FR2712850A1 - Device for generating thermal flux for heating and cooling of electric vehicle - Google Patents

Abstract

The thermal flux generator has a first reactor (1) containing a reactive solid that combines with a reactive fluid in a reversible exothermic reaction. The reactive fluid is generated (2) in an endothermic reaction. The reactive fluid is coupled through conduits (3,4) to transfer the fluid to and from the solid reactor. A second fluid circulation has a working fluid in thermal exchange (5,7) with the reactor and with the generator (6,8). The working fluid is in thermal exchange (13,17) with streams of air. The air flow is assisted by fans (14,18). One air stream (F) is directed into the interior of the vehicle. The directions of circulation of the working fluid can be reversed to determine whether the interior of the vehicle is heated or cooled.

Description

-Device and method for the production of heat fluxes in an electric vehicle
The invention relates to the use, for the production of heat fluxes in an electric vehicle, of energy storage systems calling upon chemical reactions or phenomena of adsorption or absorption, such as those described in EP -A-0 307 297 and EP-AO 382 586 for example.

The hut of the invention is to propose concrete solutions in this field in the process of exploration.

 The ir.vention relates in particular to a device for the production of heat fluxes in an electric vehicle, comprising a first reactor containing a first solid reagent capable of combining with a reactive fluid by a reversible exothermic reaction, a source of reactive fluid suitable for producing said reactive fluid by a reversible endothermic miqe phenomenon, means for transferring the reactive fluid from said source to said first reactor and vice versa., a heat transfer fluid circuit comprising a first branch in thermal contact with the first reactor, a second branch in thermal contact with the source of reactive fluid, a third branch suitable for exchanging heat with a stream of air intended to be sent into the passenger compartment of the vehicle, a fourth branch suitable for exchanging heat with an environment external to the 'hc-titacle, and switching means suitable for establishing at c: hoix at least two configur separate ations of the heat transfer fluid circuit, namely a first dan configuration. which this circuit is divided into two independent sub-circuits, one containing the first and fourth branches and the other containing the second and third branches, and a second configuration in which the first, second, third and fourth branches are in series.

Other characteristics, complementary or alternative, of the invention are set out below - Lc. reactive fluid source is an evaporator.

- The. source of reactive fluid is a second reactor in which 1 takes place a reversible endothermic reaction giving rise to said reactive fluid and to a second solid reactant.

- Said external environment is the atmosphere.

- In the second configuration, the heat transfer fluid flows successively through the first, third, second and fourth branches.

- The switching means comprise a first four-way valve suitable for putting the outputs of the first and second branches in communication respectively with the inputs of the fourth and third branches in the first configuration and with the inputs of the third and fourth branches in the second configuration.

- The switching means comprise a second four-way valve capable of cooperating with the first four-way valve to establish either a third configuration of the heat transfer fluid circuit in which a third sub-circuit contains the second and fourth branches excluding the first and third branches, ie a fourth configuration of the heat transfer fluid circuit in which a fourth sub-circuit contains the second and third branches excluding the first and fourth branches.

- The. second four-way valve is a mixing valve suitable for mixing, in the second configuration, a fraction of the flow of fluid from the fourth branch to the fluid from the third branch to introduce the mixture into the second branch.

 The invention also relates to a method for air conditioning the passenger compartment of an electric vehicle using the device defined above, the first and second configurations being established respectively for cooling and for heating the passenger compartment during vehicle running.

The third and fourth configurations can then be established respectively to dissipate in the atmosphere and in the h-titacle the heat released by the source of reactive gas lorC from the regeneration of the device when the vehicle is stopped.

The characteristics and advantages of the invention will be explained in more detail in the description below, with reference to the appended drawings, in which - Figures la, lb, lc and ld are diagrams showing a device according to the first mode of realization of the invention, in the four configurations of the coolant circuit; - Figure le, similar to Figure lb, illustrates a variant of this device.

The device illustrated in FIGS. 1a to 1d, intended for the air conditioning of an electric vehicle, uses an energy storage system comprising a reactor 1 and an evaporator-condenser 2 connected together by a pipe 3 on which a valve is interposed commanded 4. When the valve 4 is open, the system can operate according to a phase of production or release of energy, and according to a phase of regeneration or storage of energy. In the production phase, a reactive fluid vaporizes in the evaporator 2, consuming heat. The cold produced can. be evacuated by a heat transfer fluid circulating through the evaporator in a line 6. The vaporized fluid is transferred by line 3 into the reactor 1 where it combines, by a chemical reaction (or absorption) or by a physical-physical phenomenon. chemical such as adsorption, with a solid reagent present in the reactor. The heat released by this exothermic reaction can be removed by a heat transfer fluid circulating through the reactor in a pipe 5.

In. the regeneration phase, heat is supplied to the reactor 1 by a heat source not shown. The reactive fluid dissociates from the solid reactant and is returned to the evaporator 2, which then plays the role of condenser and gives off heat which can be evacuated by the calcined fluid, the carrier circulating in line 6.

 As known per se, the element 2 serving sometimes as an evaporator, sometimes as a condenser, can be replaced by a separate evaporator and condenser forming with the reactor 1 a triangular circuit in which the pipe connecting the reactor and the evaporator is closed during regeneration.

In a manner also known per se, the evaporator / condenser 2 can be replaced by a second reactor containing a solid reagent similar to that of reactor 1 and which can be combined with the reactive gas by a reversible exothermic reaction, the equilibrium pressure of the reaction being higher for the second reactor than for reactor 1, for a given temperature.

The lines 5 and 6, provided with respective circulation pumps 7 and 8, are connected via two four-way vanr.es 9 and 10 to two other lines 11 and 12 to form a configurable heat transfer fluid circuit. variable. The pipe 11 passes through a heat exchanger 13 interposed on the path of an air current, which is produced by a fan 14 and can be sent in known manner to different places in the passenger compartment of the vehicle, according to arrows F, through respective pipes 16. The branch 12 passes in the same way through a heat exchanger 17 placed outside the passenger compartment and which can be swept by a current of air produced by a fan 18. The valve 9 is connected to the downstream ends of the branches 5 and 6 and the valve 10 at their upstream ends.

Figure la illustrates the configuration of the heat transfer fluid circuit used in summer for cooling the he.bitacle. The valve 9, in a position a, connects the downstream ends of the pipes 5 and 6 to the upstream ends of the pipes 12 and 11 respectively, while the valve 10, in its position a, connects the upstream ends of the branches 5 and. 6 at the downstream ends of the branches 12 and 11 respectively. The heat transfer fluid circuit is therefore divided into two independent sub-circuits, in which the fluid circulates under the effect of the pumps 7 and 8 respectively. The fluid circulating in the sub-circuit 6, 11 is cooled by the evaporator 2 and in turn cools the air flow produced by the fan 14, thus ensuring cooling. of the passenger compartment. The heat released by the reactor 1 is evacuated to the atmosphere via the circulating fluid. in the sub-circuit 5, 12, of the heat exchanger 17 and a current of air produced by the fan 18.

In the configuration illustrated in FIG. 1b, used for heating the passenger compartment in winter, the valve 10 retains its position a while the valve 9 is in a position d in which it connects the downstream ends of the branches 5 and 6 at the upstream ends of the branches 11 and 12 respectively. Under these conditions, the four branches 5, 11, 6 and 12 are. arranged in series and are traversed in this order by the heat transfer fluid. The heat transfer fluid heated by the reactor 1 in turn heats the air flow produced by the fan 14 and sent into the passenger compartment. However, it retains a temperature significantly higher than that of the ambient air in cold weather. Its use as a heat source for the evaporator avoids the icing problems encountered when atmospheric air is used for this purpose. The cold heat transfer fluid then passes through the heat exchanger 17, the fan 18 being out of service, before being returned to the reactor 1.

The cold and heat production modes using the configurations of FIGS. 1a and 1b deplete the energy stored in the system 1-4, requiring regeneration.

This regeneration is carried out by adding heat to the reactor 1, for example by means of electrical resistors not shown provided in the latter and which are supplied with current during the recharging of the traction batteries of the vehicle.

The configuration illustrated in Figure lc can be used for regeneration in summer. The valve 9 is in position d, and the valve 10 is also in a position b connecting. the upstream end of the pipe 6 and the downstream end of] .a pipe 12. The heat transfer fluid then circulates in a sub-circuit composed of these two branches, under the action of the pump 8, thus dissipating in the atmosphere, through the heat exchanger 17 and the air stream produced by the fan 18, the heat given off by the evaporator 2 operating as a condenser. The pump 7 being stopped, no fluid circulates in the branches 5 and 11.

In the configuration according to FIG. 1d, used for regeneration in winter, the valves 9 and 10 are both in. their position a. The heat transfer fluid circulates under the action of the pump 8 in a sub-circuit composed of the brar.ches 6 and 11. The heat released by the condenser 2 is used to preheat the passenger compartment. The pump 7 is still stopped, so that no fluid circulates in the branches 5 and 12.

 The whole device is controlled by electronic means. 19. The device of Figures la to ld is simple in its structure. It can be fitted with a control panel placed on the dashboard of the vehicle and allowing. the user to select the different operating parameters.

As indicated, in the configuration according to FIG. 1b, the circulation in the evaporator 2 of the fluid heated by the reactor 1 avoids any risk of icing in the evaporator. However, for certain reactive / solid gas pairs, if the temperature of the heat transfer fluid arriving at the evaporator is too high, this results in an undesirable continuous increase in the temperatures in the evaporator and in the reactor.

To avoid this drawback, in the variant of the device illustrated in FIG. 1c, a four-way valve 10 is used a so-called mixing or mixing valve, such as that described in the French Patent Application.
No 93 07650 in the name of the Claimant. This valve comprises adjustment means allowing a continuous passage from a position a corresponding to FIG. 1a, in which the pipes 11 and 12 are connected respectively to the pipes 6 and 5, to a position d corresponding to FIG. 1c in which the line 12 is connected to line 6 and lines 5 and 11 are insulated. In the intermediate positions c, as illustrated in FIG. 1 a, variable fluid flow rates circulate, through the valve 10; from line 11 to line 6, from line 12 to line 5 and from line 12 to line 6. To maintain equal flow rates in the different branches, there is provided a bypass line 20 starting from the line 11, downstream of the exchanger 13, and leading to line 5, upstream of the reactor 1.

The adjustment of the mixing valve makes it possible to control the temperature of the fluid sent to the evaporator and therefore to stabilize the operation of the system.

Claims (10)

Claims 1. Device for the production of heat fluxes in an electric vehicle, comprising a first reactor (1) containing a first solid reagent capable of combining with a reactive fluid by a reversible exothermic reaction, a source (2) of reactive fluid suitable for producing said reactive fluid by a reversible endothermic phenomenon, means (3,4) for transferring the reactive fluid from said source to said first reactor and vice versa, a heat transfer fluid circuit comprising a first branch (5) in thermal contact. with the first reactor, a second branch (6) in thermal contact with the source of reactive fluid, a third branch (11) suitable for exchanging heat with a stream of air (F) intended to be sent into the 'he.bitacle of the vehicle, a fourth branch (12) capable of exchanging heat with an environment external to the passenger compartment, and switching means (9,10) capable of being chosen at least s two separate configurations of the heat transfer fluid circuit, namely a first configuration in which this circuit is divided into two independent sub-circuits, one containing the first and fourth branches (5,12) and the other containing the second and third branches (6,11), and a second configuration in which the first, second, third and fourth branches are in series. 2. Device according to claim 1, characterized in that the source of reactive fluid is an evaporator (2). 3. Device according to claim 1, characterized in that the source of reactive fluid is a second reactor in which a reversible endothermic reaction occurs giving rise to said reactive fluid and to a second solid reactant. 4. Air conditioning device according to one of the preceding claims, characterized in that said external environment is the atmosphere. 5. Device according to claim 4, characterized in that, in the second configuration, the heat transfer fluid flows successively in the first, third, second and fourth branches (5,11,6,12). 6. Device according to claim 5, characterized in that the switching means comprise a first four-way valve (9) adapted to put the outputs of the first and second branches (5,6) in communication respectively with the inputs of the fourth and third branches (12,11) in the first configuration and with the inputs of the third and fourth branches in the second configuration. 7. Device according to claim 6, characterized in that the switching means comprise a second four-way valve (10) adapted to cooperate with the first four-way valve to establish either a third configuration of the heat transfer fluid circuit in which a third sub-circuit contains the second and fourth branches (6,12) excluding the first and third branches (5,11), i.e. a fourth configuration of the heat transfer fluid circuit in which a fourth sub-circuit contains the second and third branches (6.11) excluding the first and fourth branches (5.12). 8. Device according to claim 7, characterized in that the second four-way valve (10) is a mixing valve suitable for mixing, in the second configuration, a fraction of the flow of fluid from the fourth branch (12) to the fluid from the third branch (11) to introduce the mixture into the second branch (6). 9. A method for air conditioning the passenger compartment of an electric vehicle using the device according to one of claims 4 to 8, the first and second configurations being established respectively for cooling and for heating the passenger compartment during the vehicle running. 10. Method according to claim 9 using the device according to one of claims 7 and 8, characterized in that the third and fourth configurations are established respectively to dissipate in the atmosphere and in the passenger compartment the heat released by the source ( 2) reactive gas during the regeneration of the device when the vehicle is stopped.