Title of Invention

"A GLASS-LAMINATED NON-VACUUMED SOLAR HEAT COLLECTION ELEMENT"

Abstract

A. glass laminated non-vacuumed solar heat collection element comprising an super cermet coated inner metallic tube (11), which is co-axially covered with an outer pyrex glass tube (12) characterized in that, two layered polymer ring with inner layer of Kevlar and outer layer of Teflon (13), the ring being provided at both the ends of the combined assembly of the said inner metallic tube and said outer glass tube, wherein the said polymer ring is adapted to close either end of the both the said tubes and is also adapted to hold the inner metallic tube in position; the half portion of outer surface of upper semi-cylindrical portion of the said glass tube is coated with a silver reflecting surface (14), followed with a further two layered coating of copper and the outer surface of thus coated glass tube is laminated with another semi-cylindrical glass tube (16) by using polyvinyl butyral film (15) in between the said two tubes by heating in a vacuum chamber at 140-145° C.

Full Text

FIELD OF INVENTION This invention relates to a glass-laminated non-vacuumed solar heat collection element. The device collects the solar heat reflected from the reflectors of a solar device and the heat thus collected is used for applications such as process heat and solar thermal power generation. PRIOR ART Conventional Heat Collection Element (HCE) are vacuumed heat collection element absorbers. These consist of a selectively black cermet coated metal tube (1) co-axially covered with an outer Pyrex glass tube (2) by means of metallic bellows (3) on both ends. The length of outer glass tube and inner co-axial metallic tube is around 4m and the outer diameter of outer glass tube is around 120mm and that of inner metallic tube is 70 mm. There is a high vacuum to the extend of 10-4 torr in between metallic tube and the pyrex glass tube which works as a transparent insulation to reduce convective heat losses. The outer glass tube is hermetically sealed/ fuzed at points (4) with steel bellows (3) at either end. The steel bellows are welded with inner metallic tubes at points (5) at both the end, at an elevated temperature. Heat Collection Element (HCE) is installed along the focal line of the parabolic trough reflector, where the sunrays are concentrated to produce high temperature heat. This heat is transferred by the heat transfer fluid to heat exchanger to generate steam, thus converting solar energy to thermal energy which can be used for process heat or for generation of thermal power. A drawback of the above heat collection element (HCE) is that outer glass tube of HCE breaks on account of thermal stresses, abnormal vibrations due to high wind and earthquakes, accidental hitting during cleaning, etc. The breakage of glass tube adversely affects the vacuum between the outer glass tube and inner metallic tube, which in turn affects the performance of HCE. The replacement of broken outer glass tube increases the maintenance cost. Another drawback of the above type of HCE is that vacuum between the outer glass tube and the inner metallic tube gets gradually reduced on account of migration of hydrogen ions from disintegration of heat transfer fluids, through metallic tube into the vacuum area. The reduction in vacuum causes heat losses resulting in decrease in efficiency of the device after few years of its use. The disintegration of heat transfer fluids takes place due to high intensity cosmic rays or due to the high stagnant temperature. Still another drawbacks of the above type of HCE is that there is 3% heat loss due to bellows on either end of the HCE. Further drawback of the above type of HCE is that metal to glass sealing is a complex technology which is expensive. According to US Patent No. 4300538. the solar energy receiver comprises of a cylindrical glass shell (6) formed around a heat conductive tube (7) for heat exchange fluid. Vacuum is created between the glass shell and the heat conductive glass tube. A pair of heat collection elements is positioned within the glass tube (Fig 2) to collect and concentrate solar energy on the inner tube. A disadvantage of the above heat conductive glass tube like conventional HCE, is that vacuum between outer and inner tube gets gradually reduced over a period of time, due to various factors given above. Another drawback is that the outer glass shell is vulnerable to breakage due to thermal stresses/ vibrations etc. Still another drawback of the above arrangement is that the positioning of a pair of elements makes the fabrication of HCE as complex. According to Patent No. DE 19 840, 181 a parabolic trough collector has a reflector in the form of a parabolic trough. The heat collection element is in the form of an absorber tube (9), which runs along the focal line of the reflector. A secondary reflector (10) in the form of a flat plate is arranged on one side of the absorber tube. A drawback of the above heat collection element is that positioning of a secondary reflector involves a complex technology. Another drawback of the above heat collection element is that it also suffers form the drawbacks associated with conventional heat collection elements. OBJECTS OF PRESENT INVENTION An object of the present invention is to provide a heat collection element (HCE), which minimizes the chances of breakage of outer glass tube of the HCE. Another object of present invention is to provide a heat collection element between the inner metallic tube and outer glass tube, which obviates the need for a vacuum between the inner metallic tube and outer glass tube. Still another object of present invention is to provide a heat collection element (HCE), which obviates the need for expensive technology of hermetic sealing of outer glass tube with inner metallic tube by means of steel bellows, thereby considerably reducing the cost of HCE and also simplifying the process of manufacturing of HCE. Further object of present invention is to provide a heat collection element, which is considerably lower in cost by about 40%. Still further object of present invention is to provide HCE wherein radiative and convective heat looses from the upper half of the glass tube are minimized to improve the performance of HCE. STATEMENT OF INVENTION According to this invention there is provided a glass laminated non-vacuumed solar heat collection element comprising an super cermet coated inner metallic tube, which is co-axially covered with an outer pyrex glass tube characterized in that:- a) two layered polymer ring with inner layer of Kevlar and outer layer of Teflon, the ring being provided at both the ends of the combined assembly of the said inner metallic tube and said outer glass tube, wherein the said polymer ring is adapted to close either end of the both the said tubes and is also adapted to hold the inner metallic tube in position; b) the half portion of outer surface of upper semi-cylindrical portion of the said glass tube is coated with a silver reflecting surface, followed with a further two layered coating of copper and the outer surface of thus coated glass tube is laminated with another semi- cylindrical glass tube by using polyvinyl butyral film in between the said two tubes by heating in a vacuum chamber at 140-145° C. DESCRIPTION OF FIGURES The invention is illustrated with accompanying drawings, which illustrate an embodiment of the present invention. The principles and features of the present invention can be incorporated in variant embodiments, which are intended to be within the scope of the present invention. The drawings are not intended to be taken restrictively to imply any limitation on the scope of the present invention. In the accompanying drawings:- Fig 1:- shows the conventional heat collection element. Fig 2:- shows the heat collection element disclosed in US patent No. 4, 300, 538. Fig 3:- shows heat collection element disclosed in patent No. DE 19, 840,181. Fig 4:- shows the heat collection element of the present invention. Fig 5 (a):- shows the three dimensional view of heat collection element. Fig 5 (b):- shows the side view of heat collection element. DESCRIPTION OF INVENTION W.R.T.DRAWINGS Referring to Fig 4, the heat collection element (HCE) of present invention comprises of a super cermet coated metal tube (11) co-axially covered with Pyrex glass tube (12). A high temperature polymer ring (13) is provided at either end of said outer glass tube to close both the ends of the glass tube. The said polymer ring (13) is also adapted to hold the inner metallic tube (11) in position. The upper half portion of the said outer glass tube is coated with silver reflective surface (14). The length of the HCE is about 4 meters and outer glass tube has thickness of 3.5 mm, outer dia of 120 mm while the inner metallic tube has outer dia of 70 mm. Referring to Fig 5 (a) and 5 (b), the said silver reflective surface is coated with two protective layers of copper (not shown). Such a coated surface is laminated with a semi-cylindrical glass tube (16) using polyvinyl butyral (PVB) film (15) and heating in a vacuum chamber at 140-145° C. The performance of the proposed HCE is nearly same as that of vacuum HCE known in the art It is to be understood that the process of present invention is susceptible to modifications, changes and adaptations by those skilled in the art. Such modifications, changes and adaptations are intended to be within the scope of the present invention, which is further set forth under the following claims: WE CLAIM; 1. A glass laminated non-vacuumed solar heat collection element comprising an super cermet coated inner metallic tube (11), which is co-axially covered with an outer pyrex glass tube (12) characterized in that:- a) two layered polymer ring with inner layer of Kevlar and outer layer of Teflon (13), the ring being provided at both the ends of the combined assembly of the said inner metallic tube and said outer glass tube, wherein the said polymer ring is adapted to close either end of the both the said tubes and is also adapted to hold the inner metallic tube in position; b) the half portion of outer surface of upper semi-cylindrical portion of the said glass tube is coated with a silver reflecting surface (14), followed with a further two layered coating of copper and the outer surface of thus coated glass tube is laminated with another semi- cylindrical glass tube (16) by using polyvinyl butyral film (15) in between the said two tubes by heating in a vacuum chamber at 140-145° C. 2. A glass laminated non-vacuumed solar heat collection element as herein substantially described and illustrated with accompanying drawings.

Documents:

1159-del-2004-abstract.pdf

1159-del-2004-claims cancelled.pdf

1159-del-2004-claims.pdf

1159-del-2004-complete specification (granted).pdf

1159-del-2004-correspondence-others.pdf

1159-del-2004-correspondence-po.pdf

1159-del-2004-description (complete).pdf

1159-del-2004-drawings.pdf

1159-del-2004-form-1.pdf

1159-del-2004-form-19.pdf

1159-del-2004-form-2.pdf

1159-del-2004-form-3.pdf

1159-del-2004-gpa.pdf

abstract.jpg

abstract1.jpg