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
  • F02G1/0435—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 the engine being of the free piston type
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
  • F02G2243/00—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes
  • F02G2243/30—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders
  • F02G2243/40—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders with free 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
  • F02G2243/00—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes
  • F02G2243/30—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders
  • F02G2243/50—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders having resonance tubes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
  • F02G2243/00—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes
  • F02G2243/30—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders
  • F02G2243/50—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders having resonance tubes
  • F02G2243/52—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders having resonance tubes acoustic
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
  • F02G2243/00—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes
  • F02G2243/30—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders
  • F02G2243/50—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders having resonance tubes
  • F02G2243/54—Stirling type engines having closed regenerative thermodynamic cycles with flow controlled by volume changes having their pistons and displacers each in separate cylinders having resonance tubes thermo-acoustic
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • 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
  • F02G2270/45—Piston rods
• • 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
  • F02G2280/00—Output delivery
  • F02G2280/10—Linear generators

Definitions

• the present invention relates to a method for transmitting mechanical energy between a transfer piston of a Stirling machine and a movable member of a generator or an electric motor, the transfer piston being mounted in a cylinder, according to which a working gas is periodically displaced using said transfer piston between an expansion chamber and a compression chamber associated respectively with two working faces of said transfer piston by passing said gas through an exchanger hot, alternately cold, connected to a heat source, a regenerator and a cooling exchanger connected to a heat sink and an elastic restoring force is exerted on this transfer piston.
• the object of the present invention is to remedy at least in part the above-mentioned drawbacks.
• this invention firstly relates to a method for transmitting mechanical energy between a transfer piston of a Stirling machine and a movable member of a generator or an electric motor such as nor by claim 1.
• This invention also relates to a device for implementing this method, according to claim 10.
• Figure 1 is a diametrical sectional view of this embodiment
• Figure 2 is a view of a variant of Figure 1
• Figure 3 is an elevational view of the device according to Figures 1 or 2
• FIG. 4 is a vector diagram
• FIGS. 5 and 6 are explanatory diagrams relating to the method
• FIG. 7 is a diagram relating to the performance of the cycle in relation to the work per cycle
• Figures 8 to 10 are diagrams relating to the dimensioning and the behavior of the resonator
• Figure 11 is an elevational view, partially in section of the second embodiment
• Figures 12 and 13 partially illustrate two variants for heating a Stirling engine
• Figures 14 to 16 illustrate three variants in which Stirling engines are coupled by resonance tubes
• FIG. 17 illustrates a heating mode applicable to the variants of FIGS. 14 to 16.
• the device illustrated in FIG. 1 comprises an elongated casing 1 formed by two cylindrical compartments 2, 3, assembled on an intermediate element 4, playing the role of frame.
• the cylindrical compartment 2 comprises a cylindrical housing 5, constituting a working volume of a Stirling engine, in which a two-part transfer piston 6, 6a is mounted, free to move in the longitudinal axis of the cylindrical housing 5.
• the volume located between the part 6 of the transfer piston 6, 6a and the external end of the housing 5 is that which is in contact with a hot exchanger 7 connected to a hot source
• the cylindrical compartment 3 contains a volume in which a mobile element of an electric generator, here the inductor 11 constituted by a cylindrical element carrying permanent magnets, is integral with the periphery of an annular member 12, the internal edge of which is integral with an elastic suspension member 14, constituted by annular flat springs, the peripheral edges of which are fixed to the frame 4 and the internal edges of which are integral with a rod 17, one end of which is fixed to the part 6a of the piston transfer 6, 6a.
• the internal edge of a second elastic suspension member 15 similar to the member 14, is fixed to the other end of the rod 17, while its periphery is fixed to a support 13 integral with the frame 4.
• the armature of the generator is formed by windings 16.
• Part 6a of the transfer piston 6, 6a and the rod 17 pass through the bottom of the closed volume 10 formed in the intermediate element 4 with a clearance between 30 and 50 ⁇ m.
• Such a clearance is perfectly acceptable both from the point of view of manufacturing tolerances and of the influence of leaks from the working gas on the energy yield and on the restoring force of the compressed gas in the closed volume 10.
• This resonator has the role of replacing the second piston, which according to the process which is the subject of the invention, is no longer used to produce energy, all the energy being produced by the transfer piston 6, 6a as will be explained. below, but serves to amplify the pressure wave and to ensure an appropriate phase shift between the displacement of the transfer piston 6, 6a and the pressure variations p in the working volume.
• this tubular resonator 18 advantageously ends in a Helmholtz volume 19.
• the part of this resonator which is in the Helmholtz volume ends in a flaring 18a.
• the transfer piston 6, 6a then plays the double role of transferring the working gas between the expansion chamber V E and the compression chamber V c and for producing all the motive energy transmitted to the inductor 11, for as long as certain conditions, which we will talk about now, are fulfilled. To achieve this objective, it is necessary to determine the ratio between the surface a c , delimiting the compression chamber of the transfer piston 6, 6a and that a E of this same piston, delimiting the expansion chamber.
• the variation in the quantity WG of working gas in the working volume of the Stirling engine gives rise to a variation in pressure p w , which is in phase with the variation in the quantity WG of working gas.
• the variation of the pressure p in the volume of Stirling engine work corresponds to the vector sum of the two partial pressures p x and p w .
• FIG. 5 shows the variation of the position X of the transfer piston 6, 6a and the variation of the pressure as a function of time (or of the angle ⁇ ). This representation corresponds schematically to that of FIG. 4.
• the pressure decreases, the working gas is largely in the hot or expansion chamber; when it increases, the working gas is mainly in the cold or compression chamber.
• the displacement X of the piston 6 must precede the pressure variation p.
• FIG. 6 represents the variation of the quantity WG of working gas in the Stirling working volume and the pressure p in this volume.
• the quantity WG of gas decreases, the pressure is greater than during its return where the quantity WG of gas increases. There is therefore an energy transport from the Stirling volume to the tube, which compensates for the friction losses in this tubular resonator 18.
• Figure 4 shows that p x must be opposite to X. If p x becomes zero, or oriented in the direction of X, no energy is transmitted to the tubular resonator 18 to compensate for friction losses. Therefore, the pressure wave cannot be maintained and the machine stops working.
• FIG. 7 gives an example of the efficiency of the cycle ⁇ c calculated as a function of the work provided by cycle E, with the wall temperature T H of the expansion chamber V E and the amplitude X of the transfer piston 6, 6a as setting.
• the temperature of the cold exchanger T close to the temperature T c, is approximately 50 ° C.
• the net efficiency of the generator can be obtained by multiplying the efficiency of the cycle by the efficiency of the heating means and that of the alternator.
• the Stirling engine should always operate at expansion chamber temperatures between 600 ° and 700 ° C. In this range, the temperature T H of the expansion chamber V E mainly influences the power, to a lesser extent the efficiency. But by lowering the temperature to 400-500 ° C, the efficiency and power decrease sharply, mainly because, under these conditions, the pressure variation p x induced by the movement of the piston becomes small and finally disappears completely.
• the lateral rigidity of the mechanical suspension of the transfer piston 6, 6a is ensured by flat springs 14, 15 of the type described in “Recent developments in cryocoolers” Ray Radebaugh 19 TM International Congress of Refrigeration 1995 Proceedings Volume Illb, allows it to oscillate perfectly along the longitudinal axis of the cylindrical housing 5, so that it is not necessary to use pneumatic bearings to center it.
• the transfer piston 6, 6a can be centered with great precision. Because of the suspension pneumatic of this transfer piston and consequently, of the low forces necessary for the elastic suspension elements constituted by the annular flat springs 14 and 15, the amplitude of the transfer piston 6, 6a can be increased from 25% to 50% by relation to the device described in "Free-piston Stirling design features" Neill W.
• the use of a single movable piston simplifies initial adjustment, start-up and power control significantly compared to conventional Stirling free piston systems.
• the rigidity of the suspension of the transfer piston 6, 6a and therefore the phase angle can be adjusted by adjusting the pressure of the working gas in the working volume of the Stirling engine.
• the natural frequency of the tubular resonator 18 can be adjusted by varying the composition of the working gas, that is to say its molecular mass.
• the engine is then started by first bringing the working gas temperature in the expansion chamber V E to a value T H at which the working gas pressure becomes independent of the position of the piston. transfer.
• the load on the Stirling engine is thus reduced to a minimum (losses by internal friction of the engine and by periodic flow through the exchangers and the regenerator).
• the temperature T H will be adjusted to the optimum working temperature.
• Power control is very easy. We adjust the amplitude of the transfer piston 6, 6a and therefore the power of the Stirling engine, by adjusting the braking force exerted by the electric generator at a determined value. For given temperatures of the gas T H , T c in the expansion chambers, respectively of the compression chambers, the output power varies in proportion to the amplitude of the transfer piston 6, 6a.
• the heating power of the burner (not shown) intended to heat the working gas of the expansion chamber V E is continuously adjusted to maintain the desired temperature T H in this expansion chamber V E. Under normal conditions, the amplitude of the transfer piston can therefore be precisely controlled. It is therefore not necessary to provide additional dead volume to avoid shocks in the event of accidental overshoot of the transfer piston.
• the natural frequency of the tubular resonator 18 only depends on the average temperature of the working gas therein. This temperature can be precisely adjusted to the desired value by means of an additional heat exchanger 20 arranged in the Helmholtz volume 19 and by controlling the thermal energy extracted. This allows the phase angle of the resonator to be adjusted relative to the other variables of the system.
• the extraction of heat from the tubular resonator 18 makes it possible to reduce the cooling of the working gas situated in the compression chamber V c , which makes it possible to simplify the cold exchanger of the Stirling engine. Its dead volume and / or its losses by pneumatic friction can be reduced, providing an additional advantage to the device which is the subject of the present invention.
• the pressure of the working gas in the Stirling volume varies cyclically as a function of the oscillation of the pressure wave in the tubular resonator 18.
• the energy dissipation is then exclusively due to the friction losses of the fluid and remains moderate, at least for the pressure variations considered in this application.
• the parameters of tubular resonator 18, an example of which follows, must be adjusted to those of the Stirling process to ensure that these components interact appropriately, i.e. the wave is driven by the Stirling cycle and that the resulting pressure variations maintain the periodicity of the Stirling cycle.
• the tubular resonator 18 can have a total length including the Helmholtz volume 19, of approximately 1.6 m, and a temperature T of 40 ° C.
• the average pressure p 0 of the gas is 4 MPa and the resonant frequency of this resonator is 50 Hz.
• a working gas whose molecular mass is higher than that of helium such as a mixture of helium and argon or carbon dioxide with a molecular mass M of gas of 14 kg / kmol.
• the minimum section S m i n of the tubular resonator 18 is, in this example, 4.75 cm 2 .
• the working gas volume V s of the Stirling 2 engine is 1000 cm 3
• that of the Helmholtz volume 19 is 6000 cm 3 .
• the tubular resonator can be extended inside the Helmholtz volume 19. Since this portion of the tube is only exposed to limited pressure differences, its wall can be thin and can thus easily be put into conical shape 18a preventing the formation of pressure waves with a steep front.
• FIG. 8 An example of the distribution of the section along the tube 18 of the resonator is shown in the diagram in FIG. 8.
• the left end of the diagram corresponds to the end of the tube 18 in communication with the Stirling compartment 2, while the right end corresponds to that which communicates with the Helmholtz volume 19.
• the diagram in FIG. 9 represents nine values at regular intervals of the speed of flow of the working gas in the tube 18 compared to the speed of sound (therefore the Mach number) as a function of the position in the tube 18 during a cycle, while the diagram in Figure 10 shows the distribution of the working gas pressure compared to the average pressure during the same cycle.
• the pressure diagram clearly shows that with appropriate sizing of the tube, no shock occurs at the resonance conditions of the tube 18.
• the pressure in the Stirling 2 volume varies sinusoidally. Pressure and speed are orthogonal functions, that is to say that if the pressure takes an extreme value, the speed of the working gas is zero and vice versa.
• the range indicated takes account of the fact that, on the one hand, the coefficient of friction of the working gas in unsteady state can differ from that of an established regime, on the other hand that the roughness of the tubes is known only approximately.
• the volumes of working gas displaced are of the order of a hundred cm 3 .
• the cylindrical parts of the tube are typically only diameters from 2.5 to 4cm. It can easily be curved or rolled up so that the entire device occupies as small a volume as possible.
• the device illustrated in FIG. 3 can have a height of 90cm, a width of 60cm and a depth of 40cm.
• the variant illustrated in FIG. 2 differs from the embodiment in FIG. 1 only in that the elastic return member of the transfer piston 6, 6a is no longer formed by the closed volume 10, but directly by the cylindrical compartment 3 containing the alternator. Indeed, this compartment is also a closed volume and can therefore also serve as an elastic return member and thus replace the volume 10 of the embodiment of Figure 1. So far we have described only one form in which the mechanical energy produced is transmitted to a reciprocating member such as that of the free transfer piston 6, 6a of the Stirling engine. As a variant, it would also be possible to transform this alternating movement into a rotary movement as is well known in the case of internal combustion engines or steam engines.
• FIG. 11 Such a variant is illustrated by FIG. 11 in which we find the end of the free transfer piston 6a 'and that of the resonance tube 18' communicating with the cold room or compression volume V c .
• a rod 21 is slidably mounted in a cylindrical guide 22 by linear bearings 31.
• a connecting rod 23 is articulated by one end to the rod 21 and by its other end, to a crankshaft 24 integral with the axis of a rotary electric generator for example, mounted in an enclosure 25.
• the tubular resonator 18 may be constituted by two identical tubular elements arranged in diametrical opposition relative to said transfer piston 6, 6a so as to balance the lateral forces exerted on this transfer piston.
• the tubular resonator 18 can be connected to the expansion volume V E or hot compartment of the Stirling engine, provided that the whole of this tube is kept warm and does not constitute a heat sink.
• FIG. 12 illustrates a variant in which the Helmholtz volume 19 is placed in a heating enclosure 26, heated by gaseous, liquid or solid fuels, while the tube 18 is surrounded by thermal insulation 27. It is thus possible to increase the temperature of the working gas contained in the tubular resonator 18 above the temperature T H of this gas in the expansion volume V E. The tubular resonator 18, 19 can then partially or entirely replace the hot exchanger 7 of the Stirling engine.
• the exchange surface can be increased using fins 30 inside and / or outside of the Helmholtz volume 19. Since the diameter of the tube 18 is already of the order of 2 to 4 times greater than that of the heat exchanger 7 and that the diameter of the Helmholtz volume is itself 2 to 4 times greater than that of the tube 18, the spacing between the fins may be substantially increases. Therefore, such exchanger is much less sensitive to fouling by soot or other combustion residues than conventional small Stirling exchangers. If necessary, it can easily be cleaned and is therefore particularly well suited to systems operating with solid fuels or biomass.
• FIG. 13 shows a configuration in which the tubular resonator 18 is integrated in a high temperature solar collector.
• the tube 18 of the resonator is put in the form of a helix, placed inside a cylindrical or conical cavity 28.
• One end of this tubular resonator 18 opens in a volume of Helmholtz 19, while that the other end communicates with the expansion volume V E of the Stirling engine, of which the transfer piston 6 and the regenerator 9 have been shown.
• FIG. 15 simply shows two pairs of Stirling engines whose compression volumes V CA V CB / respectively V C c / V CD / alternatively the expansion volumes V EA , V EB , respectively V EC , V ED , are connected by two tubular resonators T x , respectively T 2 , while the compression volumes V CA and V c on the one hand, and the compression volumes V CB and V CD / on the other hand, alternatively the volumes of expansion V EA and V EC on the one hand and the expansion volumes V EB and V ED , on the other hand, are connected to each other by connecting tubes T C ⁇ and T c2 whose role is to ensure that the pressures of the compression volumes, alternately of expansion, thus connected are the same since the motors arranged diagonally are in phase.
• Figure 16 shows two Stirling engines illustrated by their only compression volumes V C ⁇ , V C u, alternately their expansion volumes V E ⁇ , V E n connected by a tubular resonator 18.
• FIG. 17 shows the heating of a tubular resonator 18 connecting two Stirling engines as illustrated by FIGS. 14 to 16, arranged in a heating enclosure 26.
• the respective ends of the tube 18 of this resonator communicate with the expansion volumes V E ⁇ , V EII of two Stirling engines.
• the tube 18 of the resonator common to these two motors also constitutes a heating element common to these two motors. It would also be possible to use several resonance tubes 18 in parallel in order to increase the exchange surface and improve the heat transfer.
• the resonance tube used Since in this operating mode, the resonance tube used is entirely passive, it can only operate if it is supplied with energy by the Stirling cycle. This implies that for a cryogenic machine, the section a E of the transfer piston 6, 6a delimiting the expansion volume V E is smaller than the section a c of this transfer piston 6, 6a delimiting the compression volume V c .
• the ratio of these two sections a E / a c determines the lowest temperature level which can theoretically be reached.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Engine Equipment That Uses Special Cycles (AREA)
• Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
• Control Of Multiple Motors (AREA)
• Control Of Electric Motors In General (AREA)

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• 1999
  • 1999-04-07 EP EP99810286A patent/EP1043491A1/de not_active Withdrawn
• 2000
  • 2000-04-05 WO PCT/CH2000/000199 patent/WO2000061936A1/fr active IP Right Grant
  • 2000-04-05 EP EP00912325A patent/EP1165955B1/de not_active Expired - Lifetime
  • 2000-04-05 AT AT00912325T patent/ATE301773T1/de not_active IP Right Cessation
  • 2000-04-05 DE DE60021863T patent/DE60021863T2/de not_active Expired - Fee Related
• 2001
  • 2001-10-05 US US09/972,263 patent/US6510689B2/en not_active Expired - Fee Related

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