U.S. patent application number 13/990994 was filed with the patent office on 2013-11-28 for solar heat collecting pipe.
The applicant listed for this patent is Shinichirou Kawane, Kenji Nakamura, Masayoshi Sakuma. Invention is credited to Shinichirou Kawane, Kenji Nakamura, Masayoshi Sakuma.
Application Number | 20130312734 13/990994 |
Document ID | / |
Family ID | 46171612 |
Filed Date | 2013-11-28 |
United States Patent
Application |
20130312734 |
Kind Code |
A1 |
Kawane; Shinichirou ; et
al. |
November 28, 2013 |
SOLAR HEAT COLLECTING PIPE
Abstract
[Problem] To present a solar heat collecting pipe capable of
enhancing the heat collecting efficiency by suppressing the
dissipation of energy transmitted to the heat medium passing
through the inside of an inner pipe. [Solving Means] In the solar
heat collecting pipe 1 including the inner pipe 11 for receiving
sunlight collected by the light collecting mechanism 2, and
transmitting energy to the heat medium 14 passing through the
inside, and the outer pipe 12 covering the outer circumference of
the inner pipe 11, a solar heat absorbing film 11a is applied in a
portion exposed to sunlight of the inner pipe 11 of the solar heat
collecting pipe 1 (the portion exposed to the reflected light of
the sunlight at least on the surface of the inner pipe 11, and a
heat reflecting film 11b is applied in a portion not exposed to
sunlight from the light collecting mechanism 2.
Inventors: |
Kawane; Shinichirou;
(Toshima-ku, JP) ; Nakamura; Kenji; (Toshima-ku,
JP) ; Sakuma; Masayoshi; (Toshima-ku, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kawane; Shinichirou
Nakamura; Kenji
Sakuma; Masayoshi |
Toshima-ku
Toshima-ku
Toshima-ku |
|
JP
JP
JP |
|
|
Family ID: |
46171612 |
Appl. No.: |
13/990994 |
Filed: |
November 9, 2011 |
PCT Filed: |
November 9, 2011 |
PCT NO: |
PCT/JP2011/075790 |
371 Date: |
July 31, 2013 |
Current U.S.
Class: |
126/600 ;
126/657 |
Current CPC
Class: |
F24S 10/45 20180501;
F24S 40/80 20180501; F24S 80/30 20180501; F24S 50/20 20180501; Y02E
10/47 20130101; Y02E 10/44 20130101; F24S 20/20 20180501; F24S
2023/872 20180501; F24S 70/30 20180501; F24S 23/77 20180501; F24S
23/74 20180501; F24S 30/425 20180501; Y02E 10/40 20130101; F24S
70/225 20180501; F24S 70/25 20180501 |
Class at
Publication: |
126/600 ;
126/657 |
International
Class: |
F24J 2/05 20060101
F24J002/05; F24J 2/38 20060101 F24J002/38 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 1, 2010 |
JP |
2010 268553 |
Dec 2, 2010 |
JP |
2010 269191 |
Claims
1. A solar heat collecting pipe comprising an inner pipe for
receiving sunlight collected by a light collecting mechanism, and
transmitting energy to a heat medium passing through the inside,
and an outer pipe covering the outer circumference of the inner
pipe for forming a heat insulating space, wherein a solar heat
absorbing film is applied in a portion exposed to sunlight from the
light collecting mechanism at least on the surface of the inner
pipe, and a heat reflecting film is applied in a portion not
exposed to sunlight from the light collecting mechanism.
2. The solar heat collecting pipe according to claim 1, wherein a
solar heat absorbing film is applied to the entire circumference of
the surface of the inner pipe, and a heat reflecting film is
applied to a portion not exposed to sunlight from the light
collecting mechanism.
3. The solar heat collecting pipe according to claim 1, wherein a
solar heat absorbing film is applied to a portion exposed to
sunlight from the light collecting mechanism of the inner pipe, and
a heat reflecting film is applied to a portion not exposed to
sunlight from the light collecting mechanism.
4. The solar heat collecting pipe according to claim 1, wherein the
solar heat absorbing film is composed of a chrome oxide layer.
5. The solar heat collecting pipe according to claim 1, wherein the
heat reflecting film is composed of an aluminum foil or thin
plate.
6. The solar heat collecting pipe according to claim 1, wherein
mutually adjacent solar heat collecting pipes are coupled together
by forming threads in connection parts of the inner pipes of the
solar heat collecting pips, and connecting in non-expanding state
by connection members having threads formed at both ends, and a
support shaft protruding in the horizontal direction from the
surface of the inner pipe near the coupled position is slidably
inserted into a slit in a horizontal direction formed in a solar
heat collecting pipe support member.
7. The solar heat collecting pipe according to claim 6, wherein the
solar heat collecting pipe support member is formed in a groove
structure having a ventilation space, for shutting out the sunlight
emitted from the light collecting mechanism at an end part of the
outre pipe fixed and inserted into the inner pipe.
8. The solar heat collecting pipe according to claim 7, wherein the
light collecting mechanism is a trough type reflector having a
parabolic section, and the solar heat collecting pipe support
member is affixed to the reflector, and the reflector and the solar
heat collecting pipe are oscillatably mounted on a platform by way
of a common oscillating shaft.
9. The solar heat collecting pipe according to claim 6, wherein the
light collecting mechanism is a trough type reflector having a
parabolic section, and the solar heat collecting pipe support
member is affixed to the reflector, and the reflector and the solar
heat collecting pipe are oscillatably mounted on a platform by way
of a common oscillating shaft.
10. The solar heat collecting pipe according to claim 4, wherein
the heat reflecting film is composed of an aluminum foil or thin
plate.
11. The solar heat collecting pipe according to claim 2, wherein
the solar heat absorbing film is composed of a chrome oxide
layer.
12. The solar heat collecting pipe according to claim 11, wherein
the heat reflecting film is composed of an aluminum foil or thin
plate.
13. The solar heat collecting pipe according to claim 3, wherein
the solar heat absorbing film is composed of a chrome oxide
layer.
14. The solar heat collecting pipe according to claim 13, wherein
the heat reflecting film is composed of an aluminum foil or thin
plate.
15. The solar heat collecting pipe according to claim 2, wherein
mutually adjacent solar heat collecting pipes are coupled together
by forming threads in connection parts of the inner pipes of the
solar heat collecting pips, and connecting in non-expanding state
by connection members having threads formed at both ends, and a
support shaft protruding in the horizontal direction from the
surface of the inner pipe near the coupled position is slidably
inserted into a slit in a horizontal direction formed in a solar
heat collecting pipe support member.
16. The solar heat collecting pipe according to claim 15, wherein
the solar heat collecting pipe support member is formed in a groove
structure having a ventilation space, for shutting out the sunlight
emitted from the light collecting mechanism at an end part of the
outre pipe fixed and inserted into the inner pipe.
17. The solar heat collecting pipe according to claim 15, wherein
the light collecting mechanism is a trough type reflector having a
parabolic section, and the solar heat collecting pipe support
member is affixed to the reflector, and the reflector and the solar
heat collecting pipe are oscillatably mounted on a platform by way
of a common oscillating shaft.
18. The solar heat collecting pipe according to claim 3, wherein
mutually adjacent solar heat collecting pipes are coupled together
by forming threads in connection parts of the inner pipes of the
solar heat collecting pips, and connecting in non-expanding state
by connection members having threads formed at both ends, and a
support shaft protruding in the horizontal direction from the
surface of the inner pipe near the coupled position is slidably
inserted into a slit in a horizontal direction formed in a solar
heat collecting pipe support member.
19. The solar heat collecting pipe according to claim 4, wherein
mutually adjacent solar heat collecting pipes are coupled together
by forming threads in connection parts of the inner pipes of the
solar heat collecting pips, and connecting in non-expanding state
by connection members having threads formed at both ends, and a
support shaft protruding in the horizontal direction from the
surface of the inner pipe near the coupled position is slidably
inserted into a slit in a horizontal direction formed in a solar
heat collecting pipe support member.
20. The solar heat collecting pipe according to claim 5, wherein
mutually adjacent solar heat collecting pipes are coupled together
by forming threads in connection parts of the inner pipes of the
solar heat collecting pips, and connecting in non-expanding state
by connection members having threads formed at both ends, and a
support shaft protruding in the horizontal direction from the
surface of the inner pipe near the coupled position is slidably
inserted into a slit in a horizontal direction formed in a solar
heat collecting pipe support member.
Description
TECHNICAL FIELD
[0001] The present invention relates to a solar heat collecting
pipe, more particularly to a solar heat collecting pipe having an
inner pipe for receiving sunlight collected by a light collecting
mechanism, and transmitting energy to a heat medium passing through
the inside, and an outer pipe covering the outer circumference of
the inner pipe for forming a heat insulating space.
BACKGROUND ART
[0002] Conventionally, a solar heat collecting pipe is proposed,
which has an inner pipe for receiving sunlight collected by a
trough type reflector, and transmitting energy to a heat medium
passing through the inside, and an outer pipe covering the outer
circumference of the inner pipe for forming a heat insulating space
(see, for example, patent document 1).
[0003] Such conventional solar heat collecting pipe includes
various measures for raising the light collecting efficiency of
sunlight, and for example, the solar heat collecting pipe of patent
document 1 proposes to be provided with a structural element for
converging sunlight in the inner tube, in the outer pipe covering
the outer circumference of the inner pipe transmitting energy to
the heat medium passing through the inside, for forming a heat
insulating space.
PRIOR ART LITERATURE
Patent Document
[0004] Patent document 1: Japanese Patent Application Laid-Open No.
2004-239603
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0005] In this manner, the conventional solar heat collecting pipe
is mostly developed with the attention paid to the light collecting
side of sunlight of the light collecting mechanism for enhancing
the heat collecting efficiency, and the inner pipe in which heat
medium passes inside has been proposed only with ideas for
enhancing the heat converging efficiency by forming fine rough
surfaces, or forming a surface reflection preventive layer or
infrared ray reflection layer by coating with extremely special
multiple layers.
[0006] The present invention is devised in the light of the
conventional solar heat collecting pipe, and it is hence a primary
object thereof to present a solar heat collecting pipe enhanced in
heat collecting efficiency by suppressing dissipation of energy
transmitted to the heat medium passing the inside of the inner
pipe.
[0007] It is other object of the present invention to present a
solar heat collecting pipe capable of supporting the solar heat
collecting pipe while absorbing the thermal expansion (linear
expansion) of the inner pipe when connecting adjacent solar heat
collecting pipes.
[0008] It is another object of the present invention to present a
solar heat collecting pipe capable of reducing heat transfer to the
glass-made outer pipe.
Means for Solving the Problems
[0009] To achieve the objects, the solar heat collecting pipe of
the present invention includes an inner pipe for receiving sunlight
collected by a light collecting mechanism, and transmitting energy
to a heat medium passing through the inside, and an outer pipe
covering the outer circumference of the inner pipe for forming a
heat insulating space, in which a solar heat absorbing film is
applied in a portion exposed to sunlight from the light collecting
mechanism at least on the surface of the inner pipe, and a heat
reflecting film is applied in a portion not exposed to sunlight
from the light collecting mechanism.
[0010] In this case, a solar heat absorbing film may be applied to
the entire circumference of the surface of the inner pipe, and a
heat reflecting film may be applied to a portion not exposed to
sunlight from the light collecting mechanism, or a solar heat
absorbing film may be applied to a portion exposed to sunlight from
the light collecting mechanism of the inner pipe, and a heat
reflecting film may be applied to a portion not exposed to sunlight
from the light collecting mechanism.
[0011] The solar heat absorbing film may be composed of a chrome
oxide layer.
[0012] The heat reflecting film may be composed of an aluminum foil
or thin plate.
[0013] Further, mutually adjacent solar heat collecting pipes may
be coupled together by forming threads in connection parts of the
inner pipes of the solar heat collecting pips, and connecting in
non-expanding state by connection members having threads formed at
both ends, and a support shaft protruding in the horizontal
direction from the surface of the inner pipe near the coupled
position may be slidably inserted into a slit in a horizontal
direction formed in a solar heat collecting pipe support
member.
[0014] The solar heat collecting pipe support member may be formed
in a groove structure having a ventilation space, for shutting out
the sunlight emitted from the light collecting mechanism at an end
part of the outre pipe fixed and inserted into the inner pipe.
[0015] The light collecting mechanism may be a trough type
reflector having a parabolic section, and the solar heat collecting
pipe support member may be affixed to the reflector, and the
reflector and the solar heat collecting pipe may be oscillatably
mounted on a platform by way of a common oscillating shaft.
Effects of the Invention
[0016] According to the solar heat collecting pipe of the
invention, a solar heat absorbing film is applied in a portion
exposed to sunlight from the light collecting mechanism at least on
the surface of the inner pipe, and a heat reflecting film is
applied in a portion not exposed to sunlight from the light
collecting mechanism, and therefore dissipation of energy
transmitted to the heat medium may be suppressed, so that the heat
collecting efficiency may be enhanced.
[0017] Still more, the solar heat absorbing film may be composed of
a chrome oxide film, and by a relatively inexpensive structure, it
is effective to strength absorption of energy in the heat medium
passing through the inside of the inner pipe.
[0018] In addition, the heat reflecting film may be composed of an
aluminum foil or thin plate, and by a relatively inexpensive
material, it is effective to suppress dissipation of energy
transmitted to the heat medium passing through the inside of the
inner pipe.
[0019] Further, mutually adjacent solar heat collecting pipes are
coupled together by forming threads in connection parts of the
inner pipes of the solar heat collecting pips, and connecting in
non-expanding state by connection members having threads formed at
both ends, and a support shaft protruding in the horizontal
direction from the surface of the inner pipe near the coupled
position is slidably inserted into a slit in a horizontal direction
formed in a solar heat collecting pipe support member, and
therefore the mutually adjacent solar heat collecting pipes are
coupled easily and firmly by connecting mutually the inner pipes of
the solar heat collecting pipes by screwing in non-expanding state
by the connection members, and the vicinity of the coupled position
can be supported while absorbing the thermal expansion (linear
expansion) of the inner pipe by the solar heat collecting pipe
support member.
[0020] Besides, the solar heat collecting pipe support member may
be built in a groove structure having a ventilation space, capable
of shutting out sunlight emitted from the light collecting
mechanism, at the end part of the outer pipe affixed to the inner
pipe, and therefore heat transfer to the glass-made outer pipe may
be suppressed.
[0021] The light collecting mechanism is a trough type reflector
having a parabolic section, and the solar heat collecting pipe
support member is affixed to the reflector, and the reflector and
the solar heat collecting pipe are oscillatably mounted on a
platform by way of a common oscillating shaft, and therefore the
reflector and the solar heat collecting pipe are composed as an
oscillating body of an integral structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 shows an embodiment of a solar heat collecting device
making use of a solar heat collecting pipe of the present
invention, in which (a) is a front view, and (b) is a side
sectional view.
[0023] FIG. 2 shows a different embodiment of a solar heat
collecting device making use of a solar heat collecting pipe of the
present invention, in which (a) is a front view, (b) is a plan
view, and (c) is a side sectional view.
[0024] FIG. 3 shows an embodiment of a solar heat collecting pipe
of the present invention, in which (a) is a schematic diagram of
outline, (b1) and (b2) are schematic diagrams of a section, and (c)
is an explanatory diagram of state of use.
[0025] FIG. 4 is an explanatory diagram showing a coupling and
supporting structure of a solar heat collecting pipe.
[0026] FIG. 5 is an explanatory diagram of a solar heat collecting
pipe, in which (a) is a front sectional view, (b) is an X-X end
view of (a), and (c) is a Y-Y and Z-Z end view of (a).
PREFERRED EMBODIMENT
[0027] A preferred embodiment of a solar heat collecting pipe of
the present invention I described below while referring to the
accompanying drawings.
[0028] FIG. 1 shows an embodiment of a solar heat collecting device
making use of a solar heat collecting pipe of the present
invention.
[0029] This solar heat collecting device includes a solar heat
collecting pipe 1 having an inner pipe 11 for receiving sunlight
collected by a trough type reflector 2 having a parabolic section
as a light collecting mechanism, and transmitting energy to a heat
medium 14 passing through the inside, and an outer pipe 12 covering
the outer circumference of the inner pipe 11 for forming a heat
insulating space 13.
[0030] In this case, the solar heat collecting pipe 1 and the
reflector 2 are mounted on a platform 3 so as to be capable of
moving the central axis L1 of the solar heat collecting pipe 1 and
the reflector 2 along the north-south axis, and oscillating the
solar heat collecting pipe 1 and the reflector 2 by way of a common
oscillating axis 4.
[0031] In addition, a sun tracing mechanism 5 is provided for
rotating the oscillating axis 4 along with the motion of the sun,
so that an extension direction of a side including a bisector L2 of
the solar heat collecting pipe 1 and the reflector 2 may be always
directed to the direction of the sun.
[0032] As a result, sunlight Sb always enters the reflector 2 in
parallel to the plane including the bisector L2 of the reflector 2,
and the reflected light is collected on the central axis L1 of the
solar heat collecting pipe 1 mounted on the position of the focus
of the reflector 2.
[0033] In this preferred embodiment, the reflector 2 is composed by
joining an aluminum plate material as a support member and an
aluminum plate member of high reflectivity as a mirror, and fitting
them into a frame member of aluminum extrusion formed material,
but, instead, a glass mirror of a flexible thin material that can
be curved may be used.
[0034] Also in this preferred embodiment, the light collecting
mechanism is the trough type reflector 2 having a parabolic
section, but it may be also realized by a Fresnel mirror type
reflector composed of a plurality of long planar division mirrors,
or a known light focusing mechanism such as linear Fresnel lens 6
as shown in FIG. 2.
[0035] In the meantime, the solar heat collecting pipe 1 of the
preferred embodiment includes, as shown in FIG. 3, the inner pipe
11 for receiving sunlight collected by the reflector 2 as light
collecting mechanism, and transmitting energy to the heat medium 14
passing through the inside, and the outer pipe 12 covering the
outer circumference of the inner pipe 11 for forming a heat
insulating space, in which a solar heat absorbing film 11a is
applied in a portion exposed to sunlight from the reflector 2 at
least on the surface of the inner pipe 11 of the solar heat
collecting pipe 1 (the portion exposed to the reflected light of
the sunlight Sb at the side of the reflector 2), and a heat
reflecting film 11b is applied in a portion not exposed to sunlight
from the reflector 2 (the portion not exposed to the reflected
light of the sunlight Sb at the opposite side of the reflector
2).
[0036] More specifically, in the portion exposed to sunlight from
the reflector 2 at least on the surface of the inner pipe 11 (in
the embodiment, the whole circumference ((b1) in FIG. 1) on the
surface of the inner pipe 11 or the range of 180 degrees at the
lower side ((b2) in FIG. 3), a chrome oxide plating layer is
applied as the solar heat absorbing film 11a.
[0037] Or the solar heat absorbing film 11a may be formed in a
limited area exposed to the sunlight from the reflector 2.
[0038] The chrome oxide plating layer as the solar heat absorbing
film 11a may be formed at a relatively low cost by forming chrome
oxide plating on the surface of the inner pipe 11 made of a pickled
steel pipe.
[0039] The material and the forming method of the solar heat
absorbing film 11a are not particularly limited, and the material
includes nickel aside from chrome oxide, and the forming method is
not limited to plating process, but includes spraying process,
physical vapor deposition (PVD), or painting, or a black color may
be applied on the surface in order to enhance absorption of solar
heat, or a proper selective absorbing film may be applied, or other
conventional method may be combined.
[0040] Further, in the portion not exposed to sunlight from the
reflector 2 (in the embodiment, the range ((b1) in FIG. 3) of 180
degrees at the upper side of the surface of the solar heat
absorbing film 11a formed on the entire circumference of the
surface of the inner pipe 11 or the range ((b2) in FIG. 3) of 180
degrees at the upper side of the surface of the inner pipe 11, an
aluminum foil or thin plate is applied as the heat reflecting film
11b.
[0041] Or the heat reflecting film 11b may be formed in an entire
area not exposed to sunlight from the reflector 2.
[0042] The aluminum foil or thin plate as the heat reflecting film
11b may be formed at a relatively low cost, by adhering by way of a
silicone resin or other adhesive agent.
[0043] In this case, by adhering the aluminum foil or thin plate by
way of a silicone resin or other adhesive agent, in addition to the
heat reflecting function, an adiabatic function of the adhesive
agent may be applied (by foaming the adhesive agent, the adiabatic
function may be further enhanced), and the energy transmitted to
the heat medium 14 may be entrapped within the inner pipe 11, and
energy dissipation may be suppressed.
[0044] The material and the forming method of the heat reflecting
film 11b are not particularly limited, and a white or silver
heat-resistant adiabatic paint having a heat reflecting function (a
function capable of entrapping the energy transmitted to the heat
medium 14 within the inner pipe 11), for example, ceramic adhesive
or silicone resin may be used as a binder, and micro-size hollow
ceramics may be contained, or heat-resistant sheet materials made
of glass wool or the like, and other conventional materials may be
also used. Or an aluminum thin plate may be bonded physically by
using any band.
[0045] The inner pipe 11 may be made of steel pipe, stainless steel
pipe, and other metal pipe, and the outer pipe 12 is preferably
made of Kovar glass pipe, borosilicate glass pipe, or the like.
[0046] The heat insulating space 13 usually insulates heat by
forming a vacuum space between the inner pipe 11 and the outer pipe
12.
[0047] The heat medium 14 passing inside of the inner pipe 11 is
water, heat medium oil, molten salt, or other heat medium
functioning as a heat medium when heated to a temperature of
hundreds of degrees centigrade, for example, about 400.degree.
C.
[0048] The solar heat collecting pipe 1 has the solar heat
absorbing film 11a applied in the portion exposed to sunlight from
the reflector 2 as light collecting mechanism at least on the
surface of the inner pipe 11, and the heat reflecting film 11b
applied in the portion not exposed to sunlight from the reflector
2, and therefore by the solar heat absorbing film 11a, absorption
of energy in the heat medium 14 passing the inside of the inner
pipe 11 is enhanced, and by the heat reflecting film 11b, energy
transmitted to the heat medium 14 can be entrapped within the inner
pipe 11, and dissipation of energy can be suppressed, so that the
heat collecting efficiency may be enhanced.
[0049] Hereinafter, the performance of the solar heat collecting
pipe is verified specifically.
[0050] [Case 1] [0051] Heating temperature of heat medium:
400.degree. C. [0052] Size of reflector: width 2 m, length 5 m.
[0053] When entire surface of inner pipe is coated with solar heat
absorbing film (chrome oxide plating layer): [0054] sx
(273+400).sup.4=11632 W/m.sup.2 [0055] s (Stefan-Boltzmann
constant)=5.67.times.10.sup.-8 W/(m.sup.2K.sup.4) [0056]
Emissivity: e=0.6, supposing inner pipe surface area: 0.534
m.sup.2, [0057] Heat radiation amount:
0.6.times.11632.times.0.534=3.73 kW (1) [0058] When entire surface
of inner pipe is coated with solar heat absorbing film (chrome
oxide plating layer), of which half circumference is coated with
heat reflecting film (aluminum foil): [0059] Supposing aluminum
foil emissivity: e=0.1, [0060] Heat radiation amount from portion
of solar heat absorbing film (chrome oxide plating layer): 1.86 kW.
[0061] Heat radiation amount from portion of heat reflecting film
(aluminum foil): 0.31 kW. [0062] Overall heat radiation amount:
2.27 kW (2) [0063] Heat amount absorbed by solar heat collecting
pipe when direct insolation from the sun is 1 kW/m.sup.2: [0064]
When entire surface of inner pipe is coated with solar heat
absorbing film (chrome oxide plating layer): [0065] Opposite side
of reflector: 10.times.25/1000.times.0.9.times.0.95=0.11 [0066]
Reflector side:
10.times.1975/2000.times.0.9.times.0.9.times.0.95=7.60 [0067]
Overall heat radiation amount: 7.71 kW (3) [0068] When entire
surface of inner pipe is coated with solar heat absorbing film
(chrome oxide plating layer), of which half circumference is coated
with heat reflecting film (aluminum foil): [0069] Opposite side of
reflector: 10.times.25/1000.times.0.9.times.0=0 [0070] Reflector
side: 10.times.1975/2000.times.0.9.times.0.9.times.0.95=7.60 [0071]
Overall heat radiation amount: 7.60 kW (4) [0072] Heat efficiency
[0073] When entire surface of inner pipe is coated with solar heat
absorbing film (chrome oxide plating layer): [0074] (3)-(1)=3.98
kW.fwdarw.heat efficiency: 3.98 kW/10 kW=39.8%. [0075] When entire
surface of inner pipe is coated with solar heat absorbing film
(chrome oxide plating layer), of which half circumference is coated
with heat reflecting film (aluminum foil): [0076] (4)-(2)=5.43
kW.fwdarw.heat efficiency: 5.43 kW/10 kW=54.3%.
[0077] [Case 2] [0078] Heating temperature of heat medium:
200.degree. C. [0079] Size of reflector: width 2 m, length 5 m.
[0080] When entire surface of inner pipe is coated with solar heat
absorbing film (chrome oxide plating layer): [0081] sx
(273+200).sup.4=2838 W/m.sup.2 [0082] s (Stefan-Boltzmann
constant)=5.67.times.10.sup.-8W/(m.sup.2K.sup.4) [0083] Emissivity:
e=0.6, supposing inner pipe surface area: 0.534 m.sup.2, [0084]
Heat radiation amount: 0.6.times.2838.times.0.534=0.91 kW (5)
[0085] When entire surface of inner pipe is coated with solar heat
absorbing film (chrome oxide plating layer), of which half
circumference is coated with heat reflecting film (aluminum foil):
[0086] Supposing aluminum foil emissivity: e=0.1, [0087] Heat
radiation amount from portion of solar heat absorbing film (chrome
oxide plating layer): 0.46 kW. [0088] Heat radiation amount from
portion of heat reflecting film (aluminum foil): 0.08 kW. [0089]
Overall heat radiation amount: 0.54 kW (6) [0090] Heat amount
absorbed by solar heat collecting pipe when direct insolation from
the sun is 1 kW/m.sup.2: [0091] When entire surface of inner pipe
is coated with solar heat absorbing film (chrome oxide plating
layer): [0092] Opposite side of reflector:
10.times.25/1000.times.0.9.times.0.95=0.11 [0093] Reflector side:
10.times.1975/2000.times.0.9.times.0.9.times.0.95=7.60 [0094]
Overall heat radiation amount: 7.71 kW (7) [0095] When entire
surface of inner pipe is coated with solar heat absorbing film
(chrome oxide plating layer), of which half circumference is coated
with heat reflecting film (aluminum foil): [0096] Opposite side of
reflector: 10.times.25/1000.times.0.9.times.0=0 [0097] Reflector
side: 10.times.1975/2000.times.0.9.times.0.9.times.0.95=7.60 [0098]
Overall heat radiation amount: 7.60 kW (8) [0099] Heat efficiency
[0100] When entire surface of inner pipe is coated with solar heat
absorbing film (chrome oxide plating layer): [0101] (7)-(5)=6.80
kW.fwdarw.heat efficiency: 6.80 kW/10 kW=68.0%. [0102] When entire
surface of inner pipe is coated with solar heat absorbing film
(chrome oxide plating layer), of which half circumference is coated
with heat reflecting film (aluminum foil): [0103] (8)-(6)=7.06
kW.fwdarw.heat efficiency: 7.06 kW/10 kW=70.6%.
[0104] Thus, as a result of verification of performance of the
solar heat collecting pipe, by applying the heat reflecting film
11b in the portion not exposed to sunlight from the reflector 2,
the energy transmitted to the heat medium 14 could be entrapped
within the inner pipe 11, and dissipation of energy could be
suppressed, and hence the heat collecting efficiency could be
enhanced, and in particular when the heating temperature of the
heat medium is higher, it has been confirmed that the heat
collecting efficiency is higher.
[0105] Further, as shown in FIG. 4 and FIG. 5, the both ends of the
inner pipe 11 are affixed by way of an expansion difference
absorbing mechanism 25 for absorbing the difference in thermal
expansion (linear expansion) of the inner pipe 11 and the outer
pipe 12, consisting of metal ring 25a and bellows 25b bonded to the
end parts of the outer ring 12.
[0106] The adjacent solar heat collecting pipes 1 thus composed are
coupled together by forming threads in connection parts 11 c of the
inner pipes 11 of the solar heat collecting pipes 1, and connecting
in non-expanding state by connection members 23 having threads
formed at both ends, and a support shaft 24 protruding in the
horizontal direction from the surface of the inner pipe 11 near the
coupled position is slidably inserted into a slit 31 in a
horizontal direction formed in solar heat collecting pipe support
members 3a1 to 3a4, 3b1 to 3b3.
[0107] In this case, at one end side or near the one end side of
the slit 31, a notch 32 opening upward may be formed continuously,
so that the support shaft 24 may be inserted into the slit 31 more
smoothly by way of the notch 32.
[0108] Consequently, the adjacent solar heat collecting pipes 1 are
mutually coupled easily and firmly, by screwing and connecting the
inner pipes 11 of the solar heat collecting pipes in non-expanding
state by the connection members 23, and the vicinity of the coupled
position can be supported while absorbing the thermal expansion
(linear expansion) of the inner pipes 11 by means of the solar heat
collecting pipe support members 3a1 to 3a4, 3b1 to 3b3.
[0109] Incidentally, the end part not coupled to the solar heat
collecting pipe 1 of thus coupled solar heat collecting pipes 1 is
formed as a free end, and, for example, by connecting a flexible
pipe 26 to the inner pipe 11 of the solar heat collecting pipe 1,
the thermal expansion (linear expansion) of the inner pipes 11 can
be absorbed.
[0110] In the preferred embodiment, the solar heat collecting pipe
support members 3a1 to 3a4, 3b1 to 3b3 are affixed to the trough
type reflector 2 having a parabolic section as the light collecting
mechanism, and the reflector 2 and the solar heat collecting pipe 1
are oscillatably mounted on the platform 3 by way of a common
oscillating shaft 4, so that the reflector 2 and the solar heat
collecting pipe 1 may be formed as an oscillating body of an
integral structure.
[0111] Moreover, the solar heat collecting pipe support members 3a1
to 3a4, 3b1 to 3b3 are provided with a function of supporting while
absorbing the thermal expansion (linear expansion) of the solar
heat collecting pipe 1, more specifically, the inner pipes 11, and
the expansion difference absorbing mechanism 25 consisting of metal
ring 25a and bellows 25b bonded to the end part of the outer pipe
12 affixed to the inner pipe 11, specifically bonded to the end
parts of the outer ring 12 is formed in a groove structure opened
upward to the ventilation space for shutting off the sunlight
exposed from the reflector 2 as the light collecting mechanism, and
releasing heat by atmospheric convection.
[0112] As a result, through the expansion difference absorbing
mechanism 25 consisting of metal ring 25a and bellows 25b bonded to
the end part of the outer pipe 12, heat conduction to the outer
pipe may be reduced.
[0113] The solar heat collecting pipe of the invention is described
herein by referring to the preferred embodiment, but it must be
noted that the present invention is not limited to this preferred
embodiment alone, but may be changed and modified in various
structures in a scope not departing from the true spirit
thereof.
INDUSTRIAL APPLICABILITY
[0114] The solar heat collecting pipe of the invention is
characterized by enhancing the heat collecting efficiency by
suppressing dissipation of energy transmitted to the heat medium
passing in the inside of the inner pipe, and hence it may be
preferably used in an application of a solar heat collecting
apparatus utilizing the solar heat collecting pipe.
DESCRIPTION OF THE REFERENCE NUMERALS
[0115] 1 Solar heat collecting pipe [0116] 11 Inner pipe [0117] 11a
Solar heat absorbing film [0118] 11b Heat reflecting film [0119]
11c Connection part [0120] 12 Outer pipe [0121] 13 Heat insulating
space [0122] 14 Heat medium [0123] 2 Reflector (light focusing
mechanism) [0124] 6 Linear Fresnel lens (light focusing mechanism)
[0125] 24 Support shaft [0126] 25 Expansion difference absorbing
mechanism [0127] 25a Metal ring [0128] 26b Bellows [0129] 3a1 to
3a4, 3b1 to 3b3 Solar heat collecting pipe support member [0130] 31
Slit [0131] 32 Notch [0132] Sb Sunlight
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