Concentrating Solar Collector with Trough, Tracking, Receiver Tube system

Abstract

For concentrating solar systems, a trough, tracking system and receiver tube where the trough consists of a frame structure and vertical supports to form a parabolic shape, the trough movement is from the edges using cables (ropes) like a cradle movement, tracking system includes a variable speed cable pulling mechanism to track with sun. The tracking system further includes a controller. The tracking system further includes cables tied to the edges of the trough frame, which are pulled from the center. The tracking system further includes shaft below the trough at the center that winds and unwinds cables like a coil. An actuator and a gear is attached to the shaft structure such that actuator provides a variable and controllable driving force to the tracking mechanism to allow for controlled rotation of each solar collector assembly around its respective longitudinal axis according to sun's position at a given time and location. The receiver tube structure is either double pass (with U turn) or multi-pass (with S-shaped) and covered on top with reflective concentrating shape and with glass at the bottom to provide insulation.

Description

BACKGROUND OF THE INVENTION

Sun is a free source of energy. Man has been developing ways to harness this energy and convert it to more usable form such as heat and electricity. Last few decades, many concentrating devices have been developed to focus and concentrate the electromagnetic radiation on a surface or a line or a point.

Trough systems of various shape (parabolic, elliptical, circular etc) and size (large aperture, small aperture, light weight etc.) and material (glass mirror, aluminum sheets, silver mirror film etc.) have been developed. These systems concentrate sun rays on a receiver tube and covert the solar energy to thermal energy. The troughs have a reflective or a refractive material to redirect the sun rays.

All these systems require the trough to move with the sun in a single axis or dual axes to focus the rays on a receiving surface. Most of these systems use a trough moving and tracking mechanism that moves the trough from the center axis. This mechanism needs a lot of energy to move the troughs. Hence requires heavy duty motors, gears etc. to move the troughs. These systems typically use evacuated tube receiver tubes, which are very costly. The frames to build the trough are also very complicated structures.

Because of the factors above, the initial capital cost as well as subsequent operating costs are high. Hence, cost of energy from sun becomes high and not able to compete with other sources such as fossil fuels.

SUMMARY OF THE INVENTION

Accordingly, object of this invention is to provide a concentrating trough, tracking and receiver tube system, which substantially overcomes a number of the problems encountered in the installation and operation of systems according to prior art.

An object of the present invention is to provide a method for tracking the troughs along sun by moving the troughs from the edges like a cradle using very little auxiliary power, which substantially reduces capital and operating costs.

Another object is to provide a method for making receiver tubes that are easy to fabricate using commercially available material, yet very effective.

A further object of the invention is to provide a method for making the trough and frame structure which involves fewer components and steps to build the assembly in a simpler fashion.

Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the accompanying drawings discloses a preferred embodiment thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Elements in the figures are illustrated for simplicity and clarity and are not drawn to scale. The dimensions of some of the elements may be exaggerated relative to other elements to help improve the understanding of various embodiments of the invention.

The invention will be more fully described in connection with the annexed drawings, where like reference numerals designate like components, in which:

FIG. 1: Trough and Tracking System—Elevation Side View

FIG. 2: Trough and Tracking System—Top View

FIG. 3: Trough and Tracking System—Cross Section View

FIG. 4: Tracking Drive Mechanism—Elevation Side View

FIG. 5: Tracking Drive Mechanism—Top View

FIG. 6: Receiver Tube Assembly—Top View

FIG. 7: Receiver Tube Assembly—Cross Section View

FIG. 8: Multi-Pass Receiver Tube—Top View

FIG. 9: Example 3 Trough Array—Isometric view

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is an elevation side view of a concentrating solar trough collector. The concentrating solar collector is an example of a concentrator. Solar energy collector comprises a reflector 101 with a concentrating shape, which in this case is approximately the shape of a parabolic trough. The parabolic trough shape is a specific example of an approximately constant cross-section shape. The parabolic trough shape is a specific example of a surface with substantial curvature in only one dimension. Reflector 101 is held in place and in shape by trough frame 102 which is an example of a first support means for the reflector 101. By itself, reflector 101 would not be able to maintain its shape since it is thin and flexible. A preferred example of reflector 101 is a aluminum sheet of approximately 1 mm thickness and a silver mirror thin film with thickness under 500 μm. The reflector 101 could also be covered with UV and abrasion protection layers. Solar energy collector also comprises a receiver tube assembly 103 which is an example of a receiving zone. The collector also has supporting columns 104. There is a tracking device 105 assembly that moves the trough as needed. The cables structure 106 that includes two cables on each side of the trough along with edge connecting cables are used to move the trough structure.

FIG. 2 is a top view of a concentrating solar trough collector utilizing the parabolic shaped collector.

FIG. 3 is a cross-section view of a concentrating solar trough collector utilizing a parabolic shaped collector

FIG. 4 is a elevation side view of tracking drive mechanism. It comprises of pulley 401 that are rotated by a shaft 402. The shaft is supported by bearings 403. The shaft is rotated by actuator, gears and controller assembly 404. The actuator could be a stepping motor controlled by controller. The controller is programmed to move the trough based on date, time of day, position of trough, geographic location. The mathematical function that moves the trough is a non linear equation and depends on the size and configuration of the collector assembly. The tracking drive mechanism moves the trough by pulling the cable structure 106.

FIG. 5 is a top view of tracking drive mechanism.

FIG. 6 is a top view of receiver tube assembly. The receiver tube 103 is covered on top by a concentrating shaped reflector 601 (parabolic or circular) to reflect back the rays that may not be focusing on the receiver tube. It is covered at the bottom by a transparent sheet 602 typically made of glass. The whole enclosure is made air tight and thus acts as insulating layer surrounding the receiver tube.

FIG. 7 is a side view of receiver tube assembly.

FIG. 8 is a top of multi-pass receiver tube assembly.

FIG. 9 is an isometric view of a solar energy collector assembly with 3 troughs connected in series.

Other embodiments of the present invention for solar collectors could be for concentrating Solar PV applications. it is important to explicitly state that this concentrating collector can be used for other systems as well such as radio frequency waves, sound waves.

Once given the above disclosure, therefore, various other modifications, features or improvements will become apparent to the skilled artisan. Such other features, modifications, and improvements are thus considered a part of this invention, the scope of which is to be determined by the claims.

Classifications

• U.S. Classification: 126/573, 126/574, 126/575, 126/579, 126/578, 126/602, 126/600, 136/246
• International F24J2/38, F24J2/07, F24J2/46, HO1L31/232 Classification (2013.01)

US Patent References Cited

• U.S. Pat. No. 8,522,772 B1 September 2013 Olsen
• U.S. Pat. No. 8,410,351 B1 April 2013 Gu

Claims

1. A trough, frame structure, tracking and receiver tube system for a concentrating solar collector assembly array, tracking system comprising of cables to move the trough from the sides or edges

2. The tracking system of claim 1 including cables connecting the edges on each side of the moving axis to provide flexible free moving connection.

3. The tracking system of claim 2 including cables to connect the edge connecting cables to a shaft.

4. The tracking system of claim 3 including a shaft to coil and un-coil the cables driven by a stepper motor (actuator).

5. The tracking system of claim 4 including a controller that moves the stepper motor actuator with a non-linear function to keep moving the trough along with sun position calculated based on size of the collector, position of the trough, geographic location, date and time.

6. The trough system of claim 1 built using a frame structure and support bars to provide trough shape desired such as parabolic, elliptical, circular etc.

7. The receiver tube assembly of claim 1 comprising of double-pass tubes with U turn

8. The receiver tube assembly of claim 1 comprising of multi-pass tubes with S-shape.

9. The receiver tube assembly of claim 7 comprising of inverted concentrating trough and flat transparent surface at the bottom which create an insulating enclosure for the receiver tube