cavities, the reciprocating piston comprising a compression piston head having a first end, a second end, and an outer wall, the compression piston head disposed in the first cavity, the first end of the compression piston head and the first end of the first housing defining a first variable-volume chamber, and the second end of the compression piston head and the second end of the first housing defining a second variable-volume chamber, a piston rod having a first end and a second end, the first end of the piston rod connected to the second end of the compression piston head, and a resonating piston head having a first end, a second end, and an outer wall, the resonating piston head disposed in the second cavity, the first end of the resonating piston head and the first end of the second housing defining a third variable-volume chamber, and the second end of the resonating piston head and the second end of the second housing defining a fourth variable-volume chamber, the first end of the resonating piston head connected to the second end of the piston rod, a valved intake port and a valved discharge port on the first end of the first housing, a thermoacoustic engine connected to the inner wall of the second housing positioned between the second end of the resonating piston head and the second end of the second housing, and, for example, perpendicular to the resonating piston head and spanning the cross-sectional area of the second housing, a means for inhibiting gas flow between the first and the second housing, a means for providing or delivering heat to the thermoacoustic engine, and a means for removing heat from the thermoacoustic engine. 
         [0016]    In certain embodiments, the compression piston head comprises at least a first sealing means disposed between the outer wall of the compression piston head and the inner wall of the first housing. In particular embodiments, the at least a first sealing means of the compression piston head comprises at least a first piston ring disposed within a first groove or seat formed in the outer wall of the compression piston head. In certain aspects, the at least a first piston ring is coated, for example with polytetrafluoroethylene. In further embodiments, the at least a first piston ring is made from metal, for example cast iron, aluminum, or an alloy, a composite material, a plastic material, or a composite plastic material, for example polytetrafluoroethylene, polyetheretherketone, or polyphenylene sulfide, or any combination thereof. In particular aspects, the composite plastic material comprises a filler, for example white glass, glass molybdenum, glass graphite, carbon, polyetheretherketone, bronze, bronze molybdenum, polyphenylene sulfide, molybdenum, or any combination thereof. In other embodiments, the compression piston head further comprises a biasing means disposed within the first groove for forcing the at least a first piston ring against the inner wall of the first housing. 
         [0017]    In certain embodiments, the thermoacoustic compressor further comprises a guiding means for guiding the compression piston head in the first cavity. In particular aspects, the guiding means comprises at least a first guide ring disposed within a second groove formed in the outer wall of the compression piston head. In further embodiments, the at least a first guide ring is coated, for example with polytetrafluoroethylene. In other embodiments, the at least a first guide ring is made from metal, for example cast iron, aluminum, or an alloy, a composite material, a plastic material, or a composite plastic material, for example polytetrafluoroethylene, polyetheretherketone, or polyphenylene sulfide, or any combination thereof. In certain aspects, the composite plastic material comprises a filler, for example white glass, glass molybdenum, glass graphite, carbon, polyetheretherketone, bronze, bronze molybdenum, polyphenylene sulfide, molybdenum, or any combination thereof. 
         [0018]    In particular embodiments, the compression piston head is coated, for example with polytetrafluoroethylene. In other embodiments, the compression piston head is lubricated, for example oil lubricated. In these embodiments, the compression piston head may further comprise a means for removing lubricant from the inner wall of the first housing, for example at least a first scraper ring, which may be disposed within a third groove formed in the outer wall of the compression piston head. In certain embodiments, the thermoacoustic compressor further comprises a collection chamber located proximal to the second end of the first housing. In these embodiments, the first housing may further comprise a pressure lubricating system, which in certain aspects may comprise a pump, a filter, a lubricant line, a lubricant dispenser, a spray nozzle, or any combination thereof. 
         [0019]    In certain aspects, the first housing, second housing, and/or reciprocating piston is made from metal, for example iron, cast iron, nodular cast iron, ductile iron, gray iron, aluminum, steel, cast steel, forged steel, stainless steel, for example 304, 316, 316L, 316H, 410, or 419 stainless steel, carbon steel, bronze, an alloy, for example a nickel-based alloy, such as a 625 alloy, an INCONEL® alloy, or an INCONEL® 625 alloy, or a combination thereof. In further embodiments, the inner wall of the first housing is coated, for example with polytetrafluoroethylene. In other aspects, the first housing further comprises a cooling means, for example at least a first water jacket located around the first housing, at least a first water jacket located in a cavity between the inner wall and the outer wall of the first housing, and/or at least a first air fin located on the outer wall of the first housing. 
         [0020]    In particular aspects, the thermoacoustic compressor further comprises a displacement control and return means within the first housing, which in certain aspects may comprise at least a first mechanical spring located between the second end of the compression piston head and the second end of the first housing, or a variable-volume balance chamber within the first housing located between the second end of the compression piston head and the second end of the first housing. In these aspects, the thermoacoustic compressor may further comprise a porting means, for example a groove in the inner wall of the first housing, in fluid communication between the variable-volume balance chamber and the variable-volume compression chamber, or further comprise a mechanical spring disposed in a groove in the inner wall of the variable-volume balance chamber between the second end of the compression piston head and the second end of the first housing. 
         [0021]    In certain embodiments, the means for inhibiting gas flow between the first and the second housings is a seal disposed about the piston rod and located in the first piston rod aperture or the second piston rod aperture. In particular aspects, the seal comprises packing, for example an oil wiper or pressure packing, which may be cooled, for example water cooled or cooled using a heat conducting sleeve, such as a Thermosleeve™. In these aspects, the thermoacoustic compressor may further comprise a purging line connected to the oil wiper or pressure packing and a purging canister, which may comprise the same pressurized gas as the second housing, connected to the purging line comprising pressurized gas or fluid, or may further comprise a venting line connected to the oil wiper or pressure packing and extending to an environment external of the first or second housing. In further embodiments, the venting line extends through the outer wall of the first or second housing. 
         [0022]    In other embodiments, the first and/or second housing comprises at least a first lubricating strip between the first and/or second housing and the piston rod. In further embodiments, the second housing further comprises a displacement control and return means, which may comprise at least a first mechanical spring located between the first end of the resonating piston head and the first end of the second housing, or a variable-volume balance chamber within the second housing located between the first end of the resonating piston head and the first end of the second housing, in which case the thermoacoustic compressor may further comprise a mechanical spring disposed in a groove in the inner wall of the variable-volume balance chamber between the first end of the resonating piston head and the first end of the second housing. In yet other embodiments, the inner wall of the second housing and/or resonating piston head is coated, for example with polytetrafluoroethylene. In still other embodiments, the resonating piston head is tightly fitted within the second cavity. 
         [0023]    In further embodiments, the resonating piston head comprises at least a first piston ring disposed within a first groove formed in the outer wall of the resonating piston head. In certain embodiments, the at least a first piston ring is a piston sealing or guide ring. In particular aspects, the at least a first piston ring is coated, for example with polytetrafluoroethylene. In other embodiments, the at least a first piston ring is made from metal, for example cast iron, aluminum, or an alloy, a composite material, a plastic material, or a composite plastic material, for example polytetrafluoroethylene, polyetheretherketone, or polyphenylene sulfide, or any combination thereof. In yet other embodiments, the composite plastic material comprises a filler, which may comprise white glass, glass molybdenum, glass graphite, carbon, polyetheretherketone, bronze, bronze molybdenum, polyphenylene sulfide, molybdenum, or any combination thereof. In additional embodiments, the resonating piston head further comprises a biasing means disposed within a first groove formed in the outer wall of the resonating piston head for forcing the at least a first piston ring against the inner wall of the second housing. 
         [0024]    In certain embodiments, the means for providing or delivering heat to the thermoacoustic engine comprises heating metal wiring. In other embodiments, the means for providing or delivering heat to the thermoacoustic engine comprises a heated fluid and piping. In such embodiments, the means for providing or delivering heat to the thermoacoustic engine may further comprise a pump, may further comprise a heat recovery or exchanger unit, which may comprise pumping a heated fluid through piping from a heat recovery or exchanger unit. In further embodiments, the means for removing heat from the thermoacoustic engine comprises cooling fluid and piping. In these embodiments, the means for removing heat from the thermoacoustic engine may further comprise a pump, and further comprise a heat recovery or exchanger unit, which may comprise pumping a cooling fluid through piping to a heat recovery or exchanger unit. In yet other embodiments, the means for removing heat from the thermoacoustic engine further comprises at least a first fan. 
         [0025]    In particular aspects, the thermoacoustic compressor further comprises a dehumidifying means, for example a scrubber, a desiccant dryer, or a refrigeration means, such as thermoacoustic or Stirling refrigeration, in fluid communication with the valved discharge port. In other aspects, the thermoacoustic compressor further comprises an intercooler in fluid communication with the valved discharge port, a pulsation tube in fluid communication with the valved discharge port, and/or a lubricant removing means, which may comprise a coalescer, in fluid communication with the valved discharge port. In further aspects, the thermoacoustic compressor further comprises a means for storing compressed fluid in fluid communication with the valved discharge port, and/or a heating means, for example a heat recovery unit or a heat exchanger, in fluid communication with the valved discharge port. In still further aspects, the thermoacoustic compressor further comprises a filter in fluid communication with the valved intake port, and/or a refrigeration means, for example thermoacoustic or Stirling refrigeration, in fluid communication with the valved intake port. 
         [0026]    In certain embodiments, the thermoacoustic engine comprises a thermoacoustic core. In such embodiments, the thermoacoustic core may comprise a hot exchanger, which may comprise a shell-and-tube or finned-tube design, a cold exchanger, which may comprise a shell-and-tube or finned-tube, or circulating heat exchanger design, and a stack. In particular embodiments, the hot and/or cold exchanger is made from metal, for example stainless steel, such as 304 stainless steel, 316 stainless steel, 316L stainless steel, 316H stainless steel, 409 stainless steel, or  419  stainless steel, or a combination thereof, carbon steel, aluminum, an alloy, for example a nickel-based alloy, a nickel-based  625  alloy, or an INCONEL® 625 alloy, copper, tellurium copper, oxygen-free high conductivity copper, or a combination thereof. In further embodiments, the stack comprises a honeycomb, stacked screen, parallel-plate, random fiber, foam, foil roll/stack, or packed sphere design. In other aspects, the stack is made from carbon nanotubes, a ceramic, a composite, glass, metal hydrides, phase exchange materials, nanoparticles, or metal, such as stainless steel, carbon steel, aluminum, an alloy, or a combination thereof. In other such embodiments, the thermoacoustic engine core may comprise a hot exchanger, a cold exchanger, and a regenerator. In these embodiments, the hot exchanger may be downstream of the regenerator. In certain aspects, the regenerator comprises a honeycomb, stacked screen, or parallel-plate design. In other aspects, the regenerator is made from carbon nanotubes or metal, for example stainless steel, carbon steel, aluminum, an alloy, or a combination thereof. 
         [0027]    In particular embodiments, the second housing comprises or defines a torus, which may define an acoustic compliance portion and an inertance portion, which may comprise a polished inside surface and/or a pressure balancing sliding joint. In these embodiments, the thermoacoustic compressor may further comprise a max flux suppressor within the torus, and/or a thermal buffer tube adjacent to the hot exchanger opposite the regenerator. In certain aspects, the thermal buffer tube is made from carbon nanotubes or metal, such as stainless steel, carbon steel, aluminum, an alloy, or a combination thereof. In other aspects, the thermal buffer tube comprises a polished inside surface, at least a first flow straightener, and/or is tapered. In yet other aspects, the length of the thermal buffer tube is greater than the peak-to-peak fluid displacement amplitude. In certain embodiments, the thermoacoustic engine further comprises an ambient heat exchanger for residual heat leaks, and/or further comprises a bellows. 
         [0028]    In certain embodiments, the resonating and/or compression piston head is flat, truncated cone-shaped, shaped like the cross-section of an isosceles trapezoid, hemi-elliptical shaped, or a combination thereof. In particular embodiments, the resonating and/or compression piston head is solid or hollow. In other embodiments, the thermoacoustic compressor further comprises a second valved intake port and a second valved discharge port on the second end of the first housing. In still other embodiments, the first end of the second housing is physically mated to the second end of the first housing. 
         [0029]    In additional embodiments, the thermoacoustic compressor further comprises a third housing having a first end, a second end, an inner wall, and an outer wall, the first end of the second housing operably connected to the second end of the third housing, the second end of the first housing operably connected to the first end of the third housing, the third housing defining a third cavity, the first end of the third housing defining a third piston rod aperture, and the second end of the third housing defining a fourth piston rod aperture. In particular aspects, the third housing further comprises a displacement control and return means, which may comprise at least a first mechanical spring, at least a first gas spring, or at least a first mechanical spring and at least a first gas spring. In further aspects, the third housing is made from metal, for example iron, cast iron, nodular cast iron, aluminum, steel, cast steel, forged steel, stainless steel, carbon steel, bronze, an alloy, or a combination thereof. In other aspects, the inner wall of the third housing is coated, for example with polytetrafluoroethylene. In yet other aspects, the inner wall of the third housing comprises a cylinder liner, for example a replaceable cylinder liner. In still other aspects, the cylinder liner is coated, for example with polytetrafluoroethylene. In certain aspects, the third housing comprises at least a first sealable access hole. 
         [0030]    In other embodiments, the second housing further comprises a plurality of thermoacoustic engines in series. In certain embodiments, the second housing further comprises at least one region of high specific acoustic impedance in an acoustic wave. In such embodiments, the second housing may further comprise a plurality of thermoacoustic engines in series within the at least one region of high specific acoustic impedance. In particular embodiments, the at least a first of the plurality of thermoacoustic engines is a stack and at least a second of the plurality of thermoacoustic engines is a regenerator. In other embodiments, the second housing defines a first area having a first cross-sectional area and a second area having a second cross-sectional area. In such embodiments, the cross-sectional area of the first cross-sectional area may be the same or different than the cross-sectional area of the second cross-sectional area. In yet other embodiments, the second housing further defines a third area having a third cross-sectional area between the first area having a first cross-sectional area and the second area having a second cross-sectional area, thereby creating a plurality of regions of high acoustic impedance. In still other embodiments, the thermoacoustic compressor comprises a thermal buffer tube adjacent to at least one of the plurality of thermoacoustic engines. In certain aspects, the thermal buffer tube is tapered, while in other aspects the thermal buffer tube connects a first and a second of the plurality of thermoacoustic engines. In further aspects, the second housing comprises a plurality of regions of high specific acoustic impedance along a common axis. In such aspects, the at least a first of the plurality of regions of high specific acoustic impedance may comprise a plurality of thermoacoustic engines in series and at least a second of the plurality of regions of high specific acoustic impedance comprises a plurality of thermoacoustic engines in series, or the at least a first and at least a second of the plurality of regions of high specific acoustic impedance may be separated by an acoustic side branch, thereby creating an axially extended region of high acoustic impedance. 
         [0031]    In further embodiments, the first, second, and/or third housing comprises at least a first sealable access hole. In other embodiments, the first, second and third housing each comprise at least a first sealable access hole. In particular embodiments, the inner wall of the first, second, and/or third housing comprises a cylinder liner, for example a replaceable cylinder liner and/or a coated cylinder liner. In other embodiments, the intake and/or discharge valve is corrosion resistant, for example the intake valve may be made from stainless steel. 
         [0032]    In certain aspects, the thermoacoustic compressor further comprises a gas or fluid bearing disposed in a clearance gap between the outer wall of the compression piston and the inner wall of the first housing, while in other aspects the thermoacoustic compressor further comprises a gas or fluid bearing disposed in a clearance gap between the outer wall of the resonating piston and the inner wall of the second housing. In particular aspects, the thermoacoustic compressor further comprises a first gas or fluid bearing disposed in a clearance gap between the outer wall of the compression piston and the inner wall of the first housing and a second gas or fluid bearing disposed in a clearance gap between the outer wall of the resonating piston and the inner wall of the second housing. 
         [0033]    In other embodiments, the thermoacoustic compressor further comprises a third housing having a first end, a second end, an inner wall, and an outer wall, the third housing defining a third cavity, the second end of the third housing operably connected to the first end of the first housing, and the second end of the third housing defining a third piston rod aperture, a second compression piston head having a first end, a second end, and an outer wall, the second compression piston head disposed in the third cavity, the first end of the second compression piston head and the first end of the third housing defining a fifth variable-volume chamber, and the second end of the second compression piston head and the second end of the third housing defining a sixth variable-volume chamber, a second piston rod having a first end and a second end, the first end of the second piston rod connected to the first end of the compression piston head, and the second end of the second piston rod connected to the second end of the second compression piston head, and a second valved intake port and a second valved discharge port on the first end of the third housing. In certain embodiments, the size of the third housing is the same or different from the size of the first housing. In further embodiments, the valved discharge post of the first housing is in fluid communication with the second valved intake port of the third housing. In such embodiments, the thermoacoustic compressor may further comprise an intercooler in fluid communication with the valved discharge port. 
         [0034]    The present disclosure also provides a multistage thermoacoustic compressor, comprising a first thermoacoustic compressor and a second thermoacoustic compressor, wherein the valved discharge port of the first thermoacoustic compressor is in fluid communication with the valved intake port of the second thermoacoustic compressor. In certain embodiments, the multistage thermoacoustic compressor further comprises an intercooler in fluid communication with the valved discharge port of the first thermoacoustic compressor. In particular embodiments the first thermoacoustic compressor is vertically aligned with the second thermoacoustic compressor, while in other embodiments the first thermoacoustic compressor is horizontally aligned with the second thermoacoustic compressor. 
         [0035]    The present disclosure further provides a thermoacoustic compressor comprising a first housing having a first end, a second end, an inner wall, and an outer wall, the first housing defining a first cavity, and the second end of the first housing defining a first piston rod aperture, a second housing having a first end, a second end, an inner wall, and an outer wall, the first end of the second housing operably connected to the second end of the first housing, the second housing comprising pressurized gas or fluid and defining a second cavity, and the first end of the second housing defining a second piston rod aperture, a third housing having a first end, a second end, an inner wall, and an outer wall, the second end of the third housing operably connected to the first end of the first housing, the third housing comprising pressurized gas or fluid and defining a third cavity, and the second end of the third housing defining a third piston rod aperture, a reciprocating piston axially movable within the first and second cavities, the reciprocating piston comprising, a compression piston head having a first end, a second end, and an outer wall, the compression piston head disposed in the first cavity, the first end of the compression piston head and the first end of the first housing defining a first variable-volume chamber, and the second end of the compression piston head and the second end of the first housing defining a second variable-volume chamber, a first piston rod having a first end and a second end, the first end of the first piston rod connected to the second end of the compression piston head, a first resonating piston head having a first end, a second end, and an outer wall, the first resonating piston head disposed in the second cavity, the first end of the first resonating piston head and the first end of the second housing defining a third variable-volume chamber, and the second end of the first resonating piston head and the second end of the second housing defining a fourth variable-volume chamber, the first end of the first resonating piston head connected to the second end of the first piston rod, a second piston rod having a first end and a second end, the second end of the second piston rod connected to the first end of the compression piston head, and a second resonating piston head having a first end, a second end, and an outer wall, the second resonating piston head disposed in the third cavity, the first end of the second resonating piston head and the first end of the third housing defining a fifth variable-volume chamber, and the second end of the second resonating piston head and the second end of the third housing defining a sixth variable-volume chamber, the second end of the second resonating piston head connected to the first end of the second piston rod, a first valved intake port and a first valved discharge port on the first end of the first housing, a first thermoacoustic engine connected to the inner wall of the second housing positioned between the second end of the first resonating piston head and the second end of the second housing, a second thermoacoustic engine connected to the inner wall of the third housing positioned between the first end of the second resonating piston head and the first end of the third housing, a means for inhibiting gas flow between the first and the second housing, a means for inhibiting gas flow between the first and the third housing, a means for providing or delivering heat to the first thermoacoustic engine, a means for providing or delivering heat to the second thermoacoustic engine, a means for removing heat from the first thermoacoustic engine, and a means for removing heat from the second thermoacoustic engine. In certain embodiments, the thermoacoustic compressor further comprises a second valved intake port and a second valved discharge port on the second end of the first housing. In other embodiments, the thermoacoustic compressor further comprises a starting mechanism connected to the first housing. 
         [0036]    The present disclosure additionally provides a method of compressing a fluid or gas, comprising, introducing a fluid or gas through the valved intake port of a thermoacoustic compressor into the first variable-volume chamber of the first cavity, and running the thermoacoustic compressor, thereby compressing the fluid or gas. In certain embodiments, the fluid or gas is filtered and/or refrigerated prior to introduction into the first variable-volume chamber. In particular embodiments, the compressed fluid or gas is released from the first variable-volume chamber through the valved discharge port. In further embodiments, the compressed fluid or air is stored after release from the first variable-volume chamber. In other embodiments, the compressed fluid or gas is cooled or heated after release through the valved discharge port. In yet other embodiments, the compressed fluid or gas is introduced into a compression chamber of a second thermoacoustic compressor. 
         [0037]    In additional embodiments, the compressed fluid or gas is introduced into a separate mechanical device, such as a gas turbine, an expander attached to an electrical generation system, an expander connected to a gas turbine power shaft, or a reciprocating engine. In further embodiments, heat is provided to the thermoacoustic engine from a separate mechanical device, for example waste heat generated by the separate mechanical device. In other embodiments, heat is provided to the thermoacoustic engine from a separate industrial process, for example waste heat generated by the separate industrial process. In particular embodiments heat is provided to the thermoacoustic engine from a separate alternative energy process, for example waste heat generated by the separate alternative energy process. 
         [0038]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention, as claimed. In this application, the use of the singular includes the plural, the word “a” or “an” may mean a singular object or element, or it may mean a plurality, at least one, or one or more of such objects or elements, and the use of “or” means “and/or”, unless specifically stated otherwise. Throughout this disclosure, unless the context dictates otherwise, the word “comprise” or variations such as “comprises” or “comprising,” is understood to mean “includes, but is not limited to” such that other elements that are not explicitly mentioned may also be included. Furthermore, the use of the term “including”, as well as other forms, such as “includes” and “included”, is not limiting. Also, terms such as “element” or “component” encompass both elements or components comprising one unit and elements or components that comprise more than one unit unless specifically stated otherwise. 
         [0039]    The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described and claimed. All documents, or portions of documents, cited in this application, including, but not limited to, patents, patent applications, articles, books, and treatises, are hereby expressly incorporated herein by reference in their entirety for any purpose. In the event that one or more of the incorporated literature and similar materials defines a term in a manner that contradicts the definition of that term in this application, this application controls. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]    The following drawings are included to further demonstrate certain aspects and embodiments of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein. 
           [0041]      FIG. 1 . A horizontal cross section through one embodiment of a single-acting non-lubricated thermoacoustic compressor. 
           [0042]      FIG. 2 . A horizontal cross section through one embodiment of a single-acting non-lubricated thermoacoustic compressor incorporating a means of return behind the compression piston head. 
           [0043]      FIG. 3 . A schematic of one embodiment of a thermoacoustic driven compressor/gas turbine system. 
           [0044]      FIG. 4A ,  FIG. 4B , and  FIG. 4C .  FIG. 4A . A horizontal cross section through one embodiment of a single-acting non-lubricated compression piston head.  FIG. 4B . A partial horizontal cross section through one embodiment of a single-acting non-lubricated compression piston head using a gas bearing system.  FIG. 4C . A horizontal cross section through one embodiment of a resonating piston head using a gas bearing system. 
           [0045]      FIG. 5 . A horizontal cross section through one embodiment of a single-acting lubricated thermoacoustic compressor. 
           [0046]      FIG. 6 . A horizontal cross section through one embodiment of a single-acting lubricated compression piston head. 
           [0047]      FIG. 7A  and  FIG. 7B .  FIG. 7A . A horizontal cross section through one embodiment of a double-acting non-lubricated thermoacoustic driven compressor incorporating a torus-derived thermoacoustic engine and tandem resonator at both ends of the compression piston head.  FIG. 7B . A horizontal cross section through one embodiment of a double-acting/single-acting non-lubricated/lubricated compression piston head. 
           [0048]      FIG. 8 . A horizontal cross section through one embodiment of a double-acting lubricated thermoacoustic driven compressor incorporating a cascaded thermoacoustic engine and a tandem resonator at both ends of the compression piston head. 
           [0049]      FIG. 9 . A horizontal cross section through a second embodiment of a double-acting lubricated thermoacoustic driven compressor incorporating a cascaded thermoacoustic engine and a tandem resonator at both ends of the compression piston head. 
           [0050]      FIG. 10 . Optional design of thermoacoustic end-housing with expanded compliance section. 
           [0051]      FIG. 11 . A horizontal cross section through one embodiment of a multistage thermoacoustic driven compressor incorporating a tandem compression head. 
           [0052]      FIG. 12A  and  FIG. 12B .  FIG. 12A . Schematic of a first horizontal orientation for single or multi-stage thermoacoustic compressors.  FIG. 12B . Schematic of a second horizontal orientation for single or multi-stage thermoacoustic compressors. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0053]    The present disclosure provides for a thermoacoustic driven compressor (“TADC”) that can utilize a heat driven standing or traveling wave thermoacoustic engine of any variation (e.g., requiring the use of a stack, regenerator, torus, hybrid (e.g., cascade), bellows, or any variation thereof), to power any type of reciprocating compressor or pump. A general discussion follows of exemplary TADCs containing three housings. These housings (thermoacoustic, distance, and compression) can have multiple mating surfaces and means of connecting mating surfaces to each other and/or to other structures. These housings can also be different sizes, vary in shape, and be separate from each other. It will be understood that the following discussion is not meant to be limiting, and that a TADC with greater or fewer housings or multiple components (from thermoacoustic, distance, compression, etc.) combined under one housing are within the scope of the present invention. It will also be understood that TADC housings can be formed from multiple components mated together. Finally, it will be understood that a TADC can be non-lubricated, lubricated, single-acting, double-acting, single-stage, multi-stage, and can incorporate tandem compression pistons and rods and/or a tandem resonating piston with accompanying piston rod and thermoacoustic engine(s). 
         [0054]    Referring to the figures,  FIG. 1  demonstrates one embodiment of a single-acting non-lubricated TADC  101  comprised of a thermoacoustic  102 , distance  110 , and compression  117  housing. The thermoacoustic housing (resonating tube)  102  contains a pressurized compressible working fluid/gas  126 . Supported inside the thermoacoustic housing  102  is a thermoacoustic engine core  103 , which in this embodiment includes a hot exchanger  104 , a cold exchanger  105 , and a stack  106 . When the hot exchanger  104  and cold exchanger  105  are connected to a hot source  128  and cold source  129 , respectively, a temperature differential is created between the two exchangers, and the stack  106  facilitates this process. This temperature gradient enables the thermoacoustic engine to generate an acoustic pressure wave  127  via the working fluid/gas medium  126 . Said another way, the pressurized working fluid/gas  126  expands and contracts within the stack  106 , moving heat from the hot exchanger  104  to the cold exchanger  105 . In so doing, the oscillating gas  126  exhibits standing wave time phasing characteristics  127 . This oscillating kinetic energy (e.g., an acoustic pressure wave) is converted to mechanical energy by means of a resonating piston head  107 , which can have seated sealing and/or guiding rings (not shown), reciprocates linearly, and is connected to a piston rod  108 . In embodiments where pressure/lubrication packing is not used (pressure/lubrication packing discussed in detail below), at locations where the piston rod  108  interacts with any of the housings lubricating strips  109  can be attached to the housing to reduce friction. 
         [0055]    The distance housing  110  contains a continuation of the linearly reciprocating piston rod  108 . As a means of controlling displacement, return, and centering of the piston assembly, one or more springs  111  can be incorporated in the distance housing  110 . The springs  111  can be mechanical (e.g., helix, double helix, or planar), gas, magnetic, or a combination thereof. Pressure packings  112  and  113 , or any other type of seal, can be set about the piston rod  108  and piston rod apertures  130  and  131  at both ends of the distance housing  110  to inhibit gas/fluid leakage from the thermoacoustic housing  102  and compression housing  117  via the piston rod  108 . For the side of the distance housing  110  facing the thermoacoustic housing  102 , a purging line  114  and canister  115  can be incorporated with pressure packing  112 . The canister  115  can contain the same gas as that in the thermoacoustic housing  102 , albeit at a higher pressure (gas used to expand rings in pressure packing, thereby providing a better seal) and can be attached to the exterior of the housing  110 . For the side of the distance housing  110  facing the compression housing  117 , a tube  116  may be attached to pressure packing  113  to vent residual compressed gas, although a purging line and canister could also be used (see  FIG. 2 ). 
         [0056]    The compression housing  117  contains the compression piston head  118 , piston sealing and/or guide rings (not shown), a cavity or compression chamber  119 , the remaining portion of the linearly reciprocating piston rod  108 , water jackets  120  and  121  (optional; could also use air fins together or separately (not shown)), gas/fluid inlet valve  122 , gas/fluid discharge valve  123 , gas/fluid inlet port  124 , and gas/fluid discharge port  125 . As the compression piston head  118  is interconnected by means of piston rod  108 , the oscillating acoustic force applied to the resonating piston head  107  propels the compression piston head  118  forward (to the right in  FIG. 1 ). As a result, the process gas/fluid in the compression chamber  119  is compressed. When the pressure in the compression chamber exceeds the discharge pressure, the process gas/fluid is released via the discharge valve  123 . On the return stroke, in this case due to springs  111 , the one-way inlet valve  122  opens so that new process gas/fluid can enter the compression chamber. 
         [0057]      FIG. 2  shows another embodiment of a single-acting non-lubricated TADC  201 . In this example, the thermoacoustic housing  202  (resonating tube) once again comprises a pressurized compressible working fluid/gas  226 , and incorporates a regenerator  206 , in lieu of a stack, in the thermoacoustic engine core  203 . Additionally, the thermoacoustic housing  202  is of a torus configuration that incorporates a compliance portion  228  and an inertance tube  229 . In traveling wave embodiments, the cold exchanger  205  is to the left of the hot exchanger  204  (with the cold exchanger  205  upstream of the regenerator  206 ). When the hot exchanger  204  and cold exchanger  205  are connected to a hot source  236  and cold source  235 , respectively, a temperature differential is created between the two exchangers. This temperature differential enables the regenerator  206  to amplify incoming acoustic power. This amplified acoustic power with traveling wave phasing  227  is then pumped out of the hot exchanger  204  and used to drive the linearly resonating piston head  207  (sealing and/or guiding rings not shown), which is connected to a piston rod  208 , and provide new acoustic power to the cold exchanger  205  via the inertance tube  229  and compliance portion  228 . One or more thermal buffer tubes (“TBT”)  230  can also be incorporated adjacent to the hot exchanger  204  at multiple locations, thereby mitigating heat leaks (and corresponding efficiency loss) from the hot exchanger to ambient. The regenerator  206  provides the same thermal isolation on the opposite side. 
         [0058]    The distance housing  210  contains a continuation of the linearly reciprocating piston rod  208 . Additionally, pressure packing  212 , with an accompanying purging canister  215  and a purging line  214 , can be set about the piston rod  208  and the distance housing piston rod aperture  237  facing the thermoacoustic housing, and pressure packing  213 , with an accompanying purging canister  231  and a purging line  216 , can be set about the piston rod  208  and the distance housing piston rod aperture  238  facing the compression housing. 
         [0059]    The compression housing  217  contains the compression piston head  218 , piston seals and/or guiding rings (not shown), a cavity or compression chamber  219 , the remaining portion of the linearly reciprocating piston rod  208 , water jackets  220  and  221  (optional), gas/fluid inlet valve  222 , gas/fluid discharge valve  223 , gas/fluid inlet port  224 , and gas/fluid discharge port  225 . A spring can be incorporated in the compression housing  217  as a means of controlling displacement, return, and centering of the compression piston head. This spring can be a balance chamber  232  (gas spring), which is located behind the compression piston  218 , one or more mechanical springs  233 , and a porting mechanism  234  (one-way valve optional—not shown), or any combination thereof. The gas spring  232  and mechanical spring  233  can be used to prevent the compression piston head  218  from contacting either end of the inner surface of the compression housing  217 . The porting mechanism  234  (e.g., a groove) allows the compression chamber  219  and balance chamber  232  to communicate during reciprocation of the compression piston head  218 , thereby further enabling the compression piston head  218  to stay centered. As the compression piston head  218  is interconnected by means of piston rod  208 , the oscillating acoustic force applied to the resonating piston head  207  propels the compression piston head  218  forward (to the right in  FIG. 2 ). As a result, the process gas/fluid in the compression chamber  219  is compressed. When the pressure in the compression chamber exceeds the discharge pressure, the process gas/fluid is released via the discharge valve  223 . On the return stroke, in this case due to springs  232  and  233 , the one-way inlet valve  222  opens so that new process gas/fluid can enter the compression chamber. 
         [0060]    While not shown in the above mentioned figures, a cascaded derived thermoacoustic engine or any variation/hybrid thereof could also be used to power a non-lubricated single acting TADC. Furthermore, all of the above mentioned compressors can incorporate a second set of valved inlet and discharge ports, thereby allowing process gas/fluid to be compressed on both the forward and backward motion of the piston (double-acting). 
         [0061]    The thermoacoustic housing can be fabricated from various materials including, but not limited to, ceramics, composites, aluminum, steel, cast steel, forged steel, stainless steel (e.g., 304, 316, 316H, 316L, 410, 419), carbon steel, alloys, including, but not limited to, nickel-based alloys (e.g., INCONEL® alloys), including, but not limited to, alloy 625, or any combinations thereof. While the resonating tube is cylindrical as shown, other shapes are possible, and the resonating tube can contain multiple sealable access holes. An oscillating side-branch (see, e.g., U.S. Pat. No. 6,560,970) may also be added to the thermoacoustic housing. 
         [0062]    The working fluid or gas can be selected from any number of known fluids or gases, including, but not limited to, inert gases, such as helium and argon. In general, the working fluid or gas should have a high speed of sound, high thermal conductivity, a low Prandtl number, and be non-flammable. 
         [0063]    In the thermoacoustic engine core, the hot exchanger and cold exchanger can take a variety of forms, including, but not limited to, shell-and-tube or finned-tube, or circulating heat exchanger design (see, e.g., U.S. Pat. No. 6,637,211), be in any order (in the case of a standing wave), have multiple units, and made from materials including, but not limited to, aluminum, aluminum alloy 6061, steel, cast steel, forged steel, stainless steel (e.g., 304, 316, 316H, 316L, 410, 419), carbon steel, alloys, including, but not limited to, nickel-based alloys (e.g., INCONEL® alloys), including, but not limited to, alloy 625, copper, oxygen-free high conductivity (“OFHC”) copper, tellurium copper, or any combination thereof. The stack and regenerator can also take a variety of forms, including, but not limited to, a honeycomb, stacked screen, parallel-plate, random fiber, foam, foil roll/stack, or packed spheres design, and can be made from materials including, but not limited to, aluminum, ceramic, composite, glass, metal hydrides, phase change materials, nanoparticles, carbon nanotubes, stainless steel (e.g., 304, 316, 316L, 316H, 410, and 419), carbon steel, and alloys, including, but not limited to, nickel-based alloys (e.g., INCONEL® alloys), including, but not limited to, alloy 625, or any combination thereof. 
         [0064]    Additional thermoacoustic housing components can include TBT, which can be made from materials including, but not limited to, aluminum, steel, cast steel, forged steel, stainless steel (e.g., 304, 316, 316L, 316H, 410, and 419), carbon steel, and alloys, including, but not limited to, nickel-based alloys (e.g., INCONEL® alloys), including, but not limited to, alloy 625, or any combination thereof. The length of the TBT should be greater than the peak-to-peak displacement of the gas at high amplitude, and the inside surface of the TBT can also be polished. The TBT can include at least one flow straightener and/or tapering, which mitigates Rayleigh streaming (see, e.g. U.S. Pat. No. 5,953,920). If an inertance tube is required, the inside surface can be polished, and a pressure balancing sliding joint can be included to reduce stress due to thermal expansion. A max flux suppressor (e.g., jet pump) can also be incorporated in the resonator to mitigate Gedeon streaming (see, e.g., U.S. Pat. No. 6,032,464). Further embodiments can include an additional ambient exchanger for residual heat leakage and multiple tori mated together in various ways. Iterations incorporating any single component (or different combinations) are also possible. 
         [0065]    The resonating piston can have various shapes, including, but not limited to, flat, truncated cone, cross-section of an isosceles trapezoid, concave, convex, or hemi-ellipses, can also have a variety of sizes, can be hollow, and can be made from the same materials as the thermoacoustic housing. Both the resonating piston and thermoacoustic housing cylinder liner can be coated with an anti-friction compound, such a thermoplastic polymer. While not shown in the above mentioned figures, sealing and/or guidance rings, which can also be coated with an anti-friction compound, can be seated in the resonating piston head. Rings can be any size, cut (e.g., angle, step, and butt), style (e.g., pressure balanced, single, and multi-segment), and made from any suitable composite plastic material (i.e. thermoplastic polymer), including, but not limited to, polytetrafluoroethylene (“PTFE”), polyetheretherketone (“PEEK”), and/or polyphenylene sulfide (“PPS”). The composite plastic material can also use fillers including, but not limited to, white glass, glass molybdenum (“glass moly”), glass graphite, carbon, PEEK, bronze, bronze molybdenum (“bronze moly”), PPS, molybdenum, and in any combination thereof. As an alternative to piston and/or guide rings, the resonating piston head/thermoacoustic housing could also incorporate a gas/fluid bearing, which can be of a design including, but not limited to, hydrostatic, hydrodynamic, or any combination thereof (discussed below). Replaceable cylinder liners can also be used with the resonating and/or compression piston head. While not shown, a means of piston displacement control and return, which can include, but is not limited to, one or more springs (gas, mechanical, or any combination thereof), can set between the resonating piston and the piston rod aperture (or any other location in the thermoacoustic housing); a valved porting means may also be incorporated. 
         [0066]    Pressure packing, lubrication wiper packing, or any other type of seal, can be set around the piston rod where the rod penetrates the thermoacoustic housing, compression housing, and/or distance housing (or in any other location). The packing can also abut or penetrate the apposing housing. A purging canister, which can contain the same gas as that in the thermoacoustic housing, purging line, and/or venting tube can also be included. The pressure packing can be of the water-cooled or non-water-cooled variety (e.g., Thermosleeve™). 
         [0067]    The compression housing, piston, piston rod, and distance housing can be made from materials including, but not limited to, ceramic, iron, cast iron, nodular cast iron, ductile iron, gray iron, aluminum, steel, cast steel, forged steel, stainless steel (e.g., 304, 316, 316L, 316H, 410, and 419), carbon steel, bronze, and alloys, including, but not limited to, nickel-based alloys (e.g., INCONEL® alloys), including, but not limited to, alloy 625, or any combination thereof. Just as with the resonating piston head, the compression piston head, piston rings, guide rings, and/or compression housing cylinder liner may be coated with an anti-friction compound, such as a thermoplastic polymer. Furthermore, the compression piston can be hollow, and use gas bearings of any variation. The distance and compression housing may also have multiple sealable access holes and a means of piston displacement control and return, which can include, but is not limited to, one or more springs (gas, mechanical, or any combination thereof) in multiple housings. Additionally, all of these components and others, such as replaceable cylinder liners, inlet/discharge valves, which can be corrosion resistant (e.g., stainless steel, engineered plastics) and of reed, one-way check, channel, concentric ring, ported plate, or poppet valve design, are all commercially available. Finally, all mating surfaces for thermoacoustic, distance, and compression housings not only provide first, second (via packing/strips), or no support to the piston rod, but can also provide means for guiding the reciprocating rod linearly and inhibiting radial movement. 
         [0068]      FIG. 3  schematically illustrates one embodiment of a TADC  300  interfaced with a gas turbine  301 . In this embodiment, the gas turbine  301  has two shafts (mechanical drive). The first shaft assembly  302  of the gas turbine  301  includes a compressor  303  (intercooler not shown), a combustor  304 , and a high pressure (“HP”) turbine  305  (first part of two part expander). A power turbine  306  (second expander) is attached to the second shaft  307 . This turbine  306  drives a mechanical device  308 , which in this embodiment is a centrifugal compressor, such as for a gas pipeline. Other mechanical devices (on or offshore) include, but are not limited to, an electric generator or a pump (not shown). 
         [0069]    To initiate the process, air is compressed in the compressor  303 . The compressed air is then piped via flow path  309  to the combustor  304 , where the air is mixed with fuel and ignited. The expanding gas drives both the HP turbine  305  and the power turbine  306 . Exhaust heat exiting the gas turbine can be channeled via flow path  310  and optional valve  311  into a heat recovery unit (“HRU”)  312 . Concurrently, circulating fluid (via optional pump  313 ) can be pumped via flow path  314  into the HRU. The circulating fluid is heated via the exhaust and then piped via flow path  315  into the hot exchanger of the TADC  300 . While not shown, cold fluid can also delivered (pump optional) into the cold exchanger of the TADC  300 , and an additional exchanger and fan may also be included for cooling the cold fluid with ambient air. 
         [0070]    The temperature gradient between the hot and cold exchangers of the TADC  300  powers the TADC  300 . As a result, air is sucked through filter  316  and refrigeration unit  317  (optional) and compressed in TADC  300 . The “free compressed air” is then channeled to a pulsation bottle  318 , where the air flow is evened out. The compressed air can then be piped via flow path  319  to the HRU  312 , where the air is further heated. At this point, the air can be directed via valves  320 ,  321 ,  322  and  323  to any stage, in any quantity, at any pressure, and at multiple locations in the gas turbine  301 , specifically a point before the combustor  304  but after the turbine compressor  303 , for example, prior to the NOx equipment (valve  320 ), the combustor  304 , the HP turbine  305  (valves  321  and  322 ), and between the HP turbine exhaust outlet and power turbine inlet (valves  321  and  323 ). While not shown, other points include the turbine compressor  303 , after the combustor  304  but before the HP turbine  305 , the power turbine  306 , a recuperator (if used) or some combination thereof. If a single shaft is used (not shown), air can also be directed to some point after the combustor, but before the turbine, and the turbine. The “free compressed air” improves the efficiency of the gas turbine  301  over various loads, as the work used to create the “free compressed air” was not obtained from the compressor  303  of the gas turbine  301 . Said another way, the TADC  300  reduces the amount of CO 2  emitted per a given unit of energy produced from a gas turbine, allowing companies the potential to earn carbon credits in a carbon regulated environment. In addition, the TADC  300  allows for the use of heat that otherwise would be vented and lost from the gas turbine  301 . The use of the TADC  300  thus means that the efficiency of the compressor  303  may be increased, thereby reducing the amount of natural gas needed for the compressor  303  in a gas pipeline. This results in lower costs for the operator of a gas pipeline using a TADC  300  with the compressor  303 . 
         [0071]      FIG. 4A  provides detail for a variation of a single-acting non-lubricated compression piston head  118 B for TADC  101  shown in  FIG. 1 . This compression piston head  118 B contains a sealing ring  130  seated in a groove  131  in compression piston head  118 B and coaxial with the axis of the piston and cavity side wall, thereby preventing compressed gas/fluid from leaking from the compression chamber  119  between the compression piston head  118 B and the inner surface of the compression housing  117 . A biasing means  132  of forcing the sealing ring  130  to stay in contact with the inner surface of the compression housing  117  can also be included, if such a device is not incorporated in sealing ring  130 . To prevent the piston from coming into contact with the inner surface of the compression housing  117 , at least one seated guide ring  133  (e.g., a rider ring) can be utilized, which is seated in a second groove  134  in the compression piston head  118 B. As with the sealing ring  130 , the guide ring  133  is coaxial with the axis of the compression piston head  118 B and the inner surface of the compression housing  117 . 
         [0072]      FIG. 4B  demonstrates one embodiment of a single-acting non-lubricated compression piston head  118 C utilizing a hydrostatic gas/fluid bearing with TADC  101  shown in  FIG. 1 . The basic operating characteristics are the same as those mentioned earlier. However, as compression piston head  118 C moves forward (to the right in  FIG. 1 ), some of the pressurized process gas/fluid (e.g., air) in the compression chamber  119  is delivered to a clearance gap between the outer wall of compression piston head  118 C and the inner wall of compression housing  117 , thereby providing a gas bearing. The delivery system can include, but is not limited to, at least a first aperture  135 , a passageway  136 , a second aperture  137 , a circumferential groove  138 , which is set about the outer wall of compression piston head  118 C, or some combination thereof. While not shown, another example could have multiple branches originating from passageway  136  to additional apertures in fluid communication with circumferential groove  138 . In yet another embodiment, the compression piston incorporates a one-way valve with the first aperture  135 , a reservoir, and multiple apertures in the compression piston head at angularly spaced locations around the circumference of the sliding compression piston, all of which are in fluid communication with the reservoir; however, in this case no circumferential groove is required (see, e.g., U.S. Pat. No. 5,525,845). The gas bearing in  FIG. 4B  can also be used with a double-acting piston (not shown) as described above (or in any other single/double-acting iteration described below; not shown); however, at least a second set of apertures (not shown), another passageway (not shown), and a second circumferential groove (not shown) delivering gas/fluid (not shown) from the opposite compression chamber (not shown) would be required (see, e.g., U.S. Pat. No. 4,932,313). Conversely, pressurized gas/fluid from the compression housing  117  can be delivered to the clearance gap via a system that is part of the compression housing (discussed in greater detail in  FIG. 4C ). In this example, at least one radial aperture (entrance; not shown) and at least three radial apertures (exit; not shown) would be required. Furthermore, the three radial apertures (not shown) would be formed in the compression housing  117  at angularly spaced locations around the circumference of the sliding compression piston head  118 C (multiple sets are also possible). Connecting the entrance and exit apertures (not shown) is at least one passageway (not shown), which can be within, on top of, or in-between separate compression housings. This alternative could also use at least one one-way valve (not shown), a reservoir (not shown), and compressed gas/fluid (not shown) from an external source (not shown), such as a tank, a gas turbine bleed line, an on-site electrical compressor, a turbine-driven centrifugal compressor, a reciprocating compressor, a rotary compressor, a screw compressor, or other type of compression equipment/plant processes. 
         [0073]      FIG. 4C  provides detail to one embodiment of a resonating piston head for TADC  101  shown in  FIG. 1  further including hydrostatic gas/fluid bearings. As shown in  FIG. 4C , the pressurized working gas/fluid is drawn from the variable-volume chamber  139  to the right of the resonating piston head  107 ; however, the pressurized fluid could also be drawn from the opposing variable-volume chamber  140 , or both. As the resonating piston head  107  moves to the right, the working gas/fluid in the variable-volume chamber  139  increases in pressure; this increase in pressure forces some of the gas/fluid through the aperture  141  and one-way valve  142  into reservoir  143 . Seeking areas of lower pressure, the pressurized fluid in the reservoir  143  is dispersed via passageway(s)  144  and at least three radial apertures (exit)  145  in the thermoacoustic housing  102 . The radial apertures  145  can be formed at angularly spaced locations around the circumference of the sliding resonating piston head  107 . Furthermore, multiple sets of radial apertures  145  in fluid communication with passageway(s)  144  are also possible. As the pressurized fluid is released from the radial apertures  145 , it is directed to a clearance gap in-between outer wall of resonating piston head  107  and inner wall of thermoacoustic housing  102 , thereby providing a gas bearing. In this example the reservoir  143  and passageway(s)  144  are located within the thermoacoustic housing cylinder wall; however, other iterations can have these components within, on top of, or in-between separate compression housings (see, e.g., U.S. Pat. No. 6,293,184). In another embodiment, the one-way valve  142  and/or reservoir  143  may not be required. Furthermore, the pressurized fluid can be delivered to the clearance gap from both variable-volume chambers sequentially. A hydrostatic gas bearing may include, but is not limited to, any component discussed above, use a separate dedicated pump, and an aperture further consisting of orifices and/or porous media (e.g., carbon, bronze or steel), or some combination thereof. Finally, any gas bearing design as described in  FIG. 4B  and  FIG. 4C  can be used with any resonator piston head, even if resonator is attached to a lubricated compression piston head. 
         [0074]      FIG. 5  shows an embodiment of a single-acting lubricated standing wave TADC  500 . This TADC is similar to the TADC shown in  FIG. 1 , except that the compression housing  501  differs from that shown in  FIG. 1 . Compression housing  501  contains compression piston head  502 , which is lubricated by a pressurized lubricating system  503 . In this embodiment, pressurized lubricating system  503  comprises pump  504 , lubricant line  505 , and lubricant recovery line  506 . In addition to a compression chamber  507 , compression housing  501  defines a cavity  508  for collecting lubricant, where it feeds into lubricant recovery line  506 . While not shown, a pressurized lubricating system can also include items such as a lubricant filter, a lubricant dispenser, and a spray nozzle. Finally, lubricant wiper packing may be substituted for pressure packing. 
         [0075]      FIG. 6  shows a variation of a single-acting lubricated compression piston head  600  for use with the lubricated TADC  500  shown in  FIG. 5 . To remove lubricant from the cavity wall, the compression piston head  600  utilizes a scraper ring  601 . The scraper ring can be made from metal (e.g., cast iron or aluminum) or metal alloy. Scraper ring  601  channels lubricant into a port  602 , which directs the lubricant to the portion of the compression housing ( 501  in  FIG. 5 ) comprising a cavity ( 508  in  FIG. 5 ) for collecting the lubricant. As with the non-lubricated piston head, the lubricated compression piston head  600  also comprises a sealing ring  603  seated in a groove  604  in compression piston head  600  and coaxial with the axis of the compression piston head  600  and the inner surface of the compression housing ( 501  in  FIG. 5 ), thereby preventing compressed gas/fluid from leaking from the compression chamber ( 507  in  FIG. 5 ) between the compression piston head  600  and the inner surface of the compression housing ( 501  in  FIG. 5 ). A biasing means  605  for forcing the sealing ring  603  to stay in contact with the inner surface of the compression housing ( 501  in  FIG. 5 ) can also be included, if such a device is not incorporated in sealing ring  603 . To prevent the compression piston head  600  from coming into contact with the inner surface of the compression housing ( 501  in  FIG. 5 ), at least one seated guide ring  606  can be utilized, which is seated in a second groove  607  in the compression piston head  600 . As with the sealing ring  603 , the guide ring  606  is coaxial with the axis of the compression piston head  600  and the inner surface of the compression housing ( 501  in  FIG. 5 ). 
         [0076]    The TADC  500  shown in  FIG. 5  utilizes lubricant in a closed loop system, and as a result, very little lubricant seeps into the compressed fluid or gas stream. However, a single or double-acting TADC  500  of any variation can utilize “once through” lubrication, wherein new lubricant is continuously force-fed into the compression chamber. In such embodiments, a scraper ring and cavity are not required. In “once through” lubrication, the lubricant lubricates the compression piston head and exits through the exhaust port with the compressed process gas/fluid. Upon exit, a means, such as a coalescer, can be used to separate the lubricant from the compressed processed gas/fluid. 
         [0077]    As mentioned above, for control of piston displacement and return, a spring (gas (like spring  232  in  FIG. 2 ), mechanical (like spring  111  in  FIG. 1 ), or combination thereof) can be used in any or multiple housings. However, if a spring(s) is deemed not sufficient, as described below an additional thermoacoustic engine (housing and engine core), as described herein, can be attached to the top of the single- or double-acting TADC compression housing (see, e.g.,  FIG. 7 ). Also, a distance housing (like housing  728  in  FIG. 7 ), as described herein, can separate the compression housing from the second thermoacoustic engine. Inside the additional housing(s), a tandem rod and resonating piston combination is mated to the top of the single-acting or double-acting compression piston (see, e.g.,  FIG. 7 ). In essence, a second thermoacoustic engine is utilized, can be in conjunction with a spring(s) (gas, mechanical, or combination thereof) in any or multiple housings, to force the piston back. A porting means can also be included (not shown). 
         [0078]      FIG. 7A  shows one embodiment of a double-acting non-lubricating traveling wave TADC  700  with two thermoacoustic housings  701  and  702 , each of which comprise a pressurized compressible working gas/fluid  703  and  704 . Thermoacoustic housings  701  and  702  each incorporate a regenerator  705  and  706  in the thermoacoustic engine core  707  and  708 . While not shown, one or more TBTs can also be incorporated adjacent to the hot exchanger, thereby mitigating heat leaks (and corresponding efficiency loss) from the hot exchanger to ambient. Additionally, the thermoacoustic housings  701  and  702  are of a torus configuration that incorporate a compliance portion  709  and  710  and an inertance tube  711  and  712 . In the depicted traveling wave embodiment, the cold exchangers  713  and  714  are upstream of the hot exchangers  715  and  716 . When the hot exchangers  715  and  716  and cold exchangers  713  and  714  are connected to hot sources  717  and  718  and cold sources  719  and  720 , respectively, a temperature differential is created between the two exchangers. This temperature differential enables the regenerators  705  and  706  to amplify incoming acoustic power (not visibly shown, but represented by  721  and  722 ) and pump acoustic power out of the hot exchangers  715  and  716 . This acoustic power is used to drive the linearly resonating piston heads  723  and  724 , which are connected to piston rods  725  and  726 , and provide new acoustic power to the cold exchangers  713  and  714  via the inertance tubes  711  and  712  and compliance portions  709  and  710 . 
         [0079]    The distance housings  727  and  728  contain a continuation of the linearly reciprocating piston rods  725  and  726 . Additionally, pressure packings  729  and  730 , each with an accompanying purging canister  731  and  732  and a purging line  733  and  734 , can be set about the piston rods  725  and  726  and the piston rod apertures  754 ,  755 ,  756 , and  757 , in the distance housings  727  and  728 , and pressure packings  735  and  736 , each with an accompanying vent tube  737  and  738 , can be set about the piston rods  725  and  726  and the piston rod apertures in the distance housings  727  and  728 . 
         [0080]    Compression housing  739  incorporates a double-acting compression piston head  740 . The compression housing  739  and double-acting compression piston head  740  define two compression chambers  741  and  742 . Compression housing  739  also comprises the remaining portion of piston rods  725  and  726 , sealing and/or guide rings (discussed below), water jackets  743  and  744 , gas/fluid inlet valves  745  and  746 , gas/fluid discharge valves  747  and  748 , gas/fluid inlet ports  749  and  750 , and gas/fluid discharge ports  751  and  752 . 
         [0081]    To start TADC  700 , a starting mechanism  753  can be used to propel compression piston head  740  forward (to the right in  FIG. 7A ). As a result, the process gas/fluid in compression chamber  742  is compressed. When the pressure in the compression chamber exceeds the discharge pressure, the process gas/fluid is released via the discharge valve  748 . This also opens inlet valve  745  so that process gas/fluid can enter compression chamber  741 . On the return stroke, powered by the temperature differential created in thermoacoustic engine core  708 , traveling acoustic wave  722  propels linear resonating piston head  724  (to the left in  FIG. 7A ). As the compression piston head  740  is connected to piston rod  726 , the force applied to the resonating piston head  724  propels the compression piston head  740  forward (to the left in  FIG. 7A ). As a result, the process gas/fluid in compression chamber  741  is compressed. When the pressure in the compression chamber exceeds the discharge pressure, the process gas/fluid is released via the discharge valve  747 . This also opens inlet valve  746  so that new gas/fluid can enter compression chamber  742 . It is also to be understood that if piston head  740  has difficulty initially moving forward (to the right in  FIG. 7A ), discharge valve  748  can be configured to open sooner, thereby reducing the load on compression piston head  740 . Similarly, on the return stroke, discharge valve  747  can also be configured to open sooner. 
         [0082]    The starting mechanism  753  for TADC  700  (and  800  and  900  discussed below) can take a variety of different forms. For example, compressed air could be injected into one or both (in alternating sequence) sides of the compression piston head  740  via a separate delivery system or the valved inlet ports  749  and  750 . Compressed air could also be applied to an expansion unit (not shown) in one or both of the distance pieces  727  and  728 . The sources for the compressed air could include an air tank, a gas turbine bleed line, an on-site electrical compressor, a turbine-driven centrifugal compressor, a reciprocating compressor, a rotary compressor, a screw compressor, or other type of compression equipment/plant processes (not shown). Additionally, compressed working fluid could be injected into one or both thermoacoustic housings  701  and  702  between the resonating piston head  723  and  724  and housing  701  and  702  (via a purging canister, not shown). Another means of starting oscillation would be to insert a magnet (not shown) in the compression piston head  740  and a coil at both ends of the compression housing  739 , and alternate electric voltage between both ends. 
         [0083]      FIG. 7B  shows one variation of a double-acting non-lubricated/lubricated compression piston head  760 , which could be used with TADC  700  or any other double-acting TADC. In this embodiment, two seated sealing rings  761  and  762  are located at the center of compression piston head  760 , while at least two guiding rings  763  and  764  are located on opposite sides of the sealing rings  761  and  762 . A means (not shown) of forcing the sealing rings  761  and  762  to stay in contact with the inner surface of the compression housing  739  can also be included, if such a device is not incorporated in the sealing rings  761  and  762 . Another option includes incorporating at least one sealing ring at both ends (not shown) of the compression piston head  740 , and a means of forcing the sealing rings to stay in contact with the inner surface of the compression housing  739 . 
         [0084]      FIG. 8  provides one embodiment of a double-acting lubricated cascaded TADC  800 . In this embodiment, thermoacoustic housings  801  and  802  can each be approximately 1 acoustic wavelength long (the same length as the wavelength of the acoustic wave) and contain pressurized compressible working fluid. Furthermore, both thermoacoustic housings  801  and  802  comprise at least one stack-based thermoacoustic engine core ( 803  and  804 , respectively), which is used to initiate an acoustic pressure wave (not visible, but represented by  805  and  806 , respectively) and at least one regenerator-based thermoacoustic engine core ( 817  and  818 , respectively). Each stack-based thermoacoustic engine core ( 803  and  804 ) comprises a hot exchanger ( 807  and  808 , respectively) connected to a hot source ( 809  and  810 , respectively) and a cold exchanger ( 811  and  812 , respectively) connected to a cold source ( 813  and  814 , respectively). Stacks ( 815  and  816 , respectively) are located between the hot exchangers ( 807  and  808 , respectively) and the cold exchangers ( 811  and  812 , respectively). Separating the stack-based engines  803  and  804  from the regenerator-based thermoacoustic engines ( 817  and  818 , respectively) can be TBTs ( 819  and  820 , respectively), which mitigate heat leakage between the stack-based and regenerator-based thermoacoustic engines. Each regenerator-based thermoacoustic engine core ( 817  and  818 ) comprises a hot exchanger ( 821  and  822 , respectively) connected to a hot source ( 823  and  824 , respectively) and a cold exchanger ( 825  and  826 , respectively) connected to a cold source ( 827  and  828 , respectively). Regenerators ( 829  and  830 , respectively) are located between the hot exchangers ( 821  and  822 , respectively) and the cold exchangers ( 825  and  826 , respectively). Also shown in thermoacoustic housing  801  is an optional ambient exchanger  831  (can be used in both housings). Regenerators  829  and  830  amplify the acoustic power (not visible, but represented by  832  and  833 , respectively) created by stack-based engines  803  and  804 . This acoustic power is used to drive the linearly resonating piston heads  834  and  835 , which are connected to piston rods  836  and  837 . 
         [0085]    The distance housings  838  and  839  contain a continuation of the linearly reciprocating piston rods  836  and  837 . Additionally, pressure packings  840  and  841 , each with an accompanying purging canister  842  and  843  and a purging line  844  and  845 , can be set about the piston rods  836  and  837  and the piston rod apertures  864 ,  865 ,  866 , and  867 , of the distance housings  838  and  839 , and pressure/lubricating packings  846  and  847 , each with an accompanying vent tube  848  and  849 , can be set about the piston rods  836  and  837  and the piston rod apertures of the distance housings  838  and  839 . 
         [0086]    Compression housing  850  incorporates a double-acting compression piston head  851 . The compression housing  850  and double-acting compression piston head  851  define two compression chambers  852  and  853 . Compression housing  850  also comprises the remaining portion of piston rods  836  and  837 , sealing and guide rings (discussed above), gas/fluid inlet valves  854  and  855  and gas/fluid discharge valves  856  and  857 , and gas/fluid inlet ports  858  and  859  and gas/fluid discharge ports  860  and  861 . Compression housing  850  also comprises lubricating system  862  comprising pump  863  and lubricant line  869  (lubricant dispenser and filter not shown). 
         [0087]    To start TADC  800 , a starting mechanism  868  can be used to propel compression piston head  851  forward (to the right in  FIG. 8 ). As a result, the gas/fluid in compression chamber  853  is compressed. When the pressure in the compression chamber exceeds the discharge pressure, the process gas/fluid is released via the discharge valve  857 . This also opens inlet valve  854  so that process gas/fluid can enter compression chamber  852 . On the return stroke, the amplified traveling acoustic wave  833  propels linear resonating piston head  835  (to the left in  FIG. 8 ). As the compression piston head  851  is connected to piston rod  837 , the force applied to the resonating piston head  835  propels the compression piston head  851  forward (to the left in  FIG. 8 ). As a result, the process gas/fluid in compression chamber  852  is compressed. When the pressure in the compression chamber exceeds the discharge pressure, the process gas/fluid is released via the discharge valve  856 . This also opens inlet valve  855  so that new process gas/fluid can enter compression chamber  853 . It is also to be understood that if piston head  851  has difficulty initially moving forward (to the right in  FIG. 8 ), discharge valve  857  can be configured to open sooner, thereby reducing the load on compression piston head  851 . Similarly, on the return stroke, discharge valve  856  can also be configured to open sooner. 
         [0088]      FIG. 9  demonstrates another embodiment of a double-acting lubricated cascaded TADC  900 . TADC  900  is similar to TADC  800  shown in  FIG. 8 , except that the thermoacoustic housings  901  and  902  and distance housings  903  and  904  differ from those shown in  FIG. 8  (thermoacoustic housings  801  and  802 , and distance housings  838  and  839 ). Thermoacoustic housings  901  and  902  each comprise two different cross-sectional areas ( 905  and  906 , and  907  and  908 , respectively) with each cross sectional area having a length of approximately ¼ acoustic wavelength. The portion of the thermoacoustic housings with the smaller cross-sectional area ( 905  and  907 , respectively) can comprise a stack-based thermoacoustic engine core ( 909  and  910 , respectively), and the portion of the thermoacoustic housings with the larger cross-sectional area ( 906  and  908 , respectively) can comprise a regenerator-based thermoacoustic engine core ( 911  and  912 , respectively). As detailed in  FIG. 8 , above, the stack-based thermoacoustic engine cores  909  and  910  are used to initiate an acoustic pressure wave (not visible, but represented by  943  and  944 , respectively). Each stack-based thermoacoustic engine core ( 909  and  910 ) comprises a hot exchanger ( 913  and  914 , respectively) connected to a hot source ( 915  and  916 , respectively) and a cold exchanger ( 917  and  918 , respectively) connected to a cold source ( 919  and  920 , respectively). Stacks ( 921  and  922 , respectively) are located between the hot exchangers ( 913  and  914 , respectively) and the cold exchangers ( 917  and  918 , respectively). Separating the stack-based engine cores  909  and  910  from the regenerator-based thermoacoustic engine cores ( 911  and  912 , respectively) can be TBTs ( 923  and  924 , respectively), which mitigate heat leakage between the stack-based and regenerator-based thermoacoustic engine cores. Each regenerator-based thermoacoustic engine core ( 911  and  912 ) comprises a hot exchanger ( 925  and  926 , respectively) connected to a hot source ( 927  and  928 , respectively) and a cold exchanger ( 929  and  930 , respectively) connected to a cold source ( 931  and  932 , respectively). Regenerators ( 933  and  934 , respectively) are located between the hot exchangers ( 925  and  926 , respectively) and the cold exchangers ( 929  and  930 , respectively). Regenerators  933  and  934  amplify the acoustic power (not visible, but represented by  935  and  936 , respectively) created by stack-based engines  909  and  910 . This acoustic power is used to drive the linearly resonating piston heads  937  and  938 , which are connected to piston rods  939  and  940 . Distance housings  903  and  904  differ from those shown in  FIG. 8  ( 838  and  839 ) by the inclusion of a mechanical spring ( 941  and  942 , respectively). This spring can also be gas, or combination thereof, and can also be present in multiple locations in the distance, thermoacoustic, and compression housings. A porting means, which can be valved, could also be incorporated. 
         [0089]    Cascaded thermoacoustic engines (engines and housings) of any variation (see, e.g., U.S. Pat. No. 6,658,862) can be used to power both resonating piston heads  937  and  938 . With the cascade design, a stack-derived thermoacoustic engine core can be used to initiate the acoustic pressure wave, and exchangers can be arranged in any order. A regenerator-derived engine core is used to amplify the acoustic power generated from the stack. In certain embodiments, the TBT can actually connect the stack-based thermoacoustic engine core and the regenerator-based thermoacoustic engine core. In general, the TBT is at least as long as the peak-to-peak displacement of the gas/fluid and can also be tapered (see, e.g., U.S. Pat. No. 5,953,920). For additional power, one or more stacks, regenerators, or TBTs in any combination can be added in series, and a bellows can be added to accommodate thermal expansion and contraction of the various components. Flow straighteners and additional ambient exchangers may also be added. If heat leaks are excessive, a second housing can encase the thermoacoustic housing. The thermoacoustic housing (resonating tube) can extend beyond the second housing, although this generally requires the use of seals. The second housing can be pressurized to a similar pressure as that of the thermoacoustic housing, and can also contain insulation. 
         [0090]    The stacks and regenerators within the thermoacoustic housings should generally be placed in a region of the acoustic wave of high specific acoustic impedance. It is also possible to have multiple regions of high specific acoustic impedance along an axis in the thermoacoustic housing (e.g., a housing that is 1 acoustic wavelength long). In such a case, each region could contain adjacent multiple stacks, TBTs, and/or regenerators (which could be connected) in series and in any combination thereof. A means of creating multiple regions of high specific acoustic impedance would be to insert an approximately ½ acoustic wavelength resonator of different cross-sectional area between the approximately ¼ acoustic wavelength resonators as shown in  FIG. 9  (indefinite ½ acoustic wavelength extensions, and other extension lengths, are possible). Additionally, between at least two regions of high specific acoustic impedance a side branch and bulb combination, which is generally orthogonal to the axis of the resonator, can also be added to the thermoacoustic housing, thereby providing axially extended regions with high specific acoustic impedance (see, e.g., U.S. Pat. No. 6,658,862). Finally, this extended region can be further extended by periodically adding additional side branch and bulb combinations. For additional balance, these side branches can be on both sides of the resonator at the same axial location. 
         [0091]      FIG. 10  describes an optional design of a thermoacoustic end-housing  1000  with an expanded compliance section  1001  (see, e.g., U.S. Pat. No. 6,658,862), which can be used with an embodiment of a TADC  900  as shown in  FIG. 9 . The circumference of the piping  1002  may expand as it approaches and penetrates into the expanded compliance section  1001 , thereby lowering the velocity of the gas coming from the compliance section  1003 . 
         [0092]    For multistage compression, multiple TADCs of any variation can be mated together in any orientation. Piping, with inter-cooling and optional coalescer/scrubber, connects the discharge ports to the inlet ports, allowing for the transmission of compressed air. If desired, a refrigerator (including thermoacoustic and Sterling refrigerators) or a desiccant dryer can also be incorporated to dehumidify the air after compression. 
         [0093]    As described in one embodiment in  FIG. 11 , another means of creating multistage compression (or additional capacity) comprises mating a second compression housing to the compression housing of a single or double-acting TADC with one thermoacoustic engine; a second distance piece, accompanying pressure packing, purging canister, purging line, and/or vent tube, as described herein, can also be included. Inside, a tandem single or double-acting compression piston head and piston rod would be mated to the master piston of the TADC. Such embodiments are not limited to one additional compression housing and distance piece, and depending on need (multistage or capacity), tandem compression piston can vary in size. Also, if the tandem compression piston is double-acting, the second compression chamber would have more than one vented inlet and outlet port. 
         [0094]      FIG. 11  describes one embodiment of a tandem single-acting non-lubricated TADC  1100  with one thermoacoustic engine (not shown). This embodiment incorporates a first compression housing  1101  and a second compression housing  1102 . First compression housing  1101  comprises a first compression piston head  1103 , which is attached to a first piston rod  1104  and a second piston rod  1105 . First compression housing  1101  and first compression piston head  1103  define a first compression chamber  1106 . First compression housing  1101  also comprises piston and guide rings (not shown), water jackets  1107  and  1108  (optional), gas/fluid inlet valve  1109 , gas/fluid discharge valve  1110 , gas/fluid inlet port  1111 , and gas/fluid discharge port  1112 . Second compression housing  1102  comprises a second compression piston head  1113 , which is attached to the top end of the first compression piston head  1103  via the second piston rod  1105 . The second compression housing  1102  and second compression piston head  1113  define a second compression chamber  1114 . Second compression housing  1102  also comprises piston and guide rings (not shown), water jackets  1115  and  1116 , gas/fluid inlet valve  1117 , gas/fluid discharge valve  1118 , gas/fluid inlet port  1119 , and gas/fluid discharge port  1120 . Second compression housing  1102  also comprises pressure packing  1121 , with an accompanying purging canister  1122  and a purging line  1123  set about the second piston rod  1105  and the mating surface of the first compression housing  1101 ; while not shown, a vent tube may be used in lieu of a purging canister and purging line. In this embodiment, as with the other types of multistage compression, the gas/fluid discharge port  1112  of the first compression housing  1101  can be connected via piping  1124  to the gas/fluid intake port  1119  of the second compressor housing  1102 . In other embodiments, inter-cooling, lubrication, scrubbers, dehumidification, and coalescers (not shown) can also be utilized. 
         [0095]    The TADC as discussed in  FIG. 7A , as well as other embodiments (e.g.,  FIG. 8 , and  FIG. 9 ), could also be further expanded to generate multistage compression (or additional capacity). In this case (not shown), as described herein, at least one additional compression housing, compression piston (piston size and housing will vary depending on purpose), piston rod, pressure/lubrication wiper packing with either purging canister and line or venting tube, and distance housing (optional) could be inserted between the compression housing and the second thermoacoustic housing or distance housing. Inter-cooling, coalescers, dehumidification, and scrubbers (not shown) can also be utilized. 
         [0096]    A means (not shown) of condensing process gas/fluid (e.g., air), such as refrigeration (which can be thermoacoustic or Sterling refrigeration), can also be attached to the inlet port of a single or multistage TADC of any variation, thereby allowing greater volumes of process gas/fluid to be compressed. Filter(s) (not shown) can also be added to the inlet port to clean the process gas/fluid. Pulsation tubes (not shown) can also be used to even out the flow of processed gas/fluid from the TADC; the pulsation tubes can be directly attached to TADC. The compressed gas/fluid can also be stored (not shown) before use and a Heat Recovery Unit (HRU)/exchanger or similar device (not shown) can be used to heat the compressed gas/fluid before use. Finally, valves (not shown) can be used in any location for controlling flow of process gas/fluids. 
         [0097]      FIG. 12A  and  FIG. 12B  schematically demonstrate two orientations for coupling TADCs of any variation, horizontally apposed  1201  ( FIG. 12A ) and horizontally aligned  1202  ( FIG. 12B ). When multistage compression is desired in the orientation shown in  FIG. 12A , the gas discharge port  1204  of the first TADC  1203  can be connected via flow path  1205  to intercooler  1206 , and via flow path  1207  to the gas intake port  1208  of the second TADC  1209 . When multistage compression is desired in the orientation shown in  FIG. 12B , the gas discharge port  1211  of the first TADC  1210  can be connected via flow path  1212  to intercooler  1213 , and via flow path  1214  to the gas intake port  1215  of the second TADC  1216 . The intercooler can reside in a number of different locations other than the location shown in  FIG. 12A  and  FIG. 12B . Additional TADC(s) configured in a similar manner can be added to both configurations. Both orientations can also encompass alternate setups, such as having each compression housing on opposite ends. Finally, while not shown, multiple TADC units of any variation can feed into a single TADC. 
         [0098]    As noted, the thermoacoustic prime mover in a TADC involves a hot and cold source. Heat can be delivered by any medium, such as copper wiring, preheated gas/fluid, which utilizes piping and possibly a pump, or some other combination/new variation thereof. Furthermore, a heat recovery unit (HRU)/exchanger or similar device can be used in conjunction with a hot source to facilitate the heating of gas/fluid for the thermoacoustic prime mover. As for cooling, a cool gas/fluid may be used. Furthermore; the gas/fluid may be circulated via a cooling system, which may include, but is not limited to, exchangers, fans, and pumps. 
         [0099]    With slight modifications, most of the previously discussed single acting embodiments can be converted to double acting (and vice versa), non-lubricated can be converted to lubricated (and vice versa), and any type of thermoacoustic engine/housing can be used with any type of compression housing. 
         [0100]    As noted earlier, a TADC of any variation can be used in conjunction with a gas turbine, which could power an on or offshore centrifugal compressor, an electrical generation set, or pump. The compressed air from a TADC may also be injected into an expander, which is attached to the external shaft of a gas turbine or a separate generation set providing onsite electricity. Additional TADC gas turbine applications include ships and tanks. 
         [0101]    A gas/diesel engine (stationary or moving) is another type of engine that can utilize any variation of a TADC to convert waste heat (exhaust) to usable energy. For example, the compressed air could be injected into the engine&#39;s intake tract or used with multistage compression. Alternatively, the compressed air could be applied to an expander generation set, which could provide electricity to various electrical applications. One differentiating factor between a gas turbine and a gas/diesel engine is that a gas/diesel engine relies on engine coolant, which is considerably cooler than exhaust gas, to disperse heat. While the use of engine coolant reduces the amount of heat that can be harnessed via exhaust, the engine coolant could be used as a heat sink for the thermoacoustic engine (i.e., coolant could be pumped through the cold exchanger). 
         [0102]    A TADC system of any variation also holds potential in the manufacturing environment. For example, in the coke/iron/steel industry a TADC could provide onsite compression or electricity (with expander generation set) by harnessing waste heat emitted from a coke oven, quenching tower, furnace/kiln, sintering plant, ultra high power electric arc furnace, or casting facility. Additional TADC compression/electrical applications in the metal industry include refining furnaces (includes ultra high power electric) in nickel, aluminum, zinc, and copper plants. Finally, a TADC can be used with a glass plant (furnace), cement plant (kiln), coal power plant, ammonia plant, carbon black plant, incinerator, catalytic cracker, drying and baking oven, and heat treating furnace. It is also important to note that all of these plants/systems emit flue gas. Generally, before this gas can be released into the atmosphere, the gas must be scrubbed of pollutants. However, the temperature of the gas is often too hot for the filters to operate; hence, water is used to cool the flue gas. A TADC system could be used in lieu of water, thus not only reducing the water consumption, but also improving the energy efficiency of the plant. 
         [0103]    A TADC system of any variation also has potential in the alternative energy segment. For example, a TADC system could provide low cost compression or electricity (with an expander/generation set) to remote locations with access to geothermal energy (e.g., abandoned oil wells), thereby preventing costly construction of power lines and reducing wasted energy lost through transmission. Another example would be use of a TADC with solar concentrators, which could heat tubing containing a gas/fluid (e.g., thermal oil). As with geothermal applications, the heated gas/fluid could power the TADC. Finally, many types of fuel cells exhaust high grade heat, which could also be used with a TADC to generate additional compression or electricity (with expander/generation set). 
         [0104]    All of the devices and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the devices and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the devices and/or methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain agents which are both chemically and physically related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.