AU2006201774A1

AU2006201774A1 - Radiative-conductive heat exchanger

Info

Publication number: AU2006201774A1
Application number: AU2006201774A
Authority: AU
Inventors: Dorin Preda
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-04-28
Filing date: 2006-04-28
Publication date: 2006-11-23
Anticipated expiration: 2026-04-28
Also published as: AU2006201774B2

Description

00 P/00/009 28/5/9 1 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION To 6 ec 4o 4e- p To V I 6\1 ovlz 'W5090Zj-3l Invention Title: RADIATIVE-CONDUCTIVE HEAT EXCHANGER k 2

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The following is a description of the invention and of a few ways of use for it.

00 The field of the invention is the heat exchange through radiation between a radiative source or a radiative sink and a gas, in particular air. Most of the applications of this invention relate to solar energy devices. The present complete specification discloses new S applications for permeable cover solar collectors and extends their field of application to cooling the air, not only heating it.

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IND

In order for solar energy to be competitive with the fossil fuel energy sources, it has to be economical, that is to deliver energy at a price comparable with the fossil fuel sources.

This calls for both high energy efficiency and reduced cost of manufacturing of the new devices. In this patent application the main designs are described (the ones found to be highly economical). However, other designs using the permeable cover are possible, as one skilled in the art can develop.

From the theoretical engineering point of view, the applications according to this patent application belong to the field of the heat exchangers, as they absorb or emit radiation and in turn give away or receive heat through conduction. This justifies the title of the patent application.

This is a device capable of simultaneously exchanging energy as radiation with other bodies around it (including the sun or the night sky) and compensating for the gain or loss of radiative energy by heating or cooling the air that passes through it. The purpose of the radiative-conductive heat exchanger is to heat or cool the air; a suitable form of energy exchange through radiation is chosen to accomplish said purpose. The permeable cover is attached to a support structure at a distance from a reverse layer so that a plenum is created between said permeable cover and said reverse layer from which heated or cooled air flows to outside said plenum. By 'reverse layer' is meant a material boundary, like the ground or a roof or a sheeting material that is tightly connected on its sides with the sides of the permeable cover so that a plenum is created between them.

IND 3

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SAn application of the radiative-conductive heat exchanger is the cooling of air. If this device is exposed to the sky during the night it will emit more energy through radiation 0 C than it will absorb from the night sky. As a result, the permeable cover will cool down to a temperature smaller than the temperature of the air flowing through it, and therefore the device will cool down the air. Such a device installed on the roof of a building can be used during the cold seasons to warm up the air with solar energy, while during the summer nights it can cool down the air, creating a more pleasant environment inside the building.

In one version of this invention, the air of changed temperature is used inside said JO plenum. One example is a foldable enclosure (representing the plenum of the radiativeconductive heat exchanger) made out of a black permeable cover oriented towards the Equator and provided with means which can blow the air out from said enclosure. The means could consist of a fan actuated for example by an electric motor powered by a photovoltaic panel. Optionally, a transparent and rain impermeable cover is installed above the black permeable cover. Such an enclosure heated with solar energy can rise the temperature of the air by 20 degrees Celsius even during a cloudy day: therefore it can be used as temporary or emergency shelter for field hospitals, disaster-relief and humanitarian purpose, camps, etc. Other applications for these enclosures are dryers for agricultural, forestry or industrial products. It is to be observed that an usual tent structure heats much less the air inside it because the air is not made to flow through its side exposed to solar radiation, therefore the heat produced on the outside of the cover just creates convection currents and is lost to the atmosphere.

In another version of this invention, the support structure of the radiative-conductive heat exchanger consists of vertical poles and a horizontal network of metallic cables or beams to which said permeable cover is attached. Unlike in the tent-type embodiment of above, this structure is more resistant to mechanical stress and especially to strong winds. In case said permeable cover is placed close to the horizontal, weights can be attached under or above the permeable cover to diminish the vertical movements induced by wind. If the N 4 permeable cover is installed in a close to horizontal position, a carriage can travel along Ssaid cables or beams and above said permeable cover to do maintenance work.

00 In another version of this invention, said reverse layer of the radiative-conductive heat exchanger has a corrugated shape and plays also the role of the support structure because the permeable cover is stretched between the ridges of the reverse layer and creates said plenum with the troughs of the reverse layer. This embodiment is useful in case of the Sroofs covered with corrugated metal sheeting, whereas the air of changed temperature is drawn from each such trough through a common collector conduit running across them.

In another version of this invention, thermal insulation is placed under said reverse layer Sto diminish the unwanted gains or loses of heat from the air in the plenum. This arrangement is particularly useful in case of the solar collectors placed on the roof where the roofing material constitutes said reverse layer.

The air heated with solar energy in the radiative-conductive heat exchanger described above can be used for burning fossil fuel. This has two advantages: (S It diminishes the consumption of fossil fuel with a proportion approximated by the rate between the temperature of the solar heated air and the temperature of the fossil fuel burnout gases.

SIt improves the burning of heavy fossil fuels It is well known that almost all our energy (thermal, electrical, chemical) originates in burning of fossil fuels. As the solar collectors described in this patent application can rise the temperature of the air by about 60 degrees Celsius and the burnout gases of a power plant have a temperature of about 1200 degrees Celsius, it results that preheating the air with solar energy can diminish with about 1/20 the consumption of fossil fuels.

However, other industrial processes that use large amounts of fossil fuel (for example the 2 dryers) need only about 80 0 C gases, therefore the solar air heaters can reduce the consumption of fossil fuel by about

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In another version of this invention, said permeable cover collects the radiative heat of a heat source it surrounds (for example an engine or the flame of a burner), transforms that radiation into heat and transfers the heat to the air that passes through the permeable 00 cover and towards said heat source. This arrangement is suitable for different burners that have the purpose of heating an air stream, and not their surroundings. Another benefit of this version of the invention is that the air surrounding the permeable cover will be free from the smoke, smell and the heat generated by said source. This way the burner rooms and the engine rooms of factories, ships, etc can become more pleasant environments.

The particular developments will not be considered limiting to the scope of the invention; Io other embodiments of the invention can be developed by those skilled in the art starting from the above.

Reference will now be made to the drawings whereas: FIG. 1 represents a vertical cross-section through a radiative-conductive heat exchanger placed on a roof.

I FIG 2 represents a vertical cross-section through a radiative-conductive heat exchanger placed on the ground FIG 3 represents a vertical cross-section through a radiative-conductive heat exchanger where the air is used inside it FIG 4 represents a vertical cross-section through a radiative-conductive heat exchanger of a tent-like structure.

FIG 5 represents a vertical cross-section through a radiative-conductive heat exchanger installed on a corrugated roof.

FIG 6 represents a cross-section through a radiative-conductive heat exchanger that surrounds a flame Referring now to FIG 1, it can be seen a radiative-conductive heat exchanger installed on a roof 1 or on another inclined surface and being used as a solar collector and'or a night

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air cooler. The permeable cover 2 creates a plenum 3 with the roof I which has Sunderneath the thermal insulation 4. The heated or cooled air is drawn through the collection conduit 5 by the fan 6 and delivered to the place of use through the delivery conduit 7. A rainwater drain 8 is provided to discard the water that would reach the 57 collection conduit Referring now to FIG 2, it can be seen a large radiative-conductive heat exchanger (being used as a solar collector and/or a night air cooler) and installed on a reverse layer 1 that is generally horizontal. The permeable cover 2 is attached to the parallel beams 3 that are C supported by the vertical poles 4. A layer of thermal insulation 5 would be placed above the reverse layer 1. A carriage 6 would travel along the beams 3 and above the permeable cover 2 to do maintenance work. The air of changed temperature is drawn from the plenum 7.

Referring now to FIG 3, it can be seen a building having at least one wall I that may be thermally insulated and an area covered with a permeable cover 2 which is optionally covered with an impermeable cover 3, the air being blown out from the plenum 4 with the means 5 so that the air of changed temperature is used inside the plenum 4. For example, the plenum 4 of that building can be used as a drier room where the material to be dried is placed.

Referring now to FIG 4, it can be seen a tent-like structure having one side made out of a dark coloured permeable cover I oriented towards the Equator that is optionally covered by a transparent and impermeable cover 2, the air being blown out from the plenum 3 with the means 4, so that the air of changed temperature is used inside the plenum 3.

Preferably, the sides of the structure not made out of permeable cover 1 should be impermeable. The means 4 could be a fan actuated for example by an electric motor powered by a photovoltaic panel. Such a tent-like structure heated with solar energy can be used as a temporary shelter for humanitarian purpose, for camps, or even as driers.

N 7 Referring now to FIG 5 it can be seen a vertical cross-section through a corrugated roof 1 Shaving ridges 2 and troughs 3 onto which a radiative-conductive heat exchanger is C installed and consisting of the permeable and flexible cover 4 that is attached to the roof 1 with the screws 5 around its sides. The permeable cover 4 is stretched between the ridges S2 to which it also can be fixed in other parts of its area so that it does not move because of the wind. The permeable cover 4 crates plenums 6 with the troughs 3 from which the heated or cooled air is drawn through the thermally insulated conduit 7 that is tightly C connected to the permeable cover 4 and which sits across and onto the ridges 2.

Alternatively to the conduit 7, the heated or cooled air can be drawn from the plenums 6 10 with conduits penetrating the roof 1 at each trough 3, but this solution is less practical.

Thermal insulation 8 may be placed under the roof 1 to diminish the loses of heat.

Referring now to FIG 6 it can be seen a permeable cover I surrounding a flame 2 created by the fuel injected in the plenum 3 by the injector 4. The air 5 is heated when it passes through the permeable cover 1 that in turn was heated by the radiation emitted by the flame 2. The heated air Sparticipates in the burning process which generates the flame 2 and the exhaust gases 6 that exit the plenum 3.

Claims

1. A radiative-conductive heat exchanger comprising a permeable cover that can 00 exchange heat through radiation with the surrounding environment and can exchange heat through conduction with the air passing through it, said permeable cover being attached to a support structure at a distance from a reverse layer so that a plenum is created between them, heated or cooled air being extracted from said plenum.

S2. The radiative-conductive heat exchanger of claim 1 wherein said permeable cover is exposed to the sky during the night so that it is cooled by emitting through radiation more energy than it absorbs, therefore it can cool the air that flows through it.

3. The radiative-conductive heat exchanger of any of the previous claims wherein a transparent but impermeable cover is placed above said permeable cover, the air to be heated flowing from the space between the two covers through the permeable cover and into said plenum.

4. The radiative-conductive heat exchanger of any of the previous claims wherein S the place of use of the cooled or heated air is inside said plenum.

The radiative-conductive heat exchanger of claim 4 wherein said heat exchanger consists of a foldable structure that can be used as a tent.

6. The radiative-conductive heat exchanger of any of the previous claims wherein said support structure consists of a network of metallic cables or beams to which said permeable cover is attached.

7. The radiative-conductive heat exchanger of claim 6 wherein said network consists of parallel metallic cables or beams in a close to horizontal position which are supported by a plurality of vertical poles, so that a carriage can travel along said cables or beams and above said permeable cover to do maintenance work.

8. The radiative-conductive heat exchanger of any of the claims 1 or 2, wherein said reverse layer has a corrugated shape, so that said permeable cover is stretched between the ridges of the reverse layer and creates said plenum with the troughs of said reverse layer.

9. The radiative-conductive heat exchanger of any of the claims 1, 2, 6 or 8, wherein thermal insulation is placed underneath said reverse layer. IN 9 c

10. The radiative-conductive heat exchanger of any of the previous claims wherein Sthermal insulation is placed inside said plenum and above said reverse layer.

11. The radiative-conductive heat exchanger of any of the previous claims wherein C the air heated with solar energy is used for burning fossil fuel.

12. The radiative-conductive heat exchanger of claim 1, wherein said permeable cover surrounds a burner and collects the radiation emitted by said burner, transforms it into heat and transfers the heat to the air passing through said permeable cover towards Ci said burner where the air is used in the burning process.