FR2884555A1 - Vehicle IC engine energy recuperator has nitrogen oxide trap in exhaust line and Rankine cycle system with loop containing compressor and evaporator - Google Patents

Abstract

An energy recuperator, using a system with a Rankine thermodynamic cycle coupled to a vehicle IC engine exhaust pipe, comprises a nitrogen oxide (NOx) trap (3) in the exhaust line and a loop (4) in the Rankine cycle system with a compressor (13) and evaporators (5, 7) located before and/or after the NOx trap that can be connected thermally with the exhaust gases. It also has an energy expander/recuperator (6) and a regulator to control the heat exchange between the evaporators and the exhaust gases. It also has a selector (9) to regulate the amount of exhaust gases fed through the loop.

Description

of Rankine comprising a fluid loop comprising means for

  compression, evaporator means located upstream and / or at the NOx trap and capable of being thermally coupled with the exhaust gas, means of

  relaxation / energy recovery and in that it comprises control means adapted to control the heat exchange between the evaporator means and the exhaust gas.

  Furthermore, the invention may comprise one or more of the following features: the exhaust line comprises selective means for diverting at least a portion of the exhaust gases, able to regulate the amount of exhaust gas; exhaust in heat exchange with the Rankine cycle fluid loop, the device comprises means for regulating the fluid flow of the loop intended to flow in the evaporator means, the loop comprises evaporator means located downstream of the trap. Nox, the exhaust line comprises one or more additional depollution means chosen from the following means: catalytic means, precatalysis means, particle filter means, the loop comprises first and second evaporator means located upstream of additional depollution means, the first and second evaporator means are integrated in a single heat exchanger, the first and second The exhaust pipe comprises pre-catalytic means arranged upstream of the Nox trap on the one hand and evaporator means on the other; the device comprises catalytic means integrated in evaporator means; evaporators comprise a heat exchanger capable of thermally coupling the fluid of the loop and the exhaust gas, and in that the catalytic means are disposed on surfaces of the evaporator means able on the one hand to be in contact with the flow of the exhaust gas and secondly, to be coupled thermally directly or indirectly with the fluid of the loop, the device comprises Nox trap means integrated in evaporator means, - the evaporator means comprise a heat exchanger capable of coupling thermally the fluid of the loop and the exhaust gas, and in that the NOx trap means are disposed on surfaces of the evaporator means ap on the one hand to be in contact with the flow of the exhaust gas and on the other hand, to be thermally coupled directly or indirectly with the fluid of the loop.

  Other particularities and advantages will appear on reading the following description, made with reference to the figures in which: FIG. 1 represents a schematic view of a first exemplary embodiment of the energy recovery device of FIG. an internal combustion engine according to the invention, - Figures 2, 3, 5 and 6 show schematic and simplified views of four other embodiments of the device according to the invention, - Figure 4 shows a schematic view and section of a detail of Figures 3, 5 and 6, illustrating the structure of an evaporator exchanger providing a Nox trap function and / or catalysis according to the invention.

  The invention will now be described with reference to the embodiment of FIG. 1. An exhaust line 2 comprising a depollution member 3 is connected to the thermal engine 1. The pollution control member 3, 33 comprises a Nox trap 3 and, optionally, one or more additional pollution control members 33, 133 such as a catalyst or a particle filter or any other equivalent means or combination of these means.

  A Rankine thermodynamic cycle fluid loop 4 is thermally coupled to the exhaust line 2. The fluid of the loop 4 is for example water. In what follows, thermal transfer or heat exchange is any transfer of calories or frigories between two elements, either directly or indirectly via a vector such as a fluid.

  The loop 4 conventionally comprises a pump 13 for compressing the water. The water heats up and then vaporizes in a preheater 5 during a heat exchange with the exhaust gas. The preheater 5 consists, for example, of a first heat exchanger water / exhaust gas. The water is also heated and vaporized in a second exchanger 7 water / exhaust gas also called recuperator or superheater. In these two exchangers 5, 7, the exhaust gases give calories to the water. The steam obtained then undergoes expansion in a turbine 6 thus providing a recoverable work on a rotating shaft 16. This energy can be used directly to mechanically drive an organ, or be converted into electricity in an electric converter 26.

  The water vapor is then returned to its initial liquid state in a condenser 8 which cools it. The condenser 8 may consist of a heat exchanger capable of thermally coupling the water of the loop 4 with air or any other cooling fluid. The thermal power to be dissipated in the condenser 8 may if necessary be used to heat a passenger compartment or an organ for example.

  The preheater 5 and the recuperator 7 are respectively disposed downstream and upstream of the depollution member 3, the upstream and downstream qualifiers referring to the direction of flow of the exhaust gases.

  Advantageously, regulation means 9 are provided to control the heat exchange between on the one hand the preheater 5 and recuperator 7 and on the other hand the exhaust gas.

  For example, the exhaust line 2 comprises two separate ducts and a valve 9 for distributing the flow of exhaust gas between the two ducts 2. Preferably, the two ducts 2 pass through the body 3 depollution. One of the two ducts 2 is in heat exchange with the preheater 5 and recuperator exchangers 7, while the other duct 2 is not in heat exchange with the latter. Thus, the control of the valve 9 makes it possible to determine the quantity of exhaust gas thermally coupled to the Rankine loop 4.

  The regulation means 9, 2 thus make it possible to control the temperature of the exhaust gases entering the Nox trap 3 without greatly affecting the thermodynamic efficiency of the Rankine loop 4. The superheater 7 of the Rankine cycle is thus used as a NOx trap cooler 3.

  This architecture has the additional advantage of not requiring a specific calibration of the engine control to maintain the exhaust gas temperature below a threshold temperature (800 C for example). Indeed, for a particular gasoline engine, it may be common to reach temperatures above this threshold, especially on high load operating points. Such a calibration according to the prior art is penalizing in terms of efficiency and consumption (overconsumption) of the engine.

  Furthermore, in the case where the 3 depollution member comprises a catalyst 33, the control means 9, 2 can not compromise the priming of the catalyst when its temperature is relatively low. The gas bypass system makes it possible to bypass the superheater 7 in particular so as not to degrade the rise in temperature of the catalyst 133.

  This architecture also makes it possible to install a superheater 7 as close as possible to the exhaust manifold 10 of the engine 1. This makes it possible to provide a superheater / exhaust heat exchange at a location where the gas temperatures are very high. high yielding the Rankine cycle.

  In addition, the regulation means 9, 2 make it possible to divert all or part of the exhaust gases when the engine 1 is operating at full load and the thermal power of the exhaust gases is too great compared to the dimensioning of the rest of the system .

  The position of the superheater 7 upstream of the trap 3 to Nox is particularly advantageous. Indeed, the superheater 7 can provide selective cooling of the exhaust gas before entering the trap 3 to NOx when they present a temperature is too high. In this way, the invention makes it possible to guarantee compliance with the operating temperature and efficiency window of the NOx trap 3, in particular when the engine 1 is of the direct injection gasoline type.

  Thus, the device according to the invention has a high compactness, a high efficiency while having a relatively simple structure that adapts to the operating constraints of the exhaust lines having complex depollution organs.

  In a variant, the means for regulating the heat exchange between the evaporator means 5 and 7 and the exhaust gases may comprise (or consist only of) means for varying the flow rate of the fluid of the loop 4 allowed to circulate in the Evaporators 5, 7. For example, the pump 13 of the loop 4 or a valve can provide this regulation depending in particular on the temperature of the exhaust gas.

  Figures 2 to 6 illustrate other embodiments of the invention. For the sake of simplicity and brevity, in these figures, elements identical to those described above are designated by the same reference numerals and are not described in detail a second time. In addition, the Rankine cycle loop 4 is shown partially and schematically. That is, only the heat exchangers thermally coupled to the exhaust gas (evaporator 5 and / or preheater 7) are shown.

  The embodiment of FIG. 2 differs from that of FIG. 1 only in that the exhaust line 2 comprises a single duct which is thermally coupled with the evaporator 5 and the superheater 7.

  The regulation of the heat exchange between the means 5, 7 evaporators and the exhaust gas can be achieved by controlling the fluid flow rate of the loop 4 admitted to circulate in the evaporators 5, 7 (by means for example of the pump 13 and / or a valve not shown).

  In the embodiment of FIG. 3, the loop 4 comprises a single heat exchanger 5, 7 providing the functions of evaporator 5 and superheater 7. The heat exchanger 5, 7 is disposed downstream of an element 11 optional precatalysis and upstream of a depollution module 3 comprising a particle filter 33 and a Nox trap 3. Furthermore, the Rankine cycle loop 4 comprises means 12 for regulating the flow of fluid intended to come into thermal exchange with the exhaust gases in the exchanger 5, 7.

  For example, a controlled valve 12 makes it possible to control the flow of water flowing in the evaporator / superheater 5, 7.

  Furthermore, and preferably, the exchanger 5, 7 evaporator / superheater also performs a function of catalysis. For example, and as shown in Figure 4, conventional catalyst means 133 are disposed on one of the surfaces of the exchanger 5, 7 adapted to be in contact with the flow of exhaust gas. For example, catalytic compounds 133 are deposited on fin surfaces 34 of the exchanger 5, 7. The fins 34 are thermally coupled directly or indirectly with the fluid of the loop 4 which circulates in the exchanger 5, 7. For example, the fluid of the Rankine loop circulates in passages 35 contiguous to the fins 34.

  This architecture, which has a high efficiency in terms of heat exchange and catalysis, has a particularly small footprint.

  The embodiment of FIG. 5 differs from that of FIGS. 3 and 4 only in that the evaporation and superheating functions 7 are provided by two distinct heat exchangers 5, 7 disposed respectively downstream and upstream of the pollution control module comprising the Nox trap 3 and the particle filter 33. The superheater 7 is in turn placed downstream means 11 of precatalysis.

  As previously, a controlled valve 12 can be provided to control the flow of water of the loop 4 which circulates in the evaporator 5 and / or the superheater 7. As previously, the exchanger constituting the superheater 7 can also integrate in its within the means 133 of catalysis.

  The embodiment of FIG. 6 differs from that of FIGS. 3 and 4 only in that the depollution module 3 comprises only a particle filter 33, the means 3 forming a Nox trap also being integrated in the exchanger 5, 7 evaporator / superheater. Indeed, in the same way as for the catalytic means, the means 3 forming Nox trap can be integrated within the exchanger 5, 7.

  In this embodiment, preferably, the means 133 of catalysis are arranged in the exchanger 7 upstream of the means 3 forming a Nox trap. That is, the burned exhaust gases entering the exchanger 5, 7 are first in contact with the catalytic means 133 before being in contact with the Nox trap 3.

  Moreover, in another embodiment that can be envisaged, only the means 3 forming a Nox trap are integrated within the exchanger 5, 7. That is, the catalytic means 133 can be located in a separate body from that providing both heat exchange and Nox trap 3.

Claims (13)

  1. A device for recovering energy from an internal combustion engine by means of a Rankine thermodynamic cycle system coupled to the exhaust line (2) of the engine (1), characterized in that the line of exhaust (2) comprises a Nox trap (3), the Rankine cycle system comprising a fluid loop (4) comprising compression means (13), evaporator means (5, 7) located upstream and / or at the level of the trap (3) lo lox and capable of being coupled thermally with the exhaust gas, means (6) of relaxation / energy recovery and that it comprises means (12, 9) of control capable of controlling the heat exchange between the evaporator means (5, 7) and the exhaust gases.   2. Device according to claim 1, characterized in that the line (2) of the exhaust comprises means (9) selective bypass of at least a portion of the exhaust gas, able to regulate the amount of gas. exhaust in heat exchange with the loop (4) of Rankine cycle fluid.   3. Device according to claim 1 or 2, characterized in that it comprises means (12, 13) for regulating the fluid flow rate of the loop (4) for circulating in the means (5, 7) evaporators.   4. Device according to any one of the preceding claims, characterized in that the loop (4) comprises means (5) evaporators located downstream of the trap (3) Nox.   5. Device according to any one of the preceding claims, characterized in that the exhaust line comprises one or more means (33, 133) of additional pollution control selected from the following means: catalytic means, precatalysis means, particle filter means. he   6. Device according to claim 5, characterized in that the loop (4) comprises first (5) and second (7) means (5) evaporators located upstream means (33, 133) of additional pollution.   7. Device according to claim 6, characterized in that the first (5) and second (7) evaporator means are integrated in a single heat exchanger.   8. Device according to any one of the preceding claims, characterized in that the exhaust line (2) comprises pre-catalysis means (11) arranged upstream on the one hand of the Nox trap (3) and, on the other hand means (5, 7) evaporators.   9. Device according to any one of the preceding claims, characterized in that it comprises means (133) of catalysis integrated in means (5, 7) evaporators.   10. Device according to claim 9, characterized in that the means (5, 7) evaporators comprise a heat exchanger capable of thermally coupling the fluid of the loop (4) and the exhaust gas, and in that the means (33) ) of catalysis are arranged on surfaces evaporator means (5, 7) able on the one hand to be in contact with the flow of the exhaust gas and secondly, to be thermally coupled directly or indirectly with the fluid of the loop (4).   11. Device according to any one of the preceding claims, characterized in that it comprises means (3) forming NOx trap integrated in means (5, 7) evaporators.   12. Device according to claim 11, characterized in that the means (5, 7) evaporators comprise a heat exchanger capable of thermally coupling the fluid of the loop (4) and the exhaust gas, and in that the means (3) ) forming a Nox trap are arranged on surfaces evaporator means (5, 7) able on the one hand to be in contact with the flow of exhaust gas and secondly, to be thermally coupled directly or indirectly with the fluid of the loop (4).   13. Motor vehicle, characterized in that it comprises a power recovery device according to any one of the preceding claims.