U.S. patent application number 11/149766 was filed with the patent office on 2005-12-15 for metal hydride based vehicular exhaust cooler.
This patent application is currently assigned to HERA USA Inc.. Invention is credited to Golben, Peter Mark.
Application Number | 20050274493 11/149766 |
Document ID | / |
Family ID | 35459285 |
Filed Date | 2005-12-15 |
United States Patent
Application |
20050274493 |
Kind Code |
A1 |
Golben, Peter Mark |
December 15, 2005 |
Metal hydride based vehicular exhaust cooler
Abstract
A metal hydride heat pump comprising a first compartment,
including a first fluid inlet and a first fluid outlet, wherein the
first fluid inlet is configured for fluid communication with the
first fluid outlet; a second compartment, including a second fluid
inlet and a second fluid outlet, wherein the first fluid inlet is
configured for fluid communication with the second fluid outlet;
and a plurality of metal hydride vessels, each of the vessels being
mounted to and disposed within each of the first and second
compartments, and each of the vessels containing at least a
hydrided form of a low temperature metal hydride material, a
hydridable form of a high temperature metal hydride material, and
gaseous hydrogen, wherein the hydridable form of a high temperature
metal hydride material is in fluid communication with the hydrided
form of a low temperature metal hydride material, such that heat
can be transferred from (a) fluid flowing through the first
compartment to (b) the hydrided form of a low temperature metal
hydride material, so as to effect desorption of hydrogen from the
hydrided form of a low temperature metal hydride material, and such
that the hydridable form of a high temperature metal hydride
material is configured to absorb the desorbed hydrogen and generate
heat upon the absorption such that the generated heat can be
transferred to fluid flowing through the second compartment;
wherein each of the vessels has an external surface area, and
defines an internal volume for containing at least the hydrided
form of a low temperature metal hydride material, the hydridable
form of a high temperature metal hydride material, and gaseous
hydrogen, wherein a ratio of the external surface area to the
internal volume is greater than 45 inches.sup.2 per cubic inch.
Inventors: |
Golben, Peter Mark;
(Florida, NY) |
Correspondence
Address: |
HAYNES AND BOONE, LLP
901 MAIN STREET, SUITE 3100
DALLAS
TX
75202
US
|
Assignee: |
HERA USA Inc.
Ringwood
NJ
|
Family ID: |
35459285 |
Appl. No.: |
11/149766 |
Filed: |
June 10, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11149766 |
Jun 10, 2005 |
|
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10916371 |
Aug 11, 2004 |
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60578727 |
Jun 10, 2004 |
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Current U.S.
Class: |
165/104.12 |
Current CPC
Class: |
B60H 1/32 20130101; Y02E
60/142 20130101; F28D 20/003 20130101; Y02E 70/30 20130101; F25B
17/12 20130101; B60H 1/32011 20190501; Y02E 60/14 20130101 |
Class at
Publication: |
165/104.12 |
International
Class: |
F28D 015/00 |
Claims
What is claimed is:
1. A metal hydride heat pump comprising: a first compartment,
including a first fluid inlet and a first fluid outlet, wherein the
first fluid inlet is configured for fluid communication with the
first fluid outlet; a second compartment, including a second fluid
inlet and a second fluid outlet, wherein the first fluid inlet is
configured for fluid communication with the second fluid outlet;
and a plurality of metal hydride vessels, each of the vessels being
mounted to and disposed within each of the first and second
compartments, and each of the vessels containing at least a
hydrided form of a low temperature metal hydride material, a
hydridable form of a high temperature metal hydride material, and
gaseous hydrogen, wherein the hydridable form of a high temperature
metal hydride material is in fluid communication with the hydrided
form of a low temperature metal hydride material, such that heat
can be transferred from (a) fluid flowing through the first
compartment to (b) the hydrided form of a low temperature metal
hydride material, so as to effect desorption of hydrogen from the
hydrided form of a low temperature metal hydride material, and such
that the hydridable form of a high temperature metal hydride
material is configured to absorb the desorbed hydrogen and generate
heat upon the absorption such that the generated heat can be
transferred to fluid flowing through the second compartment;
wherein each of the vessels has an external surface area, and
defines an internal volume for containing at least the hydrided
form of a low temperature metal hydride material, the hydridable
form of a high temperature metal hydride material, and gaseous
hydrogen, wherein a ratio of the external surface area to the
internal volume is greater than 45 inches.sup.2 per cubic inch.
2. The metal hydride heat pump as claimed in claim 1, wherein each
of the vessels extends between the first and second compartments,
and also extends into each of the first and second
compartments.
3. The metal hydride heat pump as claimed in claim 2, wherein the
low temperature metal hydride material is contained in a portion of
the internal volume of the vessel disposed in the first
compartment, and the high temperature metal hydride material is
contained in a portion of the internal volume of the vessel
disposed in the second compartment.
4. The metal hydride heat pump as claimed in claim 2, wherein the
internal volume of the vessel contains an amount of metal hydride
material consisting essentially of (i) an amount of a hydrided
and/or a hydridable form of a low temperature metal hydride
material, and (ii) an amount of a hydrided and/or a hydridable form
of a high temperature metal hydride material, and wherein the
amount of a hydrided and/or a hydridable form of a low temperature
metal hydride material is substantially disposed in a portion of
the internal volume of the vessel disposed in the first
compartment, and wherein the amount of a hydrided and/or a
hydridable form of a high temperature metal hydride material is
substantially disposed in a portion of the internal volume of the
vessel disposed in the second compartment.
5. The metal hydride heat pump as claimed in claim 4, wherein the
amount of a hydrided and/or a hydridable form of a low temperature
metal hydride material has a first maximum hydrogen storage
capacity, and wherein the amount of a hydrided and/or a hydridable
form of a high temperature metal hydride material has a second
maximum hydrogen storage capacity, such that the first maximum
hydrogen storage capacity is 1% to 10% greater than the second
maximum hydrogen storage capacity.
6. The metal hydride heat pump as claimed in claim 5, wherein the
first maximum hydrogen storage capacity is 3% to 10% greater than
the second maximum hydrogen storage capacity.
7. The metal hydride heat pump as claimed in claim 6, wherein the
first maximum hydrogen storage capacity is 5% to 10% greater than
the second maximum hydrogen storage capacity.
8. The metal hydride heat pump as claimed in claim 3, wherein the
low temperature metal hydride material is
Ti.sub.FZr.sub.GHf.sub.HMn.sub.JV.s- ub.KFe.sub.LCr.sub.MNi.sub.N,
and wherein the high temperature metal hydride material is
Hf.sub.AZr.sub.BTi.sub.CNi.sub.DMm.sub.E.
9. The metal hydride heat pump as claimed in claim 1, wherein the
ratio is greater than 89.
10. The metal hydride heat pump as claimed in claim 1, wherein the
ratio is greater than 176.
11. The metal hydride heat pump as claimed in claim 1, wherein the
fluids flowing through each of the first and second compartments is
gaseous.
12. The metal hydride heat pump as claimed in claim 1, wherein each
of the vessels is in the form of an elongated tube sealed at both
ends.
13. The metal hydride heat pump as claimed in claim 1, wherein the
material of construction of each of the vessels is a stainless
steel alloy comprising less than 3 weight percent of carbon based
on the total weight of the stainless steel alloy.
14. The metal hydride heat pump as claimed in claim 3, wherein each
of the low temperature metal hydride material and the high
temperature metal hydride material is disproportionation
resistant.
15. The metal hydride heat pump as claimed in claim 3, wherein the
high temperature metal hydride material is
Ti.sub.FZr.sub.GHf.sub.HMn.sub.JV.s-
ub.KFe.sub.LCr.sub.MNi.sub.N.
16. A metal hydride heat pump comprising: a compartment, including
a first gas inlet and a first gas outlet, wherein the first gas
inlet is configured for fluid communication with the first gas
outlet; and a plurality of metal hydride vessels, each of the
vessels being mounted to and disposed within the compartment, and
each of the vessels containing at least a metal hydride material;
wherein the material of construction of each of the vessels is a
stainless steel alloy comprising less than 3 weight percent of
carbon based on the total weight of the stainless steel alloy.
17. A metal hydride heat pump comprising: a compartment, including
a first gas inlet and a first gas outlet, wherein the first gas
inlet is configured for fluid communication with the first gas
outlet; and a plurality of metal hydride vessels, each of the
vessels being mounted to and disposed within the compartment, and
each of the vessels containing at least a metal hydride material
and gaseous hydrogen; wherein each of the vessels has an external
surface area, and defines an internal volume for containing at
least the metal hydride material and gaseous hydrogen, wherein a
ratio of the external surface area to the internal volume is
greater than 45 inches.sup.2 per cubic inch.
18. The metal hydride heat pump as claimed in claim 17, wherein the
ratio is greater than 89.
19. The metal hydride heat pump as claimed in claim 17, wherein the
ratio is greater than 176.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part application of
U.S. patent application Ser. No. 10/916,371, filed Aug. 11, 2004,
and entitled "METAL HYDRIDE BASED VEHICULAR EXHAUST COOLER," which
application is a non-provisional of U.S. Provisional Patent
Application No. 60/578,727 entitled "METAL HYDRIDE BASED VEHICULAR
EXHAUST COOLER," filed Jun. 10, 2004, the disclosures of which are
incorporated by reference herein in their entireties.
FIELD OF THE INVENTION
[0002] This invention relates to the field of metal hydride-based
heat pumps and, in particular, metal hydride based heat pumps used
for air conditioning.
BACKGROUND OF THE INVENTION
[0003] A metal hydride based heat pump has been developed for
vehicular applications, and particularly for passenger compartment
air conditioning using energy from the hot exhaust gas of a
vehicle, such as an automobile. Although the invention is described
in relation to an automobile, it is understood that the present
invention can find application in any type of vehicle which
produces a hot exhaust gas.
[0004] There are a number of other heating and cooling applications
that might be satisfied by this metal hydride heat pump technology
including:
[0005] near instant passenger compartment heating for cold winter
days;
[0006] preheating the catalytic converter upon cold engine start up
to reduce air pollution emissions;
[0007] cooling for electronic components and batteries;
[0008] cooling engine inlet air to improve performance and
efficiency.
[0009] The source of energy for these heat pump applications could
be the hot exhaust gas, engine exhaust manifold or engine
coolant.
[0010] Existing automotive air conditioners use the conventional
freon refrigeration cycle. The freon air conditioner takes its
power directly from the engine via a belt driven compressor. When
the air conditioner operates, it consumes engine power that would
otherwise be available for propulsion. There is a corresponding
reduction in power available for acceleration and a reduction in
vehicle gasoline mileage.
[0011] There is sufficient energy in a usable temperature range in
the exhaust gas stream of an automotive internal combustion engine
to provide 100% of the air conditioning power requirement of a
Metal Hydride Automobile Air Conditioner (MIIAC) system. The major
benefit of this power source is the elimination of the freon
compressor, belts and pulleys from the engine and the electric
compressor clutch. Without the compressor's drag on the engine,
more engine power is available for propulsion, thus increasing
acceleration, overall efficiency and gas mileage.
[0012] Another major benefit of the MHAC system is that it does not
use freon and is environmentally sound. Freon has been identified
as the major contributor to atmospheric ozone depletion. Fifty
percent (50%) of the world's freon is associated with air
conditioning and refrigeration equipment including automobile air
conditioners. New refrigerant formulations are claimed to cause
only 10% of the environmental damage of today's freon, but even
this rate is unacceptably high. The MHAC uses a sealed, low
pressure system containing non-polluting hydrogen gas as the safe
and effective working fluid. These attributes make the MHAC an
excellent candidate for the next generation of automotive air
conditioning technology.
SUMMARY OF THE INVENTION
[0013] In one aspect the present invention provides a metal hydride
heat pump comprising a first compartment, including a first fluid
inlet and a first fluid outlet, wherein the first fluid inlet is
configured for fluid communication with the first fluid outlet; a
second compartment, including a second fluid inlet and a second
fluid outlet, wherein the first fluid inlet is configured for fluid
communication with the second fluid outlet; and a plurality of
metal hydride vessels, each of the vessels being mounted to and
disposed within each of the first and second compartments, and each
of the vessels containing at least a hydrided form of a low
temperature metal hydride material, a hydridable form of a high
temperature metal hydride material, and gaseous hydrogen, wherein
the hydridable form of a high temperature metal hydride material is
in fluid communication with the hydrided form of a low temperature
metal hydride material, such that heat can be transferred from (a)
fluid flowing through the first compartment to (b) the hydrided
form of a low temperature metal hydride material, so as to effect
desorption of hydrogen from the hydrided form of a low temperature
metal hydride material, and such that the hydridable form of a high
temperature metal hydride material is configured to absorb the
desorbed hydrogen and generate heat upon the absorption such that
the generated heat can be transferred to fluid flowing through the
second compartment; wherein each of the vessels has an external
surface area, and defines an internal volume for containing at
least the hydrided form of a low temperature metal hydride
material, the hydridable form of a high temperature metal hydride
material, and gaseous hydrogen, wherein a ratio of the external
surface area to the internal volume is greater than 45 inches.sup.2
per cubic inch.
[0014] In another aspect the present invention provides a metal
hydride heat pump comprising a compartment, including a first gas
inlet and a first gas outlet, wherein the first gas inlet is
configured for fluid communication with the first gas outlet; and a
plurality of metal hydride vessels, each of the vessels being
mounted to and disposed within the compartment, and each of the
vessels containing at least a metal hydride material; wherein the
material of construction of each of the vessels is a stainless
steel alloy comprising less than 3 weight percent of carbon based
on the total weight of the stainless steel alloy.
[0015] In a further aspect the present invention provides a metal
hydride heat pump comprising a compartment, including a first gas
inlet and a first gas outlet, wherein the first gas inlet is
configured for fluid communication with the first gas outlet; and a
plurality of metal hydride vessels, each of the vessels being
mounted to and disposed within the compartment, and each of the
vessels containing at least a metal hydride material and gaseous
hydrogen; wherein each of the vessels has an external surface area,
and defines an internal volume for containing at least the metal
hydride material and gaseous hydrogen, wherein a ratio of the
external surface area to the internal volume is greater than 45
inches.sup.2 per cubic inch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention will be better understood by reference to the
following detailed description of the invention in conjunction with
the following drawings in which:
[0017] FIG. 1 is a schematic illustration of a metal hydride-based
air conditioner in a cooling mode;
[0018] FIG. 2 is a schematic illustration of a metal hydride-based
air conditioner in a recharge mode;
[0019] FIG. 3 shows the test apparatus and plot;
[0020] FIG. 4 shows the sample metal hydride Van't Hoff plot;
[0021] FIG. 5 shows the Van't Hoff Plot of the thermal dynamic
cycle for a metal hydride air conditioner;
[0022] FIG. 6A shows the operational schematic for process Step
1;
[0023] FIG. 6B shows the Van't Hoff thermal dynamic plot for
process Step 1;
[0024] FIG. 7A shows the operational schematic for process Step
2;
[0025] FIG. 7B shows the Van't Hoff thermal dynamic plot for
process Step 2;
[0026] FIG. 8 is a sectional view of the single metal hydride heat
exchanger, showing major components;
[0027] FIG. 9A shows the single metal hydride tube in recharge
mode;
[0028] FIG. 9B shows the single metal hydride tube in cooling
mode;
[0029] FIG. 10 shows the metal hydride tube placement in the bench
top MHAC;
[0030] FIG. 11 is a view of the two beds, metal hydride heat
exchangers;
[0031] FIG. 12 is a top view schematic of the top MH bed in the
MHAC;
[0032] FIG. 13 is a top view schematic of the bottom MH bed in the
MHAC;
[0033] FIG. 14 shows the gate valve operation for the inlet side of
the MHAC unit--Position 1;
[0034] FIG. 15 shows the gate valve operation for the inlet side of
the MHAC unit--Position 2.
[0035] FIG. 16 shows the gate valve operation for the outlet side
of the MHAC Unit--Position 1; and
[0036] FIG. 17 shows the gate valve operation for the outlet side
of the MHAC Unit--Position 2.
DETAILED DESCRIPTION
[0037] There are a number of metals that possess the remarkable
ability to absorb large quantities of hydrogen gas. Absorption
occurs under specific temperature and pressure conditions. The
hydrogen is released (desorbed) when the alloy temperature is
elevated or the pressure is reduced. The absorption/desorption
phenomenon is a "reversible" reaction and the metals that absorb
hydrogen are called reversible metal hydride materials.
[0038] When a reversible metal hydride material absorbs hydrogen
gas, heat is given off; the reaction is exothermic. In order to
desorb hydrogen from the metal hydride material, heat is required;
the reaction is endothermic. If the desorbing material takes its
heat from ambient temperature air, the air temperature decreases,
thus producing the refrigeration associated with air
conditioning.
[0039] The reversible metal hydride reaction can be expressed in
the simplified chemical equation:
M+HMH
[0040] where M is a metal or metal alloy and H is hydrogen. The top
arrow in the equation signifies the absorption cycle:
M+H.fwdarw.MH+heat
[0041] The lower arrow shows the reversibility of the reaction and
signifies the desorption cycle:
M+H.rarw.MH+heat in
[0042] The reversibility of the metal hydrogen reaction and the
heat associated with it provide the basis for hydride heat pumps.
The heat pump is a closed unit in which hydrogen serves as an
energy carrier between two or more hydride beds. By selecting
appropriate hydriding materials, heat sources, and heat sinks, heat
can be pumped over wide temperature differentials. Elements of the
process are illustrated in FIGS. 1 and 2.
[0043] FIG. 1 illustrates an air conditioner in the cooling mode.
Hydrogen which has been stored as a solid metal hydride in the left
hand bed is desorbed or released. The hydrogen flows into the right
hand bed (mechanical pumping is not required). The heat necessary
for desorption is taken from passenger compartment air, causing
cooling of the passenger compartment.
[0044] When all of the hydrogen has been desorbed from the left
hand hydride bed (and subsequently absorbed by the right hand bed),
it must be recharged into the left hand bed to become available for
additional cooling. FIG. 2 illustrates the recharge mode. Here, the
right hand bed is heated by exhaust gas causing it to release its
hydrogen which then returns to the left hand bed.
[0045] The MHAC consists of a minimum of two (paired) 2-bed
systems. One pair of beds operates in the cooling mode while the
other pair is in the recharge mode. In this way, continuous cooling
is available for passenger compartment air conditioning.
[0046] FIG. 3 shows a simple test set up along with a sample PCT
(Pressure/Composition/Temperature isotherm) curve which describes
the hydriding reaction in more detail. In this test procedure, a
sample of metal hydride is placed inside a container which has a
pressure gauge and valve. Initially, this container is fully
evacuated so that the hydride pressure and capacity (the amount of
hydrogen "inside" the container) is zero. This condition
corresponds to point A in FIG. 3. Slowly the valve on the container
is opened and hydrogen gas is allowed to enter into the container.
When this happens, the pressure in the container immediately rises
until point B is reached. This is the point where hydrogen begins
to enter into the metal hydride material. Between point B and C in
FIG. 3, hydrogen continues to enter into the container but no
pressure rise is observed. Therefore, all of this hydrogen has gone
into the metal hydride material. After the material is "fully
charged" with hydrogen, the pressure in the container will resume
its pressure rise as more hydrogen enters the container. This test
has now generated the alloy's PCT curve that shows where the
"plateau" (between points B and C) lies. This PCT test is done at a
constant temperature and, therefore, determines the pressure the
alloy "generates" at a given temperature. Remember, during the
absorption of hydrogen into the metal, heat is generated and must
be "transferred" out of the metal hydride. Correspondingly, when
hydrogen leaves the metal hydride (i.e: desorption), heat must be
transferred into the metal hydride.
[0047] It has been found that this plateau pressure changes
exponentially with temperature. If the plateau pressure is plotted
using the logarithm scale of pressure as the abscissa and the
inverse of absolute temperature as the ordinate, then a straight
line plot of the plateau pressure change vs the temperature
results. FIG. 4 shows a sample plot of such a curve, which is
called the "Van't Hoff plot" for this particular metal hydride
material.
[0048] The key to a successful metal hydride air conditioner is the
selection of the "right" metal hydride materials and heat
exchangers in which to use them. FIG. 5 is a plot of such a pair of
metal hydride materials, material A on this graph is the "high
temperature" metal hydride material and material B is the "low
temperature" metal hydride material. Looking at FIG. 5, the
thermodynamic process of a metal hydride air conditioner can be
followed:
[0049] Process A--Hydrogen gas, coming from the low temperature
metal hydride material, flows into the high temperature material.
In order for this process to occur, heat must be provided to the
low temperature material B, simultaneously an equal amount of heat
must be removed from the high temperature material A. The interior
car air provides this heat for material B and thus gets cold.
Outside ambient air removes material A's heat of absorption.
[0050] Process B--The high temperature material A has been heated
up to the exhaust gas temperature which now enables the hydrogen
gas to flow from material A back into material B. The heat that is
needed to remove the hydrogen from material A is provided by the
hot exhaust gas. The corresponding heat that is generated in
material B as hydrogen gas enters it is dissipated to the heat
sink, which is the ambient air.
[0051] From FIG. 5, the coefficient of performance (COP) of the air
conditioner can be determined. The COP of a heat pump type air
conditioner is defined as: 1 COP = Amount of heat you put in Amount
of heat ( i . e . cooling ) you produce = QH QC
[0052] Therefore, the theoretical best COP would be equal to 1,
meaning that you are producing an equivalent amount of cooling as
to the heat you must supply.
[0053] Since the production of cooling in a metal hydride air
conditioner is a "batch" type process, two pairs of metal hydride
heat exchangers must be employed to produce continuous cooling.
Therefore, while one pair is cooling, the other pair is being
regenerated with the hot exhaust heat. FIGS. 6A and 6B (Step 1) and
FIGS. 7A and 7B (Step 2) demonstrate this batch process.
[0054] FIG. 6A shows the schematic layout and ducting of the two
pairs of metal hydride heat exchangers when the air conditioner is
in the "Step 1" mode. Here metal hydride heat exchanger pair
H.sub.1 and L.sub.1 are producing cooling while heat exchanger pair
H.sub.2 and L.sub.2 are being regenerated. FIG. 6B shows the Van't
Hoff plot conditions for each alloy in Step 1. Notice that the
control of air flow through the air conditioner is accomplished
with the use of simple louvers. Physically, in Step 1 (FIG. 6A),
the following heat transfer processes are occurring:
[0055] a) Interior car air is passing through metal hydride heat
exchanger L.sub.1. Since L.sub.1 is in the desorbing mode, heat is
being removed from the interior car air stream.
[0056] b) At the same time, ambient air is passing through metal
hydride heat exchanger L.sub.2. Since hydrogen is being absorbed by
this material, heat is being generated which is dissipated to the
outside ambient air stream.
[0057] c) Hot exhaust gas is passing through metal hydride heat
exchanger H.sub.2. Heat from this exhaust gas stream is used to
"release" the hydrogen in this heat exchanger.
[0058] d) Ambient air is passing through metal hydride heat
exchanger H.sub.1. Since H.sub.1 is absorbing hydrogen gas, this
heat of absorption is dissipated to the outside ambient air.
[0059] After the Step 1 process is complete, the air flow control
louvers will switch and redirect the air flow so that Step 2 can
start. In Step 2, metal hydride heat exchanger pairs H.sub.2 and
L.sub.2 now produce the cooling and pair H.sub.1 and L.sub.1 are
being regenerated. FIG. 7A shows the operational schematics for
this process with FIG. 7B showing the corresponding Van't Hoff
thermodynamic plots. The physical Step 2 processes occurring (shown
in FIGS. 7A and 7B) are:
[0060] a) Ambient air is now passing through heat exchanger
L.sub.1, thus removing its heat of formation.
[0061] b) Interior car air is passing through heat exchanger
L.sub.2. Since exchanger L.sub.2 is in the desorption mode, heat is
being removed from the interior car air.
[0062] c) Ambient air is passing through heat exchanger H.sub.2 and
removing the heat that is being generated in H.sub.2.
[0063] d) Hot exhaust gas is passing through heat exchanger H.sub.1
and supplying the heat needed to release the hydrogen gas in
exchanger H.sub.1.
[0064] Metal hydride air conditioners are based on the principle of
transporting hydrogen gas back and forth between two heat
exchangers containing metal hydride material.
[0065] Cooling is generated when the hydrogen gas "leaves" the
metal hydride material. Conversely, heat is generated when the
hydrogen gas "enters" the metal hydride material.
[0066] In one embodiment, about 40% of the total mass of a metal
hydride heat exchanger is non-metal hydride material. Therefore,
the remaining 60% of mass is metal hydride material.
[0067] Twenty-five percent (25%) of the total envelope of the metal
hydride heat exchanger is containment vessel volume, therefore, 75%
of the envelope volume is available for air flow.
[0068] The percent volume of metal hydride material in the
containment vessel volume is about 33%. Therefore, about 8% of the
total envelope volume of the metal hydride heat exchanger is metal
hydride material.
[0069] The metal hydride air conditioner (MHAC), or heat pump, is
of a "multi-tube" design.
[0070] Referring to FIGS. 8 to 15, the metal hydride heat pump 10
is a shell and tube heat exchanger comprised of two (in this case
"top" and "bottom") hydride tube beds, each disposed in separate
housings 12, 14. The heat pump 10 has 356 straight hydride tubes
per bed (712 tubes total). The hydride tube pattern is rectangular.
A tubesheet 16 partitions each bed into a hot exhaust section and a
cooling section, and also partitions each housing into first and
second compartments 18, 20. The tubesheet 16 is perforated (i.e.
includes apertures) for receiving the hydride tubes and thereby
providing support for the hydride tubes 22. The heat pump is
insulated internally.
[0071] Each of the first and second housings 12, 14 is mounted to a
common frame 24. In this embodiment, the first housing 12 is
mounted above the second housing 14. The first housing 12 includes
a first compartment 18 and a second compartment 20. The first
compartment 18 of the first housing 12 is a "tubular" structure,
defined by top and bottom walls 24, 26, and first and second
sidewalls 28, 30. Each of the top and bottom walls 24, 26 is joined
to each of the sidewalls 28, 30. Each of the top and bottom walls
24, 26, and sidewalls 30 are manufactured from stainless steel.
Opposing gas inlet 32 and gas outlet 34 openings are provided and
are configured to effect flow of gas through the first compartment.
The second sidewall 30 is perforated (i.e. includes apertures) to
permit insertion of the metal hydride tubes 32 of the hydride tube
beds therethrough, thereby effecting at least partial support of
the metal hydride tubes 22 (i.e. the mounting of the metal hydride
tubes to the first compartment).
[0072] The second compartment 20 is substantially the same as the
first compartment 18, and includes top and bottom walls 24, 26,
first and second sidewalls 28, 30, and gas inlet 32, and gas outlet
34, openings. The second sidewall is also perforated (i.e. includes
apertures) to permit insertion of the metal hydride tubes of the
first of the two hydride tube beds, thereby effecting at least
partial support of the metal hydride tubes (i.e. the mounting of
the metal hydride tubes to the second compartment).
[0073] Each of the walls of the first and second compartments is
thermally insulated. In this respect, the inside surface of each
wall is covered with 1/4 of an inch of high temperature ceramic
fiber insulation.
[0074] A ceramic insulator 36 is provided between the second
sidewalls 30, 301 of the respective first and second compartments
18, 20. The ceramic insulator 36 is also perforated (i.e. apertures
are provided). Each of the second sidewalls 30 and the insulator
are coupled to one another with appropriate fasteners, causing the
ceramic insulator to be pressed between the second sidewalls 30,
301. When coupled together, the perforations in the second
sidewalls 30, 301 and the insulator 36 are in alignment to permit
insertion of the metal hydride tubes 22 therethrough so that the
metal hydride tubes 22 become disposed with each of the first and
second compartments 18, 20. In this respect, the coupled second
sidewalls and the insulator functions as the tubesheet 16.
[0075] The first housing 12 includes a first channel 38 extending
peripherally from the bottom wall of the front side of the first
housing, and also includes a second channel 381 extending
peripherally from the bottom wall of the rear side of the housing
12. The first and second channels are provided to support and
facilitate sliding movement of inlet and outlet sliding gates 40,
4011, respectively.
[0076] The inlet sliding gate 40 opens and closes the gas inlets
32, 321. In this respect, the inlet sliding gate includes a first
opening 401 which is configured to simultaneously register with the
gas inlet of the first compartment and one of (i) a first conduit,
for effecting fluid communication between the gas inlet and the
first conduit and thereby providing passenger compartment air flow
to the first compartment 18, and (ii) a second conduit, for
effecting fluid communication between the gas inlet and the second
conduit and thereby providing ambient air flow to the first
compartment 18. The inlet sliding gate also includes a second
opening 402 which is configured to simultaneously register with the
gas inlet of the second compartment and one of (i) the second
conduit, for effecting fluid communication between the gas inlet
and the second conduit and thereby providing ambient air flow to
the second compartment 20, and (ii) a third conduit, for effecting
fluid communication between the gas inlet and the third conduit and
thereby providing exhaust gas flow to the second compartment
20.
[0077] The inlet gate 40 is slideably moveable, so that in a first
inlet gate position, the first opening simultaneously registers
with the gas inlet of the first compartment 18 and the first
conduit, and the second opening simultaneously registers with the
gas inlet of the second compartment 20 and the second conduit. The
inlet gate is also slideably moveable to a second inlet gate
position, wherein the first opening simultaneously registers with
the gas inlet of the first compartment 18 and the second conduit,
and the second opening simultaneously registers with the gas inlet
of the second compartment 20 and the third conduit.
[0078] The outlet sliding gate 4011 opens and closes the gas
outlets 34, 341. In this respect, the outlet sliding gate 4011
includes a first opening 4013 which is configured to simultaneously
register with the gas outlet of the first compartment and one of
(i) a fourth conduit, for effecting fluid communication between the
gas outlet and the fourth conduit and thereby returning the cooled
interior air to the passenger compartment from the first
compartment, and (ii) a fifth conduit, for effecting fluid
communication between the gas outlet and the fifth conduit and
thereby exhausting the heated ambient air from the first
compartment. The outlet sliding gate 4011 also includes a second
opening 4015 which is configured to simultaneously register with
the gas outlet of the second compartment and (i) the fifth conduit,
for effecting fluid communication between the gas outlet and the
sixth conduit and thereby exhausting the heated ambient air from
the second compartment, or (ii) a sixth conduit, for exhausting the
cooled exhaust from the second compartment.
[0079] The outlet gate is slideably moveable, so that in a first
outlet gate position, the first opening simultaneously registers
with the gas outlet of the first compartment and the fourth
conduit, and the second opening simultaneously registers with the
gas outlet of the second compartment and the fifth conduit. The
outlet gate is also slideably moveable to a second outlet gate
position, wherein the first opening simultaneously registers with
the gas outlet of the first compartment and the fifth conduit, and
the second opening simultaneously registers with the gas outlet of
the second compartment and the sixth conduit.
[0080] Sliding movement of each of the inlet and outlet gates 40,
4011 is actuated by respective, separate extendible/retractable
pistons 42, 4022. Each piston is coupled to a respective one of the
inlet and outlet gates 40, 4011. Each piston is mounted to the
frame of the heat pump 10.
[0081] In one embodiment, the two pistons are configured to actuate
the respective inlet and outlet gates so that the outlet gate is in
the first outlet gate position when the inlet gate is in the first
inlet gate position (cooling mode). Also, the two pistons are
configured to actuate the respective inlet and outlet gates so that
the outlet gate is in the second outlet gate position when the
inlet gate is in the second inlet gate position (i.e. regeneration
mode).
[0082] The second housing 12 is configured to be substantially the
same as the first housing 10. The inlet sliding gate of the second
housing is coupled to the same actuating piston used to actuate the
inlet sliding gate of the first housing. Similarly, the outlet
sliding gate of the second housing is coupled to the same actuating
piston used to actuate the outlet sliding gate of the first
housing.
[0083] The hydride tubes 22 function as vessels defining an
internal volume. Each of the vessels contains at least metal
hydride material and gaseous hydrogen within the internal volume.
The tubes are made of low carbon 316 seamless stainless steel.
Preferably, the stainless steel alloy comprises less than 3 wt %
carbon based on total weight of the alloy. The use of low carbon
stainless steel reduces the amount of CH.sub.4 that could be
generated in the tubes at high temperatures. The tubes are rated
for 3000 psi pressure.
[0084] In one embodiment, the ratio of the external surface area of
the vessel to the internal volume of the vessel is greater than 45
inches.sup.2/inches.sup.3. Preferably, the ratio is greater than 89
in.sup.2/in.sup.3. Even more preferably, the ratio is greater than
176 in.sup.2/in.sup.3.
[0085] In another embodiment, when the vessel is in the form of an
elongated tube sealed at both ends, the tube has an outside
diameter less than 1/8 (0.125) of an inch. Preferably, the outside
diameter is less than {fraction (1/16)} (0.0625) of an inch (with a
wall thickness of 0.005 inches). More preferably, the outside
diameter is less than {fraction (1/32)} (0.03125) of an inch (with
a wall thickness of 0.0025 inches).
[0086] In one embodiment, the metal hydride heat pump 10 has two
hydride tube beds; one bed provides cooling while the other is
being recharged. The cycle time for each bed is split into two
"half cycles" for regeneration. The hydride tube beds are operated
180.degree. out of phase in order to provide continuous cooling of
passenger compartment air.
[0087] Each hydride bed contains 356-{fraction (1/16)} of an inch
diameter outside by 24 inches long straight low carbon stainless
steel tubes. FIG. 8 shows a simple cutaway view of a single metal
hydride tube element 22. This element consists of a 24 inch long,
0.0625 ({fraction (1/16)}) inch in outer diameter, stainless steel
tube. Inside this small tube are two different metal hydride
materials. The "high temperature" material 44 is shown to occupy
the right hand section of the tube (as shown in FIG. 8) and the low
temperature material 46 is shown to occupy the left hand section. A
hydrogen conduit 48 is axially disposed along the length of the
tube to facilitate flow of hydrogen gas between the two materials.
A disposition of a hydrogen conduit in a tube of an embodiment of
the present invention is described in U.S. Pat. No. 4,396,114,
which is incorporated herein by reference.
[0088] In one embodiment, for example, the high temperature metal
hydride material (hydridable form) is characterized by the
formula:
Hf.sub.AZr.sub.BTi.sub.CNi.sub.DMm.sub.E,
[0089] wherein
[0090] A=0.20 to 1.50
[0091] B=0 to 0.50
[0092] C=0 to 1.00
[0093] D=0.10 to 1.50, and
[0094] E=0 to 0.20
[0095] In one embodiment, for example, the low temperature metal
hydride material (hydridable form) is characterized by the
formula:
Ti.sub.FZr.sub.GHf.sub.HMn.sub.JV.sub.KFe.sub.LCr.sub.MNi.sub.N
[0096] wherein
[0097] F=0.20 to 1.00
[0098] G=0 to 0.80
[0099] H=0 to 0.80
[0100] J=0.50 to 2.00
[0101] K=0 to 1.50
[0102] L=0 to 0.50
[0103] M=0 to 0.50, and
[0104] N=0 to 0.50
[0105] In one embodiment, for example, the high temperature metal
hydride material (the hydridable form) is
Hf.sub.1.0Ni.sub.0.98Mm.sub.0.02, and the low temperature metal
hydride material (the hydridable form) is
Ti.sub.0.932Zr.sub.0.052Mn.sub.1.498V.sub.0.464Fe.sub.0.091Cr.sub.0.001Ni-
.sub.0.0005.
[0106] Mm denotes mischmetal, a mixture of "rare earth" (lanthanum
type) elements.
[0107] It is understood that the alloy
Ti.sub.FZr.sub.GHf.sub.HMn.sub.JV.s- ub.KFe.sub.LCr.sub.MNi.sub.N
may also function as the high temperature metal hydride
material.
[0108] For example,
Ti.sub.0.932Zr.sub.0.052Mn.sub.1.498V.sub.0.464Fe.sub.-
0.091Cr.sub.0.001Ni.sub.0.0005 may function as the high temperature
metal hydride material, and a different alloy would function as the
low temperature metal hydride material.
[0109] The term "hydrided form" refers to a form of the metal
hydride material wherein hydrogen is associated with the material.
The term "hydridable form" refers to a form of the metal hydride
material wherein the material is capable of becoming associated
with hydrogen.
[0110] The low temperature metal hydride material is metal hydride
material characterized by an absorption plateau pressure (PA.sub.L)
and a desorption plateau pressure (PD.sub.L). The high temperature
metal hydride material is metal hydride material characterized by
an absorption plateau pressure (PA.sub.H) and a desorption plateau
pressure (PD.sub.H). At a given temperature within the operational
range of the heat pump 10, PA.sub.L is greater than PA.sub.H. Also,
at a given temperature within the operational range of the heat
pump 10, PD.sub.L is greater than PD.sub.H. Each of the low
temperature metal hydride material and the high temperature metal
hydride material includes a hydrided form and a hydridable form. In
the hydrided form, hydrogen is associated with the metal hydride
material for example, by way of dissolution, ionic bonding,
covalent bonding, or by way of being present in a complex material
(e.g. sodium alanate). In the hydridable form, the metal hydride
material is capable of becoming associated with hydrogen.
[0111] It is understood that "low temperature metal hydride
material" can include a homogeneous or an inhomogeneous combination
of more than one distinct substance, and that such distinct
substance can be any of a hydrided or hydridable metal, an alloy of
a hydrided or hydridable metal, a compound of hydrided or
hydridable metal, or a hydrided or hydridable form of a complex
metal hydride. Also, it is understood that "high temperature metal
hydride material" can include more than one distinct substance, and
that such distinct substance can be any of a hydrided or hydridable
metal, an alloy of a hydrided or hydridable metal, a compound of a
hydrided or hydridable metal, or a hydrided or hydridable form of a
complex metal hydride. In these cases each of the substances of the
low temperature metal hydride material must have PA.sub.L greater
than PA.sub.H for each substance of the high temperature metal
hydride material, and must also have PD.sub.L greater than PD.sub.H
for each substance of the high temperature metal hydride material.
Similarly, each of the substances of the high temperature metal
hydride material must have PA.sub.H less than PA.sub.L for each
substance of the low temperature metal hydride material, and also
must have PD.sub.H less than PD.sub.L for each substance of the low
temperature metal hydride material.
[0112] In one embodiment, for example, each of the high temperature
metal hydride material and the low temperature metal hydride
material is disproportionation resistant. Disproportionation
describes the dissociation of a metal hydride material into its
constituent elements and/or hydrides of the constituent elements.
Disproportionation resistance means that the metal hydride material
may disproportionate over the design life of the heat pump in which
the metal hydride material is used, but that the extent of
disproportionation is not so significant such that the metal
hydride material appreciably loses its reversible hydriding
properties over such design life so as to adversely affect the
normal functioning of the heat pump.
[0113] It is preferable that excess low temperature metal hydride
material is used, relative to the high temperature metal hydride
material. Hydrogen pressure at high temperatures such as 1000
degrees F. can become excessive, and it is generally desirable to
maintain hydrogen pressure at about 700 psig. This can be
maintained by using slightly more low temperature metal hydride
material in the tube than is normally needed. This improves the
likelihood that, during the recharge cycle, all of the hydrogen
desorbed by the high temperature metal hydride material will have
sufficient low temperature metal hydride material available for
absorption. Preferably, the maximum storage capacity of the total
amount of low temperature metal hydride material in the tube
(vessel) is 1% to 10% greater than the maximum storage capacity of
the total amount of high temperature metal hydride material in the
tube (vessel). More preferably, it is 3% to 10% greater. Even more
preferably, it is 5% to 10% greater.
[0114] FIG. 9A (MHAC recharging mode) shows that when the high
temperature metal hydride material (right hand side of tube) is
heated with hot exhaust heat, hydrogen is driven out of the high
temperature metal hydride material and flows through the tube to
the low temperature metal hydride material located in the left hand
section of the tube. As the hydrogen enters the low temperature
metal hydride material, heat is generated. This generated heat is
removed by the ambient air flowing past the outside of the
tube.
[0115] FIG. 9B shows the MHAC cooling mode. Here, ambient air is
now flowing past the high temperature metal hydride material
section (right side). This cools down the material which allows the
hydrogen gas to flow back from the low temperature metal hydride
material. As this hydrogen leaves the low temperature metal hydride
material, cooling is generated. The heat removed from the low
temperature metal hydride material is supplied by the car's
interior air stream that is flowing past this left hand section of
the tube.
[0116] The air conditioner will house 712 of these individual small
tubes. These 712 tubes are split into two equal "beds" of about 356
tubes each. FIG. 10 shows the basic staggered tube pattern for each
bed. The split tube beds allow one bed to be recharged while the
other bed is producing cooling, therefore, continuous cooling is
generated by the MHAC.
[0117] FIG. 11 shows the basic 2 bed metal hydride heat exchanger
layout for this multi-tube design for the bench top prototype. The
top metal hydride bed is separated from the bottom bed by about a
0.5 inch clearance. The metal hydride tubes are held in place at
substantially the midpoint by the ss/ceramic wall.
[0118] FIG. 12 is the component layout as viewed from the top half
of the MHAC. This figure shows the conceptual placement of all
components of the top half of the MHAC.
[0119] FIG. 13 is an almost identical drawing for the bottom half
of the MHAC.
[0120] In this respect, in one embodiment, there is provided a
metal hydride heat pump 10 comprising a first compartment and a
second compartment. The first compartment includes a first gas
inlet configured for fluid communication with a first gas outlet.
The second compartment includes a second gas inlet configured for
fluid communication with a second gas outlet.
[0121] For the metal hydride heat pump 10, a plurality of metal
hydride vessels is provided, wherein each of the vessels is mounted
to and disposed within each of the first and second
compartments.
[0122] Each of the vessels contains at least a hydrided form of a
low temperature metal hydride material, a hydridable form of a high
temperature metal hydride material, and gaseous hydrogen, wherein
the hydridable form of a high temperature metal hydride material is
in fluid communication with the hydrided form of the low
temperature metal hydride material such that heat can be
transferred from (a) gas flowing through the first compartment to
(b) the hydrided form of a low temperature metal hydride material,
so as to effect desorption of hydrogen from the hydrided form of a
low temperature metal hydride material. The hydridable form of a
high temperature metal hydride material is configured to absorb the
desorbed hydrogen and generate heat upon the absorption such that
the generated heat can be transferred to gas flowing through the
second compartment. Each of the vessels has an external surface
area, and defines an internal volume for containing at least the
hydrided form of a low temperature metal hydride material, the
hydridable form of a high temperature metal hydride material, and
gaseous hydrogen, wherein a ratio of the external surface area to
the internal volume is greater than 45 inches.sup.2 per cubic
inch.
[0123] In one embodiment, each of the vessels extends between the
first and second compartments, and also extends into each of the
first and second compartments. The low temperature metal hydride
material is contained in a portion of the internal volume of each
vessel disposed in the first compartment, and the high temperature
metal hydride material is contained in a portion of the internal
volume of each vessel disposed in the second compartment.
[0124] In one embodiment, the internal volume of the vessel
contains an amount of metal hydride material consisting essentially
of (i) an amount of a hydrided and/or a hydridable form of a low
temperature metal hydride material, and (ii) an amount of a
hydrided and/or a hydridable form of a high temperature metal
hydride material, and wherein the amount of a hydrided and/or a
hydridable form of a low temperature metal hydride material is
substantially disposed in a portion of the internal volume of the
vessel disposed in the first compartment, and wherein the amount of
a hydrided and/or a hydridable form of a high temperature metal
hydride material is substantially disposed in a portion of the
internal volume of the vessel disposed in the second
compartment.
[0125] In this context, "consisting essentially of" means that
other materials may or may not be present in the internal volume.
If present, these other materials may be present as impurities
introduced as by-products during processing or from raw materials.
These other materials are present in amounts which are not
sufficiently significant to effect the desired properties of the
respective metal hydride materials imparted to the heat pump during
operation (cooling, regeneration) of the heat pump 10 incorporating
these metal hydride materials.
[0126] The term "substantially disposed" means that small,
insignificant amounts of the hydrogen storage materials may be
present outside of the respective internal volume portions
described above, so long as heat pump 10 operation (cooling,
regeneration) is not significantly detrimentally affected.
[0127] The amount of a hydrided and/or a hydridable form of a low
temperature metal hydride material has a first maximum hydrogen
storage capacity (the maximum amount of hydrogen which can be
absorbed by the amount of the low temperature metal hydride
material), and wherein the amount of a hydrided and/or a hydridable
form of a high temperature metal hydride material has a second
maximum hydrogen storage capacity (which is the maximum amount of
hydrogen which can be absorbed by the amount of the high
temperature hydrogen storage material), such that the first maximum
hydrogen storage capacity is 1% to 10% greater than the second
maximum hydrogen storage capacity. Preferably, the first maximum
hydrogen storage capacity is 3% to 10% greater than the second
maximum hydrogen storage capacity. Even more preferably, the first
maximum hydrogen storage capacity is 5% to 10% greater than the
second maximum hydrogen storage capacity.
[0128] The following is a list of all of these components needed
for the operation and instrumentation of the unit.
1 Exhaust Gas Simulation & Instrumentation Components Item F1
Exhaust gas simulation fan/blower. This fan will be variac
controlled and is ducted for use in both top and bottom metal
hydride (MH) beds. Item H1 Electrical resistance heating element,
variac controlled to provide the required waste heat simulation.
Item G1 Hot exhaust inlet gate valve to the high temperature metal
hydride material in the top MH bed. Item G9 Hot exhaust inlet gate
valve to the high temperature metal hydride material in the bottom
MH bed. Item G6 Hot exhaust outlet gate valve from the high
temperature metal hydride material section of the top MH bed. Item
G14 Hot exhaust outlet gate valve from the high temperature metal
hydride material section of the bottom MH bed. Item AFM1 "Exhaust
Gas" air flow meter located upstream of the exhaust gas heating
element. Analog output read by a computer data acquisition system
using "Labtech NOTEBOOK" software. Item TC1 Fast response
chromal/aluma thermocouple for measuring the exhaust gas
temperatures flowing into the high temperature metal hydride
material section of the top MH bed (analog signal fed into the
computer/NOTEBOOK system). Item TC9 Thermocouple, hot exhaust gas
inlet to the high temperature metal hydride material section of the
bottom MH bed. Item TC6 Thermocouple, hot exhaust gas outlet from
the high temperature metal hydride material section of the top MH
bed. Item TC14 Thermocouple, hot exhaust gas outlet from the high
temperature metal hydride material section of the bottom MH
bed.
[0129]
2 Ambient Cooling System Item F2 Ambient fan/blower, variac
controlled, ducted to provide ambient air flow to the four needed
regions. Item H2 Electrical resistance heating element, variac
controlled, to provide heating of ambient air up to 110.degree. F.,
for simulation of a hot summer day. Item G2 Ambient air inlet gate
valve to the high temperature metal hydride material in the top
bed. Item G3 Ambient air inlet gate valve to the low temperature
alloy in the top bed. Item G5 Ambient air outlet gate valve from
the high temperature metal hydride material in the top bed. Item G8
Ambient air outlet gate valve from the low temperature metal
hydride material in the top bed. Item G10 Ambient air inlet gate
valve into the high temperature metal hydride material tubes in the
bottom MH bed. Item G11 Ambient air inlet gate valve into the low
temperature metal hydride material tubes in the bottom MH bed. Item
G13 Ambient air outlet gate valve from the high temperature metal
hydride material tubes in the bottom MH bed. Item G16 Ambient air
outlet gate valve from the low temperature alloy tubes on the
bottom MH bed. Item AFM2 Air flow meter located before the fan in
the ambient air inlet duct. Analog output into computer/NOTEBOOK
data system. Item TC2 Thermocouple, ambient air inlet to high
temperature tubes on top bed. Item TC3 Thermocouple, ambient air
inlet to low temperature tubes on top bed. Item TC5 Thermocouple,
ambient air outlet from high temperature tubes on top bed. Item TC8
Thermocouple, ambient air outlet from low temperature tubes on top
bed. Item TC10 Thermocouple, ambient air inlet to high temperature
tubes on bottom bed. Item TC11 Thermocouple, ambient air inlet to
low temperature tubes on the bottom bed. Item TC13 Thermocouple,
ambient air outlet to high temperature tubes on bottom bed. Item
TC16 Thermocouple, ambient air outlet to low temperature tubes on
bottom bed.
[0130]
3 Interior Car Air System Item F3 Interior car air fan/blower,
variac controlled, ducted to provide air flow to either the top or
bottom MH beds. Item G4 Interior car air gate valve that lets air
flow into the low temperature metal hydride material tubes in the
top MH bed. Item G7 Interior car air gate valve that lets air flow
out of the low temperature metal hydride material tube section of
the top MH bed. Item G12 Interior car air gate valve that lets air
flow into the low temperature metal hydride material tubes in the
bottom MH bed. Item G15 Interior car air gate valve that lets air
flow out of the low temperature metal hydride material tube section
of the bottom MH bed. Item AFM3 Air flow meter measuring the air
flow into the interior car inlet air flow duct. Item TC4
Thermocouple, interior car air into the low temperature metal
hydride material tubes in the top MH bed. Item TC7 Thermocouple,
interior car air leaving the low temperature metal hydride material
tube section of the top MH bed. Item TC12 Thermocouple, interior
car air entering the low temperature metal hydride material tube
section of the bottom MH bed. Item TC15 Thermocouple, interior car
air leaving the low temperature metal hydride material section of
the bottom MH bed. NOTE: All air flow meter and thermocouple data
will be recorded via computer/"Labtech" NOTEBOOK software or
equivalent.
[0131] Gate Valve Control
[0132] FIGS. 14 and 15 show how operation and control of all of the
inlet gate valves (G1, G2, G3, G4, G9, G10, G11, G12) will be
accomplished with one actuation mechanism, a single acting
pneumatic piston. In FIG. 14, the gate valves are positioned such
that the top NH bed is in the cooling mode while the bottom MH bed
is in the regeneration mode. After the time for a 1/2 cycle times
out, the piston is energized and the gates will shift to the
position shown in FIG. 15. In this new position, the bottom MH bed
will be producing cooling while the top MH bed is being
regenerated.
[0133] In a like manner, all of the gate valves (G5, G6, G7, G8,
G13, G14, G15, G16) controlling the outlet air flow will be
controlled by a single pneumatic piston. This configuration will
provide the delayed switching of the outlet air flow paths needed
to provide sensible heat recovery.
[0134] In one embodiment, the heat pump 10 is designed to produce
6000 BTU per hour of cooling at a temperature of at least 47 F
using a hot air source (e.g. exhaust) at 1000 F following at 1
lbm/min air flow, with an ambient temperature of 120 F or less
(with 3% relative humidity).
[0135] Although the disclosure describes and illustrates preferred
embodiments of the invention, it is to be understood that the
invention is not limited to these particular embodiments. Many
variations and modifications may occur to those skilled in the art
within the scope of the invention. For definition of the invention,
reference is to be made to the appended claims.
* * * * *