EP3585993B1 - Regenerative cooling system - Google Patents

Description

The present invention relates to a regenerative cooling system which constitutes, among other things, an improvement of the heat engine with transfer-expansion and regeneration which was the subject of patent application No. FR 15 51593 of February 25, 2015 owned by the applicant and the patent published on ¹ September 2016 under No. US 2016/0252048 A1 which also belongs to the applicant.

We know the regeneration Brayton cycle ordinarily implemented by means of centrifugal compressors and turbines.

According to this mode of implementation, said cycle leads to engines which deliver an efficiency which is substantially higher than that of spark ignition engines. Said efficiency is comparable to that of fast diesel engines. However, it is still lower than that of slow, very large displacement two-stroke diesel engines found, for example, in naval propulsion or stationary electricity production.

In addition to overall modest efficiency, engines with centrifugal compressors and regenerative Brayton cycle turbines deliver their best efficiency over a relatively narrow power and rpm range. In addition, their power modulation response time is long. Their field of application is in these various capacities limited and they are difficult to adapt to land transport and particularly to cars and heavy goods vehicles.

The thermal engine with transfer-expansion and regeneration which is the subject of patent application No. FR 15 51593 and documents FR3032235 and WO2016120560 has been designed to remedy these shortcomings. Said engine has the particularity of using the regenerated Brayton cycle no longer by means of centrifugal compressors and turbines, but by means of positive displacement machines or at least by means of a positive pressure regulator formed around a "cylinder". regulator ".

In the figures of patent application No. FR 15 51593 , it can be seen that each end of said expansion cylinder is closed by an expansion cylinder head. In addition, said cylinder accommodates a double-acting expansion piston to form two transfer-expansion chambers of variable volume. Said piston can move in the expansion cylinder to transmit work to a power output shaft via a connecting rod and a crankshaft known per se.

Among the advantages claimed by the invention which is the subject of patent application No. FR 15 51593 there is an efficiency of conversion of heat into work much higher than that of conventional reciprocating internal combustion engines whatever the principle, which leads, at the same work supplied, to a lower fuel consumption than that of said conventional engines and associated carbon dioxide emissions that are also lower.

So that these objectives can be achieved, as clearly stated in the patent application FR 15 51593 , at least three conditions must be met.

The first is that the volumetric regulator is effectively made up of a cylinder, which is not taught by the state of the art, which reports related machines. For example, the patent US 2003/228237 A1 of December 11, 2003 includes a compressor, a regeneration heat exchanger, a heat source and an expander, however, the latter is not a cylinder but what the inventors authors of said patent have called a "gerotor".

The second condition is that the inlet and outlet of the gases in the pressure reducing cylinder are regulated by duly phased intake and exhaust metering valves, which leads to the "pressure / volume" diagram to which a figure in the figure is devoted. patent application N ° FR 15 51593 .

The third condition is that the sealing device between the piston and the cylinder can operate at very high temperature.

It is noted that the heat transfer-expansion and regeneration engine described in patent application No. FR 15 51593 responds to this third condition by exhibiting an innovative air cushion segment made up of a continuous perforated inflatable and expandable ring housed in a ring groove in the pressure reducing piston. Said ring defines with said groove a pressure distribution chamber connected to a source of pressurized fluid.

This new sealing device and without direct contact with the expansion cylinder makes it possible to operate said cylinder at high temperature, while the intake and exhaust metering valves included in the cylinder heads which close said cylinder make it possible to maximize the efficiency of the cylinder. thermal engine with transfer-expansion and regeneration.

Purposely, the innovative sealing device based on an air cushion segment was placed in the patent application No. FR 15 51593 as a dependent claim on the main claim. It is easy to understand that by presenting his invention in this way, the inventor did not rule out that other sealing solutions could replace said segment, even if the latter is presented in said patent application as a key element of the segment. thermal engine with transfer-expansion and regeneration.

As is clearly stated in the patent application FR 15 51593 , in order for the efficiency of the transfer-expansion and regeneration heat engine to be as high as possible, the internal walls of the expansion cylinder must be brought to high temperature so that the hot gases introduced into said cylinder do not cool on contact with said cylinder. walls, or at least, are cooled as little as possible by said walls. This applies at least to the internal walls of the expansion cylinder proper, and to those of the cylinder heads with which said cylinder cooperates.

In accordance with the principle of thermodynamics of engines stated by Sadi Carnot, the patent application FR 15 51593 suggests that the efficiency of the transfer-expansion and regeneration heat engine is all the higher the higher the temperature of the gases introduced into the expansion cylinder.

This is why the patent application FR 15 51593 provides that the expansion cylinder, the cylinder heads of the expansion cylinder and the expansion piston of the transfer-expansion and regeneration heat engine can be made of materials resistant to very high temperatures such as ceramics based on alumina, zirconia or carbide silicon.

The hot parts and the high temperature components of the thermal transfer-expansion and regeneration engine have moreover been the subject of patents for improvements of said engine. In this regard, mention may be made of patent application No. FR 15 58585 of September 14, 2015 belonging to the applicant which deals with a double-acting regulator cylinder with adaptive support, said cylinder being able to operate at high temperature and be subjected to thermal expansions different from those of the transmission casing on which it is fixed. In the same register, we also note the patent application No. FR 15 58593 of September 14, 2015, also belonging to the applicant and which relates to a double-acting piston made up of a prestressed assembly, and capable of operating at high temperature.

Note that patent applications No. FR 15 58585 and No. FR 15 58593 which have just been cited offer very robust solutions for dealing with the cohabitation on the same device of parts brought to high temperature and parts brought to low temperatures.

In particular, the configurations proposed in said patents largely prevent the heat from migrating from the hot parts to the cold parts with which they cooperate. This preserves high efficiency for the transfer-expansion and regeneration heat engine.

On the other hand, the improvements set out in patent applications No. FR 15 58585 and No. FR 15 58593 do not change the fact that if the temperature of the gases introduced into the expansion cylinder of said engine is for example one thousand three hundred degrees Celsius, the temperature of the internal walls of said cylinder will be locally close to one thousand three hundred degrees Celsius, with an average temperature of said walls for example around a thousand degrees Celsius.

The temperature of said gases therefore directly determines the temperature to which the materials constituting the hot parts of the expansion cylinder of the transfer-expansion and regeneration heat engine must withstand. Thus, indirectly, the temperature resistance of said materials determines the maximum efficiency accessible by said motor.

It should also be noted that the materials that can withstand the very high temperatures in question are relatively few in number to the extent that they must also offer high mechanical resistance at these same said temperatures, in addition to being resistant to corrosion. and oxidation.

Said materials are mainly ceramics such as alumina, zirconia, silicon carbide or silicon nitride. These materials are hard and difficult to machine. Consequently, the cost price of the finished parts is relatively high, which is a brake on the adoption by the automotive industry of the transfer-expansion and regeneration heat engine which is the subject of the patent application. FR 15 51593 . In fact, since said industry is aimed at the mass market, it is highly sensitive to the manufacturing cost price, which must remain as low as possible.

The ideal would therefore be for the internal walls of the expansion cylinder of said engine to remain maintained at a maximum temperature of for example seven to nine hundred degrees Celsius. Indeed, at such temperatures, materials more common and less expensive to produce and to machine than ceramics such as cast iron or stainless or refractory steels can be used to manufacture said pressure reducing cylinder. This also applies to the cylinder heads and their respective plenums and ducts which cooperate with said cylinder.

However, it is imperative, on the one hand, to avoid lowering the temperature of the hot gases admitted into the expansion cylinder of the transfer-expansion and regeneration heat engine and, on the other hand, to let the heat escape in pure loss. of said gases through cooler walls of said cylinder in contact with which said gases are placed. Indeed, these two actions would have the damaging consequence of significantly reducing the final efficiency of the transfer-expansion and regeneration heat engine.

In the current state of the art and technique, it is therefore understood that a choice must be made between a heat engine with transfer-expansion and regeneration with very high efficiency but expensive and complex to produce, and an engine based on the same principle. but resorting to inexpensive materials to produce, and this at the cost of a great sacrifice in yield, the latter being significantly reduced. This is a dilemma.

• De réduire significativement la température des parois internes du cylindre détendeur et de ses culasses du moteur thermique à transfert-détente et régénération objet de la demande de brevet FR 15 51593 , ceci permettant de recourir à des matériaux à faible prix de revient pour fabriquer ledit cylindre et lesdites culasses sans réduire de façon significative le rendement total dudit moteur thermique ;
• D'autoriser une température d'entrée des gaz dans le cylindre détendeur supérieure à celle que pourraient supporter - en l'absence du système de refroidissement régénératif selon l'invention - des matériaux chers et complexes comme les céramiques ;
• De conférer au moteur à thermique à transfert-détente et régénération objet de la demande de brevet FR 15 51593 un rendement énergétique final supérieur à celui accessible au même dit moteur avec des matériaux chers et complexes comme les céramiques, avec des matériaux à faible prix de revient.

It is to get out of this dilemma that the regenerative cooling system according to the invention allows, according to a particular embodiment:

• Significantly reduce the temperature of the internal walls of the expansion cylinder and its cylinder heads of the transfer-expansion and regeneration heat engine which is the subject of the patent application FR 15 51593 , this making it possible to use materials at low cost to manufacture said cylinder and said cylinder heads without significantly reducing the total efficiency of said heat engine;
• To allow a gas inlet temperature in the pressure reducing cylinder higher than that which could withstand - in the absence of the regenerative cooling system according to the invention - expensive and complex materials such as ceramics;
• To give the thermal engine with transfer-expansion and regeneration which is the subject of the patent application FR 15 51593 a final energy efficiency higher than that accessible to the same said motor with expensive and complex materials such as ceramics, with materials at low cost.

It is understood that the regenerative cooling system according to the invention is mainly intended for the transfer-expansion and regeneration heat engine which is the subject of the patent application. FR 15 51593 belonging to the applicant.

However, said system can also be applied without restriction to the regulator of any other regenerating Brayton cycle engine, whether said regulator is of the centrifugal, positive-displacement or some other type, and provided that it cooperates with a regenerator of some kind. type whatever.

The other characteristics of the present invention have been described in the description and in the secondary claims dependent directly or indirectly on the main claim.

• Au moins une enceinte de refroidissement qui enveloppe en tout ou partie le détendeur de gaz et/ou la source de chaleur et/ou un conduit d'admission des gaz chauds qui relie ladite source audit détendeur, tandis qu'est laissé un espace de circulation des gaz entre ladite enceinte d'une part, et/ou ledit détendeur et/ou ladite source et/ou ledit conduit d'autre part ;
• Au moins un port d'entrée d'enceinte qui est directement ou indirectement relié à la sortie du détendeur de gaz et par lequel tout ou partie du gaz travaillant expulsé dudit détendeur via ladite sortie peut pénétrer dans l'espace de circulation des gaz ;
• Au moins un port de sortie d'enceinte qui est directement ou indirectement relié au conduit basse-pression de régénération et via lequel le gaz travaillant peut sortir de l'espace de circulation des gaz avant d'être introduit dans ledit conduit basse-pression.

The regenerative cooling system according to the present invention is provided for a regenerative heat engine, the latter comprising at least one regeneration heat exchanger which has a high-pressure regeneration duct in which circulates therein a working gas which has been preheated. previously compressed by a compressor, while on leaving said conduit said gas is superheated by a heat source before being introduced into a gas regulator in which it is expanded to produce work on a power output shaft, said gas then being expelled at the outlet of the gas regulator and then introduced into a low-pressure regeneration duct that the regeneration heat exchanger presents, said gas - by circulating in said duct - yielding a large part of its residual heat to the circulating working gas in the high-pressure regeneration duct, said system comprising:

• At least one cooling chamber which surrounds all or part of the gas regulator and / or the heat source and / or a hot gas inlet duct which connects said source to said regulator, while a circulation space is left gases between said enclosure on the one hand, and / or said pressure reducing valve and / or said source and / or said duct on the other hand;
• At least one enclosure inlet port which is directly or indirectly connected to the outlet of the gas regulator and through which all or part of the working gas expelled from said regulator via said outlet can enter the gas circulation space;
• At least one enclosure outlet port which is directly or indirectly connected to the low-pressure regeneration duct and via which the working gas can leave the gas circulation space before being introduced into said low-pressure duct.

The regenerative cooling system according to the present invention comprises an enclosure inlet port which is connected to the outlet of the gas regulator by an enclosure inlet duct, the effective section of which is regulated by a flow rate regulating valve. .

The regenerative cooling system according to the present invention comprises an enclosure outlet port which is connected to the regeneration low-pressure duct by an enclosure outlet duct, the effective section of which is regulated by a flow control valve.

The regenerative cooling system according to the present invention comprises an outlet of the gas regulator which is connected to the low-pressure regeneration duct by an enclosure bypass duct.

The regenerative cooling system according to the present invention comprises an effective section of the enclosure bypass duct which is regulated by a flow control valve.

The regenerative cooling system according to the present invention comprises an exterior of the cooling enclosure which is coated with a heat shield.

The description which will follow with reference to the appended drawing and given by way of non-limiting example will make it possible to better understand the invention, the characteristics that it presents, and the advantages that it is likely to provide:
Figure 1 is a schematic representation in side view of the regenerative cooling system according to the invention as it can be implemented on the heat engine with transfer-expansion and regeneration object of patent application No. FR 15 51593 belonging to the applicant, and according to a variant of said system according to which the outlet of the gas regulator is connected to the low-pressure regeneration duct by an enclosure bypass duct, while the effective section of said bypass duct and of the outlet duct chamber is regulated by a flow control valve.

DESCRIPTION OF THE INVENTION :

We showed in figure 1 the regenerative cooling system 100, various details of its components, its variants, and its accessories.

As the said figure 1 , the regenerative cooling system 100 is provided for a regenerative heat engine 1, the latter comprising at least one regeneration heat exchanger 5 which has a high-pressure regeneration duct 6 in which circulates in order to be preheated therein a working gas 81 which has been previously compressed by a compressor 2.

On leaving the high-pressure regeneration duct 6, said gas 81 is superheated by a heat source 12 before being introduced into a gas regulator 78 in which it is expanded to produce work on a power output shaft 17. .

The working gas 81 is then expelled at the outlet of the gas regulator 78 and then introduced into a low-pressure regeneration duct 7 which the regeneration heat exchanger 5 has, said gas 81 - by circulating in said duct 7 - yielding a large part of its residual heat to the working gas 81 circulating in the high-pressure regeneration duct 6.

It is in this context clearly illustrated in figure 1 that the regenerative cooling system 100 according to the invention comprises at least one cooling enclosure 79 which surrounds all or part of the gas pressure reducer 78 and / or the heat source 12 and / or a hot gas inlet duct 19 which connects said source 12 to said regulator 78, while a space for the circulation of gases 80 is left between said enclosure 79 on the one hand, and / or said regulator 78 and / or said source 12 and / or said duct 19 of on the other hand, the working gas 81 being able to circulate in said space 80.

It is noted that the cooling enclosure 79 can be made of stamped or hydro-formed stainless steel sheet, and possibly be made in several parts assembled together by welding, screwing, or riveting, said enclosure then being able to be fixed directly or indirectly on the components 78, 12, 19 that it envelops.

The figure 1 illustrates that the regenerative cooling system 100 according to the invention further comprises at least one enclosure inlet port 82 which is directly or indirectly connected to the outlet of the gas regulator 78 and through which all or part of the working gas 81 expelled from said regulator 78 via said outlet can enter the gas circulation space 80.

Always in figure 1 , it will be noted that the regenerative cooling system 100 according to the invention also comprises at least one enclosure outlet port 83 which is directly or indirectly connected to the low-pressure regeneration duct 7 and via which the working gas 81 can exit from the gas circulation space 80 before being introduced into said low-pressure duct 7.

It will be noted that preferably, the cooling enclosure 79 surrounds the gas regulator 78 and / or the heat source 12 and / or the hot gas inlet duct 19 in a sealed manner so that the working gas 81 cannot enter. in the gas circulation space 80 only through the enclosure inlet port 82, while said gas 81 can only leave said space 80 through the enclosure outlet port 83.

According to an alternative embodiment of the regenerative cooling system 100 according to the invention shown in figure 1 , the enclosure inlet port 82 can be connected to the outlet of the gas regulator 78 by an enclosure inlet duct 84, the effective section of which is regulated by a flow control valve 85, the latter being able to - depending on its position - prohibit, leave free, or restrict the flow of the gas working 81 in said duct 84.

As another variant always shown in figure 1 , the enclosure outlet port 83 can be connected to the low-pressure regeneration duct 7 by an enclosure outlet duct 86, the effective section of which is regulated by a flow rate regulating valve 85, the latter being able to - as a function of its position - prohibit, leave free, or restrict the circulation of the gas working 81 in said enclosure outlet duct 86.

The figure 1 also illustrates that another variant of the regenerative cooling system 100 according to the invention consists in that the outlet of the gas regulator 78 can be connected to the low-pressure regeneration duct 7 by an enclosure bypass duct 87 which allows the working gas 81 expelled at the outlet of the gas regulator 78 to go directly from said outlet to the low-pressure regeneration duct 7 without passing through the gas circulation space 80.

According to the latter variant, the effective section of the enclosure bypass duct 87 can optionally be adjusted by a flow rate regulating valve 85, the latter being able - depending on its position - to prohibit, leave free, or restrict the flow of gas. working 81 in said bypass duct 87.

In figure 1 , it is noted that advantageously the outside of the cooling enclosure 79 can be coated with a heat shield 88 which can be made of any heat-insulating material known to those skilled in the art and which can - in addition to the enclosure cooling 79 - coat the various ducts and hot components that make up the regenerative heat engine 1.

It is noted that in this case, said heat shield 88 is provided to prevent any excessive heat loss which is unfavorable to the efficiency of the regenerative heat engine 1.

OPERATION OF THE INVENTION :

The operation of the regenerative cooling system 100 according to the invention is easily understood from the view of the figure 1 .

To detail said operation, we will retain here the embodiment of the regenerative cooling system 100 according to the invention when the regeneration engine 1 to which it is applied consists of the heat engine with transfer-expansion and regeneration which is the subject of the request for patent N ° FR 15 51593 dated February 25, 2015 belonging to the applicant.

As seen on the figure 1 , the regeneration engine 1 here comprises a two-stage compressor 2 which consists in particular of a low-pressure compressor 35 which sucks in the gas working 81 in the atmosphere via a compressor inlet duct 3, the outlet of said compressor low-pressure 35 being connected to the inlet of a high-pressure compressor 36 via a compressor intercooler 37.

The figure 1 illustrates that at the outlet of the high-pressure compressor 36, the working gas 81 is expelled into the high-pressure regeneration duct 6 which comprises the regeneration heat exchanger 5 which in this case is a counter-current heat exchanger 41 known per se. We will assume here the assumption that the working gas 81 is expelled from the high-pressure compressor 36 at a pressure of twenty bars and at a temperature of two hundred degrees Celsius.

By circulating in the high-pressure regeneration duct 6, the working gas 81 is preheated to a temperature of six hundred and fifty degrees Celsius by the hot working gas 81 which circulates in the adjacent low-pressure regeneration duct 7.

For simplicity, consider that the efficiency of the regeneration heat exchanger 5 is one hundred percent. This implies that the working gas 81 which circulates in the low-pressure regeneration duct 7 enters the latter at a temperature of six hundred and fifty degrees Celsius and leaves said duct 7 at a temperature of two hundred degrees Celsius before be released into the atmosphere via the engine outlet duct 33, while the working gas 81 which circulates in the high-pressure regeneration duct 6 enters the latter at a temperature of two hundred degrees Celsius and leaves it at a temperature of two hundred degrees Celsius. temperature of six hundred and fifty degrees Celsius.

Leaving the high-pressure regeneration duct 6, said working gas 81 is then superheated to one thousand four hundred degrees Celsius by the heat source 12 which - according to this exemplary embodiment - consists of a fuel burner 38.

On leaving said burner 38, the working gas 81 is conveyed through a hot gas inlet pipe 19 to the gas expander 78 which is none other than the expansion cylinder 13 of the heat engine with transfer-expansion and regeneration object of patent application N ° FR 15 51593 .

It should be noted that the hot gas inlet duct 19 is preferably made of ceramic with high temperature resistance until it is connected to an expansion cylinder head 14 covering one or the other end of the expansion cylinder 13. Thus , the temperature of said duct 19 remains approximately equal to one thousand four hundred degrees Celsius so that the working gas 81 circulating in said duct 19 maintains its temperature throughout its journey.

So, as illustrated in figure 1 , each end of the expansion cylinder 13 is capped with an expansion cylinder head 14 so that with a double-acting pressure reducing piston 15 are defined two transfer-expansion chambers 16. It is also noted that each cylinder head comprises a metering valve of intake 24 and an exhaust metering valve 31.

Thanks to the regenerative cooling system 100 according to the invention, the heat transfer-expansion and regeneration engine being hot, the expansion cylinder 13 and the expansion cylinder heads 14 are maintained at a temperature in the region of seven hundred degrees Celsius. This makes it possible to produce said cylinder 13 and said cylinder heads 14 in a material that is less expensive and more common than ceramic, such as stainless steel or ferritic cast iron with silicon.

The double-acting expansion piston 15 is for its part, and according to this non-limiting example of embodiment of the regenerative cooling system 100 according to the invention, made of silicon nitride. The average operating temperature of said piston 15 is of the order of eight hundred degrees Celsius.

We notice in figure 1 that said piston 15 is connected by mechanical transmission means 19 to a power output shaft 17, said means 19 being in particular constituted by a connecting rod 42 articulated around a crank 43.

The working gas 81 brought to a pressure of twenty bars and to a temperature of one thousand four hundred degrees Celsius is therefore introduced into one or the other transfer-expansion chamber 16 by the corresponding inlet metering valve 24.

Passing through the orifice kept open by the inlet metering valve 24, said gas 81 begins to cool slightly, in particular in contact with the internal walls of the cylinder head 14 which it passes through, and the internal walls of the cylinder head. the transfer-expansion chamber 16 into which it is introduced with the aim of being relaxed there by the double-acting pressure reducing piston 15. Said walls are - as we have seen previously - maintained at seven hundred degrees Celsius by the regenerative cooling system 100.

At this stage, we will assume that the working gas 81 loses an average of one hundred degrees Celsius by licking the internal walls of the expansion valve cylinder head 14, and those of the transfer-expansion chamber 16. As a result, the temperature of the gas working 81 fell during its transfer from the hot gas inlet duct 19 to the transfer-expansion chamber 16 to pass from one thousand four hundred degrees Celsius to one thousand three hundred degrees Celsius.

When the desired quantity of working gas 81 has actually been introduced into the transfer-expansion chamber 16 by the corresponding intake metering valve 24, the latter closes, and the double-acting pressure reducing piston 15 expands said gas 81. In doing so , said pin 15 collects the work produced by the expansion of said gas 81, and communicates said work to the power output shaft 17 in particular via the connecting rod 42 and the crank 43.

Once the working gas 81 has been expanded by the double-acting pressure reducing piston 15, the pressure of said gas 81 has dropped to about one bar absolute. The same is true for the temperature of said gas 81 which has gone from one thousand three hundred degrees Celsius to five hundred and fifty degrees Celsius.

The double-acting regulator piston 15 having reached its Bottom Dead Center, the exhaust metering valve 31 opens and said piston 15 expels said gas 81 into the enclosure inlet duct 84 which conveys said gas 81 to speaker input port 82.

The working gas 81 then enters the gas circulation space 80 and then goes via this space to the enclosure outlet port 83. In doing so, said gas 81 licks the hot outer walls of the expansion cylinder 13 and the cylinder heads. expansion cylinder 14. Said outer walls have been provided wholly or partly rough and / or dotted with geometric patterns in order to produce a convective forcing forcing the working gas 81 to take more or less heat from said walls when said gas 81 circulates in contact with said walls.

In addition, the internal geometry of the cooling enclosure 79 and / or the external geometry of the expansion cylinder 13 and / or the external geometry of the expansion cylinder heads 14 can advantageously form channels which force all or part of the working gas 81 to following a route or several simultaneous routes to go from the enclosure entry port 82 to the enclosure exit port 83 via the gas circulation space 80.

It is understood that the double strategy of convective forcing and forced route of the working gas 81 makes it possible to choose, first of all, the heat export zones from the hot external walls of the expansion cylinder 13 and the cylinder heads of the expansion cylinder 14 towards said gas 81, on the second hand, the chronological order of sweeping of said zones by said gas 81, and on the third and final part, the intensity of the convective forcing along the route of said gas 81.

In any event, during its journey through the cooling enclosure 79, the temperature of the working gas 81 subtracts heat from the hot outer walls of the expansion cylinder 13 and the expansion cylinder heads 14 to the point that the temperature of said gas 81 gradually goes from five hundred and fifty degrees Celsius to six hundred and fifty degrees Celsius. In doing so and in relation to the strategy of convective forcing and route chosen for said gas 81, the latter homogenizes the temperature of the expansion cylinder 13 and of the expansion cylinder heads 14, said temperature being maintained in the vicinity of seven hundred degrees Celsius.

The working gas 81 having reached its new temperature of six hundred and fifty degrees Celsius, said gas 81 arrives at the enclosure outlet port 83 and joins the low-pressure regeneration duct 7 via the enclosure outlet duct 86.

As understood from reading the foregoing, by circulating in the low-pressure regeneration duct 7 and before being released into the atmosphere via the engine outlet duct 33, the working gas 81 expelled from the Enclosure outlet port 83 transfers a large portion of its heat to the working gas 81 which circulates in the adjacent high-pressure regeneration duct 6.

Ultimately and thanks to the regenerative cooling system 100 according to the invention, the heat extracted from the expansion cylinder 13 and the expansion cylinder heads 14 to maintain them at a temperature of the order of seven hundred degrees Celsius is in no way dissipated in vain.

Indeed, said heat is reintroduced into the thermodynamic cycle of the regenerative heat engine 1 to replace part of the heat to be supplied by the fuel burner 38 to bring the working gas 81 to a temperature of one thousand four hundred. degrees Celsius before the latter is directed towards the expansion cylinder 13 and then introduced into the transfer-expansion chambers 16.

We notice in figure 1 the enclosure bypass duct 87 which comprises a flow rate adjustment valve 85. It is also noted in figure 1 that the enclosure outlet duct 86 also comprises a flow rate adjustment valve 85. These two said Valves 85 constitute an alternative embodiment of the regenerative cooling system 100 according to the invention and are provided to regulate the temperature of the expansion cylinder 13 and of the cylinder heads of the expansion cylinder 14.

Indeed, if said temperature is too high, the flow rate control valve 85 of the enclosure bypass duct 87 closes said bypass duct 87 while the flow rate regulator valve 85 of the enclosure outlet duct 86 opens said. outlet duct 86. This has the effect of forcing the working gas 81 expelled from the transfer-expansion chambers 16 by their respective exhaust metering valve 31 to pass through the gas circulation space 80 to join the low-pressure duct regeneration 7.

If, on the contrary, the temperature of the expansion cylinder 13 and of the expansion cylinder heads 14 is too low, the flow rate adjustment valve 85 of the enclosure bypass duct 87 opens said bypass duct 87 while the flow rate adjustment valve 85 of the enclosure outlet duct 86 closes said outlet duct 86. This has the effect of preventing the working gas 81 expelled from the transfer-expansion chambers 16 by their respective exhaust metering valve 31 from passing through the exhaust space. circulation of gases 80 to reach the low-pressure regeneration duct 7. Said gas 81 therefore joins said duct 7 directly, via the enclosure bypass duct 87.

It will be understood that in practice, the flow rate control valves 85 are rarely either fully open or fully closed, and that said valves 85 can be kept ajar to regulate the temperature of the expansion cylinder 13 and of the expansion cylinder heads 14 without abrupt variation. working gas flow rate 81 circulating in the gas circulation space 80.

It is also understood that the regulation of said temperature requires a control device formed, for example, of at least one temperature sensor and a microcontroller known per se, which make it possible to control servomotors of any type whatsoever which each actuates a flow rate adjustment valve 85 on opening or closing.

According to a particular embodiment of the regenerative cooling system 100 according to the invention, the flow rate control valves 85 can also be connected to one another by a mechanical connection to share the same booster. In this case, said connection guarantees that when the first said valve 85 is closed the second is open, and vice versa.

It can easily be deduced from the foregoing that the regenerative cooling system 100 according to the invention provides numerous advantages, in particular to the use of the heat engine with transfer-expansion and regeneration which is the subject of patent application No. FR 15 51593 belonging to the applicant.

As a first advantage, it is no longer necessary to make the pressure reducing cylinder 13 and the pressure reducing cylinder heads 14 from ceramic material such as, for example, silicon carbide. Indeed, this type of material is notoriously expensive to produce because of its great hardness making it difficult to machine using cutting tools or conventional rectification. Thanks to the regenerative cooling system 100 according to the invention, it is possible to replace said ceramic with cast iron or stainless steel. This greatly reduces the cost of manufacturing the heat transfer-expansion and regeneration engine, which is decisive, in particular for said engine to be able to access the automobile market.

As a second advantage, the expansion cylinder 13 and the expansion cylinder heads 14 being cooler, it is possible to use materials with very low thermal conductivity and high mechanical resistance to compression such as quartz to produce the pillars. recesses of the double-acting regulator cylinder with adaptive support subject of patent application no. FR 15 58585 of September 14, 2015 belonging to the applicant. Indeed, if quartz is not compatible with a temperature of one thousand three hundred degrees Celsius, it is perfectly compatible with a temperature of seven hundred degrees Celsius. Let us recall here that the double-acting regulator cylinder with adaptive support in question constitutes one of the key improvements of the heat engine with transfer-expansion and regeneration.

As a third advantage, the expansion valve cylinder heads 14 being maintained at seven hundred degrees Celsius, they can receive pre-existing silicon nitride valves, compatible with these temperature levels. Such valves have for example been developed by the company "NGK" and have been the subject of research on their industrialization at low cost in particular within the framework of the project N ° G3RD-CT-2000-00248 entitled "LIVALVES", financed in within the framework of the fifth European FP5-GROWTH framework program.

As a fourth advantage, with an inner wall temperature of expansion cylinder 13 maintained in the vicinity of seven hundred degrees Celsius, the air cushion segment as provided in patent application No. FR 15 51593 belonging to the applicant can be made of a superalloy which is durably resistant to these temperature levels, without risk for said segment of being subjected to a temperature significantly higher than said seven hundred degrees Celsius, in particular when the heat engine with transfer-expansion and regeneration is stopped and before the latter has cooled.

As a fifth advantage, applied to the thermal engine with transfer-expansion and regeneration which is the subject of patent application No. FR 15 51593 , the regenerative cooling system 100 according to the invention makes it possible to limit the temperature to which the heat shields 88 which surround the expansion cylinder 13 and the expansion cylinder heads 14. In fact, the cooling enclosure 79 is inserted between between said screens 88 on the one hand, and said cylinder 13 and said cylinder heads on the other hand. The cost price and the durability of said screens 88 are thus improved to a considerable extent.

These advantages are obtained without prejudice to the final energy efficiency of the heat transfer-expansion and regeneration engine.

On the contrary, the regenerative cooling system 100 according to the invention makes it possible to decouple the existing relationship according to patent application No. FR 15 51593 between the temperature resistance of the constituent materials of the expansion cylinder 13 and the expansion cylinder heads 14 on the one hand, and the temperature of the working gas 81 leaving the fuel burner 38 on the other hand.

In a way, thanks to the regenerative cooling system 100 according to the invention, it is conceivable to increase the temperature of the working gas 81 leaving the fuel burner 38 to increase the final efficiency of the heat engine with transfer-expansion and regeneration, and this, without compromising the temperature resistance of the main components which constitute said engine.

It should be noted that, in addition to the thermal engine with transfer-expansion and regeneration, which is the subject of patent application No. FR 15 51593 , the regenerative cooling system 100 according to the invention can advantageously be applied to any other regenerative heat engine 1 whose configuration and temperature characteristics are compatible with said system 100.

Claims (6)

1. A regenerative cooling system (100) designed for a regeneration heat engine (1), the latter comprising at least one regeneration heat exchanger (5) having a high-pressure regeneration duct (6) in which a working gas (81) circulates to be preheated there, having been previously compressed by a compressor (2), wherein said gas (81), while leaving said duct (6), is superheated by a heat source (12) before being introduced into a gas expander (78) in which it is expanded to perform work on a power output shaft (17), said gas (81) being then expelled at the outlet of the gas expander (78) and then introduced into a low-pressure regeneration duct (7) of the regeneration heat exchanger (5), said gas (81) - by circulating in said duct (7) - surrendering a large portion of its residual heat to the working gas (81) circulating in the high-pressure regeneration duct (6), said system (100) being characterized in that it comprises:

   • at least one cooling chamber (79) which surrounds entirely or partly the gas expander (78) and / or the heat source (12) and / or a hot gas intake duct (19) which connects said source (12) to said expander (78), while leaving opened a gas circulation space (80) between said chamber (79) on the one hand, and / or said expander (78) and / or said source (12) and / or said duct (19) on the other hand;

   • at least one chamber inlet port (82) which is directly or indirectly connected to the outlet of the gas expander (78) and by which some or all of the working gas (81) expelled from said expander (78) via said outlet can enter into the gas circulation space (80);

   • at least one chamber outlet port (83) which is directly or indirectly connected to the low-pressure regeneration duct (7) and via which the working gas (81) can leave the gas circulation space (80) before being introduced into said low-pressure duct (7).
2. The regenerative cooling system as claimed in claim 1, characterized in that the chamber inlet port (82) is connected to the outlet of the gas expander (78) by a chamber inlet duct (84) whose effective cross-section is regulated by a flow control valve (85).
3. The regenerative cooling system as claimed in claim 1, characterized in that the chamber outlet port (83) is connected to the low-pressure regeneration duct (7) by a chamber outlet duct (86) whose effective cross-section is regulated by a flow control valve (85).
4. The regenerative cooling system as claimed in claim 1, characterized in that the outlet of the gas expander (78) is connected to the low-pressure regeneration duct (7) by a chamber bypass duct (87).
5. The regenerative cooling system as claimed in claim 4, characterized in that the effective cross-section of the chamber bypass duct (87) is regulated by a flow rate control valve (85).
6. The regenerative cooling system as claimed in claim 1, characterized in that the exterior of the cooling chamber (79) is coated with a heat shield (88).

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