CA1140011A - Solar heat collector - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A solar heat collector uses elongated, tubular, outer casings, in a fixed position with respect to the solar orbit, surrounding inner tubular sections, carrying heat-conductive fluid.
The outer casings are highly transparent and the walls of the outer casings are of substantial thickness and of a high refractive index to admit solar heat energy and to focus it on or towards the inner tubular sections or tubes that are of highly conductive material and have dark, heat-absorbing surfaces.
One of the sides of the outer casings faces toward the sun. The other of the sides of the outer casings are coated with a highly reflective material to reflect any solar energy that by-passes the tubes, back to the inner tubes.
each of the casings is mounted in a substantially vertical plane, and the solar heat collector would normally con-sist of a plurality of such casings, or units, mounted side by side in a fixed plane approximately normal to the noonday, winter sun, or perpendicular to the sun's orbit.
The upper and lower ends of the tubes are connected to a system for storing or using the heat-conductive fluid after it is warmed by the solar energy.

Description

FIELD OF T~E I~VEN_TION
' This invention relates to solar heat collectors and , particularly to solar heat collectors that use a fluid to ;
absorb solar energy in the form of heat, and transmit it to a remote point for storage or use. More particularly, this invention relates to a solar heat collector using a series of fixed units, mounted vertically, side by side, in a plane per-pendicular to the sun's orbit, and having both refractive and reflective facilities for the collection of solar heat energy.
BAC~- ol Im or rHE INVENTIO~
There have been many devices proposed for the collection of solar energy, and, as time goes on, there would appear to be an ever-increasing need for solar heat energy to take the place of the diminishing fossil fuel energy.
The basic, practical, solar heat collectors in use today, particularly in private homes, use a form of flat plate of highly-conductive metal with a blackened, heat-absorbing surface facing generally toward the south~ A ser:ies of highly-conductive metal tubes are physically bonded to these plates, in ZO a pattern that effectively covers most of the area of the plates, to carry away the solar heat energy as it is collected.
This type of heat collector is simple and fairly effective, but it must have some form of insulation between the metal plate and the cold outside air to be useful.
This insulation is usually provided by a pane of glass or plastic, positioned in front of the flat plate, that establishes a layer of insulating air between the metal plate and the outside air. Double~pane glass may be needed to provide adequate insulation and to reduce condensation. The air space provided by the flat pane of glass would be difficult ~", .
~ ~o 8eal Again~ moi~ur~, and would be c~lmo~t ~mpo~ible ~o eva u-, ~ AtQ. Thi~ type o air ~paae would lnduce convection currents that would be di~icult to control, and would be an ~ne~table 108~ o eff~c~ency, The pane o~ gla8s decrea~es ~he solar ener~ ~ha~ reachec thP me~al pl~tel and the e~ficiency o~ these solar heat collec~or8 vary as the angle of incidence between the sun and the pane o.~
glass d~crease~. The8e 801ar heat collector~ a~e no lon~er useul when the sun's angle o incidence: equal~ ~he angle of reElection of the ~las~.
~- Another factor i8 ~ha~ there i8 only a cer~ain amoun~ o~
...
801a~ energy falling on a g~ven area in a ~iven time, and this ener~y, ~ver the whole area, can only raise the tempera~ure o~ the pla~e to a given, limited level. For practical purposes, this mean~ that mo~e s~ora~e ~acilitie8 are needed for a gi.ven amount o~ heat ener~y a~ the ~i~en, limi~ed, temper~ture level than would be needed ~or the ~ame amount of hea~ ener~y at a higher tempera-ture, There are 3everal ~ola~ heat colla~to~s or ~urnaces tha~
have been proposed ~hat conce~trate the ~olar enerey onto a smallex areQ. Mo~t u~e lenses or re1ectors to focus the rays o~ the ~un on~o ~ polnt or area to be heated. This provides a concentra~lon o~ ~olar heet energy ~ha~ can raise the tempera~ure at the foc~l point to almost any desired level, in a well known m~nner. The hea~ genera~ed by the~s means may be used a~ that poin~, or in some cases, may be ~ransmit~ed ~o a remote point as hot wa~er or steam.
However, almos~ all of these concen~rated hea~ collectors require ~ha~ the collec~or be direc~ed ~owards the sun a~ all times ~o focus :the so~Rr ener~y on~o the prec~sc po~nt being heated.
30 ~ Such directlon oi the ~ol,ar hca~ collec~or toward~ the eun nece~its~es a highly-precise machine that m~s~ be synchroniæe wi~h the ~un'8 or~it each d~y. T~le machine mu~ have enough : structural strength to ~uppor~ the entire collecting ~ys~e~, and have h~avy enough bea~ings ~o move ~he ~tructure agalns~ own ~riction a~ well as against the potentiai orces o~ the winds, etc l~i8 lead~ to inescapable mechanical problems and, ultima~ely, limit~ the collector sy~tem to a size and weight ~hat can be support~d, pivoted, an~ controlled. I~e mvtor~, or other mec'nan-ism or moving ~he struc~ure are, ine-vita~ly, a source o power expenditure ~hat ~can oniy reduce the ul~imate e~iciency o~ the sys~em.

su~Ax-r OF T~fE ~ V~NT~ON
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: In the subjec~ invention,~ any desired nu~lber o~ elollga~e~ .
1$ substan~ially~tubular, transpdrent outer ca~ing~ are mouIl~ed, side by ~ide, in ver~ical planes, but all in a common plane t~la~ i8 generally perl~end~cular to ~he zenith o ~he sun'~ winter orbit.
'~h9 tubular ca~ing~ should have a substan~ial thickness to provide phys~cal ~tren~h, ~he~nal insulation, and the rr~axlmwrll refrac~î~n ~0 o~ the ~un 1 8 r~ys l~o a ~iven area o~ each cas.Lng.
: An inner tubular sectiorl -- tha~ rna~ ~e a tube oi-hi~hly-conductive material, with ~ blackened heat-ab~orbing ~ur~ace ~ o~itioned along the gîven area cl~se to the otner ~ide of ~he ou~er ca8ings, away rom the sun, of each of a correq-~ondin~ one or the ou~er ~ubular casings. l~ese inner tubularscc~ons are ~illed wi~h a hea~-conductive fluid ~o arry away the heat absorbed by the tube or the fluid. ~ air space l~ay be pro-v-L~d be~ween ~he outer ca~ing and ~he inner tubular sec~io~, and may be evacu~ted.

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The a1dea o the tubular ~ca~ings away ~om the sun are coated wi~h a highly-refle~ive ma~rial, on ~h~ lnslde or the outside of the casings, ~o re~le~, back to the inn~r tubular .~ ~ec~ions, any o~ ~he solar energy th~t doe~ not imp~nge on the inner tubular sec~ion~ in the ~ir~t place.
The tubes may be con~ec~e,d, hydraulically, in parallel or in serles and the~ are, ultlmately, connected ~Q a u~ilization : sys~em wherein the heated liquid may be stored or used on demand.
Thermo8tatic means should be used to cut off the flow of fluid to ~he utilization ~ystem when the solar energy is nok enough to rai~e the temperature of th~ fluid above a desired level.
Thi~ solar heat collec~o~ ~8 simple, functional, and ~conomical. It ~an be manuactured at a relatively low cost, and it provides a relatively-high ~emperature through ~he focu~ing o~
a wlde ~trip of solar energy on a relatively-narrow, heat~absorbin~
tubular section. ~hi8 ocuain~ o~ the solar energy along the length o ~he ~ubes 1~ ~ubs~an~ially con~tant throu~hout the major por~lon o~ the ~un'~ dayllgh~ orbi~, withou~ any movement o~ the ~oll~c~or or the need ~or machinery ~or such movemen~.
Since thi~ 1~ a flxed mo~ntlng, the leng~h o~ the casings and the n~m~er o the casing8 i~ almost unllmited. The uni~s are elf-insula~in~, and the overall 8y8tem is compatible with many water ~torage or hot water heating systems. This ~y~tem provides it~ own gravl~y, fluid circulation. I~ i~ struc~urally strong, easy to main~ain, a~d architecturally a~tractive. It is also quite flexi~l~, in that units can b~ added, a~ needed, ~o increase the amount o~ hea~ en2rgy produced, or remo~ed for rspair 9r repla~ement, i~ nece~sary.
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In accordance with a particular embodiment of the lnvention, a solar heat collector comprises at least one elongated, tubular, outer, casing of transparent materîal;
means for positioning said outer casing in a fixed plane substantially perpendicular to the winter solar orbit, with one cylindrical side of said outer casing facing said solar orbit, whereby a substantial portion of the solar heat energy impinging on said outer casing is refracted towards a given portion within said tubular outer casing, said given portion being located between the axis of said cylindrical side of said outer casing and the other side of said outer casing' reflective means applied to said other side of said tubular outer casing; a single elongated tubular section positioned along said given portion within said outer tubular casing, said elongated tubular section having one side toward said solar orbit along the axis of said cylindrical side of said tubular outer casing, and an other side, away from sai~ solar orbit, adjacent to said re~lective means, whereby subs-tanti~lly all of said solar heat energy will be refrac-ted or reflected to said tubular section during said solar orbit; a heat-conductive fluid contained within said elongated tubular section; heat absorbing and conducting means associated with said heat-conductive fluid for applying said solar heat energy to said fluid within said tubular section and means for connec-ting said elongated tubular section to a system for using heat-conductive fluids~

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- ~a -14~Q~l , 3RIEF DESCRIPTIOW OF TIIF. DRAWINGS
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Figure 1 shows a C~065 sec~ion G~ a por~ion of a varia-~ion o~ a typical 801ar heat collec~or in accordance wi~h ~hls -in~en~ion; .
~ igures 2, 3 and 4 sho-~ cross sections o~ v~riation~ o~
5 the lndi~idual u~its of 8UCll a collector;
Figur~ 5 ~how6 a cross section o~ a portion o~ anotlle~
varia~lon of such a heat collec~or; and Figuxes 6 and 7 8how pro~iles o~ typical homes ~i~h sola~
h~at collector~ o these types.
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DETA~.LED D~SCRIPTION
Ra~erring ~o the drawin~, a varia~ion o a 801a~ hea~
collec~or in accordallce with ~his inven~ion, has uni~9 lOA, lOB, e~c. rnount~d in a ~ubstantially 1at plan~, acing ~he or~i~ o~
15 the sun's ~ays 11. The un~s coD.lprise elonga~d, ~libular outer, optical ly-r2~racti~e casing~ 12; re~lec~ive m~erial 14; and C02l-ductlve ~luid 24, ~hat rnay be con~ined in ~lon~ated ~ubular sec-t~.on~ or tubes 20. A apac~ l~ may be provided ~or insulation between ~che casin~,s 12 and the tubes 20, and this ~pace may be 20 eva~uated .
In Figurea 1 j 2 ~nd 3 ? tke casin,,~ 12 are subs tantially tubular, and contain the tubes 20 chat carry the ~luid 24, Tu~es 20 may have an outer, blaclcened, heat-absorb:Lng sur~ace 22.
Figure 2 show~ ~he re~lec.Live ma~er:lal 14 on the ou~er 25 au~ac~ o~ the caslng rather than on th2 ~rmer ~ur~ace o~ the casing as ~hown in figures 1 and 3. Thla figure also shows thac glass or plas~ic ~ube 26 may be used with a darkened liq~id 28, and 'cha~ the inrler tubular section may have a more e~icient location in the lower portion o~ ~he outer tubular casing.
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Figure 3 shows the metal~ic inner tube 20 again, but off-center with respect to its outer casing, in a location similar to that of Figure 2 Figure 4 shows a species wherein the space 16 between the outer casing 12 and the fluid-carrying tube 20 is eliminated for simplicity and economy~ The darkened liquid 28 again collects the solar heat.
Figure 5 shows a variation of the species of - Figure 4 wherein the casings 12 are molded together or joined to provide multlple units lOA, lOB, etc. In this case, the sides of the units away from the sun are flattened and a continuous reflective surface 14 can be used. This figure shows that a heat absorbing surface 22 may be applied to the walls of the inner tubular portions, or that a darkened liquid 28 may be used to absorb the solar energy.
Figure 6 shows a profile of a typical house 30 with a relatively steep roof 31 whereon a solar heat collector 10 can be mounted and can conform, esthetically, with the outline of the structure of the house. An "A
frarne" structure, not shown, would also be ideal for this purpose~
Figure 7 shows a profile of another typical house 30 with a relatively flat roof 31 that would not be parti-cularly suitable for a heat collector mounting. Here, a solar heat collector 10 can be mounted on a side wall 32 ~ ~ 7 ~

Figure 7 also shows the other elements o~ a typical solar heat collecting system, which would include a fluid storage container or tank 40. A pipe 43 connects the upper openings of parallel-connected tubes 20, not seen, to an inlet 44 to the tank A pipe 45 connects tha lower openings of the parallel-connected tubes 20 to an outlet 46 of the tank, through a valve 47. A by-pass pipe 48 should be provided through the valve 47, shown in a closed position, to permit the thermal circulation of the fluid in the tubes, as soon as the solar energy strikes the units, without the possibility of cooling the already-heated fluid in the storage tank.

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A thermos~at 49 in the by,-p~s~ pipe 48 control.s ~he valve 47 to keep the vRlYe closed and block the flow oP fluid rom the ~ube~ to the tank unt~l the temperature o the fluid flowing through the by~pa~s tu~e 48 i9 above ~ pre-~et level, or that of S ~he fluld in the ~ank. When ~he ~emperature Gf the fluid through the by-pas~ i~ above the pr~-~et level, the valve 47 i~ sw~tched to its altern~te open position, and the heated fluid flow~ into ~he storage tank. The thermo~at and the val~e csn be in either th~ outlet pipe~, as shown, or in the inlet pipes, or in both.
In Figure 7 it i8 noted t,hat the plane o~ the collec~or O
i~ ~he same a3 that of the wall, which would provlde architectural s~ructural, and es~hetic advantages that might be mor~ important than the ~light loss of efective solar heat due to the ~ew degree o~ o~set o~ the sun's rays in mid-wanter. The ~everal degrees o~ offse~ in the spring and fall wouLd be le~s signi~ican~, since ~he hea~ requirement~ would be rela~ively lower, and ~he summer losses would no~ be impor~an~.
While khe heat collector need not poln~ directly at ~he sun, or 1~8 orbit, varia~on~ should be toward ~he ~ertical ra~her ~han the horizon~al. A horizon~al placement would ~end ~o collect dirt and debri~, and ha~e le~s gravity ~low o~ the h~ated fluids wi~hin ~he tubes. Also the tran~ition b~tween ~ummer and win~er solar orbits and an~les would be les~ desirable, with more heat in ~he summer and les~ in ~he winter.
To illustrate the principle of thi~ solar heat collector, typical 801ar rays ll are shown in ~igures 1 and 5. Since the~e ~igure~ are cross section~ of substantially vextical cvllectors, ~acing south, ~he rays 11 indica~e various posi~ions o~ ~he ~un ~rom ea~ (le~ hand) to west (rL~ht-hand). 'rhe ~olar rays 30 ~iking the cQntral portion~ ~long the axe~ o~ ~he casings 12 ~ : ~

. wlll pas~ straig~t throug~h to the tubes 20, or will be re~racted .` enou~h ~o st~ike the hea~ absorbing ~ur~ace~ of the tubes. The ~olar rays s~riking the outer casing~ ~ur~her o~ center ma~ not b~
re~racted enough ~o hit the tu~es 20, bu~ will hi~ t~e re1ective sur~aces 14 and be re~lec~ed back to the rear surface~ oi ~he ~ubec ~0, wh~ch are al~o coated wi~h h~at absorbin~ material 22.
Between the re~ractive a~d ~he re~lective portion~ of eacll un~t, it will be seen that almos~ all of the solar energy : ~alling on ~he collector is concentrated on the flu~d contalning tubes.
The focusin~ o~ ~he ~ola~. energy on~o ~he hea~ absorbing ~ubes will depend on the thickness and the index o~ re~rac~ion of the tubular casing material. Bo~h should be as great ~s possible wi~hou~ significan~ 10~8 in ~ran~parency, since, ob~iou~ly, any 15 10BS in transpa~ency would decrea~e the ef~iciency o the ~ys~em.
The sharper thQ focus, and the greater ~he ra~;io be ~ween ~che diameters of ~he ou~r casin~ and ~h~ heat ab~orbin~ tubes, th~
h~gher the conc~ntrations o~ solar heat energy 1~ ~he ~lu~d and the hlgher the ~empera~ures ~ha~ can be reached.
Th~ ~ize ~nd ~he plac~rne~t of the me~allic ~ube~ Z0 can Al~o be v~rie~ to ~ome degre~ ~o recei~e the maximum concentra~ion of the solar ener~y over the ~rea~er por~ion o~ ~he solar orbit.
Although ~hig concep~ is based on an ef~ee~ive ~OCU8 0~ solar energy on~o a narrow cen~ral portion vf each unit over a substan-~lal portion of the sun'~ orbit, for all prac~ical purposes, only about n1nety de`~ree~ o~ ~he 8Un 's orbit may be use~ul. I~ may be more efec~i~e ~or o~ienta~ion of ~he elemen~ ~o fa~or ~lle ~laxi-mu~ u~e of the ~41ar hea~ energy ~nder op~im~ condl~ions. A
rigorous concentricity may no~ be ~he best compromi~e.
The op~lmum siz~ ~nd ~hap~e o~ ~h~ i~mer tubular por~ion ~ Q~

20 will depend on the actual por~ion o~ the solar orbi~ ~ha~ i~
worth con~idering. A~ ~he ~un set~ ~he solar energy must decrease and as the angle o~ incidence of the ~olar beams decrease, in any rigid collector, the efficiency mu~t decrea~e. Conseq~ently, ~he decreasing solar energy and decreasin~ e~ficienc~ lead to a practical limi~ of effective orbit. In other word~, there would be no poin~ in ~rying ~o make variations in ~he de~ign ~o accommo-date extreme angle~ of solar orbi~, if such variations would decrease the efficiency of ~he collector through the prime, eèn~ra portion of the solar orbit.
Since bo~h refractive an~ reflective ~ocusing o~ the sun~ rays are involved here, the maximum e~ficiency would be achieved by loca~ing the inner tubular portion 20 where either refracted or re~lected rays must 6trike ~his portion. If the lS inner tubular portion is of too Iarge a diameter, or substantially above the central axis o~ the collector, some of the energy that could have been reflec~ed back ~o the tubular port~on stri.kes it direc~ly. I~ the ~ubula~ portion is too small, both direc~ and re~lected rays can miss it entirely.
The irreducible ~iz~ ~nd the op~mum posi~ion of th~
inner tubular portion 20 would then appear to be with it~ one side ~acing the ~un about tangent to a llne, such a~ 29 of ig1lres 2, 3 and 4, ~hrough the center o the tubular s~ructures, ~epresentin the lowe~t angle ~o,. practical solar heat collection. For practical purposes, again, ~his minimum angle may be chosen as tangent to the outer ~ubular casin~ of ~h~ adjacent collector.
I~ the tubular portion 20 were below this line, both the direct and the reflected rays at 29 would miss the lnner tubular portion. When the tubular portion me~ts thi~ line, all the rays abovQ thi~ line will be ~efracted apd xeflected bac~ to the inner tubular portion, and all rays below th~s llne will s~rik~ the /

inner tubular portion directlya The ot~ler side of the tubular portion away from the sun should be close enough to the re~lec~
tive means of the outer tubular casing so that no reflected rays can by-pass the inner ~ubula~ portion.
Any larger inner tubular portion would be redundant, more costly, provide less concentration of solar energy and be less efficient. Any smaller inner tubular portion would lose some of the solar energy, and also be less efficient.
Nevertheless, the appli(cant does not wish to limit him-self to this precise geometry, since larger or smaller innertubular portions will function adequately within the teachings of this invention. For example, larger tubes would provide a greater flow o~ water at lower temperatures, and other sizes and shapes and configurations may be preferable for other reasons.
When separate inner tubular portions, or tubes, are employed, as in the Fi~ures 1, 2 and 3, they may be of metal, as in figures 1 and 3, or of glass or plastic as in Figure 2 The metal tubes would have advantages of strength and might simplify the plumbing par~ of the collector, but they would pre-sent problems in vacuum sealing because of the differences in thermal expansion~ However, this might be overcome by slip joints or flexible gaskets of well known types. Also a portion, or the entire length, could be a form of tubing identified by the trade mark Sylphon that could easily ac~ommodate the diff-erences in expansion between the inner tubular sections and the outer casing. The Sylphon tubing might increase the resis-tance to the flow of fluids, but it would also provide an in-creased surface area for absorptive coating, and similarly, for transfer of heat to the fluid 24.

The glass tube 26 of Figure 2 would not present a problem in thermal e~pansion for bonding of hermetically sealing of this lnner tubular sec~ion to ~he outer caaing 12 or a permean~
vacuum. A~ no~ed earlier, the liquid in such a tube could be dark enough to absorb the aolar energy. Alterna~i~ely, ~he tu~e itsel could be ~f a darkly colored glasa, or ~he lnside sur~ace o~ ~hP
~la~ tube could be coated wlth an absorp~ive coak~ng, ~uch a~ 22, not shown he~e, as ~n 22 o~ Figure 5, that would provide the n~cessary heat transfer wl~hout e~fecting ~he expansion of the gl~88. ' .: ~
The coating 22 on the ou~.~lde of ~he me~allic ~ubes 20 should be ~he mos~ ef~ective, and the most efficien~ available.
A blackened ~urace will be eff~ct~ve of course, but a selective surace material that a~sorbs both direc~ and reflec;~ed energy --but minimiæes radia~ion of ~he heat energy -- will be prefera~le.
Such a coating would al80 be applîcable to the interior linlrlgs ~uch as 22 of ~igure 5, and would al90 be applicable to the species o ~igures 2 and 4, For ~he out~r ca~ings, gl,a5s tubes are readily available and would be quite ~ati~acto~y, bu~ plastics may be leas ~ra~ile and less likely to be damaged by ~empera~ure changes or mechanical pre~sure. Pla~ic~ may also hav~ hi~her indice~ o~ rQfraction, whlch, along ~l~h ~ransparency would be deairable here. Plastic~
may al~o lend themselves more readlly to varia~ions in ~he uni~
size and shape, and to mul~iple-unit constru~ion. A combination o~ glass and plastic layers, with or without additional air spaces, cou~d~also be used.
The specie~ of flgures l to 3 show an a-lr space 16 be~ween ~he outer casings 12 and ~he tubes 20 or 26. In ~hese spacies, the upper and lower ends o ~he tubes and casings would b~ sealed, herme~ically if ~eces~ary, ~o control the air space.
Thi~ space would reduce th~ weight o~ the indi~idual uni~s, and, ` ~ Q03~
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po88ibly, ~he ~aterial co~, bu~, ~o~t importan~ would provlde a considerable and valuable insulat~on ~actor between ~he 1uid-~illed, hea~-coll~c~ng tube~ 20 or 26 and th~ outer air.~ Thi3 ~nsulation might be enough to preclude any urgent need for addi-tional outer ~las~ or plas~ic layers to provide air ~pace andin~ulation. .
Mor~ importan~, thi~ air space can be evacua~ed to a relatively high degree because of the op~imum tubular m~chanieal configuration and ~he po~ential thic~ness of ~he wall~ o~ the ~ubular casings. This evacuated space would provide obvious improvements in lnsula~ion and additional substantial reduction of heat losse~. These 6mall air space~ 16 can, in any case, be con-trolled very ea~i~y with dehydrati~g agents to reduce the po89i-bility of condensation that could be a problem with this or any o~he~ 8 srstem, Where ~epara~e tubes and casin~ are used, as in figures ; '1, 2 Rnd 3, the po~l~ion and con~iguration of the air ~pace~ 16 wl 1 be predictable. However, air spaces can al~o be pro~ided in ~he ~p~cie~ o~ ~lgures 4 and 5, par~icularly in the critlcal region be~ween ~he outcr ~ur~aGe o~ thé onc 8ide of the ou~er casing, and ~he ~ubul~ ~ection. A typical example of thls i9 seen in the air ~pace 16 shown in u~it lOB of Figure 5.
The spec~e~ of figures 4 ~and 5 may no~ need to have the air sp2ce, and ~hey do prov$de a much simpler configura~ion and a rela~ively ~hicker wall o ca~ing materlal. Wlth the lower heat conductivity o ~ome plastics, and the mechanical and cost advantages that are inherent ln these ~peciesj the probable increase in heat lo~ses due to conductivity and contact with ~h~
outer sir ma~ be ou~weighed by the other advan ages.
In these ~pecies, a ~hin, conductive tube, not shown, . .

" 13 ~ ~1.14~

may be embedded ~n t~e plast~, or a tubular sectlon may be pro-vided withln the plastic, for carrying the fluid 24. Such a tubular ~ection may be lined wi~h a heat-absorbing, conduct~-ve material 22 to trRnsmit the ~olar heat energy to the fluid, : S Alterna~ively, a dark, heat-absorbing fluld may be used, to absorb thQ solar heat energy~
.~ These ~pecies lend them~elves ~o extrusions, or ~o .
molding~techniques, with obviou~ manu~acturlng advanta~e~. There i~ also les~ limita~ion a~ ~o the ~iæes and tha numbers of tube~
lQ and casings tha~ may be provided, except that the ~maller the diameter o~ the ~luid carriers, the more impedance ~o the fluid flow.
Extrusion or moldln~, techniques lend themselves to multiple unit8, a~ seen in Fi~ure 5, alon~ wi~h many other varia-tio~s tha~ sugge~ ~hemselves. The shape o~ ~he side ~oward the ~un may be varied for maxlmu~ effective u~e o~ ~he ~olar energy, and ~he ~hape o~ the ~de away from the sun ma~J al80 ~e varied ~or ~he moBt e~ective re~lection of stray solar ener~y back ~o ~he tubul~r ~ec~ion~.
It may be des~rable to p~ovide multiple unl~ or economy o~ manu~cture, con~truc~ion, and a~3embly. I~ will be much ea~ier ~o pu~ up a ~ew, pref~brica~ed panel~ ~han ~he equiva-lent number of 8in~,1e unit~.
With extrusion technique6, it would al80 be possible to include an air ~pace of any desired ~iæe and shape, between the ~olar ~ide o the casing and the tubular ~ection that carries the fluid. Thi8 type of air sp~ce ~ mentioned earlier ~ een in Figure 5. Thi8 ~pace, which ean ~e~y ea~ily b~ sealed at the ends, and ln ~ome cases, evacuated, would incr~a~e the e~flciency of the~e collectors and reduce the overall wei~ht wi~hout ma~erially ~ ~ : ~ ~

increa~ing the unit co~. Variations of ~his will ~UggQSt them-~elveg ~o anyone qkilled in the ar~.
The reflec~ive ma~erial 14 may be deposited in~ide o~
the ca8ings a~ 9hown in fi~ure~ 1 and 3, but it may also be S deposited or applied on the outside of the casing, as shown in F~gurc 2. ~t may al~o be applied in ~heet form along the backs o~
the ca~ing~ in a curved ~orm, or in the ~lattened foxm o the unitc o~ Figure 5.
If a heat collector of t~is type were to become, physi-cally, the oute~ ~all o~ a house, fo~ economy of constructlon, ore$~hetic reasons as well as for he2ting considera~ions, the reflective 6urface 14 could, in fact, be con~rollable, ~o permit thQ choice of letting a certain amount o~ llght filter into ~he room, or reflecting all of the solar energy ~ack to the collector tubes.
The slæes o~ the tubular sections would be dictated by the ~ocuaing ~f~c~ that i9 practical ~hrough the casings and the re1ective ~urface9; the tem~era~ure le~el that ig desired; the Bize o~ the ~nterior o the casin~s; and the arnoun~ o~ alr space ox vacuum tha~ may be required ~or highes~ ef~iciency. The posi-~lon~ o ~he tubular ~ectlon~, a8 noted earlier, and the~r shape3, m~y alBo be ~a~ied to be in the optimum ~ocus of ~he ~un's ray~
dl~ing tha op~imum hea~ collectin,~ ~ime.
I~ separa~e tubes are used, ~he walls o~ ~he tùbes must be h~ghly conductlve and a8 thln aR pos~ible without sacrificing the stren~th necessary ~o ~uppor~ the ~luid and wi~hst~nd its pressure. Spacer~ would presumably be needed alon~ longer unit~
to 8UppOr~ the tuhe and maintain uniform spacing wi~h respec~ to the casing. Such spacer would have negligible losse0 and could reduc- undesir~ble con~ection currents where the air ~pac~s are not . ~:

~ ~ : ~

evacu~Qd.
The ou~r casings ar~ ln~ended to be ~xposed dire tly to th~ outside air, and presumably, would be mounted on a roo~ or wall on ~he ~outh ~ide of a house. In new construction, the hou3e can be orien~ed ~o ~hat one side faces south and the heat collecto i~ in an optimum po8ition, ~hermally, as well as es~he~ically.
Sol~r energy ~alling on the collector can be upplemen~ed by re~lecting pools or the like in a well known manner~. .
I~ the ~pace~ between th~ uni~s o~ Figure 1 are~ealed by a compound 18, a~ ~een in Figure 1, or mul~iple ~its are pro-vidQd, a~ in the 6pecies o~ Figure S, lt is apparent that the heat collector can be made air ~lght and water tight, and can be the actual outer wall -- certainly the siding, if not a st~uctural wall -- of the house, with obvious cost advantage~. The heat collec~org may be tilted to face the win~ar solar orbl~, or ~hey may be ver~ical a~ seen ~n Figure 7.
Addi~ional heat m~y be geperated by longer unlts or by addi~g additional uni~s, but, where ~pace ~ at a premium, more eiciency may be hacl through be~er in~ulation o~ ~he individual unit~. Beside~ ~he high vacuum lnsula~ion space that i~ po~gible wi~h this concep~, addl~ional, ~ransparen~, concentri~ ~asings, no~ shown, which may also have an evacuated air space, may be provided, Alternatively, this solar heat collector can be po8i ~ioned bah~nd a conven~ional insula~lng pane o~ glass.
The ~luids that would be applicable here would include almost any heat conductive liquids. Water would be an obvious cholce because o~ lts availability, low cos~ ~nd compatibili~y wl~h existing ho~-water hea~ing systems. Anti~reeze mixtures may be nece~ary~w~ere ~reezing would ~e po~slble in ex~remely cold condition~ and during p~rlod~ o~ lack o~ solar ~nerg~. Darkened fluids, as noted earlier, are also suggested where the sunlight strikes the liquid directly, ; With relatively-long vertical tubes, and low-friction connecting pipes, gravity circulation will be predictable and adequate. However with longer lines between the heat collectors and storage units, or where the friction of the pipes or other factors suggest more circulation, water pumps of well known types can be used in a well known manner, This solar heat collector can obviously be used to warm water for domestic purposes, in either winter or summer.
The ends of the casings and the tubes of each unit must be sealed hermetically if a vacuum space is intended,and any of the many couplings between glass or plastic and metal would be applicable here. Similarly, the couplings between the tops and the bottoms of the tubes and the rest of the fluid system could be standard plumbing fittings.
It is to be understood that I do not desire to be limited to the exact details of construction shown and des-cribed, for obvious modifications will occur to a person skilled in the art.

Claims (11)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A solar heat collector comprising at least one elon-gated, cylindrical, tubular, outer, casing of transparent material;
means for positioning said outer casing in a vertical plane and in a fixed plane substantially perpendicular to the winter solar orbit, with one cylindrical side of said outer casing facing said solar orbit, whereby a substantial portion of the solar heat energy impinging on said outer casing is refracted towards a given portion within said tubular outer casing, said given portion being located between the axis of said cylindrical side of said outer casing and the other side of said outer casing;
reflective means applied to said other side of said tubular outer casing;
a single elongated cylindrical tubular section posit-ioned along said given portion within said outer tubular casing, said elongated tubular section having one side toward said solar orbit along the axis of said cylindrical side of said tubular outer casing, and an other side, away from said solar orbit, adjacent to said reflective means, whereby substantially all of said solar heat energy will be refracted or reflected to said tubular section during said solar orbit;
a heat-conductive fluid contained within said elong-ated tubular section;
heat absorbing and conducting means associated with said heat-conductive fluid for applying said solar heat energy to said fluid within said tubular section, and means for connecting said elongated tubular section to a system for using heat-conductive fluids.

2. A solar heat collector as in claim 1 wherein said elongated tubular section is a hole through said outer casing.

3. In a solar heat collector as in claim 1, at least one elongated space within said casing, positioned between said cylindrical side of said outer casing and said elongated tubular section, to provide insulation between said heat-conductive fluid and the atmosphere on the outside of said cylindrical side of said outer casing.

4. A solar heat collector as in claim 1 wherein said single elongated tubular section is a separate tube of trans-parent material.

5, A solar heat collector as in claim 1 wherein said heat absorbing and conducting means is a dark colored material within said heat-conductive fluid.

6, In a solar heat collector as in claim 3, means for sealing the ends of said elongated space between said cylin-drical side of said outer casing and said elongated tubular section, at both ends of said outer casing, and means for evacuating said elongated space.

7. A solar heat collector as in claim 1 wherein said heat absorbing and conducting means is a coating on the walls of said elongated tubular section.

8. A solar heat collector as in claim 1 wherein said elongated tubular section is a separate tube of highly-conductive material, and said heat absorbing and conducting means is a coating on the outside of said separate tube.

9. A solar heat collector as in claim 8 wherein said separate tube of highly conductive material includes at least a portion of sylphon tubing to compensate for the differences in thermal expansion between the material of said outer tubu-lar casing and said elongated tubular section of highly-conductive material.

10. A solar heat collector as in claim 1 having a plurality of said elongated tubular casings mounted, side by side, in a plane perpendicular to said solar orbit;
means for sealing the spaces between adjacent casings, and means for coupling said elongated tubular sections together.

11, A solar heat collector, as in claim 10 wherein said adjacent sides of said outer casings are substantially flattened and joined together, and said other sides of said outer casings are substantially flattened for compactness and material savings, and said reflective means is a con-tinuous layer of reflective material along said other sides of said outer casings.