U.S. patent application number 14/237885 was filed with the patent office on 2014-07-10 for thermal energy storage and recovery arrangement.
This patent application is currently assigned to SIEMENS AKTIENGESELLSCHAFT. The applicant listed for this patent is Hans Laurberg. Invention is credited to Hans Laurberg.
Application Number | 20140190659 14/237885 |
Document ID | / |
Family ID | 46785420 |
Filed Date | 2014-07-10 |
United States Patent
Application |
20140190659 |
Kind Code |
A1 |
Laurberg; Hans |
July 10, 2014 |
THERMAL ENERGY STORAGE AND RECOVERY ARRANGEMENT
Abstract
A thermal energy storage and recovery arrangement is provided.
The arrangement has a first thermal energy storage, a compression
and expansion unit coupled thereto, and a second thermal energy
storage coupled to the compression and expansion unit. The first
and second thermal energy storage are adapted to work at a
temperature equal to or higher than ambient temperature. In a
charging mode, the first thermal energy storage is adapted for
receiving and releasing thermal energy to a received working
medium. The compression and expansion unit is adapted for receiving
and compressing the working medium from the first thermal energy
storage. The second thermal energy storage is adapted for receiving
the compressed working medium and thermal energy therefrom and
storing at least part of this energy. The compression and expansion
unit is adapted for receiving the compressed working medium from
the second thermal energy storage and expanding the compressed
working medium.
Inventors: |
Laurberg; Hans; (Arhus C,
DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Laurberg; Hans |
Arhus C |
|
DK |
|
|
Assignee: |
SIEMENS AKTIENGESELLSCHAFT
Munich
DE
|
Family ID: |
46785420 |
Appl. No.: |
14/237885 |
Filed: |
September 3, 2012 |
PCT Filed: |
September 3, 2012 |
PCT NO: |
PCT/EP2012/067120 |
371 Date: |
March 7, 2014 |
Current U.S.
Class: |
165/10 |
Current CPC
Class: |
Y02E 60/142 20130101;
F28D 20/0034 20130101; F28D 20/00 20130101; Y02E 60/14
20130101 |
Class at
Publication: |
165/10 |
International
Class: |
F28D 20/00 20060101
F28D020/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 15, 2011 |
EP |
11181344.0 |
Claims
1. A thermal energy storage and recovery arrangement, the
arrangement comprising a first thermal energy storage, a
compression and expansion unit coupled to the first thermal energy
storage, and a second thermal energy storage coupled to the
compression and expansion unit, wherein, in a charging mode, the
first thermal energy storage is adapted for receiving a working
medium being supplied to the thermal energy storage and recovery
arrangement and for releasing thermal energy to the received
working medium, the compression and expansion unit is adapted for
receiving the working medium from the first thermal energy storage
and for compressing the working medium, the second thermal energy
storage is adapted for receiving the compressed working medium from
the compression and expansion unit, for receiving thermal energy
from the compressed working medium and for storing at least a part
of this energy, and the compression and expansion unit is adapted
for receiving the compressed working medium from the second thermal
energy storage and for expanding the compressed working medium,
wherein the first thermal energy storage and the second thermal
energy storage are adapted to work at a temperature being equal to
or higher than the ambient temperature of the thermal energy
storage and recovery arrangement.
2. The thermal energy storage and recovery arrangement as set forth
in claim 1, wherein, in a discharging mode, the compression and
expansion unit is adapted for receiving a working medium and for
compressing the received working medium, the second thermal energy
storage is adapted for receiving the compressed working medium from
the compression and expansion unit and for releasing thermal energy
to the compressed working medium, the compression and expansion
unit is adapted for receiving the compressed working medium from
the second thermal energy storage and for expanding the compressed
working medium, and the first thermal energy storage is adapted for
receiving the expanded working medium from the compression and
expansion unit, for receiving thermal energy from the expanded
working medium, for storing at least a part of this energy and for
outputting the working medium.
3. The thermal energy storage and recovery arrangement as set forth
in claim 1, wherein the first thermal energy storage is adapted to
work at a first pressure, and the second thermal energy storage is
adapted to work at a second pressure being higher than the first
pressure, wherein the first pressure corresponds to an ambient
pressure of the thermal energy storage and recovery
arrangement.
4. The thermal energy storage and recovery arrangement as set forth
in claim 1, wherein the compression and expansion unit comprises at
least one compression means and at least one expansion means.
5. The thermal energy storage and recovery arrangement as set forth
in claim 1, further comprising a heat exchanging device, wherein a
first side of the heat exchanging device is coupled between the
compression and expansion unit and the first thermal energy
storage.
6. The thermal energy storage and recovery arrangement as set forth
in claim 5, wherein the first side of the heat exchanging device is
coupled between an expansion means of the compression and expansion
unit and the first thermal energy storage, and wherein a second
side of the heat exchanging device is coupled to an external
device.
7. The thermal energy storage and recovery arrangement as set forth
in claim 5, wherein the first side of the heat exchanging device is
coupled between a compression means of the compression and
expansion unit and the first thermal energy storage, and wherein a
second side of the heat exchanging device is coupled between the
second thermal energy storage and an expansion means of the
compression and expansion unit.
8. The thermal energy storage and recovery arrangement as set forth
in claim 1, wherein the working medium is gas.
9. The thermal energy storage and recovery arrangement as set forth
in claim 1, wherein the first thermal energy storage comprises a
liquid medium as storage material.
10. The thermal energy storage and recovery arrangement as set
forth in claim 1, wherein the temperature of the medium being
supplied to the system corresponds to an ambient temperature of the
thermal energy storage and recovery arrangement.
11. A thermal energy storage and recovery system comprising a
thermal energy storage and recovery arrangement as set forth in
claim 1, and a heat consumption arrangement, which is connected
directly or indirectly to the thermal energy storage and recovery
arrangement and which is adapted to receive thermal energy from the
medium of the thermal energy storage and recovery arrangement.
12. The thermal energy storage and recovery system as set forth in
claim 11, wherein the heat consumption arrangement comprises a
district heating installation system.
13. The thermal energy storage and recovery system as set forth in
claim 11, wherein the first thermal energy storage is part of the
district heating installation system.
14. A method for storing and recovering thermal energy in a thermal
energy storage and recovery arrangement, the method comprising in a
charging mode, receiving, by a first thermal energy storage, a
working medium being supplied to the thermal energy storage and
recovery arrangement and releasing, by the first thermal energy
storage, thermal energy to the received working medium, receiving,
by a compression and expansion unit coupled to the first thermal
energy storage, the working medium from the first thermal energy
storage and compressing, by the compression and expansion unit, the
working medium, receiving, by a second thermal energy storage
coupled to the compression and expansion unit, the compressed
working medium from the compression and expansion unit, receiving,
by the second thermal energy storage, thermal energy from the
compressed working medium and storing at least a part of this
energy in the second thermal energy storage, and receiving, by the
compression and expansion unit, the compressed working medium from
the second thermal energy storage and expanding, by the compression
and expansion unit, the compressed working medium, wherein the
first thermal energy storage and the second thermal energy storage
are adapted to work at a temperature being equal to or higher than
the ambient temperature of the thermal energy storage and recovery
arrangement.
15. The thermal energy storage and recovery arrangement as set
forth in claim 8, wherein the working medium is gas comprising
air.
16. The thermal energy storage and recovery arrangement as set
forth in claim 9, wherein the first thermal energy storage
comprises a liquid medium as storage material, wherein the liquid
medium comprises water.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US National Stage of International
Application No. PCT/EP2012/067120 filed Sep. 3, 2012, and claims
the benefit thereof. The International Application claims the
benefit of European Application No. EP11181344 filed Sep. 15, 2011.
All of the applications are incorporated by reference herein in
their entirety.
FIELD OF INVENTION
[0002] The present invention relates to the field of temporarily
storing thermal energy. In particular, the present invention
relates to a thermal energy storage and recovery arrangement
comprising two thermal energy storages and a compression and
expansion unit. Further, the present invention relates to a thermal
energy storage and recovery system comprising such a thermal energy
storage and recovery arrangement. Moreover, the present invention
relates to a method for storing and recovering thermal energy.
ART BACKGROUND
[0003] The production of electric power from various types of
alternative energy sources such as for instance wind turbines,
solar power plants and wave energy plants is not continuous. The
production may be dependent on environmental parameters such as for
instance wind speed (for wind turbines), sunshine intensity (for
solar power plant) and wave height and direction (for wave energy
plants). There is very often little or no correlation between
energy production and energy demand.
[0004] One known approach to solve the problem of uncorrelated
electric power production and electric power demand is to
temporally store energy, which has been produced but which has not
been demanded, and to release the stored energy at times at which
there is a high demand. In the past there have been suggested many
different methods to temporarily store energy. Suggested methods
are for instance (a) mechanical energy storage methods e.g. pumped
hydro storage, compressed air storage and flywheels, (b) chemical
energy storage methods e.g. electrochemical batteries and organic
molecular storage, (c) magnetic energy storage, and (d) thermal
energy storage.
[0005] US 2010/0251711 A1 discloses an apparatus for storing
energy. The apparatus includes a compression chamber for receiving
a gas, a compression piston for compressing gas contained in the
compression chamber, a first heat store for receiving and storing
thermal energy from gas compressed by the compression piston, an
expansion chamber for receiving gas after exposure to the first
heat store, an expansion piston for expanding gas received in the
expansion chamber, and a second heat store for transferring thermal
energy to gas expanded by the expansion piston. Thus, an energy
storage apparatus is provided in which first and second heat
storage means are placed within a thermal heat pump cycle to
produce a hot and cold store respectively during charging. Energy
is then recoverable in a discharging mode by passing gas through
the cooled second heat storage means, compressing gas cooled by the
second heat storage means, heating the cooled compressed gas by
exposing the gas to the heated first heat storage means, and
allowing the heated gas to expand by doing work on generator means.
However, using cold storages induces some challenges on the used
machinery.
[0006] There may be a need for improving the temporal storage of
thermal energy in particular with respect to the implementation and
the efficiency of a thermal energy storage and recovery system.
SUMMARY OF THE INVENTION
[0007] This need may be met by the subject matter described herein.
Advantageous embodiments of the present invention are further
described herein.
[0008] According to a first aspect of the invention, a thermal
energy storage and recovery arrangement is provided. The
arrangement comprises a first thermal energy storage, a compression
and expansion unit coupled to the first thermal energy storage, and
a second thermal energy storage coupled to the compression and
expansion unit. In a charging mode, the first thermal energy
storage is adapted for receiving a working medium being supplied to
the thermal energy storage and recovery arrangement and for
releasing thermal energy to the received working medium, the
compression and expansion unit is adapted for receiving the working
medium from the first thermal energy storage and for compressing
the working medium, the second thermal energy storage is adapted
for receiving the compressed working medium from the compression
and expansion unit, for receiving thermal energy from the
compressed working medium and for storing at least a part of this
energy, and the compression and expansion unit is adapted for
receiving the compressed working medium from the second thermal
energy storage and for expanding the compressed working medium. The
first thermal energy storage and the second thermal energy storage
are adapted to work at a temperature being equal to or higher than
the ambient temperature of the thermal energy storage and recovery
arrangement.
[0009] One of the basic ideas of the invention is to provide a
thermal energy storage and recovery arrangement using standard
components.
[0010] The term "thermal energy storage" may denote any kind of
storage being able to store thermal energy, for example for later
use. The storages may be employed to balance energy demand between
day time and night time.
[0011] The first thermal energy storage and the second thermal
energy storage may be hot storages. The term "hot storage" may
denote any storage working at a temperature above or at ambient
temperature. The ambient temperature may denote the temperature of
the surrounding medium. "Working at or above ambient temperature"
may denote that the storage receives the working medium at or above
ambient temperature and outputs the working medium at or above
ambient temperature.
[0012] The term "compression and expansion unit" may denote any
kind of unit being able to compress and to expand the working
medium. When compressing the working medium, the pressure of the
working medium may become higher. When expanding the working
medium, the pressure of the working medium may become lower.
[0013] The working medium may be any kind of medium, fluid or
gaseous medium, being suitable to be used in such an energy storage
and recovery arrangement.
[0014] The different elements of the arrangement, i.e. storages and
compression and expansion unit, may be coupled for example via
pipes, for providing a thermally coupling between the elements of
the arrangement.
[0015] The term "charging mode" may denote an operational mode of
the arrangement, wherein energy, e.g. thermal energy, is stored
into the arrangement.
[0016] When using cold materials or mediums, a huge amount of
humidity may occur, for instance caused by condensed water, which
may also lead to creation of ice. This leads to specific
requirements of the material used for the storages and connection
pipes. By using storages (hot storages) working at a temperature at
or above ambient temperature, these requirements may be
decreased.
[0017] According to an embodiment of the invention, in a
discharging mode, the compression and expansion unit is adapted for
receiving a working medium and for compressing the received working
medium, the second thermal energy storage is adapted for receiving
the compressed working medium from the compression and expansion
unit and for releasing thermal energy to the compressed working
medium, the compression and expansion unit is adapted for receiving
the compressed working medium from the second thermal energy
storage and for expanding the compressed working medium, and the
first thermal energy storage is adapted for receiving the expanded
working medium from the compression and expansion unit, for
receiving thermal energy from the expanded working medium, for
storing at least a part of this energy and and for outputting the
working medium.
[0018] The term "discharging mode" may denote an operational mode
of the arrangement, wherein energy, e.g. thermal energy, is
extracted from the arrangement.
[0019] The thermal energy storage and recovery arrangement may be
operated in both directions, i.e. in a charging and in a
discharging mode. The same components may be used for both
modes.
[0020] According to a further embodiment of the invention, the
first thermal energy storage is adapted to work at a first
pressure, and the second thermal energy storage is adapted to work
at a second pressure being higher than the first pressure, wherein
the first pressure corresponds to an ambient pressure of the
thermal energy storage and recovery arrangement.
[0021] Thus, the first thermal energy storage may be a
"non-pressure" storage. This means that the pressure in this
storage is equal to the pressure of the working medium when
inputted to the arrangement, i.e. is equal to the ambient
pressure.
[0022] According to a further embodiment of the invention, the
compression and expansion unit comprises at least one compression
means and at least one expansion means.
[0023] The at least one compression means may be a compressor. A
compressor may be a mechanical device that increases the pressure
of medium flowing through the compressor by reducing its volume.
Such a compressor may be for example a gas compressor. The
compressor may be further adapted to transport the medium through a
pipe.
[0024] The at least one expansion means may be an expander, for
example a turbo-expander or expansion turbine. The expander may be
connected with the compressor via a shaft.
[0025] The expander may be adapted to expand the working medium
flowing through the expander, thereby producing work which may be
used to drive the compressor via the shaft or to drive a generator
coupled to the shaft. When expanding the working medium, the
pressure of the working medium will be decreased.
[0026] According to a further embodiment of the invention, the
thermal energy storage and recovery arrangement further comprises a
heat exchanging device, wherein a first side of the heat exchanging
device is coupled between the compression and expansion unit and
the first thermal energy storage.
[0027] By using a heat exchanging device, the same working medium
may be recycled and used within a closed cycle.
[0028] According to a further embodiment of the invention, the
first side of the heat exchanging device is coupled between an
expansion means of the compression and expansion unit and the first
thermal energy storage, and wherein a second side of the heat
exchanging device is coupled to an external device.
[0029] An external cycle or device may be coupled to the thermal
energy storage and recovery arrangement. The external device may be
for example a district heating system.
[0030] According to a further embodiment of the invention, the
first side of the heat exchanging device is coupled between a
compression means of the compression and expansion unit and the
first thermal energy storage, and wherein a second side of the heat
exchanging device is coupled between the second thermal energy
storage and an expansion means of the compression and expansion
unit.
[0031] According to this embodiment, the maximal temperature of the
first thermal energy storage may be chosen lower than the input
temperature for the compression and expansion unit. This may lead
to a smaller temperature range within the two energy storages.
Small temperature ranges may lead to less material problems as the
materials of the storages do not have to withstand extreme or at
least cold temperatures and at the same time extreme hot
temperatures.
[0032] According to a further embodiment of the invention, the
working medium is gas, in particular air.
[0033] Waste heat may leave the arrangement after expansion and may
have a pressure according to the ambient pressure. In this case,
for example the surrounding air may be used as the working
medium.
[0034] According to a further embodiment of the invention, the
first thermal energy storage comprises a liquid medium as storage
material, in particular wherein the liquid medium is water.
[0035] In particular when the temperature range of the storages is
lower by using heat exchanging devices, the heating or storage
material may be water. Water is an extremely cheap material and
comprises a heat capacity that is for example higher than that of
stones. Thus, the storage may be made smaller.
[0036] According to a further embodiment of the invention, the
temperature of the medium being supplied to the system corresponds
to an ambient temperature of the thermal energy storage and
recovery arrangement.
[0037] Thus, the arrangement may use directly the surrounding
air.
[0038] According to a second aspect of the invention, a thermal
energy storage and recovery system is provided. The thermal energy
storage and recovery system comprises a thermal energy storage and
recovery arrangement having the above mentioned features and a heat
consumption arrangement, which is connected directly or indirectly
to the thermal energy storage and recovery arrangement and which is
adapted to receive thermal energy from the medium of the thermal
energy storage and recovery arrangement.
[0039] The heat consumption arrangement may be connected via pipes
to the thermal energy storage and recovery arrangement. The heat
consumption arrangement may provide a heat transfer medium to the
thermal energy storage and recovery arrangement as well as receive
a heat transfer medium from the thermal energy storage and recovery
arrangement. The medium may provide the thermal energy.
[0040] According to an embodiment of the invention, the heat
consumption arrangement comprises a district heating installation
system.
[0041] The district heating installation system may receive the
heat transfer medium from the thermal energy storage and recovery
arrangement and may provide the heat transfer medium to the thermal
energy storage and recovery arrangement. The district heating
installation system may comprise a heat exchanger system which
thermally connects the heat transfer medium with a fluid such as
for instance water. Thereby, the district heating installation may
receive comparatively cold water from a water installation via a
water inlet and may provide hot or warm water to the water
installation via a water outlet.
[0042] According to a further embodiment of the invention the
thermal energy storage and recovery system further comprises a
control unit, which is connected to at least one of the thermal
energy storage and recovery arrangement and the heat consumption
arrangement. The control unit is adapted to control the operation
of the thermal energy storage and recovery system.
[0043] According to an embodiment of the invention, the first
thermal energy storage is part of the district heating installation
system.
[0044] In this case, it might be not necessary to build a separate
storage for the thermal energy storage and recovery arrangement,
but to reuse an existing storage of the district heating
installation system.
[0045] In one embodiment of the thermal energy storage and recovery
arrangement, for the discharge cycle, the compressor part of the
compression and expansion unit may be equipped with a cooling unit.
Thus, the pressure created by the compressor may be created without
temperature increase. The pressurized medium, for instance gas, may
be later heated by the district heating installation system.
[0046] It should be understood that features (individually or in
any combination) disclosed, described, used for or mentioned in
respect to the description of an embodiment of an thermal energy
storage and recovery arrangement may also be (individually or in
any combination) applied, used for, or employed for a method for
storing and recovering thermal energy in a thermal energy storage
and recovery arrangement.
[0047] According to a third aspect of the invention, a method for
storing and recovering thermal energy in a thermal energy storage
and recovery arrangement is provided. The method comprises in a
charging mode, receiving, by a first thermal energy storage, a
working medium being supplied to the thermal energy storage and
recovery arrangement and releasing, by the first thermal energy
storage, thermal energy to the received working medium, receiving,
by a compression and expansion unit coupled to the first thermal
energy storage, the working medium from the first thermal energy
storage and compressing, by the compression and expansion unit, the
working medium, receiving, by a second thermal energy storage
coupled to the compression and expansion unit, the compressed
working medium from the compression and expansion unit, receiving,
by the second thermal energy storage, thermal energy from the
compressed working medium and storing at least a part of this
energy in the second thermal energy storage, and receiving, by the
compression and expansion unit, the compressed working medium from
the second thermal energy storage and expanding, by the compression
and expansion unit, the compressed working medium, wherein the
first thermal energy storage and the second thermal energy storage
are adapted to work at a temperature being equal to or higher than
the ambient temperature of the thermal energy storage and recovery
arrangement.
[0048] According to a further aspect of the invention, there is
provided a computer program for storing and recovering thermal
energy in a thermal energy storage and recovery arrangement. The
computer program, when being executed by a data processor, is
adapted for controlling the method as described above.
[0049] As used herein, reference to a computer program is intended
to be equivalent to a reference to a program element containing
instructions for controlling a computer system to coordinate the
performance of the above described method.
[0050] The computer program may be implemented as computer readable
instruction code in any suitable programming language, such as, for
example, JAVA, C++, and may be stored on a non-transitory
computer-readable medium (removable disk, volatile or non-volatile
memory, embedded memory/processor, etc.). The instruction code is
operable to program a computer or any other programmable device to
carry out the intended functions. The computer program may be
available from a network, such as the World Wide Web, from which it
may be downloaded.
[0051] The invention may be realized by means of a computer program
respectively software. However, the invention may also be realized
by means of one or more specific electronic circuits respectively
hardware. Furthermore, the invention may also be realized in a
hybrid form, i.e. in a combination of software modules and hardware
modules.
[0052] According to a further aspect of the invention there is
provided a non-transitory computer-readable medium (for instance a
CD, a DVD, a USB stick, a floppy disk or a hard disk), in which a
computer program for storing and recovering thermal energy in a
thermal energy storage and recovery arrangement is stored, which
computer program, when being executed by a processor, is adapted to
carry out or control a method for storing and recovering thermal
energy in a thermal energy storage and recovery arrangement.
[0053] It has to be noted that embodiments of the invention have
been described with reference to different subject matters. In
particular, some embodiments have been described with reference to
method type claims whereas other embodiments have been described
with reference to apparatus type claims. However, a person skilled
in the art will gather from the above and the following description
that, unless other notified, in addition to any combination of
features belonging to one type of subject matter also any
combination between features relating to different subject matters,
in particular between features of the method type claims and
features of the apparatus type claims is considered as to be
disclosed with this document.
[0054] The aspects defined above and further aspects of the present
invention are apparent from the examples of embodiment to be
described hereinafter and are explained with reference to the
examples of embodiment. The invention will be described in more
detail hereinafter with reference to examples of embodiment but to
which the invention is not limited.
BRIEF DESCRIPTION OF THE DRAWINGS
[0055] Embodiments of the present invention are now described with
reference to the accompanying drawings to which the invention is
not limited.
[0056] FIG. 1 illustrates a thermal energy storage and recovery
arrangement according to an embodiment;
[0057] FIG. 2 illustrates a thermal energy storage and recovery
arrangement in charging mode according to an embodiment;
[0058] FIG. 3 illustrates the thermal energy storage and recovery
arrangement of FIG. 2 in discharging mode according to an
embodiment;
[0059] FIG. 4 illustrates the thermal energy storage and recovery
arrangement according to an embodiment;
[0060] FIG. 5 illustrates the thermal energy storage and recovery
arrangement according to an embodiment.
DETAILED DESCRIPTION
[0061] The illustration in the drawings is in schematic form. It is
noted that in different figures, similar or identical elements are
provided with the same reference signs.
[0062] In FIG. 1, a thermal energy storage and recovery arrangement
100 according to an embodiment is shown. The thermal energy storage
and recovery arrangement comprises a first thermal energy storage
101 and a second thermal energy storage 103. The first thermal
energy storage is adapted to work at a temperature being equal to
or higher than the ambient temperature. This means that the first
thermal energy storage receives a working medium having a
temperature equal to or higher than the ambient temperature and
releases the working medium at a temperature equal to or higher
than the ambient temperature. In one embodiment, the first thermal
energy storage is adapted to receive as an input a working medium
having ambient temperature and having ambient pressure. The second
thermal energy storage is also adapted to work at a temperature
being equal to or higher than the ambient temperature.
[0063] The thermal energy storage and recovery arrangement
comprises further a compression and expansion unit 102. The
compression and expansion unit is coupled to the first thermal
energy storage and the second thermal energy storage.
[0064] In a charging mode, the first thermal energy storage
receives a working medium being supplied to the thermal energy
storage and recovery arrangement. Further, it releases thermal
energy, stored in the first thermal energy storage, to the received
working.
[0065] Subsequently, the compression and expansion unit receives
the working medium from the first thermal energy storage and
compresses the working medium. Then, the second thermal energy
storage receives the compressed working medium from the compression
and expansion unit, receives thermal energy from the compressed
working medium and stores at least a part of this energy. Following
to that, the compression and expansion unit receives the compressed
working medium from the second thermal energy storage and expands
the compressed working medium.
[0066] In a discharging mode, the compression and expansion unit
102 receives a working medium and compresses the received working
medium. Then, the second thermal energy storage 103 receives the
compressed working medium from the compression and expansion unit
and releases thermal energy to the compressed working medium.
Subsequently, the compression and expansion unit receives the
compressed working medium from the second thermal energy storage
and expands the compressed working medium. Then, the first thermal
energy storage 101 receives the expanded working medium from the
compression and expansion unit, receives thermal energy from the
expanded working medium and outputs the working medium, for example
to a district heating installation system.
[0067] FIG. 2 shows charge cycle of a thermal energy storage and
recovery arrangement 200 according to an embodiment.
[0068] First, a first thermal energy storage 101 receives a working
medium, for example air, at an ambient temperature and normal
pressure. In the first thermal energy storage 101, energy is
released to the working medium as heat in the thermal energy
storage. When being output from the first thermal energy storage,
the working medium is above ambient temperature and comprises
normal pressure.
[0069] The working medium is then input to a compression means 204
of the compression and expansion unit. When being output by the
compression means, the working medium has a higher temperature and
a higher pressure, as the compression means 204 compresses the
medium and heats it during compression. This may be the maximum
temperature and maximum pressure within the arrangement.
[0070] The working medium is then input to a second thermal energy
storage 103. When being output by the second storage, the working
medium is at a lower temperature than at the input to the second
storage, but is for instance higher than ambient temperature, and
has the same pressure. Energy is stored as heat in the second
storage 103.
[0071] After this, the working medium is supplied to an expansion
means 206 of the compression and expansion unit. The expansion
means may be coupled to the compression means by a shaft 205. At
the output of the expansion means, the working medium is at a lower
temperature than at the input to the expansion means but at a
higher temperature than at the input to the first thermal energy
storage and has a normal pressure (as the expander 206 expands the
medium and cools it down). At this point, waste heat may be removed
from the arrangement.
[0072] FIG. 3 shows the thermal energy storage and recovery
arrangement of FIG. 2 in discharging mode according to an
embodiment, In this case, the arrangement 300 comprises a
compression means 306 and an expansion means 304, coupled via a
shaft 305, which are interchanged compared to FIG. 2.
[0073] The temperatures and pressures do not have to be same as
compared to FIG. 2. The output of the first thermal energy storage
may be at ambient temperature and normal or ambient pressure.
[0074] The compression means and expansion means 204, 206 and 304,
306 may be one single unit. They may also be four separate
units.
[0075] FIG. 4 shows a thermal energy storage and recovery
arrangement 400 according to a further embodiment. In this case,
the first thermal energy storage 101 is coupled to the expansion
means 206 via a heat exchanging device 407. The heat exchanging
device may be coupled to an external device.
[0076] By using such a configuration, the same working medium (for
example air) may be reused or recycled. In a discharging mode, the
first thermal energy storage 101 would be coupled to a compression
means via the heat exchanging device.
[0077] FIG. 5 illustrates a thermal energy storage and recovery
arrangement 500 according to a further embodiment.
[0078] According to this embodiment, the output of the second
thermal energy storage 103 is coupled to a first side of a heat
exchanging device 508. The first side of the heat exchanging device
is further coupled to the expansion means 206. The output of the
expansion means is coupled to the input of the first thermal energy
storage 101. The output of the first thermal energy storage is
coupled to a second side of the heat exchanging device 508. The
second side of the heat exchanging device is further coupled to the
input of the compression means.
[0079] By using such a configuration, the maximum temperature of
the "non pressure storage", i.e. the first storage device, can be
chosen lower than the input temperature for the compressor by
inserting the heat exchanger. For example, as shown in FIGS. 1 to
3, the large temperature drop in the storages leads to high
temperature lost and larger wear on the heat material. By using a
configuration as shown in FIG. 5, the compressor/expander may see
the same temperatures as before but the temperature change in each
storage may be highly reduced.
[0080] The thermal energy storage and recovery system according to
embodiments of the invention may provide the following
features:
[0081] No cold storage might be needed. By using two hot storages,
the expander in the charging mode may create more power than the
compressor in the discharging.
[0082] The proposed arrangement may be easier produced as there is
no machinery that has to work with cold material.
[0083] The temperature of the first thermal energy (non-pressured)
storage can be chosen to be the ambient temperature and the
temperature for district heating. Thus, the district heating system
can be used as the storage (no storage needs to be build). Further,
in the discharge cycle, the compressor can be build with a cooler
such that pressure may be made without temperature increase--later
the pressurized gas can be heated by the district heating.
[0084] The temperature difference of the storages input/output
(t_difference) may be smaller than in common systems. The equation
of the temperature loss (t.sub.-- loss) in a storage may be given
by
t_loss=Constant*t_difference,
where Constant is constant for every storage given a specific
inflow speed. From this equation it may be seen that the
temperature losses is smaller than in common systems.
[0085] The waste heat may be at ambient temperature. Thus, it may
be possible to make an implementation where the surrounding air is
used in the system. This may save an additional heat exchanger in
the system for releasing the waste heat.
[0086] Due to the temperature range of the first storage, it may be
possible to construct this storage with water as heating material.
Water is both an extremely cheap material and it have a heat
capacity that is for instance double of stones (the storage need
only to be half the size).
[0087] It should be noted that the term "comprising" does not
exclude other elements or steps and "a" or "an" does not exclude a
plurality. Also elements described in association with different
embodiments may be combined. It should also be noted that reference
signs in the claims should not be construed as limiting the scope
of the claims.
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