WO2009034191A2

WO2009034191A2 - Heat recovery apparatus

Info

Publication number: WO2009034191A2
Application number: PCT/EP2008/062252
Authority: WO
Inventors: Wim De Graeve
Original assignee: Energy Products Group Nv
Priority date: 2007-09-14
Filing date: 2008-09-15
Publication date: 2009-03-19
Also published as: WO2009034191A3

Abstract

The present invention is related to an apparatus for recovering heat from a heated fluid, the apparatus comprising an area surrounded by an inner surface, wherein an active infra red radiation producing layer (4) is present on at least a part of said inner surface, the active layer being in heat-conductive contact with a container (1, 10) adapted to contain or circulate said heated fluid, and wherein an object (6,12) is present inside said area, said object being arranged to be heated by the radiation produced by said active layer and by reflected radiation coming off the inner surface. According to an embodiment, said inner surface is formed by an IR-emitting panel and a parabolic mirror facing said panel, whereby said object is a tube running along the focus line of said mirror. The invention is equally related to a lighting device arranged to recuperate heat produced by lamps.

Description

HEAT RECOVERY APPARATUS

Field of the invention

[0001] The present invention relates to apparatuses for heat recovery.

State of the art [0002] Document FR2683919 shows a structure comprising an active layer which comprises carbon, zirconium grains, and an organometallic component such as Yterbium. A heater is disclosed comprising such an active layer in combination with glass panels and electrodes and arranged as a heating device for indoor heating. The active layer is obtained by mixing the components with water and thus preparing a paste, which is applied to a glass plate and subsequently dried in an oven. Infra red- heating panels which are on the market today, e.g. from Energy Products (www.energyproducts.nl) comprise a similarly prepared active layer in combination with a glass panel and activated by electrodes. The active layer may further comprise metal oxides. The specific composition of the active layer defines the characteristic of the heating device. The layer is ^λactive' or ^λinfra red radiation producing' in that it produces IR-radiation when heated, through photon emission of some of the components (metal oxides) , and regulation of said emission by other components (e.g. Yterbium) . Other infra-red heating devices, such as e.g. described in FR2712380 use a similar active layer heated by a heating fluid circulating in tubes .

Aims of the invention

[0003] The present invention aims to provide apparatuses which use radiation heat produced by active layers as described above, for the recovery of heat produced by a primary heat source.

Summary of the invention

[0004] The invention is related to apparatuses as disclosed in the appended claims. In an apparatus according to the invention, an active infra red radiation producing material is arranged to recover heat from a primary heat source, for example wasted steam or water from a power plant. According to a specific embodiment, the active layer is used to recover heat produced by lamps. [0005] According to one embodiment, the apparatus comprises a radiation heat emitting panel comprising an active IR-producing layer in heat conductive contact with a heat exchanger arranged to contain or circulate said heated fluid, the apparatus further comprising a parabolic mirror, facing said panel, said mirror extending along a longitudinal focus line and having parabolic sections taken perpendicularly to said focus line, said focus line passing through the focal points of said parabolic sections. Along the focus line, a secondary tube may be present, arranged to contain or circulate a fluid which is to be heated by the radiation heat produced by the emitting panel.

[0006] According to another embodiment, the apparatus comprises a radiation heat emitting panel comprising an active IR-producing layer in heat conductive contact with a heat exchanger arranged to contain or circulate said heated fluid, the apparatus further comprising one or more parabolic mirrors, facing said panel, said mirror (s) being (a) circumferential parabolic mirror (s) . A secondary tube may run through the focal point (s) of said one or more parabolic mirrors.

[0007] A transparent layer is preferably present on top of the active layer, so that the IR-radiation is emitted through said transparent layer. The material of this transparent layer is ideally has good thermal isolation properties so that the flux of heat through this material is slow (to minimize heat loss by conduction) . An example of a suitable material is glass.

[0008] Further preferred embodiments are disclosed in combinations of the independent claims with one or more of the claims dependent thereon.

Short description of the drawings

[0009] Fig. 1 represents a first embodiment of the invention, being an apparatus with a tubular container. [0010] Fig. 2 represents a second embodiment, an apparatus equipped with a parabolic mirror.

[0011] Fig. 3a and 3b show test setups of apparatuses with a parabolic mirror according to the invention . [0012] Fig. 4 represents a third embodiment, equipped with a set of circumferential parabolic mirrors.

[0013] Fig. 5 shows an embodiment involving a light fitting.

Detailed description of the invention

[0014] The invention is related to an apparatus for recovering heat from a heating medium, being a heated fluid (gas or liquid) , the apparatus comprising an area surrounded by an inner surface, i.e. a fully enclosed or at least circumferentially enclosed area, wherein an active infra red radiation producing layer is present on at least a part of said inner surface, the active layer being in heat-conductive contact with a container adapted to comprise or conduct said heated fluid, and wherein an object is present inside said area, said object being arranged to be heated by the radiation produced by said active layer and by reflected radiation coming off the inner surface. The object can be a tube for containing or circulating a secondary fluid which is to be heated or it can be a solar cell. The heating medium itself can be heated inside or outside the container. The construction of the container is adapted to the conditions of the heating medium towards temperature, pressure, flux, chemical properties, etc....

[0015] Figure 1 shows an apparatus according to a first embodiment. The apparatus comprises a container in the form of the space 1 between two concentric elongated tubes 2 and 3. The space 1 is adapted to contain or conduct a heated fluid, such as water or steam. On the inside of the inner tube 2, an active IR producing layer 4 is present. It is preferably a layer comprising different active components such as conductive elements, metal-oxides (such as zirconium oxide) , binder material and local radiation absorber material (such as crystals) . Layer 4 can be an active layer with a composition and method of application as known in the art of IR-heating panels, see previous paragraph. The active layer 4 is in heat- conductive contact with the inner surface of the space 1, so that heat from a heating fluid can be transported to the active layer so that this layer produces IR radiation heat. The active layer may further be in contact with a layer 5 of IR-emitting material which is transparent to IR- radiation, the layer 5 being provided on top of the active layer, i.e. on the inner surface of the active layer so that the IR radiation is emitted through said transparent layer 5. For instance for infrared radiation with a wavelength between 6000 and 14000 nm and a surface temperature around 100⁰C ceramic materials like for instance glass can be used for the layer 5.

[0016] Through the transparent layer 5, IR-heat is emitted and heats up a secondary tube 6 directly and through reflected radiation coming off the interior surface. The secondary tube 6 is preferably placed in the centre of the inner tube 2 and may be arranged to contain or circulate a secondary fluid, heated by the emitted radiation, thereby recovering heat from the primary fluid contained or circulating in the tube 1. In stead of a secondary tube, a (preferably) centrally placed solar cell may be used as the heated object. The solar cell is preferably a concentrator solar cell.

[0017] An insulating layer 7 may be present around the whole or a part of the space 1 so that the heat losses trough convection are minimized and the ratio radiation versus conduction/convection is optimized.

[0018] Variations of the embodiment of figure 1 are possible : for example, the apparatus may have other shapes than the one shown (e.g. elliptical or rectangular), or the active layer 4 may be present on a part of the inner surface .

[0019] Figure 2 shows a second embodiment, wherein the active layer 4 is provided on a flat glass plate 5, the active layer being in heat-conductive contact with the container having the form of a heat exchanger 10 comprising tubes in which a primary fluid circulates, e.g. low temperature steam or water (100⁰C - 150⁰C), being wasted by power stations. The materials of the active layer and glass plate can be similar to known similar combinations known in electric IR-heating panels, for example. According to this embodiment, the transparent sheet material 5 and active layer 4 may be used to increase the temperature of another medium by concentrating the radiation in the focus point of a parabolic mirror 11, its concave side facing the emitting panel 4,5. The mirror is extending along a longitudinal axis (called focus line) 13 and has parabolic sections taken perpendicularly to said focus line, which passes through the focal points of said parabolic sections. Preferably, the section of the mirror taken at any point along the focus line has the same parabolic shape (i.e. the mirror is an elongated half-open- cylinder-like shape) . [0020] In this embodiment, the inner surface of said area cited above is formed by the IR-emitting plate (4,5) and the reflecting surface (the concave side) of the parabolic mirror 11, while a secondary tube 12 is present in (i.e. essentially concentrically with) the focus line of the parabolic mirror. The primary fluid is used to heat up the active layer 4. For example, the layer 4 and transparent layer 5 may reach a temperature between 80⁰C and 130°C, and will emit infrared radiation. This infrared radiation is concentrated in the focus line 13 of the parabolic mirror 11, by direct radiation to the focus line, and by reflection of radiation on the mirror surface. The secondary tube 12 can be a black (i.e. non-reflective) tube, and is arranged to contain or circulate a secondary fluid (e.g. oil, steam) . By concentrating the emitted infrared rays, the temperature of the secondary fluid in the tube can be raised to temperatures which are much higher than the temperature of the primary fluid. As such, part of the energy in the lost and wasted primary medium can be recuperated, because the energy in the secondary medium is put on a higher temperature level, and can be re- used. An insulation layer 7 may be present in this embodiment as well. Instead of a tube 12, one or more solar cells may be arranged along or in the vicinity of the focus line. Fig.3a illustrates a test apparatus with a parabolic mirror in combination with a secondary tube, and Fig.3b illustrates a test apparatus with solar vacuum tubes. These tubes also are put in the focus line of a parabolic mirror. Three tubes are shown in combination with three parabolic mirrors respectively. [0021] Figure 4 shows a third embodiment (front and plan view) , wherein a flat active IR producing layer 4 is provided on a glass plate 5, and heated by a tube-type heat exchanger 10. One or more circumferential parabolic mirrors 20 are arranged with their concave side towards the IR emitting surface. The inside surface of each of the mirrors is a circumferential paraboloid so that each mirror together with the active layer and glass plate, forms an enclosed area defined above. A tube 21 runs through the focal points 22 of the parabolic mirrors and may contain or transport a secondary fluid which is to be heated. Alternatively, a solar cell (e.g. a concentrator solar cell) is placed in each of the focal points 22. The heat produced by the active layer is concentrated in the focal point of the parabolic mirrors and can thereby heat up a secondary fluid circulating in the tube 21. An insulating layer 7 may be present as in the previous embodiment. Variations can be imagined whereby a plurality of mirrors is arranged, for example connected by a network of secondary tubes running through the focal points of the mirrors.

[0022] In any of the embodiments described above, the active layer 4 can be a layer wherein granulated IR- transparent emitting material, e.g. glass particles are mixed with the active components (metal oxides, absorbers, crystals) .

[0023] Variations to the embodiments of figures 2 and 4 are possible. The shape of the mirror may be other than parabolic or the secondary tube or the solar cell may be placed in a location other than the focus line or focal point. The shape of the IR-emitting plate formed by the active layer 4 and glass layer 5 may differ from a flat panel shape. [0024] According to another embodiment, an apparatus is provided for recovering heat produced by lamps. Light modules, such as bulbs and TL-lamps are generating heat. This heat is considered as loss. Imagine a light module as shown in Fig. 5. Lamps 30 are being heated up. This heat is accumulated within the light fitting 31. By making use of this lost heat by means of an active IR-producing layer 32 on the sheet of the fitting, the mechanical heat can be transformed into infrared radiation. [0025] The inner surface of the fitting is covered with an active layer possibly mixed with granulated IR transparent emitting material as described above. The active layer (with or without the granulated emitting material) is applied as a coating on the inner surface of the fitting. As such infrared radiation is being emitted within an interesting range of the IR-spectrum (say 6000 nm till 14000 nm) .

[0026] The invention is thus related to a lighting device, comprising one or more lamps (e.g. TL lamps 30), mounted in a light fitting, in other words a housing 31 which can be attached to a ceiling or wall, said housing having an exterior surface facing the space which is to be illuminated by the lamps, and wherein an active IR producing layer 32 in the sense described above is attached to said exterior surface. The active material provides radiation through the heating up of the active layer, the heat being provided by the lamps. In this way, heat produced by the lamps can be recuperated.

Claims

1. An apparatus for recovering heat from a heated fluid, the apparatus comprising an area surrounded by an inner surface, wherein an active infra red radiation producing layer (4) is present on at least a part of said inner surface, the active layer being in heat-conductive contact with a container (1, 10) adapted to contain or circulate said heated fluid, and wherein an object (6,12) is present inside said area, said object being arranged to be heated by the radiation produced by said active layer and by reflected radiation coming off the inner surface.

2. The apparatus according to claim 1, further comprising on top of said active layer (4), an IR- transparent layer (5) .

3. The apparatus according to claim 1 or 2, wherein said object is a tube (6) arranged to contain or circulate a secondary fluid which is to be heated.

4. The apparatus according to claim 1 or 2, wherein said object is a solar cell.

5. The apparatus according to any one of claims 1 to 4, wherein said container is formed by the space (1) between two essentially concentric tubes (2,3), an inner tube (2) and an outer tube (3), and whereby said area on which an active layer (4) is present is the inner area of the inner tube.

6. The apparatus according to claim 5, wherein said object is a tube (6) placed essentially concentrically with the inner tube (2) .

7. The apparatus according to any one of claims 1 to 4, comprising a radiation heat emitting panel comprising an active IR-producing layer (4) in heat conductive contact with a heat exchanger (10) arranged to contain or circulate said heated fluid, the apparatus further comprising a parabolic mirror (11), facing said panel, said mirror extending along a longitudinal focus line (13) and having parabolic sections taken perpendicularly to said focus line, said focus line passing through the focal points of said parabolic sections .

8. The apparatus according to claim 7, wherein a longitudinal tube (12) is arranged essentially concentrically with respect to said focus line.

9. The apparatus according to any one of claims 1 to 4, comprising a radiation heat emitting panel comprising an active IR-producing layer (4) in heat conductive contact with a heat exchanger (10) arranged to contain or circulate said heated fluid, the apparatus further comprising one or more parabolic mirrors (20), facing said panel, said mirror (s) being (a) circumferential parabolic mirror (s) .

10. The apparatus according to claim 9, wherein a tube (21) runs through the focal point (s) (22) of said one or more parabolic mirrors (20) .

11. A lighting device, comprising one or more lamps (30), mounted in a housing (31) which can be attached to a ceiling or wall, said housing having an exterior surface facing the space which is to be illuminated by the lamps, and wherein an active IR- producing layer (32) is present on said exterior surface.