U.S. patent application number 11/592556 was filed with the patent office on 2007-05-10 for apparatus and method for the conversion of thermal energy sources including solar energy.
This patent application is currently assigned to MeV Technology, Inc.. Invention is credited to Michael D. Strathman.
Application Number | 20070101989 11/592556 |
Document ID | / |
Family ID | 38002498 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070101989 |
Kind Code |
A1 |
Strathman; Michael D. |
May 10, 2007 |
Apparatus and method for the conversion of thermal energy sources
including solar energy
Abstract
Systems and methods to efficiently utilize thermal energy such
as solar energy, geothermal energy, waste-heat energy, bio-mass
combustion energy, or other equivalent forms of energy, convert the
thermal energy to another useful form of energy, such as
electricity or mechanical work using a thermodynamic cycle in which
a working fluid medium may be expanded in a constant pressure
environment to move a storage medium comprising another fluid,
slurry or mass to a higher potential energy level, from which the
storage medium may be released through a generator or the like to
produce another form of energy.
Inventors: |
Strathman; Michael D.; (San
Jose, CA) |
Correspondence
Address: |
LAW OFFICES OF BARRY N. YOUNG
260 SHERIDAN AVENUE
SUITE 410
PALO ALTO
CA
94306-2047
US
|
Assignee: |
MeV Technology, Inc.
|
Family ID: |
38002498 |
Appl. No.: |
11/592556 |
Filed: |
November 3, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60735056 |
Nov 8, 2005 |
|
|
|
60737682 |
Nov 17, 2005 |
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Current U.S.
Class: |
126/636 |
Current CPC
Class: |
F28D 2020/006 20130101;
Y02E 10/46 20130101; F01K 27/00 20130101; F01K 13/00 20130101; F24S
10/95 20180501; F01K 27/005 20130101; F03G 6/003 20130101; Y02E
10/44 20130101 |
Class at
Publication: |
126/636 |
International
Class: |
F24J 2/32 20060101
F24J002/32 |
Claims
1. A method of converting thermal energy, comprising: supplying
thermal energy to a working medium to cause expansion of at least a
portion of the working medium at substantially constant pressure;
imparting energy to a storage medium using said expansion of the
working medium to change the energy state of the storage medium
from a low potential energy to a higher potential energy; and
removing thermal energy from the working medium to return said
working medium to a non-expanded state while maintaining said
substantially constant pressure.
2. The method of claim 1, wherein said supplying comprises
supplying solar energy to said working medium, and said removing
comprising transferring heat from said working medium to an energy
sink.
3. The method of claim 2, wherein said supplying comprises passing
said working medium through a solar collector during daylight
hours, and said removing comprises cooling the working medium in a
condenser during nighttime hours.
4. The method of claim 1, wherein said working medium comprises a
working fluid, and said supplying comprises expanding said working
fluid to a gas in a container having a changing volume so as to
maintain the gas at said substantially constant pressure.
5. The method of claim 4, wherein said supplying comprises
supplying additional thermal energy to the gas to increase the
enthalpy of the gas.
6. The method of claim 4, wherein said removing thermal energy from
said working medium comprises using said removed thermal energy to
preheat another working medium in another changing volume container
of a pixelated system to promote expansion of said other working
medium.
7. The method of claim 4, wherein said working fluid is selected
from the group consisting of acetone, alcohol, water, various water
solutions, ammonia and water solutions, carbon dioxide, liquefied
natural gas (LNG), chloro-fluorocarbon (CFC) refrigerants R-410A,
R-22, R-32, R-125, R-407C, R-134A, and HCFC refrigerants.
8. The method of claim 4, wherein said removing thermal energy
comprises cooling the expanded working fluid while reducing the
volume of said container so as to maintain said substantially
constant pressure within said container.
9. The method of claim 4, wherein said imparting energy to said
storage medium comprises applying energy to said storage medium
using the changing volume of said container.
10. The method of claim 1, wherein said converting comprising
supplying at least a portion of the higher potential energy storage
medium to a prime mover at a lower potential energy level to
convert said higher potential energy to another form of energy
using said prime mover.
11. The method of claim 10, wherein said prime mover comprises a
generator, and said other form of energy comprises electricity.
12. The method of claim 10, wherein said prime mover comprises a
compressor in a refrigeration system, and said other form of energy
is used to produce a cryogenic fluid.
13. The method of claim 1, wherein said imparting energy to said
storage medium comprises displacing said storage medium to an
elevated height.
14. The method of claim 13, wherein said storage medium comprises a
fluid, and said displacing comprises pumping said fluid to a
reservoir at said elevated height.
15. A method of converting thermal energy to another form,
comprising: supplying thermal energy to a working fluid in a
plurality of container assemblies having changeable volumes so as
to cause expansion to a gas at a substantially constant pressure of
at least a portion of said working fluid in some of said plurality
of container assemblies; removing thermal energy from the gas in
one or more of said container assemblies to condense said gas back
to said working fluid while maintaining said substantially constant
pressure; supplying a portion of said removed thermal energy to
working fluid in other ones of said container assemblies to preheat
the working fluid in said other ones of said container assemblies
to promote expansion of the working fluid therein to a gas; and
imparting energy to a storage medium using said expansion of
working fluid to a gas to change the energy state of said storage
medium to a high energy level.
16. The method of claim 15, wherein said supplying thermal energy
comprises supplying solar energy from a plurality of solar
collectors, at least one solar collector being associated with one
or more of said container assemblies; and said removing thermal
energy from said gas comprises condensing said gas back to said
working fluid using a plurality of condensers, at least one
condenser being associated with one or more of said container
assemblies.
17. The method of claim 16, wherein said pluralities of solar
collectors, container assemblies and condensers are dispersed over
a landscape, and wherein said imparting energy to said storage
medium comprises transporting said storage medium to a storage
reservoir at an elevated level above said pluralities of solar
collectors, container assemblies and condensers.
18. The method of claim 17 further comprising supplying at least a
portion of said storage medium from said reservoir to a prime mover
at a lower level to convert a portion of the high energy of said
storage medium to another form of energy from the prime mover.
19. The method of claim 18 further comprising returning storage
medium from said low level to said container assemblies to maintain
said substantially constant pressure on said working fluid.
20. The method of claim 16, wherein said supplying solar energy
comprises supplying heat to the working fluid during daylight
hours, and said removing of thermal energy comprises condensing
said gas during nighttime hours.
21. The method of claim 15, wherein said storage medium is selected
from the group comprising fluids, slurries, and solid masses.
22. Apparatus for converting thermal energy, comprising: a solar
collector for supplying solar energy to an expansion medium
circulating therethrough; a containment assembly having first and
second chambers with changeable volumes, said solar energy causing
expansion to a gas at substantially constant pressure of said
expansion medium from said solar collector within the first
chamber, the second chamber of said containment assembly containing
a storage medium, and said changing volumes imparting energy to the
storage medium to move the storage medium to a high potential
energy reservoir; a condenser for removing heat energy from said
gas from said first chamber, while maintaining said substantially
constant pressure, to convert the gas back to said expansion
medium; and a prime mover for converting energy from said storage
medium in said high potential energy reservoir to another form upon
said storage medium moving to a low potential energy reservoir.
23. The apparatus of claim 22, wherein said containment assembly
comprises a container having a moveable separator therein dividing
the container into said first and second chambers, the volumes of
said chambers changing in relation to the movement of said moveable
separator.
24. The apparatus of claim 23, wherein said expansion medium and
said storage medium respectively comprise an expansion fluid and a
storage fluid, and said moveable separator comprises a layer of
non-miscible fluid that moves in response to pressure changes
between the first and second chambers to change the volumes of said
chambers.
25. The apparatus of claim 24, wherein the expansion of said
expansion fluid to said gas in the first chamber increases the
volume of the first chamber and decreases the volume of the second
chamber and exert pressure on said storage fluid in the second
chamber to displace said storage fluid to said high potential
energy reservoir.
26. The apparatus of claim 23, wherein said solar collector
comprises a fractal array of a plurality of solar collector units
arranged in collector groups, and a transport system connecting
said plurality of solar collector units for conveying expansion
medium through said units.
27. The apparatus of claim 26, wherein there are pluralities of
containment assemblies and condensers connected to said fractal
array of solar collector units to form a pixelized energy
conversion system, one or more of said containment assemblies,
condensers and collector units being associated together to form
corresponding pluralities of energy generator assemblies of said
system.
28. The apparatus of claim 22, wherein said energy conversion units
of said system are dispersed across a landscape, and said high
potential energy and said low potential energy reservoirs comprise
lakes.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
patent Application No. 60/735,056, filed Nov. 8, 2005, and U.S.
provisional patent Application No. 60/737,682, filed Nov. 17, 2005,
the disclosures of which are hereby incorporated by reference
herein.
TECHNICAL FIELD
[0002] The invention relates generally to energy conversion systems
and methods, and more particularly to the conversion of solar and
similar forms of heat energy to other forms of energy.
BACKGROUND
[0003] There are several sources of relatively abundant, relatively
inexpensive low density thermal energy, such as solar energy,
geothermal energy, waste-heat energy, and equivalent types of low
energy density heat energy. Conversion of this thermal energy to
other forms of more useful energy, while desirable to meet today's
increasing energy demands and costs and because of environmental
reasons, has not been widely used because it has been relatively
expensive and inefficient. Solar energy has a relatively low power
density, typically providing an average of 4-6 kilowatts per square
meter per day for a given flat surface collector area in the
continental USA, and conventional approaches to increase energy
production have focused on the use of very large arrays of mirrors
or lens systems to concentrate the photon energy of solar
radiation, which are problematic.
[0004] The problems with very large arrays include the installation
and land cost, vulnerability to high winds, dust and sand damage to
mirrors and lenses, and the traditional maintenance costs for both
tracking systems and the lens/mirror systems. Mirror and/or lens
systems are also susceptible to degradation over time, and the
tracking equipment to keep the mirror and/or lens properly
positioned in correspondence with the movement of the sun is
complex and costly to maintain.
[0005] Conventional generation of electricity from solar energy has
also had several serious problems. One common method to generate
electricity from solar energy is the use of photovoltaic cells
("PV"). However, conventional PV systems typically use less than
30% of the solar light frequency spectrum, that is photons having a
wavelength above that needed to create hole-electron pairs in a PV
cell. Therefore only a fraction of the total solar energy is
converted to electricity, and the efficiency of converting solar
energy into usable power from photovoltaic cells is fairly low,
requiring either very large surface areas or solar energy
concentrators. The photovoltaic cells also degrade over time and
lose most of their DC electricity production efficiency, typically
there is a significant decrease in output after 20 years or less.
Since most electrical power is AC, inverters are required to
convert the DC electricity from the photovoltaic cells to AC
electricity, and these electrical inverters have relatively short
mean times between failures, typically requiring repair within five
years or less. In a current study of energy usage in California,
for example, only about 0.5% of the useable energy comes from solar
energy, as the cost of a solar PV KWH of electricity is on the
order of 10 times greater than that from fossil fuel.
[0006] An alternative to photovoltaic systems is to utilize
thermally powered heat engines operating on various thermodynamic
cycles (e.g., an organic Rankine or other similar cycle). Thermally
powered engines can generally use fluids to both absorb the heat
from a heat source (e.g., solar energy, geothermal energy,
waste-heat energy, bio-mass combustion, and other such types of
energy) to create a gas, and use high pressure gas to drive some
sort of mechanical device or expander. The fluids can be a single
fluid, or a mixture of two or more fluids such as a binary solution
of ammonia and water, or the like. However, such systems have not
been found to be cost effective for large scale use. Because of the
generally low temperature differential between the hot side of an
engine and a condenser, conventional thermal power engines suffer
from low efficiency in energy conversion, expensive equipment and
materials, unreliability for long-term operation, and costly
maintenance.
[0007] There are three main types of passive thermal energy
collector systems used for collecting thermal energy (e.g., solar
energy, or an equivalent). Low-temperature collectors (unglazed)
normally operate at up to approximately 18 F.degree. (10 C.degree.)
above ambient temperature, and are most often used for heating
swimming pools. Often, the pool water is colder than the air, and
insulating the collector would be counter-productive.
Low-temperature collectors are typically extruded from
polypropylene or other polymers with UV stabilizers. Flow passages
for the pool water are molded directly into the absorber plate, and
pool water is circulated through the collectors with the pool
filter circulation pump. Swimming pool heaters typically cost from
$10 to $40/ft.sup.2 (based on 2004 prices).
[0008] Mid-temperature collectors are usually flat plates insulated
by a low-iron cover glass and fiberglass or poly-isocyanurate
insulation. Reflection and absorption of sunlight in the cover
glass reduces the efficiency at low temperature differences, but
the glass is required to retain heat at higher temperatures. A
copper absorber plate with copper tubes welded to the fins is
typically used. In order to reduce radiant losses from the
collector, the absorber plate is often treated with a black nickel
selective surface, which has a relatively high absorptivity in the
short-wave solar spectrum, but a relatively low-emissivity in the
long-wave thermal spectrum. Mid-temperature collectors typically
range in cost from $90 to $120/ft.sup.2 of collector area (based on
2004 prices).
[0009] High-temperature collectors utilize evacuated tubes around a
receiver tube to provide high levels of insulation and often use
focusing curved mirrors to concentrate sunlight. High temperature
collectors are normally used for absorption cooling or electricity
generation, but are also sometimes used for mid-temperature
applications, such as commercial or institutional water heating as
well. Evacuated tube collectors themselves typically cost about
$75/ft.sup.2, but use of curved mirrors and economies of scale get
this cost down for large system sizes to a relatively low cost of
$40-70/ft.sup.2 of collector area (based on 2004 prices).
[0010] A need exists for a higher efficiency, lower cost systems
for thermal energy conversion and utilization, in general, and
especially for the utilization of solar energy that avoid the
foregoing and other problems of known approaches. There is a need
for systems that do not require expensive equipment, materials, or
maintenance, are relatively stable and non-degradable in long-term
operation, and have good efficiency. It is to these ends that the
present invention is directed.
SUMMARY OF THE INVENTION
[0011] The invention affords a system and method which use the
phase transformation of a working expansion medium (e.g., a liquid,
or a solid such as dry ice) into a gas during heat absorption.
During expansion, the enthalpy of the system is the physical work
done plus the work of the latent heat of fusion which is used to
change the liquid to a gas. This increases the internal energy of
the system, which may be recovered during a cooling period, such as
night time, when the gas is cooled and returned to the liquid state
and the heat evolved is emitted into deep space on the dark side of
the planet which is not facing the sun. This cycle creates a change
in the solar cross section of the planet, as all energy that is
captured by phase transformation from liquid to gas over a given
absorption area is released into space by black body radiation
during the night time operations. Energy systems in accordance with
the invention, if utilized on a large scale, can efficiently
produce energy such as electricity or other forms of useful power
and power storage, as well as help to reduce global warming.
[0012] Advantageously, the invention may provide a heat energy
conversion system that is coupled to the normal varying, more or
less sinusoidal, energy field that characterizes the daily solar
heat cycle due to the daytime exposure to the sun and the
subsequent nighttime exposure to a cold heat sink (e.g., deep
space). This cycle comprises a heat energy source (or photons which
can be converted to heat) and an energy sink. The energy source may
be the sun (in the case of the planet earth) and the energy sink
may comprise interstellar space (deep space on the side of the
earth not facing the sun). A portion of heat energy absorbed during
daylight may go directly into generating external work via a prime
mover, and the rest of the absorbed heat may be used to raise the
enthalpy (or internal energy) of the system. The energy that goes
into driving an expansion medium, i.e., a working fluid or working
liquid, to the gas phase raises the internal energy of the system.
This energy can be stored in the system and can be emitted via
black body radiation to deep space on during nighttime operations.
Heat is not absorbed by the system, rather it passes through the
system, is absorbed in the liquid-to-gas phase transformation, and
then is emitted in the transformation of the expansion medium from
gas to liquid.
[0013] The invention may utilize, in part, the fact that when an
expansion fluid makes the transformation from a liquid to a gas,
the volume occupied by the expansion fluid may increase by several,
typically about three; orders of magnitude (1000 times larger). The
liquid-to-gas transformation is done with the liquid at a high
pressure, as will be shown later on the pressure vapor curve for
the expansion fluid. Heat is supplied by the sun to drive the
temperature of the expansion fluid to the boiling point and then
into the liquid-to-gas transformation. As the volume of gas
increases, this volume change can be used to displace another
working medium, referred to as a storage medium, to a higher
potential energy. Once the storage medium is at the higher
potential energy it can either be used directly being returned to a
lower potential through a prime mover which extracts energy from
the storage medium, or it can be stored at the higher potential
energy level for use at some later time.
[0014] The invention can be used to pump a working medium, such as
water, to a higher potential energy and transport it over a hill
such as the California aqueduct passing over the Grapevine area of
California, where it can be available for different uses. In this
case the working medium (water) can be replaced on the pumping side
by water flowing in the California aqueduct from Northern
California to Southern California
[0015] The invention also affords a pixelized collection system to
allow for more efficient use of the absorbed heat energy, and
enables use of cells that have been fully expunged of the working
medium by the gaseous expansion medium to heat the liquid expansion
medium for subsequent cells in the pixelization collector, thus
increasing the overall efficiency of the system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates a block diagram of a conventional Rankine
cycle engine, as used in conventional solar energy
applications;
[0017] FIG. 2 illustrates a block diagram of a modified Rankine
cycle in accordance with one embodiment of the invention;
[0018] FIG. 3 illustrates a vapor pressure curve of an expansion
medium, such as ammonia, that may be used in the invention;
[0019] FIG. 4 is a block diagram of a thermal energy system in
accordance with a first embodiment of the invention;
[0020] FIG. 5 is a more detailed block diagram of the system shown
in FIG. 4;
[0021] FIG. 6 is a diagrammatic view of an implementation of a
thermal energy system in accordance with the invention;
[0022] FIG. 6A is a diagrammatic view of a thermal energy system in
accordance with an alternative embodiment of the invention where
energy production is only required during day light hours and high
potential energy storage is not used;
[0023] FIG. 7 is a flowchart of a method in accordance with the
embodiment of FIGS. 4-6, 6A for converting thermal energy to
another useful form of energy;
[0024] FIG. 8 is a flowchart of another method in accordance with
the invention for converting thermal energy to another form of
energy in a pixilation system of the type illustrated in FIGS.
15A-C;
[0025] FIG. 9 illustrates a flowchart of a method of generating
energy, in accordance with another embodiment of the invention;
[0026] FIG. 10 illustrates a flowchart of a method of generating
electricity, in accordance with a further embodiment of the
invention;
[0027] FIG. 11 is a diagrammatic view of the solar energy
generation system shown in FIG. 6;
[0028] FIG. 12 is a diagrammatic view of a solar pumping system in
accordance with the invention;
[0029] FIG. 13 is a cross-sectional view of a containment assembly
that may be used in the systems of the invention;
[0030] FIG. 14 is a diagrammatic view of another embodiment of a
containment assembly, partially broken away, that may be used in
the systems of the invention;
[0031] FIG. 15A is a block diagram of a pixelized energy collection
system in accordance with another embodiment of the invention.
[0032] FIG. 15B is a more detailed diagrammatic view of a pixelized
energy generation system in accordance with another embodiment of
the invention having two or more interconnected energy generator
assemblies;
[0033] FIG. 15C illustrates a diagrammatic view of an alternative
embodiment of the system of FIG. 15B;
[0034] FIG. 16 is a flowchart of a method of converting thermal
energy to another useful form of energy from a plurality of
interconnected energy generator assemblies; and
[0035] FIG. 17 illustrates a fractal solar energy collector array
that may be employed for the pixelized collection of energy in
accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Embodiments of the invention can be constructed from
commercially available components. In all of the embodiments
disclosed below, various different materials may be used for the
chambers, reservoirs, and piping, including but not limited to
various plastics, rubbers, resins, ceramics, cements, and metals,
or other equivalent man-made materials. The collector may be a
low-temperature collector, a mid-temperature collector, a
high-temperature collector, or a combination of different types of
collectors.
[0037] The invention employs a working medium, also referred to as
an expansion medium, and a storage medium. The expansion medium and
storage medium of the invention preferably comprise fluids, as will
be explained. These two fluids may be the same, or one fluid may be
used as the expansion medium and a second different fluid may be
used as the storage medium. Materials that may be utilized for the
working (expansion) fluid and storage fluid include, but are not
limited to, acetone, alcohol, water, various water solutions,
ammonia and water solutions (e.g., such as an 80% ammonia and 20%
water solution, or equivalents), liquefied natural gas (LNG),
chloro-fluorocarbon (CFC) refrigerants (e.g., R-410A, R-22, R-32,
R-125, R-407C, R-134A), the equivalent hydrogenated CFC (HCFC)
refrigerants, ammonia, carbon dioxide, or other non-aqueous fluids
having similar vapor pressure curves. Preferred criteria for
selecting the expansion and storage media will be explained in
connection with FIG. 3. Additionally, as will also be explained,
the storage medium may also comprise a slurry, a powder, or a solid
mass that can be transformed to a higher potential energy.
[0038] The invention affords a system for generating useful
mechanical power, for generating chemical energy or for supplying
chemical fuels (e.g. chemical fuels generated from electrolysis,
e.g., hydrogen and oxygen, or equivalents), or connected to one or
more electrical generators for producing either AC or DC
electricity. The invention may also be used to generate cryogenic
fluids such as liquid nitrogen. Some embodiments of the invention
can accommodate variations in the heights available for utilizing a
storage medium, if necessary.
[0039] The invention has some similarities to a Rankine cycle
engine and to a Sterling engine, but differs in several significant
ways. First, the invention may utilize a substantially constant
pressure and a changing volume of a working medium, e.g., a fluid,
the volume increasing during an expansion phase and decreasing
during a contraction phase, to produce useful work. Work may be
extracted by a corresponding increase in the volume of a
displacement chamber, for example, caused by the conversion of a
liquid expansion medium to a gas. This expansion ratio of gas to
liquid may be on the order of 1000 times the volume in the gas
phase verses the liquid phase.
[0040] FIG. 1 illustrates a block diagram of a conventional Rankine
cycle engine. As shown, there is a boiler 102 connected with a pipe
169 to a turbine 112, which is connected with an output pipe 167 to
a condenser 124. The condenser is connected with an output pipe 165
to a feed pump 106 that supplies boiler 102 by an output pipe 104.
The expansion medium in a conventional Rankine cycle engine is
typically water.
[0041] The turbine 112 (e.g., a steam turbine, water turbine, or
generator) utilizes a substantially isentropic expansion; the
condenser 124 utilizes a substantially isobaric heat rejection; the
feed pump 106 utilizes a substantially isentropic compression; and
the boiler 102 utilizes a substantially isobaric heat supply. Heat
103 is supplied to the boiler 102 and heat 105 is rejected by the
condenser 124. The work output 107 is from the turbine and the work
input 108 is to the feed pump 106. The net work produced by this
engine is the difference of the work output 107 and the work input
108.
[0042] In a conventional Rankine cycle engine, work is extracted by
expanding a high pressure gas (and volume) and reducing the gas
pressure during this expansion cycle. Unlike a Rankine cycle, as
will be explained, the invention does not have to expand the gas to
a lower pressure to extract work. It may reduce the gas temperature
and volume, and heat a liquid expansion medium to near its boiling
point. The expansion of the gas may be used to displace a storage
medium from a low potential energy ("LE") to a high potential
energy ("HE"). As the storage medium is returned to the lower
potential energy, it may pass through a prime mover (e.g., a
turbine, generator, pump, mechanical power take off) or other
system that uses the energy change to produce work. Thus, while the
work extracted is from the expansion of the working medium from
liquid to gas, the invention does not expand the gas to a lower
pressure as is done in a conventional Rankine cycle.
[0043] In addition, as mentioned above, the invention may utilize
the fact that work is required for the transformation of a liquid
to a gas, (the latent heat of fusion or internal energy of the
system), and physical work may be extracted as the liquid expands,
typically about 1000 times, as it goes through the phase
transformation at a high pressure. This expansion of volume may be
used to generate physical work, as in a collector/expansion system.
If the collector/expansion system is composed of a plurality of
small chambers, then when a given chamber has all of its storage
medium (the "storage medium" may be a fluid such as water, a slurry
or powder, or a physical mass that can be lifted to a higher
potential energy) displaced by the expansion medium, that chamber
can be isolated from the main system's storage media, and the heat
trapped in that smaller chamber can be used to raise an expansion
fluid temperature to just below the liquid-to-gas transformation
temperature. The invention may employ several fully displaced
chambers so that all of the heat energy that was used to raise the
first chamber liquid to the boiling point can be recovered from the
hot working medium gas.
[0044] As the temperature of the gas is lowered, the chamber can
then be partially refilled with the storage media and then reheated
to force more storage media to a higher potential. This is similar
to the reheat cycle in an advanced reheat Rankine cycle engine or
somewhat like that of a Sterling engine.
[0045] Thus, the invention differs substantially from a
conventional Rankine cycle in the fact that the gas that is evolved
from the expansion medium is not expanded in an increased volume
and the temperature is not lowered. Rather, the pressure can be
retained at a constant value and the volume may be expanded to
contain the increased gas volume due to the liquid-to-gas
transformation of the expansion media. The increased volume may be
used to move the working medium to a higher potential energy, from
which it may be run through a prime mover (turbine, expander,
pressurizer, etc. ) to produce work as it moves to a lower
potential energy. The working medium may then be returned to its
lowest potential energy as it is used to pressurize the gaseous
expansion medium and help (with cooling) to drive the phase
transformation of the expansion media from the gas phase to the
liquid phase. The invention may comprise a binary system that
includes an expansion medium which is separate from the working
media, and the expansion medium drives the working media to a
higher potential energy. In addition the invention does not require
a conventional feed water pump as does a conventional Rankine cycle
engine.
[0046] FIG. 2 illustrates a block diagram of a thermodynamic cycle
of a modified Rankine cycle engine in accordance with the
invention. Referring to FIG. 2 there is a reservoir 110, connected
with an output pipe 169, to a turbine (e.g., steam turbine, water
turbine, generator, or equivalent) 112 with an output pipe 167
witch is connected to a condenser 124, connected with an output
pipe 165 to the containment assembly 130, may be connected by a
pipe 163 to the reservoir 110. There is no feed pump 106 and no
output pipe 104, as in a conventional Rankine cycle engine. Heat
103 may be supplied to the containment assembly 130, and heat 105
is rejected by the condenser 124. The work output 107 from this
engine is from the prime mover 112.
[0047] The prime mover 112 (e.g., a steam turbine, water turbine,
generator, or equivalent) may utilize a substantially isentropic
process, the condenser 124 may utilize a substantially isobaric
heat rejection, and the reservoir 110 in one embodiment may be
filled with a storage medium (not shown) moved by pressure provided
by an expansion medium (not shown). Several possible materials
could be utilized for the expansion medium and storage medium,
including acetone, alcohol, water, various water solutions, ammonia
and water solutions (e.g., such as an 80% ammonia and 20% water
solution, or equivalents), liquefied natural gas (LNG),
chloro-fluorocarbon (CFC) refrigerants (e.g., R-410A, R-22, R-32,
R-125, R-407C, R-134A), the equivalent HCFC refrigerants, ammonia,
carbon dioxide, or other non-aqueous fluids having substantially
similar vapor pressure curves. Substantially the same fluid may be
used for both the expansion medium and the storage medium. The
expansion medium in the modified Rankine cycle engine can be any
fluid having a suitable vapor pressure curve, for example, as shown
in FIG. 3 (and described below).
[0048] FIG. 3 illustrates a vapor pressure curve of an exemplary
expansion medium, ammonia, that may be used in the invention. The
vertical axis 302 indicates the vapor pressure of the expansion
medium, and the vapor pressure curve 304 of the expansion medium is
shown plotted, between the vertical axis 302 and the horizontal
axis 306 indicating the temperature in degrees Kelvin and the
horizontal axis 308 indicating the temperature in degrees
Celsius.
[0049] Suitable expansion medium for the invention is preferably
selected to have a high pressure at the high temperature side of
the thermodynamic cycle, and a fairly low pressure in the
condensation side of the cycle. Two suitable fluids are ammonia and
carbon dioxide which have pressures of about 40-50 bar at a working
temperature of about 30-40.degree. C. above ambient, and also have
a good pressure, on the order of 10 bar, for the condensation of
gas back to liquid. Also important is the latent heat of fusion vs.
the expansion factor. CO.sub.2 may have a slight advantage in
efficiency as compared to ammonia in this regard.
[0050] The process of evaporation in a closed chamber will proceed
until there are as many molecules returning to the liquid as there
are escaping. At this point the vapor is said to be saturated, and
the pressure of that vapor is called the saturated vapor pressure.
Since the molecular kinetic energy is greater at higher
temperature, more molecules can escape the surface and the
saturated vapor pressure is correspondingly higher. If the liquid
is open to the air, then the vapor pressure is seen as a partial
pressure along with the other constituents of the air. The
temperature at which the vapor pressure is equal to the atmospheric
pressure is called the boiling point. The phase change of a fluid
from a liquid to a vapor (and the reverse process) can be utilized
in multiple ways by the invention, as described below.
[0051] FIG. 4 illustrates a block diagram of a system in accordance
with a first embodiment of the invention to utilize thermal energy.
The system includes a high potential energy reservoir 110, a
turbine 112, a low potential energy reservoir 114, and a
containment assembly 130 containing the storage media 129. The
system also includes a thermal energy collector 120 connected to an
expansion medium reservoir 126, which receives the expansion medium
127 from a condenser 124, which is connected to the containment
assembly 130. The expansion medium 127 is capable of undergoing a
phase change from a liquid to a vapor upon the application of
thermal energy, and disposed to circulate through the thermal
energy collector 120, the containment assembly 130 and the
condenser 124. The storage media 129 circulates through the high
potential energy reservoir 110, the turbine 112, the low potential
energy reservoir 114, and the containment assembly 130 as a result
of displacement in the containment assembly 130 caused by the
vaporization of the expansion medium 129. The thermal energy
collector 120 can collect heat from one or more sources (e.g.,
solar energy, geothermal energy, waste-heat energy, bio-mass
combustion, and other equivalent types of energy).
[0052] FIG. 5 illustrates in more detail the system shown in FIG.
4. FIG. 5 shows, for example, more details of the containment
assembly, and includes a plurality of valves that may be used to
control the system. As shown, containment assembly 130 may have a
containment assembly interior 116 containing the storage medium
(fluid) 129, and a displacement chamber 122 containing the working
vapor 128.
[0053] Valve 143 may control the flow in the pipe between the high
potential energy reservoir 110 and the containment assembly
interior 116 in the containment assembly 130. Valve 142 may control
the flow in the pipe between the low potential energy reservoir 114
and the containment assembly interior 116 in the containment
assembly 130. Valve 149 may control the flow in the pipe between
the low potential energy reservoir 114 and the containment assembly
interior 116 in the containment assembly 130. Valve 141 may control
the flow in the pipe between the turbine 112 and the low potential
energy reservoir 114. Valves 146 and 148 may control the flow of
expansion medium (working fluid) 127 between the thermal energy
collector 120 and the expansion medium (working fluid) reservoir
126. Valve 147 may control the flow of working fluid 127 between
the condenser 124 and the working fluid reservoir 126; and valve
145 may control the flow of working fluid vapor 128 between the
condenser 124 and the displacement chamber 122 in the containment
assembly 130.
[0054] FIG. 6 illustrates diagrammatically an implementation of the
system of FIGS. 4 and 5 in accordance with a preferred embodiment
of the invention. As will be described, the invention may be
implemented as a solar energy system using natural or man-made
geographical features, such as lakes, as reservoirs. FIG. 6
illustrates lakes as reservoirs. However, it may be appreciated
that the reservoirs may take other forms, and that the invention
may be implemented in other contexts.
[0055] As shown in FIG. 6, the system may include a high potential
energy reservoir 110 (such as lake 1), a turbine 112, a low
potential energy reservoir 114 (lake 2), and a containment assembly
130 (pump chamber) containing the storage medium 129 (e.g., water)
in the containment assembly interior 116. The system also includes
a thermal energy collector 120 (e.g., an evaporator) connected to
an expansion medium reservoir 126 (fluid tank), which receives
expansion medium 127 from a condenser 124, which is connected to
the containment assembly 130. The expansion medium, preferably a
fluid, is capable of undergoing a phase change from a liquid to a
vapor 128 (gas) in displacement chamber 122 upon the application of
thermal energy (e.g., from the sun 600) and disposed to circulate
through the thermal energy collector 120, the containment assembly
130 and the condenser 124. The storage medium (water) 129
circulates through the high potential energy reservoir 110, the
turbine or prime mover 112, the low potential energy reservoir 114,
and the containment assembly 130 as a result of displacement caused
by the vaporization of the expansion medium 129 in the displacement
chamber 122. Valves v1, v2, v3, v4, v5, v6, v7, and v8, which are
analogous to various ones of the valves shown in FIG. 5, control
the system and will be described in detail in connection with FIGS.
11 and 12. The sun may be the thermal energy source in this
embodiment, but in other embodiments other heat sources may be used
alone or in combination to supply the thermal energy.
[0056] Generating electrical energy in large quantities for an
electrical power grid is not trivial, especially for AC electricity
power grids. Large amounts of electricity needed by an electrical
power grid cannot be stored as electricity in conventional systems,
although it may be stored in another form. Therefore, the energy
taken from an electrical power supply grid must always be equal to
the energy being delivered by the electrical power plants. If this
were not the case, the frequency and voltage of the supply grid
would deviate from standard values.
[0057] Pumped storage plants address this problem by storing
electrical energy as potential energy. They pump water to an upper
reservoir at times of surplus energy on an electrical supply
grid-typically, at night. This potential energy is then released
through a hydro-electrical generator at times of high demand. Use
of hydroelectric turbines allows direct energy conversion to AC
electrical power. Electrical DC to AC conversion (used in many
conventional solar energy systems) is not required, thereby
significantly reducing the complexity, reliability problems, and
cost of construction and maintenance, as compared to conventional
DC electricity supply systems.
[0058] FIG. 6A illustrates a modification of the system of FIG. 6
which is used for power generation during daylight operations only.
In this system, the flow of the working medium (water) is not
supplied to a high potential energy reservoir, such as lake 1, but
is directly input into the inlet of the prime mover or turbine 112
to generate power, such as electricity.
[0059] FIG. 7 is a flowchart of a method of converting thermal
energy to another useful form of energy, in accordance with the
embodiment of the invention shown in FIGS. 4-5. Referring to FIG.
7, the method begins at 702. At 704, thermal energy is absorbed
into an expansion medium, such as a working fluid. At 706, at least
a portion of the expansion medium is vaporized to exert pressure on
a storage medium, such as a storage fluid, to displace at least a
portion of the storage fluid from a lower potential energy state to
a higher potential energy state. This corresponds, for example, to
transporting the storage fluid from chamber 116 of containment
assembly 130 of the system of FIG. 6 to the reservoir 110. At 708,
the portion of the expansion fluid that was vaporized is
substantially condensed, corresponding, for example, to condensing
a portion of the expansion gas 128 from chamber 122 back to a
liquid in condenser 124. At 710, a portion of the storage fluid
displaced to a higher potential energy state (to reservoir 110,
FIG. 6) is supplied to at least one turbine to produce a second
form of energy. At 712, substantially the portion of storage fluid
from the at least one turbine is supplied to at least one lower
potential energy state. The method ends at operation 714.
[0060] FIG. 8 illustrates a flowchart of another method in
accordance with the invention for converting thermal energy to
another form of energy in a pixelized system (such as will be
described in more detail in connection with FIGS. 15A-C) which
combines the contributions of multiple energy collector/generator
assemblies. The method contemplates a system that uses of one or
more expansion and storage media, e.g., fluids, as well as multiple
separate components for some system components, such as thermal
energy collectors, containment assemblies, condensers, prime
movers, etc. The method begins in operation 802. At 804, at least
one expansion medium (working fluid) is stored in a working fluid
reservoir. At 806, the at least one working fluid is communicated
to at least one thermal energy collector to vaporize a portion of
the at least one working fluid. At 808, the vaporized portion of at
least one working fluid is communicated into at least one
containment assembly, where the portion of the vaporized working
fluid exerts pressure on at least one storage medium (fluid) in the
at least one containment assembly to transport the at least one
storage fluid to at least one higher potential energy reservoir. At
810, the portion of vaporized at least one expansion fluid from the
at least one containment assembly is communicated to at least one
condenser, where the vaporized portion of the expansion fluid is
condensed and communicated to at least one expansion medium
reservoir. At 812, at least one storage fluid from the least one
higher potential energy reservoir is communicated to at least one
turbine generator, where another form of energy, e.g., electricity,
is generated, and at 814 the at least one storage fluid is
communicated from the at least one generator to at least one lower
potential energy reservoir. At 816, the at least one storage media
is communicated from the at least one lower potential energy
reservoir to the at least one containment assembly, and the method
ends at 818.
[0061] FIG. 9 is a flowchart of a method of generating energy that
is somewhat similar to that shown in FIG. 7, except that the method
is more precisely focused on FIG. 6. The method begins at 902. At
904, at least one expansion medium (working fluid) is stored in an
expansion medium reservoir. At 906, the at least one working fluid
is communicated to an energy collector. At 908, the working fluid
in the energy collector is vaporized and communicated into a
containment assembly at 912, where the vaporized working fluid
exerts pressure on a storage fluid in the containment assembly to
transport the storage fluid to a high potential reservoir. At 912,
the vaporized working fluid from the containment assembly is
communicated to a condenser where it is condensed. At 914, the
expansion medium from the condenser is communicated to the
expansion medium reservoir. Operation 916 is next and includes
supplying the storage fluid from the high potential reservoir to a
generator where energy is generated. At 918, the storage fluid from
the generator is communicated to a low potential reservoir, and at
920 is communicated to the containment assembly. The method ends at
922.
[0062] FIG. 10 illustrates a method of generating electricity, in
accordance with the invention. The method begins at 1002. At 1006,
working fluid stored in a reservoir is transported using gravity to
a solar collector where it is vaporized by solar energy. At 1008,
the vaporized working fluid is communicated into a containment
assembly, where the vaporized working fluid exerts pressure on a
storage fluid in the containment assembly which transports the
storage fluid to a high potential reservoir. At 1010, the vaporized
working fluid is communicated from the containment assembly to a
condenser where it is condensed by heat transfer to the ambient
environment. Operation 1012 is next and includes using gravity to
transport the working fluid from the condenser to the working fluid
reservoir. At 1014, the storage fluid supplied from the high
potential reservoir to an electrical generator, whereby electricity
is generated. At 1016, the storage fluid is exhausted from the
electrical generator to a low potential reservoir, and transported
using gravity to the containment assembly at 1016. The method ends
at 1020.
[0063] FIG. 11 is diagrammatic view of an embodiment of an energy
generation system 100 corresponding to that shown in FIGS. 4-6. A
reservoir 126 holds an expansion medium, i.e., a working fluid, 127
and may be connected by a pipe 166 to a collector 120. A valve 146
may control the flow of expansion medium 127 between reservoir 126
and collector 120. Flow of expansion medium 127 from reservoir 126
to collector 120 may be induced by gravity or pumping. Collector
120 is configured to increase the temperature of the expansion
medium flowing through it when exposed a source of energy, such as
the sun. Once the temperature of the expansion medium 127 in
collector 120 reaches a critical temperature, it undergoes a phase
change from a liquid to a vapor. The gaseous expansion medium vapor
128 occupies a larger volume than the liquid expansion medium 127,
and it may be communicated through pipe 164 into a displacement
chamber 122 contained in the interior 116 of a containment assembly
130. A valve 144 may control the communication of vapor 128 from
collector 120 to displacement chamber 122. Significantly, the
displacement chamber 122 may be constructed, as with bellows or the
like, to increase its volume in response to increasing pressure
within the displacement chamber so as to maintain the pressure in
the chamber substantially constant. Accordingly, as the vapor 128
expands into displacement chamber 122, the displacement chamber 122
increases in volume. Pressure exerted by liquid working fluid in
chamber 116 on the vapor in expandable displacement chamber 122
causes the vapor to flow through a pressure equalization line 1.68
to maintain approximately equal pressure between collector 120 and
reservoir 126. A valve 148 may control the communication between
reservoir 126 and collector 120.
[0064] When displacement chamber 122 has increased by a
predetermined volume, .DELTA.V1, expansion medium vapor 128 may be
conducted through a pipe 165 to a condenser 124. A valve 146 may
control flow of the vapor 128 between the displacement chamber and
the condenser. In condenser 124, the expansion medium vapor 128
undergoes a phase change from a vapor 128 to a liquid 127. In
undergoing this phase change from vapor to liquid, the expansion
medium vapor 128 decreases by a predetermined volume .DELTA.V2 in
the condenser, and displacement chamber 122 also decreases by about
the same predetermined volume .DELTA.V2. The expansion liquid 127
may flow to reservoir 126 through a pipe 167 between condenser 124
and reservoir 126 may be controlled by a valve 147. The flow of
condensed expansion liquid 127 from condenser 124 to reservoir 126
may be induced by gravity or pumping.
[0065] Containment assembly 130 also contains a storage medium,
e.g., a fluid, 129 in the containment assembly interior 116. As
displacement chamber 122 expands inside of containment assembly
interior 116, pressure on storage medium 129 causes it to be
displaced and communicated by a pipe 163 to a high potential energy
reservoir 110. A valve 143 may control the communication of storage
medium 129 between the containment assembly interior 116 and the
reservoir 110. Subsequently, the storage medium 129 may then be
communicated from the high potential energy reservoir 110 through a
pipe 169 to a prime mover 112, such as a generator, a turbine, or
other power producing device. A valve 149 may control the
communication of storage medium between the high potential
reservoir 110 and prime mover 112. Storage medium 129 may then be
communicated through a pipe 161 from the prime mover to a low
potential reservoir 114. A valve 141 may control the communication
of the storage medium between the prime mover and the low potential
reservoir. Storage medium 129 may then be communicated through a
pipe 162 from the low potential reservoir 114 to the interior 116
of containment assembly 130. A valve 142 may control this flow.
[0066] As discussed above, the flow of expansion medium 127 from
reservoir 126 to collector 120 may be induced by gravity or
pumping. Placing the reservoir 126 at a higher gravitational
potential than the collector 120, i.e., at a higher height than the
collector, enables the expansion medium 127 to flow down under the
influence of gravity from the reservoir 126 to the collector 120.
Pressure equalization line 168 prevents a vacuum from disrupting
the flow of expansion medium between reservoir 126 and collector
120 by equalizing the pressure between reservoir 126 and collector
120.
[0067] High potential reservoir 110 is preferably placed at an
elevation or height Hi above the containment assembly 130 so that
the work required to move the storage medium 129 from containment
assembly 130 to the high potential reservoir 110 is imparted to the
storage medium as potential energy. At such elevation H1, the
storage medium in the high potential reservoir exerts a pressure P1
through pipe 163 at containment assembly 130. The pressure P1 is
determined by the height H1 of high potential reservoir 110 above
containment assembly 130. For example, when the storage medium 129
is water, the pressure P1 is about 0.43 pounds per square inch for
each foot of height H1. For a height H1 of about 1300 feet, the
pressure at the containment assembly 130 will be about 560 pounds
per square inch (560 psi).
[0068] The minimum amount of work, W, required to raise a
predetermined mass M1 of storage medium 129 from the containment
assembly 130 to the high potential reservoir 110 is simply the mass
M1, times the height H1, times gravitational acceleration g, or:
W=M1*g*H1 (1)
[0069] The storage media 129 in high potential reservoir has a
potential energy equal to the work W. This potential energy is
available for conversion to some other form of energy, for example
electricity. For example, a portion of this potential energy may be
used to operate the prime mover 112. The prime mover 112 may be
placed a distance H2 below the high potential reservoir 110, so
that the amount of potential energy E available to operate
generator 112 may be calculated as the predetermined mass M2 of the
storage medium released to the prime mover 112, times the distance
H2, times g or: E=M2*g*H2 (2)
[0070] While a generator is an example of a prime mover that may be
used, other forms of energy conversion apparatus may also be
utilized to advantage. For example, mechanical energy may be
extracted from the potential energy E in a variety of ways well
known in the mechanical and hydraulic arts.
[0071] Moreover, storage medium 129 could also be used to raise a
mass other than the storage medium 129 to the high potential
reservoir 110. For example the storage medium could be employed to
provide power other types of mechanical and hydraulic apparatus
adapted to lifting a discrete object, or solid mass (such as rock
or grain, for example) to the high potential reservoir.
[0072] As indicated above, the temperature of expansion medium 127
rises in collector 120 until the critical temperature of the
expansion medium is reached. The critical temperature of a fluid is
the temperature at which the fluid will undergo a phase change from
fluid to vapor at the ambient pressure. For example, the critical
temperature of a common refrigerant R-410A is about 150 degrees F.
at an ambient pressure of 550-600 psi. The ambient pressure in the
interior 116 of containment assembly 130 may be the pressure P1, as
determined by the elevation H1 of the high potential reservoir 110
above the containment assembly 130. As indicated, when elevation H1
is about 1300 feet the pressure P1 at the containment assembly
interior will be about 560 psi and the R-410A would undergo a phase
change from fluid to vapor at about 150 degrees F. At the critical
temperature, additional heat energy (for example heat energy from
solar energy) applied to the collector 120, causes additional
molecules of the expansion medium to undergo the transition from
fluid to vapor without increasing the temperature of the expansion
medium above the critical temperature. R-410A is given by way of
example as a suitable expansion medium, but many other types of
expansion media may be used, as previously described.
[0073] As discussed above, when displacement chamber 122 has
expanded to a predetermined volume, the expansion medium vapor 128
in displacement chamber 122 may be conducted through a pipe 165 to
a condenser 124. Condenser 124 may be maintained at a temperature
substantially below the temperature of the collector 120 during the
expansion of the expansion medium fluid into a vapor. At a lower
temperature, the expansion medium will condense at a substantially
lower pressure. Storage medium 129 in low potential reservoir 114
may be used to displace expansion medium vapor 128 from
displacement chamber 122 through pipe 165 into condenser 124. A
pressure P2 may be exerted through pipe 162 to compress
displacement chamber 122 and exert a pressure P2 on the expansion
vapor therein. The pressure P2 may be determined by the elevation
H3 of the low potential reservoir 114 above the containment
assembly 130. For example, when elevation H3 is about 230 feet,
pressure P2 may be about 100 psi. At about 90-120 psi, R-410A vapor
will condense at about 50 degrees F., for example.
[0074] The available work, Wa, from energy system 100 is the change
in volume .DELTA.V1 times the pressure P1 minus the change in
volume .DELTA.V2 times the pressure P2 or:
Wa=P1*.DELTA.V1-P2*.DELTA.V2 (3) When .DELTA.V1=.DELTA.V2, the
available work is: Wa=.DELTA.V1(P1-P2) (4)
[0075] As discussed above, the flow of expansion medium 127 from
condenser 124 to reservoir 126 may be induced by gravity or pumping
means. Placing the condenser 124 at a higher gravitational
potential than reservoir 126, that is above the reservoir 126,
enables the expansion medium 127 to flow down under the influence
of gravity from the condenser to the reservoir 126.
[0076] In an example of operation of the energy generator system
100, solar energy may be used during the day to cause expansion of
an expansion fluid 127 to an expansion vapor 128. The expansion
vapor may be used in the containment assembly 130 to pump water
during a pumping step up to high potential reservoir 110, for
example a lake at a high level. The water may then generate
electricity by running back down through a turbine during an energy
generation step to low potential reservoir 114, for example to a
lake at a lower level. At night, when the condenser 124 has been
cooled by giving off energy in the form of radiation to the sky,
water in the low potential reservoir 114 may then be used to
recompress the expansion vapor 128 into an expansion fluid 127 in
the condenser 124. In this case, energy may be input into the
system 100 during the daytime from a high energy source, e.g.,
solar radiation. Energy may be output from the system 100 during
the nighttime into a low energy sink, as by radiation to a black
body (e.g., into space). The energy source is the sun, and the
energy sink is space. The energy generator system 100 extracts
useful work or electricity by moderating the flow of energy from
the high-energy source to the low energy source.
[0077] Table 1 below illustrates examples of valve states for the
system 100 of FIG. 11 during a pumping phase, an energy generation
phase and a recompression phase (either warm or cold). During
conversion of heat energy to potential energy (the pumping phase),
valves 142, 145, and 147 may be closed while valves 143, 144,146,
and 148 may be open. During the day, solar energy heats the
collector 120 and the expansion medium 127, for example R-410,
expands to an expansion vapor at about 150 degrees F. at a pressure
of about 550-600 psi. Expanded vapor 128 flows through pipe 164 and
open valve 144 into displacement chamber 122. Valve 145 may be
closed, thus forcing displacement chamber 122 to expand inside
containment assembly 130. As expansion medium 127 is used up by
expansion into vapor 128, the expansion medium 127 may be replaced
from reservoir 126 through pipe 166 by opening valve 146. Placing
reservoir 126 above collector 120 enables gravitational flow of
expansion medium 127 downhill from reservoir 126 to collector 120
through valve 146. Valve 148 permits pressure equalization through
pipe 168 between collector 120 and reservoir 126, thus enabling
flow from reservoir 126 to collector 120. Expansion of the
displacement chamber 122 displaces the storage medium 129, for
example water. The water is forced up hill to the high potential
reservoir 110 through pipe 163 and valve 143 by the expansion of
the working fluid to vapor. Valves 143 and 146 may be partially
opened to control pressures in the containment assembly 130, and
may be adjusted to optimize the work extracted in lifting water to
the high elevation lake 110. Once in the lake (high potential
reservoir 110), the water may be released through valves 141, 149,
as desired, to generate electricity. Thus the generation step may
be independent of, or coincident with, either the pumping step or
the recompression step. Valves 141 and 149 may be opened or closed
as the generator may or may not be operated during the pumping
step. The following Table 1 illustrates the valve states during
different phases of operation of system 100. TABLE-US-00001 TABLE 1
Expansion medium/vapor Storage Media valves state 144 145 146 147
148 141 142 143 149 Pumping step 1 0 1 0 1 X 0 1 X Energy
generation step X X X X X 1 X X 1 Recompression step (warm) 0 1 0 1
0 X 1 0 X Recompression step (cold) 0 1 X 1 X X 1 0 X state: 1 =
open; 0 = closed; X = open or closed
[0078] During the energy generation phase, as illustrated in Table
1 the expansion medium, water for example, may be released through
pipe 169 by opening valve 149 and valve 141. Valve 149 may be
redundant but it is desirable because it permits retaining the
water in the lake with minimal pressure head on the generator 112.
Valves 142, 143, 144, 145, 146, 147, and 148 may be open or closed
during the energy generation step. The water may flow through
generator 112, for example, a turbine, to generate electricity.
Alternatively, the water may be used to perform other forms of
work. Open valve 141 permits water to flow through pipe 161 to low
potential reservoir 114, for example, a low level lake. The water
may be stored in the low potential reservoir until time for
recompression of the expansion medium vapor 128 back into the
expansion medium 127 during the recompression step.
[0079] During the recompression phase, as illustrated in Table 1,
valves 142,145, and 147 may be open, and valves 143 and 144 may be
closed. Valves 141 and 149 may be either open or closed. Valves 146
and 148 may be open or closed when the recompression step is
performed under cold conditions, that is when the temperature of
collector 120 is about the temperature of the condenser 124 or
lower. When recompression is done under warm conditions, that is
when the temperature of collector 120 is above the temperature of
condenser 124, then valve 146 and 148 are preferably closed.
Recompression may take place when the condenser 124 reaches a
substantially lower temperature than the pumping phase temperature,
for example, about 50 degrees F. At about 50 degrees F R-410A may
be recompressed at a pressure of about 90-120 psi. A pressure of
about 90-120 psi may be exerted by a pressure head of about 200
feet. Therefore, the low level reservoir may be located about 200
feet above the containment assembly 130. The recompression takes
place as water from the low potential reservoir 114 flows down to
the containment assembly 130 through pipe 162 and valve 142. The
water urges the expansion medium vapor 128 through pipe 165 and
valve 145 to the condenser 124. The condenser is preferably
maintained at about 50 degrees F. In the condenser the expansion
medium vapor 128 condenses to the expansion medium fluid 127.
Condensation of the expansion medium vapor 127 to the expansion
medium fluid 128 creates a low-pressure region in the condenser 124
that draws more expansion medium vapor 128 into condenser 124 for
condensation. Heat energy is released by the condensation
process.
[0080] The condenser 124 may dissipate this heat energy through a
number of methods. For example, the recompression may be conducted
at night when the ambient temperatures are substantially lower than
during the daylight hours. Such substantially lower temperature may
be sustained by radiation from the condenser into a black body,
such as a clear night sky, i.e., into space. The condenser may also
be placed in a body of water, such as a lake, for example. Such
bodies of water may be sized to afford a good sink and accept large
quantities of heat energy from the condenser 124, thus
advantageously maintaining the condenser 124 at a substantially
constant temperature. Moreover, bodies of water make excellent
radiators into the clear night sky. In accepting heat energy from
the condenser 124 and radiating it into a black body, such as
space, bodies of water act as heat conductors to conduct heat from
the condenser 124 to space. An example of a large body of water or
lake may be the low potential reservoir 114.
[0081] FIG. 12 is diagrammatic view of one embodiment of a solar
pumping system 200. The system of FIG. 12 may be substantially
similar to the system 100 of FIG. 11, except that instead of using
a storage medium or fluid 129, the system may be used to
communicate a working pump fluid 229, e.g., water, from a low
position reservoir 214 to a high position reservoir 210, where the
pump fluid may be stored or use, e.g., for irrigation, and the
system 200 does not have a return path through a prime mover 112
(and the associated components) for energy generation as does the
system 100 of FIG. 11.
[0082] The operation of the system 200 of FIG. 12 may be
substantially the same as that described above for the system 100
of FIG. 11. As with system 100, the pump fluid 229 may also provide
power to a mechanical and hydraulic apparatus, for example, to lift
a discrete object or a solid mass (such as rock or grain, for
example) to the location of high position reservoir 210.
[0083] Low position reservoir 214 may be any source of pump fluid
229 which it is desired to pump to a higher location. Preferably,
since pump fluid is not returned to low position reservoir 214, the
low position reservoir 214 may be a source of pump fluid that is
functionally unlimited, such as a lake, an aqueduct, or a
river.
[0084] The valve states during operation of the system 200 may be
the same as shown in Table 1, except that there are no valves 141
and 149 in system 200 since there is no return path from the high
position reservoir.
[0085] FIG. 13 is a diagrammatic view of a first embodiment of a
containment assembly 130 that may be employed in systems in
accordance with the invention. FIG. 13 illustrates the expansion
medium vapor 128 in the displacement chamber 122 separated from the
storage medium 129 by a piston 310. Piston 310 may be a mechanical
piston, as is well known in the mechanical arts, or a layer of
fluid adapted to form a barrier between storage medium 129 and
expansion medium vapor 128, the fluid being non-miscible with the
storage medium 129 and the expansion medium vapor 128. A suitable
fluid layer piston, where the storage medium 129 is water, is an
oil that is non-miscible with water.
[0086] As illustrated in Table 1 above, during the pumping step of
the cycle, valves 143 and 144 are open while 142 and 145 are
closed. Expansion medium vapor 128 may be admitted to the interior
122 of the displacement chamber at a higher pressure than the
pressure on the storage medium 129, and the storage medium is
displaced and exits through pipe 163 and valve 143. During the
recompression step, valves 143 and 144 may be closed while valves
142 and 145 may be open to control flow through pipes 162, 163,
164, and 165. Pressure from the low potential reservoir 114 drives
piston 310 against the expansion medium vapor 127 in displacement
chamber 122. Displacement chamber 122 decreases in volume, and the
expansion medium vapor 128 exits the displacement chamber through
pipe 165 and valve 145. As described above, the movable piston and
the operation of the containment assembly advantageously insures
that the expansion and recompression of the expansion medium is
accomplished at substantially constant pressure.
[0087] FIG. 14 is a diagrammatic view of another embodiment of a
containment assembly 130 that may be used in the invention. FIG. 14
illustrates the expansion medium vapor 128 in the displacement
chamber 122 which is separated from the storage medium 129 by a
moveable piston 310. As with FIG. 13, piston 310 may be a
mechanical piston or a layer of non-miscible fluid adapted to form
a barrier between storage medium and the expansion medium vapor.
The piston 310 separates the expansion medium vapor 128 from the
storage media 129 and preventing mixing of the fluid 129 with the
vapor 128. When piston 310 is a layer of fluid, such as oil, the
piston has the added advantage of being capable of sealing complex
or irregular interior surfaces of the containment assembly.
[0088] Tube 170 may communicate the storage medium 129 from the
containment chamber 130 through a single orifice in the containment
chamber wall to valves 142 and 143, thus preserving the structural
integrity of containment chamber 130. Similarly, tube 171 may
communicate the expansion medium vapor 128 to the containment
assembly through pipes 164 and 165 controlled by valves 144 and
145, respectively.
Pixelization of Energy Collection for Energy Concentration
[0089] Conventional thermal energy conversion systems typically
concentrate the thermal energy in one location so that one central
converter can transform the thermal energy into another useful form
of energy such as electricity. The invention advantageously enables
a different approach, referred to herein as "pixelization", whereby
multiple dispersed energy conversion systems (or portions thereof)
such as previously described may be combined into a single system
that effectively sums the individual contribution of each
individual system. Pixelization in accordance with the invention
may accomplished by moving storage media (e.g., water, or another
storage media) from point to point rather than by moving the
thermal energy to a central site. This movement of the storage
medium from many dispersed collectors to a central collection site,
for example, allows for the collected energy to be concentrated by
adding the output of multiple fluid pumps of lower capacity, and
reduces the need to transport heat over large distances to a
central evaporator. Multiple evaporators can be positioned close to
the solar collectors. Also, pixelization allows for the full
displacement of a given chamber's working medium by hot gaseous
expansion of the medium, and the use of the hot gaseous expansion
to preheat liquid expansion medium that will be boiled off
(converted to vapor, as described above) to evacuate other chambers
of their working medium. Using several chambers in sequence will
allow almost all of the heat energy that was used to raise
expansion medium in a first chamber to the boiling point to be
captured and reused, thus increasing system efficiency
substantially. Also, because the chambers that have been used for
heat exchange have a lower pressure, they can be partially refilled
with working medium and reheated to drive even more working medium
to a higher potential energy point.
[0090] FIG. 15A is a block diagram of a system for the pixelized
collection of energy, in accordance with the invention. A plurality
of energy generator assemblies 100'a-n may move a storage medium
through a manifold 510 to a high potential energy reservoir 110.
Moreover, the transformation of thermal energy to another form of
energy can be performed by multiple units at dispersed localized
locations, and the transformed energy (e.g., the movement of a
storage medium, such as water, to a higher elevation) from the
dispersed units may be transported and added together at one or
more other locations to take advantage of economies of scale in the
transformation of potential energy into electrical energy, or in
pumping or refrigeration applications.
[0091] A principal advantage with this system is that the losses
associated with the transportation of low heat differential masses
are minimized, and the savings are transformed into the increase in
potential energy of the storage medium. Individual pixelization
units can also be run using standard Rankine cycle pumps. Moreover,
standard Rankine cycle pumps can be used in a first group of
pixelization units, and modified Rankine cycle pumps of the
invention, such as shown in FIG. 2, can be used in a second group
of pixelization units and their energy contributions combined.
[0092] FIG. 15B is a diagrammatic view of an embodiment of a
pixelized energy generation system in accordance with the invention
that comprises a plurality of two or more interconnected energy
generator assemblies 100'a-n that have a common manifold 510 for
receiving and combining the pump storage media from the individual
generator assemblies 100'a-n. The energy generator assemblies
100'a-n may be placed in dispersed locations or collocated in an
array. Each of the energy generator assemblies 100'a-n produces a
partial contribution to the total combined energy from the group of
generator assemblies which is combined at the manifold 510 with the
partial contributions from other generator assemblies. The partial
energy generated by each of the energy generator assemblies 100'a-n
may be proportional to the area of sunlight striking the energy
generator assembly. The manifold 510 may communicate the combined
energy to a high potential reservoir 110 through a pipe 163, where
the contribution of each energy generator assembly 100'a-n may be
accumulated.
[0093] FIG. 15C is a diagrammatic illustration of an alternative
embodiment of an energy generation system similar to that shown in
FIG. 15B, except that instead of a common manifold, the partial
contributions of the individual energy generator assemblies 100'a-n
are separately communicated to the high position reservoir 110 by
separate lines 163a-n, each controlled by a corresponding valve
143a-n. The system of FIG. 15C is more appropriate where the
various energy generator assemblies 100'a-n are dispersed to
different locations, and it is more efficient to separately provide
storage media for the individual assemblies to the reservoir than
to combine the storage media in a common manifold as in FIG.
15B
[0094] As discussed above, in both of the embodiments of FIGS. 15B
and C, storage media 129 may released through a generator 112 to
flow to a low potential reservoir 114, and the storage media from
the low potential reservoir 114 through pipe 162 and distributed
through manifold 514 through valves 142a-n to energy assemblies
100'a-n. Thus, energy generator assemblies 100'a-n may
advantageously be a large number of small generator systems
distributed over a large area, and may be built on a small-scale
with the economy of large-scale generators and reservoirs. This
permits concentration of partial energy from many small energy
generator assemblies 100' composed of modest part sizes optimized
to exploit economies of mass production, and that may not even be
in line of sight of each other. For example, energy generator
assemblies 100'a-n that are separated by buildings or terrain such
as terrain including one or more hills or bluffs may still
contribute energy to the system through plumbing connected to the
reservoir 110. Thus, energy generator assemblies 100'a-n are
capable functioning in terrain where mirror systems for
concentrating solar energy might be impractical because the line of
sight is blocked. Moreover, energy generator assemblies 100'a-n
that are spread over a large or irregular area, beyond the
practical range of a lens concentrating system, may still
contribute substantial energy to the system through plumbing
connected to the reservoir 110.
[0095] FIG. 16 is a flowchart of a method of converting thermal
energy to another useful form of energy, in the systems of FIGS.
15A-C. The method begins at 1602. At 1604, thermal energy may be
absorbed into an expansion medium at a plurality of energy
generator assemblies. At 1606, at least a portion of the Expansion
medium may be vaporized to exert pressure on a storage medium to
displace at least a portion of the storage medium at the plurality
of energy generator assemblies. Operation 1608 is next and includes
condensing substantially the portion of the expansion medium that
was vaporized. At 1610, the displaced portion of the storage media
from the plurality of energy generator assemblies may be collected.
At 1612, the displaced portion of the storage medium displaced to a
higher potential energy state is supplied to power at least one
turbine to produce a second form of energy. At 1614, substantially
the portion of storage media from the at least one turbine is
supplied to a lower potential energy state. The method ends in
operation 1616.
[0096] FIG. 17 is a diagrammatic view of a fractal solar energy
collector array that may be used in the above systems for the
pixelized collection of energy. The fractal solar energy collector
1710 may comprise arrays of a plurality of solar energy collectors
1702, arranged in a fractal pattern of, for example, sixteen
collector groups 1704, arranged in a fractal pattern of, for
example, sixty-four collector groups 1706, all connected to a
fractal expansion medium transport system 1708.
[0097] A fractal solar energy collector array as shown in FIG. 17
may be advantageously dispersed across a landscape for the
pixelized collection of energy, and connected to natural or
man-made reservoirs or lakes for the storage and release of storage
medium through one or more generators, or in the case of pumping
systems, for the transport of water, for example, through aqueducts
or the like.
Refrigeration and Generation of Cryogenic Fluids
[0098] As described in the foregoing, the invention may use a prime
mover such as turbine or a generator to transform thermal energy to
a second form of energy. The turbine may comprise a compressor in a
refrigeration or air conditioning system, thus affording solar
refrigeration and air conditioning systems, or may be used as part
of a multiple stage refrigeration system to generate cryogenic
fluids (e.g., liquid nitrogen, liquid air, liquid oxygen, etc.).
The compressor can be a conventional closed-loop heat pump
arrangement to compress a gas which is allowed to expand at another
location and absorb thermal energy for the expansion to cool an
object (e.g., the inside of a refrigerator, or an equivalent
space). Cryogenic temperatures can be reached by a multiple stage
implementation of heat pumps, and the cryogenic fluids (e.g.,
liquid nitrogen, liquid oxygen, etc.) may be used locally or
transported to other locations for use in any of a variety of
different applications (e.g., transportation, energy generation,
various chemical processes, or equivalents).
[0099] As will be appreciated, while the invention has been
described with reference to preferred embodiments, various changes
in these embodiments may be made without departing from the spirit
and principles of the invention, the scope of which is defined in
the appended claims.
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