Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
  • F02G1/00—Hot gas positive-displacement engine plants
  • F02G1/04—Hot gas positive-displacement engine plants of closed-cycle type
  • F02G1/043—Hot gas positive-displacement engine plants of closed-cycle type the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines
  • F02G1/053—Component parts or details
  • F02G1/057—Regenerators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
  • F02G2243/00—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes
  • F02G2243/02—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having pistons and displacers in the same cylinder
  • F02G2243/04—Crank-connecting-rod drives
  • F02G2243/06—Regenerative displacers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
  • F02G2270/00—Constructional features
  • F02G2270/30—Displacer assemblies
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
  • F02G2270/00—Constructional features
  • F02G2270/40—Piston assemblies

Definitions

• the present invention relates generally to thermodynamic machines with a Stirling cycle. More particu ⁇ larly, the present invention relates to a machine in which energy losses are limited.
• Stirling machines are used for the production of industrial refrigeration and in some military or space applications. These machines have the advantage of being used as an engine or to produce heat or cold, without using refrigerants that are generally pollutants. Another advantage of a Stirling machine is that its hot source is external and therefore this source can be obtained using any known fuel or even solar radiation.
• a gas for example air, nitrogen, hydrogen or helium
• a cycle comprising four phases: isochoric heating, isothermal expansion, cooling isochore and isothermal compression.
• FIG. 1 is a generic diagram of a Stirling machine.
• a first chamber 3 is connected to a second chamber 5 via a first heat exchanger 7, a regenerator 9 and a second heat exchanger 11.
• the assembly comprising the chambers, exchangers and the regenerator may have a cylindrical shape.
• the first and second heat exchangers 7 and 11 are, respectively, in contact with a hot source at a hot temperature Tc and with a cold source at a cold temperature Tp.
• the cold source can be a source close to the ambient temperature and the hot source a much hotter heat insulated source.
• the heat exchangers are connected to the hot and cold sources by means of heat transfer fluids flowing in pipes and driven for example by means of pumps (see below).
• the chambers 3 and 5 are closed, respectively, by movable pistons 13 and 15 which delimit the variable volumes of the chambers 3 and 5.
• the various elements of the Stirling machine shown in FIG. 1 can be movable relative to each other. to others in different ways: for example, the two pistons 13 and 15 may be movable and the regenerator 9 and the exchangers 7 and 11 to be fixed, in the case of a so-called alpha configuration.
• One of the pistons 13 or 15 can also be fixed if the central portion (regenerator) of the machine is movable.
• the assembly consisting of the regenerator 9 and the exchangers 7 and 11 is fixed and that the variable volumes of the chambers 3 and 5 are defined by a single volume separated into two parts by a movable wall called displacer.
• This configuration is usually called a beta configuration.
• Figures 2A to 2D illustrate steps of a Stirling engine cycle.
• a volume of gas is stored in the first chamber 3, the second chamber 5 having a zero or low volume.
• the gas in the first chamber 3 is heated by the hot source and its pressure increases. This causes the piston 13 to move to arrive at a state B (FIG. 2B) in which the volume occupied by the gas in the chamber 3 is greater than the volume of this same chamber in the state A.
• step A to B we recover mechanical work.
• Isochoric cooling then makes it possible to go from state B to state C in which the gas in hot chamber 3 is transferred to cold chamber 5. During this transfer, the gas stored in chamber 3 passes through regenerator 9 and reaches room 5 while cooling. The heat contained in the hot gas is "recovered” in the regenerator and the gas cools.
• An isothermal compression makes it possible to go from the state C to a state D in which the volume occupied by the gas in the chamber 5 is smaller than the volume of this same chamber in the state C.
• This compression is achieved by actuating the piston 15 in order to reduce the volume of the chamber 5.
• This step consumes mechanical energy, but less than the energy supplied during the relaxation between the states A and B.
• an isochoric transfer makes it possible to go from the state D to the initial state A in which the gas is stored in the hot chamber 3.
• the gas passes from the cold chamber 5 to the hot chamber 3 through the 9.
• the heat recovered during the isochoric cooling (step B to C) is returned to the gas during its second passage through the regenerator (step D to A).
• the gas heats up before coming into contact with the exchanger 7.
• the regenerator In motor cycle, the mechanical work recovered during the relaxation between stages A and B is used partly for isothermal compression.
• the regenerator allows the heat recovered during the transition from state B to state C is distributed to the gas during the transition from state D to state A and avoids the losses due to the entry of hot gas into the cold chamber and vice versa ( he avoids irreversibility).
• the regenerator operates as follows: when a hot gas passes through a cold regenerator, it cools by heating the regenerator and, conversely, a cold gas passing through the hot regenerator heats up by cooling the regenerator.
• it is important for the regenerator to be made of materials that conduct little heat in the direction of the gas flow, for example thermally insulating materials, in order to prevent the direct transmission of heat between parts at different temperatures. .
• machines are considered that are reversible, that is to say that can be used in motor cycle or heat pump cycle. It should be noted that this definition of reversibility differs from the current definition in which a reversible machine is a machine whose cold and hot sources can be reversed.
• An object of an embodiment of the present invention is to provide a Stirling cycle thermodynamic machine in which the different energy losses are reduced.
• Another object of an embodiment of the present invention is to provide a Stirling cycle thermodynamic machine consisting of two elementary machines operating in phase opposition.
• an embodiment of the present invention provides a thermodynamic machine consisting of at least one set of two Stirling cycle elementary machines formed symmetrically in one or more cylindrical bodies of the same axis, each elementary machine comprising first and second chambers compression / expansion device, a regenerator separating the first and second chambers and first and second outer walls for closing the volume, respectively, of the first and second chambers, the regenerator, the first and second outer walls of an elementary machine being connected rigidly to the same elements of the other elementary machines.
• each first outer wall is movable in the body
• each second outer wall is fixed relative to the body
• each regenerator is movable in the body
• two regenerators of two elementary machines formed in the same body are connected to each other via an axis located at the center of the body and the first external walls are rigidly connected to each other by means of intermediate of one or more bars extending out of the body.
• the first and second compression / expansion chambers are divided by first and second axially extending partitions, respectively, from the associated outer wall and from the regenerator, the first and second second partitions interlocking with each other during relative movements between said first and second partitions.
• the assembly formed of an outer wall and associated partitions is formed by winding a wide band and at least a narrower band whose width corresponds to the width of the walls external, the narrower band being perforated over its entire width except in contact with the chamber, the wide band being perforated on its portion located at the width of the width of the width of the gap.
• the machine further comprises parts associated with the first and second walls, outside compression chambers ⁇ compression / relaxation, in which are defined channels for bringing a heat transfer fluid in the holes formed in the winding.
• each regenerator is delimited by two non-watertight internal walls from which partitions extend axially in the regenerator chamber, each internal wall and its associated partitions being formed by winding a wide band and at least one narrower strip whose width corresponds to the width of the walls of the regenerator, the narrower band comprising, in its width, a first corrugated zone whose corrugations are oblique with respect to the length of the strip a second planar zone and a third corrugated zone whose corrugations are oblique with respect to the length of the strip, in a direction opposite to the corrugations of the first zone, the broadband comprising, opposite the first and third zones of the strip; narrower in the ⁇ rolling, wavy areas whose undulations are oblique to the length of the strip lar ge, in a direction opposite to the undulations of the narrower band.
• each elementary machine further comprises a movable cylindrical part with the regenerator formed around the regenerator in the body.
• the body comprises extensions delimiting first rear chambers of each elementary machine, opposite the second compression / expansion chambers with respect to the first external walls, the rear chambers of each elementary machine. being in direct communication through a pipeline.
• a first heat transfer fluid arrives and starts from each first rear chamber via pipes in which non-return valves are formed in the direction of circulation of the first heat transfer fluid, the movement of first external walls relative to the pipes for pumping the coolant in the pipes.
• the body comprises an extension delimiting a second rear chamber, opposite the second chambers relative to the second outer walls.
• a second heat transfer fluid arrives and leaves the second rear chamber through pipes in which are formed non-return valves in the direction of flow of the second heat transfer fluid.
• the machine comprises a combustion chamber in the second rear chamber, in contact with the second outer walls.
• the first outer walls are rigidly connected to the foot of a first connecting rod whose head is associated with a first crankshaft and the regenerators are rigidly connected to the foot of a second connecting rod. whose head is associated with a second crankshaft, the first and second crankshafts being formed around a same axis.
• Figure 1 previously described, is a generic diagram of a Stirling machine
• FIGS. 2A to 2D previously described, illustrate steps of a Stirling cycle
• Figure 3 is a simplified sectional view of an exemplary structure of a Stirling cycle machine
• FIG. 4 illustrates an exemplary structure of two half-exchangers of the machine of FIG. 3;
• Fig. 5 is a schematic diagram of an elementary machine according to an embodiment of the present invention.
• Figure 6 is a simplified sectional view illustrating a machine consisting of two elementary thermodynamic machines according to an embodiment of the present invention
• Figs. 7A-7F show stages of a cycle involving the machine of Fig. 6;
• FIG. 8 illustrates an example of two half-exchangers according to an embodiment of the present invention
• Figs. 9A, 9B and 9C further illustrate elements of Fig. 8;
• FIGS 10 and 11 are two more detailed sectional views of the machine of Figure 6;
• Figure 12 illustrates a thermodynamic machine comprising four Stirling cycle elementary machines according to an embodiment of the present invention.
• a second source of losses is typically due to temperature differences that occur within each exchanger, due to the heat resistance of the materials constituting these exchangers.
• each compression / expansion chamber is delimited by a first outer wall and a second wall connected to the regenerator, the heat exchange with a hot or cold source being made at the outer wall.
• wall or “inner wall” a room defining a compression chamber / expansion side of the regenerator, although this room is not sealed and is intended to let the gas in a axial direction.
• exchanger a compression chamber / trigger for receiving energy from a hot spring or a cold source.
• the first and second walls, and their associated partitions will be called later "half-exchanger”.
• the formation of axial partitions in the compression / expansion chambers allows that the temperature of the gas does not move away from that of the exchanger during compression / expansion and, on the other hand, the movement back and forth walls allows heat transport to the heart of the exchange structure and avoids temperature variations in the exchangers, even in the case where the partitions are a low-conductive material, as some steels.
• Figure 3 is a detailed sectional view of the body of such a Stirling cycle machine.
• the machine is formed for example in a hermetic cylinder 21 and comprises a first chamber 23 and a second chamber 25 separated by a regenerator 27.
• An exchanger consisting of two half-exchangers is formed in each of the chambers 23 and 25.
• the inner walls 41 and 43 define the location of the regenerator and let the gas circulate.
• the regenerator 27 comprises axial partitions 45, 47 which extend, respectively, from the walls 41 and 43.
• the partitions 45 and 47 are interleaved, for example in a shape identical to that of the partitions 29. and 37 or 31 and 39, and are preferably of a poor thermal conductor material but having good heat exchange properties with the gas, i.e. sufficient thermal effusivity.
• partitions 45 and 47 may be made of polycarbonate. Guides parallel to the gas flow can be added to the regenerator to ensure that the gas passing through it runs the same path in both directions of travel. It will be noted that the structure of the regenerator described here is only an example and that any type of known regenerator can be used in the machine of FIG.
• the machine is formed around a central shaft 49.
• the shaft 49 contains elements that allow the positioning of the different elements of the thermodynamic machine relative to each other.
• the partitions 29, 37, 31 and 39, or even the partitions 45 and 47, may be formed by a spiral-shaped winding of one or more sheets around the shaft 49. thermal insulation, mechanical holding and / or displacement of the various walls 33, 35, 41 and 43 in the cylinder 21 are shown in Figure 3 by hatched portions.
• FIG. 4 is a perspective view illustrating a possible solution for forming partitions dividing the chamber 23 of the machine of FIG. 3. It will be noted that, in this figure and those which follow, the number of turns and the spacing between the different turns are not drawn to scale.
• the chamber 23 is delimited by a first impervious outer wall 33, formed around the axis 49, from which partitions 29 extend.
• the wall 33 is designed to be brought into contact with a hot or cold heat transfer fluid, usually a liquid or a gas.
• the partitions 29 and the wall 33 are formed by winding, around the axis 49, strips of conductive materials.
• a broad band forming the partitions 29 and a thicker band, or several thin strips, forming the wall 33 and sealing this wall are wound around the axis 49.
• a weld can be made at the wall 33 to improve the seal.
• the compression / expansion chamber 23 On the other side of the compression / expansion chamber 23 is formed a structure similar to the structure 29/33, comprising an internal separation wall of the regenerator (not shown) from which the partitions 37 extend.
• the partitions 37 are also formed of a plate wound around the axis 49, the separator wall of the regenerator associated with the partitions 37 allowing the gas to circulate.
• the partitions 29 and 37 have, in sectional view in a plane perpendicular to the length of the chamber, spiral shapes.
• a first spiral forms the partitions 29 and a second spiral forms the partitions 37, the partitions 29 and 37 being provided to interlock with each other during the decrease of the volume of the chamber 23.
• the distance between partitions extending from the same wall is such that the ratio between this distance squared and time cycle of the thermodynamic machine is less than the average thermal diffusivity of the gas contained in the chamber. This allows the heat of the walls to have time to diffuse throughout the gas volume during a compression / expansion cycle, without requiring turbulence (laminar flow).
• the energy required for compression is proportional to the absolute temperature during compression.
• the energy recovered during the relaxation is also proportional to the absolute temperature during the relaxation. The difference between the two temperatures defines the energy balance. If the transmission of energy is made conventionally by a set of mechanical elements (rods, bearings, gears ...), these elements will take a percentage of mechanical losses on the energy they transmit , proportional to a absolute temperature.
• thermodynamic machine comprising several elementary Stirling cycle machines coupled in a particular way.
• Fig. 5 is a schematic diagram of an elementary Stirling cycle machine and its drive system according to an embodiment of the present invention. It will be noted that in FIG. 5 and in the figures which follow, moving parts together are hatched in the same way.
• the basic machine comprises a first half-exchanger consisting of an outer wall 51 from which axial partitions 53 extend in a first compression / expansion chamber 55.
• the wall 51 is movable in a body 57 delimiting the contour (for example cylindrical) of the machine.
• a regenerator 59 is formed in the body 57 and is movable in the length thereof (axially).
• the regenerator 59 extend into the chamber 55, axial partitions 61 intended to interlock with the partitions 53.
• On the other side of the regenerator, in the body 57 is formed a second compression / expansion chamber 63.
• the regenerator 59 extends in the chamber 63 of the axial partitions 65.
• a second half-exchanger consisting of an outer wall 67 from which the axial partitions 69 extend in the chamber 63, is fixed relative to the The partitions 69 are intended to fit into the chamber 63 with the partitions 65. It will be noted that the partitions 53, 61, 65 and 69 may be formed in the manner described with reference to FIG. 4.
• a first fluid circulation circuit 73 (hot or cold source) is formed to cool or to heat the wall 51, and therefore the partitions 53.
• a second fluid circulation circuit 75 (cold or hot source) is formed to cool or to heat the wall 67, and therefore the partitions 69.
• the circuits 73 and 75 are designed to bring the cold or hot fluid to the maximum. near rooms 55 and 63 (see below).
• One end of the axis 71 is connected to the base of a connecting rod 77 whose head is connected to a crankshaft 79.
• the movable wall 51 is connected to the base of a connecting rod 81 whose head is connected to a crankshaft 83, whose the axis is the same as that of the crankshaft 79.
• the heads of the rods 77 and 81 are coupled to the crankshafts 81 and 83 out of phase.
• the crankshafts 79 and 83 are associated with an engine M or alternator
• FIG. 5 The operation of the machine of FIG. 5 is slightly different from the operation of the machine of the Figure 1 since, in this case, the regenerator is movable in the machine ("regenerator-displacer").
• the mechanical system (connecting rods and crankshafts) shown in FIG. 5 is not limiting and that any mechanical system allowing the transformation of a translational movement into a rotational movement can be used, as long as the movements of the axis 71 and the wall 67 are out of phase with each other.
• an embodiment provides for mechanically coupling, and by rigid connection, elements of two or more elementary machines such as that of Figure 5.
• FIG. 6 is a simplified partial sectional view illustrating an embodiment of a thermodynamic machine consisting of two elementary machines associated with a single drive system. It will be noted that the circulation of heat transfer fluids, represented in FIG. 5 but not described in detail, is not shown in FIG. 6. This circulation will be described in detail in relation to FIGS. 10 and 11.
• FIG. 6 considers a device comprising two elementary machines M1 and M2 such as that illustrated in FIG. 5.
• references identical to those of FIG. 5 are used to describe the machines M1 and M2, each reference applied to FIG. the machine Ml having an extension "-1" and each reference applied to the machine M2 having an extension "-2".
• links with a motor or alternator such as links 77-79-81-83 of Figure 5 are not shown in this figure for the sake of simplicity.
• the elementary machines M1 and M2 are symmetrical with respect to each other and their contour is defined by a cylindrical body 57.
• Each elementary machine comprises a mobile regenerator 59-1, 59-2, not shown in detail, from and from which are formed two chambers of compression / expansion 63-1 and 55-1, 63-2 and 55-2.
• Axial partitions 61-1 and 65-1 extend respectively from regenerator 59-1 into chambers 63-1 and 55-1.
• Axial partitions 61-2, 65-2 extend, respectively, from the regenerator 59-2, into the chambers 63-2 and 55-2.
• the chamber 63-1, respectively 55-1, is delimited, opposite the regenerator 59-1, by an outer wall 51-1, respectively 67-1, from which extend axial partitions 53-1. respectively 69-1.
• the chamber 63-2, respectively 55-2, is delimited, opposite the regenerator 59-2, by an outer wall 51-2, respectively 67-2, from which extend axial partitions 53-2. respectively 69-2.
• the walls 67-1 and 67-2 are formed face to face in the body 57.
• the elements of the machines M1 and M2 are formed around a single central axis 71, the regenerators 59-1 and 59-2 being integral with this axis.
• the body 57 closes the chambers 63-1, 55-1, 63-2 and 55-2 and extends, on either side of each of the elementary machines, into portions 87-1, 87-2 defining cavities rear 89-1, 89-2, opposite the chamber 63-1, 63-2 relative to the walls 51-1, 51-2. At least two openings 91-1, 91-2 are formed in the extension 87-1, 87-2 to allow the passage of a coolant in the cavities 89-1, 89-2 to the outer walls 51-1. , 51-2.
• the body 57 also includes an extension 93 between the two elementary machines, between the walls 67-1 and 67-2, to form a chamber 94. At least two openings 95 are formed in the extension 93 to allow the passage of a heat transfer fluid to the walls 67-1 and 67-2.
• One or more rigid connections 97 are formed, in the chamber 94, to connect the walls 67-1 and 67-2 to one another, these walls being furthermore integral with the body 57. It will be noted that the rigid links 97 may not be provided. , maintaining the position of the walls 67-1 and 67-2 then being provided by the body 57.
• a rigid connection is also formed between the walls 51-2 and 51-1, from outside the body. The rigid connection is formed by a piece 99 secured to the walls 51-1 and 51-2 which passes through the extensions 87-1 and 87-2 of the body 57 and extends outside the body 57. Thus, the walls 51- 1 and 51-2 are in direct mechanical connection.
• the link formed between the walls 51-1 and 51-2 can be consolidated with a second rigid piece 101 formed symmetrically with respect to the rigid piece 99 outside the body 57.
• regenerators may, in addition to or in place of the axis 71, be connected to each other via external rigid bars similar to the bars 99 and 101.
• the shaft 71 and the walls 51-1 and 51-2 are connected to a device for transforming linear mechanical movement into a rotary movement, for example a system of connecting rods. whose rotation of the head is out of phase.
• FIGS. 7A to 7F schematically illustrate the operation of the machine of FIG. 6 in an engine cycle in the case where the openings 95 allow the passage of a heat-transfer fluid and where the openings 91-1 and 91-2 pass through a cold heat transfer fluid.
• the movements of the moving elements of the two machines are sinusoidal and that we thus move slightly away from the ideal cycle.
• the cycles followed remain cycles whose maximum theoretical yield is that of Carnot.
• the machine M 1 is at the end of the isothermal compression phase while the machine M2 is at the end of the isothermal expansion stage, which brings the regenerator 59-2 (R2) and the wall 67. 2 (H2) to be farthest from each other (the volume of hot gas in the machine M2 is the highest) and the regenerator 59-1 (RI) and the wall 67-1 (Hl) to be the closest to each other (the volume of hot gas in the machine Ml is the lowest).
• the elementary machine M1 is in the isochoric heating phase.
• the gas flows in the regenerator (RI) of the cold chamber 63-1 to the hot chamber 55-1 and the isothermal expansion on the side of the hot source begins.
• the elementary machine M2 is in the isochoric cooling phase.
• the gas leaves the chamber 55-2 associated with the hot source to the chamber 63-2 associated with the cold source.
• the machine Ml is at the beginning of the isothermal expansion phase phase while the machine M2 is at the beginning of the isothermal compression phase, which brings the volume of cold gas into the machine Ml to be the weakest (regenerator 59-1, RI, the closest to partition 55-1, Cl) and the volume of cold gas in M2 to be the highest (regenerator 59-2, R2, the farthest from the wall 51-2, C2).
• the machine M 1 is at the end of the isothermal expansion stage while the machine M2 is at the end of the isothermal compression phase, which brings the volume of hot gas into the machine M 1 to be the most high (IR furthest from H1) and the volume of hot gas in the machine M2 to be the lowest (R2 closest to H2).
• the machine Ml is in the isochoric cooling phase, and the machine M2 in the isochoric heating phase.
• the machine M 1 is at the beginning of the isothermal compression phase whereas the machine M 2 is at the beginning of the isothermal expansion phase (R 1 and C 2 the farthest, R2 and C2 nearest).
• both Ml and M2 machines have mal- func ⁇ sinusoidal like, out of phase.
• the energy of the trigger recovered by the relative movement of the regenerator 59 and the wall 67 is transmitted directly to the second machine to perform the isothermal compression phase in this second machine.
• the presence of a rigid mechanical connection between the two regenerators and between the walls 51-1 and 51-2 makes it possible to avoid mechanical losses: in fact, since this connection is rigid, there is no friction or heating at all. within this connection.
• the energy transmitted by the system in rigid connection corresponds to the difference between the energy required for compression and the energy supplied by relaxation.
• a percentage of losses, corresponding to the mechanical efficiency, is taken from an energy proportional to the difference between the absolute temperatures of the hot and cold sources, contrary to the conventional solution where this percentage is taken from each energy source, therefore proportional to each absolute temperature.
• the double architecture thus allows a simultaneity between compression and relaxation for a direct use of the energy without storage thereof. This greatly reduces the mechanical losses in the system compared to conventional structures where two or more machines operate in phase opposition and are connected by different rods to the same crankshaft and the same motor axis. In this case, the mechanical energy passes through the connecting rods and some of this energy is lost.
• the dual architecture allows the central portion to be better thermally insulated from the ambient air, as will be seen in connection with FIGS. 10 and 11.
• a difference in temperature occurring between the coolant and the walls of the exchangers also causes energy losses.
• it is sought to improve the exchanges between the heat transfer fluids and the walls, in particular by using materials having a sufficient thermal conductivity and a suitably chosen thickness.
• a temperature difference between the internal exchange walls of the regenerator and the gas can also occur. This gap is all the stronger as the heat exchange between the walls and the gas is bad.
• a temperature difference, and therefore losses, also appears, during a cycle, on the surface of the regenerator internal exchange walls: the wall is slightly cooled by the gas during a passage, and then reheated. This effect is all the more important as the thermal inertia of the regenerator is low.
• the temperature difference can be increased if the cycle is fast and a "skin effect" appears on the surface of the exchange walls, the heat does not have time to penetrate these walls and only the surface participating in the regeneration function.
• the passage of gas in the regenerator causes losses that must be minimized.
• the material that forms the regenerator itself is a little conductive and causes a direct conduction of heat from the hot part to the cold part. This loss must be minimized.
• the heat transfer fluid flow is not infinite, nor its heat capacity.
• a drop in temperature occurring between the inlet and the outlet of the heat transfer fluids causes losses in each exchanger.
• the exchangers are formed using coils made with mutually isolated turns, the circulation of the fluid being carried out radially in contact with each exchanger.
• the regenerator is also constituted by turns which are isolated from one another, each part of the gas then has a laminar movement back and forth successively in a turn of the same radius of the heat exchanger, the regenerator and the heat exchanger. cold.
• Each part of gas at a given radius of the axis then follows a Stirling cycle between two temperatures that vary depending on the radius.
• FIG. 8 illustrates an embodiment of two half-exchangers delimiting a compression / expansion chamber.
• FIGS. 9A to 9C illustrate in greater detail portions of the half-exchangers of FIG. 8.
• Figure 8 is a perspective view of a structure of a compression / expansion chamber 63. In this figure, the body of the machine has not been shown for the sake of clarity.
• the chamber 63 is delimited by a first outer wall 51 from which extend axial partitions 53 in the chamber and a second wall 59 associated with a regenerator.
• partitions 53 and 61 are facing and are intended to nest when the volume of the chamber 63 decreases.
• the outer wall 51 is intended to be brought into contact with a cold or hot source. To improve the exchanges between the wall 51, in contact with the partitions 53, and the cold or hot fluid, it is expected to form this set in a particular way, by winding together several bands.
• a first wide band 111 one end of which forms the partitions 53, is wound with one or more narrower strips 113 whose width corresponds to the width of the wall 51.
• the band or strips 113 are pierced with holes 115 along their entire width. , except on a thin width on which will be achieved the seal between the working gas (in the chamber 63) and heat transfer fluid, as shown in Figure 9A.
• the wide band 111 part of which forms the partitions 53, is also pierced with several holes, but only on its width corresponding to the width of the gaps 113.
• the winding of the strips 111 and 113 is provided so that, at the limit of the chamber 63, the holes stop to allow the sealing of the chamber 63. To improve this seal, this end in contact with the chamber 63 will be glued, brazed or welded, for example by laser, after winding to form the sealed portion of the chamber 63. Thus, the winding is porous at the source of heat-transfer fluid and sealed at the chamber 63.
• the porous portion in the strips 111 and 113 makes it possible to circulate the heat-transfer fluid as close as possible to the chamber 63 and the partitions 53.
• the holes are dimensioned and positioned so that each hole of a given band always opens at the level of at least one hole in each band it contacts.
• This staggered structure makes it possible to make holes at different distances from the edge of the strips in communication. This allows the heat transfer fluid to penetrate easily into the thickness of the porous material.
• a row of holes is positioned on the edge of the strips 111 and 113, on the side of the coolant, to allow the fluid to enter the porous structure.
• the pitch of the holes of the strips is chosen so that there is no appearance of repetitive structure in the porous part which could affect the circulation of the fluid. For example, if the total thickness of the ribbons that are wrapped with each other is e, it will be avoided that the pitch of the pattern formed by the holes is close to an integer multiple of ne. A large diameter of the holes allows a good circulation of the cooling fluid, but this diameter must be chosen to allow good conduction of heat by the material remaining around the holes.
• Figure 9A illustrates a strip 113 in which holes 115 are formed in a suitable pattern.
• the holes 115 are formed on several lines in the length of the strip, staggered.
• the holes 115 of the same line may be spaced apart by a distance of between 4.7 and 4, 9 mm, preferably 4.8 mm.
• the holes of two adjacent lines have their centers located on an axis forming an angle of about 60 ° with respect to the width of the strip.
• holes formed in two adjacent lines may be separated by a distance between 1.3 and 1.4 mm (distance between two holes at the same level in the length of the strip between 2.5 and 3 mm).
• Other dimensions are shown in Figure 9A as an example.
• the efficiency can also be improved if a temperature difference is maintained within the winding between the inlet and the outlet of the coolant.
• a radial flow of the fluid it is sought to limit the thermal conductivity in the radial direction of the entire structure.
• regenerator is made of a thermal insulating material whose thermal effusivity and thermal inertia are sufficient to prevent temperature variations during a cycle.
• the regenerator is delimited by two internal walls
• a regenerator To produce a regenerator, provision is made to form a winding of several strips, a first wide band being intended to form the partitions 61 of the exchanger and one or two second strips 117, which are narrower, ensuring the passage of the gas, the maintenance of the structure and formation of the regenerator wall.
• a third strip similar to the first, may be provided in the same winding or shifted to form the internal partitions of the regenerator (not shown). As shown in FIG. 8, 9B and 9C, the one or more thin strips 117 and a portion of the wide strips located in the winding at the thin web are deformed.
• FIG. 9B illustrates the deformation of the band forming the partitions 61, at its portion intended to be wound with the narrower strip or strips 117.
• the band 61 comprises, in the width of this portion, and throughout its length, a sequence of three zones 119, 121 and 123.
• the zone 119, the closest to the regenerator, is corrugated, the corrugations being oblique with respect to the length of the strip 61.
• the central zone 121 is flat and the zone 123, the closest to the chamber 63, is corrugated, the corrugations being oblique symmetrically with respect to the corrugations of zone 119.
• the band 117 comprises, along its width, three zones, the first being undulated, the second being plane and the third being also undulated, the corrugations of the first and third zones being oblique in different directions.
• the winding of the strips 61 and 117 is provided so that overlapping corrugations are oblique in different directions. This provides a constant distance between the partitions 61 in the chamber 63, and allows the flow of gas in the regenerator.
• the different corrugated areas can be formed by stamping.
• FIG. 9C illustrates an example of possible dimensions for the corrugations of the corrugated portions of the band 117 (identical, symmetrically, to the corrugations of the band 61).
• the first and third corrugated zones may be formed over a width of the order of 3.5 mm and the second planar zone may extend over a width of the order of 3 mm.
• the corrugations of the first and third zones may have a displacement in the thickness of 0.276 mm and be oriented with respect to the length of the strip of 30 ° (symmetrically for the first and third portions).
• the partitions internal to the regenerator extend into it while being nested, the nesting being made possible by the presence of the ripples on the end of the internal partitions at their level on the walls.
• the gas circulates in the almost planar spaces formed by successive layers of spirals.
• the geometry leads to a circulation of gas (between two planes or quasi-planes) in the regenerator which allows to maximize the ratio number of Nusselt on coefficient of friction in laminar regime (inevitable regime considering the dimensions and speeds of gas). This maximizes heat exchange in the regenerator while minimizing losses by viscous friction.
• the material forming the elements of the regenerator is a poor thermal conductor to avoid direct thermal conduction between hot and cold source, the heat capacity of the assembly being sufficient to prevent the temperatures inside the regenerator from changing too much during the heating. cycle.
• the thermal diffusivity of the material is sufficient to allow the entire mass of the material to be mobilized to participate in the heat exchange during a cycle and to avoid a "skin effect" in the material which would involve variations temperature of the walls during a cycle.
• one or both ends of the wide band 61 may be cut at an oblique angle to prevent deformation of the winding, for example at 45 ° by ratio to the length of the band. It's the same for band 111.
• FIGS 10 and 11 are two sectional views in more detail of a machine consisting of two elemen tary ⁇ machine according to an embodiment of the present invention, and elements for limiting the losses in these machines. It will be noted that in these figures the structure of the regenerators has not been shown in detail and that the partitions formed in the compression / expansion chambers are shown for illustration and not to scale.
• thermodynamic machine of Figures 10 and 11 comprises two elementary machines M1 and M2.
• each elementary machine Ml and M2 comprises a first and a second chamber 55, 63, separated on one side by a regenerator 59 fixed on an axis 71 and on the other side by an outer wall 51, 67.
• the axis 71 extends along the entire machine (see Figure 11). Nested axial partitions extend into each of the chambers.
• a chamber 89 is formed, opposite the chamber 63 relative to the wall 51 by an extension 87 of the body 57 of the machine.
• the chamber 89 is intended to receive a first heat transfer fluid.
• the body 57 is also closed between the two elementary machines to form a chamber 94 located between the walls 67-1 and 67-2 and intended to receive a second heat transfer fluid.
• the first heat transfer fluid is the cold fluid and that the second heat transfer fluid is the hot fluid (hot with respect to the cold fluid).
• the opposite is also possible.
• the 133-1 and 133-2 parts are elec trically insulating ⁇ to prevent corrosion due to contact of the coolant with two metals very different in nature in contact electric between them.
• Parts 133-1 and 133-2 make it possible to organize the circulation of the fluid coolant in the porous portion of the outer walls 51-1 and 51-2 (see Figure 8).
• Each part 133-1, 133-2 is provided with channels 135-1, 135-2 which allow a flow of fluid along the wall 51-1, 51-2.
• channels 135-1, 135-2 allow a flow of fluid along the wall 51-1, 51-2.
• the parts 133-1, 133-2 allow the heat transfer fluid is brought into contact with the entire surface of the wall 51-1, respectively 51-2, according to a radial flow in the porous portion.
• the coolant coming from a cold source arrives and leaves the channels 135-1 and 135-2 via fluid circulation pipes 137-1, 137-2, integral with the 133-1, 133-2, which grout ⁇ in the fluid inlet and outlet pipe 91-1, 91-2 during the movement of the walls 51-1, 51-2.
• Pistons 139-1, 139-2, integral parts 133-1, 133-2 are connected to the outer rigid bars 99 and 101 to maintain the walls 51-1 and 51-2 in motion and are traversed by the pipes 137-1 and 137-2.
• the cold fluid inlet for the two elementary machines may be formed of a single fluid inlet separating between the two machines to reach the fluid inlets 91-1 and 91-2 (see FIG. 11).
• parts 141-1, 141-2 similar to the pieces 133-1, 133-2, fixed relative to the body 57, are formed along the walls 67-1 and 67-2, these parts comprising channels similar to the channels 135 for the supply and the outlet of the hot fluid.
• Pipes 143-1 and 143-2 are formed in the chamber 94 to bring the hot fluid into the channels through the body.
• Rings 145 are provided around the axis 71, at the parts 133 and 141 and the walls 51 and 67 to ensure sealing at the axis 71.
• the rings 145 may be in an electrical insulating material to avoid electrical contact between the exchanger and the rest of the structure, and for example to allow, by electrical contact measurement, the detection of an accidental contact between nested half-exchangers.
• the body fulfills several functions: thermally isolating the hot and cold sources between them, thermally isolating a source with respect to the ambient air, ensuring the mechanical resistance to the pressure of the working gas by accepting a tangential stress, ensuring the mechanical strength to the pressure of the working gas by accepting an axial stress and sealing the working gas, especially in the case where the working gas is hydrogen or helium.
• a first portion of the body, not shown in the figures, in contact with the working gas can be formed of a thin layer, optionally thermally conduc ⁇ trice having a low permeability and good resistance to gas, e.g. aluminum or preferably stainless steel in the case of using hydrogen as a working gas. Its fineness prevents direct thermal conduction between the sources (typically of the order of a millimeter or less).
• a layer 147 of a poor thermal conductor material whose mechanical strength is not sufficient to hold alone the internal pressure of the working gas for example a plastic such as a polyacetal, a polyamide, a polyimide, a poly-x-sulfone or mixtures with base of resins and mineral fibers.
• a plastic such as a polyacetal, a polyamide, a polyimide, a poly-x-sulfone or mixtures with base of resins and mineral fibers.
• the layer 147 Around the layer 147 are formed metal circles 149 ensuring the mechanical strength and possibly being thermal conductors. To ensure this mechanical strength, they are preferably spaced apart from each other by a small space in front of the thickness of the layer 147. The multitude of spaces between the successive circles (not shown) makes it possible to avoid direct thermal conduction between the sources.
• thermal insulation layer 151 Surrounding the circles 149 is formed a thermal insulation layer 151. In contrast to the other layers, the latter must limit the heat transport between the inside and the outside of the body, perpendicular to the structure, the other layers limiting the transport of heat. heat in the length of the structure. As seen in Figure 11, the thermal insulation 151 extends along the inlet and the outlet of hot heat transfer fluid.
• the layer 151 may be made of a mineral wool.
• Tie rods 153 held in position by washers and nuts at the ends of the body, present all around the body (only one is shown), may be provided to allow the holding of the assembly in the length of the machine (unlike the straps 149 which allow the mechanical resistance to the pressure in the direction tangential to the machine). 6. Losses due to travel
• the insulating piece 155 is movable with the regenerator 59 and is provided with an infrared reflective coating.
• the piece 155 is in contact with the body over part of its length to ensure the relative sealing between the compression / expansion chambers and to limit the direct heat transfer between these chambers.
• a space, provided on the rest of its length, between the part 155 and the body makes it possible to limit the losses due to the displacement.
• the part 155 can be made in the form of two vacuum-insulated nested cylinders to reduce its thermal conductivity in the direction of the thickness.
• the rear volume losses are related to the compression and expansion of the gas volume located at the rear of the pistons in the rear chambers 89-1 and 89-2. This compression is not perfectly adiabatic, it causes losses. If the rear of the pistons is open, these losses correspond to the losses associated with the emission of sound waves (generally infrasonic for this type of machine).
• check valves 159 in the fluid flow direction, on both sides of the machine.
• it is intended to fix, in the body of the machine, in the chamber 94, fixed tubes 161 in contact with the channels closest to the axis 71 in the rooms 141-1 and 141-2.
• the circulation in the fixed walls 67 can advantageously be achieved by an integrated solution of piston pumping, which pistons are in rigid mechanical connection with the movement of the regenerators 59-1 and 59-2 (or, in a case not shown, with the movement of pistons 139-1 and 139-2).
• Pistons 163 movable with the axis 71 (connected to the regenerators), penetrating into the various tubes 161, allow the pumping of the coolant during the movement of the axis 71. They are preferably distributed symmetrically about the axis, by example is provided two symmetrical pistons, to allow a balance of forces and an action without parasitic torque on the axis and its guides.
• regenerators when the regenerators are in motion, it activates the pistons 163 in the tubes 161 and allows, in each elementary machine, the pumping and expulsion of the hot heat transfer fluid in a suitable manner.
• the movement of the pistons to create volume variations in the heat transfer fluid inlet and outlet tubes 137.
• part of the tubes 137 is parallel to the movement of the moving pistons and the length of these tubes varies with the movement of the pistons.
• two tubes 137 slide one inside the other to obtain this variation in length. It will also be possible to form a bellows in these tubes to obtain an identical effect.
• the pipes 91-1 and 91-2 are fed in parallel through a common pipe.
• the pumping and the expulsion of fluid in each elementary machine is thus carried out in phase opposition, the volume variations of the heat transfer fluid circuits being compensated for exactly. This makes it possible to ensure that the pumping is performed without variation of the total volume of the heat transfer fluid circuit. Since the speed of the machine is proportional to the thermal power taken and the necessary fluid flow is also proportional to this power, a volumetric pumping ensures operation with constant temperature differences.
• the direct mechanical transmission avoids mechanical losses and all losses and additional costs associated with the installation of a fluid circulator (with power, motor ). Thus we combine low losses with simplicity (no need to regulate) and optimum operation by construction.
• Dynamic seals cause friction.
• a mini leak provided when the piston 139-1, 139-2 is in the given position makes it possible to pump the unplanned leaks in the other direction during the cycle and to limit the constraints on the dynamic seals.
• This leakage makes it possible to determine the moment of the cycle when the pressures are equal on either side of the piston, for example when the piston is in the position where the working gas has a maximum volume. The rest of the movement allows the uncontrolled leaks that would have occurred during the cycle to be pumped in the opposite direction. This reduces the stress on these seals.
• a small notch (not shown) can be formed in the body 57, in the chamber 89-1 and 89-2, at the piston 139-1, 139-2 when the chamber 89-1, 89 -2 has the lowest volume.
• the membranes or bellows may possibly be double, for example to detect a large leakage through a system for detecting the presence of gas between the two walls.
• seals 167-1, 167-2 may be formed around the pistons 139-1, 139-2 to permit dynamic sealing at the periphery thereof. Seals, not referenced in the figures, can also be provided at the level of the guide of the regenerator assembly, around the shaft 71 and at the pistons 139-1 and 139-2 moving in the pipes 91-1 and 91 -2, at the level of the integrated circulation of the coolant. Note that these joints may be replaced by bellows.
• a system for balancing the working gas pressure in each of the compression / expansion chambers comprising a valve making it possible to change the proportions of proportionality between the speed and the thermal power in order to adjust the operating conditions.
• ⁇ tion especially if one of the parameters (such as speed) is fixed (for example by another coupled machine).
• pressure sensors in the chambers will be provided to obtain the instantaneous pressure of working gas, and in a reserve formed outside the machine.
• the valve will be opened at the time of the cycle when the instantaneous pressure of the working gas is lower than the reserve and inver ⁇ ment.
• two valves and check valves may be used, the seats of the valves being closer to the inside of the machine to prevent dead volumes.
• the working fluid is hydrogen and where irreversible micro-leaks of gas appear through the walls or membranes, it can be provided to couple the pressure equalization system to a microsystem injection of gas, for example a mini-electrochemical cell, to counteract these micro-leaks. 11. Losses related to guidance
• the spiral 51-1, 51-2 in contact with the pistons, can be wound on a mandrel (not shown) serving as a guide and ensuring a relative sealing.
• the mandrel can be screwed onto the shaft 71 by an electrically insulating ring to prevent corrosion (not shown).
• the two spirals constituting the half heat exchangers on either side of the regenerator can be wound on two aligned mandrels 169-1 and 169-2 and held by a thermally insulating ring (not shown) on which the regenerator can itself even be wrapped.
• the fixed spiral constituting the fixed half-exchanger hot side
• a slippery or rolling connection can be provided on a plane between an intermediate piston and the pistons 139-1 and 139-2, the plane being perpendicular to the guiding axis, the point application of the force exerted between the piston and the intermediate piston located on the guide axis.
• This plane can also be a sphere arc centered on the mandrel 169.
• the intermediate piston can be pre-loaded with a bearing.
• a rolling connection has a very low coefficient of friction, which makes it possible to limit the losses due to these forces.
• most of the driving force of the pistons 139-1, 139-2 passes through the axis of the guides which prevents a harmful torque occurs at the guide.
• guide pieces can be added to the machine, for example at the two spirals of the hot flash chamber.
• guiding is carried out in cold part, and the guide piece around the shaft 1 can transmit the guidance to the hot part via a thermally insulating part.
• FIG. 12 illustrates a thermodynamic machine comprising two machines each consisting of two Stirling cycle elementary machines.
• a first dual machine comprises two elementary machines M1 and M2 formed similarly to the machine illustrated in Figures 10 and 11. This first machine will not be redescribed in detail.
• a second machine consisting of two elementary machines M3 and M4 (references followed by "-3" and "-4" for elements similar to the elementary machines M2 and M3) is formed in parallel with the first machine.
• the second machine is similar to the first machine except that, in the central part of the machine, rather than providing a hot fluid circulation circuit, a combustion chamber 173 is formed in the machine enclosure (at the level of the first machine). chamber 94 of the first machine).
• the central temperature of the second machine is thus higher than the central temperature of the first machine.
• elements similar to those of the first machine namely combustion / expansion chambers separated by regenerators and walls / pistons.
• On the warm side of the second machine no circulation is direct and the combustion chamber is fed with reagents which are introduced in conventional manner by pumps not shown.
• These pumps can for example be connected to the motor shaft by a conventional mechanical transmission (gear, chain, ⁇ belt ...), or be associated with an electric motor powered by electricity generated by an alternator.
• the combustion chamber 173 may be equipped with elements 175 capable of improving the heat exchange with its walls (for example exchange fins with the gases extending into the combustion chamber), and may be equipped with elements 177 may improve the mechanical strength at the pressure difference of the working gases in the two half-machines (reinforcement bars for example).
• the general principle is to ensure that the mechanical energy supplied by a machine is directly used by other machines.
• a rigid mechanical connection between the different machines makes it possible to directly transmit the mechanical energy without loss.
• the rigid bar or bars 99 and 101 are connected to similar rigid bars connected to pistons and outer walls of the second machine.
• An additional rigid bar 179 may be formed on the other side of the second machine to balance the torques applied to this machine.
• regenerators shown have longer lengths than in the first machine. Indeed, on each cycle, these regenerators must recover and return to gas energy proportional to the temperature difference between the sources. This temperature difference is assumed to be greater in this case, hence the presence of a longer regenerator.
• the regenerators of the two machines are also interconnected.
• the shafts 71 of the two machines are interconnected by a rigid bar 181 external.
• the rigid bar 181 may be double and be formed on either side of the shafts 71 and reconnect to the outside of the machine.
• the first machine can function as a heat pump, the isolated central part being equipped an integrated system of circulation of heat transfer fluid in contact with the cold source (for example sensor pipes in the soil of a geothermal installation).
• the hot central part may be a biomass combustion zone, and the heat transfer fluids circulating in the outer parts of the machines equipped with integrated circulations may be connected to a device for transporting the heat produced in a heating installation, for example radiators or a heated floor.
• a portion of the heat produced by the combustion allows the production of mechanical energy in the second machine, this mechanical energy being used to operate the first machine heat pump by a rigid mechanical link without loss.
• This absence of loss makes it possible to obtain a high coefficient of performance of the heat pump part, and thus to add a large part to the heating power obtained for the same fuel consumption.
• the setting of the transmitted powers can be done by adjusting the pressures of the working gases. You can also take a portion of the power for a cogeneration function of electricity, in addition to heat.
• the cold source could for example be a source of geothermal origin and the hot source a source connected for example to a heated floor.

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• Engineering & Computer Science (AREA)
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• General Engineering & Computer Science (AREA)
• Engine Equipment That Uses Special Cycles (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

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• 2009
  • 2009-09-21 FR FR0956472A patent/FR2950380A1/fr not_active Withdrawn
• 2010
  • 2010-09-21 US US13/496,673 patent/US20120198834A1/en not_active Abandoned
  • 2010-09-21 EP EP10770852A patent/EP2480777A1/de not_active Withdrawn
  • 2010-09-21 CN CN201080052726XA patent/CN102753806A/zh active Pending
  • 2010-09-21 WO PCT/FR2010/051973 patent/WO2011033243A1/fr active Application Filing

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