U.S. patent number RE30,407 [Application Number 06/003,466] was granted by the patent office on 1980-09-23 for solar heat collector module.
Invention is credited to Daniel J. Lightfoot.
United States Patent |
RE30,407 |
Lightfoot |
September 23, 1980 |
Solar heat collector module
Abstract
A solar heat system is comprised of a panel or bank of heat
collector modules each of which has a fluid-carrying tube of an
elongated triangular shape in transverse cross section formed with
longitudinally extended inwardly projected heat radiating fins. A
tube is mounted within a concavo-convex reflector of a hyperbolic
form such that the side walls of the tube are subjected to
reflected rays of solar radiation over an effective range of solar
exposure of about one hundred and fifty (150.degree.) degrees. The
reflected rays are concentrated in a longitudinally extended focal
zone on each side wall of the tube and these zones of concentrated
solar radiation move transversely of a side wall in response to the
angle of the solar rays falling upon the reflector.
Inventors: |
Lightfoot; Daniel J. (Glenwood,
IA) |
Family
ID: |
21706005 |
Appl.
No.: |
06/003,466 |
Filed: |
January 15, 1979 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
639847 |
Dec 11, 1975 |
04003366 |
Jan 18, 1977 |
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Current U.S.
Class: |
126/694; 126/633;
126/906; 126/623; 126/640 |
Current CPC
Class: |
F24S
23/70 (20180501); Y02E 10/40 (20130101); F24S
2023/837 (20180501) |
Current International
Class: |
F24J
2/10 (20060101); F24J 2/06 (20060101); F24J
003/02 () |
Field of
Search: |
;126/270,271 ;237/1A
;60/641 ;350/288,289,293,294 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Yeung; James C.
Assistant Examiner: O'Connor; Daniel J.
Attorney, Agent or Firm: Lowell; Rudolph L. Pingel; G.
Brian
Claims
I claim:
1. A fixed position concentrating solar heat collector module for
radiantly absorbing solar heat including:
a. an elongated housing having a transparent top wall,
b. a reflector of a concavo-convex hyperbolic shape having a
concave reflecting surface,
c. said reflector positioned within and extended longitudinally of
said housing with the concave reflecting surface thereof faced
upwardly,
d. means in said housing for thermally insulating the convex
surface of said reflector, and
e. a heat collector tube of an elongated triangular shape in
transverse cross section longitudinally mounted within the lateral
confines of the arc of said reflector having a base wall thereof
positioned upwardly and one side wall thereof arranged
substantially perpendicular to a chord extended between the
extremities of the arc of said reflector and having a vertical
dimension substantially equal to the maximum lateral dimension of
the reflector.
2. The fixed position concentrating solar heat collector module
according to claim 1, wherein:
a. said maximum lateral dimension of the reflector is in a plane
extended longitudinally of the reflector and perpendicular to and
intersecting said chord about one-third the length thereof from one
of said arc extremities, and
b. said heat collector tube is located substantially within the
confines of said one-third length of the chord with said one side
wall thereof opposite said one arc extremity.
3. The solar heat collector module according to claim 2,
wherein:
a. the linearly extended width of said reflector is about one-third
longer than the length of said chord.
4. The solar heat collector module according to claim 1,
wherein:
a. said heat collector tube has the side walls thereof about equal
in width and the base wall of a width equal to about one-third of
the width of a side wall.
5. The solar heat collector module according to claim 1,
wherein:
a. the portions of said reflecting surface at opposite sides of the
heat collector tube reflect solar rays therefrom to a single focal
zone linearly extended longitudinally of and over substantially the
full length of an adjacent side wall of said tube.
6. The solar heat collector module according to claim 5,
wherein:
a. the focal zones on said side walls move laterally of said walls
in opposite directions in response to the travel of the sun across
the sky. .Iadd.
7. A fixed position concentrating solar heat collector module for
radiantly absorbing solar heat including:
(a) an elongated housing having a transparent cover wall,
(b) a reflector of a concavo-convex hyperbolic shape having a
concave reflecting surface with a zone of maximum lateral dimension
adjacent one end thereof,
(c) said reflector positioned within and extended longitudinally of
said housing with the concave reflecting surface thereof faced
toward said cover wall; and
(d) a heat collector tube of an elongated shape in transverse cross
section longitudinally mounted within the lateral confines of the
arc of said reflector in said zone of maximum lateral dimension,
said tube having a pair of linear side walls extended between said
cover wall and said reflecting surface, and an end wall located
adjacent said transparent cover wall, with each of said side walls
being of a width substantially equal to the maximum lateral
dimension of the reflector. .Iaddend. .Iadd.
8. The solar heat collector module according to claim 7,
wherein:
(a) the portions of said reflecting surface at opposite sides of
the heat collector tube reflect solar rays therefrom to a single
focal zone linearly extended longitudinally of and over
substantially the full length of an adjacent side wall of said
tube. .Iaddend. .Iadd.9. The solar heat collector module according
to claim 8, wherein:
(a) the focal zones on said side walls move laterally of said walls
in opposite directions in response to the travel of the sun across
the sky. .Iaddend. .Iadd.10. The solar heat collector module
according to claim 7, wherein:
(a) the linear sidewalls of said collector tube converge toward
each other from said end wall..Iaddend.
Description
SUMMARY OF THE INVENTION
The relative arrangement and construction of the reflector and
fluid-carrying tube in the heat collector module of this invention
provides for an extremely efficient collection of solar radiations
which efficiency takes place over a wide angle of solar exposure
without requiring the use of tracking devices to maintain a
predetermined relation between the sun and the reflector. The
fluid-carrying tube is continuously subjected to reflected solar
rays, the radiated heat from which is concentrated in focal zones
extended longitudinally on each side wall of the tube. By virtue of
the inwardly projected heat radiating fins in the tube, the radiant
heat collected by the tube is efficiently transferred to the heat
conducting fluid in the tube for delivery into a room heating
system or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a house showing a solar heat system
in assembly relation therewith;
FIG. 2 is a partial side elevation of a house showing a modified
assembly of the solar heat system therewith;
FIG. 3 is a foreshortened perspective view of the heat collector
module of this invention which forms part of the solar heat system
shown in FIGS. 1 and 2;
FIG. 4 is an enlarged sectional view of the heat collector module
as seen along line 4--4 in FIG. 3;
FIG. 5 is an enlarged cross-sectional view of the fluid carrying
tube taken on line 5--5 in FIG. 3;
FIG. 6 is a reflected heat diagram for the solar heat panel shown
in FIG. 1;
FIG. 7 is a reflected heat diagram for the solar heat panel shown
in FIG. 2;
FIG. 8 is a diagrammatic showing of a solar heat panel wherein the
heat collector modules are connected together in a parallel
arrangement;
FIG. 9 is a diagrammatic showing of a pair of solar heat panels
wherein the heat collector modules are connected together in a
series-parallel relation; and
FIG. 10 is a diagrammatic showing of a pair of solar heat panels
wherein the heat collector modules are connected together in a
series relation.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1, there is shown a solar heating system for
a house 15, which includes a solar heat panel 16 mounted on the
southern slope 17 of the house and including a plurality of heat
collector modular units 18 of this invention. The modules 18 are
illustrated as connected in series with an inlet pipe 19 and outlet
pipe 21 connected to a hot water tank or thermal energy storage
system 22. A pump 23 in the inlet pipe 19 provides for a
circulation of a heat transfer fluid, such as water or anti-freeze
liquid, from the tank 22 for successive travel through the modules
18 and return to the tank through the outlet pipe 21. The tank
functions to store collected energy for use in a house heating
system (not shown) during the night and heavily overcast day
periods. Any number of modules may be used in a solar heat panel
for connection in parallel, in series or in series-parallel to
provide a desired heating condition.
Each heat collector module 18 (FIGS. 3 and 4) includes a housing 24
of an elongated box shape having side walls 26, end walls 27, and a
bottom wall 28 of a metal or fiber glass construction; and a
transparent top cover or wall 29. The top wall is of a double pane
construction that includes an upper pane 31 made of Tedlar, a
DuPont polyvinyl flouride plastic film having a thickness of about
four mils., arranged in parallel spaced relation with a fiber glass
transparent lower pane 32 about 0.040 inches in thickness known as
SunLite and available from the Kalwall Corporation of Manchester,
New Hampshire. Tedlar is known for its ability to withstand the
elements and has the characteristic of selectively transmitting
only the short wave frequences of light and of being opaque to long
wave infra red. The top wall 29 thus functions to prevent
re-radiation of solar rays into the atmosphere.
Mounted within and extended longitudinally of the housing 24 is a
reflector 33 of a concavo-convex shape in transverse cross section,
the concave surface 34 of which faces upwardly toward the top wall
29. The reflector 33 may be constructed of either reflectorized
sheet aluminum or stainless steel and has a curvature which follows
generally the shape of a section of a hyperbolic spiral. The lower
pane 32 lies in the plane of a chord that extends between the
extremities of the arc formed by the reflector. Thus, as shown in
FIG. 4, the maximum lateral dimension or depth D of the reflector
33 occurs in a plane normal to the chord, and located inwardly from
the arc extremity 36 a distance equal to about one-third the length
of the chord, as indicated by the letter L.
The shape of the arc is maintained by its support on transverse
form retaining members 37 mounted within and spaced longitudinally
of the housing 24. A suitable thermal insulation 38 is filled in
between the form retaining members to thermally insulate the convex
or bottom surface of the reflector 33 against the conduction or
radiation of heat toward the side and bottom walls of the
housing.
In one embodiment of the invention, the housing 24 is 7 inches
high, 20 inches wide and about 8 feet long; the reflector 33 has a
developed rectangular shape of about 2 feet by 8 feet and a chord
length C (FIG. 4) between the arc extremities of the reflector of
about 19 inches; and the panes 31 and 32 of the top wall 29 are
rectangular in shape and spaced about one-half of an inch
apart.
In this embodiment, the maximum depth or lateral dimension D is
about 61/4 inches at a distance L from the arc extremity 36 of
about 6 inches. At a distance of about 3 inches from the extremity
36 the lateral depth of the reflector arc is about 51/4 inches and
at distances of about 10 and 14 inches from the arc extremity 36
the lateral arc depths are about 51/2 inches and 35/8 inches,
respectively.
Mounted within and extended longitudinally of the reflector 33 is a
fluid carrying or heat collector tube 39 of an elongated triangular
shape in transverse cross section (FIGS. 4 and 5) having a base or
top wall 41 and side walls 42 and 43 of substantially equal length.
In the above mentioned embodiment of the invention the base wall is
about 2 inches wide and the side walls 42 and 43 are about 6 inches
wide. The collector tube 39 has the base wall 41 spaced from the
housing top wall 29 with the side wall 42 thereof adjacent to and
substantially parallel with the plane at the maximum lateral depth
D of the reflector arc. The collector tube is made of aluminum and
formed by extrusion with spaced heat radiating fins 44 extended
longitudinally of the tube and projected inwardly from the inner
surfaces of the tube walls 41, 42 and 43. The outer surface of the
tube 39 is painted or coated with a black colored heat absorbing
material, indicated at 45 in FIG. 5, such as Nextel, available from
the 3M Company of Minneapolis, Minn. This Nextel material has a
capacity of absorbing about ninety-eight percent of the heat
directed or reflected thereon. Where desired a selective coating
for the heat collector tube 39 may be used.
In the solar heat system for the house installation shown in FIG.
1, the roof 14 is illustrated with a pitch of about 30.degree. and
the panel 16 as comprised of four of the modules 18. The modules
are in a series-connection extended longitudinally in an east-west
direction on the south roof 17 of the house 15, with the arc
extremity 36 uppermost. The reflected heat diagram of this
installation is shown in FIG. 6 for sun elevations from the horizon
of 10.degree., 40.degree. and 60.degree.. At the ten degree sun
elevation, and wherein direct sun rays are indicated at 46 and
reflected rays at 47, it is seen that the reflected rays 47 meet or
concentrate at a focal zone 43a which extends longitudinally over
the full length of the collector tube wall 43 at a position
adjacent its lower end. This focal zone 43a, in the previously
referred to invention embodiment, is about one-half inch wide and
constitutes a reflected heating surface. At the same time there is
formed adjacent the upper end of the wall 42 a focal zone 42a. This
concentration of collected solar heat at opposite ends of the
collector tube 39 is quickly and efficiently transferred to the
heat conducting medium flowing through the tube by the heat
radiating fins 44.
During elevation of the sun from 10.degree. to 40.degree., the
focal zone 43a progressively moves upwardly on the tube wall 43
concurrently with a progressive downward movement of the focal zone
42a on the side wall 42 (FIG. 6) such that the heated surfaces or
zones 42a and 43a are intermediate the ends of the collector tube.
As the elevation of the sun continues, from 40.degree. to
60.degree., the focal zone 43a moves progressively to a position
adjacent the upper end of the tube wall 43 concurrently with the
progressive movement of the focal zone 42a to a position adjacent
the lower end of the tube wall 42.
It is seen, therefore, that for a 60.degree. elevation of the sun,
the focal zones 42a and 43a are in diagonally reversed positions on
the tube 39 relative to the positions therefor when the sun is at a
10.degree. elevation. Thus, for a sun exposure from a 10.degree.
elevation to a 60.degree. elevation, the side walls 42 and 43 of
the collector tube 39 may be completely traversed by their
associated focal zones 42a and 43a, respectively. Importantly, for
a sun exposure of about 150.degree., focal zones 42a and 43a are
continuously formed on the tube side walls 42 and 43, respectively.
This continuous concentration of solar heat rays on the collector
tube 39 takes place with a fixed orientation of the modules 18
relative to the sun's movement across the sky. As a result,
tracking mechanism for maintaining a predetermined orientation or
relation of a heat collector module with the sun is completely
eliminated.
In the solar heat system for the house installation, shown in FIG.
2, the modules 18, shown as four in number for the panel 16A, are
extended longitudinally in an east-west direction rigidly secured
to an upright south wall 48 of the house 15 with the arc
extremities 36 lowermost. With reference to the reflected heat
diagram shown in FIG. 7, corresponding to the FIG. 2, installation,
it is seen that the direct and reflected solar rays 46 and 47,
respectively, provide for the traverse of the focal zones 42a and
43a on the tube side walls 42 and 43, respectively, in all ways
similar to such traverse as previously described in connection with
FIG. 6.
FIG. 8 illustrates the connection of the modules 18 in parallel in
a panel 16B with the collector tubes 39 connected to a common inlet
header 49 and their discharge ends to a common outlet header 51. In
this type installation there is provided a moderate or warm outlet
temperature of the fluid in the outlet pipe 21.
Where a preheating of the water is desired to obtain an outlet
temperature of higher temperature than is provided for in the
parallel connection of FIG. 8, the modules 18 are connectible in a
parallel-series arrangement as shown in FIG. 9 with the modules 18
in the panel 16C connected in parallel and the modules in the panel
16D in series. Water supplied from the tank 22 to the inlet header
52 of panel 16C is preheated within the panel prior to its flow
from the outlet header 53 into the inlet 54 of the series connected
modules in the panel 16D. The temperature of the fluid at the
outlet 56 of the panel 16D will thus be higher than the temperature
obtained in the header 51 of the FIG. 8 assembly due to the
preheating effected by the parallel connection of the modules 18 in
the panel 16C.
Where water at a high temperature is desired, the modules 18 are
connectible in series in a pair of panels 16E and 16F, as shown in
FIG. 10. In this assembly it is seen that each panel 16E and 16F
has an inlet 57 connected to the panel inlet line 19 from the pump
23 and an outlet 58 connected to the panel outlet pipe 21 to the
water storage tank 22.
When a solar heat collector is to be used to heat air for use in a
house heating system, a grain drying system or the like, it is only
necessary to relatively increase the size of the collector tube 39
and reflector 33 of a module 18 to provide for a low pressure air
flow in the tube 39. In this instance a hot air thermal energy
absorbing system would be substituted for the tank 22.
Although the invention has been described with respect to a
preferred embodiment thereof, it is to be understood that it is not
to be so limited since changes and modifications can be made
therein which are within the full intended scope of this invention
as defined by the appended claims.
* * * * *