U.S. patent application number 14/849820 was filed with the patent office on 2016-01-07 for method for dispensing a gas.
The applicant listed for this patent is Air Products and Chemicals, Inc.. Invention is credited to Joseph Perry Cohen, David John Farese, Nicholas Francis Mittica.
Application Number | 20160003415 14/849820 |
Document ID | / |
Family ID | 48740915 |
Filed Date | 2016-01-07 |
United States Patent
Application |
20160003415 |
Kind Code |
A1 |
Cohen; Joseph Perry ; et
al. |
January 7, 2016 |
Method for Dispensing a Gas
Abstract
A method for dispensing gas within a target temperature range
wherein the gas exchanges heat with multiple thermal capacitors to
cool the gas.
Inventors: |
Cohen; Joseph Perry;
(Bethlehem, PA) ; Farese; David John;
(Riegelsville, PA) ; Mittica; Nicholas Francis;
(Zionsville, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Air Products and Chemicals, Inc. |
Allentown |
PA |
US |
|
|
Family ID: |
48740915 |
Appl. No.: |
14/849820 |
Filed: |
September 10, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13648622 |
Oct 10, 2012 |
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14849820 |
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13542761 |
Jul 6, 2012 |
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13648622 |
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Current U.S.
Class: |
141/4 |
Current CPC
Class: |
F17C 2270/0171 20130101;
F17C 2265/065 20130101; F17C 2250/0443 20130101; F17C 2223/0123
20130101; F17C 2260/023 20130101; Y02E 60/321 20130101; F17C
2223/035 20130101; F17C 2227/0388 20130101; F17C 2227/047 20130101;
F17C 2225/036 20130101; F17C 2270/0178 20130101; F17C 2225/0115
20130101; F17C 2221/012 20130101; F17C 2225/0123 20130101; F17C
2227/0323 20130101; F17C 2227/0355 20130101; F17C 2227/039
20130101; Y02E 60/32 20130101; F17C 5/06 20130101; F17C 2270/0168
20130101; F17C 2221/033 20130101; F17C 2223/036 20130101; F17C
2270/0176 20130101; F17C 2225/035 20130101; F17C 2250/0439
20130101; F17C 2223/0115 20130101 |
International
Class: |
F17C 5/06 20060101
F17C005/06 |
Claims
1. A method for dispensing gas, the method comprising: dispensing a
gas from a gas source at an initial temperature into a receiving
vessel at a dispensing temperature, the dispensing temperate being
within a first target temperature range and being lower than the
initial temperature; cooling the gas from the initial temperature
to the dispensing temperature during the dispensing step via heat
exchange with a plurality of thermal capacitors arranged in series;
circulating a refrigerant to each of the plurality of thermal
capacitors using a refrigeration unit; and performing the
circulating step for each of the plurality of thermal capacitors as
a function of a measured temperature of each of the plurality of
thermal capacitors and independently of whether the cooling step is
being performed.
2. The method of claim 1, further comprising: repeating the
dispensing step without performing the circulating step, wherein
the dispensing step comprises dispensing at least 3 kg of the
gas.
3. The method of claim 1, further comprising: providing each of the
plurality of thermal capacitors with a sufficient thermal mass to
enable a dispensing step in which at least 5 kg of gas is dispensed
without performing the circulating step.
4. The method of claim 1, further comprising: performing at least a
portion of the circulating step when the dispensing step is not
being performed.
5. The method of claim 1, wherein the cooling step comprises
cooling the gas via heat exchange with at least two of the
plurality of thermal capacitors and heating the gas via heat
exchange with a last of the plurality of thermal capacitors.
6. A method for dispensing a gas, the method comprising:
withdrawing a first quantity of the gas from a gas source, the
first quantity of gas having an initial temperature; cooling the
first quantity of gas via heat exchange with a first thermal
capacitor wherein the first thermal capacitor has a temperature
lower than the minimum temperature of a first target temperature
range when the first quantity of gas is initially cooled by the
first thermal capacitor; cooling the first quantity of gas via heat
exchange with a second thermal capacitor wherein the second thermal
capacitor has a temperature lower than the minimum temperature of
the first target temperature range when the first quantity of gas
is initially cooled by the second thermal capacitor, wherein the
first quantity of gas is cooled via heat exchange with the second
thermal capacitor after being cooled via heat exchange with the
first thermal capacitor; heating the first quantity of gas via heat
exchange with a third thermal capacitor wherein the third thermal
capacitor has a temperature within the first target temperature
range, wherein the first quantity of gas exchanges heat with the
third thermal capacitor after being cooled via heat exchange with
the second thermal capacitor; and introducing the first quantity of
gas from the third thermal capacitor into a first receiving vessel,
the first quantity of gas thereby having a dispensing temperature
within the first target temperature range, wherein the dispensing
temperature is less than the initial temperature.
7. The method of claim 6 further comprising: withdrawing a second
quantity of the gas from the gas source; cooling the second
quantity of gas via heat exchange with the first thermal capacitor;
cooling the second quantity of gas via heat exchange with the
second thermal capacitor, wherein the second quantity of gas is
cooled via heat exchange with the second thermal capacitor after
being cooled via heat exchange with the first thermal capacitor;
heating or cooling the second quantity of gas via heat exchange
with the third thermal capacitor wherein the third thermal
capacitor has a temperature within the first target temperature
range, wherein the second quantity of gas exchanges heat with the
third thermal capacitor after being cooled via heat exchange with
the second thermal capacitor; and introducing the second quantity
of gas from the third thermal capacitor into a second receiving
vessel, the second quantity of gas thereby having a dispensing
temperature within the first target temperature range.
8. The method of claim 6 further comprising: cooling the first
thermal capacitor, the second thermal capacitor, and the third
thermal capacitor via heat exchange with a refrigerant, wherein the
refrigerant is cycled in a refrigeration cycle.
9. The method of claim 8 wherein the flow rate of the refrigerant
to each of the first thermal capacitor, the second thermal
capacitor, and the third thermal capacitor is independently
controlled.
10. The method of claim 6 further comprising: cooling the first
thermal capacitor and the second thermal capacitor via heat
exchange with a refrigerant, wherein the refrigerant is cycled in a
refrigeration cycle; and cooling the third thermal capacitor via
heat exchange with a second refrigerant, wherein the second
refrigerant is cycled in a second refrigeration cycle.
11. The method of claim 6 further comprising: withdrawing a third
quantity of the gas from the gas source; cooling the third quantity
of gas via heat exchange with the first thermal capacitor; cooling
the third quantity of gas via heat exchange with the second thermal
capacitor, wherein the third quantity of gas is cooled via heat
exchange with the second thermal capacitor after being cooled via
heat exchange with the first thermal capacitor; heating or cooling
the third quantity of gas via heat exchange with a fourth thermal
capacitor wherein the fourth thermal capacitor has a temperature
within a second target temperature range, wherein the second target
temperature range is different than the first target temperature
range, and wherein the third quantity of gas exchanges heat with
the fourth thermal capacitor after being cooled via heat exchange
with the second thermal capacitor; and introducing the third
quantity of gas from the fourth thermal capacitor into a third
receiving vessel, the third quantity of gas thereby having a
dispensing temperature within the second target temperature
range.
12. The method of claim 11 further comprising: measuring an ambient
temperature representative of conditions surrounding a fourth
receiving vessel; withdrawing a fourth quantity of the gas from the
gas source; cooling the fourth quantity of gas via heat exchange
with the first thermal capacitor; cooling the fourth quantity of
gas via heat exchange with the second thermal capacitor, wherein
the fourth quantity of gas is cooled via heat exchange with the
second thermal capacitor after being cooled via heat exchange with
the first thermal capacitor; heating or cooling the fourth quantity
of gas via heat exchange with one of the third thermal capacitor
and the fourth thermal capacitor, the third thermal capacitor
having its temperature within the first temperature range, the
fourth thermal capacitor having its temperature within the second
temperature range, the selection of heating or cooling the fourth
quantity of gas via heat exchange with the third thermal capacitor
or the fourth thermal capacitor dependent upon the measured ambient
temperature surrounding the fourth receiving vessel; and
introducing the fourth quantity of gas from the third thermal
capacitor or from the fourth thermal capacitor into the fourth
receiving vessel, the fourth quantity of gas thereby having a
dispensing temperature within the first target temperature range
when the fourth quantity of gas exchanges heat with the third
thermal capacitor or having a dispensing temperature within the
second target temperature range when the fourth quantity of gas
exchanges heat with the fourth thermal capacitor.
13. The method of claim 6 wherein at least one of the first thermal
capacitor, the second thermal capacitor, and the third thermal
capacitor comprises a metal.
14. The method of claim 13 wherein the metal is aluminum.
15. The method of claim 6 wherein at least one of the first thermal
capacitor, the second thermal capacitor, and the third thermal
capacitor comprises a liquid.
16. The method of claim 15 wherein the liquid is a liquid
hydrocarbon.
17. The method of claim 16 wherein the liquid hydrocarbon is a C10
to C13 iso-alkane.
18. The method of claim 6 further comprising: withdrawing a fifth
quantity of the gas from the gas source; and introducing the fifth
quantity of gas from the gas source into a fifth receiving vessel
without cooling the fifth quantity of gas between withdrawing the
fifth quantity of gas from the gas source and introducing the fifth
quantity of gas into the fifth receiving vessel.
19. The method of claim 6 further comprising: measuring an ambient
temperature representative of conditions surrounding the first
receiving vessel prior to withdrawing the first quantity of gas
from the gas source; and setting the first target temperature range
dependent upon the measured ambient temperature prior to
withdrawing the first quantity of gas from the gas source.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S.
application Ser. No. 13/648,622, filed Oct. 10, 2012, which is a
continuation-in-part of U.S. application Ser. No. 13/542,761, filed
Jul. 6, 2012, the specification and claims of each being
incorporated by reference and made a part of this application.
BACKGROUND
[0002] The present invention is particularly suited for dispensing
hydrogen to vehicles that use hydrogen as a fuel.
[0003] Industry desires to dispense hydrogen gas that has been
cooled from ambient temperature down to a temperature within a
narrow temperature range during the dispensing event. The
refrigeration load during the dispensing event is much larger than
the average refrigeration requirement.
[0004] In an example dispensing protocol, there is a need to
provide hydrogen gas at a temperature between -33.degree. C. and
-40.degree. C. The hydrogen gas must be dispensed within this
target temperature range for multiple sequential dispensing events.
The dispensing station and method must therefore be capable of
providing sufficient cooling for each of the multiple sequential
dispensing events within the target temperature range for
quantities of gas that will vary both in size, typically 3 to 10
kg, and in flow rate, typically 0.25 to 3.6 kg/min.
BRIEF SUMMARY
[0005] The present invention relates to a method for dispensing a
gas.
[0006] There are several aspects of the method as outlined
below.
[0007] Aspect 1. A method comprising: [0008] withdrawing a first
quantity of the gas from a gas source; [0009] cooling the first
quantity of gas via heat exchange with a first thermal capacitor
wherein the first thermal capacitor has a temperature lower than
the minimum temperature of a first target temperature range when
the first quantity of gas is initially cooled by the first thermal
capacitor; [0010] cooling the first quantity of gas via heat
exchange with a second thermal capacitor wherein the second thermal
capacitor has a temperature lower than the minimum temperature of
the first target temperature range when the first quantity of gas
is initially cooled by the second thermal capacitor, wherein the
first quantity of gas is cooled via heat exchange with the second
thermal capacitor after being cooled via heat exchange with the
first thermal capacitor; [0011] heating or cooling the first
quantity of gas via heat exchange with a third thermal capacitor
wherein the third thermal capacitor has a temperature within the
first target temperature range, wherein the first quantity of gas
exchanges heat with the third thermal capacitor after being cooled
via heat exchange with the second thermal capacitor; and [0012]
introducing the first quantity of gas from the third thermal
capacitor into a first receiving vessel, the first quantity of gas
thereby having a dispensing temperature within the first target
temperature range.
[0013] Aspect 2. The method of aspect 1 wherein the first quantity
of gas is heated via heat exchange with the third thermal
capacitor.
[0014] Aspect 3. The method of aspect 1 or aspect 2 further
comprising: [0015] withdrawing a second quantity of the gas from
the gas source; [0016] cooling the second quantity of gas via heat
exchange with the first thermal capacitor; [0017] cooling the
second quantity of gas via heat exchange with the second thermal
capacitor, wherein the second quantity of gas is cooled via heat
exchange with the second thermal capacitor after being cooled via
heat exchange with the first thermal capacitor; [0018] heating or
cooling the second quantity of gas via heat exchange with the third
thermal capacitor wherein the third thermal capacitor has a
temperature within the first target temperature range, wherein the
second quantity of gas exchanges heat with the third thermal
capacitor after being cooled via heat exchange with the second
thermal capacitor; and [0019] introducing the second quantity of
gas from the third thermal capacitor into a second receiving
vessel, the second quantity of gas thereby having a dispensing
temperature within the first target temperature range.
[0020] Aspect 4. The method of any one of aspects 1 to 3 further
comprising: [0021] cooling the first thermal capacitor, the second
thermal capacitor, and the third thermal capacitor via heat
exchange with a refrigerant, wherein the refrigerant is cycled in a
refrigeration cycle.
[0022] Aspect 5. The method of aspect 4 wherein the flow rate of
the refrigerant to each of the first thermal capacitor, the second
thermal capacitor, and the third thermal capacitor is independently
controlled.
[0023] Aspect 6. The method of any one of aspects 1 to 3 further
comprising: [0024] cooling the first thermal capacitor and the
second thermal capacitor via heat exchange with a refrigerant,
wherein the refrigerant is cycled in a refrigeration cycle; and
[0025] cooling the third thermal capacitor via heat exchange with a
second refrigerant, wherein the second refrigerant is cycled in a
second refrigeration cycle.
[0026] Aspect 7. The method of any one of aspects 4 to 6 wherein
the refrigerant is selected from the group consisting of R22,
R404A, and R507.
[0027] Aspect 8. The method of aspect 6 wherein the second
refrigerant is selected from the group consisting of R22, R404A,
and R507.
[0028] Aspect 9. The method of any one of aspects 1 to 8 further
comprising: [0029] withdrawing a third quantity of the gas from the
gas source; [0030] cooling the third quantity of gas via heat
exchange with the first thermal capacitor; [0031] cooling the third
quantity of gas via heat exchange with the second thermal
capacitor, wherein the third quantity of gas is cooled via heat
exchange with the second thermal capacitor after being cooled via
heat exchange with the first thermal capacitor; [0032] heating or
cooling the third quantity of gas via heat exchange with a fourth
thermal capacitor wherein the fourth thermal capacitor has a
temperature within a second target temperature range, wherein the
second target temperature range is different than the first target
temperature range, and wherein the third quantity of gas exchanges
heat with the fourth thermal capacitor after being cooled via heat
exchange with the second thermal capacitor; and [0033] introducing
the third quantity of gas from the fourth thermal capacitor into a
third receiving vessel, the third quantity of gas thereby having a
dispensing temperature within the second target temperature
range.
[0034] Aspect 10. The method of aspect 9 further comprising: [0035]
measuring an ambient temperature representative of conditions
surrounding a fourth receiving vessel; [0036] withdrawing a fourth
quantity of the gas from the gas source; [0037] cooling the fourth
quantity of gas via heat exchange with the first thermal capacitor;
[0038] cooling the fourth quantity of gas via heat exchange with
the second thermal capacitor, wherein the fourth quantity of gas is
cooled via heat exchange with the second thermal capacitor after
being cooled via heat exchange with the first thermal capacitor;
[0039] heating or cooling the fourth quantity of gas via heat
exchange with one of the third thermal capacitor and the fourth
thermal capacitor, the third thermal capacitor having its
temperature within the first temperature range, the fourth thermal
capacitor having its temperature within the second temperature
range, the selection of heating or cooling the fourth quantity of
gas via heat exchange with the third thermal capacitor or the
fourth thermal capacitor dependent upon the measured ambient
temperature surrounding the fourth receiving vessel; and [0040]
introducing the fourth quantity of gas from the third thermal
capacitor or from the fourth thermal capacitor into the fourth
receiving vessel, the fourth quantity of gas thereby having a
dispensing temperature within the first target temperature range
when the fourth quantity of gas exchanges heat with the third
thermal capacitor or having a dispensing temperature within the
second target temperature range when the fourth quantity of gas
exchanges heat with the fourth thermal capacitor.
[0041] Aspect 11. The method of any one of aspects 1 to 10 wherein
at least one of the first thermal capacitor, the second thermal
capacitor, and the third thermal capacitor comprises a metal.
[0042] Aspect 12. The method of aspect 11 wherein the metal is
aluminum.
[0043] Aspect 13. The method of any one of aspects 1 to 9 wherein
at least one of the first thermal capacitor, the second thermal
capacitor, and the third thermal capacitor comprises a liquid.
[0044] Aspect 14. The method of aspect 13 wherein the liquid is a
liquid hydrocarbon.
[0045] Aspect 15. The method of aspect 14 wherein the liquid
hydrocarbon is a C10-C13 iso-alkane.
[0046] Aspect 16. The method of any one of aspects 1 to 15 further
comprising: [0047] withdrawing a fifth quantity of the gas from the
gas source; and [0048] introducing the fifth quantity of gas from
the gas source into a fifth receiving vessel without cooling the
fifth quantity of gas between withdrawing the fifth quantity of gas
from the gas source and introducing the fifth quantity of gas into
the fifth receiving vessel.
[0049] Aspect 17. The method of any one of the preceding aspects
further comprising: [0050] measuring an ambient temperature
representative of conditions surrounding the first receiving vessel
prior to withdrawing the first quantity of gas from the gas source;
and [0051] setting the first target temperature range dependent
upon the measured ambient temperature prior to withdrawing the
first quantity of gas from the gas source.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0052] The sole FIGURE is a schematic of a system suitable for
carrying out the method.
DETAILED DESCRIPTION
[0053] The articles "a" and "an" as used herein mean one or more
when applied to any feature in embodiments of the present invention
described in the specification and claims. The use of "a" and "an"
does not limit the meaning to a single feature unless such a limit
is specifically stated. The article "the" preceding singular or
plural nouns or noun phrases denotes a particular specified feature
or particular specified features and may have a singular or plural
connotation depending upon the context in which it is used. The
adjective "any" means one, some, or all indiscriminately of
whatever quantity. The term "and/or" placed between a first entity
and a second entity means one of (1) the first entity, (2) the
second entity, and (3) the first entity and the second entity. The
term "and/or" placed between the last two entities of a list of 3
or more entities means at least one of the entities in the
list.
[0054] The phrase "at least a portion" means "a portion or all."
The at least a portion of a stream may have the same composition as
the stream from which it is derived. The at least a portion of a
stream may include specific components of the stream from which it
is derived.
[0055] As used herein, "first," "second," "third," etc. are used to
distinguish from among a plurality of steps and/or features, and is
not indicative of the relative position in time and/or space.
[0056] Compressed natural gas (CNG) and hydrogen are the typical
components dispensed from storage systems, which are usually
installed outdoors and are therefore subjected to wide ranges of
ambient temperatures. Ambient temperatures are well above the
critical temperature of hydrogen (-240.degree. C. (-400.degree.
F.)) and methane (-83.degree. C. (-117.degree. F.)), so that these
components typically are stored and dispensed as supercritical
fluids rather than gases according to strict thermodynamic
definitions. However, the terms "gas" and "compressed gas" are
usually used in the art as generic terms for both gases and
supercritical fluids. In the present disclosure, the terms "gas"
and "compressed gas" may be used interchangeably and are meant to
include elements and compounds in both thermodynamic states of gas
and supercritical fluid. The generic term "fluid" as used herein
includes both thermodynamic states of gas and supercritical
fluid.
[0057] A gas dispensing system is defined as a pressurized gas
storage and supply system for providing pressurized gas to a
portable receiving tank or vessel. The gas dispensing system
includes a connector to couple with the receiving vessel for gas
transfer and an appropriate safety interlock system to ensure safe
operation during the filling step. The receiving tank or vessel
typically is part of a vehicle such as a car, truck, bus, or
forklift.
[0058] The present invention relates to a method for dispensing a
gas, for example H.sub.2, at a temperature within one or more
target temperature ranges. Target temperature ranges may be preset
by the device or selected by a user or operator. The target
temperature ranges may be dependent on a measured ambient
temperature. The target temperature ranges may be dependent on a
measured temperature of the receiving vessel and/or gas in the
receiving vessel. Each target temperature range has its prescribed
minimum temperature and maximum temperature.
[0059] The method will be described with reference to the figure
illustrating a suitable apparatus for carrying out the method.
[0060] The apparatus comprises a gas source 7, at least three
thermal capacitors 101, 103, and 107, a compressor 157, a heat
exchanger (condenser) 117, a controller 119, temperature
measurement devices 29, 31, and 35, and various conduits and
valves. The apparatus may comprise one or more optional thermal
capacitors 105 and 207 with corresponding temperature measurement
devices 33 and 37.
[0061] The method comprises withdrawing a first quantity of gas
from gas source 7. The gas source may be one or more tanks or
vessels, a pipeline, or any other known source for the gas. The
first quantity of gas may be an amount sufficient to refill a
vehicle fuel tank, for example 3 kg to 10 kg.
[0062] The first quantity of gas is cooled via heat exchange with
first thermal capacitor 101. Upon initial cooling of the first
quantity of gas, the first thermal capacitor 101 has a temperature
that is lower than the minimum temperature of a first target
temperature range. For example, if the first target temperature
range is -33.degree. C. to -40.degree. C., the temperature of the
first thermal capacitor 101 is less than -40.degree. C. The
temperature of the first thermal capacitor 101 may be as cold as
-60.degree. C.
[0063] As used herein, a thermal capacitor is any thermal storage
element capable of releasing heat to a refrigerant and/or the gas,
and absorbing heat from the refrigerant and/or the gas. A thermal
capacitor may have a thermal mass greater than 40 kJ/K. The thermal
mass is the mass of an object multiplied by the specific heat
capacity of the object. A thermal capacitor may comprise a metal.
The metal may be aluminum. A thermal capacitor may comprise a
liquid. The liquid may be a liquid hydrocarbon. The liquid
hydrocarbon may be a C10 to C13 iso-alkane, for example
Therminol.RTM. D12 heat transfer fluid. A thermal capacitor may
comprise a phase change material. The phase change material may be
a eutectic comprising Sb, Te, and Ge (cf. Phase Change Materials,
Science and Applications, Simone Raoux and Matthias Wuttig,
Editors, Springer Science+Business Media, New York, 2009.
[0064] Thermal capacitors are preferably insulated to prevent
heating of the thermal capacitors by the surrounding ambient
air.
[0065] After being cooled via heat exchange with the first thermal
capacitor, the first quantity of gas is cooled via heat exchange
with second thermal capacitor 103. Upon initial cooling of the
first quantity of gas, the second thermal capacitor 103 has a
temperature that is lower than the minimum temperature of the first
target temperature range.
[0066] After being cooled via heat exchange with the second thermal
capacitor, the first quantity of gas may be heated or cooled via
heat exchange with a third thermal capacitor 107. The third thermal
capacitor has a temperature within the first target temperature
range. If the temperature of the first quantity of gas is less than
the minimum temperature of the first target temperature range after
exchanging heat with previous thermal capacitors, the third thermal
capacitor 107 will heat the first quantity of gas to a temperature
within the first target temperature range. If the temperature of
the first quantity of gas is greater than the maximum temperature
of the first target temperature range after exchanging heat with
previous thermal capacitors, the third thermal capacitor 107 will
cool the first quantity of gas to a temperature within the first
target temperature range.
[0067] After the temperature of the first quantity of gas has been
brought within first target temperature range via heat exchange
with the third thermal capacitor, the first quantity of gas, having
a dispensing temperature within the first target temperature range,
is introduced into a first receiving vessel (not shown) via conduit
137 and a dispensing connector (not shown). The first receiving
vessel may be part of a vehicle such as a car, truck, bus, or
forklift. The dispensing connector may be any suitable dispensing
connector for dispensing the gas to a receiving vessel. Dispensing
connectors are known in the art.
[0068] The gas flow rate may be controlled to provide a specified
mass flow rate or a pressure ramp rate.
[0069] As shown in the figure, the first quantity of gas may be
cooled by additional thermal capacitors 105 between cooling in the
second thermal capacitor 103 and heating or cooling in the third
thermal capacitor 107.
[0070] The thermal masses of the thermal capacitors may be the same
or different. The first thermal capacitors in the series may each
have the same thermal mass while the final thermal capacitor has a
different thermal mass. The first thermal capacitor in the series
may have a thermal mass different from the remaining thermal
capacitors in the series.
[0071] The advantage of using multiple thermal capacitors is that
the thermal capacitors that the gas passes through first may be
cooled well below the target temperature range. The gas is brought
within the target temperature range via heat exchange with the
final thermal capacitor. Properly designed, there is then no risk
of delivering the gas at a temperature below the minimum
temperature of the target temperature range. By cooling the first
thermal capacitors below the minimum temperature of the target
temperature range allows the compressor to run longer once turned
on.
[0072] After the first quantity of gas has been dispensed to the
first receiving vessel, a second quantity of gas having a
temperature within the first target temperature range may be
dispensed to a second receiving vessel.
[0073] The method may further comprise withdrawing a second
quantity of gas from gas source 7. The second quantity of gas may
be an amount sufficient to refill a vehicle fuel tank, for example
3 kg to 10 kg.
[0074] The second quantity of gas is cooled via heat exchange with
first thermal capacitor 101. The second quantity of gas is
subsequently cooled via heat exchange with second thermal capacitor
103.
[0075] After being cooled via heat exchange with the second thermal
capacitor, the second quantity of gas may be heated or cooled via
heat exchange with the third thermal capacitor 107. The third
thermal capacitor has a temperature within the first target
temperature range. If the temperature of the second quantity of gas
is less than the minimum temperature of the first target
temperature range after exchanging heat with previous thermal
capacitors, the third thermal capacitor 107 will heat the second
quantity of gas to a temperature within the first target
temperature range. If the temperature of the second quantity of gas
is greater than the maximum temperature of the first target
temperature range after exchanging heat with previous thermal
capacitors, the third thermal capacitor 107 will cool the second
quantity of gas to a temperature within the first target
temperature range.
[0076] After the temperature of the second quantity of gas has been
brought within the first target temperature range via heat exchange
with the third thermal capacitor, the second quantity of gas,
having a dispensing temperature within the first target temperature
range, is introduced into a second receiving vessel (not shown) via
conduit 137 and a dispensing connector (not shown). The second
receiving vessel may be part of a vehicle such as a car, truck,
bus, or forklift.
[0077] The second quantity of gas may be cooled by additional
thermal capacitors 105 between cooling in the second thermal
capacitor 103 and heating or cooling in the third thermal capacitor
107.
[0078] Setting of the minimum and maximum values for the first
target temperature range may be dependent upon a measured ambient
temperature. The method may comprise measuring an ambient
temperature representative of conditions surrounding any receiving
vessels prior to filling. The ambient temperature may be measured
by any suitable temperature sensor, shown schematically in the
figure as temperature sensor 57. Presumably, the temperature of any
residual gas in receiving vessels prior to filling will be at or
near ambient temperature. The temperature sensor 57 for determining
the ambient temperature should generally not be in direct sunlight.
Setting of the minimum and maximum values of the first target
temperature range may be dependent upon any measured temperature in
the receiving vessel prior to fill, the measured temperature as may
be available from a communication fill. This may be suitable to
determine if the vehicle, for example on a cold day, just arrived
for refueling from a warm garage, thus having a receiving vessel at
a temperature higher than ambient temperature.
[0079] The reason for adjusting the minimum and maximum values for
the first target temperature range is that the degree of cooling
necessary to prevent overheating of the receiving vessel may depend
on the ambient temperature. On cold days, less cooling of the gas
is required. Furthermore, by maintaining the thermal capacitors at
higher temperatures on cold days saves on energy required for
cooling the thermal capacitors.
[0080] It may be desirable to have the option to dispense different
batches of gas within different target temperature ranges, for
example, depending upon the ambient temperature and/or temperature
of the receiving vessel.
[0081] A third quantity of gas may be dispensed to a third
receiving vessel wherein the third quantity of gas is dispensed at
a dispensing temperature within a second target temperature range
wherein the second target temperature range is different than the
first target temperature range. The second target temperature range
may be preset by the device or selected by a user or operator. The
second target temperature range has a minimum temperature and a
maximum temperature.
[0082] For example, the first target temperature range may be
-40.degree. C. to -33.degree. C. and the second target temperature
range may be -20.degree. C. to +3.degree. C. The user or operator
may want the option to choose whether to dispense the gas within
the first temperature range or the second temperature range. The
first temperature range may be selected, for example, if the
ambient temperature is greater than 15.degree. C. and/or the
temperature measured in the receiving tank is greater than
15.degree. C., and the second temperature range may be selected if
the ambient temperature is less than 15.degree. C.
[0083] In case, it is desired to dispense the gas within the second
temperature range, the method may further comprise withdrawing a
third quantity of gas from gas source 7. The third quantity of gas
may be an amount sufficient to refill a vehicle fuel tank, for
example 3 kg to 10 kg.
[0084] The third quantity of gas is cooled via heat exchange with
first thermal capacitor 101. The third quantity of gas is
subsequently cooled via heat exchange with second thermal capacitor
103.
[0085] After being cooled via heat exchange with the second thermal
capacitor, the third quantity of gas may be heated or cooled via
heat exchange with a fourth thermal capacitor 207. The fourth
thermal capacitor has a temperature within the second target
temperature range. If the temperature of the third quantity of gas
is less than the minimum temperature of the second target
temperature range after exchanging heat with previous thermal
capacitors, the fourth thermal capacitor 207 will heat the third
quantity of gas to a temperature within the second target
temperature range. If the temperature of the third quantity of gas
is greater than the maximum temperature of the second target
temperature range after exchanging heat with previous thermal
capacitors, the fourth thermal capacitor 207 will cool the third
quantity of gas to a temperature within the second target
temperature range.
[0086] After the temperature of the third quantity of gas has been
brought within second target temperature range via heat exchange
with the fourth thermal capacitor, the third quantity of gas,
having a dispensing temperature within the second target
temperature range, is introduced into a third receiving vessel (not
shown) via conduit 237 and a dispensing connector (not shown). The
third receiving vessel may be part of a vehicle such as a car,
truck, bus, or forklift.
[0087] The third quantity of gas may be cooled by additional
thermal capacitors 105 between cooling in the second thermal
capacitor 103 and heating or cooling in the fourth thermal
capacitor 207.
[0088] Thermal capacitors 101, 103, 105 (if present), 107 and 207
(if present) are cooled in order to provide cooling of the gas. The
thermal capacitors may be cooled by heat exchange with a
refrigerant. The refrigerant may be any suitable refrigerant known
in the art, for example, R508A. The refrigerant is cycled in a
refrigeration cycle. As shown in the figure, the refrigerant is
compressed in compressor 157, cooled in heat exchanger (condenser)
117 and expanded through expansion valves 39, 41, 43 (if present),
45 and 245 (if present). The compressor and heat exchanger may be
part of a chiller unit such as a Trenton Refrigeration model
T150V6-HT3AB. The refrigerant expanded through valve 39 cools
thermal capacitor 101. The refrigerant expanded through valve 41
cools thermal capacitor 103. The refrigerant expanded through valve
43 cools thermal capacitor 105. The refrigerant expanded through
valve 45 cools thermal capacitor 107. The refrigerant expanded
through valve 245 cools thermal capacitor 207.
[0089] The thermal capacitors may be cooled by the refrigerant
while the gas is being cooled by the thermal capacitors. The
thermal capacitors may be cooled by the refrigerant at a time when
no gas is being cooled by the thermal capacitors.
[0090] The flow rate of the refrigerant to each of the thermal
capacitors may be independently controlled as shown in the figure
by valves 121, 123, 125, 127, and 129.
[0091] The temperature of each of the thermal capacitors may be
individually controlled by controlling the flow rate of refrigerant
to each respective thermal capacitor.
[0092] Temperature measurement devices 29, 31, 33, 35, and 37
measure the temperature of their respective thermal capacitors.
Controller 119 receives signals from the temperature measurement
devices and controls the flow rate of refrigerant through valves
121, 123, 125, 127, and 129 in order to maintain the desired
temperatures for the thermal capacitors.
[0093] In order to prevent heat conduction between each of the
thermal capacitors, any connecting pipes, tubes and the like may
constructed from materials having low thermal conductivity. For
example, stainless steel may be used rather than copper or brass or
other materials that are commonly used for refrigeration units.
[0094] Since the article "a" means "one or more," a second
refrigerant, a second compressor, and a second heat exchanger
(condenser) may be used in a second refrigeration cycle. Some of
the thermal capacitors may be cooled by a first refrigerant cycled
in a first refrigeration cycle and some other thermal capacitors
may be cooled by a second refrigerant in a second refrigeration
cycle. The first refrigerant and the second refrigerant may be the
same or different.
[0095] The advantage of using multiple refrigeration cycles is that
the dispensing station capacity is increased while allowing each of
the individual compressors to remain on for longer periods of time
once turned on, thereby increasing the life of each compressor.
[0096] In some instances, a receiving vessel in a sequence of
receiving vessels to receive the gas may not be capable of
receiving cold gas. For this case an optional bypass line 301 is
provided to bypass all the thermal capacitors. Consequently, the
method may further comprise withdrawing a fourth quantity of gas
from the gas source 7, and introducing the fourth quantity of gas
from the gas source into a fourth receiving vessel without cooling
the fourth quantity of gas between withdrawing the fourth quantity
of gas from the gas source and introducing the fourth quantity of
gas into the fourth receiving vessel.
[0097] Example (Comparative Case)
[0098] A single large aluminum block used to cool down hydrogen
from 35.degree. C. to -40.degree. C. at the start of a 5 kg fill,
and warming to the point where the hydrogen gas exits the aluminum
block at -33.degree. C. at the end of the fill would need to weigh
about 780 kgs. The aluminum block would not be able to be used
again for cooling the hydrogen gas down to -33.degree. C. until the
aluminum block is completely recooled after the fill.
[0099] Example (Multiple Thermal Capacitors)
[0100] This example contemplates a system with four thermal
capacitors in series for cooling hydrogen gas. The target
temperature range for dispensing the hydrogen gas is -37.degree. C.
to -40.degree. C. in this example.
[0101] Each of the four thermal capacitors are made from aluminum
and have a mass of 200 kg corresponding to a thermal mass of about
182 kJ/K. For this example, the thermal capacitors are assumed to
be perfectly insulated.
[0102] Initially the first thermal capacitor, the second thermal
capacitor, and the third thermal capacitor are at -50.degree. C.
and the final thermal capacitor is -37.degree. C.
[0103] A flow rate of hydrogen totaling 5 kg is passed through each
of the thermal capacitors. The initial gas temperature from the gas
source is 35.degree. C. The initial portion of hydrogen that exits
from the first thermal capacitor exits at a temperature of about
-43.degree. C. and the last portion exits at a temperature of about
-13.degree. C. The first thermal capacitor warms from -50.degree.
C. to -17.degree. C. as the first quantity of hydrogen is passed
through the first thermal capacitor.
[0104] Hydrogen entering the second thermal capacitor will exit at
temperatures from -49.degree. C. to -32.degree. C. as the second
thermal capacitor warms from -50.degree. C. to -46.degree. C.
Hydrogen entering the third thermal capacitor will exit at
temperatures from -45.degree. C. to -39.degree. C. as the third
thermal capacitor warms from -45.degree. C. to -44.degree. C.
Hydrogen entering the final thermal capacitor will exit at a
constant -37.degree. C. as the final thermal capacitor cools from
-37.degree. C. to -38.degree. C.
[0105] When it comes time to fill a second receiving vessel, if the
refrigeration plant is running, and has sufficient time between
fills, all of the thermal capacitors will be cooled to their normal
conditions (e.g. =50.degree. C. for the first, second, and third
thermal capacitor, and -38.degree. C. for the final thermal
capacitor).
[0106] If the refrigeration unit provides no cooling to the thermal
capacitors after filling the first receiving vessel and before
filling the second receiving vessel, the example assumes that the
thermal capacitors maintain their temperature at the end of filling
the first receiving vessel (-17.degree. C. for the first thermal
capacitor, -46.degree. C. for the second thermal capacitor,
-44.degree. C. for the third thermal capacitor, and -38.degree. C.
for the final thermal capacitor).
[0107] A second batch of hydrogen totaling 5 kg is passed through
each of the thermal capacitors. The initial gas temperature of the
second batch of gas from the gas source is 35.degree. C. The
initial portion of hydrogen that exits from the first thermal
capacitor exits at a temperature of about -13.degree. C. and the
last portion exits at a temperature of about +6.degree. C. The
first thermal capacitor warms from -17.degree. C. to +2.degree. C.
as the second quantity of hydrogen is passed through the first
thermal capacitor.
[0108] Hydrogen entering the second thermal capacitor will exit at
temperatures from -44.degree. C. to -22.degree. C. as the second
thermal capacitor warms from -46.degree. C. to -39.degree. C.
Hydrogen entering the third thermal capacitor will exit at
temperatures from -44.degree. C. to -34.degree. C. as the third
thermal capacitor warms from -44.degree. C. to -43.degree. C.
Hydrogen entering the final thermal capacitor will exit at a
constant -37.degree. C. as the final thermal capacitor stays at a
constant -38.degree. C.
[0109] In this example, the system will continue to keep the
hydrogen within the target temperature range for two more fills
without needing to turn on the refrigeration unit. Once the
relatively small refrigeration unit (10 kW for example) turns on,
it can run for up to 15 minutes per vehicle filled, an hour of
continuous running if four vehicles are filled, allowing the
refrigeration unit to be sized to balance the average thermal
demand, not just the peak refrigeration demand. The exiting gas
temperature stays at a constant temperature, and is not affected by
changes in flow rates.
* * * * *