Patent Application
20130298999
Aspects of the present invention relate generally to the field of fuel cell, and more specifically to the gas flow control mechanism used by the fuel cell system.
A typical fuel cell system has an anode, the electrolyte, and a cathode, whereas the electrolyte is sandwiched between the anode and cathode. When a catalyst oxidizes the fuel at the anode, the fuel is transformed into a positively charged ion and a negatively charged electron. Then, the negatively charged electron causes electric current by passing through a load circuitry, while the positively charged ion passes through the electrolyte to reach the cathode. At the cathode, the positively charged ion can unite with the negatively charged electron and react with another chemical. Usually, the fuel is hydrogen and the chemical at the cathode is oxygen.
To ensure that the fuel cell operates efficiently, the flow of hydrogen must be maintained. In addition, if the hydrogen pressure is outside of the safety range, the system may become unstable and may raise safety concerns.
Accordingly, there is a need in the art for an gasflow management system that provides a safety module to ensure that the gasflow pressure inside remains within a pre-specified range.
An gasflow management system comprises an input terminal to receive an input source with an input pressure level, a pressure-reducing valve to reduce the input pressure level to a reduced pressure level, a connector to connect the pressure-reducing valve to a release valve, a pressure sensor, and an output terminal, whereas the release valve is adapted to release a part of the input source if a first condition is met, and the pressure sensor is adapted to sense an output pressure level. In addition, the gasflow management system may further comprise a switch valve with a first state and a second state, wherein the input source may reach the pressure-reducing valve when the switch valve operates at the first state and the input source may not reach the pressure-reducing valve when the switch valve operates at the second state.
The foregoing and other aspects of various embodiments of the present invention will be apparent through examination of the following detailed description thereof in conjunction with the accompanying drawing figures in which similar reference numbers are used to indicate functionally similar elements.
a) and (b) are a simplified diagrams illustrating components of an air management system according to an embodiment of the present invention.
Embodiments of the present invention provide an gasflow management system that provides a safety module to ensure that the gasflow pressure remains within a pre-specified range inside the fuel cell system.
The switch valve 1 may have at least an “on” status and an “off” status such that when it is set at the “on” status, it will allow the input source to pass through, and when it is set at the “off” status, the input source will be blocked from further passage. The switch valve 1 may be an electromechanical valve. In a preferred embodiment, the switch valve 1 is a solenoid valve, which may be controlled by an electric current through a solenoid.
Once the input source passes through the switch valve, it may reach a pressure-reducing valve 2. Through its settings, the pressure-reducing valve 2 may reducing the system input pressure to the reduced pressure. As discussed, the system input pressure often needs to be reduced to a certain range to avoid damages to the operation, or accidents involving burst pipes/conduits from the abnormal pressure. Hence, the reduced pressure from the pressure-reducing valve 2 may be the preferred operating pressure. A person of ordinary skill in the art would notice that the order of the switch valve 1 and pressure-reducing valve 2 is exchangeable.
Even though the pressure-reducing valve 2 may serve to reduce the input pressure, because the risk caused by the burst pipes or damages resulted from operating with abnormal pressure are too high, the gasflow management system may benefit from additional safety mechanisms. Thus, the reduced pressure from the pressure-reducing valve 2 is passed to the pressure sensor 4 and relief valve 5 through the connector 3. The connector 3 may be a four-way connector, with terminals corresponding to the output of the pressure-reducing valve 2, the pressure sensor 4, the relief valve 5, and the output terminal 102. In one embodiment of the present invention, the connector 3 is formed by attaching two three-way connectors together, whereas the first three-way connector has terminals corresponding to the output of the pressure-reducing valve 2, the output terminal 102, and a terminal of the second three-way connector, and the second three-way connector has terminals corresponding to the pressure sensor 4, the relief valve 5, and a terminal of the first three-way connector. A person of ordinary skill in the art would appreciate that there are many ways to pass pressure from one position to another position.
Once the pressure reaches the release valve 5, the release valve 5 may release the air if the pressure it senses is over the cutoff pressure. Once the air is released, the pressure may be reduced to prevent the abnormal pressure from damaging the operation. The release valve 5 may be of any type of valve (electronic, mechanical, or electromechanical) that can be use to control or limit the pressure in a system.
Once the pressure is passed to the pressure sensor 4, the pressure sensor 4 may pass the pressure reading to the controller such that the controller may decide to shut down the gasflow management system 100 or the entire system. For example, the controller may decide to shut down the entire system if the reading is higher or lower than the safety range.
In sum, according to an embodiment of the present invention, the system output pressure at the output terminal 102 may be the reduced pressure from the pressure-reducing valve 2 subject to the cutoff pressure associated with the release valve 5 and the pressure reading sensed by the pressure sensor 4.
In one embodiment of the present invention, the input source is hydrogen with pressure around 5-6 Bar, and the preferred operation pressure is around 0.3-0.4 Bar. In this case, after passing through the pressure-reducing valve 2, the pressure of the hydrogen is reduced to 0.3-0.4 Bar. The cutoff pressure for the release valve 5 may be set at 1 Bar. Thus, when the pressure-reducing valve 2 operates normally, the reduced pressure will be around 0.3-0.4 Bar, the release valve 5 will not release the hydrogen, and the system output pressure at output terminal 102 will also be around 0.3-0.4 Bar. On the other hand, when the pressure-reducing valve 2 suffers from dysfunction, the reduced pressure may be outside the preferred operation range. For example, if the reduced pressure is 1.5 Bar, then it is higher than the cutoff pressure for the release valve 5, thereby triggering the release valve 5 to release the air until the pressure is close to 1 Bar. At this time, the pressure sensor 4 may also alarm the controller of the abnormal condition and the controller may decide whether to shut down the operation. Also, if the reduced pressure is 0.1 Bar, it will not trigger the release valve 5, but the pressure reading may be passed from the pressure sensor 4 to the controller such that the controller knows that there is inadequate pressure at the output terminal 102.
Once at the pressure-reducing valve 202, the system input pressure is reduced to the reduced pressure and the air is then passed, through the connector 203, to the release valve 205, the pressure sensor 204, and the stack 230. When the pressure-reducing valve 202 is reducing the pressure, it may release some of the air inside the pressure-reducing valve 202 to the output terminal 220.
When the air reaches the release valve 205, the release valve 205 may release the air if the pressure it detects is above the cutoff pressure. Releasing the air may keep the pressure below or close to the cutoff pressure. The released air may be ejected at the output terminal 220.
Also, the pressure sensor 204 may pass the pressure reading to the controller 207 through electric connection 247. If the controller 207 determines that the pressure is not safe for operation, the controller may shut down the operation. For example, the controller may shut down the switch valve 201, or it may cut off the power of the operation.
At stack 230, the input source may function as a fuel to the fuel cell system. For example, when the input source is hydrogen, it may enter the fuel cell system to create electric current and produce output air after reacting with oxygen at the cathode.
The output air from the stack 230 may then enter the switch valve 206. Similar to the switch valve 217, the switch valve 206 may be connected to the controller 207 through electric connection 267. During its “on” state, the switch valve may allow the output air to reach the output terminal 220. During its “off” state, the output air may not pass through the switch valve 206.
The foregoing discussion identifies types of gasflow management systems that may be used to manage the hydrogen in a fuel cell system. Another gasflow management system may be adopted for the gasflow of oxygen.
The foregoing discussion identifies functional blocks that may be used in the fuel cell systems constructed according to the various embodiments of the present invention. In practice, these gasflow management systems may be applied to a variety of devices. While the invention has been described in detail above with references to some embodiments, variations within the scope and spirit of the invention will be apparent to those of ordinary skill in the art. Thus, the invention should be considered as limited only by the scope of the appended claims.
