Ion exchange cartridge for fuel cell applications

An ion exchange cartridge for a coolant system of a fuel cell stack is provided. The ion exchange cartridge includes a housing with an ion exchange resin disposed therein. The housing includes an inlet and at least one fluid-permeable outlet window configured for coolant to flow therethrough. The ion exchange cartridge is adapted to be removably disposed in the coolant system. An ion exchange cartridge assembly and a coolant tank assembly having the ion exchange cartridge are also provided.

FIELD OF THE INVENTION

The present disclosure relates to a fuel cell system and, more particularly, to an ion exchange cartridge for the fuel cell system.

BACKGROUND OF THE INVENTION

A fuel cell has been proposed as a clean, efficient and environmentally responsible energy source for electric vehicles and various other applications. In particular, the fuel cell has been identified as a potential alternative for the traditional internal-combustion engine used in modern vehicles.

One type of fuel cell is known as a proton exchange membrane (PEM) fuel cell. The PEM fuel cell typically includes three basic components: a cathode, an anode, and an electrolyte membrane. The cathode and the anode typically include a finely divided catalyst, such as platinum, supported on carbon particles and mixed with an ionomer. The electrolyte membrane is sandwiched between the cathode and the anode to form a membrane-electrolyte-assembly (MEA). The MEA is often disposed between porous diffusion media (DM) which facilitate a delivery of gaseous reactants, typically hydrogen and oxygen, for an electrochemical fuel cell reaction. Individual fuel cells can be stacked together in series to form a fuel cell stack. The fuel cell stack is capable of supplying a quantity of electricity sufficient to provide power to a vehicle.

During operation of the fuel cell stack, the fuel cell stack temperature is generally maintained within a desired range for the electrochemical fuel cell reaction. A coolant system having a coolant tank and coolant lines in fluid communication with the fuel cell stack is typically employed for this purpose. Coolant, such as substantially pure water, from a coolant tank is supplied to the fuel cell stack for regulating the temperature thereof. The coolant supplied to the fuel cell stack is typically desired to have a minimal electrical conductivity. If ions are present in the coolant, an electrical conductivity of the coolant increases and a power generation efficiency of the fuel cell stack decreases. To militate against the decrease in the fuel cell stack efficiency, an ion-exchange cartridge for removing ions in the coolant is typically employed in the coolant system.

Known ion exchange cartridges are disposed in-line between the coolant tank and the fuel cell stack. After sufficient usage, the exhausted ion exchange cartridge including a housing, connectors, and resin, must be replaced and properly discarded. Such service on in-line ion exchange cartridges is generally difficult. For example, access to the part of the engine compartment where the ion-exchange cartridge is disposed may be limited. Additionally, the line is necessarily opened to replace the in-line ion exchange cartridge, resulting in a draining of at least some of the coolant. An entry of contaminants from the environment into the coolant system during such service is therefore likely. A subsequent and undesirable clean-up of the coolant system following service is generally also required.

There is a continuing need for an ion exchange cartridge and method for servicing a coolant system having the ion-exchange cartridge that employs reusable parts, minimizes waste, minimizes a loss of the coolant during the service, and minimizes the exposure of the coolant system to contamination from the environment. Desirably, the ion-exchange cartridge also has an integrated housing with closing and sealing functions that facilitates a reusing and a refilling of the ion-exchange cartridge with service.

SUMMARY OF THE INVENTION

In concordance with the instant disclosure, an ion exchange cartridge and method for servicing a coolant system having the ion-exchange cartridge that employs reusable parts, minimizes waste, minimizes a loss of the coolant during the service, minimizes the exposure of the coolant system to contamination from the environment, and has an integrated housing with closing and sealing functions that facilitates a reusing and a refilling of the ion-exchange cartridge with service, is surprisingly discovered.

In one embodiment, an ion exchange cartridge for a coolant system of a fuel cell stack includes a housing adapted to contain an ion exchange resin therein. The housing has an inlet and at least one fluid-permeable outlet window configured for coolant to flow therethrough. The ion exchange cartridge is adapted to be removably disposed in the coolant system.

In a further embodiment, an ion exchange cartridge assembly for a coolant system of a fuel cell stack includes the ion exchange cartridge having the housing with the ion exchange resin disposed. The ion exchange cartridge assembly includes a bracket coupled to the ion exchange cartridge. The bracket is adapted for removal of the ion exchange cartridge from the coolant system.

In another embodiment, a coolant tank assembly (CTA) of a coolant system for a fuel cell stack includes a coolant tank having a coolant inlet and a coolant outlet. The coolant tank having an aperture formed therein. The CTA includes the ion exchange cartridge assembly removably disposed in the coolant tank and in fluid communication with the coolant inlet.

DETAILED DESCRIPTION OF THE INVENTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should also be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, are not necessary or critical.

FIG. 1shows a coolant system having a coolant tank assembly2(CTA) according to the present disclosure. The CTA2includes a coolant tank4having a coolant inlet6and a coolant outlet8. The coolant inlet6and the coolant outlet8are in fluid communication with a fuel cell stack (not shown), for example, via a coolant circuit. The coolant tank4is adapted to receive coolant that has been circulated through the fuel cell stack and store the coolant prior to a recirculation thereof. The coolant tank4shown is a multi-chambered coolant reservoir. A skilled artisan should appreciate that other configurations of the coolant tank4, for example, a single chambered coolant tank4, may be employed as desired. A plurality of coolant inlets6, disposed at either end of the coolant tank4, and a plurality of coolant outlets8, typically disposed at a bottom end of the coolant tank4, may also be employed.

The coolant tank4has an aperture10formed therein. An ion exchange cartridge assembly12is inserted through the aperture10and seated at a bottom14of the coolant tank4adjacent the coolant inlet6. The ion exchange cartridge assembly12is in fluid communication with the coolant inlet6and adapted for coolant to flow therethrough. The coolant flows through the ion exchange cartridge assembly12for removal of undesirable ions from the coolant prior to the coolant entering the coolant tank4, and subsequently the fuel cell stack.

With reference toFIGS. 1 and 2, the ion exchange cartridge assembly12includes an ion exchange cartridge16with a housing18. The housing18is adapted for an ion exchange resin to be disposed therein. The ion exchange resin may be a substantially water-insoluble material provided in the form of beads, for example. In one embodiment, the ion exchange resin is fabricated from an organic polymer substrate. As nonlimiting examples, the ion exchange resin may include at least one of a strongly acidic polymer, for example, having sulfonic acid groups, a strongly basic polymer, for example, having trimethylammonium groups, a weakly acidic polymer, for example, having carboxylic acid groups, and a weakly basic polymer, for example, having amino groups. As further nonlimiting examples, the ion exchange resin may include at least one of sodium polystyrene sulfonate (polyAMPS), poly(acrylamido-N-propyltrimethylammonium chloride) (polyAPTAC), and polyethylene amine. A skilled artisan should appreciate that other suitable ion exchange resins may be used as desired.

The ion exchange cartridge16has at least one fluid-permeable outlet window20formed in the housing18. In a particular embodiment, the ion exchange cartridge16has a plurality of outlet windows20arranged around the housing18. The outlet window20is configured for the coolant to flow therethrough from the coolant inlet6, through the ion exchange resin, and into the coolant tank4. A volume of the coolant flow through the ion exchange cartridge16may range from about 1 liter per minute to about 5 liters per minute, for example. In a particular embodiment, the volume of coolant flow through the ion exchange cartridge16is from about 2 liters per minute to about 4 liters per minute. A suitable coolant flow for the coolant system of the fuel cell stack may be selected as desired. A size of the ion exchange cartridge16may also be appropriately selected to accommodate a desired flow rate and to minimize pressure drop across the ion exchange cartridge16.

The housing18of the ion exchange cartridge16has a first end22with a first opening23formed therein. The housing18has a second end24with an inlet25formed therein. The inlet25is adapted for fluid communication with the coolant inlet6of the coolant tank4. The inlet25facilitates the flow of the coolant into the ion exchange cartridge16for removal of undesirable ions.

The ion exchange cartridge16includes a closure head26removably coupled to the housing14and adapted to seal the first opening23. The closure head26may have dimensions that allow the closure head26to be at least partially inserted into the first opening23of the housing14.

At least one of the housing inlet25and outlet window20may have a porous cover27, such as a mesh, disposed thereover. Suitable porous covers27may be selected as desired. For example, the porous cover27may be integrally molded with the housing18. The porous cover27may be over-molded to the housing18. In another embodiment, the porous cover27may be at least one of glued and welded, for example, to the housing18over the housing inlet25and the outlet window20. The porous cover27is adapted to keep the ion exchange resins within the housing18while the ion exchange cartridge16is disposed within the coolant tank4, and particularly while the coolant flows therethrough.

The housing18is adapted to be removably disposed in the coolant tank4. For example, the housing18may be a substantially cylindrical barrel that is inserted through the aperture10of the coolant tank4. In one embodiment, the ion exchange cartridge assembly12further includes a bracket28coupled to the ion exchange cartridge16. For example, the bracket28may be adapted to be coupled with the closure head26. The bracket28thereby enables a removal of the ion exchange cartridge16from the coolant tank4as desired. The bracket28may also have a length that allows the ion exchange cartridge16to be seated at a base of the coolant tank4when installed in the CTA2.

A cap30is coupled to the bracket28at an end of the bracket28opposite the ion exchange cartridge16. The cap30may be at least one of snap-on and threaded as desired. Other suitable types of caps30may also be employed. In a particular embodiment, the aperture10of the coolant tank4may be circumscribed by an outwardly extending, threaded lip (not shown). The threaded lip of the coolant tank4may cooperate with the threaded cap30to seal the aperture10of the coolant tank4during an operation of the ion exchange cartridge assembly12. For example, the cap30may include a flat sealing O-ring (not shown) for sealing the aperture10of the coolant tank4into which the ion exchange cartridge16is inserted.

The ion exchange cartridge assembly12, and in particular the ion exchange cartridge16, may be cost-effectively produced, for example, by an injection molding process as is known in the art. Other suitable processes for producing and assembling the ion exchange cartridge assembly12and the ion exchange cartridge16may be employed as desired.

Referring now toFIGS. 2 to 8, various embodiments of the ion exchange cartridge assembly12of the disclosure are described in further detail. The housing18of the ion exchange cartridge16is adapted to couple with the closure head26. As a nonlimiting example, the first end22of the housing18has at least one female clip feature32that cooperates with at least one male clip feature34formed on the closure head26. The female clip feature32may include, for example, an outwardly extending portion36having a clip opening38formed therein for receiving the male clip feature34. A skilled artisan should understand that the at least one female clip feature32may alternatively be formed on the closure head26and the at least one male clip feature may alternatively be formed on the housing18, as desired.

In a further embodiment, a first sealing member40, such as a first O-ring, is disposed between the closure head26and the first opening23of the housing18. It should be appreciated that a skilled artisan may select other suitable sealing members for use as the first sealing member40. The first sealing member40provides a sealing engagement between the closure head26and the housing18when the closure head26and the housing are18assembled to form the ion exchange cartridge16. The first sealing member40facilitates an opening of the ion exchange cartridge16when removed from the coolant tank4for replacement of exhausted ion exchange resin.

In a particular embodiment, the first sealing member40may be disposed in a first circumferential groove42formed in one of the housing18and the closure head26. It should be appreciated that the first sealing member40may be disposed on a surface of the closure head26and sandwiched between the surface and an inner wall of the housing18when the ion exchange cartridge16is assembled. A separating wall43of the closure head26and the first sealing member40of the closure head26militates against a flowing of the coolant through the first opening23of the housing18. The wall43and the first sealing member40also militate against any expelling of the ion exchange resin from the housing18due to pressure from the coolant flow.

The closure head26may also have at least one male bayonet fitting44. The male bayonet fitting44is adapted to couple with a female bayonet fitting46on the bracket28. The male bayonet fitting44may include a channel48that cooperates and the female bayonet fitting46. As a nonlimiting example, the male bayonet fitting44may include a plurality of outwardly extending clip features and the female bayonet fitting46may include a ring feature adapted to fit tightly over the clip features. One of ordinary skill in the art should appreciate that the male bayonet fitting44may alternatively be formed on the bracket28and that the female bayonet fitting46may alternatively be formed on the closure head26, if desired. Other suitable means for coupling the closure head26with the bracket28for removably disposing the ion exchange cartridge16within the coolant tank4may also be employed. For example, at least one of the closure head26, the bracket28, and the cap30may be integrally formed as a single part.

In an additional embodiment, the second end24of the housing18has a second sealing member50, such as a second O-ring. The second sealing member50may circumscribe the second end24of the housing18. The second sealing member50is adapted to sealingly seat within the coolant tank4in fluid communication with the coolant inlet6. For example, the second sealing member50may be disposed between the housing18and a seating feature (not shown) formed in a base of the coolant tank4in line with the coolant inlet6. The second sealing member50may thereby militate against the coolant flow bypassing the ion exchange cartridge16and directly entering the coolant tank4. As with the first sealing member40, the second sealing member50may be selected as desired. The second sealing member50may be disposed within a second circumferential groove52formed in the housing18at the second end24thereof.

Referring now toFIG. 9, a method of assembling the ion exchange cartridge assembly12of the present disclosure is provided. The method includes first providing the housing18with the second sealing member50, the closure head26with the first sealing member40, and the bracket28. The housing18is then filled with a suitable ion exchange resin. The closure head26is coupled to the housing18, for example, by inserting the closure head into the housing14until the male clip features34of the closure head26cooperate with the female clip features32of the housing18to militate against relative movement therebetween. Similarly, the method includes coupling the bracket28with the closure head26, for example, by inserting the male bayonet features44of the closure head26into the female bayonet fitting46of the bracket28until the channels48of the male bayonet fitting44cooperate with the female bayonet fitting46to militate against relative movement therebetween. The ion exchange cartridge assembly12is thereby assembled and prepared for installation in the coolant tank4.

The ion exchange cartridge assembly12is installed in the coolant tank4by inserting the ion exchange cartridge assembly12through the aperture10. The second end24of the ion exchange cartridge16is sealingly seated at the base of the coolant tank4in fluid communication with the coolant inlet6of the coolant tank4. The coolant tank4is then sealed with the cap30, for example, by twisting the cap30if threaded. It should be appreciated that the bracket28does not turn with the twisting of the cap30. Following a period of use, the ion exchange cartridge16may be removed form the coolant tank4by unsealing the cap30and pulling on the bracket28to unseat and remove the ion exchange cartridge16. The ion exchange cartridge assembly12may then be partially or completely disassembled and the exhausted ion exchange cartridge16recharged with new ion exchange resin. Alternatively, the exhausted ion exchange cartridge16may be replaced with a recharged ion exchange cartridge16having the new resin.

A skilled artisan should appreciate that the ion exchange cartridge assembly16has an optimized and robust size. The CTA2and the ion exchange cartridge assembly16of the present disclosure facilitate an ease in service and replacement of exhausted ion exchange resin, for example, at a supplier refilling station. In particular, it is surprisingly found that the clips32,34and the bayonets44,46of the present disclosure allow the ion exchange cartridge16to be removed and disassembled multiple times without employing specialized tooling to replace the ion exchange resin inside the ion exchange cartridge16.

Additionally, a loss of coolant upon service is minimized as the ion exchange cartridge16may simply be removed from the coolant tank4without breaking a coolant line, as is the practice with conventional, in-line ion exchange systems. Unlike conventional in-line systems, the ion exchange cartridge16may be recharged and recycled instead of being disposed of following removal. Similarly, exposure of the coolant to contamination, for example, through environmental contact is minimized with the CTA2and the ion exchange cartridge assembly16of the disclosure.

The position of the at least one window20in the ion exchange cartridge16may be selected so that the at least one window20is in substantially continuous contact with the coolant within the coolant tank4. It should therefore be understood that a contact between the ion exchange resin inside the ion exchange cartridge16with the coolant fluid inside the coolant tank4advantageously cleans the coolant regardless of whether the coolant is flowing through the ion-exchange cartridge16. Thus, the ion exchange cartridge16of the present disclosure may also clean the coolant during a shut-down mode of the coolant system.