WO2003033971A2

WO2003033971A2 - Solar heat collector

Info

Publication number: WO2003033971A2
Application number: PCT/ZA2002/000159
Authority: WO
Inventors: Nicholas Ivanovic
Original assignee: Nicholas Ivanovic
Priority date: 2001-10-15
Filing date: 2002-10-15
Publication date: 2003-04-24
Also published as: WO2003033971B1; WO2003033971A3

Abstract

A solar heat collector (10) includes a closed container (12) for enclosing collector tubing (14) in a space, the container (12) having a transparent window (16) for receiving solar radiation (18) into the container (12) and a reflective support surface (20), opposite to the transparent window (16), for supporting collector tubing (14), and an array of collector tubing, the tubes (22) of the tubing (14) being generally arranged in parallel and spaced apart from another on the surface such that, in use, when solar radiation enters the container with an incidence angle of the component perpendicular to the tubing being between 0° and 70°, the radiation radiates the tubes and at least a portion of the reflective support surface between the tubes.

Description

TITLE: SOLAR HEAT COLLECTOR

Technical field of the invention

THIS INVENTION relates to a solar energy collection device. More particularly, the invention relates to a solar heat collector and a reservoir for a solar heat collector.

Background to the invention

Generally, known solar heat collectors include a fluid filled circuit comprising an array of collector tubes and an insulated reservoir, which is in fluid communication with the collector tubes, and an enclosed tray for enclosing the collector tubes in a gas filled space, the enclosed tray having a transparent sheet for receiving solar radiation into the enclosed tray.

The applicant is aware that, due to its high conductivity, certain solar heat collectors use metal collector tubes. These tubes are normally arranged in conductive material having a solar heat absorbing surface, or arranged to absorb solar heat directly on its surface, the tubes being spaced in close proximity to each other to increase the area of the absorbing surface. Although the metal tubing conducts heat effectively, such a collector usually employs separate fluid circuits to prevent the metal tubes from bursting during temperatures below the freezing point of the fluid. These collectors use a fluid with a low freezing point in a fluid circuit, which include the collector tubes and a heat exchanger in contact with a second fluid circuit, such as a household water circuit. It will be appreciated that these heat collectors are complicated and expensive to manufacture.

Generally, due to the high temperature of the fluid, in use, the insulated reservoir of a solar heat collector is a pressure vessel. The cost of known pressure vessels adds to the relative high manufacturing costs of solar heat collectors. The effectiveness of solar heat collectors depends on its design, and generally the more effective the collector, the more expensive its manufacturing costs. It is an aim of the applicant to provide an effective yet low cost solar heat collection device.

General description of the invention

A first aspect of the invention provides a solar heat collector, which includes: a closed container for enclosing collector tubing in a space, the container having a transparent window for receiving solar radiation into the container and a reflective support surface, opposite to the transparent window, for supporting collector tubing; and an array of collector tubing, the tubes of the tubing being generally arranged in parallel and spaced apart from another on the surface such that, in use, when solar radiation enters the container with an incidence angle of the component perpendicular to the tubing being between 0° and 70°, preferably between 0° and 60°, the radiation radiates the tubes and at least a portion of the reflective support surface between the tubes.

It will be appreciated that, in use, the sun radiates the sun facing side of the tubes and the reflective support surface, the reflected and/ or scattered radiation, in turn, radiates the side of the tubes in the shade.

The transparent window may be a transparent sheet of glass, plastic material or the like.

The reflective support surface may be a diffuse reflective surface. The reflective surface may be provided by a sheet of material having, or being covered with a material having, a light reflectivity of about 80 as measured using the CIE (The International Commission on Illumination) system and an Hluminant D 10°.

The tubes of the colleector tubing m(.- may be circular in cross section and may be generally equidistantly spaced from each other, the distance being area of tubing pβfcinit volume of fluid in the tubing being rWβfaled and heated half to one and a half of the diameter of the tubes, preferably equal to the diameter of the tubes.

The tubes of the collector tubing may be arranged in a series of generally planar-parallel spaced tubes of equal length and the collector may further include a pair of combining conduits for combining the ends, in fluid communication, of the tubes at respective opposed ends of the series of collector tubes.

The applicant has found that this arrangement allows for a mmaximum

respectively.

The container may further include an insulating layer between the support surface and a corresponding opposed outer wall, other than the transparent sheet, of the container to prevent excessive loss of heat absorbed, in use, by the support surface.

It will be appreciated that the solar heat is absorbed directly by the tubing on its surface and does not rely on the conductivity of another solar heat absorbing surface, which, in turn, conducts its heat to the tubing. The tubing may therefore be dark coloured to enhance solar heat absorbance.

The tubes of the collector tubing may be manufactured from an expandable plastics material such as, for example, polyvinyl chloride, High Density Polyethylene and the like. It will be appreciated that expandable plastic tubes will expand to accommodate expanded frozen liquids such as ice. The tubes of this type of tubing are resistant to corrosion and degradation, can readily be joined, and is readily available on the market at a relatively low cost compared to metal tubing.

The collector may include a reservoir in fluid communication with the collector tubing. One of the pair of combining conduits may lead into the reservoir and the other combining conduit may lead out of the reservoir thereby defining a fluid flow circuit. It will be appreciated that, in use, thermal siphon may cause the fluid to flow in the circuit. The reservoir may be insulated.

Instead, the tubing may be connectable in fluid communication, to a fluid flow circuit, the circuit including a reservoir such as a swimming pool. The fluid flow circuit may then include a filter pump of a swimming pool for circulating the fluid, water, through the fluid flow circuit.

The collector may include a support member for supporting the container in an orientation such that the reflective support surface and each collector tube is transverse to a plane defined by an average seasonal path of the sun across the sky from East to West due to the rotation of the earth.

The collector may include a housing for housing the reservoir. The support member for supporting the container in said orientation may be part of the housing, such as a wall of the housing. Thus, in one embodiment, the wall of the housing and the outer wall of the container may abut at edges thereof and may be angled at a predetermined angle relative to each other such that the wall of the housing defines the support member, which, in use, supports the container in an orientation such that the reflective support surface and each collector tube is transverse to a plane defined by an average seasonal path of the sun across the sky from East to West due to the rotation of the earth. It will be appreciated that the angle will depend on the pitch of a surface whereon the collector is to be mounted such as a roof of a house and the latitude of the location where the collector is to be used.

According to a second aspect of the invention, there is provided a reservoir for a solar heat collector, the reservoir including: a pipe of a polymeric material; a first closure configured to seal one end of the pipe; a second closure configured to seal the other end of pipe; an inlet and outlet leading into and out of the reservoir, the inlet and outlet being connectable to solar heat collector tubing; and an inlet and outlet leading into and out of the reservoir, respectively for charging and draining the reservoir.

The polymeric material may be a plastics material.

The pipe may be fibre re-inforced.

The applicant has found that when a fluid such as water is heated to 60°C, in a solar heat collector, the pressure in the reservoir can rise to approximately 400kPa. 400kPa corresponds to the average pressure in household plumbing systems.

The reservoir may include a clamping system for clamping the first and second closures into its respective closing positions such that it the reservoir can withstand a hydrostatic pressure of at least 400kPa.

In the case of the reservoir including a plastic pipe, the clamping system may comprise a pair of frames, one frame configured to locate the first closure and the other configured to locate the second closure, and a means for urging the frames towards each other such that each closure sealingly closes the reservoir. The means for urging the frames toward each other may be two or more strips along the length of the pipe, each end of each strip being configured to be fastened to a respective frame.

Detailed description of the invention

The invention is now described, by way of example, with reference to the accompanying drawings.

In the drawings,

Figure 1 shows schematically a three dimensional view of a solar heat collector, in accordance with the invention;

Figure 2 shows schematically a sectional side view through A-A of the solar heat collector; Figure 3 shows schematically a portion of a sectional end view through B-B of the solar heat collector;

Figure 4 shows schematically an end view of collector tubing, in accordance with the invention;

Figure 5 shows schematically a three dimensional view of a reservoir, in accordance with the invention; and

Figure 6 shows schematically a sectional side view of the reservoir.

In the drawings, reference numeral 10 generally indicates a solar heat collector, in accordance with the invention.

The solar heat collector 10 includes a closed container 12 for enclosing an array of collector tubing 14 in an air filled space. The container 12 has a transparent sheet 16 for receiving solar radiation, indicated by the arrows marked 18, into the container 12. The container 12 further includes a reflective support surface 20, opposite to the transparent sheet 16, for supporting the array of collector tubing 14. The tubes 22 of the array 14 are manufactured from black, highly plasticized polyvinyl chloride, which are circular in cross section and are generally equidistantly spaced from each other, the distance between adjacent tubes 22 being equal to the diameter of the tubes 22. The array 14 is arranged in a series of generally planar-parallel spaced tubes 22 such that, in use, when solar radiation enters the container 12 with an incidence angle of the component perpendicular to the array 14 being between 0° and 60°, the radiation radiates the tubes 22 and a portion of the reflective support surface 20 between the tubes 22. Therefore, in use, the collector 10 is positioned and orientated on an outdoor surface such as a roof of a house such that, for most of a day, the sun radiates the sun facing side of the tubes 22 and the reflective support surface 20, the reflected and/ or scattered radiation indicated by the arrows marked 19, in turn, radiates the side of the tubes 22 in the shade.

The reflective support surface 20 is a diffuse reflective surface. The reflective surface is provided by a sheet of material having a light reflectivity of about 80 as measured using the CIE (The International Commission on Illumination) system and an illuminant D10*.

The array 14 is arranged in a series of collector tubes 22 of equal length and the collector 10 further includes a pair of combining conduits 24 for combining the ends, in fluid communication, of the tubes 22 at respective opposed ends of the series of collector tubes 22.

The collector tubes 22 and combining conduits 24 and all other components which are water filled and not high pressure components are manufactured from expandable plastic.

The container 12 further includes an insulating layer 26 between the support surface 20 and a corresponding opposed outer wall 28 of the container 12 to prevent excessive loss of heat absorbed, in use, by the support surface 20.

The collector 10 further includes a reservoir 30 in fluid communication with the collector tubing 14. One of the pair of combining conduits 24.1 leads into the reservoir 30 and the other combining conduit 24.2 leads out of the reservoir 30 thereby defining a fluid flow circuit. In use, thermal siphon cause the fluid, water, to flow in the circuit. The reservoir 30 is provided with a layer of insulation 32 and the reservoir 30 connected, in use, for example, with a household water system (not shown).

The collector 10 includes a support member 34 for supporting the container 12 in an orientation such that the reflective support surface 20 and each collector tube 22 is transverse to a plane defined by an average seasonal path of the sun across the sky from East to West due to the rotation of the earth.

The collector 10 includes a housing 36 for housing the reservoir 30. The support member 34 for supporting the container 12 in said orientation may be part of the housing 36, such as a wall 38 of the housing 36. Thus, in this embodiment of the invention, the wall 38 of the housing 36 and the outer wall 28 of the container 12 abut at edges 40 thereof and is angled at a predetermined angle θ relative to each other such that the wall 38 of the housing supports, in use, the container 12 in an orientation such that the reflective support surface 20 and each collector tube 22 is transverse to a plane defined by an average seasonal path of the sun across the sky from East to West due to the rotation of the earth. It will be appreciated that the angle will depend on the pitch of a surface whereon the collector is to be mounted such as a roof of a house and the latitude of the location where the collector is to be used. The outer wall 28 of the container 12 is at an angle θ to the support member 34. The support member 34 has a flat surface and the collector 10 is to be mounted on a roof such that the flat surface of the support member 34 is horizontal. The angle θ is equal to 90° plus the average solar altitude angle at a solar azimuth of 0° for the latitude in which the collector 10 is to be mounted. For example, the average solar altitude angle for South Africa situated at a latitude of 25° south of the equator is 64.5° at a solar azimuth of 0° for 12 months of the year. In this case θ equals 90° plus 64.5°, which equals 154.5°.

Referring now to figures 5 and 6. The reservoir 30 includes a plastic pipe 42, a first closure 44 configured to seal one end 46 of the pipe 42, a second closure 48 configured to seal the other end 50 of pipe 42. The reservoir 30 further includes an inlet and outlet (not shown) leading into and out of the reservoir 30, the inlet and outlet being connectable to collector tubing and an inlet and outlet (not shown) leading into and out of the reservoir 30 for charging and draining the reservoir 30. The first mentioned inlet and outlet is connected to the conduits 24.1 and 24 .2 respectively.

The reservoir 30 further includes a clamping system 52 for clamping the first and second closures 44 and 48 into its respective closing positions such that it the reservoir 30 can withstand a hydrostatic pressure of at least 400kPa.

The clamping system 54 comprises a pair of frames 54, one frame 54.1 configured to locate the first closure 44 and the other 54.2 configured to locate the second closure 48, and three strips 56 along the length of the pipe 42, each end of each strip 56 being configured to be fastened to a respective frame 54.1 or 54.2.

The applicant believes that the invention provides an effective yet low cost solar heat collector.

It shall be understood that the example is provided for illustrating the invention further and to assist a person skilled in the art with understanding the invention and are not meant to be construed as unduly limiting the reasonable scope of the invention.

Claims

Claims:

1. A solar heat collector, which includes: a closed container for enclosing collector tubing in a space, the container having a transparent window for receiving solar radiation into the container and a reflective support surface, opposite to the transparent window, for supporting collector tubing; and an array of collector tubing, the tubes of the tubing being generally arranged in parallel and spaced apart from another on the surface such that, in use, when solar radiation enters the container with an incidence angle of the component perpendicular to the tubing being between 0° and 70°, the radiation radiates the tubes and at least a portion of the reflective support surface between the tubes.

2. A solar heat collector as claimed in Claim 1 , wherein the tubes of the tubing are generally arranged in parallel and spaced apart from another on the surface such that, in use, when solar radiation enters the container with an incidence angle of the component perpendicular to the tubing being between 0° and 60°, the radiation radiates the tubes and at least a portion of the reflective support surface between the tubes.

3. A solar heat collector as claimed in Claim 1 or Claim 2, wherein the reflective support surface is a diffuse reflective surface.

4. A solar heat collector as claimed in Claim 3, wherein the reflective surface has a light reflectivity of about 80 as measured using the CIE (The International Commission on Illumination) system and an illuminant D 10°.

5. A solar heat collector as claimed in any one of the previous claims, wherein the tubes of the collector tubing are circular in cross section and generally equidistantly spaced from each other, the distance being half to one and a half of the diameter of the tubes.

6. A solar heat collector as claimed in Claim 5, wherein the distance is equal to the diameter of the tubes.

7. A solar heat collector as claimed in any one of the previous claims, wherein the tubes of the collector tubing are arranged in a series of generally planar-parallel spaced tubes of equal length and the collector further includes a pair of combining conduits for combining the ends, in fluid communication, of the tubes at respective opposed ends of the series of collector tubes.

8. A solar heat collector as claimed in Claim 7, wherein the container includes an insulating layer between the support surface and a corresponding opposed outer wall, other than the transparent sheet.

9. A solar heat collector as claimed in Claim 7 or Claim 8 , wherein the tubes of the collector tubing and the combining conduits are manufactured from an expandable plastics material.

10. A solar heat collector as claimed in any one of the claims 7 to 9, which includes a reservoir in fluid communication with the collector tubing.

11. A solar heat collector as claimed in Claim 10 wherein one of the pair of combining conduits lead into the reservoir and the other combining conduit lead out of the reservoir to define a fluid flow circuit.

12. A solar heat collector as claimed in any one of the previous claims, which includes a support member for supporting the container in an orientation such that the reflective support surface and each collector tube is transverse to a plane defined by an average seasonal path of the sun across the sky from East to West due to the rotation of the earth.

13. A solar heat collector as claimed in Claim 12, which includes a housing for housing the reservoir, the housing forming the support member for supporting the container in said orientation.

14. A solar heat collector as claimed in any one of claims 10 to 13, wherein the reservoir includes: a pipe of a polymeric material; a first closure configured to seal one end of the pipe; a second closure configured to seal the other end of pipe; an inlet and outlet leading into and out of the reservoir, the inlet and outlet being connectable to solar heat collector tubing; and an inlet and outlet leading into and out of the reservoir, respectively for charging and draining the reservoir.

15. A solar heat collector as claimed in Claim 14, wherein the polymeric material is selected from a plastics material.

16. A solar heat collector as claimed in any one of claims 10 to 13, wherein the reservoir is manufactured from a fibre re-enforced polymeric material.

17. A solar heat collector as claimed in any one of claims 14 to 15, wherein the reservoir includes a clamping system for clamping the first and second closures into its respective closing positions such that it the reservoir can withstand a hydrostatic pressure of at least 400kPa.

18. A solar heat collector as claimed in Claim 17, wherein the clamping system comprises a pair of frames, one frame configured to locate the first closure and the other configured to locate the second closure, and a means for urging the frames towards each other such that the each closure sealingly closes the reservoir.

19. A solar heat collector as claimed in Claim 18, wherein the means for urging the frames toward each other is two or more strips along the length of the pipe, each end of each strip being configured to be fastened to a respective frame.

20. A solar heat collector as claimed in any one of claims 17 to 19, wherein the inlets and outlets are manufactured from an expandable plastics material.

21. A solar heat collector substantially as described herein with reference to the accompanying drawings.