CA1162735A - Solar dryer and module therefor - Google Patents
Solar dryer and module thereforInfo
- Publication number
- CA1162735A CA1162735A CA000388880A CA388880A CA1162735A CA 1162735 A CA1162735 A CA 1162735A CA 000388880 A CA000388880 A CA 000388880A CA 388880 A CA388880 A CA 388880A CA 1162735 A CA1162735 A CA 1162735A
- Authority
- CA
- Canada
- Prior art keywords
- module
- modules
- air
- tube
- absorber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000006096 absorbing agent Substances 0.000 claims abstract description 25
- 239000000463 material Substances 0.000 claims abstract description 11
- 238000001035 drying Methods 0.000 claims abstract description 10
- 239000011159 matrix material Substances 0.000 claims abstract description 7
- 239000002657 fibrous material Substances 0.000 claims abstract description 4
- 239000011343 solid material Substances 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 claims description 2
- 239000007787 solid Substances 0.000 abstract 1
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 241000287828 Gallus gallus Species 0.000 description 1
- 241000533293 Sesbania emerus Species 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229920006289 polycarbonate film Polymers 0.000 description 1
- 229920002620 polyvinyl fluoride Polymers 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B3/00—Drying solid materials or objects by processes involving the application of heat
- F26B3/28—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun
- F26B3/283—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun in combination with convection
- F26B3/286—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun in combination with convection by solar radiation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B40/00—Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
- Y02B40/18—Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers using renewables, e.g. solar cooking stoves, furnaces or solar heating
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Sustainable Development (AREA)
- Toxicology (AREA)
- Microbiology (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Drying Of Solid Materials (AREA)
Abstract
Abstract A solar dryer for particulate solids such as coffee, grain or the like, passes heated air from a series of solar modules into a drying chamber, the top of which is formed as a perforate tray for supporting the material to be dried. Each solar module consists of a rectangular tube formed from insulating side and bottom walls and a translucent film extending across the top. Inside the tube is an absorber to generate heat from solar energy that passes through the film and impinges on the absorber. The absorber divides the tube into upper and lower chambers, while being inclined from one end to the other of the tube whereby the inflow air passes solely into the upper chamber and the outflow air passes solely from the lower chamber. In between, the air must pass through the absorber, which is a pervious matrix of fibrous material, to be heated thereby. The result is a dryer of improved simplicity and efficiency.
Description
2 ~ 3 5 This invention relates to a solar dryer suitable for drying particulate solid material, such as coffee, grain or the like. The invention also relates to a solar module for heating air by solar energy for use in such a dryer.
The object oE the invention is to provide a dryer of this type having improved efficiency and simplicity, and especially a dryer that is suitable for manufacture, erection and use in small centres or remote areas with limited energy sources.
The heart of the dryer is a new solar module for converting solar energy into heat and transferring such heat to air that is caused to flow through a series of such modules and then over the material to be dried.
More specifically, this module consists of ~a) an open-topped channel deEined by thermally insulating walls, ~b) a translucent film extending across the top of the channel to form a tube having an inflow port and an outflow port at its respective ends, and (c) an absorber comprising an air pervious matrix of fibrous material extending along and across the tube beneath the film to receive solar energy transmitted through such film and to convert such energy into heat, the absorber dividing the tube into an upper chamber and a lower chamber while extending along the tube so that the inflow port communicates only with one of the chambers and the outflow port communicates only with the other of the chambers whereby air travelling between the ports must flow through the absorber to collect heat therefrom.
Preferably, the inflow port communicates with the upper chamber and the outflow port with the lower `~ chamber. Also the absorber is preferably arranged at an inclination to the direction of extent of the tube.
2 ~ 3 5 The invention also relates to the overall assembly of a series arrangement o~ such modules as part of a dryer that also has a system for forcing air along the series of modules and then through the material to be dried.
In its preferred orm, this dryer has the modules arranged as a protective roof over the drying chamber which receives the heated air and has a perforated tray across its top for supporting the material so that the air can pass up through it.
Embodiments of the invention are illustrated by way of example in the accompanying drawings, in which:
Figure l is a plan view of a solar dryer embodying features of the invention;
Figure 2 is an elevation view of the structure of Figure l;
Figure 3 is an end view of the structure of Figure l;
Figure 4 is a larger scale side view of two solar modules forming part of the dryer of Figures l to 3 and Figùre 5 is a cut-away perspective on a still larger scale taken approximately on the line 5-5 in Figure 4.
Referring first to Figures l to 3, the dryer consists of an assembly lO of a pair of side-by-side, parallel rows ll of serially connected solar modules 12. Air can enter at one end of each of the rows ll through a hood 13, as indicated by the arrow A, to pass along each of the rows ll of modules to be heated. After leaving the last modules the air travels into a converging header l~ which funnels it into a vertical duct 15 from whence it is propelled by a fan 16 into a drying chamber 17, across the top o~ which there extends a perforated tray 18 for supporting the material to be dried, e.g., coffee beans.
It will be noted that the frame members 19 suppor~ the , 2~35 module assembly 10 above the drying chamber 17 so as to act as a roof therefor. As appears from Figure 3, the module assembly is preferably inclined, to provide easy run-off for rain and also to extend at right angles to the average direction of the sun's rays. This direction will, of course, depend upon the latitude at which the dryer is installed. In a typical installation in a country in the tropical latitudes, it is estimated that air entering the hood 13 at 30C will have a temperature of about 60~C when entering the chamber 17. The arrangement is essentially designed as one having a comparatively large volume, high velocity air flow, with only a relatively small temperature rise, e.g. about 30C, since these characteristics are those most suited to the job of efficiently drying such materials as coffee, grain or other foodstuffs.
As shown in Figures 1 and 2, it may be convenient to combine a pair of dryer assemblies 10 in a common structure, but with mainly individual parts. In the arrangement shown in Figures 1 to 3, it is only the duct 15 that is common to the two assemblies.
As best seen in Figure 4, each module 12 consists of two panels 20 and 21. Each panel consists of thermally ~;
insulating side and bottom walls 22 and 23 which define an open-topped channel o~ rectangular cross-section that is transformed lnto a tube 25 by means of a transparent film 24 that extends across the top of the channel. This film ; must, of course, be transparent, or at least translucent, to transmit the solar energy B through to the interior of the tube 25. Convenient material to use for this purpose is a polycarbonate film, typically 4 mils thick, e.g. the film sold by DuPont under the registered trade mark Tedlar~
~: .
~ ~ ~2~35 Inside the tube 25 there is an absorber 26 which consists of an air pervious matrix 27 oF fibrous material supported on a framework 28 of chicken wire or e~uivalent, secured to the side walls 22 by rivets 29. This absorber 26 extends along and across the tube 25, while being inclined in the longitudinal direction, whereby to divide the tube into an upper chamber 30 and a lower chamber 31.
At one end, the tube 25 has an inflow port 32 that communicates only with the upper chamber 30, since the absorber 26 at this end engayes the bottom wall 23. At the other end there is an outflow port 33 that similarly communicates only with the lower chamber 31. As a result, the air, ;ndicated here by the arrows C, is forced to flow through the absorber matrix 27 in its travel along the module Erom inflow to outflow port. The solar energy B
transmitted through the film 24 is absorbed and converted into heat in the absorber matrix 27, such heat then being transferred to the air in its passage therethrough.
The absorber 26 could be inclined in the opposite direction, namely with the inflow port communicating with the lower chamber and the outflow port communicating with the upper chamber. The air would then flow upwardly rather than downwardly through the matrix. However, the arrangement shown in which it flows downwardly is preferred, because this causes the colder incoming air to be in contact with the film 24 through which there can be some heat loss, and the warmer air (after passing through the absorber) to be in the lower chamber which is better insulated.
As a ~urther alternative, the absorber could extend parallel to the bottom wall of the tube with appropriate baffles at each end to direct the air flow. However, the ~ ~ 62735 inclined orientation is preferred, because it distributes the air flow through the absorber more uniformly along the length of the absorber.
As already indicated, it is convenient for each module 12 to be made in two parts, i.e., as separate panels 20 and 21, the panel 20 taking the absorber 26 from the bottom o~ the tube to a position half-way up the tube, while the panel 21 continues the process and takes the absorber to the top of the tube. The panels 20 and 21 are connected at 34 in a manner permitting continuous flow of air. If preferred, each module 12 can be made as a single panel.
The object oE the invention is to provide a dryer of this type having improved efficiency and simplicity, and especially a dryer that is suitable for manufacture, erection and use in small centres or remote areas with limited energy sources.
The heart of the dryer is a new solar module for converting solar energy into heat and transferring such heat to air that is caused to flow through a series of such modules and then over the material to be dried.
More specifically, this module consists of ~a) an open-topped channel deEined by thermally insulating walls, ~b) a translucent film extending across the top of the channel to form a tube having an inflow port and an outflow port at its respective ends, and (c) an absorber comprising an air pervious matrix of fibrous material extending along and across the tube beneath the film to receive solar energy transmitted through such film and to convert such energy into heat, the absorber dividing the tube into an upper chamber and a lower chamber while extending along the tube so that the inflow port communicates only with one of the chambers and the outflow port communicates only with the other of the chambers whereby air travelling between the ports must flow through the absorber to collect heat therefrom.
Preferably, the inflow port communicates with the upper chamber and the outflow port with the lower `~ chamber. Also the absorber is preferably arranged at an inclination to the direction of extent of the tube.
2 ~ 3 5 The invention also relates to the overall assembly of a series arrangement o~ such modules as part of a dryer that also has a system for forcing air along the series of modules and then through the material to be dried.
In its preferred orm, this dryer has the modules arranged as a protective roof over the drying chamber which receives the heated air and has a perforated tray across its top for supporting the material so that the air can pass up through it.
Embodiments of the invention are illustrated by way of example in the accompanying drawings, in which:
Figure l is a plan view of a solar dryer embodying features of the invention;
Figure 2 is an elevation view of the structure of Figure l;
Figure 3 is an end view of the structure of Figure l;
Figure 4 is a larger scale side view of two solar modules forming part of the dryer of Figures l to 3 and Figùre 5 is a cut-away perspective on a still larger scale taken approximately on the line 5-5 in Figure 4.
Referring first to Figures l to 3, the dryer consists of an assembly lO of a pair of side-by-side, parallel rows ll of serially connected solar modules 12. Air can enter at one end of each of the rows ll through a hood 13, as indicated by the arrow A, to pass along each of the rows ll of modules to be heated. After leaving the last modules the air travels into a converging header l~ which funnels it into a vertical duct 15 from whence it is propelled by a fan 16 into a drying chamber 17, across the top o~ which there extends a perforated tray 18 for supporting the material to be dried, e.g., coffee beans.
It will be noted that the frame members 19 suppor~ the , 2~35 module assembly 10 above the drying chamber 17 so as to act as a roof therefor. As appears from Figure 3, the module assembly is preferably inclined, to provide easy run-off for rain and also to extend at right angles to the average direction of the sun's rays. This direction will, of course, depend upon the latitude at which the dryer is installed. In a typical installation in a country in the tropical latitudes, it is estimated that air entering the hood 13 at 30C will have a temperature of about 60~C when entering the chamber 17. The arrangement is essentially designed as one having a comparatively large volume, high velocity air flow, with only a relatively small temperature rise, e.g. about 30C, since these characteristics are those most suited to the job of efficiently drying such materials as coffee, grain or other foodstuffs.
As shown in Figures 1 and 2, it may be convenient to combine a pair of dryer assemblies 10 in a common structure, but with mainly individual parts. In the arrangement shown in Figures 1 to 3, it is only the duct 15 that is common to the two assemblies.
As best seen in Figure 4, each module 12 consists of two panels 20 and 21. Each panel consists of thermally ~;
insulating side and bottom walls 22 and 23 which define an open-topped channel o~ rectangular cross-section that is transformed lnto a tube 25 by means of a transparent film 24 that extends across the top of the channel. This film ; must, of course, be transparent, or at least translucent, to transmit the solar energy B through to the interior of the tube 25. Convenient material to use for this purpose is a polycarbonate film, typically 4 mils thick, e.g. the film sold by DuPont under the registered trade mark Tedlar~
~: .
~ ~ ~2~35 Inside the tube 25 there is an absorber 26 which consists of an air pervious matrix 27 oF fibrous material supported on a framework 28 of chicken wire or e~uivalent, secured to the side walls 22 by rivets 29. This absorber 26 extends along and across the tube 25, while being inclined in the longitudinal direction, whereby to divide the tube into an upper chamber 30 and a lower chamber 31.
At one end, the tube 25 has an inflow port 32 that communicates only with the upper chamber 30, since the absorber 26 at this end engayes the bottom wall 23. At the other end there is an outflow port 33 that similarly communicates only with the lower chamber 31. As a result, the air, ;ndicated here by the arrows C, is forced to flow through the absorber matrix 27 in its travel along the module Erom inflow to outflow port. The solar energy B
transmitted through the film 24 is absorbed and converted into heat in the absorber matrix 27, such heat then being transferred to the air in its passage therethrough.
The absorber 26 could be inclined in the opposite direction, namely with the inflow port communicating with the lower chamber and the outflow port communicating with the upper chamber. The air would then flow upwardly rather than downwardly through the matrix. However, the arrangement shown in which it flows downwardly is preferred, because this causes the colder incoming air to be in contact with the film 24 through which there can be some heat loss, and the warmer air (after passing through the absorber) to be in the lower chamber which is better insulated.
As a ~urther alternative, the absorber could extend parallel to the bottom wall of the tube with appropriate baffles at each end to direct the air flow. However, the ~ ~ 62735 inclined orientation is preferred, because it distributes the air flow through the absorber more uniformly along the length of the absorber.
As already indicated, it is convenient for each module 12 to be made in two parts, i.e., as separate panels 20 and 21, the panel 20 taking the absorber 26 from the bottom o~ the tube to a position half-way up the tube, while the panel 21 continues the process and takes the absorber to the top of the tube. The panels 20 and 21 are connected at 34 in a manner permitting continuous flow of air. If preferred, each module 12 can be made as a single panel.
Claims (6)
1. A solar module for heating air by solar energy, comprising:
(a) an open-topped channel defined by thermally insulating walls, (b) a translucent film extending across the top of the channel to form a tube having an inflow port and an outflow port at its respective ends, and (c) an absorber comprising an air pervious matrix of fibrous material extending along and across the tube beneath the film to receive solar energy transmitted through such film and to convert such energy into heat, the absorber dividing the tube into an upper chamber and a lower chamber while extending along the tube so that the inflow port communicates only with one of the chambers and the outflow port communicates only with the other of the chambers whereby air travelling between the ports must flow through the absorber to collect heat therefrom.
(a) an open-topped channel defined by thermally insulating walls, (b) a translucent film extending across the top of the channel to form a tube having an inflow port and an outflow port at its respective ends, and (c) an absorber comprising an air pervious matrix of fibrous material extending along and across the tube beneath the film to receive solar energy transmitted through such film and to convert such energy into heat, the absorber dividing the tube into an upper chamber and a lower chamber while extending along the tube so that the inflow port communicates only with one of the chambers and the outflow port communicates only with the other of the chambers whereby air travelling between the ports must flow through the absorber to collect heat therefrom.
2. A module according to claim 1, wherein the inflow port communicates with the upper chamber and the outflow port with the lower chamber whereby air passing through the absorber tends to travel in a generally downward direction.
3. A module according to claim 2, wherein the absorber is inclined to the direction of extend of the tube from a location adjacent the bottom of the tube at the inflow port to one adjacent the film at the outflow port.
4. A dryer for particulate solid material, comprising a plurality of modules according to claim 1, 2 or 3, said modules being arranged as a series with the outflow port of a first module connected to the inflow port of a second module and so on, said dryer including (d) means for forcing air along said series of modules from the inflow port of the first module to the outflow port of the last module, and (e) means for passing heated air from the outflow port of the last module through the material to be dried.
5. A dryer for particulate solid material, comprising a plurality of modules according to claim 1, 2 or 3, said modules being arranged as a series with the outflow port of a first module connected to the inflow port of a second module and so on, said dryer including (d) means for forcing air along said series of modules from the inflow port of the first module to the outflow port of the last module, (e) an open-topped drying chamber connected to receive heated air from the outflow port of the last module, and (f) a perforated tray extending across the top of said drying chamber for supporting the material to be dried whereby said heated air can pass upwardly from said chamber through said material.
6. A dryer for particulates solid material comprising a plurality of modules according to claim 1, 2 or 3, said modules being arranged in an assembly consisting of a pair of side-by-side parallel series of modules, with the outflow port of a first module connected to the inflow port of a second module and so on for each series, said dryer including (d) fan means for causing air to flow along each of said series of modules to become heated therein, (e) an open-topped drying chamber connected to receive the thus heated air from the outflow ports of the last module of each series, said chamber having a perforated tray extending across its top for supporting the material to be dried, and (f) frame means supporting said assembly of modules at an elevated location above the drying chamber whereby to form a protective roof therefor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000388880A CA1162735A (en) | 1981-10-27 | 1981-10-27 | Solar dryer and module therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000388880A CA1162735A (en) | 1981-10-27 | 1981-10-27 | Solar dryer and module therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162735A true CA1162735A (en) | 1984-02-28 |
Family
ID=4121276
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000388880A Expired CA1162735A (en) | 1981-10-27 | 1981-10-27 | Solar dryer and module therefor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1162735A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE1008430A4 (en) * | 1994-06-01 | 1996-05-07 | Leon Delvaux | Solar dryer |
| EP1150083A1 (en) * | 2000-04-26 | 2001-10-31 | Karl Kraus | Process and apparatus for drying moist material |
-
1981
- 1981-10-27 CA CA000388880A patent/CA1162735A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE1008430A4 (en) * | 1994-06-01 | 1996-05-07 | Leon Delvaux | Solar dryer |
| EP1150083A1 (en) * | 2000-04-26 | 2001-10-31 | Karl Kraus | Process and apparatus for drying moist material |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |