CA2901118A1 - Solar air heater collector - Google Patents

Abstract

An improved solar air heater collector is described herein.

Description

TITLE
Solar Air Heater Collector BACKGROUND
[0001] Solar thermal collector uses the solar power directly to heat a fluid in view of heating partially or completely a building such as a commercial building.

[0002] Solar hot water heat collectors include pipes having water therein that is heated in the collector by solar radiation. A network of pipes is connected to the collector and extends throughout the building to heat the building.

[0003] A drawback of such system is that it requires expensive and complex equipment to transfer the heat from the collector to the building. Also, such systems imply operational costs, maintenance, etc.

[0004] Solar air heater collectors are usually simpler in that they do require less expensive and less complicated equipments. However, they are usually still relatively complex in constructions and are therefore costly to manufacture.

[0005] The installation of many solar air heater collectors to get a more powerful solar heating system usually requires a complex and expensive duct work that make the overall system less efficient.

SUMMARY

[0006] An object of illustrative embodiments herein is therefore to provide an improved solar air heater collector.

[0007] Another object of illustrative embodiments herein is to provide such an improved solar air heater collector which is relatively simple in construction.

[0008] A further object of illustrative embodiments herein is to provide a solar air heater collector that can be connected in series to create a large solar air heater system made of one or many solar air heater collectors. Such a solar air heater collector is easy and fast to install, relatively less expensive and more efficient than current solar collectors on the market.

[0009] More specifically, in accordance with a first illustrative embodiment, there is provided a solar air heater collector for mounting on or beside a building having an interior, the solar air heater collector comprising:

[0010] a cover layer for transmitting solar radiation and for protecting the internal layers from adverse weather; the cover layer including a transparent sheet with or without an anti-reflection layer made of a material having a high transmission at wavelengths within the solar spectrum;

[0011] an absorber layer for collecting solar radiation; the absorber layer including a sheet coated with a material having a high absorbance at the wavelengths within the solar spectrum and a low emittance in wavelengths corresponding to a black body spectrum; a heat transfer layer for transferring the collected solar radiation absorbed by the absorber layer to an air fluid; the heat transfer layer including a corrugated metal sheet mounted between the absorber and back layers thereto; the heat transfer layer keeping a space out between the absorber layer and back layer and creating a plurality of parallel air channels; each of the plurality of parallel air channels having first and second ends in fluid communication with respectively the air intake and air outlet for guiding the air there between; the heat transfer layer being further for receiving heat from the absorber layer and for using the heat for heating the air fluid circulating in the air channels from the air intake to the air outlet;

[0012] a back layer including a flat metal sheet; the back layer being fixed to the back of the heat transfer layer for closing the plurality of parallel air channels created by the heat transfer layer;

[0013] a frame layer including profiles for maintain the cover layer and the insulation layer together, for mounting the solar air heater collector, for protecting the inside of the solar air heater collector from the adverse weather and for creating first and second air ducts between the back and insulation layers; the first air duct being defined by the air intake and it is connectable to another solar air heater collector or to the building by an air intake hole; the second duct is defined by the air outlet and is connectable to another solar air heater collector or to the building by an air outlet hole;

[0014] an insulation layer including a sheet of insulating material for decreasing the heat losses by the back of the solar air heater collector, for closing the two air ducts created by the frame layer and the back layer and for protecting the internal layers from adverse weather.

[0015] According to a more specific embodiment, the four (4) sides of the absorber sheet are bent for creating a space out between the absorber layer and the cover layer.

[0016] A solar air heater collector according to an embodiment of the present invention allows achieving high heat transfer efficiency between the solar radiations and the air to heat.

[0017] The expression "building" is not to be limited herein in any way and should be construed broadly so as to include any construction that includes walls and a roof, together defining a closed volume.

[0018] Other objects, advantages and features of a solar air heater collector will become more apparent upon reading the following non restrictive description of embodiments thereof, given by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0001] In the appended drawings:

[0019] Figure 1 is a perspective view of a solar air heater system made of three (3) solar air heater collectors connected in series according to an illustrative embodiment; the collectors being illustrated mounted to the exterior wall of a building, such as a commercial building;

Figure 2 is an isolated perspective view of the three (3) solar collectors from Figure 1; the collectors being shown without theirs cover and absorber layers;

[0020] Figure 3 is an exploded perspective of the cover, absorber, heat transfer, back, frame and insulation layers of the collectors from Figure 1; and

[0021] Figures 4 and 5 are respectively front and side cross sectional view of the cover, absorber, heat transfer, back, frame, and insulation layers of the collectors from Figure 1, illustrating the assembly of the six layers.
DETAILED DESCRIPTION

[0022] In the following description, similar features in the drawings have been given similar reference numerals, and in order not to weigh down the figures, some elements are not referred to in some figures if they were already identified in a precedent figure.

[0023] The use of the word "a" or "an" when used in conjunction with the term "comprising" in the claims and/or the specification may mean "one", but it is also consistent with the meaning of "one or more", "at least one", and "one or more than one". Similarly, the word "another' may mean at least a second or more.
[0023] As used in this specification and claim(s), the words "comprising"
(and any form of comprising, such as "comprise" and "comprises"), "having"
(and any form of having, such as "have" and "has"), "including" (and any form of including, such as "include" and "includes") or "containing"
(and any form of containing, such as "contain" and "contains"), are inclusive or open-ended and do not exclude additional, un-recited elements.

[0024] A solar air heater system according to a first illustrative embodiment will now be described with reference to Figures 1 to 3. While this solar air heater system is made of three (3) solar air heater collectors, it is not limited to such number and can be made of one (1) or another number of solar air heater collectors.

[0025] VVith reference more specifically to Figure 1, the solar air heater collectors 10, 11 and 12 are intended to be mounted to the exterior wall 21, to the roof (not shown) or on a side wall 21 of a building 20.
As will be described hereinbelow in more detail, the collectors 10-12 receive energy from the sun and that energy is used by the collectors 10-12 to heat air circulating therein. For that purpose, two holes (not shown) are provided in the wall 21, which are registered with corresponding air intake hole 40 of the collector 12 and air outlet hole 41 of the collector 10 (see on Figure 2). A fan (not shown) or another device provided for a similar purpose is provided to force relatively cool air from the interior of the building 20 to enter the collector 12 via its air intake hole 40, to circulate within the collectors 12, 11 and 10 to be heated as will be explained hereinbelow and to exit through the outlet hole 41 of the collector 10 hotter than it entered the collector 12.

[0026] The solar air heater collectors 10, 11 and 12 will now be described in more detail with reference to Figures 1 to 5.

[0027] The solar air heater collectors 10, 11 and 12 comprise a cover layer 30 including glass sheet 30-1 for transmitting solar radiation and for protecting the internal layers from adverse weather conditions, a absorber layer 31 for collecting solar radiation, and a back layer 33 including a metal sheet 33-1, a heat transfer layer 32 mounted between the absorber and back layers 31 and 33 thereto and including corrugated metal sheets 32-1. The metal sheets 32-1 bias the absorber layer 31 from the back layer 33 and define a plurality of parallel air channels 60 therebetween.

[0028] The solar air heater collectors 10, 11 and 12 further comprise a frame layer 34, including two (2) short side profiles 34-3 (or 34-5) and 34-4 (or 34-6), a long top profile 34-2, a long bottom profile 34-1 for maintaining the cover layer 30 and the insulation layer 35 together, for attaching the solar air heater collector on a building 20, for protecting the inside of the solar air heater collector from the bad weather.

[0029] A splitter profile 34-7 attached to back layer 33 and the insulation layer 35 splits the space between these two (2) layers for creating two (2) parallel air channels. One air channel is defined by the air intake duct 42 and the other is the air outlet duct 43.

[0030] The cover, absorber, back, heat transfer and insulation layers 30,

31,

32, 33, 34 and 35 and the resulting collectors 10, 11 and 12 are generally rectangular.
[0031] The cover layer 30 includes a sheet made of a material capable of withstanding high heat, such as a low iron rolled glass 30-1, which is made with a material having a high transmission at wavelengths within the solar spectrum and a low transmission in the wavelengths corresponding to a black body spectrum and low reflection surfaces at wavelengths within the solar spectrum. Examples of such glass having the above-mentioned properties include: low iron rolled glass SINATM and SINA TT-rm from Interfloat. According to the first embodiment, the thickness of the glass sheet is between about 3.2 mm and 4 mm.
[0032] The cover layer 30 is not limited to the above described embodiments and is capable of alternatives. For example, the sheet can have another thickness. It can include another glass, a composite material, TeflonTm, etc. It can be etched or coated with any material capable of transmitting more than 90 percent of solar radiation.

[0033] The absorber layer 31 includes a sheet made of a material capable of withstanding high heat, such as a metal, which is coated with a material having a high absorbance at wavelengths within the solar spectrum and a low emittance in the wavelengths corresponding to a black body spectrum. Examples of such coated metal having the above-mentioned properties include: eta plus_aITM from Bluetec and TiNOX energy CuTM from Almeco Tinox. The thickness of the metal sheet is for example between about 0.2 mm and 0.5 mm.

[0034] The absorber layer 31 is not limited to the above described embodiments and is capable of alternatives. For example, the sheet 31-1 can have another thickness. It can include another metal, a composite material, TeflonTm, etc. It can be coated with any material capable of absorbing more than 80 percent of solar radiation and having an emittance of less than 20 percent of the wavelengths corresponding to a black body spectrum.

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[0035] According to the first illustrative embodiment, the absorber layer 31 is coated with a material absorbing more than 92 percent of solar radiation and having an emittance of less than 8 percent of the wavelengths corresponding to a black body spectrum.

[0036] The four (4) sides of the absorber sheet 31 are bent for creating a space out between the absorber layer and the cover layer 30. The absorber layer 31, is attached and sealed to the cover layer 30 for creating an air tight spaced out, using a high temperature resistant silicone sealant 71 (figure 4- 5) or by any soldering, welding, sealing or fastening technique.

[0037] The sheet 33-1 of the back layer 33 is preferably made of a metal such as aluminum or copper, but can also be made of another metal or material capable of withstanding high temperatures. Example of such other material includes ceramics, refractory materials, composite materials, etc. The thickness of the sheet 33-1 can be for example between about 0.05 mm and 0.2 mm. According to another embodiment, the sheet of the back layer 33 is thicker or thinner than the sheet 33-1.

[0038] The heat transfer layer 32 includes one (1) corrugated metal sheets 32-1 that is positioned between the absorber and back layers 31 and 33. The corrugated sheets 32-1 with the absorber and back layers define a plurality of parallel channels 60 that extend along a direction parallel to the shorter side 61 of the collectors 10, 11 and 12 that extends from a bottom end which is registered with the air intake channel 42 to the top end which is registered with the air outlet channel 43.
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[0039] The corrugated sheet 32-1 of the transfer layer 32 is preferably made of a metal such as aluminum or copper, but can also be made of another metal or material capable to support high temperature.
Example of such other material includes ceramics, refractory materials, composite materials, etc. According to the first illustrative embodiment, the thickness of the sheet 32-1 is between about 0.05 mm and 0.3 mm. According to another embodiment (not shown), the corrugated sheet of the transfer layer 32 is thicker or thinner than the sheet 32-1

[0040] The heat transfer layer 32 receives heat from the absorber layer 31and uses at least a portion of that heat to heat the air that circulates in the air channels 60 from the air intake channel 42 to the air outlet channel 43.

[0041] Even though the heat transfer layer 32 according to the illustrative embodiment is assembled from one (1) corrugated sheets, it can be made of any number of corrugated sheets and of different shapes and sizes. Also, according to a further embodiment (not shown), the resulting channels 60 define a shape different than a straight line.
Also, the number, size and depth of the channels 60 may be different than those illustrated.

[0042] Even though the heat transfer layer 32 according to the illustrative embodiment includes corrugated sheets 32-1 to bias the absorber layer 31 from the back layer 33 and to define air channels 60, a heat transfer layer according to an embodiment of the present invention is not limited to this embodiment. Another metal structure can be provided to yield the above-described functionality.

[0043] The absorber, the heat transfer and the back layers, 31, 32 and 33 are assembled together by using welding technique (see Figures 4 and 5). This can be achieved using a laser welder, an ultrasonic welder, a micro arc welder, etc. Since these machines and apparatuses are believed to be well-known in the art and since the processes of welding are also believed to be well-known, these processes and the previously listed machines will not be described herein in more detail for concision purposes.

[0044] According to another embodiment (not shown), the absorber, the heat transfer and the back layers 31, 32 and 33 are assembled together using another method such as high temperature sealing, clinching, fastening (using fasteners, etc.), or else.The frame layer 34 includes five (5) profiles per collector from 34-1, 34-2, 34-3 or 34-5, 34-4 or 34-6 and 34-7 made of a material capable of maintaining, supporting and protecting from adverse weather conditions all the layers as aluminum. According to some embodiments, the thicknesses of the profiles are between about 1 mm and 3 mm and the height of the profiles are between 100mm to 400mm depending of the number of solar air heater collector to be connected in series.

[0045] The frame layer 34 is not limited to the above described embodiments and is capable of alternatives. For example, the profiles 34-1, 34-2, 34-3, 34-4, 34-5, 34-6 and 34-7 can have another thickness or height.
It can include another metal, a composite material, NYIOnTM, etc.

[0046] The profiles 34-1, 34-2, 34-3, 34-4, 34-5, 34-6 of the frame layer are attached to the cover and insulation layers 30 and 35 by using high temperature adhesive 70, 73, such as without limitations high temperature silicone sealant (see Figure 4 and 5).

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[0047] According to another embodiment (not shown), the profiles 34-1, 34-2, 34-3, 34-4, 34-5, 34-6 of the frame layer 34 are attached to the cover and the insulation layers 30 and 35 using another method such as welding, clinching, fastening (using fasteners, etc.), or else.

[0048] The profile 34-7 of the frame layer 34 is attached to the back and insulation layers 33 and 35 therebetween by using high temperature adhesive 74 as high temperature silicone sealant (see Figures 4 and 5).

[0049] According to another embodiment (not shown), the profile 34-7 of the frame layer 34 is attached to the back and the insulation layers 33 and 35 using another method such as welding, clinching, fastening (using fasteners, etc.), or else.

[0050] The profiles 34-1 and 34-7 of the frame layer define with the back and the insulation layers, the air intake channel 42. The profiles 34-2 and 34-7 of the frame layer define with the back and the insulation layers the air outlet channel 43.

[0051] The profiles 34-5 and 34-6 of the frame layer 34 have two (2) rectangular holes 37 allowing the air fluid to pass between the solar air collectors 10, 11 and 12. In a solar air heater system made of two (2) or more solar air collectors in series the first collector to the left 10 has one 34-3 profile with no hole and one 34-4 profile with holes, the last collector to the right 12 has one profile 34-5 with holes and one profile 34-6 with no hole. In a solar air heater system made of three (3) or more solar air collectors in series, the collectors in the middle have one 34-4 profile with holes and one 34-5 profile with holes. Those holes allow the air intake channel 42 and the air outlet I

channel 43 of each solar air heater collector attached in series to be connected together allowing the air fluid to run from one solar air heater collector to another.

[0052] According to another embodiment (not shown), the holes 37 in the profile 34-5 and 34-6 of the frame layer 34 have any shape such as, without limitations circular or oval.

[0053] The insulation layer 35 includes a sheet of insulation material 35-1 made of a material having a low heat conduction capable of withstanding high heat, protecting the back of the collector from adverse weather as polyurethane aluminum laminated sheet.
According to some embodiments, the thicknesses of the sheet are between about 25 mm and 75 mm. Examples of such insulation material having the above-mentioned properties include: ApfoilTM from John Manville and ThermaxTm from Dow Chemical.

[0054] The insulation layer 35 is not limited to the above described embodiments and is capable of alternatives. For example, the sheet 35-1 can have another thickness. It can include another insulation material, a composite material, StyrofoamTM, etc. It can be laminated with any material capable of protecting the internal of the collector from adverse weather conditions.

[0055] The hole 40 is made through the insulation sheet 35-1 and defines the air intake. The air intake hole 40 is in the air intake channel 42 of collector 12 (as shown in figure 2 and 3) or in the collector 10 (not shown).

[0056] The hole 41 made through the insulation sheet 35-1 defines the outlet.
The outlet hole 41 is in the air outlet channel 43 of collector 10 (as shown in figure 2 and 3) or in the collector 12 (not shown).

[0057] The holes 40 and 41 are in opposition. For example, if the hole 40 is made in the left collector 10 then the hole 41 must be in the right collector 12.

[0058] The holes 40 and 41 in the insulation layer 35 are circular in shape.
As mentioned hereinabove, the hole 41 defines the air intake of the collector 12 and the hole 42 defines the air outlet of the collector 10.

[0059] The diameter of the holes 40 and 41 may vary, depending for example on the number of collectors connected in series. For examples, the holes have a diameter between about 10 and 60 cm.

[0060] The holes 40 and 41 are not limited to the circular shape and can be for example rectangular, or else.

[0061] In operation, a fan (not shown) is connected to either the air intake hole 40 or the air outlet hole 41 so as to force the air from the building 20 to enter the collector 12 (see arrow 51 in Figure 2), to circulate in the air intake channel 42 therein (see arrows 52 and 53), in the corrugated sheet 32-1 (see arrow 54), in the air outlet channel 43 (see arrow 55,56 and 57), and then to exit the collector 10 (see arrow 58) warmer than it was before its entry in the collector 12.

[0062] Illustrated embodiments of a solar air heater collector are not limited to being rectangular in shape and can be oval, circular, square, irregular, or else.

[0063] It is to be understood that the illustrated embodiments are not limited in their application to the details of construction and parts illustrated in the accompanying drawings and described hereinabove. It is also to be understood that the phraseology or terminology used herein is for the purpose of description and not limitation.

Claims

1. A solar air heater collector as described herein.