FR3055668A1 - MOTOR ASSEMBLY FOR MOTOR VEHICLE COMPRISING A THERMAL ENERGY RECOVERY DEVICE - Google Patents

Abstract

The invention relates to a motor assembly for a motor vehicle comprising a burner (3) of solid particles to be burned in a combustion chamber with a fixed volume, the combustion chamber being connected to a line (6) for exhausting the combustion gases and a system (5) for recovering solid residues resulting from the combustion of the particles, characterized in that it comprises a device for recovering thermal energy released by combustion and for converting this recovered energy into electrical and / or mechanical energy .

Description

Holder (s): PEUGEOT CITROEN AUTOMOBILES SA Société anonyme.

Extension request (s)

Agent (s): PEUGEOT CITROEN AUTOMOBILES SA Public limited company.

MOTOR ASSEMBLY FOR A MOTOR VEHICLE COMPRISING A THERMAL ENERGY RECOVERY DEVICE.

FR 3 055 668 - A1 (5 / y The invention relates to an engine assembly for a motor vehicle comprising a burner (3) of solid particles to be burned in a combustion chamber with fixed volume, the combustion chamber being connected to a line ( 6) exhaust of combustion gases and a system (5) for recovering solid residues resulting from the combustion of particles, characterized in that it comprises a device for recovering thermal energy released by combustion and for converting this energy recovered into electrical and / or mechanical energy.

MOTOR VEHICLE ASSEMBLY COMPRISING A THERMAL ENERGY RECOVERY DEVICE

The present invention relates to machines operating with solid combustion as a hot source.

Most current internal combustion engines use a liquid fuel comprising carbon, the combustion of which therefore emits CO ₂ .

The combustion of solid particles in an engine is also known, for example, from document US8100095B2, a piston engine using the combustion of solid particles in a combustion chamber to move the piston and thus recover mechanical energy.

The combustion of metal particles, as detailed in the article "Direct combustion of recyclable metal fuels for zero-carbon heat and power" of the journal Applied Energy, 2015 is a solution mentioned to produce combustion without emission of CO ₂ , for motor vehicles.

However, the adiabatic combustion temperature (of the oxidation reaction) of solid particles can be higher (> 2500 ° C) than that of conventional fuels (petrol, diesel, natural gas: ~ 2000 ° C), which implies radiation more important towards the walls and consequently a significant loss of energy towards the walls, which is lost by heat transfers.

To achieve this objective, there is provided according to the invention an engine assembly for a motor vehicle comprising a solid particle burner to be burned in a combustion chamber with fixed volume, the combustion chamber being connected to an exhaust line for the exhaust gases. combustion and a system for recovering solid residues resulting from the combustion of particles, characterized in that it comprises a device for recovering thermal energy released by combustion and for converting this recovered energy into electrical and / or mechanical energy.

In a variant, the device for recovering thermal energy comprises a thermo-acoustic converter connected, for its hot source, to a heat exchanger disposed on the exhaust line and / or on the system for recovering solid residues and / or on the burner.

Advantageously, the thermal energy recovery device is a Rankine loop device.

Advantageously also, the Rankine loop thermal energy recovery device is connected, for its hot source, to a heat exchanger disposed on the exhaust line and / or on the solid residue recovery system and / or on the burner (3).

In another variant, the thermal energy recovery device is a Brayton cycle device.

Advantageously, the Brayton cycle thermal energy recovery device is connected, for its hot source, to a heat exchanger disposed on the exhaust line and / or on the solid residue recovery system and / or on the burner.

Advantageously again, the engine assembly comprises two compression stages and an intermediate cooler between the two compression stages.

In another variant, the thermal energy recovery device is a Stirling machine comprising a hot head connected to a heat exchanger disposed on the exhaust line and / or to the solid residue recovery system and / or to the burner.

Advantageously, the Stirling machine comprises an external regenerator for heating the air admitted into the burner, this external regenerator being thermally connected to the heat exchanger disposed on the exhaust line.

Advantageously also, the Stirling machine comprises a multi-stage hot head, each stage being independently connected to one of the hot sources that are the heat exchanger disposed on the exhaust line, the solid residue recovery system, the burner.

Other particularities and advantages will appear on reading the description below of a particular embodiment, without limitation of the invention, made with reference to the figures in which:

- Figure 1 is a schematic representation of a first embodiment of the invention.

- Figure 2 is a schematic representation of a variant of the first embodiment.

- Figure 3 is a schematic representation of another embodiment of the invention.

- Figure 4 is a schematic representation of a variant of the embodiment illustrated in Figure 3.

- Figure 5 is a schematic representation of another variant of the embodiment illustrated in Figure 3.

- Figure 6 is a schematic representation of another embodiment.

- Figure 7 is a schematic representation of a variant of the embodiment illustrated in Figure 6.

- Figure 8 is a schematic representation of another variant of the embodiment illustrated in Figure 6.

- Figure 9 is a schematic representation of another embodiment.

- Figure 10 is a schematic representation of a variant of the embodiment illustrated in Figure 9.

- Figure 11 is a schematic representation of another variant of the embodiment illustrated in Figure 9.

FIG. 1 shows a first embodiment of the engine assembly according to the invention. Such an assembly is based on the combustion of solid particles not containing carbon. Consequently, this combustion reaction does not produce CO ₂ . Such an assembly may be suitable for the motorization of vehicles to allow their movement, whose authorized CO ₂ emissions are more and more restricted.

The air 1 and the solid particles 2 are premixed and then burn in the combustion chamber of a burner 3. Unlike a combustion carried out in the combustion chamber of an internal combustion engine whose volume varies depending on the cycle, the burner 3 has a combustion chamber with fixed volume.

The amount of air in the burner and therefore the power of the engine assembly can be increased by the use of an air compressor 4. This compressor 4 also has the function of overcoming the pressure drops in the various components.

An external energy supply initiates the oxidation reaction of the solid fuel. This oxidation reaction is an exothermic reaction and therefore releases energy in the form of heat. Several parameters make it possible to control the power of the burner: The air flow, the flow of solid particles, the thermodynamic conditions in the combustion chamber (pressure, temperature), the geometry of the burner and of the combustion chamber. At the outlet of the combustion chamber, the mixture passes through a system 5 for recovering the solid residues resulting from the combustion of the particles which allows the separation of the oxidation products in the form of solid particles and the gaseous part (hot air and other products oxidation in gaseous form) and the collection in a tank of solid residues while the hot gases continue their way in an exhaust line 6.

In this first embodiment, the thermal energy released by the combustion of solid particles is recovered by a thermo-acoustic converter 7 to be converted into electrical or mechanical energy.

The principle of the thermal-acoustic converter is as follows: a pressurized gas confined in a tube 8 is excited, so an acoustic power is applied to the input We. The gas particles pass through a porous structure 9 heated on one side 10 and cooled on the other side 11 and also designated "stack" in English or also regenerative. The gas particle then describes a thermodynamic cycle and the acoustic wave applied to the input will be amplified (Wac> We) by the effect of temperature. This amplified wave will in turn be transformed into electricity or mechanical energy by an appropriate converter 12. The transformation into mechanical energy can be carried out by a bidirectional turbine. The transformation into electrical energy can be achieved by an electroacoustic device.

The hot springs are here the places through which the engine assembly loses energy: the burner 3 with losses at the walls, the device 5 for recovery due to the high temperature of the oxidized particles and the exhaust line 6 crossed by hot combustion gases.

In this embodiment, in order to carry out the heat transfer from the exhaust gases to the hot side 10 of the structure 9 of the thermoacoustic converter 7, the engine assembly comprises a first heat exchange loop 13 inside which circulates a heat transfer fluid. A pump can be provided to assist the circulation of the fluid inside this heat exchange loop 13.

In order to carry out the heat dissipation from the cold side 11 of the structure 9 of the thermo-acoustic converter 7, the motor assembly comprises a second heat exchange loop 14 inside which circulates a heat transfer fluid. A pump can also be provided to assist the circulation of the fluid inside this heat exchange loop 14.

A first heat exchanger 15 is disposed in the heat exchange loop 13, in thermal contact with the exhaust line 6 as a hot source so as to capture the calories conveyed by the exhaust gases to transfer them to the heat transfer fluid. This first heat exchanger 15 intended to transfer heat from the exhaust line to the heat transfer fluid. This heat exchange loop 13 can be in the form of a heat pipe.

A second heat exchanger 16 is disposed in the heat exchange loop 13, in thermal contact with the hot side 3 of the porous structure 9 of the thermal-acoustic converter so as to restore the calories conveyed by the heat transfer fluid to the hot side 3. It is used to heat the excited gas, to amplify the acoustic wave.

A third heat exchanger 17 is arranged in the second heat exchange loop 14, in thermal contact with the cold side 4 to be cooled so as to capture the calories not transformed into useful work to transfer them to the heat transfer fluid.

A fourth heat exchanger 18 is disposed in the second heat exchange loop 14, in thermal contact with a circulation of coolant or ambient air as a cold source so as to evacuate the calories conveyed by the heat transfer fluid by this cold source .

In order to improve the recovery of energy from the hot gases passing through the exhaust line 6, at least one other module 9a can be provided, the hot side 10a of which is connected by a heat exchange loop 13a to the line 6 of exhaust. The heat exchanger capturing the calories conveyed by the exhaust gases to transfer them to the heat transfer fluid may be common to the first heat exchanger 15. The cold side 11a is connected by a heat exchange loop 14a to the cold source. The heat exchanger evacuating the calories conveyed by the heat transfer fluid by this cold source may be common to the fourth heat exchanger 18.

In order to further improve energy recovery, at least one other module 9b can be provided, the hot side 10b of which is connected by a heat exchange loop 13b to the system 5 for recovering solid residues. The cold side 11b is connected by a heat exchange loop 14b to the cold source. The heat exchanger evacuating the calories conveyed by the heat transfer fluid by this cold source may be common to the fourth heat exchanger 18.

In order to further improve energy recovery, at least one other module 9c can be provided, the hot side 10c of which is connected by a heat exchange loop 13c to the burner 5. The cold side 11c is connected by a loop of heat exchange 14c at the cold source. The heat exchanger evacuating the calories conveyed by the heat transfer fluid by this cold source may be common to the fourth heat exchanger 18.

FIG. 2 shows a variant of the previous embodiment in which the two structures 9b and 9c are replaced by a single structure 9d whose hot side 10d is connected by a heat exchange loop 13d passing in series through the burner 3 and the solid residue recovery system 5. This more economical variant makes it possible to recover both the energy of the radiation on the walls of the combustion chamber of the burner but also the energy of solid residues. The cold side 11d is connected by a heat exchange loop 14d to the cold source. The heat exchanger evacuating the calories conveyed by the heat transfer fluid by this cold source may be common to the fourth heat exchanger 18.

FIG. 3 shows another embodiment of the engine assembly according to the invention. In this new embodiment, the thermal energy released by the combustion of solid particles is recovered this time by a Rankine thermodynamic loop device.

In this embodiment, the Rankine loop energy recovery device comprises a heat exchange loop 20 inside which a working fluid circulates. A heat exchanger 15, also called an evaporator, is disposed in the heat exchange loop 20, in thermal contact with the exhaust line 6 as a hot source so as to capture the calories conveyed by the hot gases to transfer them to the fluid of job.

From the heat exchanger 5, in a direction of flow of the fluid 7 inside the heat exchange loop 20, the energy recovery device further comprises an expansion member 21 capable of transforming the energy from the expansion of the fluid in mechanical torque to the wheels of the vehicle or to drive a generator to produce electricity, a condenser 22 inside which the fluid condenses and a pump 23 to circulate the fluid inside the heat exchange loop 20.

In order to further improve energy recovery, one can provide another heat exchange loop 20 ′, independent of the previous heat exchange loop 20, and the hot source of which is the system 5 for recovering solid residues. The 20 ’heat exchange loop includes its own expansion 21’, condenser 22 ’and pump 23’.

In order to further improve energy recovery, we can provide another heat exchange loop 20 ”, independent of the previous heat exchange loops 20, 20 'and whose hot source is the burner 3. The heat loop 20 ”heat exchange includes its own 21” expansion valve, 22 ”condenser and 23” pump. The working fluids in the different Rankine loops are not necessarily the same. The working fluids can be adapted to the temperature level in the different branches in order to improve the yield.

FIG. 4 presents a variant of the previous embodiment in which the two heat exchange loops 20 ′, 20 ”are replaced by a single heat exchange loop 20a whose hot source is a passage in series by the burner 3 and the solid residue recovery system 5. This heat exchange loop 20a includes its own expansion member 21a, condenser 22a and pump 23a.

FIG. 5 presents another variant of the embodiment presented in FIG. 3 in which the three exchange loops 20, 20 ′, 20 ”are replaced by a single heat exchange loop 20b, the hot source of which consists of a passage in series through the burner, the system 5 for recovering solid residues and the heat exchanger 15, in thermal contact with the exhaust line 6. This heat exchange loop 20b includes its own expansion member 21b, condenser 22b and pump 23b.

FIG. 6 shows another embodiment of the engine assembly according to the invention. In this new embodiment, the thermal energy released by the combustion of solid particles is recovered this time by a Brayton thermodynamic loop device.

The Brayton cycle is a technology that uses a working gas gas (e.g. air if the loop is open, i.e. without condenser) to produce energy. The cycle consists of a compressor which compresses the gas, thus increasing its temperature and pressure. The compressed gas passes through a heat exchanger which exchanges with a hot source and undergoes heat addition at constant pressure, which will increase its pressure and its temperature, therefore its enthalpy. The gas then passes through a work-producing turbine. Part of the recovered mechanical work will be used to drive the compressor, the rest will be used to drive an electric generator to generate electricity.

In this embodiment, the Brayton cycle energy recovery device comprises a heat exchange loop 30 inside which the working gas circulates. The Brayton loop is here open, without condenser. The energy recovery device comprises a compressor 33 which compresses the gas. The air at the outlet of the compressor 33 exchanges, with the first hot source, the system 5 for recovering solid residues, then with the second hot source, the burner 3 and finally as the third hot source with the heat exchanger 15 of the line. 6 exhaust. At the outlet of the heat exchanger 15, the heated air expands in the turbine 31 by producing work, therefore a mechanical torque which will be returned to the tires where well an electric generator is driven. The rest of the energy which could not be transformed into useful work will be evacuated outside at the outlet of turbine 31.

FIG. 7 presents a variant of the previous embodiment. This variant differs from the previous embodiment in that the Brayton cycle energy recovery device comprises two compression stages with a second compressor 33a, and an intermediate cooler 34. The advantage of using two stages of compression with intermediate cooling is to better recover the energy available, which makes it possible to optimize the overall efficiency and reduce the compression work, thus improving the total net work.

FIG. 8 presents another variant of the embodiment presented in FIG. 6 in which the heat exchange loop 30a has two compression stages with a second compressor 33a, and an intermediate cooler 34 and the energy is recovered first. at the level of the burner 3, then the energy at the level of the system 5 for recovering solid residues, then at the level of the heat exchanger 15 of the exhaust line 6. The choice of the order of passage of the hot springs depends on their temperature levels.

FIG. 9 shows another embodiment of the engine assembly according to the invention. In this new embodiment, the thermal energy released by the combustion of solid particles is recovered this time by a Stirling 40 machine.

In this embodiment, the Stirling 40 machine comprises a hot head connected, as a hot source, to the heat exchanger 15 of the exhaust line 6. It could also be connected to a hot source, alone or in combination with the burner 3 and / or the system 5 for recovering solid residues.

FIG. 10 presents a variant of the previous embodiment. This variant differs from the previous embodiment in that the hot head 42 of the Stirling machine 40 is connected, for its hot source, to the heat exchanger 15 of the exhaust line 6, to the burner 3 and to the system 5 solid residue recovery. This variant still differs from the previous embodiment in that the Stirling machine 40 comprises an external regenerator 41 connected to the exchanger 15 to heat the air intended to enter the burner 3, which makes it possible to reduce the supply of heat. in my combustion chamber and therefore the solid fuel consumption. In this variant the regenerator 41 is upstream of the intake air compressor 4, but in a variant not shown, this regenerator 41 could be connected to the exchanger 15, while being disposed between the compressor 4 and the inlet of the burner 3.

FIG. 11 shows another variant of the embodiment presented in FIG. 9. In this variant, the hot head of the Stirling machine 40 comprises several stages, here three, 42a, 42b and 42c, each one being independently connected to one of the three hot springs constituted by the burner 3, the system 5 for recovering solid residues, the heat exchanger 5 of the exhaust line 6. Having a multi-stage hot head makes it possible to bring heat at several different temperature levels to the Stirling 40 machine, which avoids mixing the three sources upstream and losing work potential.

The invention is not limited to the examples described. As a variant, other combinations 5 connecting the heat recovery device to the hot sources that are the burner 3, the energy recovery system 5 and the heat exchanger 15 can be envisaged.

This invention maximizes the overall efficiency of a thermodynamic converter 10 operating with solid particles.

Claims (10)

Claims 1. Engine assembly for a motor vehicle comprising a burner (3) of solid particles to be burned in a combustion chamber with fixed volume, the combustion chamber being connected to a line (6) for exhausting the combustion gases and a system ( 5) for recovering solid residues from the combustion of particles, characterized in that it comprises a device (7) for recovering thermal energy released by combustion and for converting this recovered energy into electrical and / or mechanical energy . 2. Motor assembly according to claim 1, characterized in that the thermal energy recovery device comprises a thermo-acoustic converter (7) connected, for its hot source, to a heat exchanger (15) arranged on the line ( 6) exhaust and / or on the system (5) for recovering solid residues and / or on the burner (3). 3. Motor assembly according to claim 1, characterized in that the thermal energy recovery device is a Rankine loop device (20, 20 ’, 20”). 4. Motor assembly according to claim 3, characterized in that the Rankine loop thermal energy recovery device is connected, for its hot source, to a heat exchanger (15) disposed on the line (6) of exhaust and / or on the solid residue recovery system (5) and / or on the burner (3). 5. Motor assembly according to claim 1, characterized in that the thermal energy recovery device is a Brayton cycle device (30). 6. Motor assembly according to claim 5, characterized in that the Brayton cycle thermal energy recovery device (30) is connected, for its hot source, to a heat exchanger (15) disposed on the line (6 ) exhaust and / or on the solid residue recovery system (5) and / or on the burner (3). 7. Motor assembly according to claim 5 or claim 6, characterized in that it comprises two compression stages (33, 33a) and a cooler (34) intermediate between the two compression stages (33, 33a). 8. An engine assembly according to claim 1, characterized in that the thermal energy recovery device is a Stirling machine (40) comprising a hot head (42) connected to a heat exchanger (15) disposed on the line ( 6) exhaust and / or to the system (5) for recovering solid residues and / or to the burner (3). 9. Engine assembly according to claim 8, characterized in that the Stirling machine (40) comprises an external regenerator (41) for heating the air admitted into the burner, this 5 external regenerator (41) being thermally connected to the heat exchanger (15) arranged on the exhaust line (6). 10. Engine assembly according to claim 8 or claim 9, characterized in that the Stirling machine (40) comprises a hot head with several stages, each stage (42a, 42b, 42c) being independently connected to one of the hot sources that are 10 the heat exchanger (15) disposed on the exhaust line (6), the system (5) for recovering solid residues, the burner (3). 1/5