WO2003098094A1

WO2003098094A1 - Thermoinsulating system

Info

Publication number: WO2003098094A1
Application number: PCT/IT2003/000295
Authority: WO
Inventors: Paolo Manini; Pierattilio Di Gregorio
Original assignee: Saes Getters S.P.A.
Priority date: 2002-05-21
Filing date: 2003-05-19
Publication date: 2003-11-27
Also published as: ITMI20021093A1; ITMI20021093A0; AU2003234065A1

Abstract

The present invention relates to a thermo-insulating system comprising a plurality of evacuated panels (1;4;5) each of which comprises a flexible envelope (2) made of one or more barrier sheets at the inside of which there is placed an inorganic or polymeric, discontinuous or porous filling material (3). Said evacuated panels (1; 4; 5) all identical one to another, can be arranged side-by-side so as to form as a whole a substantially tubular body.

Description

"THERMQΓNSULATΓNG SYSTEM"

The present invention relates to the thermal insulation of cylindrical or tubular bodies and in particular to a thermo-insulating system adapted for insulating such bodies.

Evacuated thermo-insulating devices in the form of planar panels are well known, and are increasingly used in all the fields where the thermal insulation of substantial parallelepipedal bodies is required. As examples of applications of these panels mention can be made of the walls of domestic and industrial refrigerators, of the beverages vending machines or of the containers for isothermal transportation, such as of drugs or chilly and deep-frozen foods. Applications of these panels in the field of building and in the car industry are also under study.

As it is known, an evacuated panel is formed of an envelope at the inside of which there is a filling material under vacuum. The purpose of the envelope is of preventing (or reducing as much as possible) the inlet of atmospheric gases within the panel, so as to keep a vacuum level compatible with the thermal insulation level required by the application. To this aim the envelope is made of so-called "barrier" sheets, characterized by a permeability towards gases as low as possible, that can be formed of a single component but more usually are multi-layers of different components. In the case of multi-layers the "barrier" effect is afforded by one of the component layers, whereas the other layers generally have functions of mechanical support and protection of the barrier layer.

The filling material has mainly the function of keeping apart the two opposite faces of the. envelope of the evacuated panel and must have a porous or discontinuous inner structure, so that its pores or interstices can be evacuated to accomplish the heat insulating function. This material can be either inorganic, such as powdered silica, glass fibers, aerogels, diatomaceous earth, etc.; or organic, such as rigid foams of polyurethane or polystyrene, either in the form of boards or powders. Since the permeation of traces of atmospheric gases within the panels is unavoidable in practice, these panels also contain in almost any cases one or more materials (generally referred to as getter materials) capable of sorbing traces of these gases, thus keeping the pressure within the panel at the desired values.

However, these planar thermo-insulating panels are unsuitable to achieve the insulation of cylindrical or tubular bodies, such as the Dewars or isothermal bottles, or the conduits used for transportation of oil in the artic regions.

This drawback is overcome by using the panels described in the international patent applications WO 02/02986 and WO 02/02987 in the name of the present applicant. The first application describes an evacuated panel of the above described type, that have features of flexibility thanks to the particular ratio between its thickness and the bending radius of the side wall of the curved body to be insulated and thereby can be wound around the walls of said body.

The second above-mentioned application also relates to an evacuated panel in which however the flexibility is due to the structure of the filling material. This latter is formed of at least two thin boards of an open cell polymeric foam, laying one over the other and free to slide one with respect to the other. This way, the total thickness of the panel allows to have an efficient insulation and in addition it is made possible to bend the panel while preventing the same from breaking.

However, an important drawback of this type of panels consists in the risk that the envelope, necessarily made from extremely fragile materials, tears or cracks, such as during winding, thus giving rise to the passage of atmospheric gases into the inside of the panel. Obviously such a passage would definitely endanger the efficiency of the panel, nullifying its characteristics of thermal insulation. The risk of cracking is higher whenever the insulating panel is applied externally and on sight, but it is present also when the insulation is placed in an inner space such as in the case of boilers or fittings used for feeding cryogenic liquids to medical apparatuses or the like. In these cases the envelope can in fact become damaged during the positioning of the panel in the inner space and the damage caused is even worse owing to the impossibility of replacing the useless panel. It is therefore an object of the present invention that of providing a thermo- insulating system that is free from such drawbacks. This object is achieved by means of a thermo-insulating system the main features of which are specified in the first claim and other features are specified in the subsequent claims. A first advantage of the thenno-insulating system according to the present invention consists in the fact that a possible break in the envelope of one of the' panels does not jeopardize the thermal insulation features of the whole system, but only involves a reduction of these features.

Additional advantages and characteristics of the tliermo-insulating system according to the present invention will clearly appear to those skilled in the art from the following detailed description of some embodiments thereof with reference to the annexed drawings in which: figure 1 shows a plan top view' of an evacuated panel for obtaining the thermo-insulating system according to a first embodiment of the invention; figure 2 shows a perspective view of an evacuated panel for obtaining the thermo-insulating system according to a second embodiment of the invention; figure 3 is a cross-section view of a thermo-insulating system made with the panels of figure 1 or figure 2; figure 4 shows a perspective view of an evacuated panel for the preparation of a thermo-insulating system according to a third embodiment of the invention; and

- figure 5 shows a thermo-insulating system made with panels of figure 4. With reference to the drawings, it is seen that the thermo-insulating system according to the 'present invention is formed of a plurality of evacuated panels , each of which comprises as already known a flexible envelope, made of one or more barrier sheets, at the inside of which there is placed an inorganic or polymeric, discontinuous or porous filling material. Said panels are all of identical shape and can be arranged side-by-side so as to form in a whole a substantially tubular body which thereby can be used for the thermal insulation of cylindrical or tubular bodies, such as e.g. the Dewars or isothermal bottles.

Making in particular reference to figure 1, there is seen that an evacuated panel 1, usable for making a thermo-insulating system according to a first embodiment of the invention, comprises an envelope 2 at the inside of which there 5 is a filling material 3 of any type, e.g. polyurethane, which is formed with an annular shape. The envelope 2 can for example be formed of two sheets with a central hole and welded to each other all around the inner and the outer perimeter of said annular shape, thereby forming an inner flange 2a and an outer flange 2b of the envelope.

10 h case the filling material 3 is formed as a board of open cell polyurethane, this is advantageously tapered at the inner circumference of the annular shape.

In an alternative embodiment, illustrated in figure 2, the evacuated panels 4 which form the thermo-insulating system according to the present invention are made in the same identical way as illustrated above, but all show a crescent shape,

15. in other words each of them form one half of an annular shape.

In figure 3 it is shown how a multiplicity of evacuated panels 1 or 4 can be used to form a thermo-insulating system according to the present invention, h particular, the panels are stacked one onto another around the body to be insulated or around the channel where the fluid to be kept at constant temperature flows. In

20 the case shown in the drawing, the panels are inserted between the two walls of a fitting for feeding cryogenic liquids to a medical apparatus.

In case of crescent-shaped panels 4, as illustrated in figure 2, they are coupled together in pairs in the final thermo-insulating system and then arranged in overlapping positions. Such overlapping is suitably arranged in such a way that

25 the lines joining the various pairs of panels are out of coincidence.

Figure 4 shows another example of evacuated panel that can be used for preparing a thermo-insulating system according to the invention. Such an evacuated panel, 5, is also formed with an envelope at the inside of which there is sealed a filling material of whichever known type. In this case, the shape of the

30 filling material, and consequently also of the panel in its whole is that of a trapezoidal prism, i.e. a prism having the two bases shaped as a trapezium. The envelope of such a panel can be obtained by welding together two rectangular barrier sheets, thus forming an outer flange 6 along four faces of the panel.

As shown in figure 5, a thermo-insulating system can be obtained by assembling together, e.g., eight panels of the type represented in figure 4. This system can be applied both at the inside of the double wall of a conduit, and at the outside about the walls of a cylindrical body to be insulated. This way, the accidental cracking of one of the panels during the installation or the life of the system does not jeopardize the features of thermal insulation of the system itself.

Claims

1. A thermo-insulatmg system characterized by comprising a plurality of evacuated panels (1; 4; 5) all being identically shaped, each of which comprises a flexible envelope (2) made with one or more barrier sheets at the inside of which there is placed an inorganic or polymeric, discontinuous or porous filling material (3), said panels (1; 4; 5) being arranged side-by-side so as to form in their whole a substantially tubular body.

2. A theraio-insulating system according to claim 1, characterized by the fact that each of said evacuated panels (1) is substantially of annular shape.

3. A thermo-insulating system according to claim 1, characterized by the fact that each of said evacuated panels (4) is substantially formed as a half of an annular shape.

4. A thermo-insulating system according to claim 1, characterized in that each of said evacuated panel (5) has substantially the shape of a trapezoidal prism.