WO2011134759A2

WO2011134759A2 - A solar trough system

Info

Publication number: WO2011134759A2
Application number: PCT/EP2011/055292
Authority: WO
Inventors: Rahmi Oguz Capan
Original assignee: Rahmi Oguz Capan
Priority date: 2010-04-26
Filing date: 2011-04-05
Publication date: 2011-11-03
Also published as: WO2011134759A3

Abstract

The solar trough system (A) of the invention comprises at least one trough - shaped reflective surface (1) that directs sunlight to its focus (F) and rotates about its focus (F) which is its own rotation axis; at least one thermal receiver member (2) provided on focus (F) of the surface (1) and extending along the reflector (1). In said system, center of gravity (3) of movable parts is provided on the focus (F) of reflector (1) in any possible angle of repose of the reflector (1).

Description

DESCRIPTION

A SOLAR TROUGH SYSTEM

Technical Field

This invention relates to solar trough systems which concentrate the sunlight on a focus and produce energy.

Prior Art

Currently, solar trough systems are used to collect the sun's energy in order to obtain electricity and heat therefrom. These systems comprise trough-shaped long parabolic reflectors, thermal receiver members which are placed on the focus of the reflectors where beams coming from the reflector are collected, and a rotating mechanism which aligns the reflectors to the position the sun is present. The beams coming to the reflectors which are directed towards the sun are reflected and collected on the thermal receiver member located on the focus of the reflector. Thermal receiver member is provided with two nested tubes where a vacuum environment is located in the space therebetween. A fluid, which ensures heat transfer, passes through the inner tube. The outer tube is made of glass. By concentrating the beams coming from the reflectors on the thermal receiver tube, this tube reaches very high temperatures; therefore, the fluid located in the inner tube can be heated. Heat energy can be converted into the electric energy, when desired, by means of this fluid which reaches high temperatures.

In systems disclosed in published patent applications no. US4559926 and US4432343, trough-shaped parabolic reflectors reflect sunlight to the receiver tube and ensure that the fluid in the tube is heated. In these systems, receiver tube is kept fixed and it is provided on focus of parabolic reflectors. Under the parabolic reflectors, there are provided circular support parts which splice two ends thereof; center of said support parts coincides with focus of reflectors. Circular support parts are rotated in centerlines thereof in order to ensure that the systems track the sun, and thus, the parabolic reflectors rotate around of immovable receiver tube provided on focus thereof. In these systems, since the receiver tubes are kept immovable, there is no need for using a movable fluid connection member resistant to high pressure and temperature while connecting the parabolic troughs to main line by means of conventional pipe line. However, in these systems, position of center of gravity of movable parts changes steadily. Therefore, much energy is consumed in order to rotate the systems. Moreover, since center of gravity of the systems changes, variant torsion forces exerted on the systems have negative effects on performance of the systems.

Brief Disclosure of Invention

Solar trough system of the invention comprises at least one trough-shaped reflective surface directing sunlight to its focus and rotating about its own focus, which is its own rotation axis; at least one thermal receiver member provided on focus of the surface and extending along the reflector. In said system, center of gravity of movable parts is at the focus of reflector in every angle of repose of the reflector. Thus, at least one counterweight, which moves center of gravity of movable parts of the system to focus of the reflector, is used. For the aim of keeping counterweight in desired position, at least one retaining profile is used. Center of gravity of movable parts of the system is kept immovable by means of counterweight used in solar trough systems of the invention and then, energy required for operating the system is saved (in comparison with old system). Moreover, the torsion forces on the system are minimized and supports for grounding to floor can be decreased. In addition, this situation causes a reduction in weight of movable parts and helps reduce the energy required for operating the system.

Objective of Invention

An aim of the invention is to form a solar trough system, which can rotate about thermal receiver member with fixed axis on its own focus and which has trough- shaped reflector.

Another aim of the invention is to ensure that center of gravity of movable parts is kept immovable in said solar trough system. A further aim of the invention is to ensure that said center of gravity coincides with axis of thermal receiver member.

Still a further aim of the invention is to ensure that less energy is consumed in comparison with the prior art in order to rotate movable parts and reduce weight of the system by means of above mentioned structure.

Yet a further aim of the invention is to form a reliable solar trough system which is easy and cheap to produce and use.

Description of Figures

An exemplary solar trough system of the invention is illustrated in figures, wherein;

Figure 1 is side view of a position of a solar trough system of the prior art.

Figure 2 is side view of another position of a solar trough system of the prior art.

Figure 3 is side view of a position of a solar trough system of the present invention.

Figure 4 is side view of another position of a solar trough system of the present invention.

All the parts illustrated in figures are individually assigned a reference numeral and the corresponding terms of these numbers are listed as below.

Solar trough system (Α') (of the prior art)

Solar trough system (A)

Reflective surface (1 )

Thermal receiver member (2)

Center of gravity (3) Counterweight (4)

Loop (5)

Fixed supports (6)

Connection profile (7)

Support profile (8)

Retaining profile (9)

Arc (10)

Focal point (1 1 )

Focus (F)

Line (L)

Disclosure of Invention

Side views of a solar trough system (Α') of prior art are illustrated in Figures 1 and 2 regarding different angles of repose. In said system (Α'), there is provided at least one reflective surface (1 ) directing sunlight to its focus (F). The surface (1 ) is trough- shaped (preferably having a parabolic geometry) and has feature of rotating about its own focus (F). There is provided at least one thermal receiver member (2) (which is concentric with the focus (F) and extends along the reflector (1 )) in focus (F) of the surface (1 ). (As an example for most common utilization, thermal receiver member (2) comprises two nested tubes between which a vacuum space is provided. A fluid, which provides the heat transfer, is passed through the inner tube called transfer tube having high heat conductivity. The transparent outer tube (preferably made from glass) ensures that beams coming from the reflector reach to transfer tube directly. Therefore, the temperature of the transfer tube and fluid therein is increased. Vacuum space is created between the transfer tube and lucid tube in order to prevent conventional heat loss from the transfer tube to outside.)

By establishing the system in direction of north-south and the reflective surface (1 ) is directed to sun (by rotating in the direction of east-west) all day long, beams coming from the sun hit the reflective surface (1 ) and they are concentrated on the thermal receiver member (2), and thus heat energy is produced. (In an exemplary embodiment, above mentioned member (2) makes fluid passing there through reach very high temperatures. By taking advantage of fluid at high temperature, the heat energy can be converted into other energy forms (motion energy, electricity etc.)

As known, solar trough systems (Α') are constructed in many meters long in order to obtain desired amount of energy from said systems (Α'). Therefore, the reflective surfaces (1 ) are exposed to wind load and also they can even become deformed due to their own weights. There are formed various structures supporting the surfaces (1 ) from their under sides in order to prevent deformation of surfaces (1 ) and protect their durability.

One loop (5) and connection profiles (7) are illustrated in Figures 1 -2 as example for these structures. Since the loop (5) and the connection profiles (7) (these profiles (7) connect the loop (5) and the surface (1 ) to each other) support the reflective surface (1 ) from beneath, they are to move by rotating together with the surface (1 ). By taking advantage of circular form of the loop (5), the reflective surface (1 ) is rotated (here, center of loop (5) is also focus (F) of the surface (1 )) by sliding the loop (5) on the fixed supports (6) (these supports (6) can be in roller form).

Moreover, support profiles (8), which prevent deformation of thermal receiver member (2) and support said member (2) from beneath are also used. These profiles (8) are connected to said member (2) from its one end (by bearings or swing bearings) and centerline (the focus (F)) of the member (2) rotates together with movable parts of the system (Α').

However, center of gravity (3) of movable parts of the solar trough system (Α') in said figure always remains between thermal receiver member (2) and the reflective surface (1 ). Due to rotation of reflective surface (1 ), this center of gravity (3) moves steadily. For example, as shown in Figures 1 -2, the center of gravity (3) is to move in arc (10) form (archly). Therefore, energy required for operation of the system (Α') increases (especially on start and end of the motion). Moreover, due to changing moment values, the system (Α') is to be strengthen and thus, both weight and cost of the system (Α') (if the system is not rigid enough, lost in performance can be experienced due to torsion movement) increases. Therefore, it is important that the center of gravity (3) of movable parts of the system (Α') does not change.

In figures 3-4, side views of one solar trough system (A) of the invention are illustrated according to its different angles of repose. Said system (A), differently from the system (Α') of prior art, is developed based on the fact that said center of gravity (3) of movable parts is immovable. It is observed that the most proper place, where the center of gravity (3) is kept immovable in every angle of repose of the system (A), is the focus (F) (at the same time, axis of the thermal receiver member (2)) of the reflector (1 ). Thus, center of gravity (3) of the movable parts of the system (A) is carried to the focus (F) of the reflector (1 ) by means of at least one counterweight (4). Position of the counterweight (4) is adjusted so as to stay at upper side (it is disclosed according to its angle of repose in Figure 3) of the member (2). In other words, the member (2) is present between the counterweight (4) and the reflective surface (1 ) At least one retaining profile (9) (these profiles (9) are a part of movable parts of the system (A) and thus, they are taken into consideration in weight balance) is used in order to keep the counterweight (3) in desired position.

The most proper position for the counterweight (4) is the position, where the reflector (1 ) is provided on the line (L) aligning focal point of reflectors (1 1 ) with the focus (F). Therefore, in the system (A) facing the sun, the counterweight (4) overshadows the thermal receiver member (2) and the focal point (1 1 ). Especially, since there is no part belonging to reflective surface (1 ) (it is structural feature of the system (A)) on the focal point (1 1 ) (in other words along the line aligning focal points (1 1 ), this shadow has no negative effect on efficiency of the system (A). In addition, counterweight's (4) thin form extending along the surface (1 ) has a role in above mentioned situation. The counterweight (4) is produced from desired material (for example concrete) so as to meet said necessities. Especially when material with high density is used, the counterweight (4) will be small in volume and thus, this allows the shadow to narrow.

By ensuring that the counterweight (4) used in the solar trough system (A) of the invention illustrated in figures 3-4 and the center of gravity (3) of the movable parts of the system (A) are kept immovable, energy needed for operation of the system (A) is saved (in comparison with system (Α') of prior art). Moreover, this situation causes that both movable parts and immovable parts grounding these parts to the floor become lighter. Reducing the weight of movable parts helps decrease the energy needed for operation of the system (A).

Claims

1. A solar trough system (A) comprising at least one trough-shaped reflective surface (1 ) directing sunlight to its focus (F) and rotating about its focus (F), which is its own rotation axis; at least one thermal receiver member (2) provided on focus (F) of the surface (1 ) and extending along the reflector (1 ) characterized in that centers of gravity (3) of movable parts of said system (A) are located on the focus (F) of reflector (1 ) in every angle of repose of the reflector (1 ).

2. A solar trough system (A) according to Claim 1 , characterized in that it comprises at least one counterweight (4) which keeps the center of gravity (3) of movable parts of the system (A) on focus (F) of the reflector (1 ).

3. A solar trough system (A) according to Claim 2, characterized in that the focus (F) is in between the counterweight (4) and the reflective surface (1 ).

4. A solar trough system (A) according to Claim 3, characterized in that the counterweight (4) is located on the line (L) aligning the focal point (1 1 ) of the reflector (1 ) with the focus (F).

5. A solar trough system (A) according to Claim 2, characterized in that it comprises at least one retaining profile (9), which retains the counterweight (4).