The present invention relates to a method of heat-exchange, comprising advancing an energy-carrying medium in a channel system comprising lengths of mutually parallel channel parts, such as hose parts, and supporting said channel parts with the aid of a substantially sheet- or slab-like base element.

The invention also relates to an arrangement for carrying out the method.

The invention is intended primarily for application in the construction of artificially frozen ice-rinks or like playing areas, but can also be applied to produce all kinds of large heat-exchange surfaces, such as so-called heated floors, solar-energy collectors, etc..

In conventional methods of producing artificially frozen playing areas, steel pipes are cast in a concrete bed or anchored loosely in a gravel bed, and refrigerant, such as ammoniacal liquid, is caused to expand and evaporate. The energy required herefor is taken from the ambient surroundings of the pipes, therewith cooling the surround¬ ings.

Later solutions utilize indirect evaporation techniques, i.e. a frost-protected liquid is chilled with the aid, for instance, of ammonia or freon and is circulated in the channel system of the ice rink, pitch or like area concerned. The pipes used may be made of a plastics material. The plastic pipes are anchored in reinforcement netting or the like and are embedded or anchored in some other way, and then covered with gravel, such as to provide a cooling surface for the production of an artificially frozen ice-rink or like area.

According to one method of laying cooling pipes in gravel beds, there is first formed a layer of asphalt concrete which is provided with grooves on the outer surface thereof for accommodation of the cooling pipes. The cooling pipes, often in the form of hoses, are then placed in the grooves and surrounded or packed with sand, up to the level of the upper edge of the asphalt layer. The surface is covered with a

fibre fabric, for instance a geofabric, and a layer of gravel material is laid to a depth of about 50 mm, with the intention of preventing the hoses from moving out of the grooves as a result of linear expan¬ sion in summer time. The hoses are thus held in position by the weight of the gravel in combination with pressure distribution from the fibre fabric. The hoses placed in said asphalt grooves or in some other grooved material can also be covered with concrete, which anchors the hoses and protects the same against mechanical action and the effect of degrading UV-light. A construction of hoses in a grooved base material covered, for instance, with gravel or concrete can be used as a cooling surface for artificially frozen ice rinks, as a heated floor or as a solar energy collector on the ground, on a separate framework or on the roof of a building.

An analysis has shown that the following technical desiderata and considerations are common to such constructions:

Heat transfer from/to the undersurface of the construction should be screened with an insulating material, so as to direct heat transpor- tation from/to the hoses to a layer which essentially covers the outer layer of the construction.

The hoses should be densely packed, so as to achieve a large hose- surface area and therewith a more uniform distribution of temperature from/to said Burface layer and lower resistance to heat transportation through the walls of the hoses.

It should be relatively simple to anchor the hoses in conjunction with placing said hoses on the base element, since varying temperatures and solar radiation will result in an increase/decrease of the hose temperature, therewith causing the hoses to move prior to being finally anchored, by packing said hoses with an appropriate material.

The material packed around and over the hoses, up to the surface of the construction, should have a high thermal conductivity, so as to achieve the lowest possible temperature drop through said material. The material should also be in good contact with the outer surfaces of the hoses, so as to achieve the lowest possible resistance to the

tranβfer of heat to/from the hose walls.

The thermal mass of the covering material will influence the reaction rate in the construction when the thermal load from/to the surface of the construction varies. For instance, a decrease in the temperature of the refrigerant in the hoses of an artificially frozen ice rink, or an increase in the temperature of a heat carrier in a heated floor is considerably delayed with changed temperatures on the surface of the construction in proportion to the thickness of the covering layer and the total thermal mass.

The present invention relates, to a solution in which rational assembly incorporating a small number of mutually different components is integrated in a construction which includes screening insulation on the undersurface thereof, dense hose distribution, locking of hoses against longitudinal and vertical movement, low heat-transfer resis¬ tance from hoses to covering material and a low coeficient of thermal conductivity and low thermal mass of the covering material, said solution eliminating the drawbacks of known solutions and providing important advantages in the form, inter alia, of effective use of energy and good drainage.

The invention thus relates to a method of heat exchange in which an energy-carrying medium is advanced in a channel system comprising mutually parallel and adjacent channel parts, such as hose parts, and supporting said channel parts on essentially sheet or slab-like base members. The method is mainly characterized in that channel parts are carried and held by at least one pre-fabricated sheet of heat-insulat¬ ing material, such as so-called cellular plastic material, and in that said channel parts are laid-out in locking grooves formed in said sheet and, when applicable, having a width which is slightly smaller than the width of a channel part, in applicable cases the diameter of a channel part.

The invention also relates to a heat-exchanger arrangement in which the exchange of heat is effected by advancing an energy-carrying medium in a channel system comprising mutually parallel and adjacent channel parts, such as hose parts, supported by essentially sheet or

slab-like base parts. The arrangement is mainly characterized by at least one pre-fabricated sheet of heat-insulating material, such as so-called solar plastic material, for supporting channel parts, said Bheet including channel-part locking grooves which extend in the intended length direction of the channel parts and which, in ap¬ plicable cases, have a width which is preferably slightly smaller than the width of a channel part, when applicable places the diameter of the channel part.

The invention will now be described in more detail with reference to the accompanying drawings, in which

- Fig. 1 illustrates schematically part of a first embodiment of a channel part supporting sheet or slab, said sheet being seen from above; - Fig. 2 is a sectional view taken on the line A-A of Fig. 1;

- Fig. 3 illustrates schematically part of a second embodiment of a channel-part supporting sheet, or slab said sheet being seen from above;

- Fig. 4 is a sectional view taken on the line B-B in Fig. 3; - Fig. 5 is a schematic, vertical sectional view taken transversely to the longitudinal direction of the channel parts and shows a first embodiment of a heat-exchanger arrangement where sheets and channel parts are covered with a layer of moieture-retaining filler material; - Fig. 6 is a schematic, sectional view essentially similar to Fig. 1 and showing a second embodiment of a heat-exchanger arrangement where an upper ^" layer of discrete plates, for instance, concrete slabs, are disposed;

- Fig. 7 is a schematic sectional view essentially similar to Fig. 5 and showing a third embodiment of a heat-exchanger arrangement where concrete has been cast over sheets and channel parts;

- Fig. 8 is a schematic sectional view, essentially similar to Fig. 5, of a fourth embodiment of a heat-exchanger arrangement, where concrete has been cast over sheets and channel parts and where buttress-like reinforcements and screeding abutments are provided;

- Fig. 9 a-h illustrates schematically various vertical-sections of grooves formed in channel parts, certain of said grooves constituting locking grooves;

- Fig. 10 illustrates schematically the formation of locking grooves with the aid of studs which are shown in vertical section taken on the line C-C in Fig. 11;

- Fig. 11 illustrates the arrangement of Fig. 10; - Fig. 12 is a schematic, vertical sectional view taken transversely through the channel parts of a fifth heat-exchanger arrangement, where a concrete surface covering has been cast on site;

- Fig. 13 is a schematic, sectional view of a sixth heat-exchanger arrangement essentially similar to Fig. 12, where a concrete surface covering has been cast on site;

- Fig. 14 is a schematic, perspective view of a straight-edge arrangement operative to produce a patterned covering;

- Fig. 15 illustrates schematically and from above a seventh heat- exchanger arrangement where an inner floor is placed on sheets incorporating channel parts, the upper layer of the floor being removed in Fig. 15, however; and

- Fig. 16 is a sectional view of Fig.15, with the upper layer shown.

Fig. 1 illustrates a channel system 1 comprising a plurality of channel parts, such as hose parts. The channel parts are intended to convey an energy-carrying medium (not shown) and are supported on a pre¬ fabricated sheet or slab 2 of heat-insulating material, such as so- called cellular plastic material, which forms a channel-part supporting base member.

The illustrated arrangement also includes short channel-part locking grooves 3 incorporated in the sheet or slab 2. The width of respective locking grooves will preferably be slightly smaller than the width of a channel part, when appropriate the diameter of said channel part, as illustrated in Fig. 1. The supporting sheet or slab will preferably be made from a material which will as to provide a degree of resi¬ lience to the walls of the locking grooves, such that said grooves will open against a spring force when a channel part 1 is pressed thereinto, therewith holding the channel part to a certain extent.

Locking grooves of mutually different configurations are described hereinafter with reference to Fig. 9.

According to one preferred embodiment, the locking grooves are formed in channel-part support grooves 4. The grooves 4 are preferably comparatively wide. In the Fig. 1 embodiment, the grooves widen essentially from a bottom part 5, so that the upwardly facing mouth 6 of each groove will have a width in the order of twice the largest cross-dimension of a channel part, in this case the diameter of said channel part.

The embodiment illustrated in Fig. 1 thus comprises a sheet or slab 2 in which a plurality of essentially parallel supporting grooves 4 extend side-by-side between mutually opposing end walls 7, of which one is shown in Fig. 1, and a.t least one locking groove 3 is provided in each supporting groove 4 between said end walls. In the illustrated embodiment, the end walls 7 are configured as locking grooves in connection with said supporting grooves 4. Also shown are locking grooves 3 included in a transverse wall 8 in said supporting grooves, said wall 8 blocking said grooves, with the exception of the locking groove.

Similar to the Fig.l embodiment, the cross-sectional shape of the locking grooves conforms to the cross-sectional shape of the channel parts, therewith enabling water to be retained for a longer period of time between such locking grooves when a channel part is inserted into the locking grooves 3.

Figs. 3 and 4 illustrate an embodiment in which the channel parts 1 lie in a common supporting groove 4 between rim parts 4' which extend substantially parallel with the channel parts.

In many cases of several applications, such as in the case of artifici¬ ally frozen ice rinks for instance, a moisture-retaining filler material 9, such as sand, is appropriately placed around the channel parts in said grooves 4, as illustrated in Figs. 5 and 6. This material is intended to be substantially saturated with water, with the inten- tion of achieving good heat transfer between the channel parts and the surrounding medium or media. In such applications, the sheets or slabs are also preferably covered with a layer of moisture-retaining filler material 9. Grooves 4, such as the grooves 4 illustrated in

Fig. 9, a.-d), may also conceivably form locking grooves, Channel parts 1 are being intended to be held firmly, to some extent, in these grooves with the aid of preferably of fine-grain filler material. In this case, the locking grooves, at least at certain parts of the groove cross-section, will therefore be noticeably wider than the channel parts.

The embodiment illustrated in Fig. 6 includes discrete concrete slabs 9' which are laid on filler material 9 to form an upper covering.

The transportation of heat and water in the Fig. 5 and 6 embodiment will be described hereinafter.

In the Figs. 7 and 8 embodiments, concrete 10 is cast over the sheets or slabs 2 which support the channel parts 1. In the Fig. 7 embodiment, a relatively thick concrete layer has been cast, in order to achieve the requisite mechanical strength.

In order to achieve the requisite mechanical strength and anchorages between slabs 2 and concrete 10, the slabs can be provided with recesses 2' and/or promontories 2" which are respectively filled with or embedded in concrete, said recesses and/or promontories being disposed in a given pattern. This will enable a somewhat thinner concrete layer to be used. In the case of the Fig. 8 embodiment, concrete reinforcing buttresses 11 are used to form a pattern of thickenings 11 of concrete layer in the slabs or sheets, a substantial part of the thickenings being disposed in slab parts 12 between said grooves 4. Fig. 8 also shows that the slabs or sheets may include screeding abutment elements or straight-edges 13 which form an up- standing framework and which are intended to form abutments for coaction with strikers during a concrete casting operation and also to divide the concrete surface into smaller sections. The straight-edges 13 also form dilation joints which function to take-up movement in the concrete surface. The straight-edges or plates 13 can also be arranged adjacent edge parts of the slabs or sheets and. more centrally of said edge parts.

Fig. 9 illustrates various groove embodiments and shows the embodiments

a.-d) as examples of configurations in which a low thermally active mass is disposed between the pipes, while the embodiment e)-g) are examples of a channel-part locking where the groove has been expanded when pressing a channel part thereinto, in order to achieve long term locking of the channel part. The locking surfaces of the locking groove need only reach to about 60* of the diameter of the channel- part concerned, as in g). An example of densely packed channel-parts locked in respective locking grooves is shown in the illustration h).

Figs. 10 and 11 illustrate a slab or sheet embodiment in which studs 14 are operative to clamp channel parts firmly therebetween. The size, diameter, of the studs, can, of course, be varied and may well be greater than that illustrated in Figs. 10 and 11, Been in relation to the diameter of the channel-parts. The studs may conceivably be distributed in a pattern which will create a "universal slab", in which channel parts may extend in any desired direction and also turn or swing between the studs.

Figs. 12 and 13 illustrate two different embodiments of on-site cast outer coverings, where concrete is cast on sheets or slabs 2 having channel parts 1 disposed therein. The Fig. 12 embodiment has a wave¬ shape transversely to the direction in which "the channel parts extend. The Fig. 13 has a stepped configuration, as shown highly schematically in Fig. 14, formed with the aid of upstanding rim-elements/striker- straight edges 15 in the extension direction of the channel parts.

Figs. 16 and 17 illustrate arrangements using sheets or slabs in which the channel parts are accommodated in preferably essentially ^■ parabolic grooves 14, wherewith the ridges _ ' between the grooves form supports for a floor surface 16 in the form of sheets, slabs 16 or the like and which incorporate locking grooves 3. The channel parts, the hoses, are preferably black, warm and dull, and radiate heat radially, said heat being reflected by preferably white and smooth, parabolic surfaces of the sheet or slab material, the cellular plastic material. In this case, heat transfer is effected by radiation and convection. Ventilating slots are preferably provided on the undersurface of the sheets or slabs.

The method and the manner of operation of the arrangement according to the invention will be understood essentially from the aforegoing.

Because the channel system 1 is disposed on heat-insulating sheets or slabs 2, the mutual effect between the channel system and the substrate or base support, i.e. the ground or the like, will be greatly reduced. The left-hand part of the Fig. 5 illustration shows the transport of heat from the surface of the arrangement, the ice, in full-line arrows and also shows to a limited extent the transportation of heat from the underlying ground through the sheet or slab 2. Shown to the right in Fig. 5 is, among other things, the drainage of water in joints located between respective sheets or slabs 2. The filler material can thus be saturated with moisture through grooves 4. Surplus water drains-off through the joints between respective sheets or slabs. This moisture saturation provides highly efficient heat transfer between the channel parts and the surrounding medium or media.

As illustrated in Figs. 7 and 8, concrete can be cast directly onto the sheets or slabs containing channel-parts, wherewith a pattern of reinforcements 11 can be employed to decrease the average thickness of the concrete layer while maintaining mechanical strength, as illustrated in Fig. 1, and therewith also reducing the amount of thermally active mass. The striker-abutment elements 13 form spacer elements, both when striking-off surplus concrete and when dividing the concrete surface into sections. The striker-abutment elements can be left in the concrete surface, scraped out slightly and replaced with other material, such as concrete.

■ Placing of the channel parts 1 and the durability or permanence of the channel system with regard to its configuration are facilitated by the locking grooves 3. Thus, the channel parts, the hoses, can be readily tramped into the locking grooves during successive placing of said channel parts, therewith fixating the hose or channel partβ against both axial and radial movement.

When the channel parts are pressed into respective locking grooves, said locking grooves preferably having an essentially U-shaped cross- section, the grooves will first widen and then exert a clamping

action on said channel parts, so as to prevent movement of said parts and, inter alia, upward deflection thereof. The frictional forces exerted by the locking grooves, even short locking grooves, are sufficiently large to impede changes in length of the channel parts during the fitting of said parts and even when the rink, pitch or like area, is used in the summer months as, for instance, a football pitch.

Because the channel-parts fit sealingly into the locking grooves, there is formed a water-retaining damming construction which results in moisture saturation of the filler material used.

The channel system is constructed by placing sheets or slabs 2 sequentially in the intended direction of extension of the channel parts, several rows of sheets or slabs being placed adjacent one another. The channel-parts, the hose-parts, are laid in endless loops of reciprocating lengths having an 180'-swing between each pair of sequential lengths extending in the flow direction of the energy- carrying medium, wherewith the channel lengths of one such channel pair need not necessarily lie adjacent to one another, but that the channel parts may be laid so that, upon completion, one or more channel lengths will be located between the two lengths of one such pair. In this case, the radius of curvature in each 180'-swing can be made larger than when the channel length of each channel pair shall lie immediately adjacent one another.

It will be seen from the aforegoing that the inventive method and arrangement afford important advantages of the kind mentioned in the ■introduction.

The invention has been described in the aforegoing with reference to exemplifying embodiments thereof. It will be understood, however, that other embodiments and minor modifications to the illustrated embodiments are conceivable within the scope of the inventive concept.

The sheets or slabs 2 will preferably be made of expanded styrene, propylene or ethylene plastic, although said sheets or slabs may also be cast directly in moulds from foamed polyurethane or polystyrene.

Working from smooth sheets or slabs is also possible principle. The slab material will preferably be relatively hard.

Due, among other things, to the sealing contact achieved between locking groove and channel parts, there is obtained a damming effect which enables the filler material used to be saturated with moisture, resulting in good heat transfer and effective use of the refrigerant concerned. This damming effect can be amplified by providing a raised rim 4' around the outer edges of the sheet or slab, as a complement to the sealing locking grooves etc., as illustrated in Figs. 3 and 4.

It is preferred in many instances to form in the outer edges of the sheets or slabs 2 draining slots 17 which lead to the underlying substrate or foundation, as shown in Figs. 1, 3 and 4. Surplus water in the gravel layer, or rain water, is therewith enabled to drain horizontally through the gravel layer up to the drainage slots, and there pass vertically through the gravel-filled slots down onto a drainage foundation. Naturally, the drainage slots 11 can be formed in several different ways and may have different sizes and different position patterns.

According to one preferred embodiment, a number of the aforedescribed constructional elements, i.e. grooves 4, locking grooves 3, recesses which form buttress-like reinforcements 11 and drainage columns in outer edges, are formed integrally with the sheets or slabs.

Consequently, the invention is not restricted to the aforedescribed and illustrated exemplifying embodiments thereof, since modifications ^• and changes can be made within the scope of the accompanying claims.