WO2010114511A1

WO2010114511A1 - Hybrid power system

Info

Publication number: WO2010114511A1
Application number: PCT/US2009/038008
Authority: WO
Inventors: Sitaram Ramaswamy
Original assignee: Utc Power Corporation
Priority date: 2009-03-24
Filing date: 2009-03-24
Publication date: 2010-10-07

Abstract

A hybrid power system includes a hydrogen fuel source that is a fuel cell in one example. An internal combustion engine includes intake and exhaust systems, at least one of which is configured to receive hydrogen from the hydrogen fuel source, in the examples. The fuel cell has an anode outlet in fluid communication with the intake and/or exhaust systems. The fuel cell is configured to use a portion of the hydrogen from a hydrogen storage container during a fuel cell operating mode. At least an amount of hydrogen from a remaining portion of the portion is provided to the intake and/or exhaust systems during a hydrogen disposal mode.

Description

HYBRID POWER SYSTEM

BACKGROUND

This disclosure relates to a hybrid power system that includes a hydrogen fuel cell and an internal combustion engine. More particularly, the disclosure relates to managing hydrogen within the system.

Many different hybrid configurations have been suggested for power systems. One hybrid power system includes an internal combustion engine and a hydrogen fuel cell. The internal combustion engine and fuel cell are operated independently with one another to increase the overall efficiency of the vehicle.

The fuel cell includes a cell stack assembly having cells that produce electricity in response to chemical reactions within the cell. In one type of fuel cell, hydrogen is provided from an onboard, high pressure hydrogen storage container to an anode side of the cell. Air is provided to a cathode side of the cell and is used to react with the hydrogen. The cell separates the hydrogen into hydrogen ions and electrons, which provide electricity. The hydrogen ions combine with oxygen in the air to produce water and heat.

Typically, only about ninety percent of the hydrogen is used in the chemical reaction with the fuel cell. The remaining, unused hydrogen is expelled from an anode outlet and must be managed in some manner. The hydrogen is difficult to store once it has been released from the hydrogen storage container. For example, hydrogen requires a considerable volume to store unless the hydrogen is highly pressurized.

SUMMARY

A hybrid power system includes a hydrogen fuel source that is a fuel cell in one example. An internal combustion engine includes intake and exhaust systems, at least one of which is configured to receive hydrogen from the hydrogen fuel source, in the examples. The fuel cell has an anode outlet in fluid communication with the intake and/or exhaust systems. The fuel cell is configured to use a portion of the hydrogen received from a hydrogen storage container during a fuel cell operating mode. At least a measurable amount of unused hydrogen from the fuel cell anode outlet is provided to internal combustion engine intake and/or exhaust systems during a hydrogen disposal mode.

These and other features of the disclosure can be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic view of a first hybrid power system. Figure 2 is a schematic view of a second hybrid power system. Figure 3 is a schematic view of a third hybrid power system. Figure 4 is a schematic view of a fourth hybrid power system.

DETAILED DESCRIPTION

Referring to the Figures, a vehicle 10 is schematically shown having a hybrid power system 12, in accordance with an embodiment of the disclosure. Example vehicles include, but are not limited to, trains, boats, buses, motorcycles and submarines. The hybrid power systems can also be used in stationary structures, if desired. The hybrid power system 12 may include an internal combustion (IC) engine

14 and a fuel cell 16. The IC engine 14 and fuel cell 16 cooperate with one another to efficiently power the vehicle 10 during a variety of operating conditions. One or both of the IC engine 14 and fuel cell 16 is coupled to a drive train 18 to propel the vehicle

10. The drive train 18 includes a transmission 26 that rotationally drives wheels 28.

The fuel cell 16 may be coupled to the transmission 26 through an electric motor 44. The arrangement shown in the Figures are exemplary only and should not be construed as limiting.

The IC engine 14 includes intake and exhaust systems 20, 30 in fluid communication with a combustion chamber 21. The intake system 20 delivers air to the combustion chamber 21 where it mixes with hydrocarbon fuel delivered by an injector 22, for example, to a desired air/fuel ratio. A hydrocarbon fuel tank 24 supplies a hydrocarbon fuel, such as diesel or gasoline, to the injector 22. The combustion products are expelled from the combustion chamber 21 through the exhaust system 30, which includes a catalytic converter 56. A controller 46 communicates with various sensors associated with the IC engine 14, fuel cell 16 and/or other vehicle systems. For example, the controller 46 communicates with an oxygen sensor 48 in the exhaust system 30 and other sensors 50, 52 to control the air/fuel ratio in the combustion chamber 21. In one example, the other sensors 50, 52 include an intake manifold pressure sensor, throttle position sensor, an intake temperature sensor, an exhaust temperature sensor, a humidity sensor and/or any other sensors that could provide information useful to the controller 46 in managing the operation of the IC engine 14 and fuel cell 16.

The fuel cell 16 includes an anode inlet 36 and an anode outlet 40. A hydrogen fuel source 32, such as a storage container, is fluidly coupled to the anode inlet 36 to supply the fuel cell 16 with hydrogen. The fuel cell 16 also includes a cathode inlet 38 and a cathode outlet 42. The cathode inlet 38 receives a reactant, such as oxygen within air. The hydrogen and oxygen chemically react to produce electricity within the fuel cell 16 that can be used to power various components of the vehicle, such as the electric motor 44. The fuel cell 16 typically only uses a portion of the hydrogen provided by the hydrogen fuel source 32. Any excess, remaining or unused air or effluent is typically expelled from the cathode outlet 42 to the outside environment. However, it is desirable to manage any excess, remaining or unused portion of hydrogen at the anode outlet 40. Accordingly, the below examples employ a hydrogen disposal mode in which excess hydrogen is used to further improve the efficiency of the vehicle 10.

Referring to the example shown in Figure 1, hydrogen from the anode outlet 40 is selectively supplied to the intake system 20 through a valve 54 that communicates with the controller 46. The hydrogen should be sufficiently diluted before entering the combustion chamber 21 given the comparatively high airflow through the intake system 20. Introducing hydrogen into the combustion chamber 21 affects the air/fuel ratio of the mixture. It is desirable to maintain an air/fuel mixture that closely approximates stoichiometric combustion to minimize undesirable emissions. To this end, the controller 46 determines the effects of the hydrogen on the air/fuel ratio and sends a signal to the valve 54 to obtain a desired air/fuel ratio based upon the amount of hydrogen provided to the intake system 20. The valve 54 selectively regulates the amount of hydrogen to the intake system 20 in response to the signal from the controller 46. A portion, or all, of the effluent exhausted from the cathode outlet 42 can be provided to the intake system 20, as shown in the vehicle 110 and the hybrid power system 112 of Figure 2. A second valve 58 is in communication with the controller 46. The second valve 58 is configured to selectively regulate the amount of air to the intake system 20 in response to another signal from the controller 46. The effluent exiting the cathode outlet 42 may be depleted of oxygen from the chemical reactions with the fuel cell 16. As a result, the mixture of hydrogen and effluent entering the intake system 20 may have the effect of leaning the air/fuel mixture within the combustion chamber 21. The controller 46 sends the other signal to the second valve 58 to regulate the mixture of hydrogen and effluent entering the intake system in order to obtain the desired air/fuel ratio based upon the amount of air provided to the intake system 20. The controller 46 may also calculate a dew point using humidity and temperature sensors to ensure that moistened effluent (due to product water from the chemical reactions within the fuel cell 16) does not have an undesired effect on the combustion process within the IC engine 14. The valves 54 and 58 are commanded by the controller 46 to manage the amount of moistened air from the cathode outlet 42 that enters the combustion chamber 21.

Air and/or hydrogen exhausted from the fuel cell 16 are provided to the exhaust system 30, as shown in example vehicles 210, 310 of Figures 3 and 4. Referring to the hybrid power system 212 of Figure 3, hydrogen from the anode outlet 40 is provided to a port 60 in the exhaust system 30 upstream from the catalytic converter 56. The hydrogen is combusted in the catalytic converter 56. A catalytic temperature may be monitored using a sensor 64, which is in communication with the controller 46, to ensure that the temperature within the catalytic converter 56 does not become undesirably high. The controller 46 regulates the amount of hydrogen and/or air provided to the catalytic converter 56 using valves 54, 58. The valves 54 and 58 also may act as one way flow control devices in order to prevent any back flow from the IC engine into the fuel cell. Referring to the hybrid power system 312 of Figure 4, the exhaust system 30 includes a heating element 62 (e.g. burner, etc.) thermally coupled to the catalytic converter 56. The heating element 62 receives hydrogen and/or air from the fuel cell 16 through the valves 54, 58, as determined by the controller 46, to heat the catalytic converter 56 to a desired temperature during cold conditions, for example, to quickly reach light-off for improved emissions control.

Although example embodiments have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.

Claims

1. A hybrid power system comprising: a fuel cell; and an internal combustion engine configured to receive hydrogen from the fuel cell.

2. The system according to claim 1, wherein the internal combustion engine includes intake and exhaust systems, at least one of the intake and exhaust systems configured to receive hydrogen from the fuel cell.

3. The system according to claim 2, wherein the fuel cell includes an anode outlet in fluid communication with and configured to provide hydrogen to the at least one of the intake and exhaust systems.

4. The system according to claim 3, comprising a hydrogen storage container in fluid communication with an anode inlet of the fuel cell and configured to supply hydrogen to the fuel cell, the fuel cell configured to use a portion of the hydrogen received during a fuel cell operating mode, and at least a measurable amount of hydrogen from a remaining portion of hydrogen is provided to the at least one of IC engine intake and exhaust systems during a hydrogen disposal mode.

5. The system according to claim 4, wherein the internal combustion engine includes a combustion chamber that is arranged between the intake and exhaust systems, and comprising a hydrocarbon fuel tank in fluid communication with the combustion chamber, and the hydrocarbon fuel tank is different than the hydrogen storage container.

6. The system according to claim 5, wherein the intake system is configured to receive at least a measurable amount of hydrogen.

7. The system according to claim 6, comprising a valve and a controller that is communication with the valve, the valve configured to selectively regulate the amount of hydrogen to the intake system in response to a signal from the controller.

8. The system according to claim 7, comprising at least one sensor in communication with the controller, the controller determining an air/fuel ratio from the at least one sensor and configured to send the signal to the valve to obtain a desired air/fuel ratio based upon the measurable amount of hydrogen provided to the intake system.

9. The system according to claim 8, wherein the fuel cell includes a cathode inlet configured to receive air and a cathode outlet configured to exhaust the air, the cathode exhaust in fluid communication with the IC engine intake system.

10. The system according to claim 9, comprising another valve in communication with the controller, the other valve configured to selectively regulate the amount of air to the IC engine intake system in response to another signal from the controller, the controller configured to send the other signal to the other valve to obtain the desired air/fuel ratio based upon the amount of air provided to the intake system.

11. The system according to claim 5, wherein the IC engine exhaust system is configured to receive the amount of hydrogen.

12. The system according to claim 11, wherein the IC engine exhaust system includes catalytic converter and a burner thermally coupled to the catalytic converter, the burner configured to receive the measurable amount of hydrogen during a converter warm-up mode.

13. The system according to claim 12, comprising a valve and a controller that is communication with the valve, the valve configured to selectively regulate the amount of hydrogen to the burner in response to a signal from the controller, the burner configured to heat the catalytic converter and combust the measurable amount of hydrogen for a predetermined parameter.

14. The system according to claim 13, wherein the fuel cell includes a cathode inlet configured to receive air and a cathode outlet configured to exhaust the air, the cathode exhaust in fluid communication with the exhaust system.

15. The system according to claim 11, wherein the exhaust system includes a catalytic converter and a port upstream from the catalytic converter, the port configured to receive the measurable amount of hydrogen.

16. The system according to claim 3, comprising a drive train coupled to the internal combustion engine and the fuel cell, the drive train including wheels and configured to receive rotational drive from at least one of the internal combustion engine and the fuel cell.

17. A method of managing hydrogen within a hybrid power system comprising: providing a hydrogen source; combusting a hydrocarbon fuel in an internal combustion engine; processing hydrogen from the hydrogen source in a fuel cell; and combusting hydrogen from the hydrogen source in the internal combustion

18. The method according to claim 17, wherein the internal combustion engine includes an intake system and an exhaust system, the hydrogen provided to the exhaust system and bypassing the intake system.

19. The method according to claim 17, wherein the fuel cell includes an anode outlet that is in fluid communication with the internal combustion engine, the anode outlet providing the amount of hydrogen to the internal combustion engine.

20. A vehicle comprising: a fuel cell including an anode outlet; an internal combustion engine configured to receive hydrogen from the anode outlet; and a drive train configured to receive drive from at least one of the fuel cell and the internal combustion engine.