GB2210963A - Construction and prefabricated component acting as a heat reservoir, heat exchanger and heat radiator - Google Patents

Description

1 2210963 " Construction and prefabricated component acting as a heat

reservoir, heat exchanger and heat radiator, its use and method for its manufacture " The invention relates to a construction, part of a construction or prefabricated component acting as a heat reservoir.

heat exchanger and/or heat radiator, which stores heat and transfers it to the space to be heated or away from it The invention further relates to use of such a construction, part of a construction or prefabricated component and method for its manufacture.

Conversion to electrical heating places quite particular de- mands on the heating systems to be used It should be pos- sible to combine electrical heating with existing heating installations based on liquid circulation in order to mini- mize both the costs of conversion and also the allergy and other drawbacks associated with conventional electrical heating In addition it should be possible to store heat produced by electricity, for instance in connection with the utilization of night-rate electricity, without using separate large storage tanks or masses The problem of the invention is thus how to discover a construction or prefab- ricated component acting as a heat reservoir, heat exchanger and/or heat radiator, which would effectively and without the aforesaid drawbacks store heat and transfer it further to the space which is to be heated.

In known heating systems, in which water is employed as the heat transfer medium, heat is transferred to the heating water for the living space by means of heat exchange from the hot water of the heating boiler, heating power station or district heating plant In these systems heat is stored solely in large water tanks arranged in conjunction with the heat exchange Also known for use in indirect heating of small buildings are storage heaters which are heated during night-time with cheap night-rate electricity and which during the day-time heat air or water circulated through the storage heater A storage heater of this type is a massive solid or tank of liquid of large size.

In respect of fixed constructions in connection with heating conductors the main subjects of attention have been only the strength, compactness and thermal insulation of the construc- tion and material In floors and other similar constructions, in which the indoor surface is covered or lined with e g.

tiles, natural stone, plastic or wood, ordinary finely-divided concrete has been used as the screed A traditional concrete screed of this sort generally consists of cement, water and an aggregate, which may be finely-divided sand or ordinary finely-ground stone From the point of view of heating tech- nology, however, the properties of these materials have been such that they in no way promote the heating occurring within the floor or other similar construction.

A purpose of the present invention is to provide a construc- tion, part of a construction or prefabricated component in- tended for spaces which are to be heated and acting as a heat reservoir, heat exchanger and/or heat radiator, by means of which the aforesaid drawbacks of heating systems according to the state of the art can be eliminated The invention has, then, principally the characteristics which are stated in the characterization section of the patent claims Thus it has been realized that by forming the constructions or parts of the constructions of or arranged in connection with the space to be heated from a material containing a mineral substance which stores and spreads heat well, and by arranging electric heating elements and/or ducts for a heating medium in said material or in connection therewith, it is possible to pro- vide a system which acts as a heat reservoir, heat exchanger and/or heat radiator and which does not need extra storage tanks or masses and which moreover does not require the water or other such heating system of the living space to be re- moved and completely replaced by an electric heating system.

The mineral substance gives the construction or prefabricated component good properties from the point of view of heating technology, so that the construction or prefabricated com- ponent takes up the heat given out by the heating elements of the electric heating and releases it again in a suitable manner The invention is thus based on the idea of locating the electric heating elements and/or ducts for a heating medium inside or in connection with a construction or pre- fabricated component the material of which consists to a substantial extent of a mineral substance which stores and spreads heat well and which is advantageously soapstone, magnesite, gypsum and/or a slag which is substantially free of voids.

By the construction, part of a construction or prefabricated component of the invention is meant, for instance, screed such as the concrete screed of a floor.

The mineral material which stores and spreads heat well used in the construction, part of a construction or prefabricated component of the invention can be soapstone, for instance Juuka Karevaara soapstone, which contains approx 40-50 % wt.

of talc Mg Si 4010 (OH)2, approx 40-50 % wt of magnesite Mg CO and approx 5-8 % wt Mg Al Si 01 (OH) The mineral sub- stance intended for the invention and which stores and spreads heat well can be in any form whatsoever, but it is advantageous to use it as a powder as the aggregate of a mass which is hardened and/or compressed Soapstone powder suitable for the invention is obtained, e g, in quantities of approx 3000 tons per annum as a byproduct of the pro- duction of Suomen Vuolukivi Oy (Nunnanlahti) when soapstone is worked Suitable types of magnesite are e g magnesite I and magnesite II (both Mg CO) based on a byproduct which is produced in connection with the manufacture of talc Mag- nesite is obtained, e g as a byproduct of the talc produc- duction of Myllykoski Oy (Luikonlahti) Gypsum is calcium sulphate dihydrate Ca SO 2 H O in powder form and it occurs both as a natural mineral and as a byproduct of inorganic process industries It is a porous material, but soft and can thus be pressed to a dense form, e g by the techniques of powder metallurgy.

The poor properties of magnesite, soapstone and gypsum are their softness and effect of retarding the hardening of con- crete and impairing its workability, which prevents their being used directly in powder form as the aggregate of such a hardening mass Important properties from the point of view of the invention are the density, specific heat and thermal conductivity of soapstone and magnesite The speci- fic heat of soapstone varies in the range 0 9-1 1 J/g K As 3 the density of soapstone, 2 98 kg/dm -, is relatively high, its heat capacity per unit volume is as high as in the range 3 o 2.68-3 28 k J/dm C.

The slag containing few or no voids essentially comprised in the material of the construction, part of a construction or prefabricated component according to the invention can be any slag produced as the byproduct of an iron refining pro- cess, such as blast-furnace slag, acid or basic steel slag or advantageously ferrochromium slag, which is e g compres- sed to eliminate voids Slag is formed on the surface of the molten refined iron, from where it is recovered, cooled and crushed to a suitable coarseness Advantageous ferrochromium slag contains 27-29 % wt silicon oxide, 23-28 % wt alumin- ium oxide, 22-27 % wt magnesium oxide, 3-8 % wt calcium oxide, 5-7 % wt chromium and 2-4 % wt iron It is not radioactive or water soluble, its p H is in the range 8 75- 8.9 and it is produced in Finland in quantities of approx.

240,000 T/A in connection with the manufacture of ferro- chromium.

Of the above-mentioned mineral substances which store and spread heat well the most advantageous is soapstone.

If necessary a metallic filler, e g copper machining chip- pings, can be added to the material in quantities of up to % in order to increase the heat capacity and thermal con- ductivity.

Depending on the desired properties and manufacturing re- quirements, the construction, part of a construction or pre- fabricated component of the invention can be a screed or a moulded or cast component A moulded component may be a mineral substance, such as magnesite, soapstone, gypsum and/ or a slag essentially free of voids which is compressed into a hard material by ordinary mechanical means or by the tech- niques of powder metallurgy The compression of the mineral substance by the techniques of powder metallurgy into the construction or prefabricated component of the invention is carried out with possible additives, such as binders and substances to reduce friction and pressure during compression, either without heating or with the aid of such heating as activates the binders and/or sinters the mineral substance concerned Pressing is advantageously carried out by first pressing a base layer of the mineral moulding mass, placing the electric heating element and/or the pipe or similar for the heat transfer medium on top of said layer, then covering the electric element and pipe with a fresh layer of mineral moulding mass and finally pressing the latter layer into a dense mass surrounding the electric element and/or the pipe.

The embodiment according to which the construction or pre- fabricated component is moulded by the techniques of powder metallurgy is based on the realization that the said mineral substances, which are generally very porous and disadvantage- ous from the point of view of heating technology, can be moulded by the techniques of powder metallurgy into products which are essentially free of voids and have very advantage- ous properties from the point of view of heating technology.

The construction, part of a construction or prefabricated component can also consist of an ordinary screed or casting compound containing said mineral substance, which stores and spreads heat well, a suitable binder and possibly other ag- gregate and auxiliary substances Such a compound can, de- pending on the desired properties, contain approx 5-50 % wt.

advantageously approx 5-30 % wt of binder, which is advan- tageously cement The amount of the mineral substance, which stores and spreads heat well, is 10-90 % wt advantageously 10-70 % wt of the total amount of material For a casting compound a mineral material such as sand, which improves the casting properties and strengthens the final product, can be present in an amount of 10-90 % wt, advantageously 30-80 % wt When cement is used as the binder, water is generally added in an amount of approx 2-60 % wt, advantageously approx 2-40 % wt.

By the construction, part of a construction or prefabricated component acting as a heat reservoir, heat exchanger and/or heat radiator is meant any construction, part of a construc- tion or prefabricated component which is arranged in a space to be heated or in the surface or surfaces thereof and within which or in connection with which are arranged one or more electric heating elements and/or one or more ducts for a heat transfer medium Said duct can be intended for various media, such as water, oil or air.

The construction according to the invention can be a separate heat exchanger which, owing to the good thermal properties of the mineral material used, fits into a small space and does not involve high installation costs The separate heat exchan- ger can advantageously be constructed from blocks pressed or cast from a mineral material which stores and conducts heat well, with the electric heating elements within said blocks being connected to electric feed cables running between the blocks or on the surface of the heat exchanger and with the ducts in the blocks for the heat transfer medium being con- nected together to form a duct which is connected to the heating system of the living space and into which a suitable pipe for the heat transfer medium has or can be pushed A separate heat exchanger of this kind is suitable e g for effectively storing electric heat and transfering it to the heating liquid circulation system of the space being heated.

When the construction or prefabricated component of the in- vention is employed in interior spaces, it can be e g a radiator or building board, a panel board or industrialized building component which forms an integrated part of the walls, floor and/or ceiling of the living space The construction or prefabricated element can be a product which does not contain electric heating elements or ducts and is only arranged near them to transmit the heat, but advantage- ously one or more electric heating elements and/or one or more through ducts for a heating medium such as water and/ or air run within the material of the construction or prefabricated component Prefabricated components can be con- nected together to form a larger entity, such as a heating floor, heating wall, heating ceiling or heating stairs, which stores, exchanges and radiates the heat of the living space In this case the electric heating elements are connected in parallel directly to an electric feed cable, the voltage of which has been reduced to a safe level After in- stallation of the construction or prefabricated components a pipe of suitable size and thermal conductivity is threaded through the ducts for the heating medium and connected to the water or other such heating system of the space or spaces being heated In general it can be said that the larger the heat storage and exchange element of the living space, the smaller the temperature variations, and thus the smaller the drawbacks connected with electric heating, and the larger the heat storage and exchange capacity of the system.

The casting or pressing into the final product can be carried out either on the building site, e g as a heating screed, or else in a factory producing prefabricated building components.

The surface decoration can be applied in situ or at the fac- tory by painting, wallpapering, covering with glass-fibre fab- ric, by solid dyeing, tiling or lining with natural stone or wood One application is in cow sheds, where e g heating floors can be constructed to utilize night-rate electricity.

Such floors are advantageously insulated from the ground by thermal insulation, such as sheets of styrox Wall elements for interior spaces are advantageously of sheet form and as such installable can be installed by hand on the site.

Instead of the electric heating elements and/or ducts for a heat transfer medium being embedded in material containing a mineral substance which stores and spreads heat well, the joints between components made of the material can be made in such a manner that electric heating elements and/or ducts for a heat transfer medium can be embedded in the joints, so that they run inside the seams between the components and are thus outwardly protected at the same time as they heat both components Such designs are suitable for very small or narrow components, in which the heat has time to spread into the entire component before passing into the spacing which is to be heated - The construction, part of a construction or prefabricated component according to another embodiment of the invention forms a heated, e g ice-free, paving or surfacing for out- door spaces In this case the components can be arranged in rows essentially parallel with an electric feed cable and be connected, advantageously in parallel, to said feed cable So that the electric voltage does not constitute a danger to the surroundings, the voltage is advantageously reduced by means of a transformer The construction or com- ponent, made either on site or in a factory, advantageously comprises a base layer, which is of a thermally insulating material, a middle layer, which is of a material containing a mineral substance which stores and exchanges heat well and in which are embedded one or more electric heating ele- ments and/or one or more ducts for a heating medium, and a top layer forming an appropriate surface, such as paving, cladding or artificial grass Advantageous outdoor applica- tions are ice-free sidewalks, pedestrian areas, bus stops, railway platforms, playing grounds, sports fields, skating rinks, substrates for greenhouses and nursery hotbeds, etc.

When an ice-free sidewalk, pedestrian area, bus-stop or rail- way platform is constructed, water from melted ice easily collects The problems caused by this can be solved by plac- ing the rows formed by the components together with their electric feed cables in essentially parallel planes which are inclined so that the water formed by the melted ice runs off into gutters and/or drainpipes embedded in the lines of intersection of the inclined surfaces These gutters and/or drainpipes are advantageously heated by electric heating elements connected, in the same circuit The dimensions of components to form a base construction for pedestrian traffic are, for instance, of the order of 600 x 1200 x 200 mm including the insulation.

1 O The heat storing, exchanging and radiating construction or components according to an embodiment intended for outdoor spaces can be used, for instance, for a playing field - skating rink combination, the principle of which differs from the principle of the embodiments described above in that at times the electric heating elements are used to heat the field as a playing field and at other times the ducts for a heat transfer medium are used to cool the field to pro- vide a skating rink During the periods of cooling a medium used in liquid/gas refrigeration, such as ammonia, freon/ frigen or brine, is circulated in the duct.

In preparing a base construction for larger outdoor spaces, such as football fields, it is advantageous to proceed by making the components block by block on the site, so that each block has its own electric feed cable, to which the electric heating elements of the components are connected, and possibly its own pipework for a heat transfer medium comprising either all or a selected part of the components of the block Manufacture on the site is carried out either by casting or else advantageously by first laying an insu- lating layer over the foundation of the field, then spread- ing on top of the insulating layer a mass containing a mineral material which stores and spreads heat well and compacting said mass to a suitable density, laying the electric heating elements and/or pipes for a heat transfer medium on top of the compacted mass, covering the heating elements and/or pipes with a suitably thick layer of a mass contain- ing a mineral material which stores and spreads heat well and finally compacting the upper layer of the mass to form a hard and durable surface Finally, the surface can be covered by a suitable surfacing, such as artifical grass, as determined by the intended use.

A base construction for greenhouses, nursery beds and hot- beds can be made either by casting or by packing a material 1 1 according to the invention around electric heating elements and/or a duct for a heat transfer medium so as to form a base layer, which is advantageously located on top of an insulating layer The growing compound, in which a thermo- -stat can be located, is then spread on top of the base layer After planting, the temperature of the growing com- pound can be adjusted and the most advantageous heating form employed.

The construction or prefabricated component acting as a heat reservoir, heat exchanger and heat radiator of the present invention can be operated by a time-switched circuit, a tem- perature-switched circuit, manually, and/or a night-rate electricity circuit The electric circuit and the circula- tion of the heat exchange medium can be programme controlled according to the price and availability of electricity as well as the need for heating, e g with the aid of a micro- processor The elements can if necessary be connected in parallel or series with the aid of fixed switching devices or switching devices at the end of the electric cable It is, however, advantageous to use a voltage reduced to a safe level by a transformer and to connect the heating elements of the components in parallel, whereby the electric heating is both safe and less exposed to failure of the individual electric heating elements Since the construction or prefab- ricated component of the invention is an excellent electri- cal insulator, it is advantageous to integrate it partly or entirely with other electrical functions, such as lighting, socket outlets etc The prefabricated components of the in- vention can also be connected together, for instance util- izing a lighting rail in the living space.

The invention also relates to a method for the manufacture on a continuous basis of construction or prefabricated com- ponent acting as a heat reservoir, heat exchanger and/or heat radiator.

According to one embodiment manufacture is carried out on a belt so that first a base casting compound is evenly spread on the belt using a vibratory hopper or suchlike feeding de- vice The base casting compound forms a layer underneath the electric heating elements and/or duct for a heating medium, the thickness of this layer being determined by the heat capacity and heating speed which the construction or prefab- ricated component is to have.

After spreading of the base casting compound it is smoothed either by means of a roller, in which case the ribbon re- mains intact after compacting, or else by a press which me- chanically compresses successive parts of the ribbon and advantageously at the same time cuts them into base pieces the size of the final component.

Next the smoothed ribbon of compound is compacted by chemi- cal and dynamic means, for instance by addition of chemicals which promote compacting and by using vibration Then the electric heating elements and/or pipes for heating medium are installed in the same plane on top of the compacted base casting compound.

In the case that the electric heating elements and pipes for a heating medium are installed one above the other, after the installation of one of them a further stage of spreading, smoothing, and chemical and dynamic compacting of a filler casting compound is carried out before installing the other one of them In this way both the electric heating elements and the pipes for a heating medium are entirely surrounded by a thermal mass according to the invention.

Then further is carried out spreading, mechanical smoothing, out chemical and dynamic compacting of a surface casting corn- pound, and if the smoothing has been carried out by means of rollers, cutting of the ribbon into components.

Finally the unhardened or semi-hardened components are con- veyed to a rack where conditions are such as to promote har- dening Hardening can advantageously be accelerated by con- necting the heating elements to electricity from electric rails arranged in connection with the store.

The construction or prefabricated component of the invention can also be manufactured by means of casting in moulds, in which case the electric heating element and/or pipe for a heating medium is first installed inside the mould (at a suitable distance from each other) The thermal screed or thermal compound of the invention is then poured into the mould After the pouring stage follows chemical compacting, mechanical compression e g using vibration, and finally hardening of the screed or compound, advantageously using the installed electric heating element.

In the following the invention is described in greater de- tail with reference to the figures, in which:

Figure 1 shows a basic heat exchanger according to one em- bodiment of the invention; Figure 2 shows a construction according to another embodi- ment of the invention which is intended for indoor and out- door spaces; Figure 3 shows a floor construction according to an embodi- ment of invention in which the electric heating elements and heating pipes are separate; Figure 4 shows a system of prefabricated components according to an embodiment of the invention and intended for outdoor constructions; Figure 5 shows an electric heating system according to an embodiment of the invention, in which the components are in- tegrated into the floor, wall and ceiling of the living space; Figure 6 shows a construction according to an embodiment of the invention, in which replacement air is led between an outer decorative panel and the basic wall construction; Figure 7 shows components according to the invention arrang- ed until the surface of a sports field;

Figure 8 shows a soil heating system for a greenhouse accor- ding to an embodiment of the invention; Figure 9 shows continuous manufacture of prefabricated com- ponents according to the invention.

In Figure 1 is shown a construction according to the present invention which mainly represents a separate heat exchanger 1, which consists of block-shaped components 2, which are joined together by mortar to form a heat exchanger according to the invention The mortar 3 is also advantageously a dense mass according to the invention containing a mineral substance which stores and spreads heat well The blocks 2 are manufactured by casting or pressing their mass around an electric heating element 4 so that said element 4 is em- bedded in the block 2 In the manufacturing stage of blocks 2 one or more mould pipes-pass through the mould thereby creating one or more holes in the block In connection with the laying of blocks 2 before joining with mortar pipes 5 and 6 for a heat transfer medium are passed through said hole or holes and are thus entirely surrounded by mineral material and remain after the joining of the blocks with mor- tar, forming channels for the heating system running through the rows formed by the blocks In the heat exchanger shown in Figure 1 the pipes 5 are intended for heating water and the separate pipes 6 for air which is to be heated.

The heating elements 4 are connected to electric feed cables 7 which are suitably located with respect to the heat ex- changer The heating elements 4 are advantageously connected in parallel, in which case the electric feed cables 7 are twin cables In this way the failure of a single element 4 does not break the electric circuit and thereby cut off the entire heating If it is considered that the high mains voltage would constitute a danger, the electric feed cable 7 is advantageously connected to a transformer (not shown in the Figure) which reduces the voltage to a safe level.

The heat exchanger acording to the invention shown in Figure 1 consists of two vertical rows of block components 2, but it is obvious that rows can be added in the width and depth directions and in the vertical direction of the block com- ponents It is, of course, possible to manufacture a heat exchanger also in one single piece, e g by casting In addition the heat exchanger according to the invention can advantageously be connected to an appropriate microprocessor which adjusts the heat according to the need for heating and economic resources.

Figure 2 shows a construction acting as a heat reservoir, heat exchanger and heat radiator according to another embodi- ment of the invention, so that on the left-hand side of the broken line is shown a construction 11 intended for indoor spaces and/or spaces where a hard base is required, and on the right-hand side of the broken line is shown a construc- tion intended for outdoor spaces and/or spaces where a soft base is required On the surface of the construction there are slabs 8, which are e g natural stone slabs or ceramic tiles, or a soft base 8 ', which is e g felt or artifical grass Below the surface layer is a layer 9 which acts as a heat reservoir, heat exchanger and heat radiator and con- sists of a mass, e g screed, containing a mineral material which stores and spreads heat well In layer 9 is embedded an electric heating element 4 and a duct 5 for a heat trans- fer medium In a construction manufactured on site for an outdoor space pipes cannot easily be connected in series so as to produce a tight system, so that a pipe or tube of smaller diameter is pushed inside the actual pipe 5 to form a reliably tight part of the heat transfer network.

The layer 9 is manufactured either by casting or as a screed, in whichcase in addition to a mineral material which stores and spreads heat well it also contains binder and possibly other typical components of casting or screed compositions, or else by compressing a dry mass, in which case in addition to a mineral material which stores and spreads heat well the mass advantageously contains a dry binder, a substance to re- duce friction during compression and possibly other typical additives Any mineral material whatsoever-that stores and spreads heat well can be used in the layer 9 The mass of layer 9 can also contain strengthening constructions such as steel netting or reinforcing rods Below layer 9 is fur- ther an insulating layer 10, which is for instance foamed plastics such as expanded polystyrene, which has a density 3 of approx 25 kg/m Such an insulating layer prevents heat from escaping underneath the structure, dampens the dynamic vibration, shocks and loading caused by traffic, and also acts as a protective and strengthening part of the con- struction.

Prefabricated components for interior surfaces of a space to be heated can also be made so that a heating element or duct runs along the join between the components in the manner shown by Figure 3 In embodiment a components 9 are instal- led on top of a layer of insulation 10 and shaped so that an electric heating element 4 fits between them This is achieved by step profiling of the join between components so that they fit together to form a groove of suitable size for electric heating element 4 in one of the inside folds of the step of the join In this case the electric heating elements can either be pre-installed or for installation on the building site In embodiment b components 9 which store and spread heat well are shown installed on top of a layer of insulation so that space is left between them both for an electric heating element 4 and a duct 5 for a heat transfer medium On the left-hand side is shown a joint with a square profile in which an electric heating element 4 and a duct 5 for a heat transfer medium are embedded in the jointing material, which is advantageously a mass according to the present invention which stores and spreads heat well On the right-hand side is shown a V-joint with an electric heating element 4 and pipe 5 for a heat transfer medium embedded in the jointing compound, which advantageously contains a material which stores and spreads heat well The embodiment b is especially advantageous when the electric heating ele- ment and heating pipes are installed on the building site.

The embodiments shown in Figure 3 are best suited when the components 9 are sufficiently small or narrow, so that the electric heating elements in the joints heat the whole com- ponent before the heat passes out of the component into the space being heated.

Prefabricated components can be installed mechanically in the manner shown in Figure 4 to form a base construction for pedestrian and cycle traffic, with components 11 which store, exchange and radiate heat being in rows essentially parallel with an electric feed cable 7 and connected with the aid of short cables and plugs to said electric feed cables 7 Also shown in Figure 4 is a see-through view of the components, in which can be seen the electrical heating elements 4 and the pipes 5 for a heat transfer medium which pass through the component 11 The components 11 are advantageously manu- factured so that they have ready-formed ducts when they are laid in rows as shown in Figure 4 and the pipes 5 are pushed into the ducts of the components 11 so that a tight network is formed by the pipes 5 for a heat transfer medium It is advantageous to arrange the rows formed by the components 11 essentially parallel to the electric feed cables 7, as is shown in Figure 4 The levels can slope, e g from the cen- tre outwards, so that water from melted ice runs off into gutters 12, which are heated by electric heating elements 13 which are connected in the same circuit.

The heat storing, exchanging and radiating construction or prefabricated component of the invention can also advantage- ously be integrated as a part the interior surface entity of a living space, as is shown in Figure 5 In it a complete heat storing, exchanging and radiating system of prefabri- cated components 15 is integrated into the ceiling, right- hand wall and floor of a living space 14 The heat exchange capacity of system 15 with the inside air of the space 14 is very large because of the large surface.

The ceiling and floor constructions of the system of heating components 15 consist of two components and the wall con- struction consists of one component, said components being connected together via an electric feed cable 7 running in the direction of their lengths Said electric feed cable 7 runs through the ceiling, wall and floor constructions and and to it are connected the electric heating elements 4 in said surfaces Also other electrical appliances, such as the light shown in the figure, can be connected to the electric feed cable 7.

Under the window on the rear wall of the living space shown in Figure 5 are arranged two components connected in parallel which extend along the rear wall of the living space and in the vertical direction up to the lower edge of the window.

The duct for a heat transfer medium is a pipe 5 which runs through the floor components and which together with a hot 1 9 water tank 16 and one or more hot-water radiators 17 forms a water heating network The embodiment of Figure 5, having cast floor heating, is very suitable e g for heating cow sheds.

Since the heat produced by a heating system of this type passes rapidly into the air of the living space, the tem- perature difference required between the heat radiators and the air is very small This reduces convection air currents and thus the quantity of dust in the air In addition the hydrolyzing effect of electric heating radiators on dust is eliminated Thus it can be said that the dust allergy, odour problems and other respiratory problems are substantially diminished as a result of the heating construction or com- ponents of the present invention.

Since the electric and water heating component of the inven- tion is essentially made of mineral material, it does not have ionizing parts nor does it form an electrostatic charge as in metal heat radiators Because of its electrically in- sulating properties accidents from electric shock are effec- tively eliminated This is also affected by the voltage be- ing reduced to a safe level with the aid of a transformer.

Its low temperature also prevents, for instance, children burning their fingers Moreover, the system is reliable in operation, since the electric heating elements are advan- tageously connected in parallel so that failure of one ele- ment does not interrupt the electric heating current.

Exterior wall constructions according to two embodiments of the present invention are shown in Figures 6 a and 6 b Figure 6 a shows a timber-framed and Figure 6 b a concrete front wall construction or prefabricated component The external space is on the left-hand side and on the right-hand side is the heated space to which heat is transferred by convection and radiation The construction comprises, starting from the external space, an exterior cladding 36, the load-bearing structure of the wall 37 (only in the embodiment of Figure 6 a), a layer of thermal insulation 38 and a-structural part 39 of said insulating layer, which part in the embodiment of Figure 6 b is a load-bearing concrete wall These layers are in accordance with the state of the art and their order can be changed In accordance with the invention, however, a component 42 which stores and spreads heat well has been utilized so that between said component 42 and the inside structural part of the insulating layer or the load-bearing concrete wall 39 there is an air space 41, to which replacement air is led via a duct 40 Owing to the convection pro- duced in said empty space 41 by heating component 42, said replacement air, which has possibly been pre-heated and/or' cleaned, flows through duct 40 into the space 41 between the insulating layer 38 and its inside structure part or the load-bearing inside wall 39 and the heating component 42 and then flows upwards in the manner indicated by the arrows un- til it passes out of the aperture between said heating com- ponent 42 and the ceiling into the space to be heated In this manner the replacement air mixes in the top part of the space being heated with the air rising up over the side of the heating component 42 which faces the room, bringing suitably warm replacement air into the space being heated.

The solutions shownin Figures 6 a and 6 b are inventive only in the event that the heating components 42 of the present invention are employed.

Figure 7 shows a football field 18 and the upper part of the figure shows how components 19 according to the invention are arranged in two rows in the direction of the longitudin- ally bisected football field 18 Electric heating elements 4 are arranged individually for each component and connected in parallel, so that failure of one element will not stop the heating The elements 4 are then connected to twin feed cables 7, which obtain a suitable voltage from a transformer Pipework 5 for heat transfer water is arranged so that the pipe snakes and passes through each component 19 twice in the lateral direction of the field 18 Since pipe 5 also makes a loop outside the field, it is possible to break the pipe in the loop and connect the pipe to other loops so that only the desired part of field 18 is heated.

The football field components 19 of the invention are advan- tageously made on the site, so that a hollow is formed at thle intended site of the component in which is spread if re- quired a thermally insulating layer and on top of that a first layer of a composition according to the invention con- taining a mineral material which stores and spreads heat well After smoothing and compacting of said composition, an electric heating element and/or a heating/cooling pipe is laid on top of said composition Then on top of the electric heating element and/or heating/cooling pipe a second layer of said composition or of a said type of composition used in the invention is laid, and spread and pressed over and around the heating element and/or pipe If the electric heating elements and pipes-are to be one above the other, then between their installation there is an addition stage of spreading and compacting of the composition On top of the second or equivalent layer still a third layer according to the invention is spread using a composition with proper- ties which are the same as those of the first and second layers or else slightly modified e g so that thermal con- ductivity is given relatively greater weight than heat capacity On top of the smoothed and compressed third layer is then laid a suitable covering for a football field, for instance grass, artificial grass or football-field felt.

The football field represented by Figure 7, like heated football fields in general, can be used as a heat exchanger, so that the field is heated at nights by cheap night-rate electricity and during daytime by a heat-transfer medium 4 heated at night In winter the duct for a heat-transfer medium can be used to cool the field Cooling too can, due to the heat-storing composition of the invention, be arranged so that it is carried out at night using cheap night-rate electricity.

Figure 8 represents the use of a construction according to the invention in order to achieve soil heating in a green- house For many plants it is advantageous if the growing bed can be warmed by a few degrees Heating cables 4 and/ or hot-water pipes 5 are installed in the growing area row, platform, bed or table in a layer 9 of a material essentially containing a mineral substance which stores and spreads heat well, located below soil layer 21 Said layer 9 is either powder, which is pressed as dense as possible around heating organs 4 and/or 5 so as to achieve good heat capacity and thermal conductivity, or else a concrete com- position according to the invention, which is compacted to eliminate voids before hardening The thickness of the heat storing and spreading layer is e g 3-5 cm for con- tinuous heating and e g 10-15 cm for night heating Below the heating layer there is advantageously a layer of ther- mal insulation.

The construction or prefabricated component acting as a heat reservoir, heat exchanger and/or heat radiator according to the invention can either be used so that the heat produced by the electric heating elements is transferred with the aid of the heat conducting mineral material to the heat-transfer medium, which is connected to a larger tank, e g a hotwater tank, in which it is stored for later use, or else so that with the aid of one or more electric heating elements heat is stored in a heat exchanger of the invention and which possesses a large mass, in which it is stored until later transported away with the aid of one or more heat transfer media.

Figure 9 represents a method for continuous manufacture from a casting compound of prefabricated components according to the invention First a base casting compound is spread from a vibratory hopper 24 onto a belt 23 Said base casting com- pound 25 is then smoothed with the aid of a roller 26 and compacted by chemical and dynamic means Compacting is pro- moted e g by the addition of compacting chemicals with the aid of a spray device 27 and by moving the belt with the aid of a vibrator 28, whereby air bubbles disappear from the compound.

Electric heating elements 4 and/or pipes 5 for a heating medium are installed on top of the compacted base casting compound Then a surface casting compound is spread on top from another vibratory hopper 29 Then follows a new smooth- ing stage with the aid of a roller 30 and a new chemical and dynamic compacting with the aid of a spray device 27 and a vibrator 32 Finally the dense construction according to the invention is cut into components 33 with the aid of a blade 34.

The ready cut components 33 are finally conveyed to racks 35, where they are heated by connecting their electric heat- ing elements to electric rails or electric feed cables 7.

Claims (29)

Claims

1 A construction, part of a construction or prefabricated component acting as a heat reservoir, heat exchanger and/or heat radiator, which stores heat and transfers it to the space to be heated or away from it, characterized in that it is formed of a mass containing essentially a mineral material which stores and spreads heat well, within which or in connection with which are arranged one or more elec- tric heating elements and/or one or more ducts for a heat transfer medium.

2 A construction, part of a construction or prefabricated component according to Claim 1, characterized in that said mineral material is soapstone, magnesite, gypsum and/or slag, advantageously soapstone.

3 A construction, part of a construction or prefabricated component according to Claim 1 or 2, characterized in that said mass is a moulded mass which is pressed into a con- struction or prefabricated component containing few or no voids.

4 A construction, part of a construction or prefabricated component according to Claim 3, characterized in that said moulded mass is a moulded mass formed by the techniques of powder metallurgy and containing besides said mineral material possibly also a binder, a material to reduce friction during pressing and/or other additives.

A construction, part of a construction or prefabricated component according to Claims 1 or 2, characterized in that said mass is a screed or casting compound, which is laid or cast so as to be as dense as possible, for instance using air-elimination chemicals and vibrators.

6 A construction, part of a construction or prefabricated component according to Claim 5, characterized in that a material suitable as the binder of mineral material, advan- tageously cement, is used as the binder of said screed or casting compound.

7 A construction, part of a construction or prefabricated component according to Claim 5 or 6, characterized in that part of said screed or casting compound consists of an ag- gregate, advantageously sand, which improves the strength and workability of the mass and possibly other casting com- pound additives.

8 A construction, part of a construction or prefabricated component according to any of the preceding claims, charac- terized in that electric heating elements are embedded in a mass essentially containing a mineral material which stores and spreads heat well, and are connected in parallel and the heating voltage is advantageously reduced by means of a transformer to a safe level.

9 A construction, part of a construction or prefabricated component according to any of the preceding claims, charac- terized in that it is a heat exchanger ( 1) transferring electric heat to a medium, the material of which is said mass ( 4) and in the material of which are embedded one or more electric heating elements and one or more ducts for a heat-transfer medium, which ducts can be for instance liquid ducts ( 5) or gas ducts ( 6).

A construction, part of a construction or prefabricated component according to any of Claims 1-8, characterized in that it is in the form of an ordinary room-heating radiator ( 17) or similar.

11 A construction, part of a construction or prefabricated component according to any of Claims 1-8, characterized in that it is a sheet or panel ( 15) which contains one or more electric heating elements ( 4) and/or ducts ( 5) for a heat- transfer medium and which is an integrated part of the wall, floor or ceiling entity of an indoor living space ( 14) and which forms a heating system comprising a heating surface which is substantially larger than the heating surface of the heating radiator ( 17).

12 A construction, part of a construction or prefabricated component according to Claim 11, characterized in that in said sheet or panel ( 15) of the heating system there are ducts ( 5) for a heating medium, advantageously water, and said ducts are connected to the medium, advantageously water, heating system of the living space, for instance to a hot water tank ( 16) and radiators ( 17).

13 A construction, part of a construction or prefabricated component according to any of Claims 1-8, characterized in that it is in the form of components ( 11) intended for out- door spaces, in which components in addition to a layer ( 9) formed of a material essentially containing a mineral sub- stance which stores and spreads heat well there is also on the side that can be heated a surface layer ( 8), which is for instance natural stone or ceramic tiles joined to each other, wood or a surfacing intended for a soft base as for instance grass, and on the side which is not heated if neces- sary a layer of thermal insulation ( 10), which is advantage- ously foamed plastics such as expanded polystyrene.

14 Use of a construction, part of a construction or pre- fabricated component according to Claim 13 as a base con- struction for vehicular traffic, pedestrian traffic or liv- ing spaces so that at least the heated components containing electric heating elements ( 4) are located in rows essential- ly parallel with an electric feed cable ( 7) and connected to said electric feed cable ( 7), advantageously in parallel.

Use according to Claim 14, characterized in that an ice-free roadway or sidewalk, pedestrian area, bus-stop or railway platform or other suchlike is formed by setting rows formed of heated components ( 11) together with their elec- tric feed cables ( 7) in essentially parallel planes which are inclined so that the water formed by melting runs off into gutters or drains heated by electric heating elements connected in the same circuit.

16 Use according to Claim 14, characterized in that ice- free steps are formed so the heated components form the treads of the steps, whereon said components are connected to electric feed cables running in the direction of the steps and next to the steps.

17 Use according to Claim 14, characterized in that seat heating for an outdoor grandstand is formed so that the electric heating components are fixed on top of or under- neath the benches, whereon they are connected by separate cables to electric feed cables running in the direction of the benches and next to them.

18 Use according to Claim 14, characterized in that the base of a sports field ( 17) or suchlike is formed so that at least one layer is the aforesaid material essentially con- taining a mineral substance which stores and spreads heat well, in which material are embedded one or more electric heating elements ( 4) and one or more ducts ( 5) for a heating/cooling medium.

19 Use according to Claim 18, characterized in that the base of a sports field ( 17) or suchlike is constructed of several components ( 19) so that electric heating element ( 4) and pipe ( 5) for a heating/cooling medium can be connected to heat the desired part of the field.

Use according to Claims 18 or 19, characterized in that heat from cheap night-rate electricity is transferred by elements ( 19) to a heat transfer medium which stores said heat in a heat transfer medium tank and uses it during the daytime or else cheap night-rate electricity is used for heating during night-time and during daytime heating by cheap water heating obtained from fossil fuels, and in addi- tion the pipework for a heat transfer medium is possibly used in winter to cool the field as a skating rink.

21 Use of a construction, part of a construction or pre- fabricated component according to Claim 11, characterized in that the construction, part of a construction or prefabri- cated component ( 42) in question is installed at a distance from the interior surface ( 39) of an outer wall of a build- ing and replacement air is led into the empty space ( 41) thereby formed so that the heat of the construction or pre- fabricated component ( 42) causes convection of the replace- ment air upwards into said empty space until at the desired height it flows heated through a slit or similar above the construction or prefabricated component into the space which is to be heated.

22 Use of a construction, part of a construction or pre- fabricated component according to any of Claims 1-8 as a heatable growing bed.

23 A method for manufacture continuously on an industrial scale of a prefabricated component acting as a heat reser- voir, heat exchanger and/or heat radiator, characterized in that a) a base casting compound containing essentially a mineral material which stores and spreads heat well is spread on a belt, b) the base casting compound on the belt is smoothed and possibly cut by a mechanical smoothing device, c) possible compacting of the smoothed base casting com- pound is carried out, d) electric heating elements and/or ducts for a heating medium are installed on top of the base casting compound, e) a surface casting compound containing essentially a mineral material which stores and spreads heat well is spread on top of the electric heating elements and/or ducts for a heating medium, f) the surface casting compound is smoothed and possibly cut by a mechanical smoothing device, g) final compacting of the surface casting compound and at the same time of the entire mass of the prefabricated compon- ent is carried out, h) the mass is cut, if this has not been done in connec- tion with smoothing, so as to form prefabricated components containing one or more electric heating elements and/or one or more ducts for a heating medium, and i) the prefabricated components are hardened, advantage- ously by connecting electricity to their electric heating elements.

24 A method according to Claim 23, characterized in that it is continuous.

A method according to claim 23, characterized in that it is a batch mould casting technique in which the hardening reaction is either chemical and/or is supplemented by a com- pression stage carried out in the moulds.

26 A method according to Claim 23, characterized in that said mineral material which stores and spreads heat well is soapstone, magnesite, gypsum and/or slag.

27 A method according to Claim 26, characterized in that the base and/or surface casting compound is concrete which advantageously contains in addition to a mineral material which stores and spreads heat well also an essentially harder mineral material.

28 A method according to any of Claims 25-27, characterized in that said mechanical smoothing device in stages b) and/or f) is a roller or a press which cuts the side edges.

29 A method according to any of Claims 25-27, characterized in that said compacting of stages c) and g) is carried out by adding compacting chemicals, for instance foam elimination chemicals, and/or by moving the belt with a vibrator.

A method according to any of Claims 25-27, characterized in that said spreading of stages a) and/or e) is carried out with the aid of a vibratory hopper.

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