Scissor type compression and expansion machine used in a thermal energy recuperation system

Abstract

A compression and expansion machine is disclosed that includes a body with at least one chamber about an axis of symmetry, and pistons rotating about the axis of symmetry and dividing the chamber into cells rotating with the pistons. The invention also includes a device for coordinating the movement of the pistons and configured so that, during one rotation cycle, each of the cells performs at least one first expansion/contraction cycle corresponding to a stage of compressing a first stream of gas passing through this cell and at least one second expansion/contraction cycle corresponding to a stage of expanding a second stream of gas passing through this cell.

Claims

1. A compression and expansion machine comprising: a body with at least one chamber about an axis of symmetry; pistons rotating about the axis of symmetry and dividing the chamber into cells rotating with the pistons; and a coordination device for coordinating the movement of the pistons, the coordination device configured so that, during one rotation cycle, each of the cells performs at least one first expansion/contraction cycle corresponding to a stage of compressing a first stream of gas passing through said each of the cells, and at least one second expansion/contraction cycle corresponding to a stage of expanding a second stream of gas passing through said each of the cells, wherein the body further comprises a gas inlet opening and a gas outlet opening for each expansion/contraction cycle of said each of the cells, and wherein a passage cross-section of the gas inlet opening of the at least one first expansion/contraction cycle is larger than a passage cross-section of the outlet opening of the at least one first expansion/contraction cycle, and a passage cross-section of the gas inlet opening of the at least one second expansion/contraction cycle is smaller than a passage cross-section of the outlet opening of the at least one second expansion/contraction cycle.

2. The compression and expansion machine as claimed in claim 1, wherein the coordination device is configured such that said each of the cells performs a same number of the at least one first expansion/contraction cycle corresponding to a stage of gas expansion as the at least one second expansion/contraction cycle corresponding to a stage of gas compression.

3. The compression and expansion machine as claimed in claim 1, wherein the gas inlet opening of the at least one first expansion/contraction cycle is close to the gas outlet opening of the at least one second expansion/contraction cycle.

4. The compression and expansion machine as claimed in claim 1, wherein the gas outlet opening of the at least one first expansion/contraction cycle is close to the gas inlet opening of the at least one second expansion/contraction cycle.

5. The compression and expansion machine as claimed in claim 1, wherein the gas inlet opening of the at least one first expansion/contraction cycle and the gas outlet opening of the at least one second expansion/contraction cycle are diametrically opposed relative to the gas inlet opening of the at least one second expansion/contraction cycle and the gas outlet opening of the at least one first expansion/contraction cycle respectively.

6. The compression and expansion machine as claimed in claim 1, wherein the passage cross-section of the gas inlet opening of the at least one first expansion/contraction cycle and the passage cross-section of the gas outlet opening of the at least one second expansion/contraction cycle is larger than the passage cross-section of the gas outlet opening of the at least one first expansion/contraction cycle and the passage cross-section of the gas inlet opening of the at least one second expansion/contraction cycle.

7. The compression and expansion machine as claimed in claim 1, comprising two pairs of pistons, wherein each of the cells, during the one rotation cycle, performs only one of the at least first expansion/contraction cycle, and only one of the at least second expansion/contraction cycle, an intake stage of the at least one first expansion/contraction cycle on one of the cells having a time period common to an exhaust stage of the at least one second expansion/contraction cycle on the other cell which follows the one of the cells in the rotation cycle.

8. The compression and expansion machine as claimed in claim 7, wherein the intake stage of the at least one first expansion/contraction cycle on one of the cells is offset in time relative to the exhaust stage of the at least one second expansion/contraction cycle on the other cell which follows the one of the cells in the rotation cycle.

9. The compression and expansion machine as claimed in claim 1, wherein the coordination device comprises means for coordinating the movement of the pistons are fluidically separated from the chamber.

10. The compression and expansion machine as claimed in claim 1, further comprising sealing means between the pistons and an inner wall of the chamber to separate said each of the cells and allow dry friction on the inner wall of the chamber.

11. The compression and expansion machine as claimed in claim 1, wherein a cross-section of the chamber on an axial plane is rounded.

12. A device for recovering energy from a hot thermal source, said device comprising: a heat exchanger between a working fluid and the hot thermal source; and a compression and expansion machine comprising: a body with at least one chamber about an axis of symmetry; pistons rotating about the axis of symmetry and dividing the chamber into cells rotating with the pistons; and a coordination device for coordinating the movement of the pistons, the coordination device configured so that, during one rotation cycle, each of the cells performs at least one first expansion/contraction cycle corresponding to a stage of compressing a first stream of gas passing through said each of the cells, and at least one second expansion/contraction cycle corresponding to a stage of expanding a second stream of gas passing through said each of the cells, wherein the body further comprises a gas inlet opening and a gas outlet opening for each expansion/contraction cycle of said each of the cells, and wherein a passage cross-section of the gas inlet opening of the at least one first expansion/contraction cycle is larger than a passage cross-section of the outlet opening of the at least one first expansion/contraction cycle, and a passage cross-section of the gas inlet opening of the at least one second expansion/contraction cycle is smaller than a passage cross-section of the outlet opening of the at least one second expansion/contraction cycle wherein, at a given instant, the working fluid of the compression and expansion machine returns to the heat exchanger after having undergone the stage of compressing in the at least one first expansion/contraction cycle of the compression and expansion machine and leaves the heat exchanger in order to undergo the stage of expanding in the at least one second expansion/contraction cycle of the compression and expansion machine.

13. The device for recovering energy from a hot thermal source as claimed in claim 12, wherein an entire stream of the working fluid passing through one of the at least one first expansion/contraction cycle is processed by only one of the at least one second expansion/contraction cycle of the compression and expansion machine.

14. The device for recovering energy from a hot thermal source as claimed in claim 12, wherein one expansion/contraction cycle is open to ambient atmosphere.

15. The device for recovering energy from a hot thermal source as claimed in claim 12, wherein exhaust gases of an internal combustion engine form the hot thermal source.

16. A compression and expansion machine comprising: a body with at least one chamber about an axis of symmetry; two pairs of pistons rotating about the axis of symmetry and dividing the chamber into cells rotating with the pistons; and a coordination device for coordinating the movement of the pistons, the coordination device configured so that, during one rotation cycle, each of the cells performs at least one first expansion/contraction cycle corresponding to a stage of compressing a first stream of gas passing through said each of the cells, and at least one second expansion/contraction cycle corresponding to a stage of expanding a second stream of gas passing through said each of the cells, wherein each of the cells, during the one rotation cycle, performs only one of the at least first expansion/contraction cycle, and only one of the at least second expansion/contraction cycle, an intake stage of the at least one first expansion/contraction cycle on one of the cells having a time period common to an exhaust stage of the at least one second expansion/contraction cycle on the other cell which follows the one of the cells in the rotation cycle.

Description

DESCRIPTION OF THE DRAWINGS AND OF THE INVENTION

(1) The present invention will be better understood and further details, characteristics and advantages of the present invention will appear more clearly from reading the description which follows, with reference to the attached drawings on which:

(2) FIG. 1 shows diagrammatically the installation of a system according to the invention for recovering energy from the exhaust gases of an internal combustion engine.

(3) FIG. 2 shows diagrammatically a perspective view of a first embodiment of a scissor-type piston machine according to the invention.

(4) FIG. 3 shows diagrammatically a side view of a second embodiment of the scissor-type piston machine according to the invention.

(5) FIG. 4 shows diagrammatically a side view of a third embodiment of the scissor-type piston machine according to the invention.

(6) FIG. 5 shows diagrammatically the function of a scissor-type piston machine according to the invention in an energy recuperation system.

(7) The invention concerns a scissor-type rotating piston machine designed to be used in an energy recuperation system by causing a fluid to work in a cycle comprising stages of intake, compression, heating and expansion, and exhaust, as has been explained above. The exemplary embodiment of the invention is presented in the context of integration in a motor vehicle powered by an internal combustion engine, for recovery of the energy dissipated by the exhaust gases. However, the applicant does not intend to limit the scope of his invention to this context, since it is easy to transpose the type of heat source or energy recovered to other installations.

(8) The exemplary system shown diagrammatically in FIG. 1 uses air as a working fluid in an open cycle. The air is drawn in under ambient atmospheric conditions before being compressed and then expelled to atmosphere after expansion. As has been explained above, this choice is advantageous in terms of integration in the vehicle but does not exclude the choice of a closed cycle with cooling of the working fluid in other installations.

(9) The exemplary system described here comprises: a heat source formed by the exhaust gases circulating in the exhaust pipe 1 and originating from the internal combustion engine 2; a heat exchanger 3 between these exhaust gases and the air, which is placed on the exhaust pipe 1; a compression and expansion machine 4, performing firstly compression of the air entering the exchanger 3 and secondly expansion of the hot air leaving the exchanger 3; conduits 5 for circulating the compressed air from the machine 4 towards exchanger 3, and conduits 6 for returning the air heated in the exchanger 3 to the machine 4; conduits 7 for drawing in ambient air to the machine 4, and conduits 8 for expelling the worked air to atmosphere; a drive and energy recuperation system 9.

(10) In the embodiment shown on the figure, the drive and energy recuperation system 9 is a means of mechanical transmission between the shaft 10 of the compression and expansion machine 4, and the shaft 11 of the engine driving the vehicle, and is intended to recover the excess torque supplied by the shaft 10. In a variant, the system 9 may be an electric motor connected to the shaft 10 of the machine 4 and intended to operate as a generator under the action of the shaft 10.

(11) According to a first embodiment, with reference to FIG. 2, the scissor-type piston machine comprises a hollow body 12a forming a cylindrical chamber 12 of circular cross-section around an axis L-L.

(12) The hollow body comprises four slots forming openings 16, 17, 18, 19 in the chamber 12. On the example, these openings are made on the outer wall of the chamber 12. They may be segmented, here into three orifices, over the length of the chamber 12 along the rotation axis, as shown on FIG. 2. They have an angular extension defined around the rotation axis and are arranged in pairs.

(13) On the example, with reference to FIG. 2 and turning counter-clockwise: a first opening 16 is situated at the bottom and is intended to be connected to the conduit 7 drawing in ambient air, a second opening 17 is situated at the top, substantially vertically above the first opening 18, and is intended to be connected to the conduit 5 sending the air to the exchanger 3, a third opening 18 is also situated at the top, close to the second opening 17, and is intended to be connected to the conduit 6 carrying the air leaving the exchanger 3, a fourth opening 19 is situated at the bottom, substantially vertically below the third opening 18 and close to the first opening 16, and is intended to be connected to the conduit 8 expelling the air to atmosphere.

(14) Four pistons 14a, 14b, 14c, 14d rotating about axis L-L are installed inside the chamber 12. They are configured to each occupy a portion of angular sector, of a given angle, between the outer cylindrical wall of the chamber 12 and an inner cylindrical surface 13 of circular cross-section transversely to the axis of rotation L-L.

(15) These pistons are grouped into two diametrically opposed pairs of pistons. The pistons of each pair are integral. However, the two piston pairs may rotate around the axis differently, moving away or drawing closer. In this way, the four pistons in pairs define, between the outer wall of the chamber 12 and the inner surface 13, four cells 15a, 15b, 15c, 15d, the volume of which may increase or diminish.

(16) The movement of the two pairs of pistons is coordinated such that each of the four cells 15a, 15b, 15c, 15d undergoes two expansion and contraction cycles when passing in front of the four openings 16, 17, 18, 19 of the chamber 12.

(17) To achieve this result, a first pair of pistons 14a, 14c is connected to a first shaft 20 which forms a portion of the inner cylindrical surface 13 over approximately half the length along the rotation axis. This first shaft 20 for example is hollow and allows the passage of the second shaft 21, which forms the cylindrical surface 13 over the second half of the length along the rotation axis, and to which the second pair of pistons 14b, 14d is fixed. In this way, the two pairs of pistons 14a-14c, 14b-14d can be driven separately in rotation by the two shafts 20, 21.

(18) The two shafts pass through a transverse face of the wall of the chamber 12 and, outside this chamber 12, are coupled together and/or to the shaft 10 leaving the scissor-type machine 4 by a device 22 coordinating their movements, which allows them to perform cycles of expansion and contraction of the cells 15a, 15b, 15c, 15d while the shaft 10 of the machine 4 performs a regular rotation movement. This device for coordinating the movement of the pistons may be implemented for example by an epicyclic gear mechanism.

(19) The point at which the shafts 20, 21 pass through the chamber 12 is equipped with a sealing means which ensures that the lubricant used for the mechanisms of the coordination device 22 of the pistons 14a, 14b, 14c, 14d does not return to the chamber 12. This therefore prevents polluting with lubricant the air which passes into the cells and is then expelled into the atmosphere.

(20) Since each piston has a shape which closely conforms to that of the inner wall of the chamber 12 and the inner cylindrical surface 13 created by the two shafts 20, 21, the four cells are theoretically separated such that the air they contain is either compressed or expanded depending on the variation in their volume when they are not passing in front of an opening 16, 17, 18, 19.

(21) However, the contact points between a piston 14a, 14b, 14c, 14d and the walls of the chamber 12 and the portion of the inner cylindrical surface 13 created by the shaft 20, 21 to which it is not connected, are movable. The tightness of a cell 15a, 15b, 15c, 15d between the pistons 14a, 14b, 14c, 14d which delimit it is advantageously ensured by sealing segments 23 placed on the surface of said piston and rubbing against the walls on which it slides.

(22) It should be noted that the friction losses in the scissor-type machine, due to the movement of the pistons 14a, 14b, 14c, 14d in the chamber, are therefore linked solely to the sliding of these segments 23 on the walls. This technology therefore induces a minimum of losses, in particular because the movements of the pistons remain tangential to the walls against which a seal must be provided.

(23) On the example of FIG. 2, the internal volume of the chamber 12 in which the pistons 14a, 14b, 14c, 14d move has the shape of a torus of rectangular section. A sealing segment 23 is therefore formed from four rectilinear portions, two following the parts of the edge of the piston sliding against the flat faces axially delimiting the chamber 12, one following the part sliding against the cylindrical face of the chamber 12, and one following the part sliding on the shaft 20, 21 which does not rotate in phase with the piston.

(24) According to a second embodiment with reference to FIG. 3, the hollow body 12a is modified such that the walls transverse to axis L-L of the chamber 12 come to rejoin, with continuity of tangent, the peripheral cylindrical wall of this chamber. Furthermore, these transverse walls connect tangentially to the inner cylindrical surface 13 formed by the outer wall of the two shafts 20, 21 to which the pistons are attached. The volume in which the pistons move therefore assumes the form of a torus of ovoid cross-section, with a rectilinear portion of the cross-section at the level of the shafts 20, 21 and the outer part.

(25) This embodiment allows the production of one-piece sealing segments which have no joint between two rectilinear portions.

(26) According to a third embodiment with reference to FIG. 4, the hollow body 12a and the outer walls of the two shafts 20, 21 are designed such that the volume in which the pistons move assumes the form of a torus of circular section. This form allows the use of sealing segments 23 of circular form. The inner surface 13 formed by the walls of the shafts 20, 21 driving the pistons is no longer cylindrical but has a revolution form created by the corresponding circle portion. This form allows a better strength of the segments and ensures a better seal between the pistons and the walls of the chamber 12.

(27) With reference to FIG. 5, with the pistons 14a, 14b, 14c, 14d turning counterclockwise, the scissor-type machine 4 causes the air to circulate discontinuously in the system by aspiration/pressure of pulses of gas corresponding to the passage of the cells 15a, 15b, 15c, 15d in front of the openings 16, 17, 18, 19 of the chamber 12.

(28) The pistons 14a, 14b, 14c, 14d are identical in size, and the two pairs of pistons 14a-14c, 14b-14d follow the same movement but out of phase. The four cells 15a, 15b, 15c, 15d therefore perform an identical cycle during a complete rotation, which is described below to show how the machine causes the air to circulate.

(29) One pair of pistons 14a-14c slows down when approaching the vertical, on FIG. 5 one of the pistons 14a being between the opening 16 for intake of ambient air and the opening 19 for expulsion to atmosphere. During this time, the other pair of pistons 14b-14d accelerates, such that the piston 14b which has just passed before the intake opening 16 catches up with the piston 14c of the first pair, placed at the top, and the piston 14d which has just passed before the opening dedicated to gas returning from the exchanger 3 catches up with the piston 14a of the first pair, situated at the bottom.

(30) In this way, the cell 15a situated between the piston 14a which has nearly stopped at the bottom, and the piston 14b which is moving away from there, draws in ambient air through the opening 16. The piston 14a situated at the bottom, by being interposed between the bottom openings 16, 19, prevents this cell 15a from drawing in external air through the return opening 19. During this time, the cell 15b situated between the piston 14c which has almost stopped at the top and the piston 14b which is approaching this point, compresses the air it contains and which has just been drawn in from the ambient air. At a given moment, although its movement is slow, piston 14c advances and clears the opening 17 for communication with the exchanger 3, and the air compressed in the cell 15b can escape towards the exchanger.

(31) In this way, with reference to FIG. 5, the machine therefore draws in ambient air at low pressure through the bottom right-hand opening 16, and expels the air at high pressure through the top right-hand opening 17.

(32) Thanks to a symmetrical mechanism, and simultaneously, the machine draws in high-pressure air from the exchanger 3 through the top left-hand opening 18, and returns the expanded air at low pressure to atmosphere via the bottom left-hand opening 19.

(33) In an offset mechanism, the instants of intake of high-pressure air from the exchanger 3 through the top left-hand opening 18, and of return of the expanded low-pressure air to atmosphere through the bottom left-hand opening 19, are offset in time. This allows an improvement in the machine efficiency. In fact the cell 15c situated between the piston 14c which has almost stopped at the top and the piston 14d which is moving away from there, is the origin of an expansion of the air it contains. This air came from the opening 18 connected to the outlet of the exchanger 3 when the top piston 14c was not blocking the air inlet opening 18.

(34) In a similar fashion to the situation between the two openings 19, 18 at the bottom, the movement of the piston 14c and its angular size are determined such that it is interposed between the outlet opening 17 for the high-pressure air and the inlet opening 18 of the heated high-pressure air. In this way, there is no mixing between the air passing through the machine 4 on the right towards the exchanger 3, and the air passing through the machine 4 on the left and leaving the exchanger.

(35) The return circuit terminates in the cell 15d situated between the piston 14a which has almost stopped at the bottom and the piston 14d which is catching up with it. By contracting, the cell 15 expels the expanded air to atmosphere through the opening 19.

(36) It could also be noted that this operating mode separates the scissor-type piston machine 4approximatelyinto a high-pressure zone in the upper half and a low-pressure zone in the lower half with reference to FIG. 5.

(37) The openings 16, 19 of the low-pressure zone are advantageously adapted to allow the same flow to pass as the corresponding openings 17, 18 which are situated in the air circuit but in the high-pressure zone of greater volumic mass. The openings 16, 19 of the low-pressure zone are therefore advantageously larger than those of the high-pressure zone, since the mass volume of air passing through them is greater. This allows a large passage flow through the scissor-type machine 4 and avoids creating parasitic load losses at the low-pressure openings.

(38) On the exemplary embodiment presented with reference to FIG. 5, a difference can be seen between the openings 16, 19 of the low-pressure zone and the openings 17, 18 of the high-pressure zone.

(39) The large size of the openings 16, 19 of the low-pressure zone relative to the angular extension of the piston 14a placed between them, allows the air intake in the cell 15a on the right and the air expulsion in the cell 15d on the left to take place simultaneously over a time period in the machine's operating cycle. This phenomenon may be useful for promoting the circulation of air and increasing the flow passing through the machine.

(40) In contrast, on the example, the relative size of the piston 14c passing at the top and the openings 17, 18 of the high-pressure zone means that, at a given moment, the piston 14c blocks all communication between one of these openings 17, 18 and any of the cells 15b, 15c passing in front of them. In this example, the phases of air intake from the exchanger 3 into a first cell 15c through the intake opening 18, and expulsion through the outlet opening 17 of the air compressed in the cell 15b which follows the first cell 15c in the rotation movement, take place at two separate successive moments. Operating variants may be considered, depending on the relative size of the openings and pistons and of the position of the openings. However, the pistons all have the same angular span.

(41) Other embodiments are also possible by varying the number of pistons and openings in the chamber 12. However, the number of pistons and openings shall a priori be a multiple of four, to ensure that each circuit drawing the air in and sending it to the exchanger corresponds to a circuit receiving the air from the exchanger and expelling it to atmosphere.

(42) The function of the energy recuperation system on start-up could begin with the scissor-type machine 4 being driven by the drive and mechanical energy recuperation system 9.

(43) When the system has begun operation, the global cycle of five periods may be described by following one of the air pulses passing through the scissor-type machine 4.

(44) In a first period, a cell 15a passing in front of the opening 16 at the bottom right draws in this air pulse taken from atmosphere by means of the conduit 7, and causes an increase in its volume at constant pressure.

(45) In a second period, the cell 15b contracts in volume while rotating, compressing this air pulse and pushing it into the conduit 5 through the opening 17. The compression may take place up to an optimal operating pressure range of between 3 and 12 bar in the automotive application presented.

(46) In a third period, this air pulse is transferred to the air/exhaust gas heat exchanger 3 via the conduit 5. The temperature rises together with the pressure due to the thermal energy supplied to the air.

(47) In the embodiment presented, the air passes through the exchanger 3 in the opposite direction to the exhaust gases inside specific conduits. This exchanger arrangement, adapted to the configuration of the exhaust pipe 1, optimizes the heat exchange for a given contact distance between the flow of exhaust gases and the stream of working air. Furthermore, the high pressure level of the air in the circuit allows a compact design of exchanger 3.

(48) In a fourth period, a heated and compressed air pulse is returned to the scissor-type machine 4 via the third conduit 6. The air enters the machine 4 through the top opening 18 and expands in a cell 15c, which increases in volume as it rotates.

(49) With reference again to FIG. 5, the expansion of the hot compressed air causes the first pair of pistons 14a-14d to rotate around axis L-L and generates a mechanical energy. The piston coordination device 22 uses part of this energy to cause a second pair of pistons 14b-14d to also move, and causes the scissor-type machine 4 to undergo the first two periods, compressing the pulses of air arriving in the exchanger. The piston coordination device 22 restores the remaining energy to the rotating shaft 10 leaving the scissor-type machine 4. The system functions in recuperation mode as soon as the energy supplied by expansion is greater than the energy from compression and the losses of the device.

(50) In the fifth period, by continuing its rotation and contracting, the cell 15d expels the air pulse towards the conduit 8 for expulsion to atmosphere through the bottom opening 19. At the end of the expansion, the pressure and temperature of the air fall. The air is evacuated towards the outside at a temperature of around 100 C.

(51) The stage of compressing the air in the machine 4 corresponds to the first two cycle periods of intake and compression, while the expansion stage corresponds to the fourth and fifth periods of expansion and exhaust.

(52) A scissor-type machine 4 may achieve pressures of the order of 3-20 bar with rotation speeds of less than 10,000 rpm.

(53) With regard to the flow rate, in the example there are four cells 15a, 15b, 15c, 15d which continuously pass in front of the openings 14a, 14b, 14c, 14d of the chamber 12. Therefore, the first period of a cycle begins immediately following the first period of the preceding cycle. It is not therefore necessary to allow a time to elapse, as in a four-stroke reciprocating piston machine. Furthermore, the four periods take place in the same chamber 12, whereas in comparison, in a reciprocating machine, one piston would be used for the intake/compression stage of the air coming from atmosphere, and one piston for the expansion/exhaust stage of the heated air. The machine is therefore much more compact than a reciprocating movement piston machine for a same flow rate.

(54) Furthermore, because of the design of air circulation in the machine, the openings may be optimized. Because these openings concern different zones of the chamber, and also because the rotating means have a continuous movement when passing in front of them, the geometry of the machine allows the passage cross-sections to be optimized. These passage cross-sections allow a reduction in load losses. In comparison with a machine using pistons with reciprocating movement, such a machine allows a gain of several factors in the flow rate with lower load losses, which improves the efficiency of the system.

(55) Also, in comparison with a blade machine which is another type of rotating volumetric machine, the configuration allows further advantages, such as better monitoring of the rate of compression and expansion of the cells, and hence equivalent performance to be obtained with a smaller volume.

(56) In a variant embodiment (not shown), intake air already compressed passes into the conduit 7 to be drawn into a cell 15a during the first period of the cycle, which allows a reduction in the size of the machine for the same performance. For example, the compressed air may be taken from a turbocompressor which uses the exhaust gases as a source for driving the compressor in rotation.

(57) In another variant embodiment (not shown), the intake aireither ambient air or compressed airis first cooled before entering the machine via an intake air cooler for example, which allows a reduction in the temperature of the working fluid entering the exchanger, and hence an increase in efficiency of the energy recuperation device.

(58) In fact, to operate optimally, the temperature of the working fluid on entry to the exchanger must be lower than the temperature of the heat source circulating in the exchanger.

(59) In the context of an application to a vehicle powered by an internal combustion engine, the system will be furthermore advantageously adapted to the variations in engine speed or atmospheric conditions, for example by introducing bypass-type systems on the air circuit and on the exhaust pipe for the engine gases upstream of the heat exchanger, in order to adapt the flow rates to the energy which may be recovered. Also, in a variant, with a view to optimizing efficiency, additional cooling of the rotating volumetric machine by a water or air circuit or by fins may prevent excessive heating thereof from friction and from the working fluid coming from the exchanger.