EP4100637A1

EP4100637A1 - Thermodynamic engine

Info

Publication number: EP4100637A1
Application number: EP21704723.2A
Authority: EP
Inventors: Gilles Brule
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-02-04
Filing date: 2021-02-04
Publication date: 2022-12-14
Also published as: WO2021156325A1; FR3106859A1; FR3106859B1

Abstract

The present invention relates to a thermodynamic engine which operates between two heat sources. A fluid passes alternately from a hot chamber 1 to a cold chamber 2, the passage from one chamber to the other taking place at constant pressure and without heat exchange. The hot chamber is filled with cold fluid at the intermediate pressure (PI). The cold fluid will receive heat via the hot source 3 and convert it by expansion into mechanical energy by pushing on the movable partition 5. The energy is transmitted via the shaft 7. The cold chamber is filled with hot fluid. The hot fluid will release heat to the cold source 4 and convert its contraction into mechanical energy via the mobile partition 6 and transmit it via the shaft 8. The return to the initial step taking place at equilibrated pressure, the movement of the piston is achieved without effort.

Description

DESCRIPTION

TITLE: Thermodynamic engine

[Technical area]

The object of the present invention is a thermodynamic engine, which can be used for the conversion of heat or cold into mechanical energy.

The engine can be used, given its low temperature operation, for the recovery of fatal low temperature energies (with deviations of the order of a few tens of degrees).

We can consider its use for:

- improve the efficiency of thermal power plants by recovering the heat from cooling the power plants,

- improve the efficiency of heat engines by recovering the heat from the engine and / or the exhaust gases,

- recover the cooling heat from industrial processes,

- recover the cooling heat from the IT industry (servers, etc.).

The engine can be used for the production of mechanical energy and indirectly of electrical energy, from a heat source created for the occasion, for example by combustion of a fuel. Which makes it a high efficiency heat engine.

[State of the art]

Fossil energies (oil, gas, coal, nuclear ...) will be exhausted sooner or later. As of today, we must at least preserve these energies by optimizing their use, and at best find solutions to be able to do without them. The use of renewable energies seems to be an interesting path if one knows not to be dependent on an external factor (sun, wind, water, ...). In addition, fossil fuels are exhaustible, the energies resulting from the exploitation of hydrocarbons generate CO2-type emissions which contribute to the greenhouse effect and consequently to the climatic disturbance that we are experiencing.

Most thermodynamic engines operate by following well-known cycles, of which one can quote: the RANKINE cycle, the BRAYTON cycle, the cycle STIRLING, the CARNOT cycle.

For most of these cycles, there must be either large temperature differences, high operating pressures, or both. Engines using a RANKINE cycle are often reserved for high power installations. Even if the operation of these engines is well mastered, it can be complex in its implementation. The main shortcomings of engines using the RANKINE cycle are often the use of fluids under conditions of high pressure and temperature. The efficiency of these motors can be affected by the use of complex and energy-intensive auxiliary installations.

Some engines use the BRAYTON cycle, which characterizes piston combustion engines. The BRAYTON patent (US 125166) of 1872 describes an open combustion cycle for a piston engine. BRAYTON was not the first to look at this type of cycle. Before him BARBER, (patent UK1833) in 1791, SIEMENS (patent UK2074) in 1860 and ERICSSON (patent UK6409) in 1833, had worked on this type of engine.

An approach, more up to date, was carried out by the Reverend STIRLING (UK patent 4081) in 1816, with a valveless engine, of which there are several versions (alpha, beta, gamma, ..).

In theory, the efficiency of the STIRLING cycle is equivalent to the efficiency of a CARNOT cycle. In practice, the operation of STIRLING engines requires high pressure and heat. Their use is restricted to certain niche markets.

The efficiency of all the systems described above is greatly impacted by the need to use a compressor. The mechanical energy available at the outlet being equal to the energy produced by the expansion minus the energy required for compression

[Disclosure of the invention]

Our engine is characterized by the use of a fluid in a closed circuit, working between one (or more) hot room and one (or more) cold room. Each chamber is equipped with a movable partition connected to a mechanical system allowing the recovery of the mechanical energy produced.

Our engine is powered by a hot source and a cold source.

The purpose of the hot spring is to supply the hot chamber with calories through the wall of the purpose of the room and the cold source is to evacuate calories from the cold room through the wall of the room.

The cold fluid (from the cold room) is injected into the hot room. Under the effect of the temperature difference, the cold fluid captures calories and expands and / or increases in pressure. This variation is converted into mechanical energy by moving the movable partition. At the end of the cycle, the hot fluid is evacuated to allow the restart of a new cycle.

The hot fluid (from the hot room) is injected into the cold room. Under the effect of the temperature difference, the hot fluid releases calories and contracts and / or drops in pressure. This variation is converted into mechanical energy by the displacement of the movable partition. At the end of the cycle, the cold fluid is evacuated to allow the restart of a new cycle.

When the discharge and intake valves open, the pressures are balanced and allow the movable partition to move effortlessly (apart from the friction forces), for the launch of a new cycle.

[Description of the drawings]

FIG. 1 represents a possible embodiment with 2 combined cylinders and substantially identical chamber sections (not shown in the figure, the system for managing the movement of the cylinder and the distribution system). The hot chamber 1 is maintained at temperature by the hot source 3, provided here by the circulation of a heat transfer fluid. The wall of the chamber transmits heat from the hot source to the cold fluid. The movable partition 5 allows variations in volume during the filling, working and evacuation phase. The rod 7 transmits the forces and allows the movement of the partition 5 to be controlled. The valves 9 and 11 ensure the admission and discharge of the fluid. During the engine phase, the piston comes out under the effect of the increase in pressure in chamber 1.

The cold room 2 is maintained at temperature by the cold source 4, provided here by the circulation of a heat transfer fluid. The wall of the chamber transmits heat from the hot fluid to the cold source. The movable partition 6 allows variations in volume during the filling, working and evacuation phase. The rod 8 transmits the forces and allows the movement of the partition 6 to be controlled. The valves 10 and 12 ensure the admission and discharge of the fluid. During the engine phase, the piston comes out under the effect of the decrease in pressure in chamber 1. Figure 2 shows a hot room and a cold room operating in a differentiated manner. In this case, differentiated control systems will independently manage the movements of the hot and cold pistons.

FIG. 3 diagrammatically represents an assembly of several jacks allowing the complete production of an engine. The jacks are assembled in a star to ensure continuity of the forces transmitted, and on several levels to multiply the power produced. At the end is schematically shown an alternator 30 for use as an electric generator.

FIG. 4 represents the different operating steps of the thermodynamic engine, in the case of an installation with combined jacks. Step 0: Filling of the hot room (small emptying of the cold room); Step 1: Heat transfer from heat sources to hot and cold fluids; Step 2: Displacement of the piston under the effect of the increase in pressure in the hot chamber and the decrease in pressure in the cold chamber with recovery of mechanical energy;

Step 3: Opening the valves and emptying the cold room;

Step 4: Filling the cold room and emptying the hot room.

FIG. 5 represents the different possibilities of association of the jacks. The chambers can be made to work independently only in one direction (A). It is possible to combine hot and cold rooms (combined); the recovered work is carried out only in one direction (B). The pistons can be used in double effect, independently between the hot rooms and the cold rooms with work recovery in both directions (C). Double-acting jacks can be combined by combining the movements of the hot and cold rooms (D).

FIG. 6 represents a cam serving to manage the displacement of the piston of FIG.

1.

Figure 7 shows the operation of the engine.

[Detailed description]

Part (A) of FIG. 7 represents the displacement of the piston over a cycle (to be related to FIG. 1). The rise corresponds to the exit of the piston and the descent corresponds to the retraction of the piston.

Part (B) of figure 7 represents the temperature variations of the hot fluid in the cold room (decreasing curve), as well as the temperature of the cold fluid in the hot room (increasing curve).

Part (C) of FIG. 7 represents the pressure variations in the hot chamber (top curve) and in the cold room (bottom curve).

At point (a), the piston is fully extended, it is at bottom dead center. At point (b), the piston is retracted to the maximum, it is at top dead center. The driving phase of the piston is between points (d) and (a).

The rise: filling the cold room and emptying the hot room.

The valves are open and the pressure in the chambers is equal to the pressure PO (pressure outside the circuit). We can consider that if the movements are done fast enough, there is no heat exchange.

Descent: filling the hot room and evacuation of the overflow from the cold room (evacuation of the overflow from the cold room is not necessary if you are working with separate pistons). At the end of this phase, the intake valves are closed.

Then the piston stroke is blocked, the hot and cold chambers are closed. As illustrated in part (B) of FIG. 7, the cold fluid present in the hot chamber absorbs calories and heats up, which causes the chamber to rise in pressure (see part (C) of FIG. 7).

The hot fluid present in the cold room, for its part, gives up calories, which leads to a drop in the pressure in the cold room (see part (C) of figure 7).

A pressure difference was thus generated between the 2 chambers of the jack, and a heat variation was transformed into a pressure variation.

During the descent, with displacement of the piston under the effect of the pressure variation between the 2 chambers with energy recovery, before the end of this descent, the cold chamber discharge valve is opened and evacuation of the fluid from the cold room. At the lowest point of the descent, the hot chamber discharge valve opens.

As the operation of the motor is intermittent, it is possible to associate several jacks together or to use an inertia flywheel, to ensure the continuity of the movement.

The heat exchange and energy recovery phases can be separated. This is the case if an isochoric exchange followed by an adiabatic displacement is carried out in the chamber (more interesting in the case of work in the gas phase).

The speed of movement of the partition determines the type of transformation carried out. For example for an isochoric transformation, the speed of displacement of the partition is zero (transformation at constant volume).

It is also possible to have a heat exchange phase combined with the energy recovery phase, for example when we want to take advantage of a phase change, the heat exchange will accompany displacement under the effect of the phase change.

The thermodynamic engine takes the following form (see figure 1). It is shown here with a hot room and a cold room one behind the other (combined). The engine can be operated with on one side the hot chamber (s) and on the other side the cold chamber (s) and independent piloting and distribution systems. Likewise, the sections of the hot and cold rooms are not necessarily identical. This representation simplifies the understanding of the operation of the engine.

The hot chamber of the engine 1 is maintained at a substantially constant temperature by virtue of the hot source 3. The hot source can be produced by the circulation of a hot heat transfer fluid, by combustion, by a heat pump or any other means capable of to maintain a substantially constant temperature inside the hot chamber. The partition which separates the hot source from the hot chamber will preferably be made of a heat-conducting material of the copper, bronze, brass or aluminum type, in order to optimize the energy transfers. In the event of high temperature, it will be possible to replace these materials with materials with better temperature resistance (such as steel, for example), this will however reduce the efficiency of the system.

The hot source can, for example, be supplied by the recovery of fatal energy or by a heat pump, or the combustion of a fuel.

The hot chamber is closed by a watertight movable partition 5. An axis 7 linked to this partition makes it possible to manage the phases of displacement of the partition and to recover the energy of the expansion of the fluid via a system of the cam, eccentric or other type. . The hot (empty) chamber, piston at top dead center, is filled with cold fluid (in liquid form, wet vapor, or gas) by the inlet valve 9 by lowering the piston or by injection.

The cold fluid captures the heat from the hot source 3 through the partition of the hot chamber 1, which causes the fluid to heat up, possibly a phase change.

The movement of the movable partition will be controlled to optimize the recovery of the heat received and the power transmitted. The movement of the mobile wall under pressure makes it possible to recover the energy linked to the expansion of the fluid.

At the end of the heating / expansion cycle, the exhaust valve 11 opens, there is a balance of pressures. The piston can descend to its bottom dead center (if it is not already there) and go up to its top dead center, exhaust valve 11 open. The cycle resumes from its initial phase.

The distribution is a function of the temperatures of the hot and cold sources, ideally the distribution will be adapted to the temperatures of the hot and cold sources, if these temperatures vary.

The cold room 2 is kept at temperature thanks to the cold source 4. The cold room is closed by a watertight mobile partition 6. An axis 8 linked to this partition makes it possible to manage the phases of movement of the partition and to recover energy of the contraction of the fluid via a system of the cam, eccentric or other type. The partition which separates the cold source from the cold room will preferably be made of a heat-conducting material of the copper, bronze, brass or aluminum type in order to optimize the energy transfers. In the event of high temperature, it will be possible to replace these materials with materials with better temperature resistance (such as steel, for example), this will however reduce the efficiency of the system.

The cold room (empty) is filled with hot fluid (in vapor or gas form) by the inlet valve 10 or by injection. The cold room is empty when the piston is at bottom dead center.

In the case of an engine with separate cylinders, filling is effective when the piston has reached top dead center. In the case of an engine with combined cylinders, as in our figure, filling is effective when the piston is lowered according to the filling of the hot chamber.

The hot fluid releases heat to the cold source 4 through the partition of the cold room 2, which causes the fluid to contract, possibly a phase change. The movement of the movable partition will be controlled to optimize the release of heat to the cold source and the transmitted power.

At the end of the cooling cycle, the exhaust valve 12 opens and there balances the pressures.

The cooling of the cold room is provided by the passage of a heat transfer fluid. The distribution is a function of the temperatures of the hot and cold sources, ideally the distribution will be adapted to the temperatures of the hot and cold sources, if these temperatures vary.

A buffer zone will eventually make it possible to take into account variations in volumes during the exchange phases.

First observation: Fluid exchanges between the jacks are done at equal pressure. This means that this type of engine works without having to provide conventional mechanical compression.

Second observation: The compressed fluid provides a driving force on the piston, just as the contracted fluid provides a driving force on the piston.

The efficiency of our engine, combining an engine contraction with an engine expansion allows very good outputs to be obtained.

With engines with conventional thermodynamic compression (on a Rankine cycle for example), the first principle of thermodynamics makes it possible to write:

Qch + Wcomp = Qfr + Wdet with

Qch = the heat supplied for the hot source

Wcomp = the work provided to achieve the compression

Qfr = the heat released by the cold source (cooling)

Wdet = the work produced by the expansion The motor efficiency is therefore: h = (Wdet - Wcomp) / Qch

Knowing that the recoverable work of the system is equal to:

Wutil = Wdet -Wcomp

With our engine we can write:

Qch = Wcont + W det + Qfr with

Qch = the heat supplied by the hot source

Wcont = the work produced in the cold room by the contraction of the fluid Wdet = the work produced in the hot room by the expansion of the fluid Qfr = the heat released by the cold source The efficiency of our motor is therefore: h = (Wdet + Wcont) / Qch

Knowing that the recoverable work of our engine is equal to:

Wutil = Wcont + Wdet

This will result in a significant improvement in engine efficiency and an equally significant drop in the cooling requirement.

The shape, the thickness of the envelope, the choice of material determines the heat transfer capacity between the chamber and the source. This capacity is expressed in Watt / K and also determines the transmissible power per degree of deviation, and consequently the recoverable motor power.

For example, a 40mm diameter copper cylinder, imm thick and 100mm long, can transmit a power of 4000W / K over its total length.

The shorter the filling time, the less time the fluid will have to exchange heat with the wall of the chamber during the filling phase. A return spring can be added (not shown in the drawing) on the jack in order to reduce the time and the return forces of the jack (filling the cold room and emptying the hot room).

The management of the displacement will determine how the fluid is transformed. The management of the displacement of the piston can be done as in Figure 2 by a cam 13,14, or by any other means of eccentric type, crank, ...

Blocking the piston 5 makes it possible to obtain isochoric heating of the fluid, which may be of interest in the case where the fluid is a gas. At the end of the transformations in each of the chambers, we will ideally arrange for the pressure of the hot and cold fluids to approach the intermediate pressure (PI). In this way, there will be no pressure relief when opening the valves.

In the case where the fluid remains in the gaseous phase, the higher the pressure PI will be, the higher the energy density of the gas will also be.

In the event that the fluid is used with a phase change, the fluid (in liquid form) will heat up. This heating will cause the hot chamber 1 to rise in pressure. The greater the warming, the higher the pressure. The movement of the piston will convert the liquid fluid into vapor. At the end of the first phase, the discharge valve is open, the pressure equilibrium is achieved between the interior of the hot chamber and the transfer circuit at pressure PI.

If PROPANE is used, a temperature difference of 30K will make it possible to obtain a pressure difference of the order of 8 bars between the 2 chambers (this pressure is the usual pressure of a pneumatic network) however the intermediate pressure PI will be around a dozen bars.

In the case of using BUTANE, a temperature difference of 30K will make it possible to obtain a pressure difference of the order of 3 bars between the 2 chambers (lower pressure difference than with the use of PROPANE but sufficient to achieve the displacement of the movable partition).

The motor can be sized to work with a gaseous phase fluid, with a phase change, with a dry steam / wet steam cycle or combinations of these cycles.

Referring to Figures 6 and 7, consider the example of the use of a gas considered perfect. The cold source is at 0 ° C, and the hot source is at 100 ° C. For this example, we also consider that all the transformations are perfect and that there is a perfect temperature equilibrium at the end of each heating and cooling phase.

The jack, such as that shown in Figure 1 or 2, is therefore controlled by the intermediary of the cam, such as that shown in Figure 6.

Point (b) is the point at which the cylinder is at its top dead center, i.e. hot chamber 1 is empty, and cold chamber 2 is full beyond its filling volume optimum.

At this point (b), the inlet valve 10 of the cold room 2 is open. This is when the inlet valve 9 of hot chamber 1 opens.

Going from point (b) to point (c), the rotation of the cam allows the hot chamber

1 to fill up, and at the same time reduces the volume of the cold room 2. At point (c), the inlet valves 9 and 10 are closed, and the respective volumes of the hot rooms

2 and cold 1 are hermetically sealed.

The cold gas, at the initial pressure of 20 bars, introduced into the hot chamber, will absorb heat from the hot source and will pass isochorically from the temperature of 0 ° C to the temperature of 100 ° C. Its pressure will therefore increase and go from 20 bars to approximately 27.3 bars, which corresponds to the pressure of the fluid heated in the hot chamber at point (d).

At the same time, the hot gas, still at the initial pressure of 20 bars, introduced into the cold room, will cool on contact with the cold source and will pass isochorically from the temperature of 100 ° C to the temperature of 0 ° C. Its pressure will therefore drop from 20 bars to approximately 14.6 bars, which corresponds to the pressure of the fluid cooled in the cold room at point (d).

Without a pressure difference when the hot and cold gases are introduced, by heating the cold gas and cooling the hot gas, a pressure difference is created between the two chambers. This pressure difference, of around 12.7 bars in our example, will allow the piston to move. At point (d), the piston will be able to move, release the stored energy and drive the cam in rotation. For a piston with a circular section of 40 mm in diameter, the thrust exerted is of the order of 160 daN.

At point (e), the pressure in the cold room is equal to the initial pressure. The discharge valve 12 opens. On returning to point (a), the bottom dead center of the cylinder is reached. The cold room is then completely emptied and the hot room drain valve 11 opens at the same time as the cold room drain valve 12 closes and the cold room inlet valve 10 closes. 'opens.

Returning from point (a) to point (b) then allows cold room 2 to be filled and hot room 1 to be emptied.

Claims

1. Thermodynamic engine using a fluid which works in a closed cycle between a hot chamber (1) where it receives heat and a cold chamber (2), where it releases heat, and where, at the same time as the fluid exchanges heat, it produces energy, the passage of the fluid from one chamber to another taking place at the same or almost identical pressure, which means that the exchange of fluid, between chambers, is almost effortless , the hot chamber (1) being equipped with a movable and sealed partition (5), with a rod for managing movements and transmission of forces via a cam (13) or an equivalent system, with intake valves ( 9) and discharge (11) controlled as required, the chamber being kept at temperature by the presence of a hot source (3) which supplies heat, the cold chamber (2) being equipped with a movable partition and sealed (6), a displacement management rod and transmission of forces via a cam (14) or equivalent system nt, intake 10 and delivery 12 valves controlled as needed, the chamber being kept at temperature by the presence of a cold source 4 which absorbs heat.

2. Thermodynamic engine according to claim 1, characterized in that it comprises a tubular hot source chamber (3), the supply of the hot source being located at one end of the tubular chamber, the return of the hot source is located at the opposite end of the tubular chamber

3. Thermodynamic engine according to any one of the preceding claims, characterized in that it comprises a tubular cold source chamber 4, the supply of the cold source being located at one end of the tubular chamber, the return of the cold source. cold source located at the opposite end of the tubular chamber.

4. A method of generating motion of a thermodynamic engine according to any one of the preceding claims, characterized in that it comprises the following steps:

• The cold fluid is injected into the hot chamber (1) by the hot chamber inlet valve (9), capturing the heat from the hot source, • The fluid transmits energy by moving the mobile hot chamber partition (5), controlled via the hot chamber rod 7 which also makes it possible to manage the rise and fall in pressure in the hot chamber (1).

• Once all the energy of the fluid is transmitted to the external system via the hot chamber rod 7, the fluid is discharged through the hot chamber discharge valve (11).

5. Method for generating movement of a thermodynamic engine according to any one of claims 1 to 3 or method for generating movement according to the preceding claim characterized in that it relates to the following steps

• The hot fluid is injected into the cold room (2) by the cold room inlet valve 10, releasing heat at the cold source,

• The fluid transmits energy by moving the movable partition (6), controlled via the cold chamber rod 8 which also makes it possible to manage the rise and fall in pressure in the cold chamber (2).

• Once all the energy of the fluid is transmitted to the external system via the cold room rod 8, the fluid is discharged through the cold room discharge valve 12.