SE411457C - USE IN A HEAT CUMULATOR OF A FIBROST BERARM MATERIAL FIXED SORBENT - Google Patents

Description

1714224-s, _ p. 2. heating can be made completely self-sufficient in solar energy with a solar collector area of 40 m2 and a storage unit that can store up to 7,000 kWh seasonally.

Many different forms of storage methods have recently been proposed.

Thus, solar heat storage was already used today by heating e.g. water or a stone bed. The higher the specific heat capacity of the material, the greater the storage capacity of the heat reservoir per volume unit. They are also working on developing heat reservoirs that utilize the so-called latent heat and which is based on the phase transformations of storage media. An example of this is the so-called melt storage where you store the heat by e.g. allow a salt hydrated melt. Such a molten layer has a relatively high storage capacity and contains a relatively large amount of heat per unit volume.

One of the disadvantages of the above-mentioned storage forms is that the heat losses during long-term storage become very large. The storage of heat in water reservoirs is therefore, for example, not suitable for individual homes, but may possibly be suitable for large residential areas so that heat can be stored in very large ponds. In order to further increase the storage capacity and eliminate the disadvantages of heat losses from the heat storage, it has also been proposed to store solar energy or other forms of energy through so-called chemical storage or distillation storage. During distillation storage, one can e.g. use certain chemical substances that can emit (desorb) or binda (sorbera) and gas.

During the desorption (charge), the gas is distilled over to a recipient, which in some cases may be a tank, in which the gas condenses during heat dissipation. During sorption, heat is released.

In order to be able to realize heat storage systems based on distillation storage, it is required that the systems have certain suitable equilibrium vapor pressure data. In general, the vapor pressure at the charging temperature exceeds the corresponding vapor pressure in the recipient at its temperature. lucky. Correspondingly, during sorption the vapor pressure must be less than the recipient vapor pressure. 7714224-8 For this purpose, essentially three different groups of sorbents have been proposed, namely desiccants, such as salt hydrates, ammonia and zeolites.

Salt hydrates are common chemical compounds that have a great ability to bind water, e.g. by sorption of water vapor. The ammonia sorbs ammonia. The zeolites can finally sorb a number of different gases.

In order to be able to obtain a useful system for heat storage according to the distillation method, in addition to the above-mentioned physicochemical D data, other essential conditions must be imposed on the system. Thus, it is not only important that the energy density is high in a storage system, but it must also be possible to achieve a sufficiently fast heat dissipation. The same applies to the regeneration of the heat storage unit, i.e. the evaporation of the gas by heating with e.g. solar heat, y should also be relatively fast.

Another requirement is that the components used are cheap, easily accessible and environmentally friendly.

Sorption resp. the desorption of e.g. salt hydrate or salt ammonia is fast as long as it has a surface effect. However, it has been found that if the sorbate (gas) diffuses slowly into the sorbent grains sintering can easily occur. This leads to a reduction in the sorbent surface and thus leads to small opportunities for acceptable power consumption. These problems are pronounced for hydrates and salt ammonia.

Another important requirement for a distillation system is that sorption resp. the desorption process must be able to be repeated many times without negative changes occurring in the system.

It has been found that especially salt hydrates in powder or granular form during repeated sorption resp. desorption sints and clumps so that the sorption process resp. the desorption process after a few cycles becomes very slow. Another disadvantage has been that the crystallization is inhomogeneous and if the grains are stored in a container a '771lr22lr-8 container a very inhomogeneous and in some places porous sorbent is obtained. In addition to the above-mentioned observations with regard to structural changes, it can also be mentioned that both hydrates and ammonia swell during gas absorption. In this context, it should be noted that the mechanism of the sorption and desorption processes is not yet clear.

It can thus be stated that today there has been extensive theoretical speculation about suitable physico-chemical systems in order to be able to * obtain reversible systems for heat storage by distillation.

Although a number of experiments have been carried out so far, no practical solutions have emerged.

According to the present invention, the above-mentioned problems in distillation storage have surprisingly been solved by impregnating the carrier material in the form of a shaped body, for example a disc or a sheet, with the sorbent in the form of a solution and / or melt or dispersion.

According to a suitable embodiment of the invention, the carrier material is impregnated with the sorbent in the form of a solution and / or melt or dispersion.

Suitably used as sorbent drying agent, such as hydrate and preferably hydrate of the salts CaCl 2, FeCl 2, LiCl, MgCl 2, (NH 4) 2 Zn (SO 4) 2 or NH 4 Al (SO 4) 2 or also ammonia and MnCl2._.

The impregnation can be carried out with a melt or solution of the sorbent.

According to a preferred embodiment of the invention, CaCl 2 is used as sorbent.

The fibrous material suitably consists of highly absorbent high-bulk materials with a certain stiffness, preferably Éärar material such as .v.

P; Cellulose sponges, preferably paper, paperboard, sheets or other moldings made from unbleached or bleached chemical or mechanical pulp or mixtures thereof with or without the addition of synthetic fibers.

Suitably the fibrous material is manufactured by wet forming or dry forming in one or more layers or according to the molded pulp method and treated with suitable binders and other agents so that the carrier material has good absorption capacity during impregnation and good retention ability for the sorbent in melt and liquid phase. The carrier material can, if desired, be made wet-strong and / or wet-rigid by e.g. phenol treatment and before or in some cases after the impregnation is given a suitable form.

A suitable relatively inexpensive carrier material is obtained by using sheets of so-called fluff mass. Other features of the invention are apparent from the features set forth in the appended claims.

According to an embodiment of the invention, sheets of cellulose fiber have been used which sheets have a high absorbency of liquids consisting of melts or solutions. In this way, e.g. the salt hydrate of CaCl2 in molten form or in solution was caused to impregnate a web of cellulosic fiber in the form of a carton. After drying and cooling, a very high content of salt has been fixed in the sheet. If the drying is carried out completely, the salt consists of only CaCl2. The 771lr22lf-8 has surprisingly been found that the salt not only appears to be evenly distributed in the sheet at a high concentration but also that the sheet can be handled while maintaining the position fixation of the salt grains in the sheet. The process of absorption is even more surprising. If e.g. moist air is passed over the flat surfaces of the dried sheet, an immediate absorption of water vapor takes place while releasing heat. During absorption, the sheet gradually becomes moist during heat dissipation {The remarkable thing is that the absorption appears to take place evenly over the surface and that the process also takes place evenly towards the center of the sheet, which is reflected in the fact that the moisture appears to be evenly distributed in the sheet.

As is well known, CaCl2 is a cheap chemical in its technical form and is used e.g. as road salt. A CaCl2 molecule can absorb up to 6 water molecules and the storage capacity naturally increases with the number of absorbed water molecules.

The absorption takes place step by step and so that the first step is CaCl2 + H2 O - CaCl2 'H2 O. the next step is CaCl2' H2 O + H2 O -) CaCl2 ° 2 H2 O The third step gives CaCl the above-mentioned observations as a basis, it can be assumed that in the absorption of t, e.g. salt hydrate powder distributed in a fibrous sheet at least some of the different absorption steps as above will take place simultaneously in different places in the sheet. At the same time, phase transformations probably take place, i.e. the different forms of hydrate will be present during the absorption process in different phases of the sheet. It has now surprisingly been found that the liquid phase of the hydrate is evenly distributed in the sheet, ie during the absorption process the whole sheet appears to be even and gradually moist. This may indicate that when the salt distributed in the sheet during absorption it absorbs so much water that the substance changes to a liquid phase, this liquid spreads in the sheet depending on, for example, the capillary forces.It is also conceivable that the cellulose fiber itself absorbs some salt in the liquid phase.

However, it has not been possible to ascertain what happens during the absorption process in the form of phase changes, nor has it been possible to provide an exhaustive explanation for what happens. It can be stated, however, that as mentioned, the absorption takes place very evenly because the rigid sheet initially dried gradually during the supply of steam softens during strong heat dissipation and that the sheet appears to be gradually and evenly moistened during the absorption process. It has also been found that the process can be interrupted at any time by preventing gas access. Thereafter, after a shorter or longer period of time, the absorption process can be continued by gas supply without any heat transfer to the surroundings during the rest period.

The desorption or charge is accomplished by applying heat to the sheet or body. In cases where a salt hydrate is used, water vapor is thus released and in cases where an ammonia is used, ammonia is released. In an embodiment according to the invention, a heated carrier gas, e.g. dried air to sweep over the surfaces of the sheet or shaped body.

As previously mentioned, one of the problems with distillation storage so far has been that it has not been possible to achieve sufficiently fast power withdrawals. This has i.a. due to the fact that the sorbent grains sinter or form porous structures, which gives a poor thermal conductivity. The problem worsens each time the absorption / desorption cycle is repeated. The sorbent grains themselves also have a relatively poor thermal conductivity. If the distance between the area in the sorbent mass where the heat is developed and the heat-emitting surfaces of the sorbent layer is large, the temperature drop becomes too large and also thereby prevents the possibilities of an acceptable power outlet. The proposals made so far for the design of storage devices to enable an acceptable power take-off by increasing the heat-dissipating surfaces in relation to the thickness of the sorbent layer have not proved to be practically useful. However, it has surprisingly been found that the desorption process in the various embodiments according to the invention is also rapid and that desorption from the mold body or sheet is homogeneous. Despite a large number of repeated cycles, no changes in the desorption process have been observed. By being able to predetermine the dimensions of the shaped body or sheet according to the invention, it is possible to optimize the power outlet in relation to the storage capacity for a certain specific distillation system. Thus, although it has been found that the sorbent grains are evenly distributed in the cavities of the carrier material and that the sorption process is very even, and that to the extent that the salt is present in the liquid phase the liquid is distributed in the sheet probably due to the acting capillary forces. also in this case an increasing thickness of the mold body can lead to a lower power take-off due to an increased temperature drop when heat is transported from the interior of the mold body to its heat-emitting surfaces. One is probably to some extent limited in choosing the thickness of the carrier material.

According to the present invention, storage devices for distillation storage of heat with a high power output combined with a high efficient storage density of the heat storage are also made possible. According to the invention, since the sorbent grains can be distributed in a carrier material in the form of a shaped body with a predetermined dimension, the heat-emitting surfaces of the shaped body can be made accessible for heat removal in a very simple manner. In an embodiment according to the invention, the shaped bodies are constituted by a sheet-shaped or disc-shaped fibrous material. By suitable choice of thickness in relation to the surface of this sheet-shaped material, the size of the heat-emitting surface can be adapted to the thickness of the sheet material.

In addition, the shaped bodies in the form of e.g. sheets have been made manageable and can e.g. caused to be stacked next to each other by suitable devices so that a space is formed between the surfaces. In order to achieve 7714224-8 high total efficient storage capacity, the distance between the surfaces should be as small as possible, however, without the resistance of the gas given off during desorption becoming too great. In cases where a salvage gas e.g. heated air is used, this can with e.g. a fan is caused to pass the spaces between the planar surfaces.

According to the invention, an even distribution of the sorbent grains in a carrier material is thus made possible, as well as a rapid and even sorption and desorption, which processes can be repeated a very large number of times. In addition, a high storage capacity of the sorbent grains in the carrier material is enabled. By suitable dimensioning of the carrier material, an optimal power take-off is made possible at the same time as the efficient storage capacity of the storage container can be kept high.

Some examples of storage capacity that can be achieved in terms of bulk density of the sorbent in the carrier material will be given below. Examples will also be given of embodiments of storage containers that enable rapid power take-off at a very high efficient storage capacity. Examples will also show some suitable methods and devices within the scope of the invention which show that the invention enables heat storage for storage of so-called low temperature heat during about 2000 with a high storage density, high power output and a use of cheap chemicals and carrier materials. Practical solutions of complete inexpensive systems for utilizing solar energy will also be demonstrated.

In the examples below, only experiments with heat storage with hydrate of the salt CaCl2 are reported. This material is very cheap and is available in very large quantities. However, the invention is not limited to this hydrate. Many other hydrates resp. ammonia can be used. It is also conceivable to use other desiccants for practicing the invention.

The technical form of CaCl2 ° 2H2 O occurs as usual road salt most often in the form of flakes. The flakes have a density of about 0.80 g / cm after all water has been removed by drying at at least 90 ° temperature. Another technical quality can be achieved by crushing to obtain powder. The dried powder has a bulk density of about 0.85 g / cm 3.

As will be seen from the examples below, it has been found possible to store surprisingly large amounts of salt in fibrous sheets. It has been possible to e.g. By means of a suitably adapted multi-stage impregnation of sheets of fibrous materials with properties suitable for impregnation, volume weights of the salt of between 0.40 - 0.90 g / cm 3 are achieved.

It should be noted that in these figures the volume weight of the fiber mass has been deducted. It has thus been quite strikingly proven possible to fine-tune and fix the position by e.g. by choosing the right material and impregnation method. a salt. In a fibrous volume with a density of the salt itself which is close to the density of salt powder freely stored in a vessel. The invention has thus obtained an opportunity to fix the position and distribute the sorbent grains evenly in a desired volume which, in terms of its shape and dimension, can be adapted to the system for sorption resp. desorption that is selected and that the sorption resp. the desorption takes place in a very smooth and controllable process. Furthermore, the invention has made it possible for the process of sorption and desorption to be repeated a very large number of times without any changes being detectable.

By a suitable embodiment of the invention where the sorbent e.g. in the form of a salt hydrate is caused to impregnate an absorbent paper or other sheet-like fibrous material, the heat outlet resp. the desorption takes place quickly and evenly by bringing the gas into contact with the flat surfaces of the sheet.

According to the invention, the carrier material can suitably be impregnated with the sorbent in the form of a solution, melt or dispersion. As mentioned, it has proved possible to achieve very high concentrations of sorbent in the fibrous mass. This is achieved i.a. at e.g. impregnation with a hydrate by bringing it into solution or melting at a relatively high temperature. So e.g. For example, various fiber masses have been heat-impregnated with melts of the tetrahydrate of calcium chloride with road salt as raw material. It has been found in most cases that the higher the concentration of the sorbent in relation to the water content, the higher the concentration of the salt in the fibrous mass has been obtained. However, this is provided that the melt or solution at the time of impregnation has a low viscosity. In the mentioned example when impregnating road salt, the viscosity is low even at high concentrations and enables a high content of sorbent.

It has also been found that the impregnation method is important for obtaining a high content of sorbent. For certain fiber masses and sorbents, a multi-stage impregnation can give a very high content. For impregnation, whether in the case of low-stage impregnation or multi-stage impregnation, different impregnation methods known per se can be used. Suitably some form of dip impregnation may be used, i.e. the carrier material in the form of a shaped body e.g. a slice or sheet is dipped in a suitably hot melt or solution of sorbents. In the case of a carrier material in the form of sheets or sheets, the dip impregnation can suitably be combined with the material being brought between one or more rollers, which can help to squeeze the air out of the fibrous mass. It is important that the impregnation takes place as completely as possible and that the entire fiber mass is homogeneously impregnated. However, due to the fact that the fibrous masses most suitable for impregnating the sorbent are usually very bulky, the final step in the impregnation must take place without excessive squeezing of melt or solution. However, a slight scraping or pressing of the solution should take place so that no excess sorbent accompanies the surface, which can lead to problems in the use of the material.

It has also been shown that the properties of the shaped bodies in various respects are of great importance for the result. As mentioned, experiments have been performed with both porous sponge materials and various fibrous materials. It has thereby been shown that fibrous materials have proved to be particularly suitable. This has i.a. According to the invention, it has been found that by a suitable choice of fibrous material which has been imparted to the mold body during molding, certain suitable properties can be obtained with a high content of sorbent and a material suitable for the sorption-desorption process. It has also been found that it is possible to obtain a combination of fiber carrier material / sorbent which not only has suitable technical properties but can also be produced at very low costs.

The reason why certain fibrous materials are suitable is not only that they allow a very high absorption. As mentioned earlier, the sorption and desorption process itself becomes even. In addition, it has been found that a suitably selected fibrous material is suitable because both hydrates and ammonia swell sharply during sorption. An appropriately selected fibrous material has been found to be able to withstand such repeated deformations during repeated sorption / desorption processes.

The choice of fibrous material and its properties as well as the dimensions and properties of the shaped body depend on the type of storage in question.

The invention will be explained in more detail below with reference to the following examples and a number of exemplary embodiments shown in the accompanying drawings, in which Fig. 1 shows a section through two sheets prepared according to the invention, spaced apart, Figs. 2 and 3 'show similar section as Fig. 1, where spacers are arranged between the sheets, Fig. 4 shows a view of a heat accumulator produced according to the invention and Fig. 5 shows a shaped body produced according to the invention with internal cavities.

Fig. 1 shows a section through two such disc-shaped moldings 1 arranged at some distance from each other, whereby maximum gas sorption and gas desorption are obtained over the flat surfaces of the discs. In cases where the shaped bodies are disc-shaped, it is suitable that in order to form a package of discs with a suitable distance between the discs they are supported and fixed in position with suitable devices.

In Figs. 2 and 3 it is shown that this distance between two discs 1 can be achieved by using different spacers.

Fig. 2 shows on average how the position fixation between two discs 1 has been achieved with a folded liner 3, which due to the folding only touches and supports the discs at certain points. In this way, a suitable number of discs 1 can be arranged on each other and form a package.

The sorbents present in the discs, for example salt hydrates, can soften during sorption, but by using the liner 3 the discs are supported and kept at a distance from each other. However, because the corrugated liner 3 has relatively pointed peaks 2, most of the surface of the disc is exposed.

The spacer 3 can consist of many different materials. These should be affordable and not soft e.g. by wetting due to absorption of hydrate solution. Suitable materials for this are, for example, cured phenolic resin impregnated kraft paper, rigid plastic foils, many other embodiments and other materials are of course conceivable.

Fig. 3 shows examples of how the desired space between two plates 1 has been achieved by having ridges 4 in the carrier material. In such a case, the carrier material itself must be treated before or after the impregnation so that at least the ridges 4 are rigid and resist moisture. Such stiffening can take place, for example, by treatment with a thermosetting plastic, for example phenol.

Fig. 4 shows a further embodiment for joining several disc-shaped moldings into a cassette-like device.

The shaped bodies 1 containing the sorbent are placed in pairs by means of spacers 3, which allow gas passage between the discs. The discs are enclosed in a cassette-like housing 7. Correspondingly, another pair of discs 1a is placed in a cassette 8 under the cassette 7714224-8 14 7, so that a gap 9 is formed between the cassettes. Through the gap 9, suitable transport medium can be supplied resp. diverted to the outer planar surfaces of the discs.

In Fig. 5, the shaped bodies 1 consist of parallelepipeds which are positioned at a distance from each other and have a substantially square cross-section. I resp. mold body, cavities 6 can be present for supply resp. removal of heat.

As mentioned, the choice of fiber material and its properties are of great importance for the result. In the case of sheet-shaped or disc-shaped moldings, these are suitably produced in a manner known per se by wet molding on a paper or board machine or by so-called dry forming whereby the dry fibrous material is blown on a pick-up device. The fiber bonding in dry forming can take place by so-called hydrogen bonding i.e. by the presence of water or with synthetic binders. However, the production of shaped bodies can also take place in other ways, e.g. through a so-called molded-pulp-process.

It has been shown that a decisive factor for both a high impregnation content and an even sorption / desorption is the properties of both the fibrous material and the shaped body before impregnation.

Thus, it has been found that a very high bulk i.e. a low volume weight gives both a high sorbent content and a fast impregnation. It has also been shown that in some cases it is advantageous to have relatively long fibers of e.g. cellulose or bunull. An excessively high content of short fibers sometimes tends to clog some cavities and impairs impregnation. 7711æ224-8 _. ._ ___ At e.g. use of salt hydrate sorbents, it is also important that the carrier material has an ability to hold the hydrate in the liquid phase after rehydration so that the liquid does not flow out of the mold body.

This is achieved i.a. in that the fibrous material and the fibrous mass have a certain stiffness, i.e. can retain their bulky structure despite repeated sorption / desorption cycles. In some cases an addition of synthetic fibers is suitable.

The most suitable cellulose material for technical reasons is bleached chemical cellulose. By i.a. For cost reasons, one would prefer unbleached sulphate pulp, but some problems may arise due to the hydrophobic properties of the material, which can, however, be remedied with surfactants.

Thermomechanical mass with relatively high freeness is also suitable i.a. because it is cheap and the fibers are stiff. with the wet method, a bulky carrier material with suitable properties in the form of e.g. boards or endless webs of cardboard. By means of suitable measures, a bulk density of about 0.4 g / cm 3 of the finished carrier material can be obtained. In some cases it can come down to 0.2 g / cm3, which corresponds to a bulk of 5 m3 / g.

The s.k. the dry method usually enables the production of very bulky materials. A bulk of 5 to 6 can be achieved.

It is also possible to use multilayer material, where, for example, the surface layers consist of a different type of fiber than in the middle of the material.

In order to obtain thick carrier materials e.g. in the form of sheets or discs, several sheets can be joined together with e.g. lamination. This can be done by, for example, extruding a thermoplastic film. The laminates can be made to obtain a certain increased stiffness by suitable choice of laminating agent. If the lamination is done with a whole film, it should only be done with two sheets so that sorption can take place inwards from each surface. If multilayer laminate is desired, lamination can be done with mesh or by other means for the sorbent and sorbate permeable laminating agent. 1714224-a 16 In some cases it is suitable to coat or laminate one outer surface of the carrier material with a film of e.g. plastic. Such treatment, in particular in the case of accumulators arranged horizontally, can prevent the carrier material from being able to hold any sorbate solution formed in the event that it does not drip onto the underlying accumulator parts. Admittedly, sorption cannot take place from the surface thus treated, but it has been found that if the sorbent solution is blocked with e.g. a plastic film solution is again absorbed into the carrier material upon desorption. In principle, the carrier material itself must be self-supporting before impregnation.

Through the choice of material and manufacturing process, one can thus produce a material e.g. in disc form which is suitable both for impregnation with a high content of sorbent and to give a final product carrier / sorbent with suitable sorption / desorption properties.

It has been found that the carrier material swells during the impregnation.

The same applies to the finished shaped body of sorbent / carrier during sorption. It is therefore necessary that the fibrous mass can withstand swelling during repeated sorption / desorption processes¿ One might think that the discs or sheets must be relatively thin to enable a sufficiently fast sorption i.e. an acceptable power outlet.

However, it has surprisingly been shown that even thick discs or sheets can leave a very large power output.

Fig. 1 illustrates how the absorption takes place even in a relatively thick sheet material. The slices 1 and 2 are shown in Fig. 1 in cross section and the shadow marking shows a soft layer of hydrate which during sorption increases in thickness and from both surfaces of the sheet gradually penetrates inwards. Experiments have shown that the sorption takes place surprisingly evenly inwards and also enables high power outputs, until the central layer of sorbent has sorbed the gas.

Thanks to this surprising effect, one can thus further increase efficient storage capacities by choosing thick sheet or disc materials; 1? The table below shows examples of some different salinities after impregnation of different support materials with hydrates of calcium chloride that have been achieved. The impregnation has taken place with equal concentration of the salt hydrate and at 95 ° temperature. the values have been calculated with regard to the swelling after impregnation and drying and refer only to the volume weight of the dry salt, i.e. the volume weight of the fibrous mass has been deducted. As a comparison for the values, an experiment with impregnation of a sponge material has been included. 7714224-8 1714224-s Jia '' Carrier material The impregnated and dried material no. type density thickness dry salt g / cm3 mm density thickness number of impreg- g / cm3 mm nutrients 1 aenuiosas fungus 50.09 4.5 0.12 5.0 1 2 air filter paper (lightly phenol impregnated) 0.30 0.50 0, 0.53 l 3 impregnation paper for laminate sheets (unbleached force) 0.50 0, l6 0.30 0.20 l 0 impregnation paper for the cover layer for laminate paper (bleached cellulose) slightly _ wet strong 0.55 0.00 0.05 0, 05 l '"' 0,55 0,00 0,57 0,52 2 6 -" - 0,55 0,00 0,75 0,57 3 7 high-absorbent high-bulk cardboard (wet-bleached cellulose) 0,05 l, 96 0.65 2.80 l 8 wet-shaped bulky disc of bleached cellulose 0.00 9.0 0.55 10.2 1 9 dry-shaped bulky disc thermomechanical mass 0.29 3.0 0.75 0, 1 1 7714224- 8 19 The table shows that even with 1-step impregnation, a very high bulk density of the dry salt can be achieved by using a suitable carrier material (nos. 7, 8 and 9), mainly with high bulk. High volume weight of the dry salt can also be achieved by multi-stage impregnation (Nos. 5 and 6). However, as mentioned, the ability of the fibrous material to be able to retain the liquid phase after sorption, insofar as such is present, is also important. In this respect, the properties of the fibrous material are of great importance. It has e.g. It was found that the impregnated material corresponding to sample 3 had a poorer ability to retain the liquid phase after sorption than e.g. the material according to samples 7 and 9. The investigation has shown that fiber length, fiber fineness and fiber stiffness are of great importance. In some cases, it has also been shown that a high salinity gives a poorer ability to retain the liquid phase. The properties of the fibrous material during wetting seem to be important for the sorption / desorption process. Thus, a fibrous material with hydrophilic properties seems to be preferred. The properties seem to be affected by the appropriate choice of pH or in the case of thermomechanical pulp by the addition of bleached pulp.

The following examples carried out in a test plant are intended to show examples of which storage densities, energy and power outlets can be obtained with a device according to the invention.

Example 1 A highly absorbent carrier material in the form of a bulky carton with good holding capacity for the liquid phase of the hydrate was impregnated with hydrate of road salt. The carrier material and the shaped body thus impregnated were of the same type as No. 7 in the previously shown table. Several plates were stacked on top of each other into a lamella package. The tiles each had a thickness of 3 mm in the dry state. The bulk density of the dry salt was 0.65 g / cm 3. The space between the plates was 1 mm.

The plates were 7.9 cm wide and 6.9 cm long. The total volume (gross volume) of the package was 0.12 dm3. The package was placed in an air duct with a cross-sectional area of 2.1 cmz and a width of 7.9 cm. A fan blew moist outside air through the package before the sorbent tank (package) and after the tank, the moisture content and temperature could be read. The air flow in the duct could also be measured. The experiment lasted for 40 minutes. Through temperature, humidity and air volume measurements, temperature rises of the dry thermometer could be registered at the same time as power outputs and energy outputs could be calculated. The experiment was stopped after about half of the stored energy had been extracted.

Results are shown in the table below.

Power output (heat content change per unit time in outgoing air and water vapor) time min. after start 4 30.3 watts 0 23.4 watts I 18.9 watts l6.0 watts average value 20.7 watts Energy outlet: 10.4 wh Air speed through the slats 6 m / sec.

Based on the above test results, energy consumption, power output, and energy density could be calculated with the following results: Energy output (only 70% of possible) 295 kwh / ton dry salt 110 kwh / m3 gross volume Power output max 254 kw / m3 package volume min 133 kw / m3 paketvoiym Power outlet max 0.56 kw / m2 lamella surface min 0.30 kw / m2 lamella surface It seems that the power outlet decreased during the experiment. At the same time, it was observed that the outgoing moisture content increased. It is interpreted as meaning that vapor absorption decreased. More constant conditions have been possible by arranging a significantly longer absorption distance. Then the rising excess of moisture in the first part had been absorbed in the following parts with a concomitant rise in temperature and thus the power output could be kept relatively constant.

The experiment also shows very high power output per m2 of board area despite relatively modest amounts of moisture in the air. In the above experiment, the salinity was 0.38 g dry salt per cm 3 gross volume of storage tank.

As previously mentioned, in most cases it is desirable to achieve a very high salinity in order to thus obtain a large storage capacity per unit volume. The following are examples of impregnation and various storage capacities obtained by impregnation with calcium chloride hydrate.

Example 2 A highly absorbent board with a very high bulk was chosen as the carrier material. The thickness of the carton was 2.0 mm and the density 0.24 g / cm 3, which corresponds to a bulk 4.25 cm 3 / g. The fibrous material was bleached cellulose. The sorbent salt was road salt, i.e. CaCl2 ° 2H2O.

First, an experiment was performed which was intended to produce the highest possible bulk density of salt. A melt of calcium chloride hydrate was prepared where the proportions were 75% by weight salt and 25% by weight water, i.e. the melt contained mainly CaCl2, 2H2O. Impregnation was by dipping the sheet at a melting temperature of 110 ° C. Another experiment was carried out with a melt having the proportions of 52% by weight of CaCl2 and 48% by weight of water. The composition of the melt / solution was obviously a mixture of CaCl 2 .4 H 2 O and CaCl 2 .6 H 2 O. After the impregnations, the sheets were dried and the bulk density of dry salt was determined. At the same time, the thickness changes were registered during impregnation and drying.

The results of the first experiment are shown in the table below. gßärar material The impregnated material ____________________ thickness density thickness density density mm g / cm3 wet dry dry salt fibrous mass mm mm 2.00 0.24 3.55 3.20 0.70 0.15 When impregnating with the melt with the higher water content according to the second experiment a dry salt density of 0.47 g / cm 3 was obtained.

As can be seen from the table above, the material swells sharply during the impregnation, which leads to a reduction in the density of the fibrous mass. Remarkably, the total density of dry salt and pulp in the impregnated and dried material is 0.85 g / cm 3 which largely coincides with the density of the free powder. It was further apparent from the experiments that the density of the dry salt becomes lower at a higher heat content in the hydrate melt. It was also found that the swelling during the impregnation was considerably less, which in this case meant a higher density of the fibrous mass and a lower density of the dry salt. When impregnated with the same water content in the hydrate melt, the swelling became greater with a longer impregnation time.

You can thus also influence the density by means of the impregnation time.

In this context, it should be pointed out that the highest possible content of dry salt is not always desirable. In some cases, an extremely high content of salt and a correspondingly low content of fibers in e.g. large power outlets lead to sorption difficulties. An optimization of the density of the dry salt and the fibrous mass i.a. with regard to the desired power and energy outputs is therefore necessary.

A calculation of which salinities per gross volume unit can be achieved using plates assembled into lamella packages in the same way as described in Example 1 shows that the plates according to the first experiment give a salinity of 0.56 g / cm 3 gross volume and the plates according to second experiment 0.47 g / cm3. In the case of a sorption process with the utilization of energy extraction of dry CaCl2 up to and including the formation of CaCl2 ~ 4H2O becomes the maximum amount of energy extractable, i.e. maximum storage capacity 280 kwh / m3 gross volume storage tank in the first case, which may be considered very high.

By using plates with a high salinity and using thicker plates, the salinity of, for example, CaCl2 of up to 0.55 - 0.65 g / cm3 gross volume can be achieved. Since the salt in this case has a free powder density of about 0.85 g / cm 3, it will be appreciated that a very high storage capacity can be achieved. In Example 1 it is% f %% = 45% of the powder and in Example 2 gfšg = 66%. It should thus be possible to achieve a maximum of ¥ 70% or slightly more by suitable dimensioning of the lamella system together with a suitable choice of fiber material and impregnation method.

In conclusion, it should be emphasized that although the present examples and principal systems have mainly been exemplified as systems for residential heating and with desorption by means of solar panels, the invention is not limited to these areas of use.

Desorption can take place centrally through e.g. recovery of excess heat or generated by central solar panels and the packages thus charged with sorbent are distributed in an appropriate manner.

Furthermore, the invention can be used for heat storage in many other areas than for heating homes.

In the examples given, the sorbent has been road salt. However, as mentioned, the invention can be practiced using other desiccants, such as hydrates, ammonia and zeolites.

Claims (20)

.-..-. ~ _u - uøcu-vw-nn-uvw ~ u | un ~ n --- ~ - ~ M-w-euuu-nlwv- fi * 771142210-8 2ü P a t e n t k r_a v Use in a heat accumulator for controlled storage, storage and release of heat by means of desiccants, such as salt hydrates; ammonia or zeolite based distillate storage system of a sorbent fixed in a fibrous support material, which is prepared by impregnating the support material in the form of a shaped body, for example a disk or a sheet, with the sorbent in the form of a solution and / or melting or dispersion. Use according to claim 1, characterized in that the carrier material is impregnated with the sorbent in the form of a solution and / or melt or dispersion. A Use according to claims 1 and 2, characterized in that the sorbent consists of desiccant, such as hydrate. Use according to one or more of Claims 1 to 3, characterized in that the sorbents consist of hydrates of the salts C612, FeCl2, LiCl, MgCl2, (NH2) 2 Zn (SO2) 2 or »nH2A1 (so¿) 2. Use according to claim 1, characterized in that the sorbents consist of ammonates of the salts Ca Brz, Fe C12, Mn C12. 6. -6. Use according to one or more of Claims 1 to 5, characterized in that the impregnation is carried out with a melt of the sorbent. Use according to one or more of Claims 1 to 5, characterized in that the impregnation is carried out with a sorbent solution. Use according to one or more of Claims 1 to 5, characterized in that the sorbent solution and / or the melt contains at least 50% by weight of water bound to 8%. , g 'd2¿g 7714224-s Use according to one or more of the preceding claims, characterized in that the sorbent consists of CaCl 2 » Use according to one or more of the preceding claims, characterized in that the impregnation is carried out at elevated temperature. 11. ll. Use according to one or more of claims 1 to 10, characterized in that the impregnation is carried out in several steps; Use according to claims 1 - 11, characterized in that the carrier material in the form of a mold body, for example a disc or a sheet, is dipped in a hot melt or solution of the sorbent, Use according to claim 12, characterized in that the dip impregnation is combined with a removal of air present in the material, for example by treating the material between one or more rollers. IN Use according to claim 13, characterized in that the fibrous material before the impregnation is formed into sheet-shaped or disc-shaped moldings by wet molding, dry molding or a so-called molded-pulp ~ process. V Use according to one or more of Claims 14, 14, characterized in that the carrier material used consists of highly absorbent high-bulk materials. Use according to claim 15, characterized in that the carrier material consists of paper, cardboard, sheets or other shaped bodies made of unbleached or bleached chemical or mechanical pulp or mixtures thereof. Use according to claims 1 - 16, characterized in that the fibrous material contains a high proportion of long fibers, preferably cellulose fibers. 771422Å-A8 23 Use according to claims 1 - 17, k 8 n n e t e c k n a d in that the carrier material contains synthetic fibers. Use according to claims 1 - 18, characterized in that an improved impregnation of the mold body with a hard plastic, for example phenol, is obtained by obtaining an improved wet strength, formability and dimensional rigidity. Use according to claims 1 - 19. characterized in that a web of Bulkly fibrous material is impregnated with a sorbent 1 melt or solution and then dried: and cooled. Use according to one or more of claims 1 to 20, characterized in that the carrier material exhibits good retentilation properties for the eorbent. Aurönoa PuaL1xA11oNER: Sweden 391 708 (c0ks 39/08) Germany 2,312 0ß0 (8010 39/16)