CA1113328A - Solar collector and heat trap - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A solar collector unit of triangular transverse cross section is provided with a corrugated heat trap element on at least the rear vertical wall of the collector. The heat trap element has a V-shaped cross section, the angle of the V being in the range of about 35° to about 55°.
The heat trap element, in part, serves to increase the effective heat transfer surface of the collector at relatively little expense. Additionally, the corrugated member serves as a channel for direction of the flow of fluid to be heated through the collector.

Description

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1 BAC~GROUND 0~ THE INVENTION
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2 This invention relates to radiant energy collec- -

3 tion de~ices a~d in particular to solar energy collector ~ utilizing air or a similar fluid as the heat transfer ~edia.
S Many diferent solar colleotor device~ have be~n 6 developed in the prior art ~or collecting and utilizing 7 radia~t energy received from the sun. Typically, ~uch 8 prior ar~ devices are re~tangular boxes haYi~g glass or other 9 light t~a~spare~t ~urfaces suspended above a solar ab~orbing sus~ace which ~s oriented t~ ab~orb sun rays. In these col-11 le~t~rs a fluid is pa~sed in heat exohange relationship with 1~ the solar absor~ing surface. Such oollector devices are 13 known as flat plate collectors~
14 So~e flat plate collectors utilize a liquid ~uch a~ water as the heat transfer ~edium. Among the disadvan~
16 tages of flat plate colle~t ors empl~ring a liquid as the 17 heat transf~r medium is the need;for extensive plumbing, 18 liquid circulating pu~ps, and the like, in order to trarlsfer 19 the hea~c from thQ point of collection to the point of use.
20 These neceS~ar~y components a~d significantly ~o the cost of 21 utilizing such a solar radiation system.
22 Another type of flat plate collector uses a fluid 23 such as air as the heat transfer medium. Amvng the prob-24 lems encountered in flat plate collectors utilizing air as 25 the heat transfer s~edium is the need to provite for suffi-26 cient turbulerlce of the aix in the flat plate ~olleetor ~co 27 assur~ good heat transfer. Addi~ionally, means are recluired 28 to prevent heat loss by convection backwardly through the . . .

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2 Both types of-flat pla~e collectors have addi~ion-3 al deficiencies in that, in order ~o provide a collector

4 with a large enough heat absorption surface, it has been :~
nece sary in the past to assemble a plurality of 1at plate 6 collectors to provide a eollector area large enough to sati~-7 f~ the requirement~ of a part~ular bullding. Slnce each 8 flat plate collector has i~s own housing and insulation, 9 this modular onstruction provides for a degree of fle~
10 bility but at ~he e~pense of weigh~ and cos~ of the overall 11 solar collector asse~bly. Obviously not all roof stru~tures 12 will be able to support such signi~ica~tly high weights 1~ from jo~ing man~ collector mo~ules, and~ to cons~ruct a 14 roo structure which will support the weight adds to the 15 expense of the soLar energy systemO
16 Thus3 ~here remains a need for a ~olar collector :;
~7 unit which is more econcmical and efficient than collectors 18 encountered in the prior art.

~ Generally:speaking~ th~ solar energy collector of 21 the present lnventicn is a cavity-type collector 1lnit having 22 a vertical back wall9 a horizontal ba~e and a light trans-3 parent collector faceO The transvPrse cross-sectional con-24 figuration of the unit is triangularO This configura~ion 25 is partioularly suitable for integrating the solar energy 26 collector into the roof or atti~ structure of a house or ~7 building having a generally southerly faoing sloped roof.
28 Significantly, at least the back wall of the col-29 lector is substantially ~overed by a corrugated heat trap , .

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1~ element. Preferably a similar corrugated heat trap element 2 is provided on the base of the cavity collector as well.
3 The collector con~ains an air duct in the lower 4 par~ o the ~ro~ o~ ~h~ colle~tor ~or colt air to enter ~ into ~he ca~ityO A manifold for hot air to be removed ~rom 6 t~e cavity i located i~ the upper part o~ the bac~.space J of the cavity. The exhau~t air manifold is in com~unicatio~
8 with the chan~els provided by the walls of the corrugated 9 hea~ trap element.
Preferab ly the corruga~ions of the heat trap ele-11 ment are alternating V~shaped channels and turmels ha~ing 12 an angle formed by two sloping sides ~eeting in the range 13 o about 35 to abou~c 55 and preferably about 45.
14 Advan~ages arld other features of the invention will be apparent from the specifi~ation which follows and 16 from the drawings wherein }ike n~erals are used throu~hout 17 to identify like parts.
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19 Figure 1 is a generally schematic perspective view of a building, partially cut away, ~howing a solar 21 heating unit of this invention integrated in the roof and 22 attic strocture thereof~
23 Fi~ure 2 is a perspective view o~ the cavity solar 24 collector of Figure 1.
Figure 3 is a diagrammatic cross-sectional view 26 of a solar heating unit of the present invention.
27 Figure 4 is a diagrammatic end view of a solar 2~ heating unit Gf this inven~ion.

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1 Figure 5 is a back view of one collector of this 2 invention.
3 Figure 6 is a s~hema~ic illustration of a pleated 4 in~ulation me~ber and glazing for one ~ollector unit o~ the pr~sent i~vention.
6 - Figure 7 ls a schematic diagram ill~strating air 7 ~low thxough tha collector o~ this inven~ion.
3 Figure 8 illustrates the arrangement of air ports 9 for communicating with the corrugated heat trap member of this invention, 11 Figur~ 9 schematically illustrates one o~ the 12 advan~age3 of the presant inven~lon~
13 Figures 10, 11 and 12 illu~trat different srra~ge-1~ ments of~the collector u~i~ o the invention.
16 The solar ener~y collector illu~tratet ln the draw~
17 ing~ co~pri8es a cavity collector unit L0 having a vertical 18 rear wall ll, a horizontal base 12, ver~ical si~e walls 14 19 and ~5 and a~ inclined light transparent front wall 1~. A~ ~`
oan ~e seen ln the Figuresg the transver~e cross-section of 21 the cavi~y u~it is substan~ially triangular in co~fig~ra~
22 tion. The collector includes a coLd air duct 17 for supply~
23 ing cold air ~o cold air manifold 19 and ulti~ateLy through 24 the colle~tor in the direction of arrows 20 which is then collectod by hot air manifold 21 which feeds into duct 22.
26 The colle~tor unit preferably is inte$rated into 27 house or building s~ructure 26 in s~¢h a manner that many 28 of the structural ~:omponent of the ~a~ity serve also as 29 the tructural co~ponents of the hou~e or buildlng 26.

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1 Thus, for example9 the horizontal base 12 of the cavity2 can be supported on 2 x 6 floor joists 28. For ~he ver~i-3 cal wall support, 2 x 4 studding 29 is used. The studding 4 29 for the ba~ vertical wall 11 ~an be conveniently ~ied to the 2 x 6 rafters 30 and 100r jolsts 28. A~ is ~hown

6 in Figuxe 3, the ~ront light ~ra~parent member ~6 o the

7 solar collector is incllned ~n he same plane so as ~o be coexten~ive with and part o~ the roof 31 o~ building 26.
9 ~n the embodime~ ~hown in Fig~re 3, ~he tran~-pa~e~t sur~ace 16 conslsts of two layers of gla3c 32 and 11 33 separated by a spacer 34. ~luminum T's 37 are provided 12 ~o~ mounting the gla83 on the rafters 30.
13 A9 i show~ in Figure 2, a doo~ 36 is provided for 14 i~gre~s and egres~ into the cavity o the collector unit.
Op~ionally and preerably mean~ are prov~ded for 16 venti~g tha cavity such as hinged doors 38 shown in Figure 17 5 placed o~ the top of the vert~cal re~r wall o~ the ca~ity 18 collector 10. I:n one embodiment these doors will be manu-l9 ally operated and used only when ~he sy~e~ ~s totally inoperational, or e2Emple, when the building :is ~ot being 21 occupied during long periods of time thereby preventing 22 excessi~ely high stag~ation temperatu~es. A~ditionally, 23 depending u~on the use to which the heated air from the 24 collector is put, and depending upon the total ~ystem in 25 which the heat collector is lntegrated, ~he collector may 26 be manuall~ vented by means ~f dovrs 38 during sum~er 27 months, for example. Preferably9 howe~er, these doors 38 28 wlll be spring losded and set open at 212F there~y pro~

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1 viding protec~ion again~t high qtagna~ion temperatures 2 accumulatlng in tha c~llect~r unit.
3 The horizo~tal base 12, the vertical rear wall 4 11 and the verti¢al side wall 14 and 15 are preferably insulated surfaces having at leas~ 2" of insulation having 6 an R value of about 13. Any type of insulation can be ~.
7 used such as i~erglas~, ~rethane foams and the like.

8 A indl¢ated with ~espe~ ~o Figure 3, ~h~ ~o~t

9 inclined ligh~ transparent sux~ace ~an b~ a double pane o~ glazing. Optionally, h~wever, a s~ngle pane of glazing 11 ~ay also be employ~d. In the eve~t tha~ a single pane of 12 gla2ing 32 i~ usad, it is especially pre~erred to include 13 a pleated light transparent material 48 immediately below L4 the glazing 32 so a~ to ~inlmize convec~ion a~d radiation heat lo~sesO A diagrammatic cros~-section of such an 16 arran~ement is shown in Fig~re 6. Such a ple~ted material 17 4& can be formed, for exa~ple, from a polycarbonate plastic 18 9uch a~ Lexan or other light tran~parent plastics such as 19 polyacrylate~ and su3pe~ded by means of metal ~ingers such as s~eel finger~ (not shown) mounted on the framing for ~ur-21 face 16.
22 The internal surfaces o~ the cavity collector and 23 even the air du¢ts 17 and 22 and air mani~olds 19 and 21 24 are painted blac~ or covered by a blaok ~aterial. Option-ally, h~wever, only the surface of the verrical wall 11 in 2~ the horizontal base 12 need be blac~ and the inside sur-27 faces of side walls 14 and 15 can be c~nverted with light 2~ reflecti~e surfares ~o rhat sunlight incid nt o~ those ~9 four walls will be refle~e~ tcward ~he hea~ co~lection 3U area on the ~ertical rear wail and horiz2ntal bas~.

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1 Importan~ly, a cGrrugated heat trap element 40 i5 2 suspended below ~he hot air manifold on ver~ical rear wall 3 11. Preferably the eorrwgated ~ea~ trap 40 has a subs~an~
4 tially V-shaped er0~s sectio~O The angle of heat trap material 40 o~ the apex o~ ~he V for~e~ by two adjacent 6 extending walls that meet at a point ~ypi¢ally will be in 7 t~e range of abou~ 35~ to 55~ and preferably it will be 8 about 45. Tk.e ~eat trap member 40 can be made from a wide 9 range of materials includ~ng blaek painted li~ht weight metals such as alumin~m ~nd even black tinted plastics such 11 as black tinted polycarbonates such as Lexan. The ~crru~
12 gated heat trap member 40 preferably is also placed cn the 13 horizontal base i2 so a~ to s~bstantially cover the base.
14 A plurality of openings 42 are provi~ed in maniolds 21 and 19 so that air is in direct communication with both the 16 tunnels and valleys defi~ed by the corrugated heat trap 17 member. Also, as i9 shown in Figure 8, a metal bracke~ -1~3 46 is prsvided for mounting the heat trap member 40 on the 13 ~anifoldS for e~ample~ manifold 21.
As i~ shawn in Figure 4, cold air will be 21 transported through cold air duct 17 to cold air duct 19 22 a~d will enter into ~he cavity via openings 42. The air 23 ~hen will flow both o~er and under the corrugated heat 24 trap member 40 and upwardly toward the hot air manifold 21 for collection and return by hot air duct 22 to the build~
26 ing for use therein. The air flow pattern is shown she-27 matically in Figure 7 by arrows 20. Surprisingly3 it has 28 been found that the collector unit of this invention tends : . . .
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2 concerned. As the air temperature in the colleci:or begins 3 to rise above about 150F, air which normally would flow 4 within the valleys of ~he heat trap member 40 risas in the S collector and moves ~oward ~che front surface 16, thereby 6 rejecting some excess heat to the ambient atmosphere.
7 A~ can be seen from Figure 9, arlother important 8 advantage cf the heat trap n~ember 40 is that it efect~vely 9 ins:reasas th~ ~eat transfer surfaee of the solar collector by a signi:Eicant ac~or ~i~hout increasing the size o the 11 ca~rity. For wall ~olar aæ~uths of ~22 Lt2 to ~22 1/2~, 12 the en~i~e member 40 is ixradiated. Thus, ive effectlv~
13 heat transfe~ surace~ are provided. Indeed the heat 14 transfer area ratic is 5.23~L over that of a bare wall.
Additionally9 of course, this increase. in effective heat 16 transfer surface o,ccurs at relati~Tely little expe~se. More-17 over, the corrugated heat trap member 40 also serves as a 18 channel for tirectio~ O:e flow of air through the eavity.
19 ~hile the in~entiorl herein has b~en de~cri~ed 20 with par~ic~lar reference to a solar colleetor unit that i~
21 integra~ed into a: roof structure o~ a building, the collec-22 tor uni~ of the pre~ent invention ~an also be b~tilt a~ a 23 ~elf -supported s tru~ture for ~ounting on a flat roof such ~4 as shown in F~gure 10, or mounted or attached to the side z5 of a building9 such a~ shown in Figure 11, or indeed it 26 can be a self-stand~r~g, detached unit su~h as shown in 27 Figure 12.

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Claims (13)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A solar collector unit comprising:
a generally triangular housing member including a vertical back wall, a horizontal base, end walls and a sloped light transparent front surface for receiving solar radiation;
a corrugated heat trap member defining longitudinally extending tunnels and valleys suspended in front of at least part of said back vertical wall and adapted to receive solar radiation;
means for introducing cool air adjacent to horizontal base near said front surface; and means for removing warm air from adjacent the vertical back wall near the top thereof whereby at temperatures below about 150°F air flows through said collector in the direction from said front surface to said vertical back wall and then upwardly through said tunnels and valleys of said heat trap member, and at temperatures above about 150°F air which would normally flow within the valleys of the heat trap member rises in the collector and moves towards the front surface, thereby rejecting some excess heat to ambient atmosphere.

2. The solar collector unit of claim 1 wherein the corrugated heat trap member additionally covers a substantial portion of the horizontal base.

3. The solar collector of claim 2 wherein the corrugated member is substantially V-shaped in cross section, the side walls of which V-shaped member define longitudinally extending tunnels and valleys.

4. The solar collector of claim 3 wherein the angle formed by the walls of the corrugated V-shaped member is in the range of 35° to 55°.

5. The solar collector of claim 4 wherein the angle is 45°.

6. The solar heat collector unit of claim 5 wherein the means for introducing cold air into the solar collector unit consists of a duct which extends horizontally from the vertical back wall to the front of the collector unit and there joins a manifold extending at right angles to the duct for the entire length of the solar collector unit.

7. The device of claim 6, wherein the means for removing the hot air includes a horizontally mounted hot air manifold located at the top of the vertical wall of the collector and which manifold is connected to a duct extend-ing vertically downward from said manifold to said base.

8. The solar collector of claim 7, wherein said manifolds are provided with a plurality of apertures communicating with the tunnels and valleys of said corrugated heat trap member.

9. The solar collector of claim 8, wherein said unit is integrated into the attic of a building having a sloped roof.

10. The device of claim 9 including spring loaded air vent doors whereby said doors will open when the temperature exceeds a predetermined maximum temperature.

11. A solar collector comprising:
a housing, said housing having a triangular transverse cross section defined by a vertical back wall, a base and an inclined light transparent front wall, said housing including two vertical end walls;
a corrugated heat trap member, having tunnels and valleys and being adapted to receive solar radiation, said member located in front of at least part of said rear wall and covering a substantial portion of said horizontal base, said heat trap member having a V-shaped Gross section, the angle formed by the walls of said corrugated heat trap member being in the range of from about 35° to 55°, duct means for introducing air at one temperature into said collector in heat transfer relation with heat trap, said duct means extending horizontally from the vertical back wall to the front of the collector unit, and there joining a manifold extending at right angles to the duct for the entire length of the solar collector unit; and means for removing air at a second temperature from said collector, said means including a horizontally mounted hot air manifold located at the top of the vertical wall of the collector and which manifold is connected to a duct extending vertically downward from said manifold to said base whereby air flows through said collector in a direction from said front surface to said vertical back wall through said valleys of said corrugated member and at temperatures above about 150°F, air which normally flows within the valleys of said heat trap rises in the collector and moves toward said front surface thereby rejecting some excess heat to the ambient atmosphere.

12. The solar collector of claim 11 including a light transparent insulating member suspended immediately below said light transparent front wall.

13. The solar collector of claim 12 wherein said light transparent insulating member has a V-shaped cross section.