WO2009028000A2

WO2009028000A2 - Improved robot collector for large lens solar concentrators

Info

Publication number: WO2009028000A2
Application number: PCT/IN2008/000551
Authority: WO
Inventors: Thirumalai Anandampillai Aparna; Thirumalai Anandampillai Vijayan; Thirumalai Anandampillai Anandvishnu
Original assignee: Aparna Thirumalai Anandampilla; Vijayan Thirumalai Anandampill; Anandvishnu Thirumalai Anandam
Priority date: 2007-08-30
Filing date: 2008-09-01
Publication date: 2009-03-05
Also published as: WO2009028000A3

Abstract

A large composite lens(1) formed of smaller lens segments(2) assembled on supports (11) having pillars(12) refracts concentrated solar rays onto heating coil(3) fitted atop radial arm(4)moving on track (27). High temperature boiling oil in heating coil(3 ) gets heated, flows to insulated hot tank(5) via insulated tubes and then the secondary exchanger(6) for steam, air heating, air-cooling, desalination etc in the same device. Cooled oil goes to cool oil tank (7) for recirculation to heating coil (3). Pumps (19,20) maintain the oil circulation Electronic controls (17)with sun and thermal sensors (18), monitors the system temperature, working, both pumps and cleaning. A top arm (13) with a dust blowing air holes(15) and a motorized rollable cover(14) protects the lens (1) in dust and nights. The radial arm's motor 26 rolls it's wheel 29 on the circular track (27) around central pivot 8 capturing continuous concentrated solar energy efficiently with negligible sun tracking losses. Many lenses form a solar farm.

Description

A IMPROVED ROBOT COLLECTOR FOR LARGE LENS SOLAR

CONCENTRATORS

Technical Field This invention in general relates to energy needs. More particularly this invention relates to novel, cheap and efficient large lens solar concentrators for thermal and various uses with simpler sun tracking.

State of Art Existing solar thermal energy devices are: 1.flat plate collectors using a metal heating plate inside a glass sheet box with no concentration and giving 60-70*C hot water only. 2. Mirrors [plane and dish type] focusing on to a point with good concentration, but needing a large structure that needs sun-tracking [wasting energy] 3. Small lenses that concentrate a small energy and also needs sun tracking. There are no simple devices to harness large solar energy. Sun wi'l shine for million years more and is the driver of this earth's life- wind, hydro electric, ocean energies -all are solar based! Solar energy is variable and is around 1000-watts/sq. meter area/ hour useful for few hours, more in summer, more on clear days, more near equator!

Ideal solar thermal device should be: 1. Concentrating for high temperatures for efficient energy transfer and minimal losses.2 Cheap for all nations. 3. Long life with minimal solar tracking energy losses. 4. Easy to fix, run and use. 5. Safe and reliable. 6. Multiple uses from the same device 7. Storage for night supply. There are no simple devices as of now!

The following description gives critical examination of the solar devices known in the art. It also discusses the shortcomings of the conventional methods. Further in order to overcome the problem associated with solar harnessing, the invention offers the solution to overcome the impediments in the construction and the process of using the same.

Constraints in all existing lens or mirror solar thermal devices are as follows: 1. There is no economic, efficient concentration of energy. 2. The devices are too big, complex and inefficient.

3. Sun tracking losses from morning to evening is large as the whole device is moved.

4. The maintenance needs are large as these are open to nature.

5. Single use only. Accordingly the object of the invention is to identify the solutions for problem associated with the conventional solar thermal energy conversion. An extensive search has been carried out using the Internet and related patent specifications were studied for single large lens concentrators with minimal sun tracking losses. Since the present invention is radically different, in using a single large lens with a small focus area and a moving heating coil for various uses in the same device, the inventor is unable to site any patent specification out of the available databases. Multiple small lenses placed on an arc or hemisphere do not concentrate as each small lens creates a separate focus and not unified focus! Multiple small lenses do not concentrate for the total area of lenses but only separate weak focuses! Lenses do not focus at a single point but forms a travelling focus on opposite side of sun- west in morning and east in evening- opposite of mirrors. Tilt of earth also makes this travel a moving arc. This traveling focus, a basic truth is not revealed in all lens concentrator patents and solved till date. Our earlier application WO2005/050103 is also for a large lens concentrator, but has a mirror below the lens that reflects to a tower coil. This is not efficient as mirrors are to be designed for that geographic area - not good for mass use. Eliminating the mirror and tower coil needed further research too. This invention is simpler, lower cost, mass adaptable to all areas of earth too.

The invention is directed to a novel type of solar concentrator using simple large lenses with least sun tracking losses. Lenses are better than mirrors: 1. Lenses concentrate to the ground, ground based heat use is cheaper than mirrors that direct and concentrate up on to a tower [more cost] or upper focus 2.Lenses do not need to be tracked, only zero weight solar rays need to be tracked eliminating a huge energy loss. 3. Lenses are easy to maintain as mirrors corrode. 4. Plastic lenses are lower than mirrors in weight and easy to make.

Accordingly it is the primary object of the invention to invent a novel single large solar concentrator, which is unique in design and construction, working and use.

It is another object of the invention to indicate a novel process by virtue of which the device can be effectively utilized. Further objects of the invention will be clear from the ensuing description.

Summary of the invention:

The device comprises of a very large diameter composite convex glass or plastic lens say 2-4meters or more diameter supported on pillars. The lens concentrates and focuses hot solar rays to ground- west in morning, east in evening. A black, rough, copper coil supported on a moving frame and placed below the lens heats a high boiling liquid, from cool oil tank and the nested fluid is sent to a hot oil tank and a secondary heat exchanger that creates, steam, desalination, ammonia based refrigeration, etc, The cooled oil is pumped back to the cool oil tank for reuse. A series of closely packed lenses forms a larger solar farm. A Tollable cover enclosed in a top arm, covers the lens on dusty nights. This arm has also a lens cleaning dust blower and remover to keep the lens clean for maximal efficiency. Temperature sensing of hot coii, hot oil tank, secondary exchanger feed an electronic control for efficient use. The heating coil of smaller weight is placed on a radial frame moving on a circular track for tracking the focused rays all day instead of the whole heavier device as in dishes.

Statement of Drawings:

These and other objects and features of the invention will become more apparent upon perusal of following description taken in conjunction with accompanying drawings wherein: Figure 1 shows in elevation the details of single large lens concentrator. Figure 2 shows the various components lens, radial frame, supports and oil circuit. Figure 3 shows the exploded view of the action, in hot day.

Figure 4.shows a solar farm with one lens covered. Figure 5. shows some uses in secondary exchanger.

DESCRIPTION OF PREFERRED EMBODIMENTS

The following specification describes salient features of invention, the method of construction, the method of use and the advantages of the novel invention.

The novel device has a single novel very large lens- plano-convex or bi convex that receives a large area of solar rays and focuses to a smaller area for high temperature heating, e.g. 4 meter lens has an area of 12 sq.meter with 12 KW/hour heat energy available, more than needed for a family. The lens focuses down making collection easier and cheaper than mirrors that focus up and needing tov/ers to collect energy. A smaller black, rough thick copper tube heating coil collects the focused rays and heats the circulating high boiling liquid that is heated to more than 150* C and sent to the hot oil tank. This hot oil is fed to a secondary heat exchanger coil, where water is made into steam for running a generator, or process chemical reactions, desalination, etc. and cooled oil is sent to the cool oil tank and repumped to heating coil for continuous thermal power.

The novel device according to the invention is fixed to any open surfaces or roof for easy solar collection.

The novel concentrator according to invention is better because the thermal conversion is better with higher concentration, has lesser radiation losses, multiple uses in the same device, such as steam for cooking, power, air cooling or heating. Solar tracking is simpler with lower energy losses, as the zero weight concentrated rays are focused to the heating coil by a novel smaller radial mover. Multiple uses in same device with lower sun tracking energy loss are new. Special feature of the invention is that it is easy to set up, run, and stop even by illiterates too.

The novel device has higher efficiency due to higher temperature heating, small sun tracking energy losses, multiple uses. The existing mirror and lens solar concentrators have not been improved for decades. The object of the invention is to overcome the inherent defects. To this end the new invention is addressed!

The device comprises of a very large diameter [say four meters or more, with a two meter focal length] transparent composite glass or plastic lens 1, formed of series of segments2 arranged in a circle forming a big composite lens, with single focusing. A moving black, rough surface copper tube coil 3 with the high temperature boiling oil feeds to a hot oil tank 5, from where the hot oil is circulated by a pump 19 to a secondary heat exchanger coil 6 for various uses as steam, etc. The cooled oil is sent to a cool oil tank 7 with a pump20 to feed the heating coil tubes 3for more heating. The oil flow is shown as arrows in pipelines in fig 4 The cool oil tank has a filter to clean oil. The secondary heat exchanger coil can produce steam, desalination, process steam, etc as needed. The heating coil is fixed and travels on a frame 4. The frame has a central pivotδ rotating around a central tube 9 and an outer radial frame 4 thai has on its top the heating coiB. The radial arm has a bottom motor 26 to run the wheel 29 to roll on a circular track 27. The circular track 27 & radial frame 4 position the heating coil precisely for high heating and follows the travelling focus. The radial frame wheel 29 and circular track 27 has position indicators that is easy to plot and control. The cool and hot oil tubes are connected to heating coil and electric cable 30 for motor26 is fixed to the radial arm 3. The electronic control 17 senses position of solar focus and move the motors26 of the radial arm to exactly follow travelling sun for continuous energy. Sun sensor in the simplest form is another small lens of identical miniaturization with tiny focus falling on a light detecting panel. This gives the coordinates of the focus to move the frame motor26 on circular track 27 to collect all energy continuously. The control also controls the oil circuit, feeding the secondary exchanger through pump 19 of the hot oil tank 5(day and night), cool oil through pump 20 of the cool tank to feed the heating coil 3. Fig 3 shows the working of single lens. The sunrays in the morning (M) strike the lens and refract to west and vice versa in the evening (E), heating the moving coil all day for continuous energy harvest with low sun tracking losses. As the sun moves, the radial frame motor runs the wheel 29 on circular track 27 and follows the refracted focus for steady heating. The moving coil 3 is connected to cool oil tank 7 for cool oil feed and the other end to hot coil tank. The moving coil and the large lens are a new novel combination for low sun tracking losses with a concentrated energy never before possible. At night lens is covered and frame 4 comes to morning position.

The lens segments 2 (fig 2) when arranged side by side forms a large composite lens, each segment having three or more holes 10, with spring loaded bolts that hold the lens segments on a supports 1 1, forming a large lens supporting mesh. The support 11 has the holes for bolts to fix the lens segments. After assembly, the lens looks as in fig 1 top - a large convex lens. The lens support has lower three or more pillars 12 to fix to the ground! A cleaning and covering arm 13 with a rolled plastic/ cloth cover 14, and a dust blowing holes 15 is supported on one pillar for covering the lens in dusty nights and cleaning the lens for maximal transparency of the lens. A motor 16 in the arm rolls the cover. The motor 16 [electrical or compressed air] can rotate to spread or roll the cover in opposite direction. The air holes are supplied from a compressed air source. The arm 13 sweeps just above the lens for cleaning or covering.

The heat exchanger 6 has the secondary coil fixed around the hot oil tube from the hot oil reservoir. The secondary coil has water circulating for steam production to run steam turbines or use the steam for processing of chemicals, desalination, etc. Cooled oil is sent to the cool oil tank7 for recirculation.

Electronic control 17 has at least four circuits- oil, lens cleaning & covering, sun tracking and communication. The oil circuit has the temperature sensor 18 (direct thermocouples or infrared remote sensors) on heating coil3, hot oil tank5, secondary exchangerό and calculating the oil feed to heat exchanger for smooth power by operating the hot oil tank pump 19, feeding cool oil to the heating coil from the cool oil tank through pump 20 and sending this data to communication circuit too. Lens cleaning is by blowing air through holes 15 in top arm. Covering lens on dusty rainy days or sun set or heating coil over heating can be modified with soft ware for rolling the motor 16 to cover or reroll the lens cover 14 in the top arm 13 by remote control. Sun sensor circuit rolls the frame motor 26 and the wheel 29 on the track 27 to always get the hot focused lens rays onto the radial frame heating coil 3. Solar farm will have more complex control. The control has communication circuit to relay all working data to a wired or wireless display A series of lens concentrators as in fig4, serves as a compact solar farm. The lensesl, are arranged closely to save on land space. All the heating coils send hot oil to a central hot oil tank 5, which feeds the secondary coil 6 for various uses. The cooled oil is sent to the cool oil storage tank 7 that feeds the radial frame coils, forming a large farm. The cleaning armsB may all act at the same time to clean the lens, cover or expose to sun. The cover 14 is covering one lens in fig 4.A electronic control controls all the lenses working.

The lenses are made as segments of a circular lens to minimize the cost of fabrication, transport and erection or service. The segment can be made for area needed [power needed], refractive index of the plastic or glass used, by molding in desired dies with needed cavity and surface for bending and concentrating light. Instead of a giant single lens, a series of segments are easy to make and assemble. The appropriate pillars and lens support with appropriate holes 10 for bolts is fabricated. The lens segments are fixed by spring-loaded boltslO for correct single focusing on lens supports! The copper coil is fixed on the radial frame 4. The oil circuit- cool oil tank, tubes, heating coil, hot oil tank, secondary exchanger is connected as needed and temperature sensors 18 fixed. The secondary circuit (not detailed in figures) is completed say, water reservoir, secondary exchanger, and turbines, cooled steam condenser, water pumps and needed pipes. Once lenses are exposed to sun, the rays of sun are focused to heating coil, heating the inside oil, which flows to hot oil tank5 and fed to the secondary exchangerό where steam is formed and oil cools, cool oil is sent to cool tank 7 for recirculation. The sun rays in morning is refracted to west, midday down, evening to east, then striking the heating coil fig.3, for continuous power. The hot oil tube, hot tank and hot oil tube till secondary exchanger is insulated to reduce radiation loss.

The lens can be cleaned by a blast of compressed air from holes 15 in the arml3. The coverl4 is spread by switching on the motorlό, to cover on dusty nights or rerolled for sun exposure, fig.4 where a lens is covered. A series of lenses will form a solar farm fig 4. After cleaning of lens, all the lenses focus to the lower heating coil, heating the oil and sending to hot oil reservoir5, secondary exchanger όwhere power is made, cool oil collected to cool oil tank 7for reuse. All lenses create more energy, without equipment shadow effect as seen in existing devices like mirrors. Electronic controls for single or solar farm is easy. Temperature sensors 18, attached to heating coils3, hot oil tank5, secondary coilβ, feeds the electronic control 17 which then pumps hot oil to secondary coils for continuous power! The control in the evening can cover or in morning clean and uncover the lenses! Insulated hot oil tanks supply energy in nights. The device can be modified. The lens can be made as two or more circular segments with different segments for each circle for a single focus. In the entire figures one circular segment are shown. Adhesive may fix lens segments on lens supports instead of bolts. Pillars number and structure may be varied. A heating coil can be fixed on a free robot (not shown, and moved for sun orientation) directly for heating oil. With the same lens device instead of circular track the moving heating coil can be assembled on a cross beam traveling on parallel linear tracks for various focus position in all seasons. The circuit for heating can produce steam directly in the heating coil. Heating ceil in frame 4 can be enclosed in a glass cage to minimize radiation losses. Heating coil may be circular or wavy in contour. Secondary coil can feed all the various needs as, steam for power22 with a turbine generator28, process heat, air-dry ing23 with a fan , air-cooling by heating the ammonia generator24 in ammonia cooling, desalination 25as in fig.5 with a water evaporator that then cools vapour (shown as dots) for clean water and unevaporated solute. The coil can also be mounted on free wheels but hot oil tubes will get twisted breaking the device. Compressed air can be used to move pillar arm 13 to roll or cover the lens and clean the lens too.

Instead of sun position indicator and needed circuit, the motor may be timed for slow rotation on the circular track. The radial frame is run from morning to evening and returns to morning position the same day to avoid twisting of heating coil connections to cool and hot oil tubes. The cool oil tubes may be plastic but hot oil tubes are of metals only.

It will be apparent to those skilled in the art that modifications to the invention described herein can readily be made without departing from the spirit of the invention. Protection is sought for all the subject matter described herein including any such modifications.

Advantages of the new invention:

1. Energy conversion by lens takes place at ground level saving on tower costs.

2. Low weight lens and supporting pillars are cheaper to erect.

3. Moving hot coil has low sun tracking energy losses! 4. Energy concentration is more, as large lens area focuses to smaller area.

5. Life of device is more, as there are few moving parts.

6. Using high boiling oil in insulated tubes and tanks reduces thermal losses.

7. Lens focus tracking is new with easy cleaning of lens at ground level.

8. Electronic control with (remote) sensors easily monitors and runs the device. 9. The same device has now many uses by changing the secondary circuit.

10. Every open space serves as energy creator without pollution.

1 1. Solar is eternal and device will give us pollution free energy in day or night

Claims

We Claim: l.A large lens solar concentrator with an improved collector comprising of a large composite convex lens 1 fixed on a supporting lens framel l assembled on pillarsl2, the said lens having below it a heating coil 3 fitted atop a radial disposed frame 4, the said radial frame has on its underside a small electrical motor 26 connected to and rotating a wheel29, the said wheel 29 rolling on a circular track 27, the said heating coiB connected to the cool oil tank 7at one end and to a hot oil tank 5 at the other end, the said hot oil tank is connected to a secondary heat exchangerό, the said concentrator having an electronic control 17 to circulate oil for continuous power and moving the said radial frame 4 on the said circular track 27 for all sun positions, the said pillar has an upper arm 13 with a Tollable coverl4 for lens covering and air holes!5 blowing compressed air for lens cleaning,

2.A solar concentrator as claimed in claim 1, wherein the radial frame 4 has at the top rough, black fast heat absorbing copper or aluminium coiB and below an electrical motor 26, the said motor rotating a wheel 29 rolling on a circular track 27, the said top heating coil 3 is connected to cool and hot oil tanks, the said radial frame having at the inner end a pivot hole 8 fitting over a central pipe9, the said frame 4 moves with the said top heating coil on the said wheel 29 on the said circular track 27, the said frame motor 26 is connected and controlled by the electronic controller 17 through the motor electric cable 30, such that the hot focused changing sun rays always fall on the said heating coil 3.

3.A solar concentrator as claimed in claim 1, wherein the composite plano-convex or convex lens comprises of transparent glass or plastic lens segments2 arranged in one or more concentric circles as needed, each said lens segment2 having three or more holeslO, the said lens segments are assembled on matching lens support frame 11 by spring loaded bolts in the said holes 10, such that all the lens segments when assembled form a single focus lens, concentrating a large area of solar collection on to a small area of focus of high heat source.

4. .A solar concentrator as claimed in claiml, wherein two or more pillarsl2 has at the top the circular lens framel 1 divided into segments sized as that of the said lens segments2, each said lens support segment having matching holes 10 with a spring loaded bolt to receive and hold the lens segments2 and to form a stable support for the single focus composite lens, one of the said pillars has an upper arm 13, this said arm having inside a motor to roll or , unroll the lens coverH and also inside a tube with air holes 15 connected to a compressed air source to blow away lens dust for a clean, clear lens, this said arm is placed above the said lens and swung by the electronic control 17 for cleaning and covering the lens.

5. A solar concentrator as claimed in claim 1, wherein cool oil tank 7 with stored high temperature boiling liquid has a discharge pump 20 connected to heating coiBof the said radial frame 4, the hot end of the heating coil connected through insulated tubes to insulated hot oil tank 5 ( provided with pump 19) and then a secondary exchanger 6, wherein heat is transferred and cooled oil is fed to the cool oil tank7 for continuous power.

6. A solar concentrator as claimed in claim 1, wherein the said secondary exchanger 6 has the hot oil tube with hot oil from the said hot oil tank5 and another heat removing coil for steam creation, air heating, ammonia generator or desalination, etc circuits, the said exchanger tubes are made from good heat conducting metals.

7. A solar concentrator as claimed in claim 1, wherein temperature sensors 18 (direct or infrared remote) of the radial frame heating coil3, hot oil tank5, secondary exchangerό are connected to an electronic controll9 that controls and regulates oil flow from the cooloil tank to heating coil3, the hot oil tank and the secondary exchanger for correct and continuous oil circulation for continuous energy.

8. A solar concentrator as claimed in claim 1, wherein a series of large lenses are arranged on pillars side by side, to form a solar farm, all the radial frame 4 heating coils of all lenses are connected to a larger central hot oil tank 5 with a secondary exchangerό and a larger cool oil tank7, all hot oil of all lenses forming large heat source for a massive power plant.

9. A solar concentrator as claimed in claiml, wherein the said electronic controll7 has the control circuits for oil circulation, lens cleaning, sun tracking and communication, the said oil circuit has the temperature sensorslS of the heating coil, hot oil tank and secondary heat exchanger to run the oil tank pumps for continuous power, the said sun tracking circuit comprising of a sun sensor and the radial frame motor26, lens cleaning and covering circuit controlling top arm motor 16 ,the lens cover 14 , dust air holes 15, the said communication circuit relaying the total working to a display device.

Dated this Twenty ninth day of August, 2008