U.S. patent application number 10/155356 was filed with the patent office on 2002-12-19 for thermal storge medium using a hydrate and apparatus thereof, and method for producing the thermal storage medium.
This patent application is currently assigned to NKK CORPORATION. Invention is credited to Fukushima, Shinichiro, Matsumoto, Shigenori, Ogoshi, Hidemasa, Takao, Shingo.
Application Number | 20020189277 10/155356 |
Document ID | / |
Family ID | 27480547 |
Filed Date | 2002-12-19 |
United States Patent
Application |
20020189277 |
Kind Code |
A1 |
Takao, Shingo ; et
al. |
December 19, 2002 |
Thermal storge medium using a hydrate and apparatus thereof, and
method for producing the thermal storage medium
Abstract
The best mode aims to provide a thermal storage medium that
improves the efficiency of heat exchange between the thermal
storage medium and the cooling medium liquid in the cooling medium
body, and that prevents supercool of the aqueous solution which
produces hydrate. A large thermal storage capacity is attained
using the latent heat of hydrate in the cooling medium body. By
forming slurry of hydrate, the fluidability of the hydrate
increases the efficiency of the heat exchange with cooling medium
liquid. By sealing fine particles in the cooling medium body, the
super-cool of aqueous solution is prevented. By changing position
of the cooling medium body or by other means, the aqueous solution
is agitated to keep the fine particles disperse and float in the
aqueous solution, thus preventing the degradation of effect to
prevent supercooling. Furthermore, a method for producing hydrate
cooling medium body that can be generated at higher temperatures
than the temperature of ice without using a thermal storage medium
is suitably used in thermal storage system such as air-conditioners
without using a special coolant.
Inventors: |
Takao, Shingo; (Kuki,
JP) ; Ogoshi, Hidemasa; (Yokohama, JP) ;
Fukushima, Shinichiro; (Yokohama, JP) ; Matsumoto,
Shigenori; (Kawasaki, JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
767 THIRD AVENUE
25TH FLOOR
NEW YORK
NY
10017-2023
US
|
Assignee: |
NKK CORPORATION
Tokyo
JP
|
Family ID: |
27480547 |
Appl. No.: |
10/155356 |
Filed: |
May 23, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10155356 |
May 23, 2002 |
|
|
|
PCT/JP00/08272 |
Nov 24, 2000 |
|
|
|
Current U.S.
Class: |
62/430 ; 252/67;
252/71; 62/434 |
Current CPC
Class: |
C09K 5/00 20130101; F28D
20/02 20130101; Y02E 60/14 20130101; Y02P 20/10 20151101; F28D
20/021 20130101; F28F 13/125 20130101; C09K 5/066 20130101; F28D
20/023 20130101 |
Class at
Publication: |
62/430 ; 252/67;
252/71; 62/434 |
International
Class: |
F25D 001/00; C09K
005/00; C10M 101/00; F25D 011/00; F25D 017/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 26, 1999 |
JP |
11-336170 |
Dec 20, 1999 |
JP |
11-361179 |
Aug 15, 2000 |
JP |
2000-246333 |
Aug 15, 2000 |
JP |
2000-246335 |
Claims
What is claimed is:
1. A thermal storage apparatus for using a hydrate thermal storage
medium comprising: a storage tank for storing a cooling medium
liquid; a refrigerating machine, connected with the storage tank
via a pipe for cooling the cooling medium liquid, the cooling
medium liquid circulating between the storage tank and the
refrigerating machine; a thermal storage body immersed in the
cooling medium liquid, wherein the thermal storage medium
comprising, a hermetically sealed container, an aqueous solution
filled in the hermetically sealed container, to generate at least
one selected from the group consisting of a primary hydrate and a
secondary hydrate, wherein the primary hydrate has smaller
hydration number and smaller heat capacity than the secondary
hydrate, the secondary hydrate has larger hydration number and
larger heat capacity than the primary hydrate, fine particles to
prevent the aqueous solution from super-cooling, the fine particles
being contained in the hermetically sealed container.
2. The thermal storage apparatus according to claim 1, further
comprising container drive means for changing position of the
container and moving the container in the cooling medium liquid to
disperse the fine particles in the container.
3. The thermal storage apparatus according to claim 2, wherein the
container drive means comprises a fluid mechanism to change
position of the container or to move the container by fluidizing
the cooling medium liquid in the storage tank.
4. The thermal storage apparatus according to claim 2, wherein the
container drive means comprises an air-injection mechanism to
change position of the container or to move the container by
injecting air into the cooling medium liquid in the storage tank
and by ascending air bubbles.
5. The thermal storage apparatus according to claim 2, wherein the
container drive means comprises a mechanical drive mechanism for
mechanically changing position of the container or moving the
container.
6. The thermal storage apparatus according to claim 1, wherein the
container of the thermal storage medium floats freely in the
cooling medium liquid in the storage tank.
7. The thermal storage apparatus according to claim 1, wherein the
container of the thermal storage medium is supported in the storage
tank in a free-rotational mode.
8. The thermal storage apparatus according to claim 1, wherein the
container of the storage tank provides at least one piece of blade
members outside of the container, to promote changing position of
the container or moving the container.
9. The thermal storage apparatus according to claim 1, wherein the
aqueous solution filled in the hermetically sealed container
contains a guest compound, where the generation temperature of at
least one selected from the group consisting of the primary hydrate
and the secondary hydrate varies in accordance with the
concentration of the aqueous solution.
10. The thermal storage apparatus according to claim 1, wherein the
fine particles have a diameter size of 100 .mu.m or less.
11. The thermal storage apparatus according to claim 1, wherein the
fine particles have a diameter size of 10 .mu.m or less.
12. The thermal storage apparatus according to claim 1, wherein the
fine particles have a diameter size of 100 .mu.m or less, and the
fine particles in the aqueous solution have a concentration of 0.1
mg/l or more.
13. A hydrate thermal storage medium comprising: an aqueous
solution containing a guest compound to generate a hydrate slurry
by cooling; and, a corrosion inhibitor.
14. The hydrate thermal storage medium according to claim 13,
wherein the contained corrosion inhibitor is 5,000 wt.ppm or less
of concentration.
15. The hydrate thermal storage medium according to claim 13,
wherein the guest compound is one selected from the group
consisting of a tetra-n-butylammonium salt, a
tetra-iso-amylammonium salt, a tetra-iso-butylphosphonium salt, and
a tri-iso-amylsulfonium salt.
16. A method for producing a hydrate thermal storage medium
comprising the steps of: (a) preparing an aqueous solution
containing a guest compound to generate at least one selected from
the group consisting of a primary hydrate and a secondary hydrate,
wherein the primary hydrate has smaller hydration number and
smaller heat capacity than the secondary hydrate, the secondary
hydrate has larger hydration number and larger heat capacity than
the primary hydrate; and, (b) cooling the aqueous solution to
produce at least one selected from the group consisting of the
primary hydrate and the secondary hydrate.
17. The method according to claim 16, wherein the aqueous solution
is cooled at a rate of 6 kcal/hr-kg or more.
18. The method according to claim 16, wherein the aqueous solution
contains the guest compound at a concentration of from 10 to 26 wt.
%.
19. The method according to claim 16, wherein the aqueous solution
is cooled to a temperature range of from 5.degree. C. to 8.degree.
C.
20. The method according to claim 16, wherein the guest compound is
one selected from the group consisting of a tetra-n-butylammonium
salt, a tetra-iso-amylammonium salt, a tetra-iso-butylphosphonium
salt, or a tri-iso-amylsulfonium salt.
21. A method for producing a hydrate slurry comprising the steps
of: (a) preparing an aqueous solution containing a guest compound
by cooling, to generate at least one selected from the group
consisting of a primary hydrate and a secondary hydrate, wherein
the primary hydrate has smaller hydration number and smaller heat
capacity than the secondary hydrate, the secondary hydrate has
larger hydration number and larger heat capacity than the primary
hydrate,and, (b) cooling the aqueous solution and contacting
nucleus particles as nucleus of the hydrate particles with the
aqueous solution to produce the hydrate particles consisting of the
primary hydrate and the secondary hydrate.
22. The method according to claim 21, wherein the nucleus particles
comprise hydrate particles.
23. The method according to claim 21, wherein the nucleus particles
comprise fine particles.
24. The method according to claim 21, wherein the nucleus particles
have a diameter size of 300 .mu.m or less.
25. The method according to claim 21, wherein the nucleus particles
have a diameter size of 100 .mu.m or less.
26. The method according to claim 21, wherein the nucleus particles
have a diameter size of 10 .mu.m or less.
27. The method according to claim 21, wherein the nucleus particles
have a diameter size of 10 .mu.m or less and the nucleus particles
in the aqueous solution have a concentration of 0.1 mg/l or
more.
28. The method according to claim 21, wherein the nucleus particles
comprise fine particles having heavier specific gravity than the
specific gravity of the aqueous solution, and wherein the step of
contacting the nucleus particles with the aqueous solution
comprises dispersing and floating the nucleus particles in the
aqueous solution.
29. The method according to claim 21, wherein the step of
contacting the nucleus particles with the aqueous solution
comprises dispersing and floating the nucleus particles
precipitated in the aqueous solution.
30. The method according to claim 21, wherein the specific gravity
of the nucleus particles is almost equal with the specific gravity
of the aqueous solution, and the nucleus particles are dispersed
and floated in the aqueous solution.
31. The method according to claim 21, wherein the step of
contacting the nucleus particles with the aqueous solution
comprises the step of agitating the aqueous solution containing the
nucleus particles.
32. The method according to claim 21, wherein the step of
contacting the nucleus particles with the aqueous solution
comprises the step of contacting the aqueous solution with members
to which surface the nucleus particles adhere.
33. An apparatus for producing hydrate slurry by cooling an aqueous
solution containing a guest compound and by generating hydrate
particles comprising: a generation heat exchanger having a heat
transfer surface for cooling the aqueous solution and cooling the
aqueous solution by contacting the aqueous solution with the heat
transfer surface; and, a nucleus particles supply mechanism for
supplying the nucleus particles as nuclei of the hydrate particles
to the aqueous solution passing through the generation heat
exchanger.
34. The apparatus according to claim 33, wherein the nucleus
particles supply mechanism comprises a supply mechanism for
supplying the hydrate particles.
35. The apparatus according to claim 33, wherein the nucleus
particles supply mechanism comprises a hydrate particle generation
mechanism capable of operation independent from the generation heat
exchanger.
36. The apparatus according to claim 33, wherein the nucleus
particles supply mechanism comprises a storage tank holding a part
of the hydrate slurry produced in the generation heat
exchanger.
37. The apparatus according to claim 33, wherein the nucleus
particles supply mechanism comprises a nucleus particle recovery
mechanism for recovering the nucleus particles precipitated in the
aqueous solution and for supplying the recovered nucleus particles
to the generation heat exchanger.
38. An apparatus for producing a hydrate slurry by cooling an
aqueous solution containing a guest compound, to generate a primary
hydrate and a secondary hydrate, wherein the primary hydrate has
smaller hydration number and smaller heat capacity than the
secondary hydrate, the secondary hydrate has larger hydration
number and larger heat capacity than the primary hydrate by
generating hydrate particles, comprising: a generation heat
exchanger having a heat transfer surface for cooling the aqueous
solution and cooling the aqueous solution by the contacting the
aqueous solution with the heat transfer surface; and, at least one
part of a surface of members, wherein the surface contacts with the
aqueous solution in the generation heat exchanger, and wherein
nucleus particles as nuclei of the hydrate particles adhere to the
surface.
39. The apparatus according to claim 38, wherein the generation
heat exchanger comprises: a cylindrical heat transfer surface, a
separation blade member rotating, simultaneously with contacting
and sliding on the heat transfer surface for separating the hydrate
generated on the heat transfer surface, and, a surface of the
separation blade member having a surface adhered by the nucleus
particles.
40. An apparatus for producing a hydrate slurry by cooling an
aqueous solution containing a guest compound and by generating
hydrate particles, comprising: a generation heat exchanger having a
heat transfer surface for cooling the aqueous solution and cooling
the aqueous solution by contacting the aqueous solution with the
heat transfer surface; and, an agitation mechanism for dispersing
and floating the nucleus particles as nuclei of the hydrate
particles in the aqueous solution.
41. A Hydrate thermal storage medium comprising: an aqueous
solution filled in the hermetically sealed container, to generate
at least one selected from the group consisting of a primary
hydrate and a secondary hydrate, wherein the primary hydrate has
smaller hydration number and smaller heat capacity than the
secondary hydrate, the secondary hydrate has larger hydration
number and larger heat capacity than the primary hydrate.
42. The thermal storage medium according to claim 41, wherein the
aqueous solution contains the guest compound, the concentration
being from 10% to 26%.
43. The thermal storage medium according to claim 41, wherein the
guest compound contained in the aqueous solution is one selected
from the group consisting of a tetra-n-butylammonium salt, a
tetra-iso-amylammonium salt, a tetra-iso-butylphosphonium salt, and
a tri-iso-amylsulfonium salt.
44. A hydrate cold thermal storage transporting medium comprising:
a primary hydrate and a secondary hydrate, wherein the primary
hydrate has smaller hydration number and smaller heat capacity than
the secondary hydrate, the secondary hydrate has larger hydration
number and larger heat capacity than the primary hydrate.
45. The hydrate cold thermal storage transporting medium according
to claim 44, wherein the aqueous solution contains the guest
compound, the concentration being from 10% to 26%.
46. The hydrate cold thermal storage transporting medium according
to claim 44, wherein the guest compound contained in the aqueous
solution is one selected from the group consisting of a
tetra-n-butylammonium salt, a tetra-iso-amylammonium salt, a
tetra-iso-butylphosphonium salt, and a tri-iso-amylsulfonium
salt.
47. The hydrate thermal storage medium according to claim 13,
wherein the contained corrosion inhibitor is at least one selected
from the group consisting of sodium nitrite, sodium sulfite, sodium
pyrophosphate, and benzotriazole.
48. The method according to claim 16, the aqueous solution is
cooled to generation temperature or less of the secondary hydrate.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an apparatus for storing
heat utilizing latent heat of hydrate, specifically to a thermal
storage medium, which contains large number of thermal storage body
immersed in a cooling medium liquid such as water. And, each
cooling medium body contains, in hermetic state, a hydrate or an
aqueous solution that generates hydrate slurry as the latent heat
generating material. Furthermore, the present invention relates to
a thermal storage medium suitable for the thermal storage system
such as air conditioners and the like, and relates to a method for
producing the thermal storage medium.
BACKGROUND OF THE INVENTION
[0002] Conventionally, for increasing the thermal storage capacity
of a water tank for storing heat using the sensible heat of water,
there is a related art of immersing large number of thermal storage
body in the water in the tank. That type of related art has an
advantage of increasing the thermal storage capacity utilizing
existing water tank being used to store heat.
[0003] An examples of the above-described thermal storage body is a
hermetically sealed container containing a thermal storage medium
which solidifies at or above the water-solidification temperature,
that's to say, 0.degree. C. or above, such as various kinds of wax.
In the process, thermal storage medium is solidified before water
solidifies, thus utilizing the latent heat of the thermal storage
medium to increase the thermal storage capacity.
[0004] However, that type of cooling medium body has a drawback. In
the above-mentioned process, when the thermal storage medium in the
cooling medium body solidifies, no fluidization of the thermal
storage medium occurs, inside the thermal storage medium body.
Furthermore, because of the low thermal conductivity of the
solidified thermal storage medium, the efficiency of heat exchange
reduces, between the water in the water tank and the thermal
storage medium.
[0005] To prevent the drawback, there is a countermeasure to
decrease the size of container, which has the cooling medium body,
and to increase the surface area relative to the volume. The
method, however, needs to charge a vast number of thermal storage
bodies into the water tank. Thus, in case of using a large-sized
water tank, a vast number of thermal storage bodies are
required.
[0006] In the above-described water tank or the like for storing
heat, the temperature of internal thermal storage medium, or water,
varies with various conditions. For example, the thermal storage
temperature is necessary to be changed depending on the kind of
refrigerating machine that cools the water in the water tank, or
depending on the usage of the thermal load side that utilizes the
water of the water tank as the thermal storage tank.
[0007] Accordingly, the conventional thermal storage medium such as
one kind of wax is not suitable for attaining thermal storage
temperature in various kinds of usage because of fixed
solidification temperature thereof. As a result, the thermal
storage temperature of the above-described water in the water tank
has the restricted range.
[0008] Furthermore, from the viewpoint of the thermal storage
medium of the related art as a thermal storage apparatus, various
kinds of apparatus for thermal storage medium are used in
air-conditioners and the like. The thermal storage medium are used
to store discontinuously supplied energy such as midnight power and
waste heat generated in plants, thus to effectively use energy by
utilizing thus stored cold heat at air-conditioners.
[0009] The apparatus, which uses ice, is known as one of the
thermal storage medium apparatus in the world. In the apparatus,
which makes use of the ice, the ice is produced during midnight
time by utilizing midnight power and the like, and the cold thermal
stored heat is utilized at air-conditioners during daytime.
Compared with the apparatus by thermal storage medium, which
utilizes sensible heat of water, the ice-used thermal storage
medium has an advantage of capable of storing a large amount of the
cold thermal capacity owing to the latent heat of the ice. In order
to produce the ice, however, water requires to be cooled to a
further low temperature than the solidification temperature
thereof. On the contrary, the solidification temperature of the
water is low. Therefore, the coefficient of performance of the
refrigerating machine degrades. In addition, the ice and the ice
slurry are difficult in handling and transporting, so the apparatus
becomes complex and large.
[0010] From another point of view, there is a thermal storage
medium body made of gas hydrate, which is disclosed in, for
example, JP-A-2-203138, (the term "JP-A" referred herein signifies
the "unexamined Japanese patent publication"). The technology
disclosed in the patent publication, however, uses
chlorofluorocarbon-base refrigerant R11 as the coolant for
generating gas hydrate. The R11 is a compound having large ozone
depletion potential, and exists as gas phase under atmospheric
pressure, thus a hermetically sealed container requires, which
raises a problem to needs the expensive apparatus using the thermal
storage medium.
SUMMARY OF THE INVENTION
[0011] The present invention was completed on the basis of the
above-described background. An object of the present invention is
to provide a thermal storage medium for storing heat by immersing a
cooling medium body in a cooling medium liquid such as water,
wherein a hydrate is used as the thermal storage medium in the
cooling medium body to improve the efficiency of heat exchange with
the cooling medium liquid, and to provide a thermal storage medium
that can adjust the thermal storage temperature of the cooling
medium liquid responding to individual uses, and that prevents
supercool of aqueous solution, which generates the hydrate.
[0012] Furthermore, the inventors of the present invention carried
out the studies to present a hydrate-base thermal storage medium
that can be generated at higher temperatures than the temperature
of ice, (hereinafter "a solid-liquid mixed phase hydrate slurry
consisting of hydrate, hydrate particles, and aqueous solution" is
referred to simply as "a hydrate-base thermal storage medium"), and
focused on hydrates of tetra-n-butylammonium bromide and the like.
The hydrate of tetra-n-butylammonium bromide obtained by cooling an
aqueous solution of tetra-n-butylammonium bromide can readily be
prepared in a form of hydrate or hydrate slurry by cooling the
aqueous solution using commonly available cooling water, brine, or
the like. The hydrate of tetra-n-butylammonium bromide has a large
amount of heat capacity. The present invention provides a method
for efficiently producing the hydrate-base thermal storage
medium.
[0013] Thus, the present invention discloses the following.
[0014] Firstly, a thermal storage apparatus for using a hydrate
thermal storage medium comprising: a storage tank for storing a
cooling medium liquid; a refrigerating machine, connected with the
storage tank via a pipe for cooling the cooling medium liquid, the
cooling medium liquid circulating between the storage tank and the
refrigerating machine; a thermal storage body immersed in the
cooling medium liquid, wherein the thermal storage medium
comprising, a hermetically sealed container, an aqueous solution to
generate a hydrate, being filled in the hermetically sealed
container to generate a hydrate, fine particles to prevent the
aqueous solution from super-cooling, the fine particles being
contained in the hermetically sealed container.
[0015] Secondly, a hydrate thermal storage medium comprising: an
aqueous solution containing a guest compound; wherein the aqueous
solution comprising, a slurry of a thermal storage medium
containing the hydrate of the guest compound, a corrosion inhibitor
of at least one compound selected from the group consisting of
sodium nitrite, sodium sulfite, sodium pyrophosphate, and
benzotriazole.
[0016] Thirdly, a method for producing a hydrate thermal storage
medium comprising the steps of: (a) preparing an aqueous solution
containing a guest compound; and, (b) cooling the aqueous solution
to produce a hydrate slurry.
[0017] Fourthly, a method for producing a hydrate slurry comprising
the steps of: (a) preparing an aqueous solution containing a guest
compound; and, (a) cooling the aqueous solution and contacting
nucleus particles as nuclei of the hydrate particles with the
aqueous solution to produce the hydrate particles.
[0018] Fifthly, an apparatus for producing hydrate slurry by
cooling an aqueous solution containing a guest compound and by
generating hydrate particles comprising: a generation heat
exchanger having a heat transfer surface for cooling the aqueous
solution and cooling the aqueous solution by contacting the aqueous
solution with the heat transfer surface; and, a nucleus particles
supply mechanism for supplying the nucleus particles as nuclei of
the hydrate particles to the aqueous solution passing through the
generation heat exchanger.
[0019] Sixly, an apparatus for producing a hydrate slurry by
cooling an aqueous solution containing a guest compound and by
generating hydrate particles, comprising: a generation heat
exchanger having a heat transfer surface for cooling the aqueous
solution and cooling the aqueous solution by contacting the aqueous
solution with the heat transfer surface; and, an agitation
mechanism for dispersing and floating the nucleus particles as
nuclei of the hydrate particles in the aqueous solution.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows a schematic drawing of a thermal storage medium
of the First Embodiment of the Best Mode A according to the present
invention.
[0021] FIG. 2 shows a perspective view of a cooling medium body of
the First Embodiment of the Best Mode A according to the present
invention.
[0022] FIG. 3 shows a cross sectional view of a cooling medium body
of the Second Embodiment of the Best Mode A according to the
present invention.
[0023] FIG. 4 shows a cross sectional view of a cooling medium body
of the Third Embodiment of the Best Mode A according to the present
invention.
[0024] FIG. 5 shows a cross sectional view of a cooling medium body
of the Fourth Embodiment of the Best Mode A according to the
present invention.
[0025] FIG. 6 shows a perspective view of a cooling medium body of
the Fifth Embodiment of the Best Mode A according to the present
invention.
[0026] FIG. 7 shows a perspective view of a cooling medium body of
the Sixth Embodiment of the Best Mode A according to the present
invention.
[0027] FIG. 8 shows a cross sectional view of a cooling medium body
and a drive mechanism thereof of the Seventh Embodiment of the Best
Mode A according to the present invention.
[0028] FIG. 9 shows a schematic drawing of a thermal storage medium
of the Eighth Embodiment of the Best Mode A according to the
present invention.
[0029] FIG. 10 shows a schematic drawing of a thermal storage
medium of the Ninth Embodiment of the Best Mode A according to the
present invention.
[0030] FIG. 11 shows a perspective view of a cooling medium body of
the Tenth Embodiment of the Best Mode A according to the present
invention.
[0031] FIG. 12 shows a cross sectional view of a thermal storage
medium of the Tenth Embodiment of the Best Mode A according to the
present invention.
[0032] FIG. 13 shows a schematic drawing of a thermal storage
medium of the Eleventh Embodiment of the Best Mode A according to
the present invention.
[0033] FIG. 14 is a graph showing the state of generation of TBAB
hydrate, as a function of concentration and temperature of TBAB
aqueous solution, of the Best Embodiment B according to the present
invention.
[0034] FIG. 15 is a block diagram showing an example of thermal
storage system using a thermal storage medium of the Best Mode B
according to the present invention.
[0035] FIG. 16 is a graph showing the effect of corrosion
prevention of various kinds of corrosion inhibitors in Experimental
Example 1 of the Best Mode B according to the present
invention.
[0036] FIG. 17 is a graph showing the effect of corrosion
prevention of sodium nitrite and sodium sulfite on carbon steel
samples in the Experimental Example 2 of the Best Mode B according
to the present invention.
[0037] FIG. 18 is a graph showing the effect of corrosion
prevention of sodium nitrite and sodium sulfite on copper samples
in the Experimental Example 2 of the Best Mode B according to the
present invention.
[0038] FIG. 19 is a graph showing the relation between the heat
capacity of hydrate and the temperature of hydrate slurry, on
generating the first hydrate and the second hydrate by cooling a
TBAB aqueous solution containing 20 wt. % of TBAB, of the Best Mode
C according to the present invention.
[0039] FIG. 20 is a graph showing the process of generation of TBAB
hydrate slurry by cooling aqueous solution of 17 wt. % TBAB of the
Best Mode C according to the present invention.
[0040] FIG. 21 is a block diagram of an example of the thermal
storage system applying the method of the Embodiment of the Best
Mode C according to the present invention.
[0041] FIG. 22 is a graph showing the result of the Experimental
Example of the present invention of the Best Embodiment C according
to the present invention.
[0042] FIG. 23 is a graph showing the result of the Experimental
Example of a comparative example of the Best Mode C according to
the present invention.
[0043] FIG. 24 shows a schematic drawing of the First Embodiment of
the hydrate thermal storage medium of the Best Mode D according to
the present invention.
[0044] FIG. 25 shows a schematic drawing of the Second Embodiment
of the hydrate thermal storage medium of the Best Mode D according
to the present invention.
[0045] FIG. 26 shows a schematic drawing of the Third Embodiment of
the hydrate thermal storage medium of the Best Mode D according to
the present invention.
[0046] FIG. 27 shows a schematic drawing of the hydrate slurry
producing apparatus giving a Embodiment of the Best Mode E
according to the present invention.
[0047] FIG. 28 shows a schematic drawing of the apparatus of a
Embodiment of the Best Mode F according to the present
invention.
[0048] FIG. 29 shows a longitudinal part cross sectional view of
the generation heat exchanger of a Embodiment of the Best Mode F
according to the present invention.
[0049] FIG. 30 shows a cross sectional view of a separation blade
member viewed along 603-603 line of FIG. 29 of the Best Embodiment
F according to the present invention.
[0050] FIG. 31 is a diagram of the result of an experiment
conducted to confirm the effect of the Best Mode F according to the
present invention.
[0051] FIG. 32 is another diagram of the result of an experiment
conducted to confirm the effect of the Best Embodiment F according
to the present invention.
[0052] FIG. 33 is further diagram of the result of an experiment
conducted to confirm the effect of the Best Mode F according to the
present invention.
[0053] FIG. 34 is still another diagram of the result of an
experiment conducted to confirm the effect of the Best Embodiment F
according to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0054] Best Mode A
[0055] The Best Mode A for carrying out the present invention is
described below referring to the drawings. The Best Mode A uses an
aqueous solution of a thermal storage medium, or a guest compound,
sealed in a container of cooling medium body. An example of the
guest compound is tetra-n-butylammonium bromide (hereinafter
referred to as TBAB).
[0056] The aqueous solution of TBAB varies the temperature of
generating the hydrate thereof depending on the concentration of
TBAB. That is, increased concentration of TBAB increases the
temperature of generating the hydrate, and decreased concentration
of TBAB decreases the temperature of hydrate generation.
Accordingly, if the concentration of TBAB in the aqueous solution
is adjusted to a low level, and if the temperature of hydrate
generation, or the thermal storage temperature, is adjusted to a
low level, the stored heat can be used as thermal storage tank for
cooling service or the like. If the concentration of TBAB in the
aqueous solution is determined to increase the hydrate generating
temperature to a high level, the stored heat can also be used as
hot for heating snow-melting roads, snow-melting roofs,
temperature-conditioned warehouses for preventing freezing in the
cold district.
[0057] The above-described TBAB aqueous solution may generate
hydrate particles at around 12.degree. C., for example, to create a
hydrate slurry. The aqueous solution may, however, induce
supercooling. If the supercooling occurs, the hydrate particles
cannot be generated, unless the aqueous solution is cooled to below
the above-given temperature of 12.degree. C., which degrades the
efficiency of refrigerating machine. If the supercool state is
vanished, the generated hydrate may adhere to the wall surface of
the container, or the generated hydrate particles may agglomerate
to each other to degrade the fluidity of the hydrate slurry.
[0058] Applicable guest compounds other than TBAB given above
include tetra-iso-amylammonium salt, tetra-iso-butylphosphonium
salt, and tri-iso-amylsulfonium salt.
[0059] FIG. 1 and FIG. 2 show the First Embodiment of the Best Mode
A. The First Embodiment adopts a tank 1, which contains a cooling
medium liquid such as water 2. The First Embodiment also applies a
refrigerating machine 3. The water 2 in the tank 1 circulates
between the tank 2 and the refrigerating machine 3 via pipes 4, 5.
Thus, the water 2 is cooled to store cold heat.
[0060] The water 2 in the tank 1 also circulates between the tank 1
and cold heat load-side (not shown) such as air conditioner via
pipes 6, 7, to utilize the stored cold heat . The water 2 in the
tank 1 has a large number of thermal storage body 30 immersed
therein, thus increasing the heat capacity of the water 2 in the
tank 1. The configuration of this thermal storage body 30 is
described later.
[0061] There is a circulation mechanism 10 in the tank 1 as a
container drive means that changes the position of the thermal
storage body 30 or moves the thermal storage body 30. The
circulation mechanism 10 contains a pump 11, a nozzle 12, and other
components to circulate the water 2 in the tank 1 to flow or
agitate thereof.
[0062] There is an air-injection mechanism 20 at the bottom of the
tank 1 to change the position of the thermal storage body 30 or
move the thermal storage body 30. The air-injection mechanism 20
contains a high-pressure air source 21, a valve 22, a nozzle 23,
and other components to inject air from the bottom of the tank 1
into the water 2, thus agitating the water 2 in the tank 1 by
ascending air bubbles.
[0063] The configuration of the cooling medium body 30 is described
below referring to FIG. 2. The cooling medium body 30 is provided
with a spherical hermetically sealed container 31. The container 31
contains an aqueous solution 32 containing TBAB.
[0064] In addition, a specified quantity of air or other gas is
sealed in the container 31 to bring the apparent specific gravity
of the whole cooling medium body 30 to equal with the specific
gravity of surrounding cooling medium liquid, for example, water.
Consequently, the heart reservoir 30 can freely float in the
water.
[0065] Instead of forming a space in the container 31 by sealing a
gas, a shrinkable ball or cylindrical gas capsule containing sealed
gas therein may be put into the container 31 of the cooling medium
body 30 to adjust the total specific gravity of the cooling medium
body 30. Furthermore, the generation of hydrate can be enhanced by
adhering fine particles to the inner surface of the gas
capsule.
[0066] The above-described space or gas capsule is able to
compensate the volume changes caused by expansion and shrink of the
aqueous solution 32 in the container 31 of the cooling medium body
30 or by generation of hydrate, through the expansion and shrink of
the space or gas capsule.
[0067] Furthermore, fine particles 33 are sealed in the container
31 to prevent supercool of the above-described aqueous solution. An
example of the fine particles 33 is granulated slag particles
having a particle size to allow them float in the aqueous solution.
The fine particles 33 have sedimenting property to sediment during
a long time of stationary state. When the hydrate particles, which
were generated using the fine particles 33 as the nuclei in the
container 31, are melted in the container 31, and when the
generation and melting of the hydrate particles are repeated, the
fine particles 33 tend to deposit on the inner surface of the
container 31.
[0068] According to the First Embodiment, a pair of blade members
34 is attached to outside of the spherical container 31 extending
outward therefrom. Each of these blade members 34 is attached at
different angle relative to the outer surface of the container 31
to each other. Consequently, when the surrounding water flows, the
drag or lift generated on these blade members 34 makes the
container 31 rotate centering on, for example, X axis.
[0069] The function of the apparatus of the First Embodiment is
described below. The refrigerating machine 3 is operated by, for
example, midnight surplus power, to store the produced cold heat to
the water 2 in the tank 1.
[0070] If the water 2 in the tank 1 is cooled, the internal aqueous
solution 32 is cooled via the wall of the container 31 of the
cooling medium body 30 to generate hydrate particles, thus creating
hydrate slurry. When the water 2 in the tank 1 is used as the
thermal storage tank, inversely from the above-described process,
the hydrate slurry in the cooling medium body 30 melts.
Accordingly, the latent heat of the hydrate increases the thermal
storage capacity of the cooling medium body 30.
[0071] Since the above-described hydrate slurry is fluidable, the
efficiency of heat exchange with surrounding water is high. In
addition, since the fine particles 33 exist in the aqueous solution
32 in the container 31, the generation of hydrate particles is
enhanced using these fine particles 33 as the nuclei, thus
preventing supercool of the aqueous solution.
[0072] As described above, since the fine particles 33 tend to
sediment in the container 31 or adhere to inner surface of the
container 31, the quantity of the fine particles dispersed and
floated in the aqueous solution 32 reduces to degrade the
above-described effect of preventing supercooling. Nevertheless, as
described above, the water 2 in the tank 1 is circulated to flow by
the circulation mechanism 10, and is agitated by ascending air
bubbles created by the air injected from the air-injection
mechanism 20. As a result, also the thermal storage body 30 varies
their positions and moves their locations under the flow and
agitation of the water 2. Thus, the aqueous solution 32 in the
container 31 of the cooling medium body 30 is agitated to keep the
fine particles 33 disperse and float in the aqueous solution 32.
Consequently, the effect of preventing supercooling is
sustained.
[0073] To enhance the dispersion and floating of the fine particles
33 by the position change and move of the container 31 of the
cooling medium body 30, it is effective to place plurality of
stirrer chips in the container 31. Alternatively, by attaching
protrusions to the plumbing stirrer chips or setting fibers on the
plumbing stirrer chips, the agitation can further be enhanced.
[0074] The dispersion and floating of the fine particles 33 can
also be enhanced by applying supersonic waves and vibrations to the
water 2 in the tank 1, and by transmitting the supersonic waves and
vibrations to the aqueous solution 32 in the cooling medium body
30. Instead of the supersonic waves and vibrations, magnetic field,
electric field, or the like may be applied for enhancing the
dispersion and floating of the fine particles 33 in the aqueous
solution 32.
[0075] Furthermore, treating or coating of anti-adhesives against
the fine particles applied to the inner surface of the container 31
is also effective. Examples of the coating are that of fluororesin
and of silicone resin.
[0076] The Best Mode A is not specifically limited to the First
Embodiment. For example, FIG. 3 shows the Second Embodiment of the
cooling medium body 30 in the Best Mode A. That is, the container
31 is formed in a cylindrical shape, and is allowed to freely
rotate around the center axis 36. From the peripheral surface of
the container 31, plurality of blade members 35 is protruded in
radial directions. Water flow or ascending bubbles collides against
the blade members 35 to rotate the container 31.
[0077] The Second Embodiment has the same configuration with the
First Embodiment except for the above-given description, and the
same component with that in the First Embodiment shown in FIG. 3
has the same reference number with that in the First Embodiment,
and no further description is given here.
[0078] FIG. 4 shows the Third Embodiment of the cooling medium body
30 in the Best Mode A. The cooling medium body 30 has blade members
37, corresponding to the blade members of the Second Embodiment, at
a tilted angle against the peripheral surface of the container 31.
Owing to the tilt angle of the blade members 37, the cooling medium
body 30 of the Third Embodiment can be rotated by water flow in
only one direction.
[0079] The Third Embodiment has the same configuration with the
First Embodiment except for the above-given description, and the
same component with that in the First Embodiment shown in FIG. 4
has the same reference number with that in the First Embodiment,
and no further description is given here.
[0080] FIG. 5 shows the Fourth Embodiment of the cooling medium
body 30 in the Best Mode A. The cooling medium body 30 has
plurality of pocket-shape concavities 38 on outer periphery of the
container 31. Air bubbles are caught by a concavity 38 to rotate
the cooling medium body 30. When the concavity 38 that holds the
bubbles faces up, the captured bubbles are released from the
concavity 38. By repeating the capture and release of bubbles, the
cooling medium body 30 keeps rotating.
[0081] The Fourth Embodiment has the same configuration with the
Second Embodiment except for the above-given description, and the
same component with that in the Second Embodiment shown in FIG. 5
has the same reference number with that in the Second Embodiment,
and no further description is given here.
[0082] FIG. 6 shows the Fifth Embodiment of the cooling medium body
30 in the Best Mode A. The container 31 is formed in a cylindrical
shape. From the peripheral surface of the container 31, plurality
of blade members 39 is protruded at a tilt angle against the axial
direction of the container 31. The cooling medium body 30 of the
Fifth Embodiment can rotate around the center axis 36 even by a
water flow along the axis indicated by the arrow A direction in the
figure.
[0083] The Fifth Embodiment has the same configuration with the
Second Embodiment except for the above-given description, and the
same component with that in the Second Embodiment shown in FIG. 6
has the same reference number with that in the Second Embodiment,
and no further description is given here.
[0084] FIG. 7 shows the Sixth Embodiment of the cooling medium body
30 in the Best Mode A. Plurality of blade members 40, each of which
is continuous along the axial direction of the cylindrical
container 31, are attached to the periphery of the container 31 in
tilted angles both against the peripheral direction and against the
axial direction. The cooling medium body 30 of the Sixth Embodiment
can rotate around the center axis 36 even by a water flow along the
axis indicated by the arrow A direction in the figure.
[0085] The Sixth Embodiment has the same configuration with the
Third Embodiment except for the above-given description, and the
same component with that in the Third Embodiment shown in FIG. 7
has the same reference number with that in the Third Embodiment,
and no further description is given here.
[0086] FIG. 8 shows the cooling medium body 30 and a drive means
thereof according to the Seventh Embodiment of the cooling medium
body 30 in the Best Mode A. A line 41 such as a string and a chain
is wound around the cylindrical container 31. Ascending and
descending the line 41 rotate the container 31. Inside of the
container 31, a weight 42 to bring the container 31 to original
rotational position is attached. The weight 42 may be fixed or not
fixed to the inside of the container 31. In the case that the
weight is not fixed, the weight functions to further disperse the
fine particles.
[0087] The Seventh Embodiment has the same configuration with the
Third Embodiment except for the above-given description, and the
same component with that in the Third Embodiment shown in FIG. 8
has the same reference number with that in the Third Embodiment,
and no further description is given here.
[0088] FIG. 9 shows the thermal storage medium according to the
Eighth Embodiment in the Best Mode A. The tank 1 is divided to
segments by plurality of nearly vertical partition plates 50. In
each of the divided segments, plurality of cylindrical cooling
medium body elements 30 which are similar with those applied in the
Second Embodiment are placed in free rotational mode. The tank 1 is
provided with a water charge opening 51 and a water discharge
opening 52. An air supply pipe 53 is mounted at the bottom of the
tank 1, and the air supply pipe 53 has many nozzle holes 54.
According to the configuration of the Eighths Embodiment, air is
ejected from the nozzle holes 54 of the air supply pipe 53 to
become ascending bubbles between the partition plates 50, thus
rotating each cooling medium body element 30.
[0089] The Eighth Embodiment has the same configuration with the
First Embodiment except for the above-given description, and the
same component with that in the First Embodiment shown in FIG. 9
has the same reference number with that in the First Embodiment,
and no further description is given here.
[0090] FIG. 10 shows a schematic drawing of the thermal storage
medium according to the Ninth Embodiment in the Best Mode A. The
thermal storage medium is provided with a mechanical drive
mechanism for thermal storage body. That is, the cooling medium
body 30 in the Ninth Embodiment is in cylindrical shape. The
thermal storage body 30 is arranged in a group bound by a flexible
endless running body 60 such as line such as string, or stripe such
as belt and net. The endless running body 60 is driven by a pulley
61 to rotate each cooling medium body 30.
[0091] The Ninth Embodiment has the same configuration with the
First Embodiment except for the above-given description, and the
same component with that in the First Embodiment shown in FIG. 10
has the same reference number with that in the First Embodiment,
and no further description is given here.
[0092] FIG. 11 and FIG. 12 show the aqueous solution stirrer used
in the Tenth Embodiment in the Best Mode A. The aqueous solution
stirrer 70 is put into, for example, the cylindrical container of
the cooling medium body, and agitates the aqueous solution in the
container under rotation of the container.
[0093] The aqueous solution stirrer 70 is structured by a pillar
shape body 71 made of metal or other material and a plurality of
stirring members 72 protruded from the body 72 in radial
directions. When the container of the cooling medium body rotates,
the aqueous solution stirrer 70 rolls and rotates in the container
to agitate the aqueous solution. The aqueous solution stirrer
according to the Tenth Embodiment has fine particles attached to
the surface thereof. Accordingly, when the aqueous solution stirrer
70 rolls and rotates to agitate the aqueous solution, the fine
particles on the surface thereof successively contact with the
aqueous solution to prevent supercool of the aqueous solution.
[0094] When the aqueous solution stirrer 70 according to the Tenth
Embodiment is applied, there is no need of sealing fine particles
of powder into the container of the cooling medium body.
Nevertheless, both of the aqueous solution stirrer 70 and the
powder fine particles may be sealed in the container to increase
the effect of prevention of supercool of the aqueous solution.
[0095] FIG. 13 shows the cooling medium body drive mechanism of the
thermal storage medium according to the Eleventh Embodiment in the
Best Mode A. Similar with the Seventh Embodiment shown in FIG. 8,
lines 75 winding around individual cylindrical cooling medium body
30 rotate the plurality of thermal storage body 30 at a time. An
end of each line 75 is attached to the fixed side of the tank 1,
such as a wall of the tank 1, while the other end thereof is wound
around a rotational shaft 76.
[0096] According to the Eleventh Embodiment, when the rotary shaft
76 rotates in one direction and then in counter direction, the
other end of each line 75 moves upward and downward, which makes
each cooling medium body 30 rotate in one direction and then in
counter direction. According to the Eleventh Embodiment, each line
75 hangs each cooling medium body 30. Therefore, there is no need
of special mechanism for supporting each cooling medium body 30 in
free rotational mode because each cooling medium body 30 is hung by
the line 75, thus the structure of the thermal storage medium
becomes simple.
[0097] The Best Mode A is not limited to the above-described
Embodiments. For example, the above-given Embodiments apply a
container drive mechanism. If, however, the water in the tank flows
owing to the heat exchange, as observed in the case of using an
existing water tank for storing heat, or if the container of
cooling medium body naturally changes its position or moves caused
by convection flow or by varied water level, that kind of container
drive mechanism is not specifically necessary.
[0098] Best Mode B
[0099] The detail description of the Best Mode B is given
below.
[0100] According to the Best Mode B, hydrate slurry of
tetra-n-butylammonium bromide, (hereinafter referred to simply as
TBAB), can be prepared by cooling an aqueous solution of TBAB. The
concentration of TBAB aqueous solution is not specifically limited.
Generally, however, an aqueous solution containing 5 to 42 wt. %
TBAB is preferred. The TBAB aqueous solution is cooled preferably
to a temperature range of from 5.degree. C. to 12.degree. C., more
preferably from 5.degree. C. to 80.degree. C., which temperature
range is used in general storage air conditioners.
[0101] The TBAB hydrate slurry prepared by cooling the TBAB aqueous
solution can store and transfer the heat ranging from the stored
heat transport density of water (7 Mcal/m.sup.3 as sensible heat at
a temperature difference of 7.degree. C.) to about 6 times the
density, or to about 42 Mcal/m.sup.3.
[0102] It was found that, when a TBAB aqueous solution is cooled,
primary hydrate having smaller hydration number yields secondary
hydrate having larger hydration number at, for example, about
8.degree. C. or below. FIG. 14 shows the relation between
concentration and temperature of TBAB aqueous solutions, giving a
graph indicating the phase equilibrium between the primary hydrate
slurry and the secondary hydrate slurry, prepared by an experiment
conducted by the inventors of the present invention. As seen in
FIG. 14, when a TBAB aqueous solution is cooled, the primary
hydrate or the secondary hydrate is generated at around 8.degree.
C. or below. The secondary hydrate has larger heat capacity than
that of the primary hydrate at a significance level. That is, when,
for example, a TBAB aqueous solution containing 20 wt. % TBAB is
cooled to generate the primary hydrate and the secondary hydrate,
the primary hydrate has about 14 kcal/kg of heat capacity at
6.degree. C., and the secondary hydrate has about 27 kcal/kg of
heat capacity, which is a significant difference, (or about double
the former value, in this case).
[0103] The hydrate-base thermal storage medium containing TBAB
hydrate slurry according to the Best Mode B contains sodium
nitrite, sodium sulfite, sodium diphosphate, and/or benzotriazole
as the corrosion inhibitor. These kinds of corrosion inhibitor
significantly reduce the corrosion of metallic materials
structuring the circulation system of the hydrate-base thermal
storage medium caused by the TBAB hydrate-base thermal storage
medium, particularly the corrosion of iron-base metallic materials
(including carbon steels and galvanized steels) and of copper-base
metallic materials (including brass). In particular, sodium nitrite
and sodium sulfite show excellent corrosion resistance to both the
iron-base metallic materials and the copper-base metallic
materials.
[0104] The concentration of the corrosion inhibitor in the TBAB
hydrate slurry may be at a level to prevent corrosion. The
concentration of 5,000 wt.ppm is sufficient. In particular, sodium
nitrite and sodium sulfite reduce the corrosion of copper by TBAB
to a level of corrosion by hot water at concentrations of max.
5,000 ppm. Normally, the concentration of corrosion inhibitor is
100 wt.ppm or more.
[0105] FIG. 15 is a block diagram showing an example of thermal
storage system using the thermal storage medium according to the
Best Mode B. The thermal storage system given in FIG. 15 has a
refrigerating machine 111, a heat exchanger 112 for producing TBAB
hydrate, and an storage tank 113. There are a line L101 between the
refrigerating machine 111 and the heat exchanger 112 for charging
the cooled water from the refrigerating machine 111 to the heat
exchanger 112, and a line L102 therebetween for circulating the
heat-exchanged water from the heat exchanger 112 to the
refrigerating machine 111. A water transfer pump P101 is installed
in the line L101.
[0106] A line L103 connects the heat exchanger 112 and the storage
tank 113.
[0107] A line L104 and a circulation pump P102 is installed in the
line L104 connect the storage tank 113 and the heat exchanger
112.
[0108] On operating the thermal storage system, water cooled in the
refrigerating machine 111 to, for example, 4.degree. C. is
circulated to the heat exchanger 112. At the same time, the TBAB
aqueous solution containing the corrosion inhibitor according to
the Best Mode B held in the storage tank 113 is circulated from the
heat exchanger 112 to the storage tank 113 via the line L104 and
the line L103 using the circulation pump P102, (the first
circulation system). The heat-exchanged water is circulated to the
refrigerating machine 111 to be cooled as described above.
[0109] The thermal storage medium according to the Best Mode B is
prepared only by cooling the TBAB aqueous solution containing a
specified amount of corrosion inhibitor to a temperature range of
from about 5.degree. C. to about 8.degree. C. Normally using water
and brine can be utilized as the cooling liquid to obtain the
thermal storage medium. Furthermore, since the thermal storage
medium according to the Best Mode B suppresses the corrosion, the
degree of corrosion of piping is similar with the corrosion by
water.
[0110] The Best Mode B is described below referring to examples.
The Best Mode B is, however, not limited by these examples.
EXPERIMENTAL EXAMPLE 1
[0111] The TBAB was dissolved in water to a concentration of 25-wt.
%. Sodium nitrite, sodium diphosphate, or benzotriazole was added
to thus prepared TBAB aqueous solution by 5,000 wt.ppm. A carbon
steel sample or a copper sample was immersed in the TBAB aqueous
solution at 80.degree. C. for 15 days. Then, the sample was washed
with water and dried, and weighed. Based on the obtained data, the
mass loss of each sample over one year was calculated. The result
is given in FIG. 16. Similar experiment was conducted for the case
of without addition of corrosion inhibitor (or sole TBAB aqueous
solution) and for the case of water instead of TBAB aqueous
solution. The result is also given in FIG. 16. In the figure, X
designates water, Y designates sole TBAB aqueous solution, A
designates TBAB aqueous solution containing sodium nitrite, B
designates TBAB aqueous solution containing sodium diphosphate, and
C decimates TBAB aqueous solution containing benzotriazole.
[0112] The result revealed that sodium nitrite gives excellent
corrosion-preventive effect to both carbon steel and copper, that
sodium diphosphate gives excellent corrosion-preventive effect to
carbon steel, and that benzotriazole gives excellent
corrosion-preventive effect to copper.
EXPERIMENTAL EXAMPLE 2
[0113] The TBAB was dissolved in water to a concentration of 25-wt.
%. Sodium nitrite or sodium sulfite was added to thus prepared TBAB
aqueous solution at various concentration levels. Experiment
similar with the Experimental Example 1 was given to thus prepared
solutions. FIG. 17 shows the result on carbon steel sample, and
FIG. 18 shows the result on copper sample.
[0114] These results show that both sodium nitrite and sodium
sulfite give almost equal excellent corrosion-preventive effect to
both carbon steel and copper, and, particularly to copper, they
reduce the corrosiveness of TBAB aqueous solution to equivalent
level of hot water corrosiveness by adding them by max. 5,000
wt.ppm.
[0115] Best Mode C
[0116] According to the Best Mode C, the aqueous solution
containing tetra-n-butylammonium bromide (hereinafter referred to
simply as TBAB) preferably contains TBAB to a range of from 10 to
26 wt. %. According to the Best Mode C, the aqueous solution
containing TBAB is preferably cooled to a temperature range of from
5.degree. C. to 80.degree. C.
[0117] The Best Mode C is described in detail in the following.
[0118] The secondary hydrate of TBAB has larger heat capacity than
that of the primary hydrate at a significance level. FIG. 19 is a
graph showing the heat capacity of primary hydrate and of secondary
hydrate in relation with the temperatures of slurry of respective
hydrates for the case of generating the primary hydrate and the
secondary hydrate by cooling a 20 wt. % TBAB aqueous solution,
which graph was prepared by the inventors of the present invention.
FIG. 19 shows that the primary hydrate has about 14 kcal/kg of heat
capacity at 6.degree. C., for example, and the secondary hydrate
has about 27 kcal/kg of heat capacity, which is a significant
difference, (or about double the former value, in this case).
[0119] That is, when the TBAB hydrate slurry is used as the thermal
storage medium, efficient generation of the secondary hydrate is
advantageous.
[0120] Although the secondary hydrate is generated when the TBAB
aqueous solution is cooled to 8.degree. C. or below, the primary
hydrate continues the generation even when the TBAB aqueous
solution becomes 8.degree. C. or below, which is a supercool
phenomenon of the primary hydrate. FIG. 20 is a graph showing the
process of generation of TBAB hydrate slurry when the 17 wt. % TBAB
aqueous solution is cooled, which graph was prepared by the
inventors of the present invention. As seen in FIG. 20, when the
TBAB aqueous solution is cooled from around 12.degree. C., the
super-cool of the TBAB aqueous solution vanishes after about 25
minutes to generate the primary hydrate slurry. After about 100
minutes when the primary hydrate slurry is further cooled to about
3.degree. C., the supercool of the primary hydrate vanishes to
generate the secondary hydrate. On transferring from the generation
of primary hydrate slurry to the generation of secondary hydrate
slurry, if the degree of supercool of the primary hydrate slurry is
excessive, the temperature for cooling the TBAB aqueous solution is
required to set to a low temperature level, which reduces the
coefficient of performance of the refrigerating machine. To
compensate the reducing coefficient of performance, the heat
transfer area has to be increased, which leads to increase in the
size of heat exchanger and to increase in cost. Therefore, it is
advantageous to minimize the degree of supercool of the primary
hydrate and to efficiently generate the secondary hydrate.
[0121] During the course of cooling the TBAB aqueous solution, the
inventors of the present invention found that the efficient
generation of the secondary hydrate is attained by cooling the TBAB
aqueous solution in the initial stage of forming the TBAB hydrate
slurry at cooling rates of 6 kcal/hr-kg or more.
[0122] According to the Best Mode C, the concentration of TBAB
aqueous solution is particularly preferable in a range of from 10
to 26 wt. % in view of the heat capacity of the thermal storage
medium consisting of the generated hydrate slurry. (For reference,
the heat capacity of the secondary hydrate at 10% TBAB
concentration is 7 kcal/kg at 5.degree. C., and that at 26% TBAB
concentration is 42 kcal/kg at 5.degree. C.)
[0123] With similar viewpoint, the TBAB aqueous solution is
preferably cooled to a range of from 5.degree. C. to 8.degree. C. A
TBAB hydrate slurry prepared by cooling a TBAB aqueous solution
containing 10 to 26 wt. % of TBAB from, for example, 12.degree. C.,
which is within a temperature range of 5.degree. C. to 12.degree.
C. used by general storage air conditioners, to a range of from
5.degree. C. to 8.degree. C. at the above-described cooling rate
can store and transport heat ranging from 14 to 42 Mcal/m.sup.3
corresponding to about 1 to 6 times the stored heat transport
density of water. That is, very large density of heat can be stored
and transferred under the condition of 26-wt. %, secondary hydrate,
and 5.degree. C. Specifically, when the initial concentration of
TBAB aqueous solution is in a range of from 10 to 22 wt. %, and
when the temperature of the secondary hydrate slurry of TBAB is
5.degree. C., the slurry is able to have a heat capacity
corresponding to about four times that of water. When the initial
concentration of TBAB aqueous solution is in a range of from 18 to
26 wt. %, the slurry is able to have a heat capacity corresponding
to four times that of water even when the temperature of secondary
hydrate slurry of TBAB is at 8.degree. C.
[0124] The slurry of thermal storage medium according to the Best
Mode C may contain a compound such as ethylene glycol having lower
solidification temperature than that of water for adjusting
temperature, a corrosion inhibitor such as sodium nitrite and
sodium sulfite for preventing corrosion of piping structuring the
circulation system, and/or a surfactant such as cationic surfactant
(such as stearyl trimethylammonium chloride, cetyl
trimethylammonium chloride) for reducing pressure drop in
piping.
[0125] Cooling of TBAB aqueous solution according to the Best Mode
C may be given at the cooling rate to the TBAB aqueous solution
from the beginning of the cooling, or may be given from the initial
stage that generates the primary hydrate.
[0126] FIG. 21 is a block diagram showing an example of thermal
storage system according to the Best Mode C. The thermal storage
system given in FIG. 21 has a refrigerating machine 211, a heat
exchanger 212 for producing TBAB hydrate slurry, and a storage tank
213. There are a line L201 between the refrigerating machine 211
and the heat exchanger 212 for charging the brine cooled by the
refrigerating machine 211 to the heat exchanger 212, and a line
L202 therebetween for circulating the heat-exchanged brine from the
heat exchanger 212 to the refrigerating machine 211. A brine
transfer pump P201 is installed in the line L201.
[0127] A line L203 connects the heat exchanger 212 and the storage
tank 213. A hydrate identifier 214 is located in the line L203, and
a valve V201 is positioned at downstream side of the hydrate
identifier 214.
[0128] A line L204 connects the storage tank 213 and the heat
exchanger 212. A valve V202 is located in the line L204, and a
circulation pump P202 is positioned at downstream side of the valve
V202.
[0129] On the line L203, a branch line L205 is given between the
identifier 214 and the valve V201. The branch line L205 is
connected with the line L204 between the valve V202 and the
circulation pump P202. A valve V203 is located in the line
L205.
[0130] On operating the thermal storage system, brine cooled in the
refrigerating machine 211 to, for example, 2.degree. C. is
circulated to the heat exchanger 212. At the same time, the TBAB
aqueous solution AS held in the storage tank 213 is circulated from
the heat exchanger 212, the identifier 214, and to the storage tank
213 via the line L204 and the line L203 using the circulation pump
P202, (the first circulation system). During the circulation of the
TBAB aqueous solution, the identifier 214 identifies the generation
state of the hydrate slurry. The heat-exchanged brine is circulated
to the refrigerating machine 211 to be cooled as described
above.
[0131] If the generated hydrate in the slurry is identified as the
primary hydrate, a command generated from the identifier 214 orders
the valve V201 to close and the valve V203 to open. Thus, the route
of the primary hydrate slurry to the storage tank 213 is shut, and
the primary hydrate slurry is circulated to the heat exchanger 212
and the identifier 214 via the line L204, the line L203, and the
line L205, respectively, (the second circulation system). When the
circulation system is changed as described above, the quantity of
the TBAB aqueous solution (slurry) in the second circulation system
becomes less than that in the first circulation system, so the
cooling rate per unit mass in the heat exchanger 212 is
increased.
[0132] When the generation of secondary hydrate is detected by the
identifier 214, a command generated from the identifier 214 orders
the valve V201 and the valve V202 to open, and orders the valve
V203 to close, thus changing the circulation system of the hydrate
slurry from the second circulation system to the first circulation
system. As a result, the secondary hydrate exists in the second
circulation system. During the process to generate the secondary
hydrate in the heat exchanger 212, the secondary hydrate is rapidly
generated, and the TBAB hydrate slurry is stored in the storage
tank 213. Thus stored TBAB can be used during daytime in, for
example, air conditioners.
[0133] The identifier 214 is provided with, for example, an
instrument that determines a physical property, which differs
between the primary hydrate and the secondary hydrate. When the
physical property determined by the instrument exceeds a specified
threshold value, or when the generation of secondary hydrate is
detected, the above-described command is generated. For example,
since the density of the primary hydrate is about
1.08.times.10.sup.3 kg/m.sup.3, and the density of the secondary
hydrate is about 1.03.times.10.sup.3 kg/m.sup.3, the
above-described instrument may be a densitometer. Also, since the
solid content of the primary hydrate slurry is significantly
smaller than that of the secondary hydrate slurry, each of the
hydrates differs in the viscosity significantly to each other, so
the instrument may be a viscometer. An electrolytic conductivity
detector, an electrostatic capacity meter, an electric resistance
meter, or the like may do the method for identification.
[0134] The cooling rate may be regulated by the circulation rate of
the TBAB aqueous solution using the pump P202.
[0135] According to the Best Mode C, since the supercool phenomenon
of the primary hydrate is not generated as described before, the
coefficient of performance of the refrigerating machine increases,
and the temperature difference between the cooling water (brine)
for cooling the TBAB aqueous solution and the generated hydrate
slurry can be maintained at a large value. Therefore, the heat
transfer area of the heat exchanger can be reduced, and the compact
design and the cost reduction of the heat exchanger can be
attained. Furthermore, according to the Best Mode C, the TBAB
aqueous solution is necessarily cooled only to temperature level
ranging from about 5.degree. C. to about 8.degree. C., so commonly
using water or brine can be used by cooling as the cooling liquid
for generating the hydrate slurry. In addition, the Best Mode C can
be applied in a temperature range of from 5.degree. C. to
12.degree. C., which is a range of commonly used by the cooling
storage air conditioning system.
[0136] The Best Mode C is described below referring to example. The
Best Mode C is, however, not limited by these examples.
EXPERIMENTAL EXAMPLE
[0137] A TBAB aqueous solution of 20 wt. % TBAB was cooled at rates
of 6 kcal/hr-kg or more, and the temperatures of generated hydrate
slurry were determined with the cooling time, also the exchanged
heats (kcal/hr-kg) per 1 kg of generated hydrate slurry were
determined with time. The result is shown in FIG. 22.
[0138] As a comparative example, similar TBAB aqueous solution was
cooed at a rate of 2 kcal/hr-kg to give similar measurement as
above. The result is shown in FIG. 23.
[0139] As seen in FIG. 22, when the TBAB aqueous solution was
cooled at rates of 6 kcal/hr-kg or more, the primary hydrate was
generated after about 30 minutes, and after that, with the cooling
rate of 6 kcal/hr-kg or more, the temperature of the hydrate slurry
kept to around 80.degree. C. for about 120 minutes. During the
constant temperature period, the generation of primary hydrate
changed to the generation of secondary hydrate. That is, when the
TBAB aqueous solution is cooled at rates of 6 kcal/hr-kg or more,
the secondary hydrate slurry can be produced during the initial
stage of generating hydrate slurry. After completely changed to the
secondary hydrate slurry, the temperature of the secondary slurry
begins to reduce.
[0140] To the contrary, as shown in FIG. 23, when the cooling rate
after generated the primary hydrate slurry was 2 kcal/hr-kg,
supercool phenomenon of the primary hydrate slurry distinctively
appeared up to about 80 minutes, and, after that, the supercool
phenomenon of the primary hydrate slurry vanished to enter the
process of generating secondary hydrate, then the behavior of the
solution followed similar pattern with that in FIG. 22.
[0141] Best Mode D
[0142] On preparing hydrate slurry, to prevent supercooling, it is
effective to disperse and float nucleus particles in the aqueous
solution, which nucleus particles function as the nuclei of the
hydrate particles. The fine particles as nuclei are particularly
effective when they have 10 .mu.m or smaller size. Those fine
particles are easily dispersed and floated in aqueous solution so
that they become nuclei of hydrate particles and that they have
very strong effect of preventing supercooling.
[0143] If the concentration of the fine particles having 10 .mu.m
or smaller size is 0.1 mg/l or more, they sufficiently contact with
aqueous solution and they are effective to prevent supercooling.
Since normal drinking water has Grade 1 of turbidity, and
industrial water has around Grade 20 of turbidity, (1 mg-kaolin/l
is defined as Grade 1 of turbidity), these drinking water and
industrial water contain 0.1 mg/l or more of fine particles. The
supercool can be prevented by using drinking water or industrial
water as the water for aqueous solution containing guest compound.
If the fine particles having 10 .mu.m or smaller size are used as
the nucleus particles, the upper limit of the concentration thereof
in the aqueous solution is around 100 mg/l. If the fine particles
exceeding the upper limit are dispersed and floated in the aqueous
solution, the heat transfer performance of the heat exchanger
degrades, which is not preferable.
[0144] When the fine particles as the nucleus fine particles have
100 .mu.m or smaller size, the effect to prevent supercooling is
enhanced by agitating the aqueous solution to disperse and float
the fine particles therein. Adequate range of the concentration of
fine particles in aqueous solution is from 1 mg/l to 5 g/l. If the
concentration exceeds the upper limit, drift or stagnant zone
likely appears in the apparatus for generating hydrate slurry,
which is not favorable. If the concentration is less than the lower
limit, the effect to prevent supercooling becomes weak.
[0145] The Best Mode D is described below while describing the
apparatus and the functions of the apparatus of the Best Mode D
referring to the drawings. FIG. 24 shows a schematic drawing of the
First Embodiment of the hydrate thermal storage medium according to
the Best Mode D. The apparatus according to the Best Mode D
generates hydrate and stores heat by cooling an aqueous solution
containing a guest compound such as TBAB.
[0146] A tank 301 is for storing heat, and has, for example,
cylindrical shape giving a reverse-cone shape at a bottom section
wall 302 thereof. For example, an aqueous solution 303 of TBAB
described above is held in the tank 301.
[0147] A refrigerating machine 304 produces low temperature coolant
using, for example, electricity or waste heat, and supplies the low
temperature coolant to a cold heat load-side (not shown) such as
air-conditioner via a supply pipe 305, further recovers the coolant
via a return pipe 306, thus circulates the coolant between the
refrigerating machine 304 and the cold heat load-side.
[0148] A generation heat exchanger 307 is located in the tank 301
to generate hydrate by cooling the aqueous solution. The low
temperature coolant is supplied and circulated from the
refrigerating machine 304 to the generation heat exchanger 307 to
cool the aqueous solution 303 to generate the hydrate particles.
The hydrate slurry containing thus generated hydrate particles is
held in the tank 301 to stored heat.
[0149] According to the Best Mode D, the refrigerating machine 304
is operated by midnight surplus power or the like to produce low
temperature coolant, which coolant passes through the generation
heat exchanger 307 to cool the aqueous solution in the tank 301 to
produce the hydrate slurry and stored heat. During the period of
large consumption of cold heat in daytime, the stored cold heat is
recovered using the generation heat exchanger 307, and is used as a
part or whole of the cold heat being supplied to the cold heat
load-side, thus achieving the effective usage of energy
resources.
[0150] The method for preventing supercooling in the case that the
aqueous solution in the tank 301 is cooled to generate hydrate is
described below while describing the apparatus and function
thereof. As described above, fine particles are mixed into the
aqueous solution 303, in advance. It is preferable that the fine
particles have the same specific gravity with that of water or have
very small size, 10 .mu.m or less, from the viewpoint to maintain
the state of dispersing and floating over the whole area of the
aqueous solution 303. Nevertheless, while repeating the generation
and melting of hydrate, the fine particles tend to sediment at the
bottom of the tank, as described before, and tend to decrease the
quantity of dispersed and floated fine particles.
[0151] To this point, the Best Mode D adopts granulated slag
particles as the fine particles. The granulated slag particles are
inexpensive and give large effect of preventing super-cooling. The
granulated slag has larger specific gravity than that of TBAB
aqueous solution, and they have a precipitating characteristic. The
Best Mode D, however, selects the granulated slag particles having
slow sedimenting speed within a range of not degrading the
performance of preventing super-cooling, or, for example, those
having around several millimeters a minute of the sedimenting
speed.
[0152] The tank 301 is provided with an aqueous solution
circulation mechanism 310. A pump 311, a valve 312 structures the
aqueous solution circulation mechanism 310, and an ejection nozzle
313 positioned at bottom side wall of the tank 301, and other
components. The aqueous solution is sucked from upper section of
the tank 301 and is ejected from the ejection nozzle 313.
[0153] The aqueous solution ejected from the ejection nozzle 313
circulates in the tank 301. The circulation flow of the aqueous
solution is analyzed in advance, and designed to establish the
conditions that the flow speed of the aqueous solution exceeds the
sedimenting speed of the fine particles even at the zone of lowest
flow speed of the aqueous solution, for example, at corners of the
tank 301, thus dispersing again the fine particles transferred to
the bottom section of the tank 301 to prevent occurrence of
precipitation of fine particles at the bottom of the tank 301.
[0154] Consequently, owing to the circulation flow of aqueous
solution in the tank 301, the fine particles are kept in their
dispersed and floated state over the whole area of the aqueous
solution, and the quantity of fine particles floating in the
aqueous solution does not decrease, thus assuring effective
preventing super-cooling. According to the apparatus and the
method, for maintaining the fine particles in dispersed and floated
state, only the aqueous solution component of the hydrate slurry
may be circulated at a relatively low speed, which consumes less
power, or energy, thus avoiding the degradation of energy serving
effect which is an object of the thermal storage medium.
[0155] As described above, the fine particles are kept in their
floating state owing to the circulation flow in the tank 301.
Therefore, above-described granulated slag particles, which have
large effect of preventing super-cooling, can be applied as the
fine particles in spite of their sedimenting property, and there is
no specific limitation on the material and particle size of the
fine particles.
[0156] The above-described Best Mode D deals with the case of
circulation of aqueous solution inside the tank 301. Actual flow
pattern in the tank 301 is, however, complex, and the circulation
flow may give irregular flow patterns, or what is called the
"agitation".
[0157] According to the Best Mode D, adding to the above-given
mechanism, plurality of mechanisms for enhancing the dispersion and
floating of fine particles is adopted. One of these kinds of
mechanisms is a bottom section circulation mechanism 320 mounted to
the tank 301.
[0158] A pump 321, a valve 322, structures the bottom section
circulation mechanism 320, an ejection nozzle 323 located at upper
side wall of the tank 301, and other components. The aqueous
solution is sucked from the bottom center of the bottom wall
section 302, or the lowermost part, of the tank 301, and is ejected
into the aqueous solution in the tank 301 from the ejection nozzle
323 to distribute the solution.
[0159] As described before, since the fine particles tend to
sediment at the bottom section of the tank 301, the aqueous
solution at bottom section thereof contains large quantity of fine
particles. By sucking the aqueous solution of the bottom section to
disperse into the aqueous solution at upper section thereof, the
fine particles are effectively dispersed and floated in the aqueous
solution.
[0160] A temperature detection mechanism 330 is located at bottom
section of the tank 301. The temperature detection mechanism 330
detects the temperatures of aqueous solution to determine the
generation of super-cool in the aqueous solution in the tank 301. A
controller (not shown) processes the signals generated from the
temperature detection mechanism 330. Only when the super-cool
appeared, the controller actuates the bottom section circulation
mechanism 320.
[0161] As described above, supercool appears when the quantity of
fine particles floating in the aqueous solution decreases, or when
large quantity of fine particles sediment at the bottom of the tank
301. Therefore, only in that case, the bottom section circulation
mechanism 320 is actuated to let the aqueous solution containing
large quantity of fine particles disperse in the aqueous solution
to further effectively disperse and float the fine particles in the
aqueous solution. Accordingly, the bottom section circulation
mechanism 320 does not necessarily operate all the time, thus
further reducing the power consumption.
[0162] To a part of the aqueous solution circulation mechanism 310
and the bottom section circulation mechanism 320, additional
mechanism to add fresh fine particles or to add an aqueous solution
containing fresh fine particles may be applied. The mechanism for
adding fresh fine particles may be applied other than to the
aqueous solution circulation mechanism 310 and the bottom section
circulation mechanism 320.
[0163] As another mechanism for dispersing and floating fine
particles, a supersonic wave oscillation mechanism 340 is applied
to the tank 301. The supersonic wave oscillation mechanism 340
applies supersonic waves to the aqueous solution in the tank 301 to
let the fine particles disperse and float in the aqueous
solution.
[0164] Different from the above-described mechanisms, the
supersonic wave oscillation mechanism does not need to circulate,
or move, the fine particles along with the aqueous solution, thus
the energy necessary to sustain the fine particles in dispersed and
floated state is substantially only the energy to move solely the
fine particles or to prevent the precipitation of fine particles,
which means less energy consumption. Although the efficiency of the
supersonic wave oscillation mechanism 340 is naturally taken into
account, the mechanism consumes theoretically least amount of
energy.
[0165] As a separate mechanism for dispersing and floating the fine
particles, a vibration mechanism 350 is applied to the tank 301.
The vibration mechanism 350 vibrates the bottom wall section 302 of
the tank 301 to make the sediment fine particles disperse and float
in the aqueous solution. Also the vibration mechanism 350 consumes
theoretically small energy for dispersing and floating the fine
particles, similar with the supersonic wave oscillation mechanism
340.
[0166] An air-injection mechanism 360 is applied to the tank 301 as
a mechanism for dispersing and floating the fine particles in
aqueous solution. The air-injection mechanism 360 is structured by
a high pressure air supply mechanism 361, a valve 362, an ejection
nozzle 363 attached to the bottom section of the tank 301, and
other components.
[0167] The air-injection mechanism 360 supplies air from the bottom
section of the tank 301 into the aqueous solution. By thus
generated ascending air bubbles through the aqueous solution, the
aqueous solution or hydrate slurry is agitated, and the fine
particles are dispersed and floated. Since the mechanism also makes
the aqueous solution surrounding the generation heat exchanger 307
flow owing to the ascending bubbles, the efficiency of the heat
transfer also increases. The reference numbers 380, 381 designate
three-way valves, and 390, 391 designate pumps.
[0168] The apparatus of the Best Mode D is not limited to the one
applied in the First Embodiment. FIG. 25 shows a schematic drawing
of the Second Embodiment apparatus according to the Best Mode D.
The Second Embodiment is applied under a condition that a cold heat
load-side, which is able to receive hydrate slurry containing fine
particles, is available. In that case, the hydrate slurry in the
tank 301 is directly supplied and circulated via a supply pipe 371
and a return pipe 372.
[0169] The apparatus according to the Second Embodiment has similar
configuration with that of the First Embodiment, and the same
component with those in the First Embodiment shown in FIG. 25 has
the same reference number with that in the First Embodiment, and no
further description is given here.
[0170] FIG. 26 shows a schematic drawing of the Third Embodiment
apparatus according to the Best Mode D. Separate from the
generation heat exchanger 307, a supply heat exchanger 380 is
located in the tank 301. The supply heat exchanger 308 conducts
heat exchange between the hydrate slurry in the tank 301 and the
coolant. The coolant is supplied to and is circulated from the cold
heat load-side using a pump 381 via a supply pipe 382 and a return
pipe 383.
[0171] The apparatus according to the Third Embodiment has similar
configuration with that of the apparatus of the First Embodiment
except for the above-given description, and the same component with
that in the First Embodiment shown in FIG. 25 has the same
reference number with that in the First Embodiment, and no further
description is given here.
[0172] The Best Mode D is not limited to the above-described
Embodiments. For example, above-described Embodiments have various
types of mechanisms for keeping the fine particles disperse and
float in the aqueous solution. They are, however, not necessarily
applied all of them, and only arbitrary one may be used.
[0173] According to the above-described Embodiments, the
temperature detection mechanism detects supercool, and the bottom
section circulation mechanism is operated only when the super-cool
appeared. The bottom section circulation mechanism, however, may be
operated always or may be operated over an intermittent period.
Also for other mechanisms to disperse and float the fine particles,
they may be operated only when the temperature detection mechanism
detects supercool.
[0174] Best Mode E
[0175] FIG. 27 shows the configuration of a hydrate slurry
producing apparatus according to the Best Mode E. The reference
number 401 designates an storage tank holding an aqueous solution
in which a hydration agent (for example, tetra-n-butylammonium
bromide) is dissolved, the reference number 405 designates a
refrigerating machine for cooling a cold water as the coolant, the
reference numbers 420, 430 designate plate-type heat exchangers for
conducting the heat exchange between the aqueous solution and the
cold water. An advantage of a plate-type heat exchanger is high
heat transfer performance with less compact area, because a large
amount of the heat transfer area per one unit volume is available
and because the heat transfer is achieved by the countercurrent
mode with the narrow gap of the plate. The reference number 409
designates a hot water tank holding hot water for heating, where
the hot water tank 409 contains a heating system.
[0176] The aqueous solution in the storage tank 401 circulates the
route of a pump 404, a pipeline 402 (supply line), the plate-type
heat exchangers 420, 430, and a pipeline 403 (return line). The
cold water for cooling the aqueous solution circulates the route of
the refrigerating machine 405, a pump 408, a pipeline 406 (supply
line), the plate-type heat exchangers 420, 430, and a pipeline 407
(return line). The hot water in the hot water tank 409 circulates
the route of a pump 412, a pipeline 410 (supply line), a pipeline
406, the plate-type heat exchangers 420, 430, a pipeline 407, and a
pipeline 411 (return line).
[0177] At respective inlets and outlets for the cold water located
at respective heat exchangers 420, 430, cutoff valves 423, 424,
433, 434 to shut the channel of the respective pipelines are
attached. Furthermore, branch pipelines are located between
respective cold water cutoff valves and heat exchangers. The branch
pipelines are connected with respective hot water pipelines 410,
411 for heating via respective hot water cutoff valves 425, 426,
435, 436 to shut the flow of respective branch pipelines. The
respective inlets and outlets of the aqueous solution pipelines of
respective heat exchangers 420, 430 are provided with respective
aqueous solution cutoff valves 421, 422, 431, 432 to shut the
channel of the respective aqueous solution pipelines.
[0178] At respective inlets and outlets of cold water on the
respective heat exchangers 420, 430, thermometers 428, 429, 438,
439 are mounted to determine the temperatures of cold water. At
respective inlets of the cold water on respective heat exchangers
420, 430, flow meters 427, 437 are mounted to determine the flow
rate of cold water. At respective inlets and outlets of the aqueous
solution on respective heat exchangers 420, 430, thermometers 441,
442, 443, 444 are mounted to determine the temperatures of the
aqueous solution.
[0179] At respective inlets of the aqueous solution on respective
heat exchangers 420, 430, flow meters 451, 452 are mounted to
determine the flow rate of the aqueous solution. Differential
pressure gages 453, 454 are mounted between the inlets and the
outlets of the aqueous solution at respective heat exchangers 420,
430, to determine the pressure difference of the aqueous
solution.
[0180] A processing and controlling section 413 is applied to
acquire the observed data from the thermometers 428, 429, 438, 439,
441, 442, 443, 444, from the flow meters 427, 437, 451, 452, and
from the differential pressure gauges 453, 454, and to calculate
the amount of exchanged heat (=temperature difference .times.flow
rate.times.specific heat), thus controlling the respective cutoff
valves responding to the obtained temperature, amount of exchanged
heat, or flow rate and pressure difference of the aqueous
solution.
[0181] The method for producing hydrate slurry using the apparatus
is described below.
[0182] The aqueous solution in the storage tank 401 is pumped by
the generation pump 404 to pass through the pipeline 402, the
plate-type heat exchangers 420, 430, then to return to the storage
tank 401 via the pipeline 403. The cold water cooled by the
refrigerating machine 405 is pumped by the pump 408 to pass through
the pipeline 406 and the plate-type heat exchangers 420, 430, then
to return to the refrigerating machine 405 via the pipeline 407. In
the course of the circulation, the aqueous solution is cooled by
the cold water in the plate-type heat exchangers 420, 430, across
the respective plate-type cooling surfaces, thus producing hydrate
slurry.
[0183] Three units of heat exchangers are prepared, and two of them
are operated, leaving one as stand-by unit. When the pressure drop
increases, one of the operating units is switched to the stand-by
unit to continue the operation of heat exchange. Even four or five
units are operating, one unit is spared as stand-by unit. For
example, in case those two units of plate-type heat exchangers are
operated, initially almost equal flow rate is applied to each of
the heat exchangers 420, 430. Using thermometers 428, 429, 438,
439, and flow meters 427, 437 for determining cold water flow rate,
mounted at inlet and outlet of respective heat exchangers, the
processing and controlling section 413 calculates the quantity of
exchanged heat (=temperature difference.times.flow
rate.times.specific heat).
[0184] Also the aqueous solution flows initially at almost equal
rate through each of the heat exchangers 420, 430. During the
progress of cooling, hydrate slurry is generated in the heat
exchangers, and the hydrate adheres to the cooling surface of the
plates, (for reference, the adhered quantity differs between the
heat exchangers), which becomes the thermal resistance to decrease
the quantity of exchanged heat. When the hydrate adheres to the
cooling surface of plates, the adhered hydrate becomes the
resistance to flow to vary the flow rate, and results in the
increase of pressure difference of aqueous solution between the
inlet and the outlet of aqueous solution on heat exchanger.
[0185] From this point of view, for example, when the quantity of
exchanged heat at the heat exchanger 420 becomes below a
preliminarily specified level, or when the flow rate and the
pressure difference determined by the flow meter 451 and pressure
difference gauge 453, respectively, exceed a preliminarily
specified flow rate and pressure difference, the aqueous solution
cutoff valves 421, 422 are closed, the cold water cutoff valves
423, 424 are closed, the hot water cutoff valves 425, 426 are
opened, further the hot water pump 412 is actuated to let the hot
water in the hot water tank 409 pass through the cold water passage
in the heat exchanger 420, thus conducting the operation for
melting hydrate to melt the hydrate adhered to the cooling surface
of plates. The hot water referred herein may be at 12.degree. C. or
higher temperature. Accordingly, hot water can use outlet hot water
and drain water of absorption refrigerating machine, cooling water
of a cooling tower, on return water of an air-conditioner.
[0186] After a specified period of hydrate melting operation or
after the observed temperature of outlet of cold water passage of
the heat exchanger 420 turned to rise, the open/close of the
above-described cutoff valves are switched again to conduct the
cooling operation of aqueous solution to generate hydrate slurry.
During the operation, total flow of the aqueous solution is not
stopped.
[0187] For another heat exchanger 430, similar operation with that
for the heat exchanger 420 is given.
[0188] That melting operation is given successively to attain
stable production of hydrate slurry.
[0189] If fine particles (such as granulated slag particles) are
adhered to the cooling surface of plates at aqueous solution side
in advance, the degree of supercool (temperature becoming below the
solidification point of hydrate) can be minimized to assure stable
production of hydrate slurry.
[0190] Conventionally, plates of plate heat exchanger are made of
stainless steel, copper, titanium, and the like. They are, however,
in as-formed state of base material, without giving surface
treatment, so the generated hydrate adheres to the plate surface,
and once adhered hydrate is not easily separated. To this point,
description on effective means to prevent adherence of hydrate
slurry onto the plate surface of plate-type heat exchanger is given
below.
[0191] The first means is to apply coating on the surface of
cooling side of plate, or aqueous solution side, to reduce friction
factor thereof. The coating includes electroplating such as hard
chromium coating, nickel coating, iron coating, alloy coating,
electroless nickel coating using phosphorus, boron, or the like,
dispersion coating such as electrocrystallization coating and
electroless nickel coating, and lubricating alloy coating.
[0192] The second means is to apply coating, painting, or polishing
to the surface of plate-type at the side of the hydrate slurry flow
to reduce friction factor and surface roughness. The coating
includes that of fluororesin, silicone resin, and inorganic
resin.
[0193] By processing the surface of the plate-type at the side of
the hydrate slurry flow, as in the case of the first means and the
second means, the hydrate slurry becomes difficult to adhere to the
plate-type surface, thus allowing stable production of hydrate
slurry.
[0194] In the production of hydrate slurry, hydrate is generated on
the cooling surface of plate-type of the heat exchanger during the
process of cooling the aqueous solution. When the cooling further
proceeds, the percentage of hydrate in the hydrate slurry increases
to increase the viscosity of the aqueous solution. As a result, the
turbulence of the flow of aqueous solution in the heat exchanger is
suppressed, which makes it difficult to separate hydrate from the
cooling surface of the plate.
[0195] On the contrary, the output of the aqueous solution
circulation pump 404 is increased at a certain interval to increase
the flow speed of hydrate slurry in the aqueous solution flow
passage in the plate-type heat exchangers 420, 430. Consequently,
the enhanced flow promotes the separation of hydrate adhered to the
cooling surface of plate, thus allowing stable production of
hydrate slurry. The interval of intermittent operations may be
arbitrarily determined.
[0196] Also when the pump for circulating the aqueous solution is
controlled at a fixed flow rate by using an inverter or the like,
the hydrate, which is adhered on the cooling surface of the plates
of heat exchangers 420, 430, increases the pressure drop across the
heat exchangers. In this case, the rotational speed of the pump is
increased, depending on the automatically rising of the output or
discharge pressure of the pump. Consequently, the fluid force
increases to enhance the hydrate, which is attached to the cooling
surface of the plates, to separate. In the end, the method makes it
possible to produce the hydrate slurry at a constant level.
[0197] Best Mode F
[0198] In case of producing hydrate slurry, it is effective to
disperse and float nucleus particles, which become hydrate
particles in the aqueous solution, in order to prevent
supercooling. The fine particles as nuclei are particularly
effective when they have a diameter size of 10 .mu.m or less. Those
fine particles are easily dispersed and floated in aqueous solution
so that they become nuclei of hydrate particles and that they have
very strong effect of preventing super-cooling. If the
concentration of the fine particles having a diameter size of 10
.mu.m or less is 0.1 mg/l or more, the nucleus particles
sufficiently get in contact with the aqueous solution. And the
contact is effective for preventing supercooling. Normal drinking
water has Grade 1 of turbidity, and industrial water has around
Grade 20 of turbidity, (1 mg-kaolin/l is defined as Grade 1 of
turbidity). So, these drinking water and industrial water contain
0.1 mg/l or more of fine particles as a concentration. Therefore,
the usage of drinking water or industrial water as the water for
aqueous solution containing guest compound can prevent the
super-cooling. If the fine particles having a diameter size of 10
.mu.m or less are used as the nucleus particles, the upper limit of
the concentration thereof in the aqueous solution is around 100
mg/l. If the fine particles, which exceed the upper limit, are
dispersed and floated in the aqueous solution, the heat transfer
performance of the heat exchanger degrades, which does not invite a
preferable result.
[0199] In case that the fine particles as the nucleus fine
particles have diameter size of 100 .mu.m or less, agitating the
aqueous solution brings the aqueous solution the effectiveness for
preventing super-cooling, by enhancing to disperse and to float the
fine particles in the aqueous solution. Jet flow in the aqueous
solution or agitating by rotary blades is applied for the agitating
means. Adequate range of the concentration of fine particles in the
aqueous solution is from 1 mg/l to 5 g/l. If the concentration
exceeds the upper limit, drift or stagnant zone likely appears in
the apparatus for generating hydrate slurry, which is not
preferable. If the concentration is less than the lower limit, the
effectiveness for preventing super-cooling reduces to a lower
degree.
[0200] In case that the fine particles as the nucleus fine
particles have diameter size of 300 .mu.m or less, super-cooling is
prevented by adhering the nucleus particles to the surface of the
inner wall of the hydrate slurry generating apparatus, or by
adhering the nucleus particles to the surface of the blade of the
agitator or the like, which contact with the aqueous solution in
advance. The concentration of the adhered nucleus particles is 1
g/l or more, to the total concentration value of the aqueous
solution. The adhered surface may cover the whole surface area that
contacts with the aqueous solution.
[0201] Dispersing and floating fine particles, which have heavier
specific gravity than the specific gravity of the aqueous solution,
may also prevent the super-cooling. Since the nucleus particles
precipitate in the aqueous solution, they fully contact with the
aqueous solution to readily become the nuclei of hydrate particles.
Stable production of hydrate slurry is assured by designing the
apparatus and by setting the operational conditions to optimize the
time of precipitation of fine particles in the aqueous solution and
the time of generation of the hydrate slurry in the hydrate
generation apparatus.
[0202] The above-described methods for preventing super-cooling to
contact various kinds of nucleus particles with the aqueous
solution, which generates the hydrate particles, give prospective
effect, even when one of these methods is solely applied to.
Applying two or more of these methods also attains prospective
effect, simultaneously.
[0203] The method according to the Best Mode F and an Embodiment of
apparatus for carrying out the Best Mode F are described below
referring to the drawings. Cooling an aqueous solution containing
tetra-n-butylammonium bromide (TBAB) as the guest compound produces
the hydrate slurry. In this Embodiment, plurality of mechanisms
having characteristics of the Best Mode F are applied, and
plurality of Embodiments for carrying out the Best Mode F for
convenience of understanding. Nevertheless, actual apparatus and
method are not requested to apply all of these pluralities of
mechanisms and of Embodiments.
[0204] FIG. 28 includes a generation heat exchanger 501 that cools
the above-described aqueous solution to generate hydrate slurry. As
shown in FIG. 29, a generation heat exchanger 601 (501 in FIG. 28)
is in a cylindrical shape, having a heat transfer surface 610a at
inner peripheral surface thereof. A cooling jacket 608 through
which a coolant flows surrounds the heat transfer surface 610a. The
coolant circulates between the heat cooling jacket 608 and a
refrigerating machine 502 by a pump 503 to cool the internal
aqueous solution across the heat transfer surface 601a, thus
generating the hydrate.
[0205] A rotary shaft 605 (505 in FIG. 28) is positioned at center
of the generation heat exchanger 601, and the rotary shaft 605 is
driven by a drive mechanism 504 at a specified rotational speed.
The rotary shaft 605 is equipped with a spiral separation blade
member 609. The separation blade member 609 rotates with the rotary
shaft 605 in a contact-sliding mode on the heat transfer surface
601a, thus separating the hydrate adhered to the heat transfer
surface 601a to prevent degradation of heat exchange efficiency of
the heat transfer surface 601a, and to disperse the separated
hydrate into the aqueous solution for assuring more homogeneous
hydrate slurry.
[0206] Furthermore, adding to the above-described effect, the
separation blade member 609 keeps the aqueous solution in flowing
state by agitating thereof in the generation heat exchanger 601.
The means to keep the aqueous solution in flowing state is not
limited to the one given above, and it may be arbitrary one if only
the means keeps the aqueous solution in flowing state by preventing
the generation of condition that a laminar flow layer of the
aqueous solution contacting the heat transfer surface 601a is
established to sustain an infinitesimal portion of the laminar flow
layer of the aqueous solution contacting the heat transfer surface
601a.
[0207] As shown in FIG. 30, the surface of the separation blade
member 609 is covered by a surface 710 on which the nucleus
particles are adhered. The nucleus particles adhered surface 710 is
prepared by applying a mixture of fine particles, for example, of
granulated slag particles, prepared by ejecting water against a
blast furnace slag to finely pulverize, mixed with a binder. The
nucleus particles adhered surface 710 is not limited to position on
the surface of the separation blade member 609, and may be located
at any surface where the flowing aqueous solution contact
therewith.
[0208] The description of the mechanism of circulation of the
aqueous solution around the generation heat exchanger 501 (601 in
FIG. 29) is given below. The reference number 511 in the figure
designates an aqueous solution tank to hold the aqueous solution.
The aqueous solution in the aqueous solution tank 511 is supplied
to a charge opening 506 of the generation heat exchanger 501 by a
pump 513 via a supply pipe 515 and a mixer 516.
[0209] The hydrate slurry generated by cooling the aqueous solution
in the generation heat exchanger 501 is discharged from a discharge
opening 507, and is sent to a hydrate slurry tank 522 via a
distributor 521, where the hydrate slurry is stored. Each of the
hydrate slurry tank 522 and the aqueous solution tank 511 has an
agitator 512.
[0210] The hydrate slurry in the hydrate slurry tank 522 is
discharged from the bottom thereof, and is sent to a hydrate
concentration regulator 523. To the hydrate concentration regulator
523, the aqueous solution is supplied from the aqueous solution
tank 511 by a pump 528 via a pipe 529, where the aqueous solution
is mixed with the hydrate slurry at a specified mixing ratio to
regulate the concentration of solid phase of the hydrate slurry.
Then, the hydrate slurry is charged to a loading unit 526 such as
air conditioner via a pipe 525. After utilized in the loading unit
526, the aqueous solution is returned to the aqueous solution tank
511 via a return pipe 527.
[0211] The nucleus particles charge mechanism that is positioned in
the pipeline described above and that prevents supercooling is
described below. The aqueous solution passing through the system
contains a specified quantity of nucleus particles in advance.
Applicable nucleus particles are various kinds of materials, and
the above-described granulated slag particles are preferred because
they are inexpensive, give stable characteristics, and give strong
effect of preventing super-cooling. The granulated slag particles
have heavier specific gravity than that of aqueous solution, thus
they have a sedimenting property.
[0212] A part of the hydrate slurry discharged from the discharge
opening 507 of the generation heat exchanger 501 is supplied to the
mixer 516 by a pump 532 via the distributor 521 and a pipe 531, and
is fed to the charge opening 506 of the generation heat exchanger
501 along with the aqueous solution.
[0213] A part of the hydrate slurry discharged from the bottom of
the hydrate slurry tank 522 is sent to a hydrate particles tank 534
for preventing supercooling via a pipe 533, where they are stored.
The hydrate particle tank 534 is, for example, an insulation tank,
and is able to store the accepted hydrate slurry for a specified
period without inducing melting of the hydrate particles.
[0214] The hydrate slurry in the hydrate particles tank 534 is sent
to the mixer 516 by a pump 535 via a pipe 536, and is fed to the
charge opening 506 of the generation heat exchanger 501 along with
the aqueous solution.
[0215] The apparatus is provided with a hydrate particle generation
mechanism 514. The hydrate particles generation mechanism 514 can
be operated separately from the hydrate production apparatus
containing the generation heat exchanger 501, and is able to
produce hydrate slurry containing small amount of hydrate
particles.
[0216] The hydrate slurry produced by the hydrate particles
generation mechanism 514 is sent to the mixer 516, and is fed to
the charge opening 506 of the generation heat exchanger 501 along
with the aqueous solution.
[0217] The function of the above-described apparatus, and the
method for preventing supercooling according to the Best Mode F are
described below. When the apparatus is operated, the aqueous
solution in the generation heat exchanger 501 (601 in FIG. 29)
contacts with the heat transfer surface 601a, in flowing state, and
is cooled. Even when an infinitesimal portion of the aqueous
solution contacts with the heat transfer surface 601a to become a
super-cooled state, the infinitesimal portion immediately flows
away and contact with nucleus particles adhered surface 610 on the
separation blade member 609. By the contact with the nucleus
particles, or granulated slag particles, on the nucleus particles
adhered surface 610, the super-cooled state of the infinitesimal
portion is vanished to generate the hydrate particles. As a result,
whole of the aqueous solution in the generation heat exchanger 601
(501) does not enter the super-cooled state, and the supercooling
is effectively prevented.
[0218] As described above, the aqueous solution contains nucleus
particles such as granulated slag, and a part of them flows into
the generation heat exchanger 501 (601) along with the aqueous
solution. Accordingly, the nucleus particles contact with the
infinitesimal portions of the aqueous solution in super-cooled
state to vanish the supercool and to generate the hydrate
particles.
[0219] Once the hydrate particles are generated using the nucleus
particles, the nucleus particles are rejected from the generated
hydrate particles. Consequently, the nucleus particles in the
aqueous solution are sent to the hydrate slurry tank 522 along with
the generated hydrate slurry, where they are separated and
precipitated to the bottom of the tank. As a result, during the
operation of the apparatus, the nucleus particles precipitate and
store at the bottom section of the hydrate slurry tank 522, and the
quantity of nucleus particles that are floating in the aqueous
solution decreases.
[0220] To cope with the phenomenon, a part of the discharged
hydrate slurry is fed to the generation heat exchanger 501 using
the pump 532 via the pipe 531 and the mixer 516. Similar with the
above-described nucleus particles, the hydrate particles in the
aqueous solution overcome the super-cooled state and generate the
hydrate particles. Since the generated hydrate particles is the
same kind of hydrate with the targeted hydrate, they are the most
effective nuclei for generating the hydrate, and they give extreme
effect of preventing super-cooling.
[0221] When the apparatus resumes operation after stop-operation,
the above-described hydrate slurry discharged from the generation
heat exchanger 501 cannot be available. In that case, the hydrate
slurry stored in the hydrate particles hold tank 534 is charged to
the supply opening 506 of the generation heat exchanger 501 via the
pipe 536.
[0222] Even when all of the hydrate particles in the hydrate
particles hold tank 534 is melted, the effect of preventing
super-cooling can be obtained by supplying the aqueous solution in
the tank to the generation heat exchanger 501. That is, since the
nucleus particles are precipitated at the bottom of the hydrate
particles hold tanks 522, as described above, the nucleus particles
are recovered in the hydrate particles hold tank 534. Accordingly,
by supplying these nucleus particles to the generation heat
exchanger 501 along with the aqueous solution, the super-cool is
prevented. Therefore, the hydrate particles hold tank 534 and
related pipelines function both of recovering the nucleus particles
and of re-charge mechanism.
[0223] On starting the operation of the apparatus, if the charge of
hydrate slurry from the hydrate particles hold tank 534 is not
available, the hydrate particles generation mechanism 514 may be
operated separately to charge the generated hydrate slurry to the
generation heat exchanger 501 to prevent supercooling.
[0224] As described above, continued operation of the apparatus may
result in precipitation of the nucleus particles onto the bottom of
the hydrate slurry tank 522 to eliminate almost all of the floating
nucleus particles in the aqueous solution, in some cases. On
resuming operation of the apparatus under the condition, very heavy
supercooling may appear. Even in that situation, however, charging
the hydrate particles from the hydrate particles generation
mechanism to the generation heat exchanger 501 in advance
effectively prevents the super-cooling.
[0225] To avoid unnecessary increase in the number of Embodiments
for description, the Embodiments given above adopt plurality of
mechanisms of the apparatus and methods for operating the apparatus
according to the Best Mode F. Nevertheless, all of the described
mechanisms and methods are not necessarily applied at a time, and
an actual apparatus may adopt any one of them or more one of
them.
[0226] The results of experiments carried out to confirm the
effects of individual mechanisms and methods described above are
described below referring to FIGS. 31 through 34. The experiments
were conducted under the condition that a TBAB aqueous solution was
cooled under agitation. The effect in each of above-described
methods was confirmed. That is, the case that granulated slag
particles, as the nucleus particles, having 100 .mu.m or smaller
size were mixed in an aqueous solution to concentrations of 1 mg/l
or more; the case that a member adhered with granulated slag
particles having 300 .mu.m or smaller size was immersed; and the
case that hydrate particles were mixed in an aqueous solution.
[0227] As a reference example, an aqueous solution of TBAB 25-wt. %
was cooled without agitation, and was analyzed by a differential
thermal analyzer to determine the super-cooled state under cooling
the aqueous solution without agitation. The result was that the
aqueous solution was cooled to -16.degree. C. before vanishing the
supercooling state.
[0228] FIG. 31 shows the case that no nucleus particles were mixed
in the aqueous solution. As seen in the figure, supercool of about
-2.degree. C. appeared for both cases of 40% and 19.8% of
concentration of aqueous solution.
[0229] FIG. 32 shows the case that granular particles having 100
.mu.m or smaller size are mixed as the nucleus particles in the
aqueous solution. The figure shows high preventive effect against
supercooling, down to about 4.degree. C. for 40% concentration of
aqueous solution, and to about 6.degree. C. for 19.8% concentration
of aqueous solution.
[0230] FIG. 33 is the case that a glass rod on which granular slag
particles having 300 .mu.m or smaller size are adhered as the
nucleus particles is immersed in the aqueous solution. For 19.8%
concentration of aqueous solution, supercool appeared down to about
1.degree. C., and for 40% concentration, supercool appeared to
about 6.degree. C., which suggests high preventive effect against
supercooling.
[0231] FIG. 34 is the case that hydrate particles are mixed in the
aqueous solution. For reference, the results of using distilled
water and of using drinking water for preparing the aqueous
solution are also given in the figure. As shown in the figure,
extremely high preventive effect to supercooling is attained,
giving supercool to about 7.degree. C. for 19.8% concentration and
10.degree. C. for 40% concentration.
[0232] The Best Mode F is not limited to the above-given
Embodiments. For example, the above-given Embodiments deal with the
case of using a generation heat exchanger of cooling cylinder type
provided with separation blade member. The Best Mode F is not
limited to the case, and, for example, a shell and tube generation
heat exchanger may be applied.
[0233] The nucleus particles used in the Best Mode F are not
limited to those having heavy specific gravity. For example,
nucleus particles having almost equal specific gravity with that of
the aqueous solution may be used. Those nucleus particles flow with
the aqueous solution and do not sediment, so they prevent various
kinds of problems caused by precipitation of the nucleus
particles.
[0234] INDUSTRIAL APPLICABILITY
[0235] As described above, the apparatus according to the Best Mode
provides large thermal storage capacity owing to the latent heat of
hydrate sealed in the container of the cooling medium body. Since
the container contains fine particles, the fine particles act as
the nuclei of the hydrate particles to enhance the generation of
the hydrate particles, thus preventing supercool of the aqueous
solution. Since the aqueous solution in the container of the
cooling medium body is agitated by changing the position of the
container or by other actions, the fine particles stay in dispersed
and floated state in the aqueous solution, without sedimenting,
thus avoiding degradation of the effect to prevent supercooling. As
described above, the effect of the apparatus is strong.
[0236] Furthermore, according to the Best Mode, a TBAB hydrate
slurry-base thermal storage medium that reduces corrosiveness is
presented.
[0237] In addition, according to the Best Mode, a method for
producing a hydrate-base thermal storage medium that can be
generated at higher temperature than the temperature of ice is
provided without using special coolant. In particular, by cooling
the TBAB aqueous solution at a specified cooling rate, the TBAB
secondary hydrate that has excellent heat capacity is efficiently
produced while suppressing the appearance of supercool of the
primary hydrate.
* * * * *