OA13095A

OA13095A - Device for heating a container by solar power.

Info

Publication number: OA13095A
Application number: OA1200500205A
Authority: OA
Inventors: Lauge B Gevitz
Original assignee: Osprey Systems Aps
Priority date: 2003-01-22
Filing date: 2004-01-22
Publication date: 2006-11-10
Also published as: WO2004065861A1; ZA200505772B; AP2005003358A0; BRPI0406869A

Abstract

The present invention relates to a device (1) for heating a container (12) and its content by solar power, which device (1) comprises at least one reflecting element (2), at least two end walls (3, 4) having means for fastening (10) said reflecting element (2) in between said at least two end walls, whereby said reflecting element (2) is forced to be formed in a shape which concentrates solar rays into a focusing area at a fixed point or fixed band irrespective of the sun's (13) position in the sky during the day, a transparent cover (5) arranged for providing an enclosure between said end walls (3, 4) and said reflecting element (2), and a placement unit (8) arranged to fix said container (12) into said focusing area, wherein said device (1) is collapsible, where said reflecting element (2) is flexible and foldable, where said end walls (3, 4) are removable and where said placement unit (8) is flexible and foldable. The present invention furthermore relates to a method for positioning a solar collector device (1) comprising a reflecting element (2) with opposite surfaces having a shared longitudinal axis, wherein said solar collector device (1) is placed on a surface with said longitudinal axis positioned preferably in an east/west direction.

Description

Qsprey Systems APS

Device for Heating a Container by Solar Power

Scope of the invention

The présent invention relates to a device for heating a container and its content bysolar power, which device comprises at least one reflecting element, at least two endwalls having means for fastening said reflecting element in between said at least twoend walls, whereby said reflecting element is forced to be formed in a shape whichconcentrâtes solar rays into a focusing area at a fixed point or fixed band irrespectiveof the sun’s position in the sky during the day, a transparent cover arranged forproviding an enclosure between said end walls and said reflecting element, and aplacement unit arranged to fix said container into said focusing area.

Background of the invention EP 1106188 describes a container for the disinfection of drinking water. Thecontainer comprises a body having a fîrst and a second side and defining an interiorfor receiving a fluid, the first side being defined by a UV-transparent layer, and thesecond side being defined, at least in part, by a second layer that either reflectssunlight or generates heat in response to solar energy.

In this type of container disinfection primarily occurs by using the UV light of thesolar radiation. This is possible over a long time, but because most of the solarradiation takes place in the inffared part of the solar spectrum, this part of the lightpasses through the drinking water with a very small heating effect. Heat absorptionoccurs after the inffared part of the spectrum has passed through the water and hitsthe back surface of the container. This leads to a quite low disinfection capacity inthis type of container. DK 2000 00 737 L describes a pasteurising device for disinfection of water. Thedevice comprises two containers connected by a thermostatic shut-off valve andwhere a first container is placed in a solar collector. The thermostatic shut-off valve 1 1 3095 allows water from running from the first container to the second container when thewater in the first container has reached a certain température.

Due to the thermostatic shut-off valve the heated water runs into the second containeras soon as the water reaches a certain température. This results in only partialdisinfection of water because bacteria and viruses typically are only efficiently killedby maintaining a certain température over a certain period of time. Furthermore, thethermostatic shut-off valve is a bottleneck in the disinfection process becauseimpurities/large particles in water from lakes, rivers, streams, or polluted wells couldclog the thermostatic shut-off valve, thereby reducing the efficiency of thepasteurising device. DK 2001 00090 U3 describes a pasteurising device for disinfection of water. Thedevice comprises boxlike cabinet in which a container and a reflecting element areplaced. The solar rays are reflected by the reflecting element into the container,thereby heating the content of the container.

The pasteurising device is built and assembled as a boxlike cabinet in the form of astationary construction. The stationary construction of the cabinet reduces theusefulness of the pasteurising device because it takes up much space during transportand storage. Furthermore the pasteurising device is shown as having optional extraequipment, e.g. a vertical rod for rotatable mounting of the device above the ground,and with further extensible reflecting éléments which complicate the use of thepasteurising device.

Object of the invention

It is the object of the présent invention to provide a simple, inexpensive, reusable andefficient device primarily for disinfection of water by using solar power.

This can be achieved with a device according to the preamble of claim 1 and whereinsaid device is collapsible, where said reflecting element is flexible and foldable, 2 13095· where said end walls are removable and where said placement unit is flexible andfoldable.

Description of the invention

In this way it is possible to achieve simple and inexpensive disinfection of thecontent in a container if the device is placed in the sun with longitudinal axis of thereflecting element preferably in an east/west direction.

The efficiency of the device dépends on the energy content of the solar radiation. Inareas with suffîcient solar energy available, the device may provide efficientdisinfection of the content of a container in less than an hour, and may thus be usedsuccessfully in régions where water is contaminated by microorganisms.

The device according to the invention can disinfect water for at least 4-6 persons perday. In many tropical areas there is suffîcient water, but the water is often infected atthe source, and the actual distribution of the water often contributes to furthermicrobiological contamination. By using the device according to the présentinvention a container can be filled with water which may or may not hâve beenfiltered.

The container is then closed so as to seal off the water from the environment duringthe disinfection process. The container may remain closed and used for storing thedisinfected water without fear of recontamination. Thus no contamination can takeplace during the disinfection process or subséquent storage.

To obtain disinfection of the content of the container, the container is placed on aplacement unit inside the enclosure provided between said end walls, said reflectingelement, and said transparent cover. 3 13095·

The solar rays are reflected by the reflecting element and concentrate into a focusingarea at a fixed point or fixed band, irrespective of the sun’s position in the sky duringthe day.

The placement unit is positioned inside the device in such manner that the containeris placed at the focusing area, and the concentrated solar rays will heat the content ofthe container, whereby a température is reached that is sufficient for disinfecting thecontent of the container.

The fact that the end walls are enclosed around the reflecting element by saidfastening means forces said reflecting element to be formed in a shape whichconcentrâtes solar rays into a focusing area at a fixed point or fixed band irrespectiveof the sun’s position in the sky during the day.

To provide a simple, inexpensive and reusable device said device is collapsible,where said reflecting element is flexible and foldable, where said end walls areremovable and where said placement unit is flexible and foldable.

Hereby a device can be formed that takes up very little space during storage andtransport, just as the weight of the device is very low. Devices can be packed readyfor use, and a high number of devices can be transported in a container to placeswhere a sudden demand arises, for example after a disaster. A big problem after a disaster in an area is supply of drinking water because waterpipes and wells are damaged, and thus there is a high risk that people are infected bycontaminated water.

With the device according to the présent invention it is possible to disinfectcontaminated water in a very efficient way, even in areas with broken infrastructure,as soon as big numbers of the device can be transported into the areas by e.g.helicopters. 4 13095·

Furthermore can a device be disassembled into several parts and then either betransported to another area for immédiate use, or be cleaned and stored away for lateruse.

In order to make it possible to place the device on e.g. the ground or suspended on anupright surface, said device furthermore comprises a collapsible and foldable supportunit that either: - has a recess with a form complementary to the outer form of the reflectingelement, whereby the device will fit into the support unit, or - is in the form of a number of fittings that can be attached to the reflectingelement.

As the support unit is collapsible and foldable, it is easy to pack it together with thereflecting element and the end walls. Thus ail devices are provided with a supportunit.

Altematively, the device is formed with a pointed or coned part or a protrudingelement which can be driven into the ground or into a surface, thereby keeping thedevice in a firm position during the disinfection of the content of a container.

To ensure that the solar rays are concentrated in a spécifie focusing area saidfastening means of said end walls comprise recesses for receiving said reflectingelement, which recesses form said reflecting element in a Winston parabolic cuspform.

The geometry of a Winston parabolic cusp form is provided by taking twosymmetrical half paraboloidal cylinders, which meet the following conditions: - the focus of one cusp must be placed on the opposite cusp, and 5 1 3095 - the cusp must be tilted inward until its top is parallel to the Winston axis, andthus parallel to the other cusp.

Altematively said fastening means of said end walls comprise recesses for receivingsaid reflecting element, which recesses form said reflecting element into a Trombe-Meinel form.

When the reflecting element is assembled, its form of can be other types than theWinston parabolic cusp or Trombe-Meinel form. The important thing is that the formof the reflecting element ensures that the solar rays are concentrated in a spécifiefocusing area at a fixed point or fixed band irrespective of the sun’s position in thesky during the day.

In this way, the correct and stable shape of the solar collector is achieved bymounting the reflecting element between the end walls. If a force presses the endwalls against each other, the reflecting element is kept in the correct position in asimple manner. The fastening means hâve sufficient force to secure the reflectingelement and may comprise bars suspended between and affixed to both end walls.

In one embodiment of the présent invention said fastening means of said end wallscomprise protrusions for support of the reflecting element, which protrusions areplaced on both sides of said reflecting element.

The protrusions can be used for fixing a thin reflecting sheet that will gain strengthand stability when forming the curvature defined by the end walls and theirprotrusions. Thus a very thin flexible foil may be achieved in the correct form whensuspended between at least two end walls that are kept apart by at least two spanners.Spanners may be foldable so as to allow for a device to be fully collapsed duringstorage and transportation.

In order to make it possible to assemble the device into a firm construction, saiddevice furthermore comprises securing means for fastening said end walls to said 6 13095· reflecting element. These securing irieans can be fastening clips which are mountedalong the reflecting element and grab around the edge of each end wall, therebykeeping the end walls around the reflecting éléments.

To ensure that the container is placed in the focusing area of the concentrated solarrays, the container is placed in a placement unit which constitutes an elastic andexpandable sleeve, a pipe and/or a flexible and foldable mat.

The placement unit furthermore protects the reflecting element, end walls and/orcover from melting/being damaged if the content of the container reaches hightempératures.

In a preferred embodiment of the invention the placement unit is a mat made of aninsulating material which is placed at the bottom of the enclosure provided by thereflecting element and the end walls.

When it is necessary to use the device for disinfecting e.g. water, a container isplaced onto the mat and in the focusing area of the reflecting element.

In another embodiment of the invention, the placement unit is a sleeve, which can beelastic and be expanded by containers where the sleeve is in heat-conducting contactwith at least one container. Hereby flexible securing of at least one container isachieved. Containers of different sizes should be placed in almost the same positionso that the focusing b and is inside the container for a range of container sizes.

The sleeve can be made of a heat-conducting material. In this way the part of thesolar energy collected by the sleeve will be conducted to the surface of the container.

The sleeve can be connected to a bar that is connected to both end walls and placedover the focusing band of the reflecting element. This sleeve contains at least onecontainer, which container is placed in the focusing band of the reflecting element. 7 13095·

In this way, a container is placed so that most of the solar energy reflected by thereflecting element is concentrated inside the container. Just using a sleeve is aninexpensive method for keeping the container in place.

In a third embodiment of the invention the placement unit is a tube, which forms aprotective, flexible and transparent shield formed as a tube, attached to andsuspended between two end walls. This tube may form an inner space, sealing off thesolar collector from the outside environment. Foldable spanners may keep the shieldsfully suspended and in shape.

The tube is placed around the focusing band of the reflected solar radiation, andaccess to the tube is through at least one endplate. The use of a tube allows anefficient change of containers.

The tube can penetrate the end walls, and containers can be placed inside the tubewithout further access to the device. The tube may hâve covers at the openings inorder to isolate it.

In one embodiment of the présent invention said placement may unit furthermorecomprise a foldable bar which is connected to both said end walls and placed oversaid focusing area of said reflecting element. During the use of the device, thisfoldable bar stretches the reflecting element by pressing the endplates away fromeach other.

Said placement unit can be made of a heat-conducting material, whereby heat fromthe enclosure of the device can be transported into the content of the container. Thisis especially important if the placement unit is a sleeve or a tube sealing off thecontainer from direct contact with the air in the device.

The transparent cover arranged for providing an enclosure between said end wall andsaid reflecting element ensures that solar energy and heat do not dissipate from thedevice to the environment during use, thereby enhancing the heating efficiency of the 8 13095· content in the container. The cover mnst be transparent in order to allow solar rays toenter the device.

The containers may be bottles that can be opened and closed, e.g. with a screw cap,which bottles are placed in the sleeve or the tube. Common soft drink bottles such asPET bottles are available at a very low price in almost ail parts of the world, and theycan be used as personal water containers. Each time a bottle is fîlled, it must beheated in the device for disinfection prior to use. A cooling period is necessarybefore drinking, because the water in the containers is heated to at least 65°C. PETbottles can be used several times, but they will not last forever. However, as thesebottles are inexpensive and available in large numbers, it is possible to easily obtainnew bottles.

Altematively, a flexible, foldable bag, made of heat conductive material may beinserted as a water container in areas where bottles are not available.

For use in non-tropical areas, the device can hâve at least one of said end walls madeof a transparent material, and an inner side of at least one of said end walls isprovided with a reflecting material.

Hereby the device becomes more efficient in non-tropical areas. Part of the light canpenetrate one of the end walls and be reflected so as to heat the container. Light mayalso be reflected from the opposite end wall and further reflected to heat thecontainer.

Altematively at least one of said end walls is made as a one-way mirror allowingsolar rays to enter the device, while reflecting and capturing solar rays inside thedevice.

The reflecting éléments can be formed of a flexible surface having:a reflecting foil, - a reflecting paper, 9 13095 · - a layer of reflecting paint, and/ora reflecting textile.

Instead of removing the transparent cover each time a container is placed into the5 device, one of the end walls can be provided with an opening through which it is possible to place a container on the placement unit.

To reduce the heat loss from the device through the opening, it is provided with aflap, arranged for allowing access to the opening during changing containers, or for 10 barring the opening during the disinfection process.

The first step to reduce the risk of infection from contaminated water is to disinfectthe water by e.g. using a device according to the présent invention. The heating ofwater will kill a certain amount of bacteria or viruses, but it is necessary to keep the 15 water at a high température over a period of time to further reduce the risk ofinfection.

Therefore every container could be provided with a thermometer with a memoryunit, so that it is possible to check whether the water at some point during the 20 disinfection process has reached the wanted température or not, while at the sametime, the container is maintained in the device for a certain period of time.

The device could be used on a large scale or for industrial purposes by forming adevice with a substantial length, and instead of using exchangeable containers, a pipe 25 is placed on the placement unit. Hereby it is possible to disinfect large amounts ofwater, in batches or continuously.

For obtaining the optimum incident solar radiation of a solar collector devicecomprising a reflecting element with opposite surfaces having a shared longitudinal 30 axis, said solar collector device is placed on a surface where said longitudinal axis ispositioned preferably in an east/west direction. 10

According to the theoretical principles behind the use of solar collectors, theefficiency of the solar collector device during a whole day approximates its optimumwhen the shared longitudinal axis of the opposite surfaces of a reflecting element ispositioned preferably in an east/west direction.

If the solar collector device is placed in an east/west direction, the incident solarradiation in the moming and aftemoon will be allowed to pass through the end wallpointing towards the sun, whereby the total amount of solar rays available for thedisinfection process is high.

If the solar collector device placed in a north/south direction, the incident solarradiation in the moming and aftemoon will be partly blocked by the longitudinalsurface of one of the reflecting éléments, whereby the total amount of solar raysavailable for the disinfection process is reduced.

At noon there will be no or only minimum différence between the incident solarradiation into the solar collector device, regardless of the position.

In order to obtain the maximum solar input at winter and/or solstice, the deviceaccording to the invention has an acceptance angle of 30 degrees and/or may in oneembodiment of the présent invention be formed so that it is possible to tilt the devicearound the shared longitudinal axis of the reflecting element of the device.

Short description of the drawing

The invention is described in more detail below with reference to the accompanyingdrawing in which:

Fig. 1 shows a device according to the invention,

Fig. 2 shows an exploded view of the device, 11

Fig. 3 shows an end view of the device,

Fig. 4 shows a device with a container according to the invention,,

Fig. 5 shows a plane view of the device in Fig. 4,

Fig. 6 shows a device positioned in two different positions proportionally to thecorners of the world, and

Fig. 7 shows an alternative embodiment of the invention.

Detailed description of the invention

Fig. 1 shows a device 1 according to the invention, comprising a reflecting element2, end walls 3, 4, a transparent cover 5, and a support unit 6.

The reflecting element 2 is placed between end walls 3, 4, and the device 1 isprovided with an internai enclosure by attaching the transparent cover 5 to the endparts of the reflecting element 2 and the upper parts of end walls 3,4.

The reflecting element 2 is forced by the end walls 3, 4 into a pointed form which iscomplementary to a recess 14 in the support unit 6, thereby allowing the device 1 tobe placed in a stable manner.

To make it possible to position or change a container (not shown) in the device 1,without removing the cover 5, end wall 3 is provided with an opening (not shown).The opening (not shown) is covered by a flap 7, arranged for allowing access to theopening (not shown) during exchange of containers (not shown) or for barring theopening (not shown) during the disinfection process. The flap 7 ensures that heat lossfrom the device 1 through the opening (not shown) is minimal. 12 13095-

The support unit 6 is shown as a plate with an opening folded into a triangularsupport unit. When the plate is folded, the opening will form the recess 14 whereinthe lower part of the reflecting element 2 is placed.

The end walls 3, 4 hâve a slightly pointed upper edge to force the cover 5 into a roofridge form, thereby allowing any condensed water on the underside of the cover torun out against the reflecting element and down into the device.

Fig. 2 shows an exploded view of the device 1 and the varioüs éléments of which itconsists. The device 1 comprises: - a reflecting element 2, - an end wall 3 with an opening 11 at the bottom part, - an end wall 4; both end walls 3, 4 are provided with recesses 10 arranged forreceiving an edge part of the reflecting element 2, thereby forming the reflectingelement 2 into a Winston parabolic cusp form, a transparent cover 5, arranged for attachment to the end parts of the reflectingelement 2 and upper parts of end walls 3,4, - a support unit 6 with a recess 14, where recess 14 has the same form as thebottom part of the reflecting element 2, an insulation mat 8 is arranged for being placing at the bottom of the reflectingelement 2 so that it can protect the reflecting element 2 against excess heat ffomthe heated content of the container (not shown), and - a’number of securing means in the form of fastening clips 9 having a hook partarranged for gripping around the edge part of each end wall 3, 4, thereby keepingthe reflecting éléments in place between the end walls 3, 4. 13 1 30S5

Fig. 3 shows the device 1 in a end view, where flap 7 covers the opening (not shown)provided at the bottom part of the end wall 3. The end wall 3 is shown as having aWinston parabolic cusp form and with a with an upper edge part having in a roofridge forai.

Fig. 4-5 show the device 1 with a container 12 in the form of a bottle placed inside. Itis possible to remove or place a container 12 in the device through the opening 11.The container is placed on a mat (not shown) and in the focusing area of theconcentrated solar rays.

Fig. 6 shows how the position of the device 1 affects the obtainable incident solarradiation.

When the solar collecter device 1 is placed in an east/west direction and the sun 13travels from east to west, the incident solar radiation in the moming and aftemoonwill be allowed to pass through the end wall pointing towards the sun, whereby it ispossible to utilize the optimum amount of incident solar radiation.

Oppositely, when the solar collecter device 1 is placed in a north/south direction, andthe sun 13 travels from east to west, the incident solar radiation in the moming andaftemoon will be partly blocked by the longitudinal surfaces of one of the reflectingéléments. Thus the utilization of the incident solar radiation is lower.

Fig. 7 shows an alternative embodiment of the invention where device 20 comprisesend walls 22, 23. Between these end walls 22, 23 a reflecting element 21 is placedwhich is formed as a cusp mirror.

Between the end walls 22, 23 and over the reflecting element 21, a bar 26 is placed,which bar 26 opérâtes as an energy absorber support carrying a sleeve 25. The sleeve25 is placed in the focusing area of the reflecting element 21, and the sleeve 25comprises a container 24 for absorption of solar energy. 14 13095.

The device 20 is covered by a transparent top 29 which top 29 is positioned on themechanical support 27 for the cusp mirror. The device 20 also comprises amechanical support 28.

Device 20 may be disassembled for transport and storage whereby its height isreduced to only a few centimètres. The reflecting element 21 may be a single foldedsheet that is only a few millimétrés.

If the reflecting element 21 is foldable because it is formed of a flexible film, and themechanical supports 27 and 28 are also foldable, only the bar 26 must be removed, orthe bar 26 could also be a foldable bar.

In this case, it will be possible to remove the top 29 and fold ail the mechanicalsupport éléments 27,28, and then, by also folding the sleeve 25 and the mirror 21, tocompress the whole device 20 to a thickness of only a few centimètres.

The transparent top 29 can be formed in a way in which the end walls 22, 23 and theéléments folded between these end walls 22, 23 can be placed in a dépréssion thatcan be formed in the transparent top 29.

In this way, the top 29 becomes part of a container, thereby providing efficientstorage and transport of the device 20.

One of end walls 22, 23 can be formed to fit into the dépréssion in the transparent top29 so that this end wall becomes the other part of the container which contains theentire device 20.

In this way efficient transport and storage at a low cost can be achieved.

The reflecting element 21 can be formed in the Trombe-Meinel curve for achieving aconcentration band in the same area, independently of the sun’s position in the sky. 15

Claims

13095· CLAIMS

1. Device (1) for heating a container (12) and its content by solar power, whichdevice (1) comprises at least one reflecting element (2), at least two endwalls (3, 4) having means for fastening (10) said reflecting element (2) inbetween said at least two end walls, whereby said reflecting element (2) isforced to be formed in a shape which concentrâtes solar rays into a focusingarea at a fixed point or fixed band irrespective of the sun’s (13) position inthe sky during the day, a transparent cover (5) arranged for providing anenclosure between said end walls (3, 4) and said reflecting element (2), anda placement unit (8) arranged to fix said container (12) into said focusingarea, characterised device (1) is collapsible, where said reflecting element(2) is flexible and foldable, where said end walls (3, 4) are removable, andwhere said placement unit (8) is flexible and foldable.

2. Device (1) according to claim 1, characterised in that said device (1)furthermore comprises a collapsible and foldable support unit (6).

3. Device (1) according to claim 1, characterised in that said fastening means(10) of said end walls (3, 4) comprise recesses for receiving said reflectingelement (2), which recesses form said reflecting element (2) in a Winstonparabolic cusp form.

4. Device (1) according to claim 1, characterised in that said fastening means(10) of said end walls (3, 4) comprise recesses for receiving said reflectingelement (2), which recesses form said reflecting element (2) into a Trombe-Meinel form.

5. Device (1) according to any of the daims 1-4, characterised in that saidfastening means (10) of said end walls (3, 4) comprise protrusions forsupport of the reflecting element (2), which protrusions are placed on bothsides of said reflecting element (2). 16 13095

6. Device (1) according to claim 1, characterised in that said placement unit (8)constitutes an elastic and expandable sleeve, a pipe and/or a flexible andfoldable mat. 5

7. Device (20) according to claim 6, characterised in that said placement unit(25) furthermore comprises a foldable bar (26), which is connected to bothsaid end walls (22, 23), and which is placed over said focusing area of saidreflecting element (21). 10

8. Device (1) according to any of the claims 6-7, characterised in that saidplacement unit (8) is made of a heat-conducting material.

9. Device (1) according to any of the claims 1-8, characterised in that at least 15 one of said end walls (3, 4) is made of a transparent material, and an inner side of at least one of said end walls (3, 4) is provided with a reflectingmaterial.

10. Device (1) according to any of the claims 1-9, characterised in that said 20 device (1) furthermore comprises securing means (9) for fastening said end walls (3,4) to said reflecting element (2). 17