Inflatable non-imaging solar concentrator

Abstract

An extremely low cost solar concentrator made of membranes or films is inflated into a Compound Parabolic Concentrator (CPC) a non-image concentrator. The portion of the inflatable concentrator, which is shaped into a CPC concentrator, is formed with reflective membranes or films, and the portions of the inflatable concentrator on the top of CPC and on the bottom of the concentrator are made of clear membranes or films. The incident light including parallel rays of light and diffuse light, as long as falling into the half acceptance angle of the CPC, will be concentrated to the bottom exit aperture of the CPC. Therefore, this type concentrator reduces the requirement to the accuracy of tracking for concentration. In addition, this type of concentrator demonstrates more tolerance to shape distortion for concentration than imaging system.

Claims

1. An inflatable non-imaging Compound Parabolic Concentrator (CPC) solar concentrator comprising: a revolved close structure hollow core shell funnel shaped body having, a CPC portion of the body, a round solar energy entrance aperture of the CPC, a round solar energy exit aperture of the CPC; a domed transparent cover with a round circumference; a flat transparent cover with a round circumference; wherein, the domed transparent cover is covered on the entrance aperture with the circumference of the domed transparent cover overlapped with the circumference of the entrance aperture and connected, the flat transparent cover is covered on the exit aperture with the circumference of the flat transparent cover overlapped with the circumference of the exit aperture and connected, to form a sealed gas chamber with a closed structure which can be made of thin and non-rigid materials without fasten structure but still maintain sufficient mechanical strength to against wind load and keep its geometric shape to concentrate light; wherein, the inner surface of the CPC portion of the revolved close structure hollow core shell funnel shaped body is made reflective to solar radiation by coating a reflective materials reflector; wherein, the transverse profile curves of the CPC portion of the revolved close structure hollow core shell funnel shaped body are two parabolas which form concave reflecting and guiding side surface means; At least one membrane with at least one side coated with reflective materials is tailed and sealed to form the revolved funnel shaped body, at least two transparent membranes are tailed to form the domed transparent cover and the flat transparent cover, and the revolved CPC funnel shaped body and the domed transparent cover and the flat transparent cover are sealed together to form the sealed gas chamber, the sealed gas chamber is inflated into the inflatable non-imaging revolved funnel shaped CPC solar concentrator, rather than the longitudinally-extending trough-shaped CPC, by the gas pressure difference between the inside and environment of the gas chamber; wherein, the outline of the cross section of the gas chamber is not conical but parabolic as the transverse profile curve of CPC non-imaging concentrator.

2. The inflatable non-imaging Compound Parabolic Concentrator (CPC) solar concentrator of claim 1, wherein the wall of the CPC portion of the sealed gas chamber and the solar radiation reflector coated on the inner surface of the CPC portion of the sealed gas chamber are a single entity.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.

(2) FIG. 1 shows the prior art a schematic drawing on construction of the CPC concentrator, which introduces some key concepts such as acceptance half-angle θ.sub.c, focus of each of the parabolas, concentrator aperture, receiver, and axis of parabola.

(3) FIG. 2 is a schematic drawing of the inflatable non-imaging concentrator the assembly of two clear membranes and a reflective membrane inflated into a CPC with a transparent cover on top and a transparent cover on bottom.

DETAILED DESCRIPTION

(4) Reference will now be made in detail to the present exemplary embodiments, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

(5) Referring to FIG. 1, the prior art, a schematic drawing on construction of the CPC concentrator, which introduces some key concepts such as acceptance half-angle θ.sub.c, focus of each of the parabolas, concentrator aperture, receiver, and axis of parabola. The incident light, no matter beam light or diffuse light, as long as falling into the acceptance half-angle θ.sub.c, will be concentrated to the receiver.

(6) Referring to FIG. 2, the CPC 10 made of reflective membrane is covered with a transparent cover 20 on the top and covered with a transparent cover 30 on the bottom to form a sealed assembly with a gas gate on the top transparent cover. Then the assembly is inflated into a shape of CPC covered with clear top and bottom.

(7) If the enclosed apparatus is filled with air and equipped with a solar tracker, the tracking accuracy required for concentration is significantly reduced. When the concentrator is in operation, the incident light penetrating through the top transparent cover 20 will be concentrated by the CPC 10 and output through the bottom transparent cover 30.

(8) If the enclosed apparatus is filled with gases such as helium and hydrogen, it will float in the air and some light tracking system could be employed to concentrate the sunlight.

(9) From the description above, a number of advantages of the solar concentrator become evident. The inflatable apparatus provides an approach to realize an ultra-light, exclusively cheap, extremely compact solar concentrator. The concentrator is able to concentrate both beam and diffuse light. The non-imaging CPC concentrator looses the tracking accuracy required for solar concentration. The inflatable non-imaging balloon type concentrator has higher tolerance to shape distortion than imaging concentrator. The combination of the inflatable non-imaging balloon type concentrator and the photovoltaic receiver or heat exchanger makes super-light and extremely low cost concentrating photovoltaic system or solar thermal system. The close structure of the concentrator enables the filling of the lighter than air helium and hydrogen and floating in the air.

(10) In the preceding specification, various preferred embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various other modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.

(11) Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.