Solar Heat Collector

Solar heat collector with a pipe in which flows an energetic fluid and a structure consisting of a frame of plastic material with metallic profiles encapsulated during the injection of said plastic material, which allows establishing orifices therein, providing a robust and lightweight collector with few components and dimensionally stable.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The present invention relates to a solar heat collector provided with a pipe (1) inside which flows an energetic fluid. For illustration purposes, a pipe (1) is cited that extends in the collector and is the common situation; however, several pipes (1) can be included that join at the same inlet and outlet as in the case where there is only one pipe (1) or at several inlets and outlets.

The collector comprises an absorbent plate (2) in contact with said pipe (1), normally made of copper or aluminum, with a treatment on its exposed face that enhances solar radiation absorption and reduces emission. This treatment can range from black paint to selective treatments using physical vapor deposition (PVD).

It also comprises an insulation (3) to prevent heat loss arranged in parallel to said absorbent plate (2) and on the side of the pipe (1) opposite to said plate (2), so that it exerts a constant force on said pipe (1).

The structure (4) of the collector is made of a plastic material, such as polyurethane (PU), with a parallelepiped shape which houses the aforementioned elements of the collector, and a transparent cover (5) made of tempered glass, for example, arranged on one of the greater faces of said structure (4) on the side of the absorbent plate (2). In this way, the structure (4) is insulating due to the inherent features of the plastic material and it is not necessary to add further insulation at the location of the plastic structure.

The structure is a frame (4) formed by the four side faces (4.1,4.2,4.3,4.4) of the parallelepiped leaving the greater faces open, formed by injection of plastic material such as by RIM (Reaction Injection Molding), said frame (4) being reinforced by metallic profiles (6) encapsulated in said injection process, so that said profiles (6) have a shorter length than the corresponding plastic sides of the frame (4.1,4.2,4.3,4.4), leaving the corners of the frame with only plastic material and thereby allowing the establishment therein of orifices (7) formed during the injection process of the frame (4).

Optionally and more typically the parallelepiped of the structure (4) is a right parallelepiped, such that the side faces (4.1,4.2,4.3,4.4) of the frame form a right angle to the greater faces.

The profiles (6) have different shapes such that their cross section approximately replicates the shape of the plastic that encapsulates them, in order to compensate the tensions of the plastic during the injection and subsequent stabilization in time. The shape of the metallic profiles (6) is meant to provide structural reinforcement or, in other words, minimize the moment of inertia in the axis perpendicular to the greater surface of the collector.

Thus, the profiles (6) have a rectilinear cross section, such as a constant inverted-Y cross section as shown in the figures, although they could be curved or have any other shape provided the aforementioned requirements are fulfilled.

Said metallic profiles (6) are preferably made of aluminum or galvanized steel, according to tests conducted on them.

The orifices (7) formed during the injection process of the frame (4) are of several types, one of which types is orifices (7.1) for the pipe, which have a greater diameter than said pipe and a circumference that includes a straight segment (7.1.1) at its upper end on which the pipe (1) rests at all times due to the force exerted on it by the insulation (3).

The reason for this configuration is that the pipe (1) expands in a different manner than the structure (4), and that they work at different temperature ranges, so that to prevent loads on the structure (4) the pipe (1) is allowed to expand freely. In addition, an important factor for the efficiency of the collector is a constant distance between the transparent cover (5) and the pipe (1), which is achieved by preventing the deflection of the pipe (1) and the absorbent plate(3) by the aforementioned configuration, which guarantees flatness, as well as with spacers (18) of the cover (5) as stated further below.

In addition, these orifices for the pipe (7.1) comprise a recess (7.1.2) facing out of the collector that is used to house the corresponding sealing gasket(8) and bushing (9), located at the end of the pipe (1).

This configuration seals the collector to prevent entry of rainwater with the sealing gasket (8), which can be fitted to provide a complete seal interfering with the recess or to prevent entry of rainwater while leaving a small air pocket to prevent condensation. This anti-condensation function is regulated and completed by some orifices (7.2) that connect directly to the injection and provide communication between the inside and the outside.

These orifices formed during the frame injection process are attachment orifices (7.3) used to attach some plates (10) on the outside of the orifices for the pipe (7.1) which withstand the pressure exerted on the connections of the pipe (1).

To reinforce the collector assembly, the transparent cover (5) is sealed by an adhesive onto the structure (4), instead of the sealing gasket commonly used. This requires considering that the materials are different and that an elastomeric adhesive is required with a thickness that guarantees its performance in the entire working temperature range.

For this reason, the structure (4) includes walls (4.5) for housing the sealing cord (11) of the transparent cover (5) along the perimeter of said frame (4). Advantageously, the housing walls (4.5) of the sealing cord (11) include separators (4.6) for the transparent cover (5) in the form of protrusions that guarantee the separation between the cover (5) and the frame (4) in the entire range of working temperatures of the collector, providing the dimensional stability needed to optimize the energy efficiency of the collector.

A frame (12) that protects the edge of the transparent cover (5) is placed on said transparent cover (5), preferably made of aluminum, and it is joined to the structure (4) by the same adhesion sealing process used for the cover (5). For this purpose, the frame (4) includes some housing grooves (4.7) in which some tabs (12.1) of the cover edge protection frame (12) are inserted with adhesive, and a sealing cord (13) is applied between said frame (12) and the transparent cover (5).

This adhesion sealing of the transparent cover (5) that makes use of the cover edge protection frame (12) reinforces the collector assembly substantially, making it very robust.

One of the advantages of the injection, as discussed above, is that it allows the plastic to encapsulate other parts or elements by enveloping them. This is also used in the rear closing plate (14), which is attached to the frame (4) by encapsulation along the perimeter with the plastic material of the injection, closing the face of the frame (4) opposite to the transparent cover (5).

Said rear closing plate (14) is meant to support the pressure exerted by wind, acting as a sail that transmits the loads to the perimeter of the frame (4).

In one embodiment, the rear closing plate (14) is made of a plastic material, such as polystyrene (PS), with a smaller modulus of elasticity than the aluminum plate that is normally used. As an alternative or attachment reinforcement, said plate (14) is provided with orifices (17) in the area near its edges and along the same, so that the plastic material of the injection is inserted in said orifices (17) to establish attachments in the form of rivets that encapsulate the plate on the perimeter.

In another embodiment, the rear closing plate is made of a foam plastic material (15), preferably polyurethane or poly-isocyanurate.

Both embodiments of the rear closing plate (14,15) can have their lower greater face or both of their greater face covered with sheets that do not absorb or emit in the infrared band, such that they do not absorb the infrared radiation emitted by the pipe and do not emit infrared to the outside, in this way reducing the losses of the collector.

Some spacers (18) for the cover (5) are placed between the absorbent plate (2) and the transparent cover (5) to guarantee a constant separation between the plate (2) and the cover (5) by opposing the force exerted by the insulation (3).

The frame (4) comprises on the face with the insulation (3), that opposite to the face of the cover (5), some support legs (19) in the form of extensions parallel to the side faces (4.1,4.2,4.3,4.4) of the frame (4).

These legs (19) serve three purposes:acting as guides in the assembly process, as the collectors slide laterally on the profiles of the structure on which they are assembled to be packaged in groups;when the collectors are mounted on a structure in the form of stands, that is with an inclination, the support legs (19) stop the collector from falling due to gravity, securing its attachment to the structure;the top area of the support legs (19) simplifies the task of stacking collectors, as it hold in place the collector stacked on another collector by pressing against the protective frame of the edge of the cover (12).