SOLAR HEAT COLLECTOR FOR HEATING A CIRCULATING FLUID AND PROCESS FOR MANUFACTURING A SOLAR HEAT COLLECTOR
A solar heat collector is presented for heating a circulating fluid with an inner glass tube and an outer glass tube. The glass tubes are connected at their open ends, and the space between the inner tube and the outer tube being evacuated, wherein the inner space of the inner tube is divided by an insert to define a first channel and a second channel. Said channels are connected at the closed end of the inner tube. The inner glass tube and the outer glass tube have smooth inner and outer surfaces, and the insert is provided such that the first and second channels and a space between the end of the insert and the closed end of the inner tube define the same cross-section.
The invention relates generally to the field of solar thermal energy. In particular, the present invention relates to a solar heat collector with an evacuated glass tube.
BACKGROUND OF THE INVENTIONSolar heat collectors convert the energy of sunlight into thermal heat. Sunlight provides energy in the form of electromagnetic radiation from infrared to ultraviolet. Such solar heat collectors are generally known in the art.
For instance in WO-A-81/00615 an electromagnetic energy collector assembly is described in which a transparent cylindrical glass tube made from common glass tubing lengths is sealed under vacuum at one end to an inner cylindrical energy absorber having a plurality of grooves on the exterior surface. The inner absorber tube may be constructed of glass, metal or other material, and the energy absorbing surfaces have grooves which are helical, or parallel or longitudinal to the normal axis of the absorber. An annular cross-connecting tube extends through the inner absorber tube to a position spaced apart from the closed end of the inner absorber tube. One or more of these energy collectors are detachably connected only through the cross-connecting tube to a manifold system for circulation of a fluid working media as gas or water, which is eventually utilized in any application of thermal energy, e.g. heating, cooling or driving a turbine.
In WO-A-2011/017750 a solar heat generator is described which comprises at least one evacuated glass tube having an internal cavity extending from an open end to a closed end of the tube. An insert is adapted to be positioned within the internal cavity to define at least a first channel and a second channel within the cavity. The first and second channels being adapted such that fluid flowing into the first channel from the open end is directed along the first channel toward the closed end and into the second channel then along the second channel toward the open end.
The solar heat generator of above mentioned reference is described only in very general terms and does not define the necessary details to provide a secure and reliable flow of the fluid through the first and second channels. Moreover, it cannot be derived neither from the description nor from the drawings which dimensions and cross-sections the first and second channel and the open connection between the first and second channel should have.
OBJECT OF THE INVENTIONIt is an object of the present invention to improve the known solar heat collector by allowing a smooth flowing of the fluid through the first and second channels of the glass tube of the heat collector. It is another object of the present invention to provide a manufacturing process for a solar heat collector.
These objects are achieved by a solar heat collector and a manufacturing process with the features described herein. More specifically, a solar heat collector for heating a circulating fluid is provided that includes an inner glass tube having an open end and a closed end, and an outer glass tube having an open end and a closed end, wherein the inner glass tube and the outer glass tube are connected at the open ends of both glass tubes, and a space between the inner glass tube and the outer glass tube is evacuated, wherein the inner space of the inner glass tube is divided by an insert to define a first channel and a second channel within the inner glass tube, the first and second channels being connected at the closed end of the inner glass tube, wherein the inner glass tube and the outer glass tube have smooth inner and outer surfaces, and the insert is provided such that the first and second channels and a space between the end of the insert and the closed end of the inner glass tube define the same cross-section.
A process for manufacturing the disclosed solar heat collector is provided wherein an inner glass tube having an open end and a closed end, and an outer glass tube having an open end and a closed end are produced and connected at the open ends of both glass tubes, such that a space is left between the inner tube and the outer tube, wherein the space is evacuated by means of an evacuation pump, further providing an insert into the inner tube which divide the inner tube in a first channel and a second channel such that the first and second channels and a space between the end of the insert and the closed end of the inner define the same cross-section.
In order to obtain a smooth flowing of the fluid in a solar heat collector it is important that the insert should separate the inner glass tube such that channels with exactly the same cross-section are created and also that the end of the insert is mounted to the glass tube such that the cross-section between the end of the insert and the bottom of the glass tube is commensurate to the cross-section of both channels. Further advantages of the present invention can be derived from the dependent claims and from the following description.
In the following, the invention is described in greater detail, by way of example, with reference to the accompanying drawings. In the Figures there is shown:
The same reference signs are used in each case for the same elements and initial explanations relate to all figures, if not otherwise expressly noted.
In
The inner and outer glass tubes 3 and 6 have a wall thickness of 1-2 mm. The inner glass tube 3 has an inner diameter of 40-45 mm, preferably 43 mm. The outer glass tube 6 has an outer diameter of 60-65 mm, preferably 63 mm. However, the inner diameter can be up to 150 mm and the outer diameter up to 170 mm. The total length of the outer tube 6 is between 150 cm and 180 cm.
The insert 10 can be a thin plate of glass or made of sheet metal. Other materials as synthetic material, ceramics or carbon fibers can be used for producing the insert 10. The insert 10 has a thickness of about 0.5 to 1.0 mm.
In
In
Returning now to
The serrated central part 38 of insert 10B (see
In
In
In
Instead of pinching the insert 10F within the inner glass tube 3, the insert 10F can be manufactured in one piece with the production of the inner glass tube 3.
The solar heat collector as described above is manufactured as follows: the inner glass tube 3 having an open end 4 and a closed end 5 and the outer glass tube 6 having an open end 7 and a closed end 8 are produced and both glass tubes are connected at the open ends 4 and 7, such that a space is left between the inner tube 3 and the outer tube 6. Said space is then evacuated by means of an evacuation pump. Further the insert 10 is provided into the inner tube 1 which divide the inner tube 1 in a first channel 11 and a second channel 12 such that the first and second channels and a space 13 between the end of the insert 10 and the closed end 5 of the inner tube 3 define the same cross-section.
Claims
1. A solar heat collector for heating a circulating fluid with an inner glass tube having an open end and a closed end, and an outer glass tube having an open end and a closed end, wherein the inner glass tube and the outer glass tube are connected at the open ends of both glass tubes, and a space between the inner glass tube and the outer glass tube is evacuated, wherein the inner space of the inner glass tube is divided by an insert to define a first channel and a second channel within the inner glass tube, the first and second channels being connected at the closed end of the inner glass tube, wherein the inner glass tube and the outer glass tube have smooth inner and outer surfaces, and the insert is provided such that the first and second channels and a space between the end of the insert and the closed end of the inner glass tube define the same cross-section.
2. The solar heat collector of claim 1, wherein the insert is a thin plate of glass dividing the inner space of the inner glass tube, such that the first and second channels are identical.
3. The solar heat collector of claim 1, wherein the insert is extruded in one-piece with the inner glass tube.
4. The solar heat collector of claim 1, wherein the insert is a sheet metal dividing the inner space of the inner glass tube, such that the first and second channels are identical.
5. The solar heat collector of claim 2, wherein the insert has on both length sides curved wings having the same curvature as the curvature of the inner glass tube.
6. The solar heat collector of claim 5, wherein the wings are press-fit arranged towards the inner surface of the inner glass tube.
7. The solar heat collector of claim 2, wherein at least one surface of the insert is provided with longitudinal ribs.
8. The solar heat collector of claim 7, wherein the ribs have a triangular shape.
9. The solar heat collector of claim 7, wherein the ribs have a corrugated shape.
10. The solar heat collector of claim 1, wherein the insert has a cross shaped inner part that divides the inner space of the evacuated glass tube into two first channels and two second channels.
11. The solar heat collector of claim 10, wherein the cross shaped inner part comprises an elongated first flat sheet metal part and two identical second flat sheet metal parts that are mounted at right angles along the center lines on both sides of the first sheet metal part, and wherein the widths of the first flat sheet metal part and the two second flat sheet metal parts are commensurate to the inner diameter of the evacuated glass tube.
12. The solar heat collector of claim 1, wherein the insert has a flat central part and bulging edges with rounded rims whereby the insert is pinched towards the inner glass tube of the evacuated glass tube.
13. A process for manufacturing the solar heat collector of claim 1, wherein an inner glass tube having an open end and a closed end, and an outer glass tube having an open end and a closed end are produced and connected at the open ends of the inner glass tube and the outer glass tube, such that a space is left between the inner glass tube and the outer glass tube, wherein said space is evacuated by means of an evacuation pump, further providing an insert into the inner glass tube which divides the inner glass tube into a first channel and a second channel such that the first and second channels and a space between the end of the insert and the closed end of the inner glass tube define the same cross-section.
14. The process according to claim 13, wherein the insert is made of glass and is extruded in one piece with the production of the inner glass tube.
Type: Application
Filed: Jul 17, 2014
Publication Date: Jan 22, 2015
Inventor: Urs FURTER (Sarmenstorf)
Application Number: 14/334,018
International Classification: F24J 2/05 (20060101);