U.S. patent application number 10/667099 was filed with the patent office on 2004-03-25 for rankine cycle generation of electricity.
Invention is credited to Lawheed, Paul.
Application Number | 20040055300 10/667099 |
Document ID | / |
Family ID | 28039507 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040055300 |
Kind Code |
A1 |
Lawheed, Paul |
March 25, 2004 |
Rankine cycle generation of electricity
Abstract
Systems or combinations and methodology for converting solar
energy to electrical energy and thermal energy and for converting
the resultant thermal energy to electrical energy are disclosed.
Systems and methodology for conversion of low temperature thermal
energy, wherever obtained, to electrical energy using a Rankine
cycle mechanism to drive an electrical generator or do other work
in a cost effective way are also disclosed.
Inventors: |
Lawheed, Paul; (San Diego,
CA) |
Correspondence
Address: |
Mr. Lynn G. Foster
602 East 300 South
Salt Lake City
UT
84102
US
|
Family ID: |
28039507 |
Appl. No.: |
10/667099 |
Filed: |
September 19, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10667099 |
Sep 19, 2003 |
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10099069 |
Mar 14, 2002 |
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6672064 |
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Current U.S.
Class: |
60/641.8 |
Current CPC
Class: |
F01C 1/123 20130101;
F01C 3/00 20130101; Y02E 10/46 20130101; Y02B 10/20 20130101; F01K
3/185 20130101; Y02E 20/14 20130101; F03G 6/067 20130101; F05C
2253/20 20130101; Y02T 10/7072 20130101 |
Class at
Publication: |
060/641.8 |
International
Class: |
F03G 006/00; B60L
008/00; B60K 016/00 |
Claims
What is claimed and desired to be secured by Letters Patent is:
1. A method of using solar energy to generate primary and secondary
electricity comprising the acts of: directly converting solar
energy to electricity at a solar electric generator; cooling the
solar electric generator with a coolant; utilizing heat carried
away from the electric generator by the coolant to drive a Rankine
cycle generating system to also produce electricity.
2. A method according to claim 1 wherein the coolant is a liquid
and wherein the utilizing act comprises passing the heated coolant
as a liquid through a heat exchanger to elevate the temperature of
gas being passed through the heat exchanger which drives a Rankine
cycle mechanism to produce torque which in turn drives an
electricity producing-generator.
3. A method according to claim 2 wherein the gas comprises
steam.
4. A method according to claim 1 wherein the electricity produced
by the directly converting act is direct current electricity.
5. A method according to claim 4 further comprising the act of
converting the direct current electricity to alternating current
electricity.
6. A method according to claim 2 wherein the liquid coolant is
recirculated through the solar electric generator and the heat
exchanger.
7. A method according to claim 2 wherein the gas is cooled and
thereafter recirculated through the heat exchanger.
8. A method according to claim 2 wherein the gas is displaced
through a cooling device after passing through the Rankine cycle
mechanism and before being returned to the heat exchanger.
9. A method according to claim 2 wherein the liquid coolant
discharged from the solar generator has a relative low temperature
range below the vapor point and the gas is within a temperature
range of 80.degree. F. or less.
10. A method according to claim 2 wherein the gas is displaced into
the Rankine cycle mechanism at a pressure on the order of 15
psi.
11. A method of using liquid at a moderately elevated temperature
to do work comprising the acts of: displacing liquid at an elevated
temperature, below its vapor temperature through a liquid-gas heat
exchanger; displacing a gas through the liquid-gas heat exchange to
transfer heat from the liquid to the gas; displacing the gas to
rotate a Rankine cycle lobe-displacement mechanism to create
rotation of at least one output shaft; converting the output shaft
rotation to work.
12. A method according to claim 11 further comprising the act of
recirculating the gas through the heat exchanger and the Rankine
cycle mechanism.
13. A method according to claim 11 wherein the third displacing act
comprises rotating two output shafts and the converting act
comprises work derived from the rotation of two shafts.
14. A method according to claim 13 wherein the two output shafts
are geared together for common though opposite rotation.
15. A method according to claim 12 further comprising the act of
cooling the gas after it leaves the Rankine cycle mechanism and
before it returns to the heat exchanger.
16. A method according to claim 11 wherein the converting act
comprises driving an electric generator via shaft rotation to
obtain electricity.
17. A method of generating electricity by displacing a fluid at a
moderately elevated temperature comprising the acts of: introducing
the fluid at a temperature within a range of up to 100.degree. F.
and at an influent pressure within a range on the order of 15 psi
into a space between oppositely rotatable lobes respectively
mounted on interconnected shafts within a Rankine cycle mechanism;
applying the pressure of the fluid: (a) first predominantly against
one lobe to forcibly rotate that lobe in a first direction causing
the other lobe, through the interconnected shafts, to oppositely
rotate in a second direction and (b) second predominantly against
the other lobe to forcibly rotate the other lobe in the second
direction causing the one lobe, through the interconnected shafts,
to rotate in the first direction; driving an electric generator
with one or both shafts to create electricity.
18. A method according to claim 17 wherein the fluid is a gas.
19. A method according to claim 18 wherein the gas comprises
steam.
20. A method of generating electricity comprising the acts of:
impinging influent fluid under low pressure and at a moderately
elevated temperature on a continuous flow basis against a first
shaft-mounted lobe of a Rankine cycle mechanism to forcibly rotate
the first lobe and the shaft upon which the first lobe is mounted
in a first direction, a second shaft-mounted lobe being caused to
oppositely rotate in a second direction as a follower; thereafter
impinging the continuous flow influent fluid against the second
lobe to forcibly rotate the second lobe and the shaft upon which
the second lobe is mounted, the first lobe and the shaft upon which
the first lobe is mounted to rotate in the first direction as a
follower; generating electricity via shaft rotation derived from
the Rankine cycle mechanism.
21. A method according to claim 20 further comprising the act of
elevating the temperature of the fluid in a heat exchanger using a
liquid at a temperature below its boiling point.
22. A method of generating electricity using a Rankine cycle
mechanism comprising the acts of: impinging influent fluid having
an elevated temperature first against one lobe and then another
lobe to rotate the lobes in opposite directions and to turn at
least one output shaft; using the rotation of the at least one
output shaft to drive a generator by which electricity is
produced.
23. A system for using solar energy to co-generate primary and
secondary electricity comprising the acts of: a solar generator
which directly converts solar energy to electricity; a cooling unit
for cooling the solar electric generator with a coolant; a Rankine
cycle mechanism which utilizes heat derived from the coolant to
drive a generator to also produce electricity.
24. A system according to claim 23 wherein the coolant comprises a
liquid, the cooling unit comprises a heat exchanger by which the
elevated temperature of the liquid coolant increases the
temperature of a gas being passed through the heat exchanger, and
the Rankine cycle mechanism comprises at least one output shaft the
rotation of which drives the generator.
25. A system according to claim 24 wherein the gas comprises
steam.
26. A system according to claim 23 wherein the electricity produced
by the solar generator is direct current electricity.
27. A method according to claim 26 further comprising a direct
current-to-alternating current converter by which the direct
current electricity is transformed to alternating current
electricity.
28. A method according to claim 24 wherein the cooling unit
comprises a recirculator by which liquid coolant is continuously
recirculated through the solar electric generator and the heat
exchanger.
29. A system according to claim 24 wherein the cooling unit
comprises a recirculator by which the gas is continuously
recirculated through the heat exchanger and the Rankine cycle
mechanism.
30. A system according to claim 29 wherein the cooling unit further
comprises a second heat exchanger whereby the gas is continuously
displaced through the second heat exchanger after passing through
the Rankine cycle mechanism and before being returned to the first
heat exchanger.
31. A system according to claim 24 wherein the liquid coolant
discharged from the solar generator has a relative low temperature
range below its vapor temperature and the gas is within the
temperature range below the temperature of the liquid coolant.
32. A system according to claim 24 wherein the gas is displaced
into the Rankine cycle mechanism at a pressure of on the order of
15 psi.
33. A system for using liquid at a moderately elevated temperature
to do work comprising: liquid-gas heat exchange through which a
liquid at an elevated temperature below its vapor point is
displaced and through which a gas is displaced to transfer heat
from the liquid to the gas; a Rankine cycle lobe-displacement
mechanism using the gas passed therethrough, after discharge from
the heat exchanger, to rotate at least one output shaft; a device
driven by the shaft rotation to do work.
34. A system according to claim 33 further comprising a pump by
which wherein the gas is recirculated through the Rankine cycle
mechanism and the heat exchanger.
35. A system according to claim 34 further comprising a gas cooler
for cooling the gas after it leaves the Rankine cycle mechanism and
before it returns to the heat exchanger.
36. A system according to claim 33 wherein the Rankine cycle
mechanism comprises two oppositely rotated output shafts both of
which drive the work device.
37. A system according to claim 36 wherein the Rankine cycle
mechanism comprises two interconnected shaft-mounted, oppositely
rotating gears non-rotatably respectively connected to two output
shafts for common though opposite rotation.
38. A system according to claim 33 wherein the work device
comprises an electric generator turned by rotation of the at least
one shaft to obtain electricity.
39. A system for generating electricity by displacing a fluid at a
moderately elevated temperature comprising the acts of: a Rankine
cycle mechanism into which the fluid is introduced at a temperature
within a range on the order of 100.degree. F. or less and at a
pressure within a range of on the order of 15 psi into a space
between oppositely rotatable lobes respectively mounted on
interconnected shafts of the Rankine cycle mechanism; such that the
pressure of the fluid is: (a) first applied against one lobe to
forcibly rotate that lobe in a first direction causing the other
lobe, through the interconnected shafts, to oppositely rotate in a
second direction and (b) then is applied against the other lobe to
forcibly rotate the other lobe in the second direction causing the
one lobe, through the interconnected shafts, to rotate in the first
direction; an electric generator connected to one or both shafts to
create electricity.
40. A system according to claim 39 wherein the fluid is a gas.
41. A system according to claim 40 wherein the gas comprises
steam.
42. A system for generating electricity comprising: a Rankine cycle
mechanism which receives influent fluid under low pressure and a
moderately elevated temperature on a continuous flow basis such
that the fluid: (a) first against a first shaft-mounted lobe of the
Rankine cycle mechanism to forcibly rotate the first lobe and the
shaft upon which the first lobe is mounted in a first direction, a
second lobe shaft-mounted being caused by said rotation of the
first lobe to oppositely rotate in a second direction as a follower
and (b) thereafter against the second lobe to forcibly rotate the
second lobe and the shaft upon which the second lobe is mounted,
the first lobe and the shaft upon which the first lobe is mounted
being caused by said rotation of the second lobe to rotate in the
first direction as a follower; an electric generator connected to
one or both shafts to generate electricity due to shaft
rotation.
43. A system according to claim 42 further comprising a heat
exchanger by which the temperature of the fluid is elevated using a
liquid at a temperature below its boiling point before introduction
into the Rankine cycle mechanism.
44. A system for generating electricity comprising a Rankine cycle
mechanism comprising interconnected oppositely rotating shaft
mounted lobes such that influent fluid having an elevated
temperature is impinged first against one lobe and then the other
lobe to concurrently rotate the lobes in opposite directions to
turn the shafts and a generator rotated by one or both output
shafts to drive the generator to create electricity.
Description
RELATED APPLICATION
[0001] This application is related to copending U.S. patent
application Ser. No. 09/867,196, filed May 29, 2001 and entitled
CONVERSION OF SOLAR ENERGY, the contents of which are incorporated
herein by reference.
FIELD OF INVENTION
[0002] The present invention relates generally to the generation of
electricity and more particularly to: (a) solar generation of
electricity in combination with Rankine cycle generation of
electricity; and (b) use of a Rankine cycle mechanism to generate
electricity or do other work.
BACKGROUND
[0003] Solar energy is freely and daily available. It is a clean,
non-polluting source of energy. Providing a reliable, long term,
cost effective, efficient way of using sunlight to obtain
electrical and thermal power has long been an unsolved problem,
until the present invention.
[0004] It has been proposed that flat panel solar converters be
used to convert direct sunlight into thermal or electrical
energy.
[0005] Pedestal supported flat panels using direct sunlight to
generate electricity were part of the Solar One project.
[0006] A circular, but concave reflector mounted on a single column
or pedestal has been proposed. This approach was used on the
Soleras water desalination project in Saudi Arabia and on the Solar
Two project in Dagget, Calif.
[0007] Fixed position concave reflectors placed in an array and
positioned in side by side rows on an incline have ben proposed.
See U.S. Pat. No. 4,202,322. Such an installation was made at the
Federal Correctional Institution at Phoenix, Ariz.
[0008] Tiltable elongated concave reflector assemblies have been
utilized, such as the one at Barstow, Calif., owned by FPL Energy
SEGS VIII and IX.
[0009] Solar Systems comprising bidirectionally controlled Fresnel
lens and solar cell assemblies, utilizing direct sunlight, have
been proposed. See, U.S. Pat. No. 4,649,899, for example. Also see,
U.S. Pat. No. 4,245,153. Optical detectors for dual axis tracking
of the sun are known.
[0010] The above-identified proposals and installations have failed
to provide reliable, low cost, efficient, variable capacity systems
by which solar energy is converted to electrical energy. A long
felt need has existed for solar energy conversion plants which are
reliable, efficient, cost effective and size variable to meet both
low and high capacity demands for thermal and electrical
energy.
[0011] Further, the prior art has failed to maximize production of
electricity from a solar generator by not using effluent coolant
(by which the temperature of the solar generator is controlled) as
a secondary source for producing additional electricity. Also, the
prior art fails to meaningfully identify a commercial way by which
a heated coolant, having only a moderately elevated temperature,
can be used to cost effectively produce electricity or do other
work.
[0012] Heretofore, the Rankine cycle principle has been applied to
convert thermal energy into mechanical energy into electricity only
in very expensive complex plants comprising steam driven turbines
typically operating within a temperature range of 850.degree. F. to
1100.degree. F., under high pressure. Fossil fuels are used to
drive boilers which produce the high temperature, high pressure
steam. Fossil fuel conversion efficiencies of these types of
installations may be as high as approximately thirty seven percent
(37%).
BRIEF SUMMARY AND OBJECTS OF THE PRESENT INVENTION
[0013] In brief summary, the present invention overcomes or
substantially alleviates long term problems of the prior art by
which solar energy is cost effectively converted to electrical
energy and thermal energy and the thermal energy is thereafter
converted to electrical energy as well. The present invention also
provides for conversion of low temperature thermal energy, wherever
obtained, to electrical energy using a novel Rankine cycle
mechanism to drive an electrical generator in a cost effective way.
The Rankine cycle mechanism can do other work as well. The present
invention provides reliable, cost effective ways for conversion of
solar energy and thermal energy to electricity, where the size of
the system can be correlated to the desired capacity.
[0014] With the foregoing in mind, it is a primary object of the
present invention to overcome or substantially alleviate long term
problems of the prior art by which solar energy is converted to
thermal energy and electrical energy and the thermal energy is
thereafter converted to electrical energy.
[0015] Another paramount object of the present invention is to
provide reliable, cost effective systems and methods for conversion
of solar energy to electricity and thermal energy and to thereafter
use the thermal energy to create additional electricity or do other
work, where the size of any such system can be correlated to a
desired capacity.
[0016] Still another important object is to provide systems and
methods for the conversion of low temperature thermal energy,
wherever obtained, to electrical energy or do other wok using a
novel Rankine cycle mechanism by which a generator is driven or
another work performing mechanism is driven, in a cost effective
way.
[0017] It is a further valuable object to provide a novel energy
transforming Rankine cycle mechanism and related methodology.
[0018] These and other objects and features of the present
invention will be apparent from the detailed description taken with
reference to accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic of a solar-to-electrical and thermal
energy conversion system within the scope of the present invention,
where the thermal energy is converted to electricity or used to do
other work;
[0020] FIG. 2 is a schematic of a thermal-to-electrical energy
conversion system within the scope of the present invention;
[0021] FIG. 3 is a perspective of a Rankine cycle mechanism, in its
assembled condition, viewed from the mechanical output side, with
the exterior housing removed, constructed in accordance with the
principles of the present invention;
[0022] FIG. 4 is a perspective of the Rankine cycle mechanism of
FIG. 3, in its assembled condition, viewed from the side opposite
to FIG. 3;
[0023] FIG. 5 is an exploded perspective of the Rankine cycle
mechanism of FIG. 3 for clarity of illustration; and
[0024] FIG. 6 is a perspective of the Rankine cycle mechanism of
FIG. 3 with the near side plate removed, for clarity of
illustration.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0025] The present invention is specifically related to solar
generation of electricity in combination with secondary generation
of electricity, or the doing of other work, using heated coolant
from the solar generator in conjunction with a Rankine cycle
mechanism and also to Rankine cycle production of work and/or
generation of electricity using a fluid having a moderately
elevated temperature.
[0026] The present invention utilizes, in some forms, the free and
limitless energy of the sun to produce electricity and thermal
energy. The scale of commercial installations of the present
invention can be tailored to the need, ranging from small stand
alone systems for residential and small business use to
intermediate sized plants for plant or factory use to massive
assemblies design to supplement the supply of electricity or to
mitigate against if not eliminate an electrical energy crisis, such
as the recent one in California. The present invention is
economical to install and maintain, is reliable and not
maintenance-intensive, is efficient and cost effective to operate
and does not pollute the environment. The sun is not a consumable
resource.
[0027] Using the present invention, businesses, industrial plants,
retail and office buildings, homes, farms and villages can produce
some, if not all, of their own electrical power, and avoid one of
the largest if not the largest uncontrollable cost of doing
business today--the ever-escalating price of purchased electrical
power generated from fossil and nuclear fuels.
[0028] This invention is capable of making significantly more
energy per square foot than conventional solar collectors. Prior
art flat plate collectors are incapable of co-generating the large
amounts of thermal energy that the present concentrating
photovoltaic generating systems make, which thermal energy, in
accordance with the present invention can be converted to
electrical energy as well.
[0029] Until now, remote installations have been faced with a
difficult choice, i.e. pay the prohibitive costs of bringing in
utility power, or depend on costly, noisy, and hard to maintain
pollution-creating diesel, gas or propane driven electrical
generators. The present invention is a better choice, which can be
scaled or sized to independently produce as much electrical energy
as needed on site, such as the energy needed to power a home or
business, pump water, irrigate land and run remote communication
installations.
[0030] Unlike centralized forms of power generation, de-centralized
use of on-site solar obtained electrical power needs no far-flung
distribution network of gigantic towers and high voltage lines.
Instead it utilizes a universally available asset--sunshine.
[0031] Decentralized sunlight-derived electrical power can free
users from the effects of peak-hour brown-outs, and from the
possibility of total black-outs caused by operator error, system
breakdowns or planned terrorist's actions of groups hostile to
utilities or nations.
[0032] The cost of the generating equipment itself used in the
production of power for a building can be amortized over the life
of the building, as part of debt financing (mortgage). Amazing as
it may seem, one of the largest and most uncontrollable costs a
building owner faces is the ever-escalating cost of electrical
power. Using the present invention, one actually has the ability to
eliminate most of the cost of purchased electrical power now and
for years to come.
[0033] When land and water were plentiful and labor was cheap,
little was known about the delicate balance existing between the
environment and the extraction, burning, and wasting of
non-renewable fuels. Now it is all too apparent that our supply of
fossil fuels is limited--and that these sources are causing damage
to our atmosphere, water supplies, and food chain--damage that is
or may soon become irreversible. The costs, too, for fossil fuels
continue upward as the more accessible fuel deposits are consumed,
and as the costs for machinery, labor, and transportation continue
to rise around the world.
[0034] Ironically, the best answer to the world's need for energy
has always been the sun. The sun can satisfy a significant
percentage of our energy requirements while helping us to become
independent of the negative aspects inherent in conventional
electrical power generation. Switching to solar-derived electrical
power will reduce the pollution produced by coal, oil and nuclear
fuels. It will also slow the use of coal and oil and allow us to
conserve these resources for more later and perhaps valuable uses.
Harnessing the sun will also reduce, or eliminate, the need for
nuclear power and mitigate its many risks and problems.
[0035] Even though the sun is just beginning to contribute to
satisfying the world's energy demands on a large scale, direct
sunlight has been powering satellites and spacecraft since 1958. In
the 1970's the first terrestrially-directed sunlight photovoltaic
devices supplied power to locations too remote to have ties to
utility lines. Then, as the solar industry developed more efficient
silicon cells and generators, larger grid-connected direct sunlight
installations became practical.
[0036] The present invention is not space-intensive. The present
invention, in some forms, can be mounted on an existing rooftop so
that it essentially takes up no additional space at all.
Ground-mounted systems on a pad or superimposed above a parking lot
are also options as well. Column mounting is a further option.
[0037] Various embodiments of the present invention may be used in
conjunction with residences, office buildings, manufacturing
facilities, apartment buildings, schools, hospitals, remote
communications, telemetry facilities, offshore platforms, water
pumping stations, desalination systems, disinfection systems,
wilderness camping, headquarters installations, remote medical
facilities, refrigeration systems, farms and dairies, remote
villages, weather stations, and air conditioning systems, to name a
few.
[0038] The present invention is also useful in: (a) providing
cathodic protection against galvanite corrosion, (b) storage of
electrical energy in batteries, in some circumstances and (c)
generation and sale of electricity to utility companies.
[0039] The sun is an energy source that, unlike fossil fuels, is
free each day to whatever generation site is selected. It does not
need to be mined, transported, refined, burned or purchased. So the
costs for all these steps to produce energy are eliminated. Gone,
too, are all forms of pollution. There are no particulates or gases
vented into the atmosphere. Nor is there a need for millions of
gallons of cooling water. (The small amount of liquid coolant used
to cool the solar cells actually becomes a second form by which
electrical power may be co-generated. In other words, production of
thermal energy carried away by the coolant may be used to create
additional electrical power.) Preferably, the liquid coolant is
recirculated and reused to conserve the coolant There is no
discharge of massive amounts of hot water into coastal waters to
elevate the normal temperature and alter and perhaps destroy the
habitats and food chains of coastal marine life. With solar energy,
there are no wastes of any kind to be removed or buried in mines or
dumped at sea, so there are few, if any, health risks to our
generation or future generations.
[0040] Various embodiments of the invention are modular, allowing
any installation to be large, medium or small so as to meet the
exact needs of the installation for electrical energy. The
electricity produced by solar cells of a solar electrical generator
is direct current (DC), which, when appropriate, may be transformed
into alternating current (AC) using an inverter or DC-to-AC
converter. The electricity produced from thermal energy using a
Rankine cycle mechanism according to the present invention may be
DC, AC or three phase AC, depending on the type of generator
selected for use with the Rankine cycle mechanism.
[0041] The prior art has failed to maximize production of
electricity from a liquid cooled solar generator in that the
coolant has not been used to co-produce additional electricity, or
as a source by which other types of work can be done. The prior art
fails to meaningfully identify a commercial way by which a heated
liquid having only a moderately elevated temperature can be used to
cost effectively produce electricity or do other work.
[0042] Previously, the Rankine cycle principle has been limited to
conversion of thermal energy into mechanical energy, and thence
into electrical energy, only in expensive, complex plants
comprising steam driven turbines typically operated within the
range of 850.degree. F. to 1100.degree. F., under high pressure.
Fossil fuels often drive boilers which produce the high
temperature, high pressure steam. Fossil fuel conversion
efficiencies of these types of installations can be as high as
approximately thirty seven percent (37%).
[0043] The present invention overcomes or substantially alleviates
the long term problems of the prior art which failed to use solar
energy to cost effectively convert the same to electrical energy
and thermal energy as well, and failed to use the thermal energy to
co-generate electricity. The present invention provides for
conversion of low temperature thermal energy, however obtained, to
electrical energy using a novel Rankine cycle mechanism to drive an
electrical generator in a cost effective way. The mechanical energy
of the Rankine cycle mechanism can do other work as well. The
present invention provides reliable, cost effective ways for
conversion of solar energy and/or thermal energy into electricity,
where the size of the system can be cost effectively correlated to
the desired capacity. The Rankine cycle aspects of the present
invention employ a coolant comprising a low temperature heated
liquid. The Rankine cycle mechanism drives a generator to produce
electricity of the type desired. The low temperature heated liquid
may be passed along a closed loop through a heat exchanger where
heat is transferred from the liquid to a gas which, in turn, is
displaced along another closed loop through the Rankine cycle
mechanism. The heated liquid will have a temperature below its
vapor point, e.g. the temperature of the liquid, when the liquid is
water, will be 210.degree. F. or less. The gas may be within the
range of 50.degree. F.-80.degree. F., typically.
[0044] When the Rankine cycle aspects of the present invention are
used in conjunction with a solar generator, there is an estimated
thirty percent increase in the overall amount of electricity
generated.
[0045] Generation of electricity in accordance with the present
invention, allows for delivery of the energy at desired points in
time, for example, when conventional sources of energy are
inadequate, such as during peak load periods of time, or during
blackouts or in settings where access to conventional electricity
is either difficult or impossible.
[0046] The heated liquid can be stored in one or more insulated
containers or tanks and used later at selected times to produce
electricity using the Rankine cycle aspects of the present
invention.
[0047] The Rankine cycle mechanism, in a presently preferred form,
comprises a twin rotor, positive displacement device operated by
displacement of low temperature fluid heated by liquid coolant used
to cool the solar cells of a solar generator. Other sources of
heated liquid having a temperature below the vapor point may be
used to drive the Rankine cycle mechanism. Preferably, the heated
liquid, when comprising a coolant used with a solar generator, is
recirculated between the solar generator and heat exchanger.
Preferably, the gas, passed through the same heat exchanger, is
recirculated not only through the Rankine cycle mechanism but
through a cooling tower or condenser as well before being returned
to the coolant-gas heat exchanger, which causes the gas to expand
and, therefore, aids in the gas being displaced through the Rankine
cycle mechanism. Thus, both the coolant and the gas are contained
within their respective closed loops, with the system being
predicated upon low temperature, low pressure, pollution free
operational characteristics. The overall efficiency of this system
is projected to be over forty two percent (42%).
[0048] Thus, the present invention concerns itself with using solar
energy to co-generate both primary and secondary electricity
through conversion, at a solar electric generator, of solar energy
to electrical energy and deriving further electricity by using the
thermal energy, of a coolant used to control the temperature of the
solar electrical generator, to drive a Rankine cycle generating
system. In lieu of the secondary electricity, the coolant, at
moderately elevated temperatures, can drive another mechanism which
does other work. The coolant liquid will have a temperature below
its vapor point and gas, heated by the coolant in a heat exchanger,
will have a low temperature which may be within the range of
50.degree. F.-80.degree. F.
[0049] The Rankine cycle system comprises a Rankine cycle mechanism
comprised of shaft-mounted lobes, turned oppositely by successively
applying the force of the heated gas to first one lobe and then to
the other. The shafts upon which the lobes are respectively mounted
are preferably interconnected by toothed wheels or gears so that
rotation of one shaft mechanically causes an opposite rotation of
the other shaft at the same speed and vice versa. The lobes are
constructed so that there is no "blow-by" effect. Shaft rotation
(mechanical energy) is used to do work, including but not limited
to the rotation of a commercially-available electric generator.
[0050] After the heated gas has been used to drive the Rankine
cycle mechanism, in the presently preferred embodiment, the gas is
cooled in a cooling tower or the like, to which the liquid coolant
is not directed.
[0051] The continuous flow of the coolant and the gas takes place
in a closed system comprised respectively of a closed liquid flow
loop and a closed gas flow loop. Thus, nothing is emitted to the
environment or atmosphere which could potentially be harmful.
[0052] The electricity produced from commercial solar generators is
DC, requiring use of a DC-to-AC converter to obtain AC electricity.
The electricity derived from rotation of the Rankine cycle
mechanism can be tailored as desired and may be used to produce any
type electricity desired. The nature of the electricity produced as
a result of rotation of the Rankine cycle mechanism will be
determined by the nature of the generator selected for use.
[0053] A second heat exchanger (the cooling tower) comprises part
of one of the disclosed system through which the gas is
continuously displaced. The gas is also displaced through a first
heat exchanger where heat from the liquid coolant, passed
continuously but separately passed through the first heat exchanger
is transferred to the gas. Displacement of the gas through its loop
is by pump driven circulation, or by temperature differential or
both. Circulation of the liquid coolant is by pump.
[0054] Specific reference is now made to the Figures wherein like
numerals are used to indicate like parts throughout. Specifically,
illustrated in diagrammatic or schematic form in FIG. 1 is one of
several novel systems, generally designated 10, which also
implements unique methodology. More specifically, FIG. 1
illustrates a solar electric generator 12, through which liquid
coolant is circulated to cool solar cells. The liquid coolant is
illustrated as flowing within a closed loop comprising an influent
tube 14, a path through the generator 12 where heat created in a
solar-to-electric process is transferred to the coolant, through an
effluent tube 16, and thence a pump 18, a heat exchanger influent
tube 20, and the interior of an insulated storage tank/expansion
heat exchanger 22, in separation from the fluid in the form of gas
circulated through coils 24 also disposed within the interior of
the tank/heat exchanger 22. If desired the liquid in heat exchanger
22 may be contained in a coil juxtaposed the gas coil 24. The
liquid coolant may be water having an elevated temperature below
boiling. Output from a fuel cell may comprise the liquid introduced
at tube 40.
[0055] The size of the tank/heat exchanger 22 may be a variable,
ranging from extremely large to relatively small, depending upon
design criteria. The smaller the tank/heat exchanger, the lower its
storage capacity for the liquid coolant, the temperature of which
is below the vapor point. The larger the tank the greater the
storage capacity. The closed loop in which the liquid coolant is
circulated accommodates, if desired, continuous circulation of
coolant during the periods when the solar electric generator 12 is
exposed to sunlight. During darkness or heavy overcast, the heated
liquid coolant at the interior 26 of the tank/heat exchanger 22 can
remain static, without circulation with the pump 18 off, as the
expandable gas is displaced through the coils 24, in a manner and
for purposes yet to be more fully described. The flow of the
coolant and the gas is laminar, not turbulent. Heated liquid can
also be stored in insulated tanks other than or in addition to tank
22 for Rankine cycle generation of electricity during darkness or
cloudy days. In this way, storage of generated electricity in
batteries can be eliminated or minimized.
[0056] While any liquid cooled solar electric generator may
comprise generator 12, the solar generators disclosed in the
above-mentioned copending U.S. patent application Ser. No.
09/867,196 may be utilized. The photovoltaic solar cells of these
solar generators produce electricity, in a manner well understood,
which is output from generator 12 along electric cable 28. This
electricity is DC and can be used as such to drive DC devices, if
desired. However, if AC electricity is desired, the DC electricity
in line 28 may be converted at DC-to-AC converter 30 and
transmitted thereafter as AC along cable 32 to either a utility
interconnect 34 and thence along cable 36 to a utility grid or used
on site, as depicted at 38 in FIGS. 1 and 2.
[0057] The heat transfer coils 24 through which the expandable gas
mentioned above passes is part of a closed loop comprising
seriatim, in the direction of flow beginning with the coil 24, a
gas discharge tube 40, a Rankine cycle mechanism 42, a tube 44,
through which gas discharge from the Rankine cycle mechanism 42 is
displaced and from which the gas is introduced into a cooling coil
46 disposed in the interior 47 of a conventional cooling tower
(heat exchanger) 48. Effluent gas from the cooling tower 48 is
displaced along tube 50, through pump 52, if used, and once more
introduced into the heating coil 24 through tube 54.
[0058] The output from the Rankine cycle mechanism 42 is used to
drive a commercially available generator 56. As stated above,
electricity derived from the generator 56 may be used in any
suitable way, such as but not limited to site use, at 38 or sold to
a utility company and communicated through the utility interconnect
34 to a utility grid system along cable 36.
[0059] Reference is now made to FIG. 2, which illustrates a second
system, generally designated 60, in accordance with principles of
the present invention. A number of the components of the system 60
are identical to components of system 10, which are described
above. Therefore, no further description of these components is
needed at this juncture. Accordingly, only the differences found in
FIG. 2, when compared with FIG. 1, will be explained. Independent
of source, heated liquid having a temperature below the vapor
temperature thereof, is introduced along tube 20' into the interior
26 of the tank/heat exchanger 22. The source of the heated liquid
delivered through tube 20' can be any source such as geothermal
water, discharged from any type of temperature lowering system,
etc. The heated influent liquid can be passed through tank/heat
exchanger 22 once or several times as deemed appropriate by those
skilled in the art. The heated liquid delivered through influent
tube 20' may also be stored, as explained above in tank/heat
exchanger 22. The liquid with the interior 26 of tank/heat
exchanger 22, when discharged, is discharged through effluent tube
14'. In situations where tank/heat exchanger 22 has inadequate
heated liquid storage capacity, the quantity of heated liquid being
processed or stored may be enlarged by using one or more insulated
storage tanks 62, the contents of which is returned to the interior
26 of the tank/heat exchanger upon demand, using pump 64. In any
event, heated liquid contained within the interior 26 of tank/heat
exchanger 22, either in static position or being circulated
therethrough, transfers heat to the previously mentioned gas
passing through coils 24. Displacement of the heated gas drives the
Rankine cycle mechanism 42, as explained above, such that
electricity can be obtained when the Rankine cycle mechanism 42
turns generator 56, which electricity can be communicated through
cable 57 for on-site or nearby use or through cable 59 to utility
interconnect 34. In addition or in concert with driving generator
56, the Rankine cycle mechanism 42 illustrated in FIG. 2 may be
used to turn another device by which other work is done, as
depicted at site 66.
[0060] Reference is now made to FIGS. 3 through 6, which illustrate
one appropriate form of the Rankine cycle mechanism 42, fashioned
in accordance with the principles of the present invention. In some
embodiments, the mechanism 42 provides the advantage of
portability. While the capacity and size of the mechanism 42 may
vary, RPM within the range of 200-5000 producing 5 horsepower can
be produced. FIGS. 3 through 6 depict the illustrated Rankine cycle
mechanism 42, with exterior side housings removed. The side
housings are essentially opposite clamshells with aperture
peripheral flanges, which, when assembled, prevent entry of debris
and protect against injury. The side housings are respectively
secured at the respective apertured flanges by screws which
threadedly pass through the apertures of the flanges and aligned
sequential threaded apertures 70 in the other components of the
mechanism.
[0061] Exclusive of the housing, the Rankine cycle mechanism shown
in FIGS. 3 through 6 comprises three successive contiguous plates
72, 74 and 76. Plates 72, 74 and 76 are relatively thin and planar,
sized to create a close tolerance fit between the central plate 74
and the two exterior side plates 72 and 76 to thereby prevent fluid
leakage at interfaces 78 and 80. Accordingly, plates 72 and 76 have
interior and exterior smooth flat interior and exterior surfaces
and are preferably formed of a suitable metal, which is not subject
to corrosion and does not significantly expand due to the elevated
temperature of the fluid passing through the mechanism 42 via
influent tube 40 and effluent tube 42. A pressure at influent tube
40 of 15 psi under some circumstances may be suitable. Suitable
metals for fabrication of plates 72 and 76 comprise aluminum,
steel, and brass. One or both plates 72 and 76 may, in the
alternative, be formed of a suitable dimensionally stable rigid
synthetic resinous material, such as ABS or
polytetrafluoroethylene, or composite materials may be used.
[0062] While other materials could be used to form layer 74,
presently a wear resistant, dimensionally stable rigid and durable
synthetic resinous material such as ABS, or polytetrafluoroethylene
is preferred. Composite materials may also be used to form layer
74. Layer 74, unlike layers 72 and 76, is peripheral only,
comprising a central, figure 8-shaped hollow interior 84,
accommodating receipt and the close tolerance rotation of two
adjacent, interfunctional lobes 86 and 88, as explained later in
greater detail. See FIGS. 5 and 6. Lobes 86 and 88 may be formed of
rigid dimensionally stable synthetic resinous material, metal or
composites. The central layer 74 also comprises an interior
influent discharge port 120, in open fluid communication with
influent tube 40 by which the fluid in tube 40 is introduced
successively into four lobe cavities, as explained herein in
greater detail. The central layer 74 also comprises an effluent
port 122 in open communication with discharge tube 42, for the
purpose explained above. The male projections of the two lobes 86
and 88 comprise surfaces 110 and cavities 112, defined by surfaces
114 and 116. The lobes 86 and 88 are sized so that at times during
opposite rotation, the projections each comprising surfaces 110
turn into and through the female cavities 112. See FIG. 6.
[0063] The oppositely rotating, intermeshing lobes 86 and 88 are
non-rotatably connected, respectively, to the two parallel shafts
43, in any conventional way, such as by use of a press-fit race 89,
or a key/keyway or set screw interconnection. The illustrated race
89 projects beyond the associated lobe 86 or 88. The shafts are
rotatably journaled in apertures 94 of the outside plates 72 and
76, respectively, using bushings 90 and 92, one at each end of each
shaft fitted for rotation into apertures 94 (FIG. 5) in each of the
two side plates 72 and 76. The bushings 90 and 92 are slotted at 95
so that the radially size can be adjusted, by loosening or
tightening an associated set screw 91 which threadedly crosses the
slot to thereby size the bushing for close tolerance rotation in
the apertures 94 while being non-rotatably connected to the
associated shaft 43. The two shafts 43, respectively, terminate at
their proximal ends a very short distance outside the plate 72.
These proximal shaft ends are concealed by a pair of caps 96 (FIG.
4) screw fastened at 98 to the plate 72. Caps 96 may be formed any
suitable material, such as acceptable synthetic resinous
material.
[0064] To the contrary, the distal ends of each shaft 43 projects
well beyond the exterior surface of plate 76, as best shown in FIG.
3. Thus, the distal ends of the shafts are output shafts, the
rotation or torque of which is converted to mechanical energy from
which desired work is obtained, such as the generation of
electricity.
[0065] A pair of interconnected toothed wheels or gears 100 are
non-rotatably connected, respectively, to the two shafts 43 using
any suitable technology. Set screws in threaded apertures 101 are
illustrated in FIG. 3 as being used. Accordingly, when the lobes
oppositely rotate, the two shafts 43 oppositely rotate and the two
gears, interconnected at site 102, also oppositely rotate and at
the same speed. As explained hereinafter in greater detail, the
positive displacement, driving force of the influent fluid entering
at port 40 drives one of the lobes at a first point in time, with
the other lobe following by reason of the gear interconnection at
site 102. Thereafter, the influent fluid drives the second lobe,
with the first lobe becoming a follower, again by reason of the
interconnection of gear teeth 104 at site 102.
[0066] The mechanical energy or torque, which occurs when shafts 43
rotate, is converted to electrical energy at generator 56 (FIGS. 1
and 2) or used to do other work at 66 (FIG. 2).
[0067] As can best be seen in FIG. 6, the lobes 86 and 88 are
identical in the embodiment illustrated and described. Three
hundred sixty degree (360.degree.) rotation of each lobe will
entail two driver intervals for each lobe and two idler or follower
intervals for each lobe.
[0068] To prevent blow-by, each lobe comprises opposite maximum
diameter male radial wall surfaces or edges 110, which rotate in
close tolerance relationship with the FIG. 8 shaped surface 84 of
the central peripheral layer 74, as best shown in FIG. 6. Because
of the close tolerance relationship between surfaces 110 and
surface 84, there is no material "blow-by" loss of pressure or
fluid flow during rotation.
[0069] Further, each lobe 86 and 88 comprise opposed kidney-shaped
slots or grooves 112. Slots 112 comprise a central reduced diameter
radial surface 114 and forward and rear rounded surfaces 116 each
of which merges with the associated outer radial surface 110 and
the associated surface 114. The driving force of the influent fluid
entering at influent tube 40 and interior port 120 is predominantly
applied to the leading surface 116 within one groove 112 of the
lobe 86 or 88 being driven by the fluid pressure at that point in
time. The trailing surface 116 of the one groove 112 will cause
discontinuance of influent fluid pressure against the associated
leading surface 116 of the same kidney-shaped groove 112, once the
trailing surface 116 passes the interior discharge port 120 and
temporarily closes that groove 112 to fluid access from port 120.
At this point in time, the leading surface 116 of one of the
grooves 112 of the other lobe will be placed in communication with
the influent fluid under pressure entering the Rankine cycle
mechanism at interior port 120, so that the second lobe becomes the
driver and the first lobe becomes the follower, as explained above.
This alternation in driven lobe/follower lobe sequence occurs twice
per lobe for each 360.degree. rotation of the two lobes 86 and 88.
Spent driving fluid is discharged through interior port 122 and out
through effluent tube 44. See FIG. 6.
[0070] The fluid used to drive the lobes 86 and 88 may be of any
suitable composition. A plurality of mechanisms 42 can be used in
series, in parallel or both. Gas, including steam, is preferred,
but under certain circumstance liquid may be used.
[0071] The invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The present embodiments are therefore to be considered in
all respects as illustrative and not restrictive, the scope of the
invention being indicated by the appended claims rather than by the
foregoing description, and all changes which come within the
meaning and range of equivalency of the claims are therefore
intended to be embraced therein.
* * * * *