U.S. patent application number 09/770486 was filed with the patent office on 2002-08-01 for hydrogen recharging system for fuel cell hydride storage reservoir.
Invention is credited to Kelley, Ronald J., Muthuswamy, Sivakumar, Pennisi, Robert W., Pratt, Steven D..
Application Number | 20020100682 09/770486 |
Document ID | / |
Family ID | 25088709 |
Filed Date | 2002-08-01 |
United States Patent
Application |
20020100682 |
Kind Code |
A1 |
Kelley, Ronald J. ; et
al. |
August 1, 2002 |
Hydrogen recharging system for fuel cell hydride storage
reservoir
Abstract
A self-contained hydrogen recharging system (5) for a fuel cell
metal hydride storage canister (100). A water reservoir (10)
provides water (15) to an electrolyzer (20), where the water is
converted into hydrogen gas (22) and oxygen gas (24). The hydrogen
gas is dried (26) and then stored in an accumulator (30). When the
metal hydride storage canister is ready to be refilled, it is
connected by the user to the recharging system. A heat exchanger
(55) heats the fuel cell hydride storage canister prior to transfer
of the stored hydrogen gas, and then cools the fuel cell hydride
storage canister during transfer of the stored hydrogen gas. The
hydrogen gas stored in the accumulator is rapidly transferred to
the hydride storage canister by means of a pump (60) and stowed in
the canister as a metal hydride.
Inventors: |
Kelley, Ronald J.; (Coral
Springs, FL) ; Pratt, Steven D.; (Plantation, FL)
; Muthuswamy, Sivakumar; (Plantation, FL) ;
Pennisi, Robert W.; (Boca Raton, FL) |
Correspondence
Address: |
MOTOROLA, INC
INTELLECTUAL PROPERTY SECTION
LAW DEPT
8000 WEST SUNRISE BLVD
FT LAUDERDAL
FL
33322
US
|
Family ID: |
25088709 |
Appl. No.: |
09/770486 |
Filed: |
January 29, 2001 |
Current U.S.
Class: |
204/266 ;
204/262; 204/274; 204/278 |
Current CPC
Class: |
H01M 8/04007 20130101;
Y02E 60/50 20130101; H01M 8/065 20130101; C01B 3/0005 20130101;
H01M 8/04089 20130101; H01M 8/04208 20130101; H01M 8/0656 20130101;
Y02E 60/32 20130101 |
Class at
Publication: |
204/266 ;
204/262; 204/278; 204/274 |
International
Class: |
C25B 009/00; C25D
017/00; C25C 007/00 |
Claims
What is claimed is:
1. A hydrogen recharging system for fuel cell hydride storage
reservoirs, comprising: an electrolyzer to hydrolyze liquid water
to hydrogen gas and oxygen gas, said electrolyzer connected to a
water supply; a hydrogen gas accumulator; a dryer situated between
and connected to the electrolyzer and the accumulator; and wherein
hydrogen gas produced by the electrolyzer is dried in the dryer and
then stored in the accumulator such that when a user connects the
fuel cell hydride storage reservoir to the hydrogen recharging
system, the stored hydrogen gas is rapidly transferred from the
accumulator to the hydride storage reservoir, to be retained in the
hydride storage reservoir in the form of a metal hydride.
2. The system as described in claim 1, further comprising a heat
exchanger to cool the connected fuel cell hydride storage reservoir
during transfer of the stored hydrogen.
3. The system as described in claim 1, further comprising a heat
exchanger to heat the connected fuel cell hydride storage reservoir
prior to transfer of the stored hydrogen, and wherein a pump is
used to evacuate the fuel cell hydride storage reservoir during
heating.
4. The system as described in claim 1, wherein a pump is used to
evacuate the fuel cell hydride storage reservoir.
5. The system as described in claim 4, further comprising a heat
exchanger to heat the connected fuel cell hydride storage reservoir
during evacuation of the reservoir, and then to cool the connected
fuel cell hydride storage reservoir during transfer of the stored
hydrogen.
6. The system as described in claim 1, further comprising a vent on
the electrolyzer to vent oxygen produced by the electrolyzer to the
surrounding environment.
7. The system as described in claim 1, wherein the accumulator
further comprises a compressor.
8. The system as described in claim 1, further comprising a charge
meter for measuring the amount of hydrogen transferred to the fuel
cell hydride storage reservoir.
9. The system as described in claim 1, wherein the system is
contained in a desktop housing less than or equal to one cubic foot
in volume.
10. A self-contained hydrogen recharging system for a fuel cell
metal hydride storage reservoir, comprising: a water supply
connected to an electrolyzer for converting liquid water to
hydrogen and oxygen gas; hydrogen storage means comprising an
accumulator and a compressor; a dryer situated after the
electrolyzer; and wherein hydrogen gas produced by the electrolyzer
is stored in the hydrogen storage means; a heat exchanger to heat
the fuel cell hydride storage reservoir prior to transfer of the
stored hydrogen gas, and then to cool the fuel cell hydride storage
reservoir during transfer of the stored hydrogen gas; and wherein
upon connection of the fuel cell hydride storage reservoir to the
hydrogen recharging system by a user, the stored hydrogen gas is
rapidly transferred to the hydride storage reservoir and stowed in
the reservoir as a metal hydride.
11. The system as described in claim 7, further comprising a vent
on the electrolyzer to vent oxygen produced by the electrolyzer to
the surrounding environment.
12. The system as described in claim 7, further comprising a charge
meter for measuring the amount of hydrogen transferred to the fuel
cell hydride storage reservoir.
13. The system as described in claim 7, further comprising a vacuum
pump.
14. A hydrogen recharging system for fuel cell hydride storage
reservoirs, comprising: an electrolyzer to hydrolyze liquid water
to hydrogen gas and oxygen gas, said electrolyzer connected to a
water supply; a hydrogen gas accumulator; and wherein hydrogen gas
produced by the electrolyzer is stored in the accumulator such that
when a user connects the fuel cell hydride storage reservoir to the
hydrogen recharging system, the stored hydrogen gas is rapidly
transferred from the accumulator to the hydride storage reservoir,
to be retained in the hydride storage reservoir in the form of a
metal hydride.
Description
TECHNICAL FIELD
[0001] This invention relates in general to fuel cells, and more
particularly to a system for rapidly charging hydrogen fuel to the
fuel storage container.
BACKGROUND
[0002] In recent years, nearly all electronic devices have been
reduced in size and made lightweight, in particular portable
electronic devices. This advancement has been made possible, in
part, by the development of new battery chemistries such as
nickel-metal hydride, lithium ion, zinc-air, and lithium polymer
that enable larger amounts of power to be packaged in a smaller
container. However, since these are secondary or rechargeable
batteries, they need to be recharged upon depletion of their
electrical capacity. This is typically performed by connecting the
battery to a battery charger that converts alternating current
(typically 110 volts AC) to a low level direct current (typically
2-12 volts DC). The charging cycle typically lasts a minimum of 1-2
hours, and more commonly 4-14 hours. Although the new batteries are
a tremendous advancement over the previous generations of
batteries, they still suffer from the need for sophisticated
charging regimens and the slow charging rates.
[0003] Some have sought to replace electrolytic batteries with
small fuel cells. Simply put, fuel cells catalytically convert a
hydrogen molecule to hydrogen ions and electrons, and then extract
the electrons through a membrane as electrical power, while
oxidizing the hydrogen ions to H.sub.2O and extracting the
byproduct water. The tremendous advantage of fuel cells is the
potential ability to provide significantly larger amounts of power
in a small package (as compared to a battery). However, the problem
of how to replenish the supply of hydrogen fuel to the spent fuel
cell still seeks an elegant and practical solution before
widespread consumer acceptance occurs. Some have sought to use
methanol as the source of hydrogen, by catalytically converting or
`reforming` the methanol using exotic schemes. At the current state
of the art, fuel cells directly powered by methanol are still a
laboratory curiosity, and significant technical obstacles remain to
be overcome. Even with seven decades behind us since the Hindenberg
disaster, consumers remain wary of hydrogen gas, and thus there is
no infrastructure to provide hydrogen to refill exhausted fuel
cells. Thus, even though the energy conversion portion of the fuel
cell has been refined to the point where it is commercially viable
for small devices, the problem of how to safely provide hydrogen to
consumers in small quantities remains to be commercially
implemented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The sole drawing FIGURE is a schematic representation of a
self-contained hydrogen recharging system for a fuel cell metal
hydride storage canister in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0005] A self-contained hydrogen recharging system for a fuel cell
metal hydride storage canister. A water reservoir provides water to
an electrolyzer, where the water is converted into hydrogen gas and
oxygen gas. The hydrogen gas is stored in an accumulator, and is
dried either prior to or after storing. When the metal hydride
storage canister is ready to be refilled, it is connected by the
user to the recharging system. A heat exchanger heats the fuel cell
hydride storage canister prior to transfer of the stored hydrogen
gas, and then cools the fuel cell hydride storage canister during
transfer of the stored hydrogen gas. The hydrogen gas stored in the
accumulator is rapidly transferred to the hydride storage canister
and stowed in the canister as a metal hydride. While the
specification concludes with claims defining the features of the
invention that are regarded as novel, it is believed that the
construction, method of operation and advantages of the invention
will be better understood from a consideration of the following
description in conjunction with the drawing FIGURE.
[0006] Referring now to the single drawing FIGURE, a self-contained
hydrogen recharging system 5 for a fuel cell metal hydride storage
canister consists of several elements. A vessel, container or
canister 10 holds a supply of water 15 that will subsequently be
converted into hydrogen and oxygen. The container 10 can, of
course, assume many forms, such as an open container, a can, a
capsule, a tank, a reservoir, etc. Additionally, a water supply
line (not shown) connected to, for example, a municipal water
source or other high purity water supply, can be substituted for
the container 10. The water supply line can be permanently
connected or arranged to be removably coupled. The water 15 is
hydrolyzed into hydrogen and oxygen in the electrolyzer 20.
Electrolysis (also known as hydrolysis) is a well known double
decomposition reaction involving the splitting of water into its
ions and the formation of a weak acid or base or both. This is
brought about by passing a direct current through a platinum anode
and a platinum cathode that are immersed in the water. The overall
decomposition reaction is: 1
[0007] At the cathode, hydrogen ions are produced, that combine
into H.sub.2 molecules, and are collected above the surface of the
water as hydrogen gas 22. At the anode, oxygen ions are likewise
produced and combine into O.sub.2 molecules 24, and are similarly
collected above the surface of the water. The oxygen can either be
collected or vented to the atmosphere. In fuel cell systems that
utilize pressurized oxygen as a source of oxidant (rather than
ambient air) one would collect and store the oxygen in a manner
similar to that used for the hydrogen. In most cases, however, the
oxygen will simply be vented to the atmosphere. The hydrogen gas 22
is dried by passing through a dryer 26 where any residual water
vapor is removed. It is important to have a dry source of hydrogen
for stable fuel cell operation. The gas can be dried either prior
to storage in the accumulator, or during the charging of the metal
hydride canister, and can be dried through any number of schemes,
but we suggest that a commercial desiccant such as silica gel or 3
Angstrom molecular sieves be used, as they are easily obtainable
and easily replaceable or regenerated when exhausted. The hydrogen
gas 22 (either dried or not dried) is stored in an accumulator 30.
The accumulator 30 is intended to be a storage system, and as such
can assume numerous configurations, such as, for example, an
expandable bladder, a pressurized vessel, or a container with a
piston that can store the hydrogen at or slightly above atmospheric
pressure. The pressure generated at the electrolyzer 20 by the
production of hydrogen gas 22 can be used to `pump` the hydrogen
gas into the accumulator 30 and store it at pressure. Of course,
this pressure is limited, and if one wishes to store additional
quantities of hydrogen gas, it needs to be compressed and stored at
elevated pressures. This can be accomplished by incorporating a
mechanical compressor into the accumulator 30. The compressor (not
shown) compresses the hydrogen so that it can be stored in a rigid
pressurized container. Storage of pressurized hydrogen requires
requisite safety considerations, and it is assumed that the skilled
reader will adhere to the well-known safety precautions in the
handling of pressurized hydrogen.
[0008] When the hydride storage container 100 in the user's fuel
cell becomes empty and needs to be replenished, one connects it to
the self-contained hydrogen recharging system 5 and the hydrogen
gas 22 held in the accumulator 30 is rapidly transferred via a
valve 62 to the hydride storage container 100. For purposes of
clarity, it should be noted that the hydride storage container 100
is part of the user's fuel cell system, and can be integral to the
fuel cell or it can be a removable component, such as a vessel with
a quick disconnect. The hydride storage container 100 is typically
filled with a material that stores the hydrogen fuel as a metal
hydride, rather than as hydrogen gas. Thus, when the hydrogen gas
is charged into the user's hydride storage container 100, it
undergoes a chemical reaction that converts the material to a metal
hydride. Those skilled in the art will appreciate that large
quantities of hydrogen can be safely stored in the metal hydride
form. For example, many modern electrochemical rechargeable
batteries use nickel-metal hydride as the media for storing
electrochemical energy, and this material is very similar to that
used in the hydride storage container 100. Since the hydrogen-metal
hydride reaction is exothermic (produces heat), a heat exchanger 55
is provided to remove the heat of reaction. Cooling the hydride
storage container 100 during charging allows for rapid recharging.
The charging time using our invention compares rather favorably to
the long charging time associated with present day batteries if
examined from a recharge rate standpoint. As an example, a 7-volt
radio battery with 1500 milliamp-hour capacity takes approximately
two hours to recharge, at a recharge rate of 5.25 watt-hours per
hour. A state of the art 7 volt fuel cell system of comparable
physical size to the above battery has approximately 10 times the
energy capacity, providing 15,000 milliamp-hour capacity, but can
be recharged using our invention in only ten (10) minutes, thereby
recharging at a rate of 630 watt-hours per hour.
[0009] The heat exchanger 55 can also include a heating system.
Over time and use, the material in the hydride storage container
100 may collect contaminants and lose some hydride storage
capacity, typically ranging from 10-15% loss. The material can be
purified and `refreshed` using the present invention in the
following way. The heat exchanger 55 is operated in a `heating`
mode, and heats the hydride canister 100 prior to charging,
allowing the release of residual hydrogen and other contaminants,
while an optional vacuum pump 60 evacuates the contaminant gases
through purge valve 62. Then, the hydride canister 100 is cooled
and recharged as described previously above.
[0010] In an alternative embodiment, a charge meter 40 monitors and
measures the amount of hydrogen gas that is transferred to the
spent fuel cell canister 100. In its simplest form, the charge
meter is a flow meter. In order to provide a package that is
commercially viable, the entire system as described above is
optionally contained in a housing 70, similar to present day
desktop battery chargers, typically less than or equal to one cubic
foot in volume. Thus, the safety conscious consumer can have a
small, simple, effective method for rapidly recharging spent fuel
cell canisters. Our invention provides recharging times for fuel
cells up to 100 times faster than present day electrochemical
battery charging methods. Since water and electricity are the only
raw materials needed to replenish the system, our invention can be
used virtually anywhere with minimal cost.
[0011] While the preferred embodiments of the invention have been
illustrated and described, it will be clear that the invention is
not so limited. Numerous modifications, changes, variations,
substitutions and equivalents will occur to those skilled in the
art without departing from the spirit and scope of the present
invention as defined by the appended claims. For example, the
instant invention as shown and described can also be used with
other hydrogen based fuel cell storage systems, such as carbon
nanofiber or nanotube storage systems, and additionally,
pressurized hydrogen storage vessels.
* * * * *