FR3049649A1 - INTERNAL COMBUSTION ENGINE COMPRISING A THERMOACOUSTIC SYSTEM - Google Patents

Abstract

Internal combustion engine (2) having an exhaust manifold (31), a cooling circuit (5) in which a coolant, a radiator (15) circulates, and a system (20) thermoacoustic device comprising: - a resonator (21) comprising a gas under pressure, - an emitter (29) of acoustic waves capable of producing an acoustic wave inside the resonator, - at least two thermoacoustic modules (24, 25) arranged inside the resonator, the two modules being respectively composed of a porous structure (26) bordered by a heat exchanger (27) and a cold heat exchanger (28), wherein the heat exchanger of the first thermoacoustic module is connected a radiator circuit (8) extending the cooling circuit through a water outlet housing (6) and joining the radiator, the hot heat exchanger of the second module being connected to the exhaust manifold.

Description

INTERNAL COMBUSTION ENGINE COMPRISING A THERMOACOUSTIC SYSTEM

The invention relates to thermoacoustic machines. The invention also relates to vehicles, in particular automobiles, comprising a thermoacoustic machine.

[0002] A thermoacoustic machine is a thermoacoustic-electrical (or thermo-acousto-mechanical) converter, which first amplifies an acoustic wave via the thermal, and can either amplify acoustic energy from the consumption of a a certain amount of heat, or consume acoustic energy to pump heat from a cold environment to a warm environment.

[0003] Thermoacoustic machines are cyclic thermal machines exchanging energy with external sources in the form of work and heat, the work being of an acoustic nature. In these machines, the interaction of thermal and acoustic oscillations of a fluid in the vicinity of solid walls subjected to a high temperature gradient generates an amplification of the acoustic wave via the thermal.

[0004] Conventionally, thermoacoustic stationary wave machines ("standing-wave thermoacoustic System" in English) and thermoacoustic machines of Stirling, known as "traveling-wave thermoacoustic System", are conventionally distinguished.

Stationary wave thermoacoustic machines comprise a waveguide, a stack of plates (called stack), and heat exchangers, typically two exchangers placed on either side of the stack. Stationary wave thermoacoustic motors are thermally modeled by a Brayton cycle.

[0006] The traveling wave thermoacoustic machines comprise a waveguide, a stack of plates (referred to as a regenerator) and heat exchangers. The traveling wave thermoacoustic motors are thermally modeled by a Stirling cycle.

The assembly formed by two heat exchangers placed on either side of a stack or regenerator is often called acoustic amplification cell.

The stack (stack or regenerator) is made of a material having a high heat capacity and low thermal conductivity, for example stainless steel, composite material, ceramic. The stack is conventionally formed of fine grids or stainless steel plates, other geometries having been proposed (for example carbon foams, steel plate winding).

[0009] For a general presentation of the thermoacoustic machines, reference can be made to the document Jin et al, Thermoacoustic prime movers and refrigerators: Heat-powered engines without moving components, Energy 93, pp. 828-853, 2015.

It has rarely been proposed in the prior art to recover the thermal energy of a hot gas by a thermoacoustic machine. The document Tijani et al (Applied Thermal Engineering, pp. 866-870, 2013) describes the recovery of thermal energy from an air flow at 620 ° C. by a Stirling thermoacoustic machine. The document Haddad et al (Energy Efficiency Solutions to Recover Low and Medium Waste Heat: Competitiveness of the Thermoacoustic Technology, Energy Procedia 50, pp. 1056-1069, 2014) describes the recovery of thermal energy from engine exhaust gases. with internal combustion using a thermoacoustic machine with three acoustic amplification cells placed in series, the energy being converted into electricity.

JP2009216045 discloses a system for recovering the energy at the exhaust of an engine. When the engine is cold, a heat exchanger is operated and controlled, a thermoacoustic device being operated in a heat pump mode. When the engine is warm, the thermoacoustic device is operated and managed in a motor mode.

The system described in JP2009216045 does not go without drawbacks. In particular, the need for rapid rise in engine temperature requires the use of an exhaust thermal recovery device (RTE).

A first objective is to propose a thermoacoustic system arranged in an engine, using as a hot source engine exhaust gas and comprising a means for ensuring a rapid rise in engine temperature.

A second objective is to provide a thermoacoustic system arranged in an engine, using as a hot source engine exhaust gas and comprising a means increasing the total efficiency of the thermoacoustic system.

For these purposes, it is proposed, in the first place, an internal combustion engine provided with a cylinder block having a plurality of cylinders, an exhaust manifold, a cooling circuit in which circulates a coolant, a radiator, and a thermoacoustic system comprising: - a resonator comprising a gas under pressure, - an acoustic wave emitter, capable of producing an acoustic wave inside the resonator, - at least two thermoacoustic modules, arranged inside the resonator, the two modules being respectively composed of a porous structure bordered by a hot exchanger and a cold exchanger, and allowing to pass the acoustic wave and amplify its acoustic energy, a power converter capable of converting the acoustic energy of an acoustic wave into electrical energy, in which the hot heat exchanger of the first thermoacoustic module is connected to a circulator a radiator extending the cooling circuit through a water outlet housing and joining the radiator, the hot heat exchanger of the second module being connected to the exhaust manifold.

Such an engine includes a thermoacoustic system for recovering the thermal energy of the engine at its output for reuse.

This thermoacoustic system makes it possible to manage the speed of temperature rise of the engine according to the needs.

Various additional features may be provided, alone or in combination: the engine comprises a passenger compartment heating circuit extending the cooling circuit through the water outlet housing, comprising a nozzle and a cabin heating unit; the engine comprises a recirculation circuit extending the cooling circuit through the water outlet housing; - The radiator circuit comprises a first bifurcation implemented by means of a solenoid valve and a hydraulic connector, adapted to avoid the use of the radiator; - The radiator circuit comprises a second bifurcation implemented by means of two solenoid valves, adapted to conduct the cooling liquid directly to the first bifurcation without passing through the hot heat exchanger of the first module; the cold exchangers of the thermoacoustic modules are connected to an auxiliary cooling circuit, in which a coolant circulates, comprising an auxiliary pump; the auxiliary cooling circuit is connected to the inlet and the outlet of the radiator by means of two hydraulic connections; an auxiliary heat exchanger is arranged between the radiator outlet and the auxiliary pump; the auxiliary cooling circuit is separated into two flows by means of a hydraulic connection disposed between the cold exchanger of the first module and the cold exchanger of the second module; an auxiliary heat exchanger is arranged in parallel with the radiator by means of two solenoid valves; the passenger compartment heating circuit comprises two solenoid valves arranged at the inlet and the outlet of a cabin heating unit and the auxiliary cooling circuit comprises a solenoid valve, so as to join the exit of the cabin heating unit to the radiator inlet and join the inlet of the heating unit to the auxiliary cooling circuit; the cooling circuit, the passenger compartment heating circuit and the auxiliary cooling circuit respectively comprise a solenoid valve, so as to conduct the coolant of the cooling circuit annexed to the cooling circuit, and so as to conduct the coolant in output of a cabin heating unit to the auxiliary cooling circuit, between the cold exchanger of the first module and the cold exchanger of the second module.

It is proposed, secondly, a motor vehicle comprising an internal combustion engine as presented above.

Other features and advantages of the invention will appear more clearly and concretely on reading the following description of embodiments, which is made with reference to the accompanying drawings, in which: FIG. a perspective view of a motor vehicle (in broken lines) including an internal combustion engine (in solid bold lines); FIG. 2 is a schematic view of the internal combustion engine of FIG. 1 comprising a thermoacoustic system; FIG. 3 is a schematic view of a thermoacoustic module; FIG. 4 is a schematic view of the internal combustion engine of FIG. 1 comprising a thermoacoustic system according to a first embodiment; FIG. 5 is a schematic view of the internal combustion engine of FIG. 1 comprising a thermoacoustic system according to a second embodiment; FIG. 6 is a graph illustrating the temperature in an auxiliary cooling circuit of the thermoacoustic system of FIG. 1 as a function of the speed of the motor vehicle; FIG. 7 is a schematic view of the internal combustion engine of FIG. 1 comprising a thermoacoustic system according to a third embodiment; FIG. 8 is a schematic view of the internal combustion engine of FIG. 1 comprising a thermoacoustic system according to a fourth embodiment; FIG. 9 is a schematic view of the internal combustion engine of FIG. 1 comprising a thermoacoustic system according to a fifth embodiment; FIG. 10 is a schematic view of the internal combustion engine of FIG. 1 comprising a thermoacoustic system according to a sixth embodiment; - Figure 11 is a schematic view of the internal combustion engine of Figure 1 comprising a thermoacoustic system according to a seventh embodiment; FIG. 12 is a schematic view of the internal combustion engine of FIG. 1 comprising a thermoacoustic system according to an eighth embodiment; FIG. 13 is a schematic view of the internal combustion engine of FIG. 1 comprising a thermoacoustic system according to a ninth embodiment; - Figure 14 is a schematic view of the internal combustion engine of Figure 1 comprising a thermoacoustic system according to a tenth embodiment.

Figure 1 illustrates an automobile vehicle 1 comprising an internal combustion engine 2.

As illustrated in FIG. 2, the engine 2 comprises a cylinder block 3 in which a plurality of cylinders 4 is hollowed out.

Combustion takes place in the cylinders 4, following the ignition of an air / fuel mixture.

The engine 2 comprises a cooling circuit 5 supplying the cylinder block 3 in cooling liquid. This coolant, when it enters the cylinder block 3, envelops the cylinders 4 to cool, then heads to a housing 6 of water outlet.

The water outlet housing 6 makes it possible to circulate the cooling liquid at the outlet of the cylinder block 3, via three circuits: a cabin heating circuit 7, a radiator circuit, and a circuit 9 of recirculation.

The cooling circuit 5 comprises a pump 10, for conveying the cooling liquid to the cylinder block 3.

The coolant comes from both the cabin heating circuit 7, the radiator circuit 8 and the recirculation circuit 9.

The cabin heating circuit 7 is always open, and comprises a nozzle 11 for adjusting the flow rate of the coolant that passes through.

The cabin heating circuit 7 comprises a cabin heating unit 12, providing a heat exchange, for heating the air of a passenger compartment 13 of the vehicle 1, using the coolant as a hot source.

For example, the cabin heating unit 12 is placed in front of a fan blowing cold air. The heat exchange between the cold air and the coolant which is at a temperature above the temperature of the cold air blown by the fan, will warm the air of the passenger compartment 13.

Once its temperature has dropped, following its passage through the cabin heating unit 12, the coolant is conveyed at the outlet of the cabin heater unit 12 to the cooling circuit 5.

The radiator circuit 8 is powered by means of a thermostat 14, for example contained in the water outlet housing 6. For example, the thermostat 14 comprises a wax that expands when heated or is electrically controlled. The thermostat 14 makes it possible to block the coolant until it has reached a programmed temperature. Once this temperature is reached, the thermostat 14 opens and connects the cooling circuit 5 to a radiator 15.

The radiator 15 provides a heat exchanger, for evacuating the heat of the coolant to reject it to the ambient air.

The coolant passes through the radiator 15, its temperature output of the radiator 15 being lower than its inlet temperature of the radiator 15, and is then routed to the cooling circuit 5, through a casing 16 degassing , for circulating the cooling liquid under pressure and removing the gas bubbles contained in the coolant.

The radiator circuit 8 comprises a first bifurcation 17 managed by a solenoid valve 18, to adjust the flow rate as required. Thus, the coolant may not pass through the radiator 15 to directly join the cooling circuit 5. When the temperature of the coolant is low at the outlet of the cylinder block 3, the recirculation circuit 9 directly conveys the coolant to the cooling circuit 5, the thermostat 14 being in the closed position.

The circuits 7, 8, 9 comprise hydraulic connectors 19 for the junction between the circuits 7, 8, 9 and the bifurcations.

The engine 2 comprises a thermoacoustic system 20. In the embodiments shown, the thermoacoustic system 20 comprises a resonator 21 formed of a tubular body having a first end 22 and a second end 23.

The resonator 21 integrates, inside its body, two thermoacoustic modules, a first module 24 disposed near the first end 22 and a second module 25 disposed near the second end 23.

Each thermoacoustic module 24, 25 is respectively composed of a porous structure 26 (commonly called "stack") bordered by two heat exchangers, a hot exchanger 27 fed by a hot source, and a cold exchanger 28 fed by a cold source.

For example, the porous structure 26 comprises a stack of plates, forming a network of holes for the passage of a sound wave and acting as a thermal skin that diffuses heat.

A pressurized gas is confined in the resonator 21, and is excited by the application of an acoustic power, by means of a transmitter 29 of sound waves. An input acoustic wave We is thus produced at the first end 22 of the resonator 21.

The acoustic wave We moves in the porous structures 26 of each module 24, 25 thermoacoustic, it is heated on one side and then cooled on the other through all the exchangers 26, 27 of heat, and then describe a thermodynamic cycle. The acoustic wave applied to the inlet of each porous structure 26 will be amplified by the effect of the temperature.

The system 20 comprises an acoustic energy converter 30, disposed at the second end 23 of the resonator 21, for transforming the energy of the acoustic wave created in the resonator 21 into electrical or mechanical energy (using example a loudspeaker or a bi-directional turbine).

The amplification of the input acoustic wave We is defined by a factor f, it is equal to the ratio between the acoustic energy at the input of a thermoacoustic module on the acoustic energy of the wave. acoustic output W1 of the first module 24.

The factor f is proportional to the ratio between the temperature between the hot source (Tchaud) and the cold source (Tfroid) to a constant that depends on thermo-physical characteristics such as the type of gas, the viscosity of the gas, the pressure, the porosity of the porous structure.

All the thermal energy of the input acoustic wave We can not be totally transformed into acoustic energy, a part Qc must be evacuated by means of the cold exchanger 28 of each module 24, 25 to the ambient air, as shown schematically in Figure 3.

The heat exchanger 27 of the first module 24 is directly connected to the circuit 8 radiator. Thus, the coolant circulating in this radiator circuit serves as a hot source for the first module 24.

The heat exchanger 27 of the first module 24 brings thermal energy Qh to the input acoustic wave We to amplify its intensity. Thus, the intensity of the acoustic wave W1 at the output of the first module 24 will be greater than the acoustic wave We.

The engine 2 comprises an exhaust manifold 31, for discharging the exhaust gas from the combustion inside the cylinders 4. The exhaust manifold 31 advantageously comprises a treatment device (not shown ) for reducing the harmfulness of the exhaust gas, for example a particulate filter and / or a selective catalytic reduction system and / or a device for treating nitrogen oxides.

The heat exchanger 27 of the second module 25 is directly connected to the exhaust manifold 31. Thus, the engine exhaust gases serve as a hot source for the second module 25.

The heat exchanger 27 brings thermal energy Qh to the acoustic wave W1 to amplify its intensity. Thus, the intensity of the acoustic wave W2 at the output of the second module 25 will be greater than the acoustic wave W1.

Each module 24, 25 will amplify the acoustic wave from the previous module 24, 25, We becomes W1 through the first module 24, W1 becomes W2 through the second module 25. Each acoustic wave passage in the modules 24, 25 is symbolized by a black arrow in the figures.

In the embodiments shown, the thermoacoustic system 20 comprises two modules 24, 25 in series. In other embodiments, not shown, the thermoacoustic system comprises more than two modules, including more than two modules placed in series.

In some implementations, the modules 24, 25 are substantially identical. In other implementations, the modules 24, 25 have different performances, and provide different amplifications.

The acoustic system makes it possible to evacuate a large part, or even all of the thermal energy of the cooling liquid at the outlet of the water outlet housing 6, so that it is not necessary to pass the coolant by the radiator 15, hence the presence of the first bifurcation 17 on the circuit 8 radiator.

The general structure having been presented, we now describe particular embodiments.

In these particular embodiments, the heat exchange taking place at the level of the radiator 15, and at a heat exchanger 33 of annex heat, are symbolized by one or more white arrows, in Figures 4 to 14.

According to a first and a second embodiment, illustrated in FIGS. 4 and 5, the entire architecture described with reference to FIG. 2 is repeated and the thermoacoustic system 20 comprises an auxiliary cooling circuit 32, using a heat exchanger 33 annex, circulating a liquid in the circuit 32 of auxiliary cooling, by means of a pump 34 annex.

The use of a liquid instead of a gas increases the efficiency of the cold exchangers 28, the heat exchange between two liquids requiring less contact surface. It will thus be possible to reduce the size of the cold exchangers.

The first and second embodiments are identical, with one difference: in the second embodiment, illustrated in Figure 5, the radiator circuit 8 comprises a second bifurcation 35 managed by solenoid valves 18, this second bifurcation being added to the architecture presented in Figure 2.

This second bifurcation 35 keeps the thermal energy of the coolant, not using it to supply the heat exchanger 27 of the first module 24.

FIG. 6 is a graph illustrating the temperature in the auxiliary cooling circuit 5 of the thermoacoustic system 20, as a function of the speed of the motor vehicle, according to the second embodiment of FIG. 5.

The graph of FIG. 6 illustrates the evolution of the temperature at three points in the cooling circuit 32, identified in FIG. 5 by the references A, B and C.

The point A is the coldest location in the cooling circuit 32 annex, and is between the pump 34 annex and the exchanger 28 cold first module 24. The temperature TA at this point A is not adversely affected by the cold exchanger 28 of the first module 24. Since the speed of movement of the automobile vehicle 1 has no appreciable effect on this temperature TA, the evolution curve of the temperature at point A in FIG. .

The point B is located between the cold exchanger 28 of the first module 24 and the cold exchanger 28 of the second module 25. The temperature TB at point B is greater than the temperature TA at point A, a heat exchange having The coolant has warmed up as it passes through the cold exchanger 28 of the first module 24. The higher the vehicle's vehicle speed, the higher the temperature at point B.

The point C is located after the cold exchanger 28 of the second module 25. The temperature Tc at point C is greater than the temperature TA, T b at points A and B, because two heat exchanges have taken place, the coolant having warmed as it passes through the cold exchanger 28 of the first module 24 and further warmed as it passes through the cold exchanger 28 of the second module 25. The higher the vehicle 1 vehicle will have a higher speed of movement, the more the temperature Tc at point C will be high.

The third embodiment, shown in FIG. 7, is identical to the second embodiment shown in FIG. 5, with one exception: in the third embodiment, illustrated in FIG. 7, the auxiliary cooling circuit 32 is divided into two parts. flux. The first flow goes towards the cold exchanger 28 of the first module 24, while the second flow goes towards the cold exchanger 28 of the second module 25.

This architecture ensures a lower temperature to the liquid flowing in the auxiliary cooling circuit 32 that the temperature of the liquid flowing to the cold exchanger 28 of the second module 25 according to the previous embodiments.

Thus, the efficiency of the thermoacoustic system 20 is improved.

According to a fourth embodiment, illustrated in FIG. 8, the radiator 15 is used as a cold source for the auxiliary cooling circuit 32, the attached pump 34 being connected to the radiator 15 outlet by means of a coupling 19. while the auxiliary cooling circuit 5 opens at the inlet of the radiator 15 by means of a hydraulic coupling 19. This embodiment incorporates an auxiliary heat exchanger 33, arranged in parallel with the radiator 15, the inlet and the outlet of this auxiliary heat exchanger 33 being managed by solenoid valves 18.

According to a fifth embodiment, illustrated in FIG. 9, the architecture of the fourth embodiment is repeated by adding solenoid valves 18 to the inlet and the outlet of the cabin heater unit 12, as well as at the outlet of the cooling circuit 5. This embodiment incorporates an auxiliary heat exchanger 33 between the pump 34 annex and the radiator 15, for the purpose of further cooling the cooling liquid, in the case of life where the radiator 15 is still hot.

According to a sixth embodiment, illustrated in Figure 10, we take the architecture of the fifth embodiment by adding heat exchanger 33 annex in parallel with the radiator 15, the inlet and the outlet of this exchanger 33 of auxiliary heat being managed by solenoid valves 18.

According to a seventh embodiment, illustrated in FIG. 11, the architecture of the fourth embodiment is repeated, by adding solenoid valves 18 at the end of the auxiliary cooling circuit 32 and at the input of the circuit 5 of FIG. cooling, so as to recover the thermal energy at the exhaust of the engine 2. Another solenoid valve 18 is disposed at the outlet of the cabin heater unit 12, in order to carry the cooling liquid back into the circuit 32 of additional cooling, between the cold exchanger 28 of the first module 24 and the cold exchanger 28 of the second module 25. This embodiment incorporates a heat exchanger 33 annex between the annex pump 34 and the radiator 15, for the purpose of cooling still more the coolant, in the case of life where the radiator 15 would still be hot.

According to an eighth embodiment, illustrated in FIG. 12, the architecture of the seventh embodiment is taken up, by adding an auxiliary heat exchanger 33 between the annex pump 34 and the radiator 15, for the purpose of cooling. still more the coolant, in the case of life where the radiator 15 would still be hot.

According to a ninth embodiment, illustrated in FIG. 13, the architectures of the seventh embodiment and of the eighth embodiment are combined and an additional heat exchanger 33 is added between the attached pump 34 and the radiator 15, in the purpose of further cooling the coolant, in the case of life where the radiator 15 would still be hot.

According to a tenth embodiment, illustrated in FIG. 14, the architectures of the seventh embodiment and the tenth embodiment are combined, and an additional heat exchanger 33 is added between the attached pump 34 and the radiator 15. for the purpose of further cooling the coolant, in the case of life where the radiator 15 would still be hot.

[0077] Engine 2 comprising a thermoacoustic system 20 as described above has many advantages. In particular, the engine makes it possible to: - recover the thermal energy at the exhaust of the engine 2, to reuse it, - reduce fuel consumption, - reduce the emissions of gaseous pollutants, - manage the influx of hot air in the passenger compartment 13, convert the thermal energy of the engine 2 into electrical or mechanical energy, via the thermoacoustic system.

Claims (9)

A combustion engine (2) having a cylinder block (3) having a plurality of cylinders (4), an exhaust manifold (31), a cooling circuit (5), wherein circulates a cooling liquid, a radiator (15), and a thermoacoustic system (20) comprising: a resonator (21) comprising a pressurized gas, an emitter (29) of acoustic waves, capable of producing a acoustic wave inside the resonator (21), at least two thermoacoustic modules (24, 25), arranged inside the resonator (21), the two modules (24, 25) being respectively composed of a structure ( 26), bordered by a heat exchanger (27) and a cold exchanger (28), and allowing the acoustic wave to pass through and to amplify its acoustic energy, an energy converter (30) capable of converting the acoustic wave acoustic energy of an acoustic wave in electrical energy, characterized in that the heat exchanger (27) of the first module (24) thermoacoustic is connected to a circuit (8) radiator, extending the cooling circuit (5) through a water outlet housing (6) and joining the radiator (15), the heat exchanger (27) of the second module (25) being connected to the exhaust manifold (31). 2. Engine (2) according to claim 1, characterized in that it comprises a heating circuit (7) extending the cooling circuit (5) cooling through the housing (6) of water outlet, comprising a nozzle ( 11) and a cabin heater unit (12). 3. Motor (2) according to any one of the preceding claims, characterized in that it comprises a recirculation circuit (9) extending the cooling circuit (5) through the housing (6) water outlet. 4. Motor (2) according to any one of the preceding claims, characterized in that the circuit (8) radiator comprises a first bifurcation (17) implemented by means of a solenoid valve (18) and a coupling ( 19), able to avoid the use of the radiator (15). 5. Motor (2) according to the preceding claim, characterized in that the circuit (8) radiator comprises a second bifurcation (35) implemented by means of two solenoid valves (18), adapted to conduct the cooling liquid directly to the first bifurcation (17), without passing through the heat exchanger (27) of the first hot module (24). 6. Engine (2) according to any one of claims 2 to 5, characterized in that the heat exchangers (28) of the thermoacoustic modules (24, 25) are connected to an auxiliary cooling circuit (32), in which a coolant circulates, comprising a pump (34) attached. 7. Motor (2) according to claim 6, characterized in that a heat exchanger (33) of annex heat is disposed between the output of the radiator (15) and the pump (34) annex. 8. Motor (2) according to claim 6, characterized in that the circuit (32) of auxiliary cooling is separated into two streams, by means of a connection (19) arranged between the hydraulic exchanger (28) cold first module (24) and the cold exchanger (28) of the second module (25). 10. Motor (2) according to claim 7, characterized in that a heat exchanger (33) of heat is arranged parallel to the radiator (15) by means of two solenoid valves (18).