WO2015193111A1

WO2015193111A1 - Working-fluid supply system and fuel cell arrangement and motor vehicle comprising the same

Info

Publication number: WO2015193111A1
Application number: PCT/EP2015/062429
Authority: WO
Inventors: Johannes Müller
Original assignee: Volkswagen Ag
Priority date: 2014-06-19
Filing date: 2015-06-03
Publication date: 2015-12-23
Also published as: DE102014211791A1

Abstract

The invention relates to a working-fluid supply system (200) for a fuel cell (10) or an internal combustion engine comprising – a fuel supply system (20) for supplying the fuel cell (10) or the internal combustion engine with a gaseous fuel, comprising a fuel pressure accumulator (22) for storing the fuel, a fuel supply path (21) which connects the fuel pressure accumulator (22) to the fuel cell (10) or the internal combustion engine, and an expansion machine (23) arranged in the fuel supply path (21) for expanding the fuel, and - an air supply system (30) for supplying the fuel cell (10) or the internal combustion engine with air, comprising an air supply path (31), a compressor (32) arranged in the air supply path (31) for compressing the air, and a pressure accumulator (33) arranged between the compressor (32) and the fuel cell (10), wherein the expansion machine (23) arranged in the fuel supply path (21) is connected in a force transmitting way to the compressor (32) arranged in the air supply path (31) for driving the compressor.

Description

description

Equipment supply system and fuel cell assembly and motor vehicle with such

The invention relates to a resource supply system for supplying a fuel cell or an internal combustion engine with a gaseous fuel, in particular hydrogen, and with air. The invention further relates to a fuel cell assembly having such a resource supply system and a motor vehicle having such.

Fuel cells are operated with a gaseous fuel, mostly hydrogen, which is electrochemically reacted with an oxidant, typically oxygen, to produce electrical energy. The hydrogen is in a corresponding

Stored hydrogen storage, which is connected via a supply path to the fuel cell. In particular, in mobile applications, the hydrogen is usually carried in high-pressure storage, in which the hydrogen is present, for example, at a pressure of 700 bar at maximum load. To supply the fuel cell, in known applications, the hydrogen is first decompressed by a throttle valve to a low pre-pressure, before a pressure control valve fine-tune to the desired

Operating pressure of the fuel cell makes. In current hydrogen vehicles, the energetic potential of high-pressure hydrogen is not used. The same applies to combustion engines that are operated with hydrogen as fuel.

DE 10 2010 035 860 A1 (US 2013/0157154 A1) describes a fuel cell arrangement with an H ₂ high-pressure accumulator which stores the hydrogen at a pressure of up to 700 bar, depending on the level. By means of a pressure regulator is initially a

Relaxation of the hydrogen to a pressure of 8 to 15 bar before it is fed to a arranged in the hydrogen supply line turbine. The turbine drives you

Compressor, which of the promotion of recirculated hydrogen in one

Recirculation line is used. In operating points where the pressure drop in the turbine is insufficient for a drive, a supporting drive is provided by an electric motor.

A very similar structure is described in DE 10 2006 003 799 A1, wherein here instead of the pressure regulator of the turbine a metering valve, for example in the form of a Laval nozzle, upstream of which almost all the pressure of the hydrogen storage is reduced before the hydrogen hits the turbine.

From DE 101 54 637 A1 is an arrangement of a fuel cell or a

Combustion engine with hydrogen known, which is upstream in a pressure accumulator. The pressurized hydrogen is decompressed via a turbine arranged in the hydrogen supply line before it is fed to the fuel cell or the internal combustion engine. The turbine is coupled to a compressor arranged in the air line and drives it for the supply of the fuel cell or the internal combustion engine with compressed air.

DE 10 2008 002 698 A1 describes a fuel cell arrangement in which a

A buffer for compressed air in the air line or in a side arm thereof is arranged between a compressor and the fuel cell input. In this case, the compressor is operated at idle or in low load phases of the fuel cell as a base load on and cached the compressed air. In addition, this document teaches to arrange a turbine in the cathode output line, which degrades the pressure difference between the operating pressure of the fuel cell to ambient pressure to produce mechanical or electrical energy.

The invention is an object of the invention to provide a resource supply system for supplying a fuel cell or an internal combustion engine with a gaseous fuel and with air, in which the energetic potential of the under

High-pressure stored fuel is used better.

This object is achieved by a resource supply system, a

Fuel cell arrangement and a motor vehicle with the features of the independent claims solved.

The fuel supply system according to the invention for supplying a fuel cell or an internal combustion engine with a gaseous fuel and with air comprises: a fuel supply system for supplying the fuel cell or the fuel cell

Internal combustion engine with a gaseous fuel, comprising a

Fuel pressure accumulator for storing the fuel, a

Fuel supply path which connects the fuel pressure accumulator to the fuel cell or the internal combustion engine, and arranged in the fuel supply path expansion machine for relaxing the fuel and an air supply system for supplying the fuel cell or the

An internal combustion engine with air, comprising an air supply path, one in the

Air supply path arranged compressor for compressing the air and arranged between the compressor and the fuel cell pressure accumulator.

In this case, the expansion machine arranged in the fuel supply path is connected in a force-transmitting manner to the compressor arranged in the air supply path for driving the same.

By using the expansion machine, which drives the compressor to compress the air to be supplied to the fuel cell or the internal combustion engine, part of the energy of the fuel, more precisely part of the enthalpy, is converted into kinetic energy and used for performing mechanical work. This work in turn is used in the system for compressing the supply air, which is conveyed into the accumulator and stored in this. From this pressure accumulator, the fuel cell or the

Internal combustion engine supplied. By utilizing the pressure energy of the fuel, the system efficiency is increased. Through the accumulator, the air operating pressure can be controlled or regulated independently of a current operating point-dependent fuel mass flow, whereby the compensation of load fluctuations is made possible. In particular, with rapid increases in load on the fuel cell or the internal combustion engine, the required operating pressure can be quickly represented by the pressure accumulator and thus the system can be operated more dynamically. The air mass flow is through

Caching in the pressure accumulator thus decoupled from the compressor operating point, so that when used to drive a motor vehicle, an increased driving performance is achieved by the power available independently of the compressor operating point.

In addition, the invention allows a reduction in fuel consumption. By the

The inertia of the compressor must be changed when the load point of the system changes

Namely, run up the compressor impeller, which can take up to about one second

During this time, the system can not provide increased power, the air path is the sluggish path at this point, and high drive power is required for a fast start-up, sometimes more than double the power required for steady-state operation This dynamic proportion of the compressor capacity is reduced by the invention, since the air reservoir is present in the pressure accumulator Since the fuel turbine power is usually smaller than the required compressor power, the compressor in the prior art must additionally be electrically operated be saved by the pressure accumulator part of the electrical energy and thus fuel. In a preferred embodiment, the air supply system further comprises a bypass line, which downstream of the compressor and upstream of the pressure accumulator of the

Air supply path branches off and downstream of the accumulator and upstream of the

Fuel cell or the internal combustion engine opens into the air supply path. The bypass line thus allows bypassing the pressure accumulator. Thus, for example, at low load operating points, the compressor may deliver the (correspondingly less compressed) air directly into the fuel cell or engine. Even in the case of a maximum filling state of the accumulator can be made use of the bypass line. Preferably, the air supply system has an actuating means which opens or closes the bypass line and thus allows control of the guided over the bypass line portion of the delivered air.

In an alternative embodiment, the air supply system further comprises a side arm branching off from the air supply path between the compressor and the fuel cell and connecting the air supply path to the pressure accumulator. Here, an adjusting means is preferably provided at the branch point of the side arm of the air supply path, for example, a 3-way valve which connects the pressure accumulator selectively with the fuel cell or the internal combustion engine or with the compressor or the compressor, bypassing the pressure accumulator directly to the fuel cell or the internal combustion engine connects.

According to an advantageous embodiment of the invention, the

Betriebsmittelsversorgungssystem on a separator, which allows a decoupling of the expansion machine and the compressor from each other. The separator may be, for example, a clutch or an idle circuit. This allows idling of the expansion machine without the compressor being driven by it. This is useful, for example, if the air pressure accumulator has a maximum fill level.

In a preferred embodiment of the invention, the compressor is exclusively by the

Expansionsmaschine driven, that is, there is no auxiliary drive component available. As a result, the system complexity and space requirements is minimized and an additional power requirement for the drive is avoided. Alternatively, however, a

Auxiliary drive component be provided for driving the air compressor, alone or driving the compressor together with the expansion machine. As an auxiliary drive component, for example, an electric motor can be used.

Furthermore, an advantage of the invention is the fact that due to the performance

mechanical work in the gas relaxation decreases the enthalpy of the gas, the

So relaxation is polytropic, whereby a cooling of the fuel takes place. This cooling energy can be used with advantage in various ways.

According to a preferred embodiment, the operating medium supply system is set up to pressurize the expansion machine with a fuel pressure of at least 20 bar, in particular of at least 50 bar, preferably of at least 200 bar (inlet pressure). It is particularly preferred to pressurize the expansion machine with the full, level-dependent fuel pressure of the fuel pressure accumulator. This is at current hydrogen tanks at about 700 bar, with higher pressures of 1000 bar or more are conceivable. Thus, there is preferably no pressure reduction or expansion of the fuel upstream of the expansion machine. Advantage of the highest possible input pressure to the expansion machine is that thus a particularly large mechanical power is generated by the expansion machine. The maximum output depends on the

Efficiency of the expansion machine from.

In a preferred embodiment of the invention, the expansion machine is designed to relax the fuel polytropically, ie with a decrease in enthalpy and increase in entropy and cooling of the fuel. The polytropic process allows the conversion of the enthalpy of the fuel into mechanical energy and the use of the cooled fuel for cooling.

The expansion machine preferably comprises all types of machines that allow polytropic expansion of gases. In particular, the expansion machine is a

Turbomachine, preferably a turbomachine (also called turboexpander or turbine), or a piston expansion machine.

It is further preferred that the expansion engine undertakes the expansion of the fuel over as great a pressure difference as possible, ie to an outlet pressure which is as close as possible to the desired value desired in the fuel cell or in the internal combustion engine (ie the operating pressure). The operating pressure of the fuel cell fuel is in a range of 1 to 12 bar, typically at 1, 5 to 3 bar. The operating pressure of Hydrogen combustion engines tend to be slightly higher. In particular, is the

Output pressure of the fuel downstream of the turbine at most 20 bar, preferably at most 10 bar, more preferably at most 5 bar, above the operating pressure of the fuel cell or the internal combustion engine. In other words, over the

Expander virtually all the pressure of the fuel pressure accumulator degraded. In this way, a particularly high amount of mechanical or electrical energy can be obtained and also a particularly strong cooling of the gas can be achieved. The pressure difference (Δρ) via the expansion machine is realized as large as possible.

Preferred pressure differences across the expansion machine are at least 100 bar, in particular at least 200 bar, or even at 400 bar or above. In a particularly preferred embodiment, the maximum pressure difference of 698.5 bar is used.

Preferably, the fuel is hydrogen. In the case of hydrogen, it is advantageous that this is usually present in high-pressure reservoirs, for example with a pressure of at least 200 bar, in particular at least 500 bar, preferably at least 700 bar (in each case at the maximum fill level of the reservoir). These high storage pressures allow a particularly effective use of the energy potential in the sense of

Invention.

The invention further relates to a fuel cell assembly comprising a fuel cell and a resource supply system for supplying the fuel cell with a gaseous fuel, in particular hydrogen, as well as with air according to the present invention.

Finally, the invention relates to a motor vehicle, a fuel cell or a gas-powered internal combustion engine and the inventive

Equipment supply system includes.

Further preferred embodiments of the invention will become apparent from the remaining, mentioned in the dependent claims characteristics.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

The invention is described below in embodiments with reference to the associated

Drawings explained. Show it: 1 shows schematically a fuel cell arrangement with a fuel cell and a resource supply system for supplying the fuel cell with hydrogen and air according to a first embodiment of the invention and

2 schematically shows a fuel cell arrangement with a fuel cell and a resource supply system for supplying the fuel cell with hydrogen and air according to a second embodiment of the invention.

FIG. 1 shows a fuel cell arrangement, designated as a whole by 100, of a motor vehicle, not shown here. The fuel cell assembly 100 comprises a fuel cell 10 and a resource supply system 200 according to the present invention, which supplies the fuel cell with the resources, here hydrogen as fuel and air as the oxidant.

The fuel cell 10 comprises an anode and a cathode, which by a

ion-conducting, in particular proton-conductive membrane are separated from each other (not shown in detail). Typically, fuel cells include a plurality of such single cells arranged in a fuel cell stack.

The fuel cell 10 has an anode inlet 1 1, via which a supply of the fuel, here hydrogen, takes place. Unreacted hydrogen is released via a

Anode outlet 12 discharged via an anode exhaust gas line 13. In addition, there may be a recirculation line, not shown here, which returns the unreacted hydrogen from the anode exhaust gas line 13. On the other hand, the cathode chambers of the fuel cell 10 are supplied with an oxidizing agent, in this case air, via a cathode inlet 14. The cathode exhaust gas and the water generated in the fuel cell reaction are removed via a cathode outlet 15 and a cathode exhaust gas line 16 connected thereto.

During operation of the fuel cell 10, the supplied hydrogen H _{2 is} oxidized to protons H ⁺ at the catalytic electrodes of the anodes with the release of electrons. At the same time ^"anions is reduced at the cathode catalytic electrode of the supplied oxygen 0 ₂ under recording of air supplied via an external circuit electrons to 0. ² which in turn react with the protons H ⁺ that via the proton-conducting membrane to the

Reach the cathode side, to water H ₂ 0. In this way, an electric current is generated, for example, used for an electric motor drive of a vehicle or can be cached in an energy storage.

The fuel cell assembly 100 has a total denoted by 200

Equipment supply system, which on the one hand, a fuel supply system 20 for supplying the fuel cell 10 with fuel (hydrogen) includes and a

Air supply system 30 for supplying the fuel cell 10 with air.

The fuel supply system 20 has a fuel supply path 21, which connects a fuel pressure accumulator 22 for storing the hydrogen with the anode inlet 11 of the fuel cell 10. The reservoir 22 is preferably a high-pressure fuel reservoir in which the hydrogen is stored under high pressure. For example, at maximum level of the accumulator 22, there is a fuel pressure of 700 bar or more.

The fuel supply system 20 further includes an expansion engine 23, which is disposed in the fuel supply path 21 and serves to relax the fuel. The expansion machine 23 is a turbomachine in the example shown here. During operation of the fuel cell assembly 100, hydrogen is supplied from the reservoir 22 to the turbomachine 23 via the fuel supply path 21. In this case, this is preferably applied to the unabated pressure of the memory 22, for example, with a pressure of 700 bar at maximum level of the memory. In the expansion machine 23, a polytropic relaxation of the hydrogen takes place to an outlet pressure, which depends on the efficiency of the expansion machine 23. For example, a relaxation takes place to an outlet pressure which is substantially at the operating pressure of the fuel cell 10 or slightly above it. In this way, virtually the entire differential pressure between storage pressure and operating pressure of the hydrogen over the

Expansionsmaschine 23 dismantled. Optionally, downstream of the expansion machine 23, a pressure, measuring and control device may also be arranged (not shown), which adjusts the hydrogen pressure from the outlet pressure of the expansion machine 23 to the operating pressure of the fuel cell 10.

The resource supply system 200 further includes the air supply system 30. This has an air supply path 31, which surrounds the environment with the

Cathode input 14 of the fuel cell 10 connects. In the air supply path 31, a compressor 32 is arranged, which a compression of the conveyed air to a pressure effected above the ambient pressure. The compressor 32 is force-transmitting connected to the expansion machine 23, for example via a shaft 24. In this way, the expansion machine 23 drives the compressor 32, so that it is possible to dispense with an otherwise driving source, for example an electric drive motor, for the compressor 32. The compressed air through the compressor 32 is conveyed into a pressure accumulator 33, which is arranged directly in the air supply path 31 in the example shown. As shown in FIG. 1, upstream and / or downstream of the pressure accumulator 33

Pressure control means 34, 35 may be arranged, which allow a control or regulation of the pressure and a barrier. For example, the pressure control devices 34, 35 are designed as controllable valves.

Further, a separator 25 is indicated in Figure 1, which interrupts the shaft 24 and thus allows decoupling of the expansion machine 23 and the compressor 32 from each other. The separator 25 may be formed, for example, as a clutch or in the form of an idle circuit. The separator 25 allows the operation of the

Expansion machine 23, even if a drive of the compressor 32 is not necessary or not desirable. This may be the case, for example, when the pressure accumulator 33 is filled to the maximum and can take over the sole supply of the fuel cell 10.

FIG. 2 shows a fuel cell arrangement 100 with an alternative embodiment of the operating medium supply system 200 according to the invention. In this case, matching elements are designated by the same reference symbols as in FIG. 1 and have the functionality already described. The embodiment shown in Figure 2 differs from that of Figure 1 in a bypass line 36 which branches off between the compressor 32 and the pressure accumulator 33 of the air supply path 31 and downstream of the pressure accumulator 33 and upstream of the fuel cell 10 opens again into the air supply path 31. The bypass line 36 has an adjusting means 37, for example a pressure regulating valve, which allows control or regulation of the portion of the conveyed air through the bypass line 36. The bypass line 36 allows a bypass of the pressure accumulator 33, for example, in operating situations when this has reached its maximum level.

Although the invention has been presented above in connection with the supply of fuel to a fuel cell, an application of the invention

Supply system also for gas-powered, especially hydrogen-powered

Internal combustion engines possible. LIST OF REFERENCE NUMBERS

A fuel cell assembly

fuel cell

anode input

anode output

Anode exhaust gas line

cathode input

cathode output

Cathode exhaust gas line

Working fluid supply system

Fuel supply system

Fuel supply path

High-pressure fuel reservoir

Expansion machine / turbo machine

wave

Separator / clutch

Air supply system

Air supply path

compressor

accumulator

Pressure control device

bypass line

actuating means

Claims

claims

1 . A fuel supply system (200) for a fuel cell (10) or a fuel cell

Internal combustion engine, comprising

- A fuel supply system (20) for supplying the fuel cell (10) or the internal combustion engine with a gaseous fuel, comprising a

Fuel pressure accumulator (22) for storing the fuel, a

Fuel supply path (21) which connects the fuel pressure accumulator (22) with the fuel cell (10) or the internal combustion engine, and one in the

Fuel supply path (21) arranged expansion machine (23) for

Relaxation of the fuel, as well

- An air supply system (30) for supplying the fuel cell (10) or the

An internal combustion engine with air, comprising an air supply path (31), a compressor (32) arranged in the air supply path (31) for compressing the air and an accumulator (33) arranged between the compressor (32) and the fuel cell (10),

wherein the expansion machine (23) arranged in the fuel supply path (21) is connected in a force-transmitting manner to the compressor (32) arranged in the air supply path (31) for driving the same.

The utility supply system (200) of claim 1, characterized in that the air supply system (30) further includes a bypass line (36) which branches downstream of the compressor (32) and upstream of the accumulator (33) from the air supply path (31) and downstream of the pressure accumulator (33) and upstream of the fuel cell (10) or the internal combustion engine in the air supply path (31) opens.

3. A resource supply system (200) according to claim 1, characterized in that the air supply system (30) further comprises a between the compressor (32) and the fuel cell (10) branched off from the air supply path (31) side arm, which the air supply path (31) the pressure accumulator (33) connects.

4. resource supply system (200) according to any one of the preceding claims, characterized in that a separating device (25) is provided which allows decoupling of the expansion machine (23) and the compressor (32) from each other.

5. Betnebsmittelversorgungssystem (200) according to any one of the preceding claims, characterized in that the compressor (32) exclusively by the

Expansion machine (23) is drivable.

6. resource supply system (200) according to any one of the preceding claims,

characterized in that the resource supply system (200) is arranged to pressurize the expander (23) with a fuel pressure of at least 20 bar, preferably with the full fuel pressure of the fuel pressure accumulator (22).

7. resource supply system (200) according to any one of the preceding claims,

characterized in that the expansion machine (23) is designed, the

Polytrop fuel relax.

8. Fuel cell assembly (100) with a fuel cell (10) and a

A resource supply system (200) according to any one of claims 1 to 7.

9. Motor vehicle with a fuel cell (10) or a gas-powered

An internal combustion engine and a resource supply system (200) according to any one of claims 1 to 7.