IL108110A - Roof structure including concentrating solar collector units - Google Patents

Description

9 3 4 3 "ROOF STRUCTURE INCLUDING CONCENTRATING SOLAR COLLECTOR UNITS" "ΐ Ίϊηο na»n >οίηρ irmm Wian xx ru-in" THE APPLICANTS: :D>gp-inn TECHNION RESEARCH & DEVELOPMENT n"ya rrniain n nn^ H'iDOfi torn FOUNDATION LTD. TECHNION CITY, ,1Ί>-ΐ3οη-η»Ί HAIFA 32000. .32000 na¾n THE INEVNTOR: 1. PROF. GERSHON GROSSMAN imnut iiBiA 'ana 18, HAHORSHA ST., 18 ntmnn aim HAIFA 34525 34525 iifl»n ROOF STRUCTURE INCLUDING CONCENTRATING SOLAR COLLECTOR UNITS.

The invention relates to utilization of solar energy at intermediate temperatures, particularly for industrial purposes, by incorporating a plurality of solar heat collectors in the roof structure of industrial and other buildings. It relates particularly to serrated roof structures constructed of premanufactured modules, with each module provided with at least one collector unit.

BACKGROUND OF THE INVENTION.

The most important object of utilizing solar energy instead of using combustible fuel for industrial and other purposes, is to protect the world from overheating by increasing the carbon dioxyde contents of the atmosphere and creating the so-called greenhouse effect. There is the other argument that fossil fuel will eventually be exhausted, and that other energy sources will have to be dicovered and used, whereof atomic energy is much favored but for the difficulty to dispose of the waste products. The main drawback of collecting solar energy are the high cost of conventional solar installation, as well as the requirement of large spaces which are not usually available in towns, but are available on the wide roofs of industrial buildings.

Therefore one of the most promising applications of solar energy is in the area of process heat generation for industry. While the greater part of the effort in solar research has traditionally been spent on developing devices for domestic use, it has long been recognized that industrial use has a far greater potential. Apart from the quantities of energy involved, industrial use of solar energy is particularly suitable for the following reasons : Industry works mostly during day time when solar energy is amply available, whi 1 e domest ic use is either at night for heating purposes or in the morning for bathing or showering, requiring costly storage of the heat collected during day time.

Industry consumes energy on a steady basis all year round, thus making effective use of the capital invested in solar collecting equipment, in contradistinction to domestic use which is mainly seasonal. industrial installations are generally located in one-story buildings, thus offering a large roof area for collection of solar radiation. a_nd Industrial systems are large compared with domestic ones and_ enjoy the advantages of large scale economy, as well as ready availabilty of personnel for maintenance of the equipment .

Since the industrial consumer requires mostly steam at temperatures between 150 to 300° C. it would be useless to cover a roof area with the common domestic type of flat collectors which can effectively heat water up to a temperature of 80° C. On the other hand, most of the conventional high-temperature solar heaters are not suitable for industrial use both with regard to the initial high investment and high maintenance costs.

The solar collectors suitable for heating a liquid to higher temperatures include reflectors which concentrate solar radiation on tubular or spherical absorbers and must track the sun. The most commonly used solar heater for high temperatures, especially for generation of electric energy, comprises a mirror or reflector of parabolic, cross section and a tubular absorber positioned in the focus of reflected radiation. This kind of collector is angularly movable by sensor and mechanical means, effecting the axis of the parabola to always point in the direction of the sun during its travel across the sky. These solar heaters are highly effective for generation of the high temperatures for which they are needed, but are not cost-effective for most industrial enterprises which require intermediate outlet temperatures of up to 200° C, and are definitely not suitable for incorporation in the roof of an industrial building, which is the object of the present invention.

The inventor of the present solar heating assembly for industrial purposes has made preliminary tests with solar collectors which included a stationary reflector of hemispherical shape inclined in Southern direction and 4a cylindrical absorber having its axis directed towards the moving sun by sensor and mechanical means. These tests showed that a thermal efficiency of up to 47.6% could be achieved at temperatures of up to 150° C, and are proof that this type of collector can be readily incorporated in a roof constructed of premanuf actured modules.

Using solar energy will ultimately profit industry by saving the expense of other sources of energy, be it fuel or electric power, especially if the initial investment is not costly.

It has been experienced that reflectors dim after a certain period and thereby cause considerable decrease of efficiency, and it is one of the objects of the present invention to permit renewal of the reflecting surface at low cost, whenever necessary. - 3A - P R I O R A R T 108,110/2 US 4.424.804 describes a reflector which holds a centrally positioned, rotating solar radiation collector. The patent does not refer to a roof composed of a multitude of reflectors.

US 4.257.400 describes a roof adapted to collect solar radiation. It is characterized by a surrounding wall which reflects solar radiation onto the roof surface which collects the radiation.

US 4.461.277 relates to a radiation collector assembly which is adapted to be mounted on the walls or the roof of a building. It permits change of direction according to the direction of solar radiation.

US 5.217.600 discloses a building having its outside walls and its roof covered by hollow, partly transparent blocks . Water flowing through these blocks is heated by solar radiation and is gathered for heat storage.

JA 31-133834 describes a solar heater including a trough-shaped reflector and a tubular collector extending above the reflector.

J A 52-1545 describes a sloping roof covered by trough-shaped solar heaters.

IL 47932 shows a trough-shaped solar reflector.

IL 62476 likewise describes a solar heater in the shape of trough-shaped radiation reflectors.

SUMMARY OF THE INVENTION.

The industrial roof stucture with incorporated solar energy collectors is composed of a plurality of modules arranged in rows and columns to form the serrated roof of an industrial building. Each module comprises a sloping roof portion having a low edge and a high edge and having its surface inclined towards the South - in the Northern hemisphere - , and an upstanding portion supporting the roof portion along its high edge. The roof portion comprises at least one solar reflector in the shape of a spherical segment forming a downwardly extending concave recess which is lined with a light-reflecting material. A cylindrical absorber is fastened in a universal joint positioned above the reflector at a point coinciding with the center of the sphere of the reflector and is movable by sensor and servo-motor means to direct its axis in the direction of the sun during its passage across the sky.

The inclination of the roof depends on the latitude of the location of the industrial building and will increase with increased distance of the location from the equator. The upstanding portion is preferably vertical and provided with windows in a conventional manner. It may constitute an integral unit together with the roof portion or may be separately manufactured and assembled on site. The low edge of the roof portion is preferably separated from the upstanding portion of the adjoining row of modules by a gutter or walkway, thereby ensuring that solar radiation will reach the reflector even at low position of the sun. The separate modules are either mounted side by side on beams or girders supported by columns or, in case they are of sufficient length and carry several reflectors, are supported by spaced columns.

The modules may be constructed from different materials such as concrete, asbestos cement, metal sheeting, fiber-reinforced plastics or any other material which is suitable for roof covering, especially if it can protect the insde of the building from being heated by solar radiation. An important advantage of the invention is the fact that heat will not penetrate into the building through the areas covered by the reflectors, independent of the material of which the modules, are made.

BRIEF DESCRIPTION OF THE DRAWINGS.

Figure 1 a, b, c, illustrates an inclined collector showing the focus of reflected radiation at three positions of the sun, Figure 2 is an isometric view of a roof module containing a solar collector of the invention, Figure 3 is a vertical section of the solar collectpr illustrated in Figure 2, Figure 4 is an isometric view of an elongated roof module containing four collectors in a row, and Figure 5 is an isometric view of an industrial building covered by a roof composed cf modules each containing a solar col lector.

DETAILED DESCRIPTION OF THE DRAWINGS.

Figure 1 shows a solar collector having a reflector in the form of a spherical segment inclined towards the sun at an angle dependent on the geographical latidude cf its location and an absorber in the form of a cylinder having its upper end pivotably mounted in a point coinciding with the center of the sphere. Figure 1 shows the collector at three different positions of the sun, 1a at noon, lb in the forenoon or afternoon, and 1c morning or evening, wherein the sun rays reflected by the spherical surface are focused on the absorber with its axis coinciding with the direction of the solar radiation. The figures show that even in the morning when the rays impinge on the reflector at an oblique angle, up to 60% of the reflector surface is active in concentrating the radiation on the cylindrical absorber.

The module illustrated in Figures 1 and 2 is supported by two channels 3. one in front and one in the rear and includes an inclined roof portion 1, a substantially vertical supporting portion 2. The channels are open towards the top and serve as gutters, and as spacers serving to remove the inclined roof portion from the adjoining support portion to allow solar radiation to reach the collector even at low positions of the sun. Another purpose of the channels is to provide ready access to the personnel with tools for cleaning and maintaining the solar collectors. The roof portion is substant i a f ly square and contains a reflector in the form of a concave spherical segment 4 lined with reflecting sheet sectors 5. A narrrow channel 6 at the bottom of the reflector serves for draining rain water. In order to provide a strong roof construction the channels 3 are positioned on roof girders extending between columns or the channels are themselves constructed in the form of girders. As shown in Figure 2, the channels constitute separate components supporting the low edge of the roof portion 1 and the vertical portion 2 on one flange each, wherreby the roof portion constitutes a separate portion and supports the roof portion along a dividing line 15. The vertical portion is shown to be interrupted by openings 16 representing windows. On the other hand. Figure 2 illustrates a module where the roof portion, the vertical portion and one channel form one integral unit which has to be supported on girders spanning the distance between columns of the building.

A cylindrical absorber 10 containing a heat-absorbing liquid, such as e.g. water, is pivotally supported in the center of the sphere by a universal joint 11 held at the top of a tripod 12, the latter being firmly anchored in the inclined roof portion. Sensor elements and servomotors or other actuators, which are schematically indicated by numeral 13 serve tc detect the direction of solar radiation at all times and to shift the absorber axis in parallel with the radiation direction. Piping serving to circulate the liquid through the absorber and to convey it from and to a consumer inside or outside the building is preferably incorporated in the tubular legs of the tripod or may be in the form of separate hoses or tubes .

Figure 4 illustrates a roof module of four times the length of the module of Figures 2 and 3, containing four collectors in a row. It comprises a long roof portion which contains four concave reflectors of the type shown in Figures 2 nd 3, a vertical portion 102 of equal length and a front channel 103. The rear end of the unit rests on the adjoining channel 103 supporting it along the vertical portion. The vertical portion is advantageously interrupted by window openings 106. This kind of module has the advantage of obviating the necessity of erecting supporting girders, since the construction of the module is strong enough to support itself between columns 105. Solar absorbers and their angular moving mechanisms are provided over each reflector in a manner known from Figures 2 and 3.

It is obvious that the suppcrting portion 2 or 1 C2 shown to be vertical in the aforegoing embodiments, may be inclined in outward or inward direction, but it can be shown that a substantially vertical wall has certain advantages in regard to preventing sun or rain from intruding into the building.

The building shown in Figure 5 has its entire roof composed of solar collecting modules, which may be of any of the three types described in the foregoing. As mentioned before, the inclination of the roof portion depends on the latitude of the location of the building and will decline towards the equator.

It is reiterated that the modules may be premanufactured of concrete, reinforced plastics, fiberglass, galvanized sheeting or any other suitable material, in accordance with climatic or other conditions.

The absorber may be of any kind known to the art. it consists preferably of a helically wound pipe having its respective ends connected to piping and being enclosed 4 in a cylindrical envelope of a transparent material. The space inside the envelope may be evacuated or filled with air or any other gas. The support may be in the form of a tripod as shown in the drawings, but may be of any other shape, as long as it permits a maximum of sun radiation to reach the collector surface by minimizizng shading.

The direction adjusting mechanism may be of any kind known to the art and generally includes two sensor elements and two servo-motors arranged at right angles so as to direct the universal joint with the absorber in the direction of the sun rays.

The concave collector is lined with a, light-reflecting material which should reflect solar radiation over a large portion of the spectrum. A preferred material is highly transparent plastic sheeting lined with a coat of silver or aluminum, which can be readily applied to the curved surface of the reflector and to be replaced after having d immed .

Claims (21)

108,110/2 - 9 - C L A I M S

1. A roof structure composed of a plurality of building modules arranged in rows and columns and being configured to convert solar energy into process heat, wherein each said module contains at least one solar collector, each said module including, a rectangular roof portion having a low edge and a high edge and having its surface inclined towards the Scuth (in the Northern hemisphere), said roof portion containing -at least one solar reflector in the shape of a spherical segment forming a downwardly extending concave recess with its upwardly extending surface lined with a light- reflecting material , an upstanding portion supporting said roof portion along its high edge, an oblong solar heat absorber containing a circulated liquid and being pivotally attached to a universal joint positioned above said , .·. spherical segment substantially at the center of the sphere forming said segment, sensor means and actuator means for coordinating the axis of said oblong absorber to coincide with the changing direction of the solar radiation reaching said solar col lector , conveying means for circulating said liquid through said absorber and conveying heated liquid to consumers and returning cooled liquid to said absorber.

2. The roof structure of Claim 1, wherein each said module contains one solar collector.

3. The roof structure of Claim 1, wherein each said module certains several solar collectors in a row. - 10 -

4. The roof structure of Claim 1, wherein a channel forming a gutter or a walkway extends along said low edge of said module.

5. The roof structure of Claim 1, wherein said roof portion and said upstanding portion are in the form of an integral unit.

6. The roof structure of Claim 1, wherein said roof portion and said upstanding portion are in the form of two separate components, wherein said high edge of said module is supported on said upstanding portion.

7. The roof structure of Claim 1. wherein said upstanding portion is in vertical position.

8. The roof structure of Claim 1, wherein said upstanding portion is in inclined position.

9. The roof structure of Claim 1, wherein said upstanding portion is provided with window openings.

10. The roof structure of Claim 4, wherein said channel is in the form of a web and two upstanding flanges.

11. The roof structure of Claim 10 wherein said low edge of said roof portion and said upstanding portion are supported by one flange each of said channel.

12. The roof structure of Claim 4, wherein said channel is integrally connected to said roof portion along its low edge.

13. The roof structure of Claim 4, wherein said roof portion, said upstanding portion and said channel form an integral unit.

14. The roof structure of Claim 1, wherein said universal joint carrying said absorber is supported by a tripod having its three legs firmly connected to said roof portion.

15. The roof structure of Claim 1, wherein said liquid circulating means are in the form of piping extending inside said legs of said tripod.

16. The roof structure of Claim 4, wherein each said module contains four solar collectors in the form of four concave spherical segments in an oblong rcof portion, and wherein said upstanding portion and said channel of corresponding length form an integral unit with sai roof portion .

17. The roof structure of Claim 1, wherein each said module is made of concrete.

18. The roof structure of Claim 1, wherein each said module is made of a plastic material.

19. The roof structure of Claim 1, wherein each said module is made of galvanized metal sheeting.

20. The roof structure of Claim 1, wherein said light reflecting lining is in the form of transparent plastic sheeting lined with a layer of metal, such as silver or aluminum.

21. The roof structure as claimed In any of Claims 1 through 20 and substantially as described with reference to the accompanying drawings. FOR THE APPLICANTS,