Electric energy generating device

Abstract

Electric energy generating device (1) for installation to an exhaust conduit (2) in which an exhaust gas (9) is flowing, comprising: a thermoelectric generator (3) comprising a hot side (4) and a cold side (5), at least one hot side heat transfer loop (6) comprising a fluid conduit circuit having a thermal fluid circulating therein, and where the fluid conduit circuit comprises: a first in section (7) n thermal contact with the hot side (4), a second section (8) adapted to be in thermal contact with the exhaust gas (9), a third section (10) and a fourth section (11), wherein the third section (10) and the fourth section (11) each comprises at least one vibrational damping part (12), wherein each of the at least one vibrational damping part (12) comprises a heat resistant and flexible tube integrated into the third section (10) and the fourth section (11) of the fluid conduit circuit.

Claims

1. An electric energy generating device for installation to an exhaust conduit in which an exhaust gas is flowing, characterised in that the device comprises; a thermoelectric generator comprising a hot side and a cold side, at least one hot side heat transfer loop comprising a fluid conduit circuit having a thermal fluid circulating therein, and where the fluid conduit circuit comprises; a first section in thermal contact with the hot side of the thermoelectric generator, a second section adapted to be in thermal contact with the exhaust gas, a third section located between the first section and the second section upstream of the first section and a fourth section located between the first section and the second section downstream of the first section, wherein the third section and the fourth section are thermally insulated, and each comprise: at least one vibrational damping part, wherein each of the at least one vibrational damping part comprises a heat resistant and flexible tube integrated into the third section and the fourth section of the fluid conduit circuit, and at least one connection device to connect the third section and the fourth section to a surface external to the device and the exhaust conduit, wherein each of the at least one connection device comprises a vibrational damping portion, at least one cold side heat transfer loop arranged on the cold side of the thermoelectric generator, the at least one cold side heat transfer loop being in thermal communication with a cooling reservoir.

2. The device according to claim 1, wherein the fluid conduit circuit comprises a control valve.

3. The device according to claim 1, wherein the third section and fourth section are adapted to be arranged externally to the exhaust conduit.

4. The device according to claim 1, wherein the at least one hot side heat transfer loop is a heat pipe.

5. The device according to claim 4, wherein the first section is arranged above the second section.

6. The device according to claim 1, wherein the second section is adapted to be arranged externally to the exhaust conduit.

7. The device according to claim 6, wherein the second section is in thermal contact with at least one heat exchanging element, the heat exchanging element being adapted to extend internally into the exhaust conduit, such that the at least one heat exchanging element is directly exposed to the exhaust gas.

8. The device according to claim 1, wherein at least one first part of the second section is adapted to extend internally into the exhaust conduit, such that the at least one first part of the second section is directly exposed to the exhaust gas.

9. The device according to claim 8, wherein the surface of the second section's at least one first part comprises any of: plates, fins, turbulator wires and heat pipes.

10. The device according to claim 1, wherein at least one second part of the second section is adapted to any of: lie inside a wall of the exhaust conduit and lie against an external wall of the exhaust conduit, such that the at least one second part is not directly exposed to the exhaust gas.

11. The device according to claim 1, wherein at least one turbulence inducing device is arranged on an internal wall of the exhaust conduit adjacent or directly upstream to the second section.

12. The device according to claim 1, wherein the at least one cold side heat transfer loop comprises a fluid pumping device for circulating a thermal fluid contained in the loop.

13. The device according to claim 1, wherein the cooling reservoir is adapted to be arranged in thermal communication with a heat exchanger external to the device.

14. A system for generating electric power from the exhaust of a combustion engine, comprising at least one electric energy generating device according to any of the preceding claims.

15. The system according to claim 14, comprising a heat exchanger in thermal communication with the cooling reservoir of the device.

16. The system according to claim 14, where several electric energy generating devices are arranged substantially longitudinally parallel and/or substantially in a downstream extending series in the exhaust conduit.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 schematically illustrates an aspect of the invention, where an electric energy generating device is installed in an exhaust conduit.

(2) FIG. 2 schematically illustrates an aspect of the invention, where an electric energy generating device is installed in an exhaust conduit with a second section running along the conduit wall.

(3) FIG. 3 schematically illustrates an aspect of the invention, where an electric energy generating device comprises a plurality of heat transfer loops.

(4) FIG. 4 schematically illustrates an aspect of the invention, where a system for generating electric power from the exhaust of a combustion engine, comprises two electric energy generating devices in an exhaust conduit of a system exemplified as a ship.

(5) FIG. 5 schematically illustrates an aspect of the invention, where an electric energy generating device comprising a heat pipe is arranged above an exhaust gas conduit, and where the third section comprises a control valve connected to the second section.

(6) FIG. 6 schematically illustrates an aspect of the invention, where an electric energy generating device comprising a heat pipe is arranged above an exhaust gas conduit, and where the fourth section comprises a control valve connected to the second section.

(7) FIG. 7 schematically illustrates an aspect of the invention, where an electric energy generating device comprising a heat pipe is arranged above an exhaust gas conduit, and where the third section comprises a control valve connected to the third section.

(8) FIG. 8 is a perspective view of two systems comprising a plurality of thermoelectric generators arranged gravitationally above two exhaust conduits.

DETAILED DESCRIPTION OF THE INVENTION

(9) The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings.

(10) In FIG. 1 an aspect of the invention is shown where an electric energy generating device 1 is installed in an external system 18 (see FIG. 4 where the external features are represented by dashed lines). A thermoelectric generator 3 is thus shown in an aspect where the generator 3 is installed in connection with an exhaust conduit 2. A heat transfer loop 6 runs from a hot side 4 of the generator 3 and through the inside of the exhaust conduit 2 so that the loop is exposed to exhaust gases 9. Another heat transfer loop 13 is arranged on an opposite, cold side 5 of the generator 3, and runs through a cooling reservoir 14. Both the hot side heat transfer loop 6 and the cold side heat transfer loop 13 comprise a fluid conduit circuit containing a thermal fluid. The fluid conduit may comprise any pipe, tube or other suitable conduit as will be apparent to the skilled person based on the disclosure of the invention herein. The hot side heat transfer loop 6 is partitioned into four sections; a first section 7 arranged on the hot side of the thermoelectric generator 3, a second section 8 on the opposing side of the loop 6 at a distance away from the generator 3 and adapted to be arranged inside an exhaust conduit 2, a third section 10 and a fourth section 11 extending between the first section 7 and the second section 8.

(11) When thermal fluid is circulated in the heat transfer loop 6 it will circulate from the second section 8 via the third section 10 to the first section 7 and then back to the second section 8 via the fourth section 11. The third section 10 is arranged upstream of the first section 7 and the fourth section 11 is arranged downstream of the first section 7. Consequently, in the heat transfer loop 6 the third and fourth sections 10, 11 separate the first section 7 from the second section 8.

(12) The thermal fluid inside the hot side heat transfer loop 6 absorbs heat when running through the second section 8, which is exposed to warm exhaust gases 9, and transports this heat to the hot side 4 of the thermoelectric generator 3 where the fluid is cooled down. The fluid in the hot side heat transfer loop 6 is cooled as heat is conducted across the thermoelectric generator 3 to the cold side 5.

(13) Simultaneously, the thermal fluid inside the cold side heat transfer loop 13 absorbs heat when running past the cold side 5 of the thermoelectric generator 3, and transports the heat to a cooling reservoir 14 where the fluid is cooled before being circulated back to the generator 3 again. Thus, a temperature gradient is sustained across the thermoelectric generator 3, which consequently produces an electric current. To improve the circulation of the thermal fluid, pumps 16, 17 may be arranged on the heat transfer loops 6, 13 as illustrated in the figures. The location of the pumps 16, 17 may be in any suitable location along the loops 6, 13, as will be obvious to the person skilled in the art based on the description of the invention herein. An expansion tank, or receiver tank 23 is also illustrated in FIGS. 2 and 3, the location of the expansion tank 23 also being at any suitable place along the loops 6, 13.

(14) The second section 8 is exemplified with a substantially spiraled shape extending into the interior of the exhaust conduit 2 in FIGS. 1 and 3, though the shape may vary according to what is most suited to the existing exhaust conduit 2. Though not illustrated herein, the second section 8 may be arranged with an outer surface comprising turbulence inducing devices and shapes, such as fins, turbulator wires, heat pipes, roughened surface, ridges and other means to disrupt the formation of a boundary layer of exhaust gas 9 and create a greater area of the surface exposed to exhaust gas 9. To prevent the formation of an insulating layer of particles on the second section 8, such as soot, the second section's 8 outer surface comprises a catalytic layer.

(15) The hot side heat transfer loop 6 is thermally insulated to prevent heat loss to the external surroundings. To protect the thermoelectric generator 3 from vibrations propagating through the third section 10 and fourth section 11 of the hot side heat transfer loop 6, vibrational damping parts 12 are arranged along these sections 10, 11.

(16) The vibrational damping parts 12 may comprise a heat resistant and flexible tube, and may as an example extend along the entire third section 10 and fourth section 11 respectively. Alternatively the vibrational damping 12 part may constitute 5% to 100%, e.g. 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100%, of the length of the third 10 or fourth section 11 respectively. The heat resistant and flexible tube may as an example comprise a convoluted core with a wire over braid, the core being produced from stainless steel or nickel alloy sheet with annular or spiral convolutions, though any similar heat resistant and flexible tube may be used as will be apparent to the person skilled in the art based on the disclosure of the invention herein. In certain aspects of the invention, for example on ships exhaust systems, the vibrational damping part may comprise metallic flexible hoses such as the ones marketed by Belman.

(17) Illustrated by the dashed line, an external heat exchanger 15 can be arranged to transport heat away from the cooling reservoir 14. In another aspect, not illustrated herein, an external heat exchanger 15 may be in direct thermal communication with the cold side heat transfer loop 13. Depending on the existing exhaust system where the electric energy generating device 1 is to be installed, the device may accordingly employ the pre-existing features of the system.

(18) FIG. 2 illustrates an aspect of the invention, where the second section 8 of the heat transfer loop 6 is arranged along the wall of the exhaust conduit 2. In aspects of the invention, the second section 8 is arranged along the inside of the exhaust conduit 2 wall, integrated into the exhaust conduit 2 wall or along the outside of the exhaust conduit 2 wall. The second section 8 may in some aspects be arranged to varying degrees inside, outside or alongside the exhaust conduit 2 wall as described above, but will in all aspects be in thermal contact with the exhaust gas 9. As illustrated in FIG. 2, a turbulence inducing device 22, exemplified as a turbulator wire, is arranged alongside the second section 8 on the inside of the exhaust conduit 2 wall. The turbulence inducing device 22 may be arranged substantially parallel or upstream to the second section 8, as its purpose is to disrupt a laminar boundary layer of exhaust gas 9 along the wall of the exhaust conduit 2.

(19) Exemplified in FIG. 2, two connection devices 20 are connected to the third section 10 and the fourth section 11 respectively, the connection devices 20 connecting the sections 10, 11 to a surface via a vibrational damping portion 21. The connection devices 20 in FIG. 2 are merely represented for illustrative purposes, and may comprise a clamp or any other similar devices suited to fasten and hold the sections 10, 11, with a spring, flexible body or similar suited device comprising the vibrational damping portion 21.

(20) In other aspects of the invention, a single connection device 20 may connect both the third section 10 and the fourth section 11 together. Several connection devices 20 may also be arranged in parallel along the sections 10, 11. The surface onto which the connection devices 20 are fitted may be a roof, ceiling or wall external to the exhaust conduit and electric energy generating device, so as to prevent vibrations propagating to the thermoelectric generator. In some aspects, connection devices 20 may be connected to several surfaces. Dependent on the external system, the arrangement of the connection devices 20 will be adapted as will be apparent to the skilled person based on the disclosure of the invention herein.

(21) FIG. 3 illustrates an aspect of the invention, exemplified by an electric energy generating device 1 comprising two heat transfer loops 6 on a hot side 4 of the thermoelectric generator 3, the hot side heat transfer loops 6 being arranged to extend into an exhaust conduit 2. Correspondingly two heat transfer loops 13 are arranged on the cold side 5 of the thermoelectric generator 3, the cold side heat transfer loops 13 extending through a cooling reservoir 14. The number of loops is not limited to two on each side, nor does the number of loops 6, 13 on each side have to be similar. A device may have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or any higher suitable number of independent loops 6, 13 on each side of the thermoelectric generator 3.

(22) The configuration of the heat transfer loops 6, 13 is dependent on the exhaust system in which the electric energy generating device 1 is to be installed. In some cases there may be existing heat exchangers, such as economizers, installed in the exhaust conduit. In such cases the electric energy generating device 1 may be installed in connection with these existing systems, configuring the heat transfer loops 6, 13 accordingly.

(23) In one aspect of the invention, exemplified in FIG. 4, two electric energy generating devices 1 are installed in an exhaust conduit 2 of a ship. Heat exchangers are commonly found on ships and other offshore constructions, where they utilize ambient water to cool down systems on the ship via the heat exchanger. Though FIG. 4 schematically illustrates separate heat exchangers 15 for the devices 1, a plurality of devices may also be connected to a common heat exchanger 15. Dependent on the system where an electric energy generating device is to be installed, the device is configured with features that best complement the existing system.

(24) FIG. 5 illustrates an aspect of the invention, where the second section 8 of the heat transfer loop 6 comprises heat exchanging elements 25 comprising thermal plates and which are arranged to extend inside the exhaust conduit 2. The thermal fluid may typically circulate through the heat exchanging elements 25 extending into the exhaust conduit, and thus the heat exchanging elements 25 may act as evaporators, evaporating the thermal fluid and ensuring the thermal fluid in the second section 8 of the hot side heat transfer loop 6 is in thermal contact with the exhaust gas 9.

(25) FIG. 5 furthermore illustrates an aspect, where the first section 7 of the hot side heat transfer loop 6 is gravitationally arranged above the second section 8. In the example shown in FIG. 5, the exhaust gas conduit is illustrated in a horizontal direction, however the first section 7 may be arranged gravitationally above the second section 8 also where the exhaust gas conduit is not horizontal, such as vertical or arranged in any angle in-between horizontal and vertical. Notably, in such aspects, the hot side heat transfer loop 6 may comprise a heat pipe, which does not require a pumping means to circulate the fluid within. Instead, the thermal fluid evaporates as it passes the second section 8 where heat is transferred to the fluid, whereupon the fluid rises to the first section 7 where it gives off heat to the thermoelectric generator 3 and condenses as a result. The condensed thermal fluid will then flow back down to the second section 8 again, and the process repeats.

(26) An aspect of the invention is exemplified in FIG. 5, where a control valve 24 is arranged on the hot side heat transfer loop 6. The control valve is typically arranged between the second section 8 and the first section 7. In the aspect illustrated in FIG. 5, the control valve 24 is arranged on the third section, i.e. downstream of the second section 8 where the thermal fluid has been heated by the exhaust gas 9. A control unit 26 is coupled to the second section 8, and may for example actuated by temperature such as a thermostat, a spring based pressure valve or a combination as is known in the art. When the control unit 26 actuates the valve 24, to decrease or shut down volume flow through the third section 10, pressure will build up in the second section 10 which will result in liquid in the receiver tank 23 being pushed back into the first section 7 and thereby provide additional cooling to the hot side 4 of the thermoelectric generator.

(27) Another aspect of the invention is exemplified in FIG. 6, where the control valve 24 is arranged on the fourth section, i.e. upstream of the second section 8. A control unit 26 is coupled to the second section 8, and which when actuated, causes a buildup of pressure and thereby liquid in the first section 7 such that thermal resistance increases.

(28) Another aspect of the invention is exemplified in FIG. 7, where the control valve 24 is arranged on the third section. In this aspect, a control unit 26 is coupled to the third section downstream of the control valve 24. Thus, when actuating the control valve 24, the flow of thermal fluid into the first section 7 may be controlled thereby controlling the temperature of the hot side 4 of the thermoelectric generator directly.

(29) FIG. 8 is a perspective view of an example of the invention, where two systems comprising a plurality of thermoelectric generators are installed on two exhaust conduits 2. As with the examples in FIGS. 5-7, the example in FIG. 8 illustrates the thermoelectric generators 1 and the first section 7 arranged gravitationally above the second section 8, such that the thermal fluid may evaporate in the heat exchanging elements 25, rise up to the first section 7 and condense before draining back down to the second section again. Although the thermoelectric generators 1, and the heat exchanging elements 25 are exemplified as being arranged in a vertical orientation, it should be noted that a horizontal orientation is also possible, and that they may be arranged in different locations and also on vertical exhaust conduits 2, though this is not illustrated herein.

(30) The invention is herein described in non-limiting embodiments and variations. A person skilled in the art will understand that there may be made alterations and modifications to the embodiments and variations that are within the scope of the invention as described in the attached claims.

REFERENCE SIGNS LIST

(31) 1. Electric energy generating device 2. Exhaust conduit 3. Thermoelectric generator 4. Hot side of generator 5. Cold side of generator 6. Hot side heat transfer loop 7. First section of loop 8. Second section of loop 9. Exhaust gas 10. Third section of loop 11. Fourth section of loop 12. Vibrational damping parts 13. Cold side heat transfer loop 14. Cooling reservoir 15. Heat exchanger 16. Fluid pumping device hot side loop 17. Fluid pumping device cold side loop 18. System for generating electric power 19. Combustion engine 20. Connection device 21. Connection device vibration damping portion 22. Turbulence inducing device 23. Expansion tank 24. Control valve 25. Heat exchanging element 26. Control unit