U.S. patent application number 12/409084 was filed with the patent office on 2009-10-08 for fuel cell heater.
This patent application is currently assigned to Hunter Manufacturing Co.. Invention is credited to John L. Creed.
Application Number | 20090253092 12/409084 |
Document ID | / |
Family ID | 41133597 |
Filed Date | 2009-10-08 |
United States Patent
Application |
20090253092 |
Kind Code |
A1 |
Creed; John L. |
October 8, 2009 |
FUEL CELL HEATER
Abstract
A self-powered space heater comprises a fan, a burner, a heat
exchanger and an fuel cell assembly. The fan generates an air flow.
The burner is positioned downstream of the fan and communicates
therewith. The burner produces a hot gas. The heat exchanger is
positioned downstream of the burner and is operatively connected
therewith for receiving at least some of the hot gas. The heat
exchanger provides heat for an associated enclosure. The fuel cell
assembly provides electrical energy to operate the space heater.
The fuel cell assembly is operatively connected to the burner for
receiving at least some of the hot gas. The fuel cell assembly
includes a fuel cell component and a heat compartment for
generating heat to heat the fuel cell component. A thermal output
of the burner provides sufficient hot gas to operate both the heat
exchanger and the fuel cell assembly.
Inventors: |
Creed; John L.; (Niles,
OH) |
Correspondence
Address: |
Fay Sharpe LLP
1228 Euclid Avenue, 5th Floor, The Halle Building
Cleveland
OH
44115
US
|
Assignee: |
Hunter Manufacturing Co.
|
Family ID: |
41133597 |
Appl. No.: |
12/409084 |
Filed: |
March 23, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61042809 |
Apr 7, 2008 |
|
|
|
Current U.S.
Class: |
432/220 ;
165/121 |
Current CPC
Class: |
H01M 8/04007 20130101;
F24H 2240/10 20130101; Y02E 60/50 20130101; F24H 3/065 20130101;
H01M 8/04074 20130101 |
Class at
Publication: |
432/220 ;
165/121 |
International
Class: |
F24H 3/02 20060101
F24H003/02; F28F 13/12 20060101 F28F013/12 |
Claims
1. A self-powered space heater comprising: a fan for generating an
air flow; a burner positioned downstream of the fan and
communicating therewith, the burner producing a hot gas; a heat
exchanger positioned downstream of the burner and operatively
connected therewith for receiving at least some of the hot gas, the
burner and heat exchanger providing primary heat for an associated
enclosure; and a fuel cell assembly for providing electrical energy
to operate the space heater, the fuel cell assembly being
operatively connected to the burner for receiving at least some of
the hot gas, the fuel cell assembly including a fuel cell component
and a heat compartment for generating heat to heat the fuel cell
component, wherein a thermal output of the burner provides
sufficient hot gas to operate both the heat exchanger and the fuel
cell assembly.
2. The space heater of claim 1, wherein the fuel cell component is
separated from the heat compartment by a mantel, the mantel
comprising one of a solid plate for allowing the fuel cell
component to be heated via radiant heat within the heat compartment
and a perforated plate for allowing radiation and convection flow
from the heat compartment to the fuel cell component.
3. The space heater of claim 1, further comprising a hot gas
conduit connected to the fuel cell assembly, and a variable flow
restrictor connected to the hot gas conduit, the variable flow
restrictor being configured to regulate gross BTU by throttling a
predetermined amount of hot gas flow through the fuel cell
assembly.
4. The space heater of claim 3, wherein the fuel cell assembly
includes at least one energy conversion unit located within the
heat compartment, the at least one energy conversion unit being
preheated and generally maintained at a predetermined operating
temperature by regulation of the variable flow restrictor.
5. The space heater of claim 1, wherein the fuel cell assembly
includes a reformer for obtaining a hydrogen-rich reformate.
6. The space heater of claim 5, wherein the fuel cell assembly
further includes a fuel cell processor located within the heat
compartment, the fuel cell processor being connected to a source of
fuel and a source of water, the fuel cell processor configured to
use steam for the reformation process.
7. The space heater of claim 1, further comprising an enclosure for
accommodating the burner and the heat exchanger.
8. The space heater of claim 7, wherein the enclosure also
accommodates the fuel cell assembly.
9. The space heater of claim 1, further comprising a blower located
downstream of the fuel cell assembly, wherein spent by-pass hot
gases and effluent from the fuel cell assembly is re-introduced
into the burner via the blower.
10. The space heater of claim 1, further comprising a blower
located downstream of the fuel cell assembly, wherein spent by-pass
hot gases and effluent from the fuel cell assembly is directed into
the heat exchanger via the blower.
11. The space heater of claim 10, further comprising a hot gas
restrictor positioned between the blower and the heat exchanger for
creating a pressure differential for providing a lower pressure
within the heat exchanger.
12. The space heater of claim 1, wherein the fuel cell assembly
further includes a housing for accommodating the heat compartment
and the fuel cell component.
13. The space heater of claim 1, further comprising a second fuel
cell assembly positioned in series with the fuel cell assembly,
wherein the second fuel cell assembly is operatively connected to
the burner for receiving at least some of the hot gas.
14. A self-powered space heater comprising: a fan for generating an
air flow; a burner positioned downstream of the fan and
communicating therewith for producing a hot gas; a first fuel cell
assembly operatively connected to the burner for receiving the hot
gas produced by the burner; a second fuel cell assembly operatively
connected to the burner for receiving hot gas produced by the
burner, the second fuel cell assembly being positioned in series
with the first fuel cell assembly, the first and second fuel cell
assemblies providing electrical energy to operate the space heater;
and a heat exchanger positioned downstream of the first and second
fuel cell assemblies and providing heat for an associated
enclosure, wherein a thermal output of the burner used for space
heating exceeds a thermal input required for power generation.
15. The space heater of claim 15, wherein one of the first and
second fuel cell assemblies includes a fuel cell component and a
heat compartment for generating heat to heat the fuel cell
component and the other of said first and second fuel cell
assemblies includes a heat compartment and a reformer located
within the heat compartment.
16. The space heater of claim 15, further comprising a hot gas
conduit operatively connected to one of the first and second fuel
cell assemblies and a variable flow restrictor operatively
connected to the hot gas conduit, the variable flow restrictor
being configured to regulate gross BTU by throttling a
predetermined amount of hot gas flow through the respective fuel
cell assembly.
17. The space heater of claim 15, further comprising a blower
located downstream of the first fuel cell assembly and second fuel
cell assembly, wherein spent by-pass hot gases and effluent from
the first and second fuel cell assemblies are directed into one of
the burner and heat exchanger via the blower.
18. The space heater of claim 17, further comprising a hot gas
restrictor positioned between the blower and the heat
exchanger.
19. A self-powered space heater comprising: a fan for generating an
air flow; a burner positioned downstream of the fan and
communicating therewith for producing a hot gas; a first fuel cell
assembly operatively connected to the burner for receiving the hot
gas produced by the burner; a second fuel cell assembly operatively
connected to the burner for receiving the hot gas produced by the
burner, the first and second fuel cell assemblies providing
electrical energy to operate the space heater; a heat exchanger
positioned downstream of the first and second fuel cell assemblies;
and a blower located downstream of the first fuel cell assembly and
second fuel cell assembly, wherein spent by-pass hot gases and
effluent from the first and second fuel cell assemblies are
directed into one of the burner and heat exchanger via the
blower.
20. The space heater of claim 19, further comprising an enclosure
for housing the burner, the heat exchanger and at least one of the
first and second fuel cell assemblies.
Description
RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Patent Application Ser. No. 61/042,809, filed 7 Apr. 2008, the
disclosure of which is incorporated herein by reference.
BACKGROUND
[0002] The present disclosure generally relates to heaters such as
self-powered heaters, and particularly, to the replacement of
thermoelectric generators currently used in a self-powered heater
by the integration of an electrochemical generation fuel cell that
provides a percentage of total combustion gases for heating. The
combustion gases are created from liquid fuels and a common burner
that has a fire rate or hot gas output sized to provide soft or
hard wall shelter heat with the use of a breathable air heat
exchanger.
[0003] Space heaters have wide spread success and have been in
production for the military for several years. A space heater is
generally one of three types, namely, non-powered, powered and
self-powered. The non-powered heater is generally a "light it with
a match" type vaporizing convection heater that comes in various
BTU outputs. The powered heater requires external power, such as
power generated from a generator or from a local power grid. The
self-powered heater provides forced air heat and has all of the
features of a powered heater except that no external power is
required. The self-powered heater generally is thermostat
controlled, producing burner turn down rates with built in
diagnostic and prognostic controls. The self-powered heater
typically operates by the manipulation of a single switch.
[0004] In military application, the self-powered heater is
primarily used to heat soft and hard wall shelters in military
field conditions, but have use in any application where space
heating is desirable. The self-powered heater can be operated in
ambient temperatures to -60.degree. F., and from sea level to
10,000 feet. The self-powered heater can operate on liquid fuel,
such as diesel, bio fuels and kerosene, such as JP-8 and Jet-A.
[0005] The self-powered heater generally uses an internal
thermoelectric generator integrated within a main hot gas stream to
extract a portion of the combustion heat to provide electricity for
heater operation. Due to the required heat output, the amount of
hot gas BTUs used for electrical generation is considerably less
than the BTUs applied to a breathable hot air heat exchanger.
Depending upon the operation cycle, excess electrical power is
available for export power after an internal battery is fully
charged. Current self-powered heaters use the export power for
electrical heating that is added internally to the heated air
stream.
[0006] The current art of the fuel cell industry is to increase
electrical conversion efficiency and reduce balance of plant system
cost per electrical watt produced. To increase the overall or
apparent efficiency, fuel cell generators are being integrated into
combined chill heat (CHP) cogeneration applications and combined
chill heat and power (CCHP) tri-generation applications. Even
though fuel cell generators are being integrated into CHP for home
or business use, the waste heat output is not sufficient to be used
for primary heat but can be used for low level heating. Additional
heat and electrical power is required in order to provide the
desired comfort level during peak cold weather heat load
demands.
[0007] Conventional fuel cell generators cannot produce sufficient
electrical wattage during high building demand periods. Fuel cells
are typically designed to operate very efficiently using the least
amount of fuel energy for the conversion to electrical output. The
waste heat of many fuel cell applications is used to heat liquids
or an air stream. This efficient operation limits the heat output
of the fuel cell. Using the fuel cell electrical output to augment
the rejected heat by using resistive heating can be
counterproductive due to having less electrical power available for
building demands.
[0008] Conventional fuel cell cogeneration designs for buildings
utilize a fuel cell with an electrical output capacity (kW) that is
near the time-averaged electrical power consumption rate for the
building and with a heat generation capacity that is useful for
meeting building heating needs. The actual onsite time-variable
power demand (kW) is met by a combination of the cogeneration
electrical power produced on sight and electrical power from the
public electrical power grid or another external power source. When
heat from the cogeneration fuel cell is insufficient to heat the
building, an auxiliary heater, operated typically by burning fuel,
supplements or augments the heat provided by the cogeneration of
the fuel cell. The ability of using a fuel cell as a primary or
single source space heater is limited due to this efficiency.
[0009] The following list of patents relate to cogeneration heat
and power. However, this type of fuel cell integration, when used
for primary heating, provides insufficient waste heat. Therefore,
the patents further disclose provisions for external electrical
and/or additional fuel burner augmentation.
[0010] WO 2005/047776 teaches a liquid cooled fuel cell system and
cogeneration (CHP) of building heat. The system comprises of an
auxiliary heater which is used when a primary heat exchanger is
insufficient to provide desired space heating. The auxiliary heater
can be connected to an external electric power source.
[0011] U.S. Pat. No. 6,054,299 teaches a fuel cell for the
production of electricity, with a heating, ventilation and cooling
system using waste heat generated by the fuel cell. An
interface-exchanging element can be adapted to receive thermal
energy from an incoming fluid having an elevated temperature. By
having the ability to operate an additional burner source, the fuel
cell low thermal output can be augmented during high heating
demands.
[0012] GB 2404007 discloses an air heater comprising electrical air
heating elements powered by a fuel cell unit.
[0013] As is evident from the above prior art, buildings that
derive some or all of their electrical needs from a fuel cell
require a second burner or an additional resistive heating device
for adequate space heating comfort during the winter season. Using
the rejected heat and power output of a fuel cell for primary space
heating is not practical due to the increased cost, size and weight
of a cogenerated fuel cell that is sized to produce electrical
resistive and combustion heat outputs sufficient for total space
heating requirements.
[0014] The following list of patents relate to start-up burners and
combustors.
[0015] US Patent Application Publication No. 2005/0257427 relates
to a start-up burner for rapidly heating a catalyst in a reformer
as well as related methods and modules. The module can further
contain an auxiliary burner adapted for warming fluids in the
module.
[0016] U.S. Pat. No. 7,086,853 is directed to a start-up combustor
for a fuel cell having a filter used to trap soot that is operated
during start up.
[0017] U.S. Pat. No. 6,007,620 discloses a fuel cell system with a
combustor-heated reformer capable of operating a combustor to heat
a fuel processor over a wide range heat outputs.
[0018] U.S. Pat. No. 6,451,465 B1 teaches a method for operating a
combustor in a fuel cell system to heat a fuel processor by
monitoring temperature and regulation of fuel flows.
[0019] U.S. Pat. No. 6,777,123 discloses combustor temperature
control of a fuel cell power plant. A combustor generates heat from
the combustion of fuel. The combustion stall temperature of the
combustor is controlled by regulating fuel flow.
[0020] As is evident from the above prior art, space heating by
using a single burner for the combustion is insufficient as a
provider of primary building heat, even if combined with the
teachings of integrating burners and combustors with a fuel cell.
Also lacking in the prior art is the ability to switch between
available fielded fuels, such as diesel, kerosene, DF-A, Jet-A,
JP-5 and JP-8. The additional concern of combustion inefficiencies
with altitude changes renders these approaches ineffective for a
space heater application.
[0021] Further, a deficiency of current fuel cell designs that
operate on diesel, bio fuels and kerosene when used in a
co-generation primary heater application is the required time from
a cold start to rated power and heat output. The heating of the
fuel cell component is a managed thermal process requiring time for
component normalization, reformer heating, water thawing, water
vaporization and related system and subsystem component warming
depending upon the type of fuel cell used. A military self-powered
heater is required to provide heat within minutes from the time the
operator or thermostat is turned on. Component warming before fuel
cell operation and heat output can be a lengthy process delaying
sufficient hot air output. A self-powered heater begins to provide
heat airflow within minutes after burner start. A starting battery
is used for initial burner operation and heater air flow. The
battery is sized to provide the necessary wattage capacity to
operate the heater components until the generator is on line
producing operational power and subsequent battery re-charging.
[0022] Another deficiency of current fuel cell designs when used in
a co-generation primary heater application becomes apparent when
the application requires a higher heat output than is available
from capturing all of the fuel cell's waste heat and electrical
output. Sufficient resistive heating required for space heating
will increase the heat output, but will also increase cost, weight
and size of the fuel cell. For example, a 35,000 BTU heat output
will need electrical power for a breathable re-circulation air fan,
combustion blower, fuel system and related balance of plant. To
provide a 35,000 BTU output, the fuel cell generator would be sized
in excess of 10 KW output to provide the needed balance of plant
power and the resistive heating current. Weight and size become
excessive when compared to a current 35,000 BTU self-powered
thermoelectric heater.
[0023] Yet another deficiency of current fuel cell designs when
used in a co-generation primary heater application is the burner
used for starting, reforming or exhaust gas management. The burner,
which is sized and directly coupled to the fuel cell component for
fuel cell operation, has the inability to increase combustion for
additional space heating.
[0024] Another deficiency is the inability to operate in cold
temperatures of -60.degree. F. This severe cold operation is a
standard requirement for shelter heating. Current fuel cell heat
recovery methods are overly efficient, not addressing dew point
condensation during severe cold start up and subsequent ice buildup
in heat recovery and exhaust systems during severe cold starting
and operation.
[0025] Another deficiency is that current fuel cell component
integration requires thermal coupling of components for operation,
such as a reformer being integrated within the same hot zone as a
cell stack. This makes repair in the field difficult requiring
subcomponent removal to gain access, remove and replace components
such as the reformer.
[0026] Taken individually or as a whole, the prior art fails to
provide an overall design for a practically implemented forced air,
multi-fueled warm air heating system that provides space heating
for soft and hard wall shelters while simultaneously operating a
fuel cell that provides electrical power for safe and efficient
heater operation.
[0027] Thus, there is a need to have a single heat source to supply
sufficient hot gases for use as a space heater that can
simultaneously provide a hot zone used for fuel cell component
start up and operation. Accordingly, the present disclosure
provides a space heater which overcomes certain difficulties with
the prior art designs while providing better and more advantageous
overall results.
BRIEF DESCRIPTION
[0028] According to one aspect of the present disclosure, a
self-powered space heater comprises a fan, a burner, a heat
exchanger and a fuel cell assembly. The fan generates an air flow.
The burner is positioned downstream of the fan and communicates
therewith. The burner produces a hot gas. The heat exchanger is
positioned downstream of the burner and is operatively connected
therewith for receiving at least some of the hot gas. The burner
and the heat exchanger provide primary heat for an associated
enclosure. The fuel cell assembly provides electrical energy to
operate the space heater. The fuel cell assembly is operatively
connected to the burner for receiving at least some of the hot gas.
The fuel cell assembly includes a fuel cell component and a heat
compartment for generating heat to heat the fuel cell component. A
thermal output of the burner provides sufficient hot gas to operate
both the heat exchanger and the fuel cell assembly.
[0029] According to another aspect of the present disclosure, a
self-powered space heater comprises a fan for generating an air
flow and a burner positioned downstream of the fan and
communicating therewith for producing a hot gas. A first fuel cell
assembly is operatively connected to the burner for receiving the
hot gas produced by the burner. A second fuel cell assembly is
operatively connected to the burner for receiving hot gas produced
by the burner. The second fuel cell assembly is positioned in
series with the first fuel cell assembly. The first and second fuel
cell assemblies provide electrical energy to operate the space
heater. A heat exchanger is positioned downstream of the first and
second fuel cell assemblies and provides heat for an associated
enclosure. A thermal output used of the burner for space heating
exceeds a thermal input required for power generation.
[0030] According to another aspect of the present disclosure, a
self-powered space heater comprises a fan for generating an air
flow and a burner positioned downstream of the fan and
communicating therewith for producing a hot gas. A first fuel cell
assembly is operatively connected to the burner for receiving the
hot gas produced by the burner. A second fuel cell assembly is
operatively connected to the burner for receiving the hot gas
produced by the burner. The first and second fuel cell assemblies
provide electrical energy to operate the space heater. A heat
exchanger is positioned downstream of the first and second fuel
cell assemblies. A blower is located downstream of the first fuel
cell assembly and second fuel cell assembly. Spent by-pass hot
gases and effluent from the first and second fuel cell assemblies
are directed into one of the burner and heat exchanger via the
blower.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a schematic diagram of a conventional fuel fired,
hot air space heater.
[0032] FIG. 2 is a schematic diagram of a conventional self-powered
heater.
[0033] FIG. 3 is a schematic diagram of a fuel cell self-powered
space heater according to one aspect of the present disclosure.
[0034] FIG. 4 is a schematic diagram of a fuel cell self-powered
space heater according to another aspect of the present
disclosure.
[0035] FIG. 5 is a schematic diagram of a fuel cell self-powered
space heater according to yet another aspect of the present
disclosure.
[0036] FIG. 6 is a schematic diagram of a fuel cell self-powered
space heater according to still yet another aspect of the present
disclosure.
[0037] FIG. 7 is a schematic diagram of a heat compartment of the
fuel cell space heaters of the present disclosure according to one
aspect of the present disclosure.
[0038] FIG. 8 is a schematic diagram of a reformer for the heat
compartment of FIG. 7.
[0039] FIG. 9 is a schematic diagram of a fuel processor for the
heat compartment of FIG. 7.
[0040] FIG. 10 is a schematic diagram of a heat compartment of the
fuel cell space heaters of the present disclosure according to
another aspect of the present disclosure.
[0041] FIG. 11 is a schematic diagram of a fuel cell self-powered
space heater according to still yet another aspect of the present
disclosure.
[0042] FIG. 12 is a schematic diagram of a fuel cell self-powered
space heater according to still yet another aspect of the present
disclosure.
[0043] FIG. 13 is a schematic diagram of a mantel for the heat
compartment of FIGS. 7 and 10 according to one aspect of the
present disclosure.
[0044] FIG. 14 is a schematic diagram of a mantel for the heat
compartment of FIGS. 7 and 10 according to another aspect of the
present disclosure.
DETAILED DESCRIPTION
[0045] It should, of course, be understood that the description and
drawings herein are merely illustrative and that various
modifications and changes can be made in the structures disclosed
without departing from this disclosure. Like numerals refer to like
parts throughout the several views. It will also be appreciated
that the various identified components of the space heater
disclosed herein are merely terms of art that may vary from one
manufacturer to another and should not be deemed to limit the
present disclosure.
[0046] With reference to FIG. 1, a schematic of a conventional fuel
fired, hot air space heater 105 is illustrated. The heater is the
type which that would operate on externally supplied electrical
power from a local power grid or a generator. The heater 105
includes an enclosure 115 for housing a burner 111 operably
connected to a heat exchanger 112. A fan 114 is provided at an
inlet of the enclosure for generating air flow through the
enclosure. The enclosure 115 is configured to manage the cooling
air flow created by the fan 114 and to protect the burner 111 and
heat exchanger 112 from environmental conditions. The burner 111
provides the combustion process and supplies hot gas through a gas
conduit 117 to the heat exchanger. Spent hot gas is expelled to the
atmosphere by an exhaust pipe 113. Air flow created by the fan
travels around the burner, through and around the heat exchanger
contained by the enclosure leaving as a heated breathable air
stream 116.
[0047] The burner 111 provides an atomization process and air
mixing. The atomization process can be vaporizing, air atomized by
using a small compressor or blower, spinner, or high-pressure
nozzle (not shown). The atomized fuel is introduced to combustion
airflow and ignited to produce a flame pattern that is managed
within the burner. The hot gases leaving the burner can still have
a visible flame pattern of unburned fuel depending upon the type of
atomization process selected and the downstream requirements of the
thermal qualities of the exiting hot gas. Thus, the hot gas conduit
117 is shown to visualize the collection of burner hot gasses;
although, the heat exchanger 112 can be directly connected to the
burner 111. The heat exchanger 112 can be a multi-pass type which
is designed to be radial with multiple passes connected with
crossover tubes. The heat exchanger 112 provides cooling airflow
between the multiple passes and crossover tubes with lesser air
flow around an outer area.
[0048] With reference to FIG. 2, a schematic of a conventional
self-powered heater 110 using a thermoelectric generator 50 is
illustrated. A battery 25 is provided for starting and post purging
the self-powered heater. The battery is recharged by the
thermoelectric generator, thus, no external power is required for
operation of the heater. The air inlet fan 114 draws air with or
without a return duct (not shown) and creates an air flow through
the enclosure 115. The burner 111 provides the combustion process
for supplying hot gas through a hot gas conduit 117a to the
thermoelectric generator 50. The generator supplies hot gas through
a hot gas conduit 117b to the heat exchanger 112, the hot gas
exiting the heat exchanger via the exhaust pipe 113. Air flow
created by the fan 114 exits the self-powered heater 110 with or
without a supply air duct (not shown) as a heated breathable air
stream.
[0049] The thermoelectric generator 50 is integrated within the hot
gas flow created by the burner 111. The hot gases are directed and
circulated within the thermoelectric generator 50 for efficient
heating. The hot gases exiting the generator 50 are introduced into
the heat exchanger 112 for primary heat transfer into the cooling
airflow. The majority of thermal transfer into the breathable air
stream is from the heat exchanger 112. The outer area of the
thermoelectric generator 50 is usually finned to increase cold
junction thermal transfer into the cooling breathable airflow
created by the fan 114.
[0050] In the description of the present disclosure below, the fuel
cell or fuel cell assembly is at times described as a single unit
even though it can contain various designs and types of components
that are required by the type of fuel cell. It would be known to
those skilled in the art that the various fuel cell components
require heat or specific ratios of oxygen to hydrocarbon for
operation. The use of the term fuel cell or fuel cell assembly for
clarity is used to include such components. The present disclosure
is capable of supplying by-passed hot gas that can be treated in
various ways in a hot zone, referred to as a heat compartment, for
proper operation of these various types and configurations of fuel
cell generator components.
[0051] Generators that can use direct injection of carbonaceous
fuels, thermally integrated vaporizer-reformers, fuel cell
oxidation facilitators, liquid anode, preheating and operation of a
carbon-oxygen fuel cell, startup heating, heating the reformer and
fuel cell in its own optimal temperature range simultaneously,
removing moisture and purging components after fuel cell shut down
and the re-burning of residual hydrogen or fuel cell exhaust
by-products are a few examples of the integration flexibility
achieved by using hot by-pass gas from a high BTU out-put burner
intended for space heating.
[0052] As will be described in greater detail below, the present
disclosure generally relates to the management of hot gas produced
from a single burner, for space heating, wherein a portion of this
hot gas is used for preheating and/or component operation of a fuel
cell. While the present disclosure can be implement in many
different forms, it will be described herein as a self-powered
breathable air heating system that re-circulates breathable air
flow, and contains all necessary major and minor subsystems for
startup operation and shut down that derives their respective
electrical power requirements from a fuel cell generator. The
thermal energy created by the fuel-fired burner is in excess of the
requirements of the fuel cell generator, and is largely used for
re-circulated airflow space heating. The fuel cell generator is
configured to support the safe and efficient operation of the
self-powered heater used for soft and hard wall space heating.
[0053] Further, by redirecting a portion of the hot gas flow
created by a burner, various types of hot gases, such as rich or
lean, having varying temperatures and humidity can be created.
These hot gases can be used for fuel cell stack pre-heating,
component heating, such as reformers, or to provide the stack or
fuel cell element with fuel delivery.
[0054] The present disclosure is not limited to a co-generation
device, even though the nature of all heated components housed
within a common enclosure would qualify the integrated package as
being co-generated. The term co-generation includes combined heat
and power (CHP), MicroCHP, a distributed energy resource and
tri-generation (a system that produces electricity, heat and cold
via a fuel cell).
[0055] With reference now to FIG. 3, a space heater according to
one aspect of the present disclosure is schematically illustrated.
The heater comprises an air inlet fan (not shown), a burner 111, a
fuel cell assembly 200 and a heat exchanger. The burner is
positioned downstream of the air inlet fan and produces a hot gas.
The heat exchanger is positioned downstream of the burner and is
operatively connected therewith for receiving at least some of the
hot gas. The burner and the heat exchanger provide primary space
heating, which can be regulated by the adjustment of the burner
combustion process by varying the air fuel ratio. This, in turn,
changes the temperature of the hot gas produced by the burner. The
fuel cell assembly 200 provides electrical energy to operate the
space heater. The fuel cell assembly is also operatively connected
to the burner 111 for receiving at least some of the hot gas. The
fuel cell assembly 200 includes a housing 210 for accommodating a
fuel cell component 240 and a heat compartment 241 (i.e., a hot
zone) for management of combustion hot gasses to heat the fuel cell
component. An enclosure 220 accommodates the burner 111, heat
exchanger 112 and fuel cell assembly 200. The air inlet fan creates
an air flow through the enclosure 220.
[0056] The schematic block of the fuel cell component 240 is used
to depict the various components required for fuel cell operation.
The schematic block for the heat compartment 241 depicts an area
that can be used to manage, distribute and house different
components that need heating. By having a heat source produced by a
single burner 111, with a fire rate many times greater than what a
fuel cell would require when used for operational electrical power,
one can appreciate the freedom of component layout and hot zones
that can be thermally detached from one another, thus providing
optimum temperature control while still producing heater related
BTU output. Another aspect of the disclosure is communicating with
a hot gas BTU content many times greater than previously used to
preheat the fuel cell component 240. This allows for very fast
preheating of the fuel cell component. Testing has shown preheat
temperatures of the heat compartment 241 with the fuel cell
component 240 to both 700 and 1000 degrees Celsius in under 10
minutes while maintaining proper atmosphere around fuel cell
component.
[0057] The heat compartment 241 can be controllable both in
temperature and atmosphere for fuel cell component operation. The
heat compartment can be of a variety of designs but mainly is a
high temperature furnace consisting of basic components such as
heat shields, external stainless steel foil, or internal ceramic
type insulation selected for the specific fuel cell component
temperature and atmosphere requirement. The shape of the heat
compartment 241 can be form fitting for the fuel cell component
that it houses. A basic shape can be a rectangular or cylindrical
form designed to be modular for ease of removal and repair.
[0058] The fuel cell assembly is connected to the burner 111 via
hot gas conduit 117a, and is connected to the heat exchanger 112
via hot gas conduit 117b. The hot gas conduits depict the transfer
of hot gas from one component to another. It should be appreciated
that a direct coupling of the components is also contemplated. The
fuel cell component 240 is separated from the heat compartment by a
mantel 242. A predetermined percentage of thermal energy is
bypassed from the main hot gas air stream by radiation using the
mantel 242. The remainder of burner hot gas is expelled through
exhaust pipe 113 after passing through the air-to-air heat
exchanger 112. The temperature of the fuel cell component can be
further regulated by the adjustment of the burner combustion
process by varying the air fuel ratio, which, in turn, changes the
temperature of the hot gas.
[0059] The mantel 242 can be a solid plate mantel (see FIG. 13)
such that the fuel cell component 240 is heated via radiant heat
within the heat compartment 241. Alternatively, the mantel 242 can
be a perforated plate mantel to allow radiation and convection flow
through heat compartment 241 (see FIG. 14). The fuel cell component
is heated by a combination of radiant heat and hot gas flow using a
perforated plate mantel.
[0060] With reference to FIG. 4, a hot gas conduit 243 is connected
to the fuel cell assembly 200 and expels the hot gas flow to
atmosphere. A variable flow restrictor 244 is connected to the hot
gas conduit 243 and communicates with the fuel cell component 240.
The variable flow restrictor can regulate gross BTU by shutting off
or throttling the amount of hot gas flow through the heat
compartment 241, mantel 242 and fuel cell component 240. By opening
and closing the variable flow restrictor 244, a bypass flow of hot
gas and temperature is regulated by increasing or decreasing the
hot gas flow through the fuel heat compartment 241, the fuel cell
component 240, the hot gas conduit 243, the variable flow
restrictor 244 and then to atmosphere via hot gas conduit 245.
[0061] A benefit of continuous heating of the fuel cell component
240 can be realized by reduction or elimination of conventional
fuel cell component insulation. Insulation is used for efficiency
and to provide heat shielding from other components. This reduction
or elimination of insulation saves cost and reduces weight thereby
making the fuel cell component 240 less complicated to manufacture
and maintain in the field. All fuel cell component rejected heat is
captured within the airflow generated by the fan 114 (see FIG. 2)
and added to the cooler airflow prior to the heat exchanger 112.
The heat output of the fuel cell component 240 and heat exchanger
112 is the total heated airflow output. Thus, the heat conversion
efficiency of the fuel cell component 240 can be low because the
heat loss is re-introduced into the breathable air stream. Another
advantage of using the heat exchanger 112 hot gas flow is by use of
the mantel 242. Temperatures of 700 to 1000 degrees Celsius can be
easily obtained and transferred through use of various mantel
shapes from this pass through high velocity hot gas flow. By using
the correct shape of the mantel, various temperatures can be
created from the same temperature and BTU pass through heat
exchanger 112 intended hot gas flow. By changing the shape of the
heat compartment 241 and the mantel 242, hot gas velocities and
impingement can be controlled to various temperatures. After the
heat compartment 241 reaches near temperature equilibrium with the
mantel 242, less BTUs are transferred and are retained in the hot
gas flow to the heat exchanger 112.
[0062] With reference to FIG. 5, a space heater according to
another aspect of the present disclosure is schematically
illustrated. The space heater of FIG. 5 is similar to the space
heater of FIG. 4 except that the fuel cell assembly 200 is located
downstream of both the burner 111 and the heat exchanger 112. An
enclosure (not shown) accommodates the burner, heat exchanger and
fuel cell assembly. An air inlet fan (not shown) creates an air
flow through the enclosure. The hot gas temperature in the hot gas
conduit 117b is reduced by the heat exchanger. Therefore, the
temperature required for the operation of the fuel cell component
240 is less than combustion temperature. Particularly, hot gas
having temperatures less than 1,000.degree. F. flows from the heat
exchanger 112, through the hot gas conduit 117b, to the heat
compartment 241 and exits via the exhaust pipe 113. Again, the
variable flow restrictor 244 can regulate hot gas flow through the
hot gas conduit 243.
[0063] Referring now to FIG. 6, a space heater according to yet
another aspect of the present disclosure is schematically
illustrated. Similar to the previous embodiments, the heater
includes a burner 111, a fuel cell assembly 200 and a heat
exchanger 112. In this embodiment, the fuel cell assembly is
downstream of the burner and upstream of the heat exchanger. An
enclosure (not shown) accommodates the burner, heat exchanger and
fuel cell assembly. An air inlet fan (not shown) creates an air
flow through the enclosure. Hot gasses from the burner flows
through a hot gas conduit 117 to both the heat exchanger and the
heat compartment 241 of the fuel cell assembly. A separate hot gas
conduit 117c is connected to the hot gas conduit 117 and the heat
compartment 241 for directing hot gas into the heat compartment.
Again, hot gas flowing through the fuel cell assembly is regulated
by the variable flow restrictor 244 and exits through the hot gas
conduit 245.
[0064] The single hot gas conduit 117c can attach to the heat
compartment 241 or to a manifold (not shown) to supply more than
one hot gas source of heat or combustion gases to multiple
components as needed. The regulation of the flow of gas is provided
by variable flow restrictor 244. The pressure needed to provide hot
gas flow through hot gas conduit 117c and through the various
components of heat compartment 241 is regulated by the internal
design of the heat exchanger 112 and or at exhaust pipe 113 by the
addition of a baffle or restrictor plate (see FIG. 14).
[0065] As shown in FIG. 7, a fuel cell assembly includes energy
conversion units or fuel cells 350, which can be located within the
heat compartment 241. In the depicted embodiment, the energy
conversion units are ceramic rods, which are only an example of
components that can be heat managed. It should be appreciated that
alternative components are also contemplated. As required, the hot
gas conduit 117c supplies hot gas flow to the heat compartment 241.
The mantel 242 disperses the hot gas flow evenly or to specific
areas of the energy conversion units 350. The energy conversion
units 350 are preheated and kept at operating temperature by
regulation of the flow restrictor 244.
[0066] Alternatively, as shown in FIG. 8, a fuel cell assembly
includes a reformer 351, which can be located within the heat
compartment 241. As is well known, reformers use heat and catalysts
to "crack" hydrocarbons and release the hydrogen they contain. A
reformer produces a mixture of gases that must then be purified in
order to produce hydrogen pure enough for use in a polymer exchange
membrane (PEM) fuel cell (see FIG. 9). The PEM fuel cell has a high
power density and a relatively low operating temperature (ranging
from 60 to 80 degrees Celsius, or 140 to 176 degrees Fahrenheit).
The low operating temperature means that it doesn't take very long
for the fuel cell to warm up and begin generating electricity.
Similar to the fuel cells 350, the reformer can be pre-heated and,
as required, kept at operational temperature during extreme cold
ambient temperatures.
[0067] With reference to FIG. 9, the PEM fuel cell assembly
includes a fuel cell processor 352, which can be located within the
heat compartment 241. The fuel cell processor 352 is supplied with
fuel 460 through a fuel line 461. The fuel can be alcohol (e.g.,
methanol or ethanol) or hydrocarbons (e.g., gasoline diesel
kerosene), which can serve as the source of hydrogen for the fuel
cell. The fuel processor 352 uses steam for the reformation
process. Water 464 is supplied by a water line 465 and heat is
supplied by the hot gas conduit 117c. The heat is regulated by the
variable flow restrictor 244. Reformate can be supplied to the heat
compartment 241 by a reformate line. Spent hot gas and fuel
processor effluent exit through the hot gas conduit 245.
[0068] A solid oxide fuel cell (SOFC) is schematically illustrated
in FIG. 10. This type of fuel cell operates at very high
temperatures (between 700 and 1,000 degrees Celsius). The SOFC fuel
cell generally uses direct diesel or kerosene fuel gas for
operation.
[0069] In use, the energy conversion units 350, which are housed
within the heat compartment 241, are heated to a predetermined
operating temperature by opening the flow restrictor 244 and
establishing gas flow through the hot gas conduit 117c. When the
energy conversion units 350 have reached the operating temperature,
the variable flow restrictor 244 is closed. The fuel line 461
supplies a fuel injector 462 to charge the heat compartment 241
with the proper air fuel ratio for operation. If cooling or steam
is needed for the operation, the water line 465 supplies water to
an injector 466. During operation, the variable flow restrictor 244
can be partially opened to provide hot gas or purging airflow to
expel energy conversion units effluent through the hot gas conduit
245.
[0070] With reference to FIG. 11, a space heater according to yet
another aspect of the present disclosure is schematically
illustrated. Similar to the previous embodiments, the heater
includes a burner 111, at least one fuel cell assembly and a heat
exchanger 112. An enclosure (not shown) accommodates the burner,
the heat exchanger and the at least one fuel cell assembly. An air
inlet fan (not shown) creates an air flow through the enclosure.
Hot gasses from the burner flows through the hot gas conduit 117 to
both the heat exchanger and the at least one fuel cell assembly via
a separate hot gas conduit 117c. Particularly, the hot gas flowing
through the hot gas conduit 117c is split between a first fuel cell
assembly and a second fuel cell assembly. The first fuel cell
assembly is similar in structure to the fuel cell assembly of FIG.
7 and includes the fuel cell component 240. The second fuel cell
assembly is similar in structure to the fuel cell assembly of FIG.
8 and includes a reformer 351. Hot gas flowing through the first
fuel cell assembly is regulated by variable flow restrictor 244 and
exits through the hot gas conduit 245. Hot gas flowing through the
second fuel cell assembly is regulated by variable flow restrictor
244b and exits through the hot gas conduit 245b.
[0071] In the embodiment of FIG. 11, the spent by-pass hot gases
and effluent from the first and second fuel cell assemblies
required for fuel cell operation are re-introduced into the burner
111 by connecting both hot gas conduits 245 and 245b to a blower
119. The blower directs the spent hot gas and fuel cell effluent
into the burner 111 via a pressurized combustion waste line
120.
[0072] Alternatively, as shown in FIG. 12, the blower 119 can
direct the spent hot gas and fuel cell effluent into the heat
exchanger 112 via the pressurized combustion waste line 120.
Depending upon the configuration of heater components, the blower
119 provides the overpressure required to inject the effluent into
the heat exchanger 112. However, a blower located in a hot
combustion gas flow generally has to be protected from condensation
and corrosive properties of the fuel cell effluent. A pressure
differential can be created by positioning a hot gas restrictor 122
between the blower 111 and the heat exchanger 112 thereby providing
a lower pressure within the heat exchanger 112. In some instances,
the hot gas restrictor will eliminate the need for the blower
119.
[0073] As is evident from the foregoing, the present disclosure
generally relates to a self-powered heater for providing primary
heat for use in soft and hard wall shelters. The self-powered
heater includes a burner, a heat exchanger and at least one fuel
cell assembly. The burner fire rate or fuel consumption far exceeds
the fuel rate needed by the fuel cell assembly. The addition of the
fuel cell assembly is to provide electrical energy to operate the
heater. Though rejected heat and waste effluent of the fuel cell
assembly can be captured and added to the thermal output energy of
the heater, the percentage of heat reclaimed in comparison to the
heat created by the burner and heat exchanger is small.
Cogeneration of the fuel cell assembly is a thermodynamically
efficient use of fuel. The efficient use of fuel in the
self-powered heater is derived by the heat exchanger and combustion
efficiency.
[0074] A portion of the burner hot gas flow can be used to heat
various types of fuel cell components. The bypassed hot gas is used
for heating a hot zone which is controllable both in temperature
and atmosphere for fuel cell component operation. The heat output
(used for space heating) exceeds the heat (energy input) required
for power generation. The burner and heat exchanger provide primary
space heating by generating a heated breathable re-circulated
airflow. The heater operates from fuel cell generated electricity
and is started or sustained by hot gas communication with the fuel
fired burner combustion gases. The fuel-fired burner, the fuel cell
assembly and the heat exchanger is integrated such that the fuel
cell assembly is continuously in communication with the burner hot
gas flow before the heat exchanger. Fuel fired burner hot gas flow
regulation through the fuel cell assembly can modulates the hot gas
flow through the fuel cell assembly. The burner hot gas flow can be
lower in temperature by using the hot gas flow after the heat
exchanger.
[0075] Components common to the operation of the self-powered
heaters described above (balance of plant) can be used to supply
the fuel cell assembly with basic operating functions which
significantly improve the utility of the fuel cell assembly.
Various types of combustion processes and fuel air ratios can be
created using existing burner atomization processes such as hot
vaporizer, air atomized, spinner atomizer, and high-pressure nozzle
type. The atomization process is down selected upon the BTU output,
hours of operation before repair, fuel types, altitudes, cold
temperature starting and burner assembly cost. A fuel pump for the
heater can be a pulse pump, diaphragm or gear depending on the
pressure required for atomization. A variable speed combustion
blower can provide sufficient burner and heat exchanger
backpressure during operation. A custom controller designed for low
EMI and extreme cold operation can operate the self-powered heater.
Altitude air fuel compensation, tent thermostat fire rate turn
down, pre purge with system component checking and wire harness
checks are standard designs of today's self-powered heater. These
components can also supply the necessary airflows, fuel sources and
electronic control of the fuel cell subcomponents. In addition to
using common components for fuel cell operation, the burner air
fuel ratio can also be changed to provide a rich or lean mixture
for fuel cell component operation. These air to fuel ratios can be
programmed into the controller logic to provide custom combustion
hot gases during operation.
[0076] The ability to shut off the burner or to have the burner at
a very low output is also possible. Particularly, the burner is
started to create hot gas to provide fuel cell component heating.
By-pass heat is provided to the fuel cell component. The burner can
then be throttled down via regulation of the variable flow
restrictor to provide only the necessary heat for operation of the
fuel cell component.
[0077] By providing a single burner heat source much larger in
thermal output than is required for fuel cell operation, sufficient
temperatures and hot gas flows for space heating and re-burning of
fuel cell gases is provided. This allows the heater to be smaller
in size and less complicated. The heater will have increased
reliability and a reduced cost while producing space heating
simultaneously.
[0078] It should be appreciated that the schematic diagrams
described above generally omit excessive component detail (for
example, electronic controls such as micro processors, fuel
delivery loops, water storage and separators, pumps, compressors,
pressure controls, starting battery, external fuel supply,
temperature and humidity sensors, and the like) in order to focus
on the hot gas integration to fuel cell generator components of the
self-powered heater. A provision of these necessary items is
required for operation of the system, but is common to a
thermoelectric self-powered heater and is not required for
understanding the disclosure.
[0079] The present disclosure is not limited to any one type of
fuel cell technology and primary fuel type. Current self-powered
heaters use fielded fuels such as diesel, kerosene, JP-8, DF-A, and
specific heating applications my require operation on natural gas,
propane, bio-fuels and gasoline as an example.
[0080] Any type of fuel cell assembly that requires heat can
implement the teaching of the present disclosure, such as Polymer
Electrolyte Membrane (PEM), Phosphoric Acid, (PAFC), Direct
Methanol Fuel Cell (DMFC), Alkaline Fuel Cell (AFC), Molten
Carbonate Fuel Cell (MCFC), Solid Oxide Fuel Cell (SOFC), and
Regenerative (Reversible) Fuel Cells.
[0081] The present disclosure has been described with reference to
several embodiments. Obviously, modifications and alterations will
occur to others upon reading and understanding the preceding
detailed description. It is intended that the present disclosure be
construed as including all such modifications and alterations
insofar as they come within the scope of the appended claims or the
equivalents thereof.
* * * * *