Patent Application
20090226772
The present invention relates to fuel cells, and, more particularly, to supplying fuel to and removing waste from fuel cells.
A fuel cell, like an ordinary battery, provides direct current electricity from two electrochemical reactions. These reactions occur at electrodes to which reactants are fed. For example, in an alcohol combustion fuel cell, a negative electrode (i.e., anode) is maintained by supplying an alcohol-based fuel such as methanol, whereas a positive electrode (i.e., cathode) is maintained by supplying oxygen or air. When providing a current, fuel is electrochemically oxidized at an anode electro-catalyst to produce electrons, which travel through an external circuit to a cathode electro-catalyst where they are consumed together with oxygen in a reduction reaction. A circuit is maintained within the fuel cell by the conduction of protons in an electrolyte.
A fuel cell stack typically includes a series of individual fuel cells. Each fuel cell includes an anode and cathode pair. A voltage across each fuel cell is determined by the type of electrochemical reaction occurring in the cell. For example, the voltage can vary from 0 V to 0.9 V for a typical alcohol combustion single cell, depending upon the current generated. The current generated in the cell depends on the operating condition and design of the cell, such as electro-catalyst composition/distribution, active surface area of a membrane electrode assembly, characteristics of a gas diffusion layer, flow field design of an anode and cathode plates, cell temperature, reactant concentration, reactant flow and pressure distribution, reaction by-product or waste removal, and so forth. The reaction area of a cell, number of cells in series, and the type of electrochemical reaction in the fuel cell stack determine a current and hence a power supplied by the fuel cell stack. For example, the typical power of an alcohol combustion fuel cell stack can range from a few watts to several kilowatts. A fuel cell system typically integrates a fuel cell stack along with different subsystems for the management of water, fuel, waste, air, humidification, and heat. These subsystems are sometimes collectively referred to as the balance of plant.
Fuel cell systems are increasingly being used to power devices, such as forklifts, pallet loaders, automated-guided vehicles, and other material handling equipment. In order to successfully integrate fuel cell systems into an even wider range of devices, it is desirable to efficiently service the fuel cell systems. In particular, refueling and waste removal should be accomplished quickly, so as to reduce the downtime of a device that is powered by a fuel cell system. Also, refueling and waste removal should be accomplished in a manner that meets environmental and safety regulations and does not require extensive operator supervision.
It is against this background that a need arose to develop the refueling devices and related systems and methods described herein.
One aspect of the invention relates to a refueling device for servicing a fuel cell system. In one embodiment, the refueling device includes a fuel handling unit that includes a fuel port and a fuel conveyance unit connected to the fuel port. The fuel conveyance unit is configured to convey fuel from the refueling device to the fuel cell system via the fuel port. The refueling device also includes a waste handling unit that includes a waste port and a waste conveyance unit connected to the waste port. The waste conveyance unit is configured to convey waste from the fuel cell system to the refueling device via the waste port. The refueling device further includes a communication port and a refueling device controller connected to the fuel handling unit, the waste handling unit, and the communication port. The refueling device controller is configured to establish a communication link with the fuel cell system via the communication port, such that the fuel cell system directs operation of the fuel handling unit and the waste handling unit.
In another embodiment, the refueling device includes a common port configured to pass fuel and waste. The refueling device also includes a fuel conveyance unit and a waste conveyance unit that are each connected to the common port. The fuel conveyance unit is configured to convey the fuel along a fuel flow pathway passing through the common port, and the waste conveyance unit is configured to convey the waste along a waste flow pathway passing through the common port. The refueling device further includes a flow pathway selector that is connected between the common port and each of the fuel conveyance unit and the waste conveyance unit, and the flow pathway selector is configured to select between the fuel flow pathway and the waste flow pathway.
Another aspect of the invention relates to a fuel cell system. In one embodiment, the fuel cell system includes a fuel input port, a fuel storage unit connected to the fuel input port, a communication port, a first sensor connected to the fuel input port and the communication port, and a second sensor connected to the fuel storage unit. The first sensor is configured to produce a first output indicative of a connection between a refueling device and at least one of the fuel input port and the communication port, and the second sensor is configured to produce a second output indicative of a fuel level of the fuel storage unit. The fuel cell system also includes a fuel cell system controller connected to the first sensor, the second sensor, and the communication port. The fuel cell system controller is configured to direct operation of the refueling device via the communication port, and the fuel cell system controller is configured to direct conveyance of fuel from the refueling device to the fuel storage unit based on the first output and the second output.
A further aspect of the invention relates to a method for servicing a fuel cell system using a refueling device. In one embodiment, the method includes detecting a connection between the refueling device and the fuel cell system. The method also includes, responsive to detecting the connection, determining a fuel level of a fuel storage unit included in the fuel cell system. The method also includes, responsive to determining that the fuel level is below a threshold fuel level, initiating conveyance of fuel from the refueling device to the fuel storage unit. The method further includes, responsive to determining that the fuel level is at least the threshold fuel level, terminating conveyance of fuel from, the refueling device to the fuel storage unit.
Other aspects and embodiments of the invention are also contemplated. The foregoing summary and the following detailed description are not meant to restrict the invention to any particular embodiment but are merely meant to describe some embodiments of the invention.
For a better understanding of the nature and objects of some embodiments of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.
The following definitions apply to some of the components described with respect to some embodiments of the invention. These definitions may likewise be expanded upon herein.
As used herein, the singular terms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a sensor can include multiple sensors unless the context clearly dictates otherwise.
As used herein, the term, “set” refers to a collection of one or more components. Thus, for example, a set of sensors can include a single sensor or multiple sensors. Components of a set can be referred to as members of the set. Components of a set can be the same or different. In some instances, components of a set can share one or more common characteristics.
As used herein, the terms “optional” and “optionally” mean that the described event or circumstance may or may not occur, and that the description includes instances where the event or circumstance occurs and instances in which it does not.
As used herein, the terms “connect,” “connected,” and “connection” refer to an operational coupling or linking. Connected components can be directly coupled to one another or can be indirectly coupled to one another, such as via another set of components.
Attention first turns to
As illustrated in
Advantageously, the illustrated embodiment includes control and safety mechanisms to provide safe and regulated operations during refueling and waste removal. In particular, the fuel cell system controller 114 and the refueling device controller 122 operate in conjunction to control the refueling and waste removal operations in a substantially automated manner and in compliance with environmental and safety regulations. The refueling and waste removal operations can occur sequentially or in parallel, the latter of which allows enhanced servicing throughput and reduces the downtime of the target device 106. In addition, the illustrated embodiment allows multiple fuel cell systems, each having its own distinct refueling and waste removal requirements, to be serviced by the same refueling device 116, with little or no modification and operator supervision when servicing the fuel cell systems. As further described herein, this can be accomplished by establishing a communication link between the fuel cell system controller 114 and the refueling device controller 122, thereby allowing the fuel cell system controller 114 to control the refueling device 116 in accordance with particular refueling and waste removal requirements of the fuel cell system 102.
Attention next turns to
In the illustrated embodiment, the refueling device 200 includes a fuel input port 204, an internal fuel storage unit 206, a fuel conveyance unit 208, a fuel filtering unit 210, a fuel output port 212, and a set of sensors 214, which collectively correspond to a fuel handling unit to supply fuel to the fuel cell system 202. Various components of the fuel handling unit are connected to one another to define a fuel flow pathway extending between the fuel input port 204 and the fuel output port 212. It should be recognized that the particular implementation of these components is provided by way of example, and these components can be combined, sub-divided, or re-ordered in accordance with another implementation. Also, certain of these components can be optionally omitted for another implementation.
Referring to
The internal fuel storage unit 206 can be implemented as a relatively rigid fuel storage tank or as a relatively non-rigid or expandable fuel storage tank. In the case of the refueling device 200 operating at a fixed location, the internal fuel storage unit 206 can be optionally omitted. In the case of a mobile implementation, the internal fuel storage unit 206 provides onboard storage of fuel, and the fuel conveyance unit 208 conveys the fuel to the fuel cell system 202 in situ. The fuel conveyance unit 208 can be implemented as a pump along with other optional flow control or flow restrictive components to meet safety regulations and a desired level of servicing throughput. In the illustrated embodiment, the fuel conveyance unit 208 conveys fuel along a substantially unidirectional flow pathway passing through the fuel output port 212. However, it is also contemplated that the fuel conveyance unit 208 can convey fuel along a bi-directional flow pathway. In such manner, the refueling device 200 can. remove substantially all fuel from the fuel cell system 202 to facilitate its shipment to another location.
As illustrated in
The sensors 214 are connected to the internal fuel storage unit 206, the fuel conveyance unit 208, and the fuel filtering unit 210, and operate to monitor an operational status of these connected components. The particular implementation of the sensors 214 can vary depending upon the particular implementation of these connected components and the desired complexity for related control mechanisms. For example, the sensors 214 can monitor fault events related to the internal fuel storage unit 206. In particular, a leak sensor can produce an output indicative of a critical fault event that terminates refueling operations, while a level sensor can produce an output indicative of an empty or low fuel level. In the case of an expandable implementation of the internal fuel storage unit 206, a pressure sensor can be used in place of a level sensor to monitor fuel levels. For implementations in which fuel is actively pumped or re-circulated, an electrical current or voltage sensor can monitor pumping or re-circulating operations and indicate a fault event, such, as a pump failure, a line blockage, or a vacuum condition. The sensors 214 can also monitor fuel flow rates and pressures, such as using in-line flow meters and pressure gauges.
In the illustrated embodiment, the refueling device 200 also includes a waste input port 216, a waste conveyance unit 218, a waste filtering unit 220, an internal waste storage unit 222, a waste output port 224, and a set of sensors 226, which collectively correspond to a waste handling unit to remove waste from the fuel cell system 202. Various components of the waste handling unit are connected to one another to define a waste flow pathway extending between the waste input port 216 and the waste output port 224. It should be recognized that the particular implementation of these components is provided by way of example, and these components can be combined, sub-divided, or re-ordered in accordance with another implementation. Also, certain components can be optionally omitted for another implementation. In the illustrated embodiment, the waste flow pathway is separate from the fuel flow pathway to reduce or minimize mixing of waste and fuel. However, it is also possible that the waste flow pathway and the fuel flow pathway can share a common pathway for handling fuel and waste.
Referring to
The internal waste storage unit 222 and the waste conveyance unit 218 can be implemented in a similar manner as the internal fuel storage unit 206 and the fuel conveyance unit 208, respectively. For example, the internal waste storage unit 222 can be implemented as a relatively rigid waste storage tank or as an expandable waste storage tank. In the case of the refueling device 200 operating at a fixed location, the internal waste storage unit 222 can be optionally omitted. In the case of a mobile implementation, the refueling device 200 stores waste onboard in the internal waste storage unit 222, and subsequently conveys the waste to an external waste storage unit (not illustrated). Similar to the fuel conveyance unit 208, the waste conveyance unit 218 can be implemented as a pump along with other optional flow control or flow restrictive components. In the illustrated embodiment, the waste conveyance unit 218 conveys waste from the fuel cell system 202 along a substantially unidirectional flow pathway passing through the waste input port 216. However, it is also contemplated that the waste conveyance unit 218 can convey waste along a bi-directional flow pathway. In such manner, the waste output port 224 can be optionally omitted, and the refueling device 200 can remove waste from the fuel cell system 202, via the port 216, and can subsequently convey the waste, via the same port 216, to an external waste storage unit (not illustrated).
As illustrated in
The sensors 226 are connected to the internal waste storage unit 222, the waste filtering unit 220, and the waste conveyance unit 218, and operate to monitor an operational status of these connected components. The sensors 226 can be implemented in a similar manner as the sensors 214, and can include a particular combination of leak sensors, level sensors, pressure sensors, electrical current or voltage sensors, flow meters, or pressure gauges.
Still referring to
The refueling device 200 further includes a user interface 230 and a power source 232, which can be implemented as a battery. The user interface 230 provides indications of operational status to an operator, including alerts regarding any fault events, and the power source 232 supplies electrical power to the refueling device controller 228 and other active components of the refueling device 200. In general, the refueling device 200 can derive electrical power from any of three sources: (1) the power source 232; (2) an external power source (not illustrated), such as an alternating current power source; and (3) the fuel cell, system 202. In the case of the refueling device 200 operating at a fixed location, electrical power can be supplied by either the fuel cell system 202 or by an external power source, in which case the onboard power source 232 can be optionally omitted. For a mobile implementation of the refueling device 200, electrical power can be supplied by either the fuel cell system 202 or by the onboard power source 232.
The fuel cell system 202 includes a fuel input port 236 and a fuel storage unit 238, which are connected to one another to define a fuel flow pathway that supplies fuel to a set of fuel cells 240. The fuel input port 236 can be implemented in a similar manner as the fuel output port 232, and can include a mechanism to facilitate engaging and disengaging with the refueling device 200. The fuel storage unit 238 can be implemented as a relatively rigid fuel storage tank or as an expandable fuel storage tank, A set of sensors 242 are connected to the fuel storage unit 238, and operate to monitor an operational status of the fuel storage unit 238. The particular implementation of the sensors 242 can vary depending upon the particular implementation of the fuel storage unit 238 and the desired complexity for related control mechanisms. For example, the sensors 242 can include a level sensor or a pressure sensor to produce outputs indicative of fuel levels. Other implementations of the sensors 242 can include a particular combination of leak sensors, flow meters, or pressure gauges.
Referring to
The fuel cell system 202 further includes a fuel cell system controller 250, which is connected to and directs operation of various components of the fuel cell system 202. In particular, the fuel cell system controller 250 tracks the operational status of the fuel cell system 202 in accordance with outputs of the sensors 242 and 248. In the illustrated embodiment, the fuel cell system controller 250 is implemented as a master controller that directs refueling and waste removal operations by controlling the refueling device controller 228. In conjunction, the fuel cell system controller 250 tracks the operational status of the refueling device 200 as conveyed by the refueling device controller 228. This is accomplished via a communication port 252, which can be implemented to provide a wired connection or a wireless connection. It is contemplated that the master-slave assignments can be switched for another implementation, with the refueling device controller 228 serving as a master controller, and the fuel cell system controller 250 serving as a slave controller.
A set of sensors 254 are connected to the fuel input port 236, the communication port 252, and the waste output port 246, and operate to monitor a connection status of the ports 236, 252, and 246. The sensors 254 can include a proximity or contact sensor to produce an output indicative of a fluid connection between the ports 212 and 236 or between the ports 216 and 246, and a proximity or contact sensor to produce an output indicative of a wired or wireless connection between the ports 234 and 252. The fuel cell system controller 250 tracks the connection status of the ports 236, 252, and 246 in accordance with outputs of the sensors 254, so as to automatically detect an operator's intention to service the fuel cell system 202.
The operation of the fuel cell system controller 250 can be further understood with reference to
Referring to
In the refueling operation state, the fuel cell system controller 250 tracks the operational status of the fuel cell system 202 as well as the operational status of the refueling device 200. In particular, the fuel cell system controller 250 determines fuel and waste levels of the fuel cell system 202. If the fuel level of the fuel cell system 202 is below a threshold fuel level, such as a pre-determined or operator-selectable fuel level, the fuel cell system controller 250 assumes control of the refueling device 200, via the refueling device controller 228, and initiates refueling operations (block 308). If the waste level of the fuel cell system 202 is at or above a threshold waste level, such as a pre-determined or operator-selectable waste level, the fuel cell system controller 250 initiates waste removal operations (block 310). The refueling and waste removal operations can occur sequentially or in parallel.
If a fault event is detected while in the refueling operation state, the fuel cell system controller 250 transitions to the fault state, and alerts an operator via the user interface 230 (block 312). Examples of fault events include an overcurrent condition of the fuel conveyance unit 208, an overcurrent condition of the waste conveyance unit 218, a leak of the internal fuel storage unit 206 of the refueling device 200, an empty or low fuel level of the internal fuel storage unit 206, a leak of the internal waste storage unit 222 of the refueling device 200, a full waste level of the internal waste storage unit 222, the refueling operations taking longer than a particular time interval, and the waste removal operations taking longer than a particular time interval. In the case of a critical fault event, such as a leak, the fuel cell system controller 250 can substantially immediately terminate the refueling and waste removal operations. In the event of a non-critical fault event, the fuel cell system controller 250 can direct the refueling and waste removal operations to be continued in a safe manner, albeit at a reduced performance level. The fuel cell system controller 250 can reference mass flow characteristics of fuel and waste, characteristics of the fuel and waste handling units, and other information contained in an associated memory to control and monitor the flow of fuel and waste. If the flow characteristics are not within expected ranges, the fuel cell system controller 250 can detect a fault event, and can alert the operator via the user interface 230.
In the absence of a fault event, the fuel cell system controller 250 terminates the refueling operations once the fuel level of the fuel cell system 202 is at or above the threshold fuel level. Also, once the waste level of the fuel cell system 202 is below the threshold waste level, the fuel cell system controller 250 terminates the waste removal operations. The fuel cell system controller 250 then transitions to a refueling wrap-up operation state (block 314).
In the refueling wrap-up operation state, the fuel cell system controller 250 alerts the operator regarding completion of refueling and waste removal, via the user interface 230. Also, the fuel cell system controller 250 waits for the operator to disconnect the refueling device 200 with respect to the fuel input port 236, the communication port 252, and the waste output port 246. If disconnection does not take place within a particular time interval, such as a pre-determined or operator-selectable time interval, the fuel cell system controller 250 transitions to the fault state (block 312). Otherwise, the fuel cell system controller 250 terminates the communication link with the refueling device controller 228, and transitions back to the normal operation state (block 300).
The foregoing provides a general overview of some embodiments of the
invention. Attention next turns to
implementations in. accordance with other embodiments of the invention.
Referring to
Referring to
Referring to
Referring to
Still referring to
Some embodiments of the invention relate to a computer-readable storage medium having computer code stored thereon for performing various computer-implemented operations. The media and computer code may be those specially designed and constructed for the purposes of the invention, or they may be of the kind well known and available to those having skill in the computer software arts. Examples of computer-readable media include, but are not limited to: magnetic storage media such as hard disks, floppy disks, and magnetic tape; optical storage media such as Compact Disc/Digital Video Discs (“CD/DVDs”), Compact Disc-Read Only Memories (“CD-ROMs”), and holographic devices; magneto-optical storage media such as floptical disks; and hardware devices that are specially configured to store and execute program code, such as Application-Specific Integrated Circuits (“ASICs”), Programmable Logic Devices (“PLDs”), and ROM and RAM devices. Examples of computer code include, but are not limited to, machine code, such as produced by a compiler, and files containing higher-level code that are executed by a computer using an interpreter. For example, an embodiment of the invention may be implemented using Java, C++, or other object-oriented programming language and development tools. Additional examples of computer code include, but are not limited to, encrypted code and compressed code.
Some embodiments of the invention can be implemented using computer code in place of, or in combination with, hardwired circuitry. For example, with reference to
While the invention has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention as defined by the appended claims. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, method, or process to the objective, spirit and scope of the invention. All such modifications are intended to be within the scope of the claims appended hereto. In particular, while the methods disclosed herein have been described with reference to particular operations performed in a particular order, it will be understood that these operations may be combined, sub-divided, or re-ordered to form an equivalent method without departing from the teachings of the invention. Accordingly, unless specifically indicated herein, the order and grouping of the operations are not limitations of the invention.
This application claims the benefit of U.S. Provisional Application Ser. No. 60/967,104, filed on Aug. 30, 2007, the disclosure of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60967104 | Aug 2007 | US |
