U.S. patent application number 15/567732 was filed with the patent office on 2018-05-03 for device for collecting solar energy by means of a concentrator of the nonimaging type.
This patent application is currently assigned to KING ABDULAZIZ CITY FOR SCIENCE & TECHNOLOGY. The applicant listed for this patent is EZ-ENERGIES GMBH, KING ABDULAZIZ CITY FOR SCIENCE & TECHNOLOGY. Invention is credited to Yousef M. AL-YOUSEF, Andrea DE RICCARDIS, Tobias KOCH.
Application Number | 20180119993 15/567732 |
Document ID | / |
Family ID | 53836680 |
Filed Date | 2018-05-03 |
United States Patent
Application |
20180119993 |
Kind Code |
A1 |
DE RICCARDIS; Andrea ; et
al. |
May 3, 2018 |
DEVICE FOR COLLECTING SOLAR ENERGY BY MEANS OF A CONCENTRATOR OF
THE NONIMAGING TYPE
Abstract
The present invention concerns a device for collecting solar
energy by means of a concentrator of the nonimaging type and a
receiver for the transfer of energy by heat exchange with a fluid
which operates, independently, a thermodynamic cycle for the
exploitation of energy, said concentrator comprising an inlet area,
an underlying outlet area and an inner space between said inlet
area and said outlet area; said receiver being positioned under
said concentrator and said inner space of the concentrator and said
receiver being connected by said outlet area, characterized in that
said inner space of the concentrator and said receiver are in fluid
communication through said outlet area, a plurality of solid
particles are present inside said receiver, and said device for
collecting solar energy comprises means apt to take a part of said
solid particles from said receiver and to put them from below
inside said inner space of said concentrator, said solid particles
subsequently returning, by gravity, into said receiver, passing
through said outlet area.
Inventors: |
DE RICCARDIS; Andrea;
(Lecce, IT) ; KOCH; Tobias; (Zug, CH) ;
AL-YOUSEF; Yousef M.; (Riyadh, SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KING ABDULAZIZ CITY FOR SCIENCE & TECHNOLOGY
EZ-ENERGIES GMBH |
Riyadh
Augsburg |
|
SA
DE |
|
|
Assignee: |
KING ABDULAZIZ CITY FOR SCIENCE
& TECHNOLOGY
Riyadh
SA
EZ-ENERGIES GMBH
Augsburg
DE
|
Family ID: |
53836680 |
Appl. No.: |
15/567732 |
Filed: |
April 21, 2016 |
PCT Filed: |
April 21, 2016 |
PCT NO: |
PCT/IB2016/052255 |
371 Date: |
October 19, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F24S 70/10 20180501;
F24S 20/20 20180501; Y02E 10/41 20130101; F24S 2023/83 20180501;
F24S 23/79 20180501; Y02E 10/40 20130101; F28D 13/00 20130101; F24S
23/70 20180501; F24S 80/20 20180501 |
International
Class: |
F28D 13/00 20060101
F28D013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 21, 2015 |
IT |
102015000012520 |
Claims
1. Device for collecting solar energy by means of a concentrator of
the nonimaging type and a receiver for the transfer of energy by
heat exchange with a fluid which operates, independently, a
thermodynamic cycle for the exploitation of energy, said
concentrator comprising an inlet area, an underlying outlet area
and an inner space between said inlet area and said outlet area;
said receiver being positioned under said concentrator and said
inner space of the concentrator and said receiver being connected
by said outlet area, wherein said inner space of the concentrator
and said receiver are in fluid communication through said outlet
area, a plurality of solid particles are present inside said
receiver, and said device for collecting solar energy comprises
means apt to take a part of said solid particles from said receiver
and to put them from below inside said inner space of said
concentrator, said solid particles subsequently returning, by
gravity, into said receiver, passing through said outlet area.
2. Device for collecting solar energy according to claim 1, wherein
said means apt to take said solid particles from said receiver and
to put them from below inside said inner space of said concentrator
comprise an input device.
3. Device for collecting solar energy according to claim 1, wherein
said means apt to take said solid particles from said receiver and
to put them from below inside said inner space of said concentrator
are made of streams of gases, vapours, or by a combination of the
same, apt to raise said solid particles up to a height comprised
between said inlet area and said outlet area of the
concentrator.
4. Device for collecting solar energy according to claim 2, wherein
said receiver and said means apt to take said solid particles from
said receiver and put them inside said inner space of said
concentrator are made of a spouted bed.
5. Device for collecting solar energy according to claim 1, wherein
said concentrator is a CPC concentrator (Compound Parabolic
Concentrator).
6. Device for collecting solar energy according to claim 1, wherein
said solid particles are made of a material with high solar
absorption and low emissivity.
7. Device for collecting solar energy according to claim 1, wherein
said solid particles are made of oxides of the metallic type.
8. Device for collecting solar energy according to claim 7, wherein
said solid particles are made of chromite
((Mg,Fe)(Cr,Al).sub.2O.sub.4).
Description
[0001] The present invention concerns a device for collecting solar
energy by means of a concentrator of the nonimaging type.
[0002] The invention is referred to the field of devices for
collecting solar energy of the nonimaging type (NIO), such as CPC
(Coumpond Parabolic Concentrator), and in particular to a new way
of operating and using the same.
[0003] It is known that the solar radiation reaching the surface of
the Earth has mean values of thermal flux around 1 kWh/m.sup.2:
such a value is too low and economically non convenient to be
exploited in pants of production of electric energy.
[0004] As a consequence, starting from the need to concentrate high
density fluxes over small surfaces, developed the first studies on
the concentration optical systems and, in particular, those
dedicated to nonimaging optics (NIO). In fact, such concentration
devices have the advantage of optimizing the transmission of energy
from a source to a receiver, instead of forming the typical image
of the optic systems (IO) and with no relevance in the field of
energy transfer.
[0005] The CPC (Compound Parabolic Concentrator), evolution of the
cone concentrator, belongs to the class of nonimaging
concentrators: reaching concentration values very closet o those of
the ideal concentrator, and is able to concentrate and transfer
towards its outlet section almost the entire energy of the beams of
rays tapping on the opening, with an angle that is lower or the
same of the acceptance angle .theta. for which the concentrator was
designed.
[0006] The receiver, device designed to absorb the sun radiation,
is represented generally as a separate unit and, in its various
forms and embodiments, if positioned at the level of the ground, is
generally covered exactly by a nonimaging concentrator (very
frequently a CPC) having the task of increasing the density of
concentration. The receiver does not have any interaction with the
concentration system, without modifying, in any way, its
operation.
[0007] WO2014/038553 discloses a device for collecting solar energy
by means of a concentrator of the nonimaging type, wherein inside
the receiver is originated a fluidized bed of solid particles.
Solid particles are heated by means of exposure to concentrated sun
radiation and subsequently withdrawn and sent to a heat exchanger.
The fluidization gas is withdrawn separately from the solid
particles and sent to a heat exchanger for pre-heating of the same
gas fed to the fluidized bed.
[0008] In actual situations, nonimaging systems behave differently
with respect to the ideal situation. In fact, according to
experimental tests, a part of rays with an incidence angle that is
very close to the acceptance angle 8 have an inverse behavior
compared to that expected and generate transmission curves with
inflection points more or less accentuated.
[0009] Moreover, all the beams of rays with angle higher than the
acceptance angle .theta. are rejected and pass through the inlet
section abandoning the CPC.
[0010] The conveying of the solar rays in the NIO optics within the
limits of the acceptance angle results in the need for extremely
expensive pointing systems of sun radiation, with a consequent
increase in costs of the system.
[0011] There is therefore the need to improve the behavior of NIO
systems with respect to the transmission of sun radiation on to the
receiver, when the beams of rays arrive with an angle higher or
close to the acceptance angle.
[0012] In this context it is included the solution according to the
present invention, which aims to provide a new method and system to
optimize energy harvesting in a NIO system.
[0013] These and other results are obtained according to the
present invention by proposing to enter inside the volume delimited
by the NIO system, such as a CPC, in the opposite direction to that
of concentration, a fair number of solid particles, so that the
latter can intercept and absorb up to thermodynamic equilibrium and
during the multiple and random locations occupied in the fall or
ascent phase, the sun radiation that enters the CPC.
[0014] A purpose of the present invention is therefore to provide a
device for collecting solar energy by means of a concentrator of
the nonimaging (NIO) type suitably coupled with a receiver, which
allows to overcome the limitations of NIO systems according to the
prior art and to obtain the previously described technical
results.
[0015] A further aim of the invention is that said device for
collecting solar energy by means of a concentrator of the
nonimaging type can be made with low costs, with regard to both the
production costs and the management costs.
[0016] Another object of the invention is to propose a device for
collecting solar energy by means of a concentrator of the
nonimaging type that is simple, safe and reliable.
[0017] It is therefore a specific object of the present invention a
device for collecting solar energy by means of a concentrator of
the nonimaging type and a receiver for the transfer of energy by
heat exchange with a fluid which operates, independently, a
thermodynamic cycle for the exploitation of energy, said
concentrator comprising an inlet area, an underlying outlet area
and an inner space between said inlet area and said outlet area;
said receiver being positioned under said concentrator and said
inner space of the concentrator and said receiver being connected
by said outlet area, wherein said inner space of the concentrator
and said receiver are in fluid communication through said outlet
area, a plurality of solid particles are present inside said
receiver, and said device for collecting solar energy comprises
means apt to take a part of said solid particles from said receiver
and to put them from below inside said inner space of said
concentrator, said solid particles subsequently returning, by
gravity, into said receiver, passing through said outlet area.
[0018] In particular, according to the invention, said means apt to
take said solid particles from said receiver and to put them from
below inside said inner space of said concentrator comprise an
input device.
[0019] Preferably, according to the invention, said means apt to
take said solid particles from said receiver and to put them from
below inside said inner space of said concentrator are made of
streams of gases, vapours, or by a combination of the same, apt to
raise said solid particles up to a height comprised between said
inlet area and said outlet area of the concentrator.
[0020] More preferably, according to the invention, said receiver
and said means apt to take said solid particles from said receiver
and to put them from below inside said inner space of said
concentrator are made of a spouted bed.
[0021] In particular, according to the present invention, said
concentrator is a CPC concentrator (Compound Parabolic
Concentrator).
[0022] Finally, always according to the invention, said solid
particles are made of a material with high solar absorption and low
emissivity, such as metal-type oxides and, preferably, chromite
((Mg,Fe)(Cr,Al).sub.2O.sub.4).
[0023] It is evident the effectiveness of the device of the present
invention, which allows to intercept and absorb, by means of the
solid particles placed inside the volume delimited by the
nonimaging system, the sun radiation which enters in the same. By
modifying the amount, the height and the frequency of the jet of
particles, it is possible to do so that the particles can reach the
receiver progressively increasing their temperature, up to a level
such as to make efficient the heat exchange with another fluid
which operates, independently, a thermodynamic cycle for the
exploitation of energy.
[0024] Since, statically, the particles can be in some positions
occupied by beams of rays that, after a series of internal
reflections in the nonimaging system, would be thrown to the
outside, it is clear that the new device is able to modify the
energy performance of a traditional CPC concentrator or, more
generally, of any nonimaging concentrator.
[0025] The present invention will be now described, for
illustrative but not limitative purposes, according to its
preferred embodiment, with particular reference to the figures of
the accompanying drawings, in which:
[0026] FIG. 1 shows a sectional view of a CPC concentrator
according to the prior art, and
[0027] FIG. 2 shows a sectional view of a device for collecting
solar energy by means of a concentrator of the nonimaging type
according to the present invention, applied to a CPC
concentrator.
[0028] Making preliminarily reference to FIG. 1, in a solar
concentration system CPC, indicated as a whole by the reference
number 12, with an inlet area 1, an outlet area 2 and an acceptance
angle .theta., sun rays entering the inlet section with an angle
lower than .theta., such as for example the ray indicated by the
reference number 5, reach the outlet section 2 and the receiver 3;
on the contrary, the ray 4, which presents an angle of inlet
greater than that of acceptance, after a number of reflections on
the walls of the concentrator 12, is rejected and will never reach
the outlet section 2 and, consequently, the receiver 3.
[0029] In FIG. 2, a device for collecting solar energy by means of
a concentrator of the nonimaging type according to the present
invention, applied to the CPC concentrator 12 already shown with
reference to FIG. 1, without prejudice to the geometry of the CPC
12 and of the receiver 3, provides for an input devices 6 that
randomly introduce within the CPC 12 some solid particles 11 taken
from the inside of the receiver 3.
[0030] Solid particles 11 taken from the inside of the receiver 3
and introduced within the CPC 12 therefore occupy part of the empty
space delimited by the CPC 12. For example, the solid particle 8,
launched from the input device 6, following the trajectory 7,
intercepts the ray 4, with inlet angle higher than the acceptance
angle, absorbing all or part of the thermal energy and transporting
it, falling back, towards the receiver 3. If it had not been
intercepted by the solid particle 8, this energy would have been
lost, as already explained with reference to FIG. 1, disclosing the
operation of the CPCs according to the prior art.
[0031] In the same way, also the solid particle 10, launched from
the input device 6, following the trajectory 9, intercepts the ray
5, with inlet angle lower than the acceptance angle, absorbing all
or part of its thermal energy and transporting it, falling back,
towards the receiver 3, but in a way completely different from what
would happen in a CPC according to the prior art.
[0032] Other rays, with inlet angle lower than that of acceptance,
reach the receiver 3 and give thermal energy to the solid particles
that are located inside this receiver. Inside the receiver 3, to
optimize the heat exchange, the solid particles may advantageously
be kept in motion, for example by generation of a fluidized
bed.
[0033] It appears evident that, in a device for collecting solar
energy by means of a concentrator of the nonimaging type according
to the present invention, the operation of a CPC concentrator 12 is
deeply changed by the presence of the solid particles and that, as
a consequence, it is possible a great improvement of the system
performance, since such particles make it possible to absorb part
of the energy that, in a CPC concentrator according to the prior
art, would be surely lost.
[0034] It is also clear that the solid particles, during their
ascent and descent trajectory within the CPC 12, meet a large
number of rays and that the particles themselves, interacting
between them, can change the trajectory imposed on them by the
input device 6. Accordingly, the input device 6 is preferably
selected from those capable of ensuring a more uniform possible
movement of the particles 11 taken from the receiver 3.
[0035] Solid particles 11, according to the invention, will be
preferably made of material with high solar absorption and low
emissivity, but anyway they will be chosen according to the actual
operating conditions of the system as requested by the receiver 3
for energy recovery.
[0036] The input of the particles may be carried out in different
ways. A preferred embodiment provides for the use of a "spouted
bed" that, itself acting as receiver, allows to use the "fountain
of particles" that is created on top as a true ejector.
[0037] However, are also possible mechanical, fluidodynamic or
combined systems designed so that the particles do not exit from
the top of the CPC 12 or from another nonimaging system and occupy,
as far as possible, all the available volume.
[0038] The input process can be continuous or discontinuous and
therefore programmed to operate with a certain frequency.
[0039] By means of the device for collecting solar energy by means
of a concentrator of the nonimaging type according to the present
invention it is then created a multifocus system, able of
differently the thermal energy transmitted and focused by a
traditional NIO system or, in particular, by a CPC.
[0040] In conclusion, the invention can be summarized as a
nonimaging system the internal volume of which is partially
occupied by a series of solid particles, introduced from the outlet
section of the NIO system, able to absorb the sun radiation
entering the NIO system, independently from the acceptance
angle.
[0041] The present invention has been described for illustrative
but not limitative purposes, according to its preferred
embodiments, but it is to be understood that variations and/or
modifications may be made by those skilled in the art without
departing from the relative scope of protection, as defined by the
enclosed claims.
* * * * *