FR2482708A1 - Solar energy traps made of intersecting multichannel tubes - to eliminate use of superficial glazing - Google Patents

Abstract

A solar energy trap comprises a grid array of twin integral concentric pipes so that the prim. heat transfer fluid circulates through the core passages and a sec. fluid circulates through the outer passages. Used for external use without ancillary enclosures, being less susceptible to differential thermal stresses and loss of containment of the sec. fluid than mono-bore pipe systems within larger casings holding the sec. fluid. For a given system bore, provides a relatively large interface between the prim. and sec. fluid flow systems - the flow rate in the latter may be throttled to provide an insulating jacket for the core passages and smooth response to external temperature variations. Also less susceptible to erosion in desert climates than designs receiving heat via glazing. Opt. the multi channel profiles are made of ethylene-propylene diene moulding or extrusion matls., pref. filled with carbon black to enhance heat capture and transfer at the core passage walls . The grid is assembled from intersecting tube profiles by adhesive or vulcanisation bonding.

Description

 The present invention relates to a solar collector installation intended, in particular, for the supply of hot water for sanitary, heating or air conditioning uses.

There are multiple solar installations using a heat transfer fluid either to heat a liquid for sanitary use, or to be used for space heating
The problem of solar collector installations is relatively complex and the solutions to such problems depend essentially on the sites of use.

Indeed, a solar collector installation must take into account a large number of parameters such as latitude, sunshine, extreme temperatures, temperature variations over the years, temperature variations between day and night, etc. .

Most currently known solar installations include solar collectors mainly using the greenhouse effect. Very schematically, such sensors are constituted by relatively flat boxes, with preferably insulating walls, except for the front face which is constituted by a transparent surface of glass or synthetic material. Inside the box, a circuit is provided for the heat transfer fluid which heats up under the effect of solar radiation to which the panel is exposed.

 The main drawback of such installations is their current cost which is relatively high. This results from the fact that, on the one hand, such installations are not yet manufactured in sufficiently large series and, on the other hand, the materials used and the type of construction.

Beside sensors, such installations, notably with greenhouse effect, in which the temperature of the heat transfer fluid can very widely exceed 1000 and reach temperatures close to 1400, it is necessary to provide circuits for the heat transfer fluid, means of security to avoid excessive pressure, as well as weather conditions, means of heating to prevent the heat transfer fluid which is in the general case of water9 from freezing after sunset.

 The costs of setting up such solar collector installations are not negligible because of the specialized manpower necessary to carry out the installation, the connection works on existing sanitary or heating water circuits, etc.

 Examination of the various solutions known in the field of solar collector installations has shown that, contrary to all appearance, these installations are not particularly usable in hot or even desert countries, where precisely such installations should have the best performance.

Indeed, among the difficulties encountered there are paradoxically those which arise from the climatic environment.

 In desert countries, sand winds are relatively frequent. However, these winds have a very corrosive action and experience has shown that such sand winds which have an effect analogous to industrial sanding, very quickly deteriorate the transparency of the panes of conventional solar collectors, and considerably reduce their efficiency.

 It is also not possible to use any synthetic materials to replace glass because the effect of ultraviolet rays causes very rapid aging of the synthetic materials and reduces the lifetime of the assembly.

In some countries, maintenance or repair problems can also be encountered, which should not be overlooked. However, the absolute priority which must be satisfied by a solar collector installation, intended to be mounted in the most diverse places, is its extreme reliability or above all a reduced, even negligible maintenance, allowing if necessary makeshift repairs.

 Finally, the installation must be able to be transported easily, without risk of deterioration and allow on-site assembly by labor not specialized in this particular field.

 The present invention proposes to create an installation with solar collector intended, in particular, to be mounted in the most different places, which is of an extremely easy assembly, requires practically no maintenance allows makeshift repairs, either light and above all not very fragile during transport.

To this end, the invention relates to an installation with a solar collector, characterized in that the collector consists of a tube comprising an inner wall and an outer wall, delimiting an inner enclosure and an outer enclosure, each of these enclosures forming a path of circulation of a heat transfer fluid, the interior enclosure forms the path for the main heat transfer fluid and the exterior enclosure the path for the auxiliary heat transfer fluid, these two interior and exterior walls of the tube being connected together to form a mechanically integral assembly , respecting the spacing between the two parts.

 When the auxiliary heat transfer fluid of the external enclosure does not circulate, a buffer increases the efficiency of the sensor and makes it less sensitive to rapid variations in solar radiation, for example during the passage of clouds. In all cases, since the apparent surface area of the tube is equal to the diameter of the external wall multiplied by the length of the tube, this surface is clearly larger than if the tube were constituted only by the internal wall alone.

 The temperature that the heat transfer fluid circulating in such a tube makes it possible to achieve is much higher than that of a single tube because, in addition to the amplification of the surface exposed to the radiation, there is also a magnifying glass effect and or of radiation concentration on the interior wall, in the case of a transparent exterior envelope.

The invention also relates to a method of manufacturing a sensor installation. This process is characterized in that double-walled tubes are made, to the diameter of the tubes of the sensor itself and of the collectors, coaxial holes are made in the inner wall and the outer wall of the tubes intended to constitute the collectors, section of external wall along a generatrix passing through holes, the tubes are put in place, first fixing the end having internal walls in the holes then, after positioning and fixing, this external wall is fixed in
the corresponding tro @ and the cut is closed.

Thanks to this process, all of the sensor mounting is done in the factory, at the installation destination location it will suffice to set up the sensor and make the few simple connections.

The present invention will be described in more detail with the aid of various embodiments shown diagrammatically in the appended drawings, in which -
- Figure 1 is an axial sectional view of a sensor tube according to the invention;
- Figure 2 is a schematic plan view of a sensor made using tubes according to Figure 1
- Figure 3A is a detail sectional view along III-III, of Figure 2 and Figure 3B is a perspective view.

- Figure 4 is a sectional view along IV-IV of Figure 2
- Figure 5 is a diagram of a support device according to the invention
- Figure 6 is a schematic sectional view of the installation of a sensor on a terraced roof of a building.

 The installation according to the invention, with solar collector is intended to allow indifferently the supply of domestic hot water, the supply of hot water for heating, or the supply of heat, or alternatively used as a refrigerant circuit, supplying an air conditioning system.

 In fact, depending on the periods of the year or the day, it may be advantageous to use this installation with a solar collector, either as an installation actually constituting a solar energy collector, conveyed by a heat transfer fluid which supplies a heat storage device or domestic hot water, or a reverse-function heat exchanger, which for example at night radiates and exchanges heat with the interior to cool the heat transfer fluid and provide refrigerants which are stored for use during during the day by an air conditioning system supplying cold.

 According to Figure I, the sensor is constituted by a tube with two walls 2, 3 connected by spacers 4. The inner wall 2 defines an interior volume 21 in which is the main heat transfer fluid. The outer wall 3 defines, with the inner wall 2 an auxiliary volume 31 in which there is an auxiliary heat transfer fluid.

 The fluids in volumes 21, 31 can be identical and circulate in the same way. It is also possible, depending on the use, to block the circulation of one of the fluids and to circulate only the other fluid.

Preferably according to the invention, when the sensor formed by tubes I according to 17 inventions functions as a solar collector, it is preferable, in order to have a lesser sensitivity of the installation to very rapid variations in solar radiation (passage of clouds, etc. ), circulating the heat transfer fluid in the interior volume 21 and leaving the auxiliary heat transfer fluid without circulation other than its convection movements, etc. in the intermediate volume 31.

 Depending on the sensor area required, the tube can be simply arranged in a coil or in any other way between an inlet for heat transfer fluid and an outlet for heat transfer fluid. However, in most cases, when a large catchment area is required, of the order of 50 to 100 m, such a solution cannot be envisaged because of the pressure drops in the tube between the inlet and the exit. In this case> an assembly with parallel connections of several tubes between an inlet manifold and an outlet manifold, constitutes the most interesting solution.

Such an arrangement is shown diagrammatically in FIG. 2 which shows a compound of an inlet manifold 10 and an outlet manifold 11. The inlet manifold 10 is connected to the outlet manifold 11 by segments of tubes 1 , parallel, located at a certain distance from each other.

The distance d is chosen according to a compromise, the two terms of which are as follows
- two adjacent tubes I, I must not cast a shadow on each other, when the sun is relatively inclined.

- the density of tubes I must be sufficient depending on the collection surface to be produced and the surface available for installation of the sensor.

Ideally, to prevent the tubes I, I from projecting shade onto each other, it would be desirable to move them very far away, in order to be able to make the most of solar radiation, even when the sun is very tilt to the horizon, for example at the beginning or at the end of the day. However, as at this time the radiation is weakly energetic since it crosses a larger layer of the atmosphere and this layer is often charged with humidity, such losses are not decisive and it is possible to accept during this period a certain shadow projection, in favor of a closer approximation of the tubes 1.

 FIGS. 3A, B and 4 show in section the construction of the inlet or outlet collectors 10, 11. These collectors preferably have the same shape and the same sections since there is no need to accelerate or to slow the circulation of the fluid in one of the collectors for the benefit of the other.

According to Figures SA, B, the manifold 10 consists of an outer wall 101 and an inner wall 102. The inner wall 102 defines a volume. inside 103 and the outside wall 101 defines with respect to the inside wall 102 an outside volume 104. The inside volume 103 is intended for the main heat transfer fluid and the outside volume 104 for the auxiliary heat transfer fluid. The two walls 101, 102 are connected by a spacer or a web 105 which hold them apart at the intended distance, whatever the deformations to which the tubes are subjected.

 At the place provided for the connection of each tube 1, the internal wall 102 has an orifice 106 and the external wall 101 an orifice 107. These two orifices are preferably coaxial.

 According to the invention, a simple method of manufacturing the manifold 10 (or 11) consists in producing a tube with two continuous walls 101, 102 and then in drilling the tube 10 with two walls laterally coaxially, and each time with two holes 106, 107, according to the planned distribution of the tubes 1 of the sensor.

To facilitate the installation and the assemblies it is advantageous to cut the external wall 101 according to a generator 108, between the holes 107, so as to be able to slightly disembowel the external wall 101 for the passage of the tools used for the welding of the front end. from the inner wall 2 of the tube 1, in the orifice 106.

Depending on the materials used for the manufacture of tubes 1 and 10 (materials which are preferably identical), it is possible to envisage different types of welding such as bonding, polymerization, vulcanization, etc.

Once the welding is carried out between the walls 102 and 2, the welding between the walls 101 and 3 can be carried out in the same manner at the level of the orifice 107 and of the cutoff according to the generator ioa.

It is particularly interesting that the tubes
I and 10 are made of a synthetic material, charged with carbon particles to strengthen its stability to ultraviolet and improve the receptivity of solar radiation.

 Depending on the case> it may be interesting to make the outer wall 3 or 101, transparent to solar radiation.

FIG. 4 shows a detail of the outlet connection of the manifold 10, by a connection head 110 with an internal nozzle 111 for connection to the circuit 112 of the main heat transfer fluid and an all 113 for connection to the circuit of the heat transfer fluid - auxiliary 114.

 This text 110 is preferably made of synthetic material by assembling the two parts 111, 113 and with spacers, etc., and the assembly can be stuck at the top of the collector 10.

 When the assembly of the sensor is carried out under the arrangement provided in FIG. 2, a flexible assembly is obtained in the form of a rope ladder. This realization made in the factory is particularly interesting because as the materials are relatively flexible the sensor can be rolled up, which considerably facilitates handling and transport. For mounting the sensors, simply unroll the sensor and spread it out in the space provided; The sensor grouping mode is not the only one that is possible. We can also plan to group several sensors or sensor parts according to Figure 2, flat and stack them.

 In the sensor according to FIG. 2, it is particularly important that the tubes 1 which are placed in parallel, remain effectively parallel, and are not moved by the wind or by any other mechanical action.

For this, it is advantageous to provide a spacer member 12 such as that shown in FIG. 5. This member includes housings 121 which each time receive the tubes 1.

 FIG. 6 shows the installation of a sensor according to FIG. 2, on a terraced roof 13 of a building, equipped with the installation according to the invention. The sensor formed by collectors 102 11 and parallel tubes I, is preferably placed on a metal plate 14 which itself rests on a sheet of insulating material 15. This sheet of insulating material 15 can be provided not only on the horizontal surface from the terrace but it can also go up along the sides.

 Finally, the plate 14 may include supports 141 serving to maintain the tubes 1 in a correct position.

 The installation according to the invention is preferably intended to supply domestic hot water and hot heating water. This hot heating water is stored in large capacity storage tanks, from which the heating circuit draws heat. Under the same conditions, during hot periods, especially in hot countries, the installation according to the invention can be used alternately for the supply of frigories for air conditioning and calories for heating, in particular of sanitary battens.

 To supply frigories, the installation is operated overnight by circulating the heat transfer fluid through the sensor. As all of the peripheral surface of the tubes 1 (and possibly of the collectors 10, 11) radiates, there is a relatively large heat exchange which makes it possible to recover a large quantity of frigories, overnight.

 The frigories thus taken by the sensor are stored by the heat transfer fluid in a storage tank, from which the air conditioning installation draws during the day.

 The sensor according to the invention is particularly advantageous for this alternating operation for heating and air conditioning. Indeed, unlike a sensor working with a greenhouse effect, the operation is different depending on whether the sensor works as a receiver or as a heat emitter.

 When the sensor operates as a receiver, the apparent surface of the tubes I, that is to say the surface corresponding to the diameter of the tube multiplied by the length, is the large surface. On the other hand, when the sensor operates as an emitter, it is the whole of the peripheral surface, that is to say an area equal to T times the previous surface.

 This difference is particularly interesting in the conditions of use mentioned above because the nights are shorter than the days. In addition, the temperature gradient is also less. Moreover, in certain cases, to increase the efficiency of the installation in frigories it may be interesting to circulate the heat transfer fluid with a higher flow rate for the operation as a calorifier (recovery of frigories) than for the operation in sensor calories.

 It is also possible to use the auxiliary heat transfer fluid alone or in combination with the main heat transfer fluid to promote the emission of heat towards the interior by circulating these two fluids.

 FIGS. 3A, 3B show a manifold 10, the two walls 101, 102 of which are connected by a single spacer 105. In fact, as the tubes 1 are fixed on the orifices 106, 107, these connections keep the spacing of the walls apart 101, 102, a single spacer may suffice. Other solutions are possible with spacers following generators, helical, continuous or discontinuous, etc.

 According to a particularly advantageous embodiment, tubes 1, 10 are made of ethylene propylene diene monomer EPDM which is particularly resistant to ultraviolet rays and which can advantageously be loaded with carbon particles.

Claims (6)

 10) Installation with solar collector and circulation of heat transfer fluid between the collector and These storage means, installation characterized in that the collector consists of a tube (1), comprising an interior wall (2) and an exterior wall (3 ), the inner wall defining an inner enclosure (21) and the outer wall (3) defining with the inner wall (2) an outer enclosure (31), the inner enclosure (21) forming a path for the main heat transfer fluid and External enclosure (31) a path for the auxiliary heat transfer fluid, the two walls (2, 3) of the tube being interconnected (4) to form a mechanically integral assembly respecting the spacing of the two walls (2, 3).  20) Installation according to claim 1, characterized in that the outer wall (3) is transparent.  30) Installations according to claim 1, characterized in that the walls (2, 3) of the tube are made of ethylene-propylene-monomer charged with carbon particles. 40) Installation according to claim 1, characterized in that the sensor consists of a set of tubes (1) connected in parallel between an inlet manifold and an outlet manifold (10, 11) also with double wall.  50) A method of manufacturing a sensor installation according to any one of claims 1 to 4, characterized in that double-walled tubes are made, with the diameter These tubes of the sensor itself (1) and of the collectors (10, 11), these coaxial holes (106, 107) are made in the inner wall (102) and the outer wall (101) These tubes intended to constitute the collectors, the outer wall (101) is cut along a generator (108) passing through the holes (107), the tubes (1) are put in place, first fixing the end before the inner walls (2) in the holes (106) then, after positioning and fixing, this outer wall (3) is fixed in the corresponding hole (107) and the cutout (108) is closed. 60) Method according to claim 5, characterized in that the fixing is done by gluing or vulcanization.