Stoves and furnaces – Solar heat collector – With means to convey fluent medium through collector
Reexamination Certificate
2003-07-07
2004-11-16
Basichas, Alfred (Department: 3749)
Stoves and furnaces
Solar heat collector
With means to convey fluent medium through collector
C126S651000
Reexamination Certificate
active
06817357
ABSTRACT:
The invention relates to a tubular collector module with a header tube, with has an inlet and an outlet for the heat transfer medium, and having at least one collector tube, through which the flow is coaxial, and which has an envelope tube, an absorber tube, and a coaxial tube.
The collector tubes through which the flow is coaxial belong to the category of collector tubes with an absorber through which the flow is direct. These collector tubes have an envelope tube, an absorber tube, and a coaxial tube. These three tubes are disposed inside one another, with the envelope tube located outermost, the absorber tube located eccentrically or coaxially to the envelope tube, and the coaxial tube located coaxially to the absorber tube. The envelope tube and the absorber tube are sealed off from one another. In the interstice between the envelope tube and the absorber tube, there is either a vacuum or an inert gas. This serves above all to insulate the absorber tube from the environment. The absorber tube is coated with an absorber in order to absorb the solar heat. To transport this heat onward, a heat transfer medium flows through the absorber. In collector tubes in which the flow is coaxial, the heat transfer medium is introduced through a coaxial tube. This is a tube open on both ends, which enters the absorber tube through one of its two ends. The other end of the absorber tube is closed. The end of the coaxial tube that does not protrude into the absorber tube communicates with the inlet of the header tube. The heat transfer medium flows through the inlet into the coaxial tube and from there through the absorber tube and back again to the outlet. From the outlet of the header tube, the heat transfer medium is carried to a heat exchanger, where it gives up the heat to the reservoir.
Various tubular collectors through which the flow is coaxial are available on the market. One widely distributed tubular collector has separate lines for the inlet and outlet of the header tube. Flexible corrugated tubes are used as the inlet and outlet. The absorber tube and the coaxial tube are joined to the inlets and outlets via clamping ring screw fastenings. This type of assembly is very complicated and relatively expensive. The use of separate lines for the inlet and outlet also means increased space is required. Furthermore, if flexible corrugated tubes are used, a housing for the header system must also be provided.
The tubular collectors described above are as a rule constructed as modules comprising a plurality of collector tubes all connected to a common inlet and a common outlet. The individual tubular collector modules can be combined with one another via double O-ring plug-in connections.
In another tubular collector with a flow coaxially through it that is available on the market, the header tube also experiences a coaxial flow through it. Both the absorber tube and the coaxial tube, as well as the outer coaxial tube of the header tube, are embodied integrally as a whole. This does have the advantage that only the envelope tube has to be sealed off from the absorber tube. However, the production of these tubular collectors is very complicated.
A further tubular collector with a flow coaxially through it is described in German Utility Model DE 298 08 532 U1. The header tube in that reference is embodied as a header box assembly. The inlet and the outlet are described as two integrally embodied conduits extending parallel, which are separated only by a wall that has the applicable opening for the various coaxial tubes. The coaxial tube is inserted into the openings in the partition, and the absorber tube is received by an opening in the side wall of the header box, which wall communicates with the outlet conduit, and the envelope tube is received in an extension of the housing. All three tubes are joined by adhesive to the housing parts or header box parts. As a result, it is true that a more-compact design is achieved. However, the seal that is attainable by the adhesive has proved to be inadequate under a high thermal load.
German Utility Model 299 08 190 U1 describes a special clamping system for solar collectors. The vacuum tubes and the tubes of the heat transfer circulation system intersect, touching one another for heat transfer, at an angle of 90°; the intersecting tubes are joined to one another by positive engagement by means of a clamping system, comprising two jaws whose clamping jaws can be prestressed by a tensing mechanism.
German Utility Model DE 297 10 494 U1 discloses a solar collector with a heat pipe, which transfers the heat by evaporation and condensation of a heat-carrying liquid. To avoid overheating, a closure device of bimetal is provided, which if a threshold temperature is exceeded restricts the flow of the heat-carrying liquid from the condenser to the evaporator.
German Patent Disclosure DE 32 06 624 A1 involves a solar energy collector based on an air/water heat exchanger, in which a plurality of collector elements are connected together fluidically. To improve the air circulation, a blower is provided.
International Patent Disclosure WO 83/3891 discloses a tubular solar collector without coaxial tubes in the absorber tubes, which are inclined downward relative to a header tube. The absorber tubes are sealed off from the header tube by means of O-rings.
With this background, it is the object of the present invention to furnish a tubular collector module which intrinsically combines the advantages of simple assembly and good sealing.
This object is attained by a tubular collector module as defined by claim
1
.
The tubular collector module of the invention can be assembled very simply. If the coaxial tube is not joined solidly to the absorber tube and to the envelope tube, then the coaxial tube is first introduced through the nipple into the receiving element of the inlet. Next, an elastic element is introduced into the absorber tube, into the end remote from the header system. The absorber tube is then inserted via the coaxial tube and via the nipple of the header system.
By means of the sealing element between the nipple and the absorber tube, no heat transfer medium can escape between the nipple and the absorber tube. The elastic element that is disposed in the absorber tube in turn presses the coaxial tube into the receiving element of the inlet. The heat transfer medium can now flow from the inlet into the coaxial tube, into the absorber tube on the opposite end of the coaxial tube, and back again between the nipple and the coaxial tube into the outlet.
If the collector tube is not joined to the absorber tube, then it is inverted over the absorber tube afterward; if the absorber tube and the collector tube are solidly joined to one another, then the absorber and the collector tube are simultaneously inverted over the coaxial tube and the nipple.
To enable assuring an unimpeded flow of the heat transfer medium even if the elastic element provides strong sealing, the elastic element is advantageously embodied as a spiral spring.
The sealing element is advantageously embodied between the nipple and the absorber tube as at least one O-ring. Thus not only is the best sealing achieved, but O-rings are also economical and simple to install. Moreover, by the selection of a suitable plastic, it is possible to optimize the service life, despite the thermal load during continuous operation.
Advantageously, the at least absorber tube and the at least one envelope tube are embodied integrally. This has the advantage that the vacuum or the inert gas atmosphere that prevails between the absorber tube and the envelope tube, for the sake of achieving good functioning of the solar collector, is not later impaired, for instance by leaks where the absorber tube is joined to the envelope tube.
The collector tube is the envelope tube that is permeable to sunlight. It comprises a transparent material. This is indeed generally a material of low thermal conductivity, but this property is not decisive, since the tube is intended not to heat up severely. Preferably, the envelope
Brunotte Martin
Haas Gottfried
Quast Klaus
Basichas Alfred
Schott Glas
Striker Michael J.
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