U.S. patent application number 13/389023 was filed with the patent office on 2012-10-04 for solar collector with expandable fluid mass management system.
This patent application is currently assigned to ECHOGEN POWER SYSTEMS, LLC. Invention is credited to Michael Gurin, Timothy James Held, Jason D. Miller.
Application Number | 20120247455 13/389023 |
Document ID | / |
Family ID | 43544680 |
Filed Date | 2012-10-04 |
United States Patent
Application |
20120247455 |
Kind Code |
A1 |
Gurin; Michael ; et
al. |
October 4, 2012 |
SOLAR COLLECTOR WITH EXPANDABLE FLUID MASS MANAGEMENT SYSTEM
Abstract
Solar energy conversion systems and methods use solar collectors
and working fluid management systems to provide both efficient and
safe operation under a wide range of operating conditions. In one
embodiment, a solar collector and at least one fluid accumulator
preferably with an integral heat exchanger, and at least two mass
flow regulator valves enable working fluid flow into and out of the
fluid accumulator.
Inventors: |
Gurin; Michael; (Glenview,
IL) ; Held; Timothy James; (Akron, OH) ;
Miller; Jason D.; (Hudson, OH) |
Assignee: |
ECHOGEN POWER SYSTEMS, LLC
Akron
OH
|
Family ID: |
43544680 |
Appl. No.: |
13/389023 |
Filed: |
August 6, 2010 |
PCT Filed: |
August 6, 2010 |
PCT NO: |
PCT/US10/44681 |
371 Date: |
June 18, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61231674 |
Aug 6, 2009 |
|
|
|
Current U.S.
Class: |
126/638 ;
126/640; 126/641; 126/645; 126/646; 126/678 |
Current CPC
Class: |
Y02B 10/20 20130101;
Y02B 10/70 20130101; F24D 11/0221 20130101 |
Class at
Publication: |
126/638 ;
126/640; 126/646; 126/641; 126/645; 126/678 |
International
Class: |
F24J 2/04 20060101
F24J002/04; F24J 2/44 20060101 F24J002/44; F24J 2/46 20060101
F24J002/46; F24J 2/30 20060101 F24J002/30 |
Claims
1. A solar energy conversion system comprising: a working fluid
circuit for receiving and directing flow a working fluid within the
working fluid circuit; at least one solar collector in the working
fluid circuit; at least one fluid accumulator in the working fluid
circuit; a pump for moving working fluid in the working fluid
circuit to the solar collector and to the fluid accumulator; the
working fluid circuit also extending between the solar collector
and the fluid accumulator, and from the fluid accumulator to the
pump.
2. The solar energy conversion system of claim 1 further comprising
a cold inlet valve in the working fluid circuit between an output
of the pump and the fluid accumulator.
3. The solar energy conversion system of claim 1 further comprising
a discharge valve in the working fluid circuit between the fluid
accumulator and an intake of the pump.
4. The solar energy conversion system of claim 1 further comprising
an inlet valve to the fluid accumulator in the working fluid
circuit located between the solar collector and the fluid
accumulator.
5. The solar energy conversion system of claim 1 further comprising
a heat source in thermal communication with the fluid
accumulator.
6. The solar energy conversion system of claim 5 wherein the heat
source is a heat exchanger located at least partially within the
fluid accumulator.
7. The solar energy conversion system of claim 5 further comprising
a condenser in thermal communication with the heat source.
8. The solar energy conversion system of claim 1 further comprising
a heat exchanger within the solar collector.
9. The solar energy conversion system of claim 1 further comprising
at least one expansion device in the working fluid circuit.
10. The solar energy conversion system of claim 1 further
comprising a control system operative to control operation of the
pump, and to control: the flow of working fluid from the solar
collector to the fluid accumulator, the flow of working fluid from
the pump to the fluid accumulator, and the flow or working fluid
from the fluid accumulator to the pump by reference to operating
pressures and working fluid temperatures.
11. A method of converting solar energy acquired from a solar
collector and transferred to a working fluid in a working fluid
circuit of a solar energy conversion system having at least one
solar collector in the working fluid circuit, at least one fluid
accumulator in the working fluid circuit, a pump for moving working
fluid in the working fluid circuit to the solar collector and to
the fluid accumulator, the working fluid circuit also extending
between the solar collector and the fluid accumulator, and from the
fluid accumulator to the pump, the method comprising the steps of:
controlling the pump to move working fluid through the working
fluid circuit to the solar collector and to the fluid accumulator;
thermally controlling the fluid accumulator to cool the working
fluid in the fluid accumulator; removing working fluid from the
fluid accumulator by controlling a valve between the solar
collector and the fluid accumulator to an open position when the
working fluid has reached a target set point temperature, and
controlling a discharge valve between the fluid accumulator and the
pump to an open position.
12. The method of claim 11 further comprising the step of removing
working fluid from the fluid accumulator by reference to operating
pressure and temperature of the working fluid in the fluid
accumulator.
13. The method of claim 11 further comprising the step of
monitoring the energy consumption by the pump by use of a mass flow
meter, kilowatt-hour meter, or pump performance map.
14. The method of claim 11 further comprising the step of
calculating an amount of working fluid in the fluid accumulator by
reference to a database of NIST thermophysical properties.
15. A solar energy conversion system comprising: a working fluid
circuit for receiving and directing flow of a working fluid within
the working fluid circuit; at least one working fluid solar
collector in the working fluid circuit; at least one fluid
accumulator in the working fluid circuit and located above the
solar collector, an inlet an inlet valve in the working fluid
circuit connected to an intake of the fluid accumulator, and a
discharge valve in the working fluid circuit between the fluid
accumulator and the solar collector, and a heat source for
controlling a temperature of the fluid accumulator.
16. The solar energy conversion system of claim 15 wherein the heat
source for controlling a temperature of the fluid accumulator is a
heat exchanger in thermal communication with the fluid accumulator
and with a fluid accumulator condenser.
17. The solar energy conversion system of claim 15 further
comprising a heat transfer fluid circuit connected to the
condenser, the heat transfer fluid circuit comprising a heat
transfer fluid condenser and a heat transfer fluid solar collector,
the heat transfer fluid condenser located below the fluid
accumulator condenser and above the heat transfer fluid solar
collector.
18. The solar energy conversion system of claim 15 further
comprising an intake valve in the heat transfer fluid circuit
proximate to an intake to the fluid accumulator condenser.
19. A method of converting solar energy acquired from a solar
collector and transferred to a working fluid in a working fluid
circuit of a solar energy conversion system having at least one
working fluid solar collector in the working fluid circuit, at
least one working fluid accumulator in the working fluid circuit
and means for controlling a temperature of the fluid accumulator,
and wherein the solar collector is located below the fluid
accumulator whereby the working fluid solar collector operates as a
thermosiphon, the method comprising the steps of: controlling
introduction of the working fluid into the fluid accumulator by
operation of an inlet valve in an inlet in the working fluid
circuit to the fluid accumulator; cooling the working fluid in the
fluid accumulator; discharging working fluid from the fluid
accumulator to the working fluid solar collector according to a
desired mass flow rate of the working fluid in the working fluid
circuit.
20. The method of claim 19 wherein the working fluid in the fluid
accumulator is cooled by a heat exchanger in thermal communication
with a fluid accumulator condenser, by controlling flow of a heat
transfer fluid through the fluid accumulator condenser.
21. The method of claim 20 further comprising the step of heating
the heat transfer fluid by a heat transfer fluid solar collector in
a heat transfer fluid circuit connected to the fluid accumulator
condenser.
22. The method of claim 21 further comprising the step of passing
the heat transfer fluid through a condenser in the heat transfer
fluid circuit prior to the heat transfer fluid solar collector.
23. The method of claim 22 further comprising the step of operating
the heat transfer fluid solar collector as a thermosiphon.
24. The method of claim 19 further comprising the step operating
the working fluid solar collector in a substantially stagnant
mode.
25. The method of claim 19 further comprising the step of isolating
a flow of a portion of the working fluid through the fluid
accumulator and the working fluid solar collector from a remainder
of the working fluid circuit.
26. The method of claim 19 further comprising the step of operating
the working fluid solar collector at a temperature relatively
higher than an ambient temperature.
27. The method of claim 19 further comprising the step of operating
the working fluid solar collector at a pressure which is relatively
lower than a pressure in the working fluid circuit.
Description
FIELD OF THE INVENTION
[0001] The present invention is in the general field of
thermodynamics and solar energy conversion.
BACKGROUND OF THE INVENTION
[0002] Due to a variety of factors including, but not limited to,
global warming issues, fossil fuel availability and environmental
impacts, crude oil price and availability issues, alternative
energy sources are becoming more popular today. One such source of
alternative and/or renewable energy is solar energy. One such way
to collect solar energy is to use a solar receiver to focus and
convert solar energy into a desired form (e.g., thermal energy or
electrical energy). Thermal energy harvested from the sun is known
in the art to be utilized in absorption heat pumps, domestic hot
water and industrial processes, power generating cycles through the
heating of a secondary heat transfer fluid, power generating cycles
through the direct heating of power generating working fluid such
as steam, and for heating. Furthermore, it is recognized that a
wide range of energy consumers can be supplied via electrical
and/or thermal energy such as air conditioning, refrigeration,
heating, industrial processes, and domestic hot water. Given this,
solar collectors that function in efficient manners are
desirable.
[0003] Traditional solar systems utilize a non-expandable working
fluid under pressures less than 50 psia, or working fluids having
expandability ratios between the cold and hot temperatures of less
than 3. The traditional solar systems utilize a working fluid that
is a heat transfer fluid and thus isn't directly compatible as a
thermodynamic cycle working fluid. As noted, the density of the
working fluid by being expandable changes by an order of magnitude
as a function of operating pressure and temperature. Furthermore by
definition solar energy is a function of solar intensity and thus
at the minimum is absent during the nighttime, unless significant
thermal storage is utilized that is currently very expensive, the
system will experience substantial changes in density according to
operating and ambient conditions.
[0004] The combined limitations of each individual component being
the solar collector and heat exchangers, pump, heat pump, and fluid
control valves presents significant challenges that are further
exasperated when seeking to operate the solar collector in a
dynamic manner as function of ambient conditions and solar
flux.
SUMMARY OF THE INVENTION
[0005] The present disclosure and related inventions pertain to
solar collectors having an expandable working fluid and an
integrated mass management system. The disclosed embodiments
utilize gravity to discharge a cooler and more dense fluid as
displaced by a volumetrically equivalent warmer and less dense
fluid.
[0006] In accordance with one aspect of the disclosure and related
inventions, there is provided a solar energy conversion system
which has a working fluid circuit for receiving and hold a working
fluid capable of expansion within the working fluid circuit; at
least one solar collector in the working fluid circuit; at least
one fluid accumulator in the working fluid circuit; a pump for
moving working fluid in the working fluid circuit to the solar
collector and to the fluid accumulator; the working fluid circuit
also extending between the solar collector and the fluid
accumulator, and from the fluid accumulator to the pump.
[0007] In accordance with another aspect of the disclosure and
related inventions, there is provided a method of converting solar
energy acquired from a solar collector and transferred to a working
fluid in a working fluid circuit of a solar energy conversion
system having at least one solar collector in the working fluid
circuit, at least one fluid accumulator in the working fluid
circuit, a pump for moving working fluid in the working fluid
circuit to the solar collector and to the fluid accumulator, the
working fluid circuit also extending between the solar collector
and the fluid accumulator, and from the fluid accumulator to the
pump, the method including the steps of: controlling the pump to
move working fluid through the working fluid circuit to the solar
collector and to the fluid accumulator; thermally controlling the
fluid accumulator to cool the working fluid in the fluid
accumulator; removing working fluid from the fluid accumulator by
controlling a valve between the solar collector and the fluid
accumulator to an open position when the working fluid has reached
a target set point temperature, and controlling a discharge valve
between the fluid accumulator and the pump to an open position.
[0008] These and other aspects and concepts of the disclosure and
related inventions are further described herein in detail with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a sequential flow diagram of one embodiment of an
integrated solar collector and inventory mass management system
operating with a mechanically driven pressure generating device in
accordance with the present invention;
[0010] FIG. 2 is a sequential flow diagram of one embodiment of an
integrated solar collector and inventory mass management system
operating in a hybrid thermosyphon approach in accordance with the
present invention;
DETAILED DESCRIPTION OF THE INVENTION
[0011] As used herein, the following terms have the respective
meanings. The term "in thermal continuity" or "thermal
communication", as used herein, includes the direct connection
between the heat source and the heat sink whether or not a thermal
interface material is used. The term "fluid inlet" or "fluid inlet
header", as used herein, includes the portion of a heat exchanger
where the fluid flows into the heat exchanger. The term "fluid
discharge", as used herein, includes the portion of a heat
exchanger where the fluid exits the heat exchanger.
[0012] The present invention generally relates to a solar collect
system having an integral working fluid management system that
enables the system to increase or decrease the mass of the working
fluid within the circulation loop of the closed loop system.
[0013] Here, as well as elsewhere in the specification and claims,
individual numerical values and/or individual range limits can be
combined to form non-disclosed ranges.
[0014] The heat transfer fluid within the embodiments is preferably
a supercritical fluid as a means to reduce the pressure drop within
the heat exchanger. The supercritical fluid includes fluids
selected from the group of organic refrigerants (R134, R245,
pentane, butane), gases (CO2, H2O, He2). A preferred supercritical
fluid is void of hydrogen as a means to virtually eliminate
hydrogen reduction or hydrogen embrittlement on the heat exchanger
coatings or substrate respectively. A preferred supercritical fluid
has a disassociation rate less than 0.5% at the operating
temperature in which the heat exchanger operates. The specifically
preferred heat transfer fluid is the working fluid wherein the
combined energy produced (i.e., both thermal, and electrical)
displaces the maximum amount of dollar value associated with the
displaced energy produced within all of the integrated components
including thermodynamic cycle operable within a power generating
cycle, vapor compression cycle, heat pump cycle, absorption heat
pump cycle, or thermochemical heat pump cycle.
[0015] All of the embodiments can be further comprised of a control
system operable to regulate the mass flow rate of the working fluid
into the solar collector, with the ability to regulate the mass
flow rate independently for each pass by incorporating a fluid tank
having variable fluid levels optionally interspersed between at
least one pass and the other. One method of control includes a
working fluid inventory management system. The control system
regulates the mass flow rate through methods known in the art
including variable speed pump, variable volume valve, bypass
valves, and fluid accumulators. The control system is further
comprised of at least one temperature sensor for fluid discharge
temperature and at least one temperature sensor for ambient air
temperature or condenser discharge temperature.
[0016] Exemplary embodiments of the present invention will now be
discussed with reference to the attached Figures which
schematically illustrate the methods and processes disclosed
herein, as may be embodied in a device or system for conversion of
solar energy into another form of energy or work by use of a
working fluid contained in a working fluid circuit made up of
conduit for containment and transfer or passage or flow of a
working fluid through the conduit and into or through components
which are operatively and fluidly connected to the conduit of the
working fluid circuit. There may be additional components to the
system and the working fluid circuit, such as one or expansion
devices, valves, pumps, heat exchangers, recuperators, condensers
or other components which are not depicted in the Figures. Such
embodiments are merely exemplary in nature. The depiction of solar
collectors predominantly as flat panel non-tracking solar absorbers
with integral microchannel heat exchangers is merely exemplary in
nature and can be substituted by tracking collectors of 1 axis or 2
axis type, vacuum evacuated tubes or panels, switchable
configuration between solar absorber or solar radiator mode, low
concentration fixed collector, or high concentration tracking
collectors. The depiction of pump as a vapor compressor device is
merely exemplary and can be substituted with a positive
displacement device, a gerotor, a ramjet, a screw, and a scroll.
Furthermore, and importantly, the pump can be a turbopump, a
positive displacement pump where the selection of the device to
increase the working fluid pressure and operate as a mass flow
regulator is determined by the density at the inlet pressure and
discharge outlet when the incoming working fluid has a density
greater than 50 kg per m3, or preferably greater than 100 kg per
m3, or specifically greater greater than 300 kg per m3. The
depiction of valves as standard mass flow regulators is merely
exemplary in nature and can be substituted by variable flow
devices, expansion valve, turboexpander, two way or three way
valves. The depiction of methods to remove heat from the working
fluid as a condenser is merely exemplary in nature as a thermal
sink and can be substituted by any device having a temperature
lower than the working fluid temperature including absorption heat
pump desorber/generator, liquid desiccant dehumidifier, process
boilers, process superheater, and domestic hot water. With regard
to FIGS. 1 through 2, like reference numerals refer to like
parts.
[0017] FIG. 1 is a sequential flow diagram of one exemplary
embodiment of a solar collector with integral mass management
system in accordance with the present invention. In the embodiment
of FIG. 1 beginning with the working fluid being discharged from
the pump 70, the working fluid can flow either to the solar
collector 30 or by way of opening the cold inlet valve 40 a partial
stream can enter the expandable fluid accumulator 20. The portion
of the working fluid having entered the fluid accumulator 20 is
cooled either by ambient exposure of the fluid accumulator exterior
at the natural rate realized or accelerated by integrating a heat
exchanger 80 directly immersed in the fluid accumulator 20. The
heat transfer fluid flowing through the heat exchanger 80 is
subsequently cooled by the condenser 50. The working fluid within
the fluid accumulator 20 is now at a cooler temperature than when
it entered thus for an equivalent pressure the working fluid is
more dense. There are disclosed herein two methods to remove
working fluid from the fluid accumulator 20 with the first being
the use of the solar collector to heat a portion of the working
fluid remaining in the main closed loop system by absorbing solar
flux and transferring this thermal energy via an embedded heat
exchanger within the solar collector 30, and the second being the
use of the condenser 50 as a heat source (as compared to the
traditional role as a heat sink). Utilizing the first method, the
pump 70 prevents backflow during normal operation, and the control
system activates the hot inlet valve 10 to the open position when
the solar collector 30 has heated the working fluid to a target set
point temperature (i.e., achieved a specified density by way of the
operating pressure and working fluid temperature). The discharge
valve 60 is subsequently opened by the control system to enable the
relatively low density and higher temperature working fluid to
displace the relatively more dense and lower temperature working
fluid. The method of control includes the ability to monitor pump
70 energy consumption by methods known in the art including mass
flow meter, kilowatt-hour meter, pump performance maps with a known
inlet and discharge pressure, working fluid inlet temperature, and
working fluid discharge temperature. The control system can also
utilize a database of NIST thermophysical properties to precisely
calculate the amount of working fluid within the fluid accumulator
20, or within the closed loop system.
[0018] The second method of discharge centers around the condenser
50 operating in reverse mode, thus as a thermal source instead of a
thermal sink. Under the second method, the control system will
begin the process of using a relatively higher temperature heat
transfer fluid into the embedded heat exchanger of the fluid
accumulator 20 at which point of reaching either or both the target
set point temperature and/or target set point pressure the cold
inlet valve 40 is opened (this assumes that the resulting pressure
within the fluid accumulator is at least temporarily higher than
the closed loop system pressure).
[0019] FIG. 2 is a sequential flow diagram of one embodiment of a
solar energy conversion system and method which includes one or
more solar collectors and one or more fluid accumulators. In the
embodiment of FIG. 2, the fluid accumulator 20 discharges directly
into the solar collector 30 preferably operating as a thermosiphon,
through a discharge valve 60. Beginning with the working fluid at
state point A, at least a portion of the working fluid passes
through the hot inlet valve 10 when the fluid accumulator is
removing working fluid from the main closed loop of the solar
collector thermosiphon system, i.e., the working fluid circuit of
the solar energy conversion system. As with any thermosiphon
system, it is critical that the fluid accumulator 20 be located
above the solar collector 30. The expandable working fluid having
entered the fluid accumulator 20 is cooled through the heat
exchanger 80, which is preferably contained at least partially
within the fluid accumulator 20. The heat transfer fluid utilized
to cool the working fluid is passed through the accumulator
condenser 50.1. The then subsequently cooled working fluid within
the fluid accumulator 20 is discharged through the discharge valve
60 back into the solar collector 30, when desired and controlled by
a control system to regulate the combination of mass flow rate of
the working fluid and the operating pressure of the working fluid
within the safe margins of operation. It is understood that
temperature sensors can be placed at each state point, including
within the fluid accumulator to enable the control system to
regulate the flow of working fluid, and heat transfer fluid to
remove thermal energy from the working fluid as a means of heating
up a thermal sink including domestic hot water, industrial
processes, heating, and even power generation.
[0020] The right side of FIG. 2 schematically depicts the
utilization of a heat transfer fluid that ultimately is heated by a
second solar collector 30.1 (which is effectively may be the same
as solar collector 30 but showing the relative height of each
component to each other) whereby the working fluid removed from the
main closed loop transfers a portion of its thermal energy into to
increase the density of the stored fluid is conserved by subsequent
transfer of the thermal energy to increase from state point T1 as
it passes through valve 90 and the fluid accumulator condenser
50.1, now becoming state point D having a temperature sensor T2
100. This stage effectively operates as a preheat of the heat
transfer fluid, then passes through the condenser 50 of the main
loop now becoming state point E having a temperature sensor T3 110
to continue the flow through the solar collector 30 (or as depicted
30.1). The operation of the solar collector as a thermosiphon
requires T1<T2<T3.
[0021] It is anticipated that the removal of working fluid from the
closed loop system into the fluid accumulator 20 can result from
the solar collector operating in essentially a stagnation mode
(thus being a safety precaution to limit the solar collector from
exceeding it's maximum operating pressure specifications), the
closing and/or evacuation of a parallel circuit within the closed
loop system, capturing at least a portion of the working fluid
"charge" within the closed loop system prior to maintenance of the
entire system, enabling the solar collector to operate at
relatively higher ambient temperatures, and/or enabling the solar
collector to operate at relatively lower operating pressure. The
counterpart is the addition of working fluid into the closed loop
system from the fluid accumulator 20 as a result of relatively
lower ambient temperatures, the opening and/or filling of a
parallel circuit within the closed loop system, enabling the solar
collector to operate at relatively lower ambient temperatures,
and/or enabling the solar collector to operate at relatively higher
operating pressure.
[0022] It is understood in this invention that a combination of
scenarios can be assembled through the use of fluid valves and/or
switches such that any of the alternate configurations can be in
parallel enabling the solar collector to support a wide range of
thermal sinks.
[0023] Although the invention has been described in detail with
particular reference to certain embodiments detailed herein, other
embodiments can achieve the same results.
[0024] Variations and modifications of the present invention will
be obvious to those skilled in the art and the present invention is
intended to cover in the appended claims all such modifications and
equivalents.
* * * * *