FR2469672A1 - Cylindro-parabolic solar collector - has fixed parabolic reflector formed from insulating material covered in aluminised plastic, with fixed orientation and elevation - Google Patents

Abstract

The collector uses a single curvature parabolic reflector which focuses the sun's rays onto a heat absorbing surface from which energy is drawn. The mirror is fixed, facing southwards with its length running east-west and the angle of elevation is set so maximum conversion efficiency is obtained in mid-winter. This safeguards against overheating during summer. An injection moulded base of a nonflammable material supports an aluminised plastic reflecting sheet which is glued to the insulating base. The collector element is a steel radiator having a height which is sufficient to capture the focussed rays from the Autumn to the Spring equinox. The face of the radiator is coated with a black absorbent paint. The materials chosen allow maximum transmission of the solar spectrum, from 400 to 2,500 microns wavelength, and a minimum transmission for IR radiation re-emitted by the collector.

Description

The present invention relates to a device for capturing solar energy and transforming it into thermal energy by means of a heat transfer fluid.

This device essentially comprises three distinct parts
- the cylindro-parabolic form forming a support and coated with a
reflective mirror.

- a receiving element in which the heat transfer fluid circulates
tor which receives reflected and concentrated solar radiation
by the cylindro-parabolic mirror.

- glazing, located at the top of the recez element
up to the bottom of the dish, ensures the greenhouse effect
as well as the protection of the mirror.

 The space delimited by the parabolic shape, the receiving element and the glazing is closed, at each end, by two insulating and reflecting bases allowing multiple reflections, in particular when the solar radiation is not perpendicular to the mirror.

The cylindro-parabolic form has been studied so that the solar radiation is focused on the receiving element during the period between the equinox of September and the equinox of Mars.

During the summer period, the solar radiation is reflected outside the receiving element so as to avoid any overheating, the greenhouse effect then ensures only the heating of the heat transfer fluid.

The assembly must be placed with a mirror exposed to the SOUTH, the solar radiation being reflected along the "EAST-WEST" axis.

 The cylindro-parabolic form can be obtained by pouring or injecting an insulating and non-flammable product. The side to receive the mirror must be perfectly smooth.

This shape is studied so that it can be placed on level ground without any other support; for this purpose, it extends on the director of the parabola so as to fix the receiving element and to ensure its thermal insulation.

 The mirror is made up either of a high-gloss aluminum foil of high purity, anodized or varnished, or by an aluminized polyester film capable of withstanding temperatures at least equal to 100 ° C., or any other reflecting product.

It must have a high reflectivity to ultraviolet rays, to the visible spectrum and also to near and far in infrared.

 The receiving element is a steel radiator of sufficient height to capture the focused rays from the September equinox to the Mars equinox. The face of the radiator exposed to solar radiation is coated with a matt black absorbent paint.

The glazing can be a single pane, Sécurit glass, an acrylic plate, a polycarbonate plate, altuglass, or any other highly transparent and resistant material.

In all cases, the material chosen must allow a maximum transmission of the solar spectrum from 400 to 2500 and a minimum transmission to infrared re-emitted by the receiving element above 2.500.

The glazing will be installed in a watertight manner to avoid the penetration of water and air.

FIG. 1 represents a section of the panel where 1 constitutes the cylindro-parabolic shape and the support of the receiving element, 2 one of the two feet of each module, 3 the receiving element, 4 the mirror reflecting the solar radiation and infrared, 5 the glazing ensuring the greenhouse effect and the protection of the mirror.

 In this figure, marks A indicate the solar radiation received and reflected on December 22, marks C indicate the solar radiation received and reflected on November 30 and January 30, marks B indicate the solar radiation received and reflected on September 23 and 21 March for a device located on the latitude of 440 NORD at 12 o'clock.

Claims (3)

 1. Device for capturing solar energy and transforming it into thermal energy, consisting of a cylindroparabolic surface receiving the solar radiation and focusing it on a flat radiator in which the heat transfer fluid circulates.  2. Device according to claim 1, characterized in that the assembly is fixed and must not be oriented during the course of the year.  3 Device according to claim 1, characterized in that the receiving element is placed on the director of the parabola.  40 Device according to claim 19 characterized in that no overheating-ntest to fear during the summers the optimum concentration being obtained in winter.  5 Device according to any one of the preceding claims, characterized in that the mirror must be exposed to the South and that the tangent at the bottom of the parabola must be horizontal for a device located at a geographical point of 45 ° North attitude.  6. Device according to any one of the preceding teeth claims, characterized in that the cylindro-parabolic shape, as well as the covering of the radiator must between consist of a non-flammable insulating material. 7. Device according to any one of the preceding claims, characterized in that all of this device combines the advantages of the greenhouse effect and that of the concentration of solar radiation.