FR3067439A1 - DERIVATION VALVE FOR RELAXATION MACHINE - Google Patents

Abstract

The present invention relates to a bypass valve (2) for regulating the flow of a fluid through a bypass channel (15) in parallel with the expansion zone (14) of an expansion machine (1) of a control system. waste heat recovery comprising: - a valve body (22) - a shutter (21) - and an actuator (23) fixed on said valve body (22) configured to actuate said shutter (21). Said valve is a two-way valve and said shutter (21) controls the flow rate of fluid flowing in said bypass channel (15).

Description

BYPASS VALVE FOR RELAXATION MACHINE

Field of the invention

The present invention relates to the field of expansion machines for recovering thermal energy from hot fluid, for transformation into mechanical or electrical energy, and more particularly bypass valves for expansion machine.

More specifically, the invention relates to an expansion bypass valve for a system for recovering thermal energy from an engine such as an internal combustion engine, and finds a particular application in the field of transport.

The general principle of such expansion machines is known in the prior art.

In particular, European patent application EP3128137 describes an assembly for controlling a flow of working fluid in the gaseous phase between its source and the intake of an expansion machine.

The purpose of this solution of the prior art is to avoid the penetration of the working fluid in liquid form into the machine, by reducing the pressure when the temperature of the fluid supplying the machine is too low. Another aim is to limit the pressure when it is excessive. For this, this solution provides a slide valve comprising several passages supplying on one side the inlet of the expansion machine, on the other side a bypass channel of the expansion machine opening into the exhaust zone of the relaxation machine.

Also known in the prior art is the international patent application WO 2015176142 vapor expansion device, said device comprising an expansion machine having an intake which is connected to an intake pipe and an exhaust which is connected to a delivery pipe. evacuation, the inlet pipe being provided with an inlet valve and the outlet pipe being provided with an outlet valve making it possible to isolate the space between the valves by closing these valves when the regulator n is not in operation, the device being provided with a steam supply which conditions the space between the valves when the expansion machine is not in operation, so that air cannot enter space.

In this document of the prior art, a referenced supply valve is connected to a controller which controls the opening when the expansion machine is put out of service and its closing when the expansion machine is put back into operation. This supply valve is placed on the steam supply circuit and not in the expansion machine.

The valve object of the invention makes it possible to ensure an optimal temperature rise of all the parts of the thermal machine, in particular during the start-up phase and to simplify the heating circuit, which makes it possible to reduce its bulk. .

It makes it possible to improve the operation of the machine in atypical operating regimes of the expansion machine by one and the same means constituted by this valve actuating a shutter disposed in the machine. The atypical functions presented in the invention are the following:

a) machine temperature too low,

b) overpressure on admission,

c) request to stop the machine,

d) overheating too low on intake and

e) overheating too weak at the exhaust.

State of the art

Patent application WO2017144857 discloses in the state of the art a 3-way bypass valve for regulating a flow of a fluid in a waste heat recovery system, the bypass valve comprising: a valve body; an inlet port defined inside the valve body, the inlet port being configured for fluid communication with an outlet of one or more evaporators of a waste heat recovery system; a first outlet port defined inside the valve body, the first outlet port being configured for fluid communication with an expansion machine of a waste heat recovery system; a second outlet port defined within the valve body, the second outlet port being configured for fluid communication with a condenser of a waste heat recovery system; a valve configured to prevent flow of fluid from the inlet port to the first outlet port; and an actuator configured to actuate the valve, characterized in that the bypass valve further includes a purge flow path providing fluid communication between the inlet port and the first outlet port, bypassing the valve .

We also know the US patent application US20150330530 describing a 3-way bypass valve for regulating the flow of a fluid in a waste heat recovery system which comprises a valve body, a valve coupled to the valve body and adapted to prevent the flow of fluid to an expansion machine, and a rod with at least one portion disposed in the valve body in which the rod is adapted to move the valve to allow the fluid to flow to the machine expansion valve and regulate the flow of fluid.

Patent application WO2017144860 describes another example of a dispensing valve. The dispensing valve comprises a body, a cylindrical drawer and a solenoid assembly, the body and the solenoid together defining a cavity, the body defining an inlet orifice, the cylindrical drawer being permanently mounted in said cavity, the cylindrical drawer defining a first outlet port and a second outlet port, and the distributor valve further comprising a ring, the ring being slidably mounted around the cylindrical slide in said cavity, and said ring being configured for actuation by the solenoid assembly to open and closing said first and second outlet ports to control the flow of fluid through the dispensing valve.

Disadvantages of the prior art

The solutions of the prior art relate to independent, massive valves which require bulky hydraulic connections with the expansion machine, sources of leaks.

The drawbacks of the solutions of the prior art relate in particular to the heat transfer between the high temperature zone, of active valve, subject to up to 250 ° C for machines using ethanol or cyclopentane as working fluid and l pneumatic or electromagnetic valve actuator. The high heat transmission to this actuator causes malfunctions related to the expansion of the components, components, the temperature resistance of some, in particular the elastomers for a pneumatic actuator, or the insulating varnishes and resins for an electromagnetic actuator.

This problem is aggravated for very compact machines, where the valve is partly housed in the cylinder head, and where one seeks to miniaturize the valve and especially its actuator which no longer has sufficient external surface to ensure its cooling.

Another problem is that of the high temperature seals of the valve components. To ensure perfect sealing, the solutions of the prior art plan to weld the components together, which makes the assembly irreversible and poses welding problems when these are made of different metals. For example, in the case of a compact valve integrated in the expansion machine, the stainless steel of the valve components and the cast iron of the expansion machine do not easily weld.

The solutions of the prior art do not allow the active area and the actuator to be thermally insulated sufficiently to allow satisfactory operation, or to ensure satisfactory sealing at high temperature.

Solution provided by the invention

The invention relates to a valve for controlling the opening or closing of the passage of the working fluid coming from the intake chamber, in a bypass circuit. In nominal operation, the valve is in the closed position, all the working fluid coming from the intake chamber then supplying the expansion zone delimited by the screw or the spiral.

The valve according to the invention has two particular characteristics: it is a two-way valve and not a three-way valve.

This valve is configured to be positioned inside the expansion machine, on an internal outlet of the high-pressure intake zone.

It can be positioned in the cylinder head cover or at the interface between the high-pressure intake chamber and the preheating means connected to the exhaust zone.

This configuration makes it possible in all circumstances to ensure a sweeping of the high-pressure intake zone by the working fluid, both when the valve is in the open position and when it is in the closed position, unlike the solutions of the prior art where this high-pressure inlet zone is scanned by the working fluid only when the valve is in the nominal operating position.

The valve according to the invention has two positions:

a) a closed position, corresponding to the nominal operation of the expansion machine, where the working fluid circulates inside the expansion machine from the intake zone to the exhaust passing through the expansion

b) an open position, corresponding to the aforementioned atypical situations, where the working fluid first passes through the intake chamber, to then open:

in a bypass circuit comprising the preheating means and which connects the intake zone and the exhaust zone without passing through the expansion zone, in the start-up phase where the machine is stopped and not running not

- in the expansion zone opening into the exhaust zone and into the bypass circuit, in the two other situations, where the machine is in operation.

Detailed description of a nonlimiting example of the invention

The present invention will be better understood on reading the detailed description of a nonlimiting example of the invention which follows, referring to the accompanying drawings in which:

- Figure 1 shows Rankine cycle according to the invention. a schematic view a - Figure 2 shows a diagram of 1 'invention. - Figure 3 shows variant of the invention. a view in chopped off a - Figure 4 shows second variant of the invention. a view in chopped off a - Figure 5 shows third variant of the invention. a view in chopped off a - Figure 6 shows fourth variant of the invention. a view in chopped off a - Figure 7 shows fifth variant of the invention. a view in chopped off a

General principle of a Rankine cycle

FIG. 1 represents a schematic view of a Rankine cycle according to the invention.

A Rankine cycle recovers waste heat from an associated rotary machine (801), which can be an internal combustion engine. This heat can be recovered in several places: on the cooling circuit, on the cooling of the compressed air upstream of the engine, on the cooling of the exhaust gases recirculated in the rotary machine or on exhaust gases (802 ) as shown in Figure 1.

In the latter case, a heat exchanger or evaporator (807) is inserted in bypass on the exhaust line after the pollution control system (803). A bypass valve (827) distributes the flows proportionally between said evaporator (807) and the normal exhaust.

The evaporator (807) is intended to evaporate the working fluid (808) of the Rankine cycle. The working fluid (808) is sucked in by the motor-pump unit (806) from the condenser (805), at a pressure defined by the expansion tank (828), the pressure of which is controlled by an electric valve controlled by pulses (829). Said valve (829) regulates the air pressure in the expansion tank (828) either by temporarily connecting the expansion tank (828) to a source of compressed air (821) or by connecting the expansion (828) to the atmosphere temporarily, either by closing the inlet to the expansion tank.

The temperature and pressure of the working fluid (808) upstream of the motor-pump unit (806) as well as downstream of the evaporator (807) are measured by sensors. The Rankine cycle computer receives these signals to control the actuators of the system as well as a vapor temperature in the expansion machine (1) measured either in the expansion zone (14) or in the exhaust zone ( 13).

The steam produced in the evaporator (807) flows to the expansion machine (1). The expansion machine (1) comprises three zones: an inlet zone (11) for the high pressure steam which is connected to the expansion zone (14), itself connected to the exhaust zone (13 ) at low pressure. The bypass valve (2) opens and closes a bypass channel (15) connecting the intake zone (11) and the exhaust zone (13). The bypass valve (2) is advantageously pneumatic and is connected to the source of compressed air (821). An electric valve (820) controls the admission of air into the bypass valve (2) either by connecting the bypass valve to the source of compressed air (821), or by connecting the bypass valve (2) to the atmosphere. The bypass channel or the bypass valve (2) further comprises a restriction, typically of the order of 20 mm 2 in order to limit the volume flow through the bypass channel and cause a pressure rise in the zone upstream of the restriction.

Low pressure steam escaping from the expansion machine (1) from the exhaust zone (13) flows through the condenser (805) in order to return to the liquid state. The condenser (805) is cooled either by a fluid from the associated rotary machine (801) or by ambient air. For example, one or more of the cooling circuits of the associated rotary machine (801) can be used. The condensed working fluid is then re-admitted by the motor-pump unit (806), either to continue to circulate, or to return to the expansion tank (828).

The expansion machine (1) is connected to a rotary shaft (813) of the associated rotary machine (801) via a reduction gear (810).

General architecture of the valve according to the invention

Figure 2 shows a schematic view of the valve according to the invention.

The expansion machine (1) has an intake port (10) opening into an intake zone (11) and an exhaust port (12) opening into an exhaust zone (13). The working fluid (808) in gaseous form circulates from the intake port (10) to the exhaust port (12). It is admitted into the intake zone (11), then into the expansion zone (14) and finally into the exhaust zone (13). According to several operating modes, the working fluid preferentially circulates through a bypass channel (15) bypassing the expansion zone (14). The opening of this channel is controlled by the bypass valve (2) which is housed in the expansion machine (1). This consists of a shutter (21) sliding in a valve body (22). The shutter is actuated by the actuator (23) which connected to an energy supply (24). In the case of an energy actuator is compressed air (821), (23) pneumatic, this typically within 7 of an actuator (23) is electricity, relative bars, electromagnetic,

In the case this energy typically 12, 24 or 48 direct volts.

This bypass valve (2) is a two-way valve, i.e. it has an inlet and an outlet only for the fluid, as opposed to a three-way valve which can have two outlets or two inlets .

In the remainder of the patent, the following terms will be used:

- bypass channel (15): conduit for the working fluid (808) putting a high pressure zone into communication with a low pressure zone, allowing circulation of the fluid from one or more evaporators of a Rankine circuit to a or several condensers in parallel with the expansion zone (14) of the expansion machine (1). In particular, the bypass channel (15) opens from an intake zone (11) of the expansion machine (1) and opens into the exhaust zone (13) of the expansion machine (1). This bypass channel (15) can be outside the expansion machine (1) or integrated inside the expansion machine (1).

reception area (100): These are means fitted in a room to receive and fix the bypass valve (2). The bypass channel (15) crosses this reception zone (100). Other functions can be added to the reception area (100) for example: shutter guide (21), seat (252) cooperating with the shutter, lip seal grooves, flat or O-ring seal, etc. . This reception area (100) can be arranged in the expansion machine (1) or in a room independent of it.

Detailed architecture of the valve according to the invention

Figure 3 shows a sectional view of a first variant of the valve according to the invention.

The valve (2) is housed in a reception zone (100), for example in the expansion machine (1). This reception zone (100) is a cylindrical machining, possibly tapped and bored. This reception area (100) opens into the bypass channel (15). An inlet orifice (1100) is arranged opening out into the bypass channel on the side of the advantageously this inlet orifice is drilled axially along the axis of the reception zone (100). An outlet orifice (1500) is arranged opening into the bypass channel on the side of the exhaust zone (13), advantageously this is drilled radially, perpendicular to the axis of the reception zone (100).

The shutter (21) is advantageously composed in this variant of two parts: a control rod (250) and a ball (251). The ball (251) is free, that is to say that it is not fixed to the control rod (250). The ball (251) can alternatively be welded to the control rod (250). It can thus be positioned at best on the seat (252) in order to guarantee the best possible seal. The control rod (250) present at its end on the side of the ball is a conical seat (253) in hollow intended to help zone of admission the ball to center on the seat: 252:

The half angle at the top of the seat cone (252) is typically of the order of

15 ‘to guarantee the best seal and avoid jamming. The half-angle at the top of the cone of the control rod (250) is typically of the order of 45

The valve body (22) is made up of two parts: the seat holder (220) and the guide (221). The seat carrier (220) is screwed into the expansion machine (1). The seat carrier is formed of a tubular conduit and a shoulder (228). The tubular conduit is pierced axially at its center, to define an inlet port (110) as well as radially above the seat (252) to define an outlet port (150) to form a conduit for the working fluid (808). A conical seat (252) is machined at the inner end of the tubular conduit to accommodate the ball (251) of the shutter (21). The guide (221) has a bore (222) for guiding the control rod (250) of the shutter (21).

Alternatively, on the variant shown in Figure 5, the guide (221) is directly screwed into the expansion machine (1). In this variant, the seat holder (220) is eliminated. In this case, the seat (252) is machined directly at the end of the reception area (100) in the expansion machine (1). The seals are modified: the shutter (21) comes directly to seal on the expansion machine (1) delimiting the intake zone (11) and the bypass channel (15). The seal between the guide (221) and the expansion machine (1) is produced by a seal (226) which can be a flat seal made of expanded polytetrafluoroethylene (PTFE) whose thickness is between 1 and 4 millimeters or a O-ring in FFPM or FPM (according to the nomenclature of standard ISO 1629: 1995) if the temperatures of the expansion machine (1) allow it.

Alternatively in the variant of FIG. 7, the shutter (23) can be guided directly on the walls (2211) of the reception zone (100) and no longer on the valve body (22) which is not used then more than fixing the actuator (23). The seat (252) receiving the shutter (21) is also machined directly in the reception area (100). The valve body (22) is only used to secure the actuator (23). The valve body (22) has a flange (2212) for attachment to the receiving area (100).

Either the area of the inlet (110) in the seat carrier (220) or the area of the inlet (1100) of the receiving area (100) is chosen to ensure loss of sufficient load when the valve is open for a given working fluid flow, so that the starting pressure of the expansion machine (1) is sufficiently high, typically of the order of 5 bars for a starting flow of the order of 10 g / s of ethanol. Considering the density of the working fluid in the superheated vapor phase, this gives a surface area of the typical orifice of approximately 20 mm 2.

The seal between the control rod and the guide (221) is ensured by a lip seal (223). The seal between the expansion machine (1) and the seat holder (220) is ensured by a flat seal (224) located on a frontal surface at the lower end of the seat holder (220) as well as by a seal. flat (225) located on the underside (229) of the shoulder (228) of the guide (221). The first flat seal (224) seals between a high pressure intake zone (11) and the bypass channel (15) opening into the low pressure exhaust zone (13). The second flat seal (225) seals between the bypass channel (15) and the exterior of the expansion machine (1). The seal between the seat carrier (220) and the guide (221) is also ensured by a seal (226).

This set of lip seals (223) and seals (224, 225 and 226) are located in the immediate vicinity of the high pressure intake zone (11) of the expansion machine (1). The working fluid (808) in this area is very hot. For a Rankine cycle using ethanol or cyclopentane the inlet temperature of the working fluid (808) can reach 250 ° C. The pressure is also important, up to 50 bars. These temperature and pressure, as well as the chemical compatibility with ethanol or cyclopentane under these conditions mean that few materials can be used to make these joints. The lip seal (223) is made of PTFE loaded with graphite, it also has a metal frame. The seals (224, 225 and 226) are preferably flat seals made of expanded PTFE with a thickness between 1 and 4 millimeters and a compressibility between 10 and 70%. These simultaneous seals on joint planes of different heights are allowed thanks to the compressibility properties of expanded polytetrafluoroethylene as well as the judicious choice of the thickness of the flat joints. The mechanical stop of the valve body (22) on the receiving zone (100) during screwing can be done on the lower part (229) of the shoulder (228) or else on a frontal surface at the lower end of the seat carrier (220).

Alternatively, the seals (224, 225 and 226) can be O-rings made of FFPM (224, 225) or FPM (225, 226) as shown in FIG. 6.

Alternatively, on the variant presented in FIG. 7, only the lip seal (223) is renewed, the other seals (224, 225 and 226) becoming useless.

The actuator (23) is fixed on the guide (221). The actuator shown is a pneumatic actuator comprising an elastomeric membrane (230), for example made of FPM, reinforced with a textile, and a cover (231) fixed on the guide (221). The membrane and the cover (231) define a pneumatic chamber supplied with compressed air by the connector (232) screwed into the cover (231). The membrane (230) is disc-shaped. It is pressed by a spring (233) in its center on the control rod (250). A cup (255) is disposed between the membrane (230) and the control rod (250) to avoid puncturing of the membrane (230). When a control valve supplies the chamber with compressed air, the membrane (250) pushes the shutter (21) on the seat (252) which then closes the passage of the working fluid (808) through the seat holder ( 220). The surface area of the diaphragm is calculated so that the available compressed air pressure makes it possible to close the shutter when the pressure in the intake zone is at its maximum admissible value.

The elastomer membrane (230) and the cup (255) do not withstand high temperatures, typically below 160 ° C continuously. It is therefore necessary to reduce the heat flow from both the guide (221) and the control rod (250) as well as to dissipate the residual heat from the actuator (23). To do this, openings (227) have been arranged in the guide (221) intended to reduce conduction through the metal by reducing the conduction section. In addition, cooling fins (254) have been hollowed out in the control rod (250). These reduce the conduction section and increase the heat flow transmitted outside the system.

In addition, part of the control rod (250) or the cup (255) can be made of plastic in order to benefit from lower thermal conduction coefficients than those of metals.

Furthermore, according to a variant, the shutter (21) is hollow, pierced axially in its center from its upper face in a non-opening manner, in order to reduce the surface of thermal conduction as shown in FIG. 7.

Finally, cooling fins (234) can be fitted to the external surface of the actuator in order to increase the cooling surface of the latter and reduce its temperature. Alternatively, in Figure 4, a metal membrane (230) can be used. In this case, the guide (221) and the control rod (250) can be shortened. Only the plastic connector (232) can resist high temperatures.

According to a particular embodiment, the shutter (21) is not guided in translation by the valve body (22) but by walls (2211) of a receiving zone (100) of said valve. The shutter (21) cooperates with a seat (252) which is not machined in said valve body (22) but at the end of the reception zone (100).

Claims (19)

claims 1 - Bypass valve (2) for regulating the flow of a fluid (808) through a bypass channel (15) in parallel with the expansion zone (14) of an expansion machine (1 ) a waste heat recovery system comprising: - a valve body (22), - a shutter (21), - And an actuator (23) fixed on said valve body (22) configured to actuate said shutter (21), characterized in that - said valve is a two-way valve - said shutter (21) controls the flow of fluid (808) flowing in said bypass channel (15). 2 - Bypass valve according to claim 1 characterized in that said shutter (21) is composed of a control rod (250) and a ball (251). 3 - Bypass valve according to the preceding claim characterized in that said control rod (250) has a hollow conical seat (253) at its end on the side of said ball (251). 4 - Bypass valve according to claim 1 characterized in that said shutter (21) comprises a hollow element, having an axial bore not opening from its upper face. 5 - Bypass valve according to claim 1 characterized in that said actuator (23) is formed by a membrane (230) elastically deformable under the action of a fluid pressure, arranged transversely in the upper part of said valve , said membrane acting in axial support on said shutter (21). 6 - Bypass valve according to the preceding claim characterized in that said deformable membrane (230) is metallic. 7 - Bypass valve according to claim 5 characterized in that said deformable membrane (230) is made of elastomer. 8 - Bypass valve according to claim 1 characterized in that said actuator (23) is formed by an electric coil disposed in the upper part of the valve, said electric coil acting on a permanent magnet extending said shutter (21). 9 - Bypass valve according to claim 1 characterized in that said valve body (22) and said shutter (21) comprise thermal insulation and heat dissipation means disposed between the underside of said shutter (21) and said actuator (23). 10 - Bypass valve according to claim 9 characterized in that said upper end of said valve body has perforated walls (227). 11 - Bypass valve according to claim 9 characterized in that said shutter (21) has in its upper part of the fins (254) transverse thermal discharge. 12 - Bypass valve according to claim 9 characterized in that a part of said shutter (21) is made of thermal insulating material. 13 - Bypass valve according to claim 9 characterized in that said actuator (23) has cooling fins (234). 14 - Bypass valve according to claim 1 characterized in that the shutter (21) is guided in translation by the inner surface of the walls (2211) of a receiving area (100) of said valve. 15 - Bypass valve according to claim 1 characterized in that the shutter (21) has a shutter end protruding beyond the front end of the valve body and configured to adapt to the seat (252) of the shutter of the reception area (100). 16 - Bypass valve according to claim 1 characterized in that it comprises a lip seal (223) disposed around said shutter (21) in the upper part above an outlet orifice (1500) of said bypass channel (15) . 17 - Bypass valve according to the preceding claim characterized in that said lip seal (223) is a PTFE seal with a metal frame. 18 - Bypass valve according to claim 1 characterized in that said valve body (22) has a shoulder (228) which has at its lower surface (229) a groove receiving a flat seal in expanded PTFE, bearing against a second front surface of said receiving zone (100) of said valve. 19 - Bypass valve according to claim 1 5 characterized in that said valve body (22) has a seat holder (220) whose inlet orifice (110) is surrounded by a flat seal in expanded PTFE positioned at the front end of said seat carrier (220) and coming to bear against a front surface of the reception area (100) of said 10 valve.