SE507477C2 - Process for producing an element for the exchange of total thermal energy - Google Patents

Abstract

The method involves adhesion of inorganic adsorber particles (5) with an average micro-pore dia. of 4 - 6A on a surface of a plate (14) by means of an adhesive layer (2). The plate is then corrugated, with a wave height of 1 - 2.6 mm, and a wave length of 2.5-5mm. Alternating lamination is then effected using a flat plate and one corrugated to form a component with several narrow channels. The inorganic adsorber is a hydrophilic zeolite, and its particles (5) are so adhered that they are partly implanted in the adhesive layer (2), with another part projecting outwards. They are blown on to the adhesive layer which by prior heating is semi-dry, so that they provisionally adhere. The layer and particles are then heated to a temp. of 100 - 250 deg. C., so that the adhesive hardens, and this during a short period so that the micropores of the adsorber are not blocked by the adhesive. USE - To produce a component for a total heat energy exchanger.

Description

507 477 2 problems during manufacture and use. Especially during corrugation, the film can be torn so that corrugation becomes impossible.

Also important is the size of the cross-sectional area of the small channels in a honeycomb structure formed by corrugating and laminating a film. When the small ducts have an excessively large cross-sectional area, the total surface area of the film becomes small, which reduces the contact area for passing air and reduces the efficiency of the total heat energy exchange. When, on the other hand, the small ones. the ducts have too small a cross-sectional area, increase the resistance to air or other gas passing through the element (ie the pressure drop increases), which requires a higher driving force and makes economical operation impossible.

According to the invention, the above problems are solved in the following manner. Particles of hydrophilic zeolite or other organic adsorbent containing micropores with an average diameter of 4-6 Å, ie adsorbents that adsorb molecules of water vapor but hardly adsorb molecules of odorants, are adhered to the surface of a metal film , plastics or the like, the thickness of which is in the range of 0.02-0.15 mm. The film is then corrugated to a wavelength of 2.5-5.0 mm and a wavelength of 1.0-2.6 mm. Flat films and corrugated films are laminated alternately to form an element with many small channels.

The invention is described in more detail below with reference to the accompanying drawing, in which Fig. 1 schematically illustrates the first embodiment of the method according to the invention; Fig. 2 is a perspective view of an element for exchanging total heat energy produced according to the present invention; Fig. 3 is a section illustrating the use of an element for exchanging total heat energy; Fig. 4 is a perspective view of a portion of a corrugated film; Fig. 5 is a graph of the degree of transfer (%) and amount (ppm) of benzene and toluene transferred as a function of the average micropore diameter of an adsorbent on the surface of a film; Fig. 6 is a diagram showing how the efficiency of the total heat yield n (%) and the static pressure drop AP (mm H 2 O) change when changing the wavelength and wave height of a corrugated film; Fig. 7 is a diagram showing how the heat exchange efficiency changes when changing the amount of hydrophilic zeolite on the surface of a film; and Fig. 8 is a graph showing how the heat exchange efficiency changes when changing the average micropore diameter of zeolites.

Preferred embodiments of the invention are described in detail below.

Example 1 Fig. 1 shows a device used in the method according to the invention. The drawing shows a vessel 1 for binder 2, a drying device 3 and a vessel 4 for adsorbent 5.

Particles of the adsorbent 5 are transported by an air stream via nozzles 7, 8 to the surface of a film in a chamber 9, using a fan 6. The particles of the adsorbent are supplied via a hopper 10. The drawing further shows a drying device 11, a return line 12 which returns particles of the adsorbent 5 from the chamber 9, and a drying device 13.

On both sides of a 30 μm thick aluminum film 14, a polyvinyl acetate type binder 2 is applied in a 10-30 μm thick layer by adjusting the gap between two rollers 15.

After passing through the dryer 23, the adhesive layer is semi-dry (viscous but not solidified), which means that zeolite particles cannot be completely buried in this layer. The film with adhesive layer is passed into the chamber 9, and on both sides of the film, particles of hydrophilic synthetic zeolite 5 (Zeolium A-4 from Toyo Soda Co; micropore diameter 4 Å) with a diameter of less than 100 μm are applied by means of an air stream. A total of about 12 g of synthetic zeolite per m2 is applied to both sides of the film. The film is then heated immediately in the dryer 11, which is preferably an infrared dryer, at a temperature of 100-250 ° C for a short time, for example a maximum of 10 seconds, so that the binder is completely dried and caused to solidify.

At the same time, gases adsorbed in the micropores of the zeolite particles are released, forming cohesive pores extending to the surface of the binder layer, so that the adsorption capacity of the zeolite particles is not inhibited. The film is then heated at a high temperature (150-220 ° C) in the drying device 13 so that the adhesive layer solidifies further and stabilizes. By suitable methods, not shown, such as blowing with air or washing with water, zeolite particles which have not adhered properly are then continuously removed to obtain an aluminum film 16 with adhesive particles of synthetic zeolite. The film 16 is fed at a speed of 0.1-0.5 m / s.

The aluminum film 16 with adhesive synthetic zeolite is then corrugated (see Figures 2 and 4). A flat film 16 and a corrugated film 17 are adhered to each other and then wound around a hub 18 to a cylindrical body of the desired size containing many small channels 19 extending between the two end faces. Several depressions are made in the radial direction in both end surfaces of the cylinder, and reinforcing spokes 20, 20 are applied in these depressions. An outer steel plate 21 is wound around the cylindrical surface. One end of each spoke 20 is attached to one end surface of the hub 18. , and the other end is fastened to the outer steel plate 21, for example by means of bolts.

Edge plates 22, 22 are attached along both edges of the outer steel plate 21, and between the edge plates 22, 22 are interconnecting plates 23, 23. In this way an element for exchanging total heat energy is obtained.

Example 2 On both sides of a 30 μm thick aluminum film is applied a 10-30 μm thick layer of a polyvinyl acetate type binder containing up to 30% particles of hydrophilic synthetic zeolite (Molecular Sieve 4A from Union Showa Co. Ltd .; micropore diameter). 4 Å) with a diameter of less than 100 μm as adsorbent and not more than 10% of a blowing agent, which decomposes on heating to produce a gas, preferably carbon dioxide, such as sodium bicarbonate or ammonium carbonate. When the binder is semi-dry but not completely dry, the film is heated at 100-250 ° C to decompose the blowing agent. In the same manner as in Example 1, the aluminum film is then corrugated, and flat and corrugated films are laminated to each other, whereupon an element is produced in the same manner as in Example 1.

Other methods can also be used. For example, a mixture of binder and blowing agent may be applied to the film, after which particles of adsorbent are blown onto the film as in Example 1 and the adsorbent is made to adhere. at the film by heating. 507.47? As materials in the film, in addition to aluminum, other metals or alloys can be selected, for example aluminum alloys, stainless steel, copper and brass; plastics, such as polyvinyl chloride, polypropylene and polyesters; as well as corrugated paper. A paper should consist mainly of inorganic fibers so that it does not catch fire on contact with high temperature air, for example paper of ceramic fibers consisting of 50-90% ceramic fibers with a fiber diameter of about 5 μm and a fiber length of 1-5 mm, 30-5% pulp and 10-20% reinforcing fillers. As the binder, one can use polyvinyl acetate, epoxy resin, silicone resin, acrylic resin and the like. As an adsorbent, it is necessary to choose a material which adsorbs water molecules but hardly odors, especially not those odors which are generated in toilets and kitchens or vapors of organic solvents. Water molecules have a diameter of 2.8-3.2 Å, and molecules of benzene and toluene have a diameter of about 6.7 Å. Both odorants and organic solvents have larger molecular diameters than water. For selective adsorption of water vapor in the presence of odors or vapors of organic solvents, therefore, hydrophilic inorganic adsorbents are used, eg zeolites, whose average micropore diameter is in the range 4-6 Å. Heating is required for desorption of water molecules adsorbed on adsorbents with a micropore diameter of Z3 Ã, eg zeolite of type 3 A, since this micropore diameter is almost equal to the diameter of the water molecules. When operating an element for the exchange of total heat energy containing adsorbent with a micropore diameter of 3 Å, the efficiency of the exchange of latent heat energy is therefore very low. For this reason, according to the invention, adsorbents with a micropore diameter of at least 4 Å are used.

Fig. 23 shows a cylindrical element 26 manufactured in the manner described in the examples above. This element can be rotated about an axis 24 in a housing 25. Through the ducts 27, 28, 29 and 30 the end surfaces of the element 26 are divided into a zone for outside air OA, a zone for supply air SA, a zone for return air RA and a zone for exhaust air EA. Element 26 is rotated at a speed of about 10-15 revolutions 'per' minute, and outside air OA and return air. RA 507 477 6 is led to the element. Through the walls of the small ducts 19 in the element 26, total heat energy is exchanged between the two air streams, and in this case supply air SA and exhaust air EA are obtained.

Fig. 5 shows the degree of conversion (%) and the amount (ppm) of benzene and toluene transferred as a function of the micropore diameter of the adsorbent. Transmission from return air to supply air has been determined in the following way. An element prepared in the same manner as in Example 1 is used by adhering adsorbent to both sides of a 30 μm thick aluminum film in an amount of a total of 15 g / m 2. The corrugated film has a wavelength β of 3.4 mm and a wavelength h of 1.8 mm (see Fig. 4). The element has a thickness t of 200 mm (see Fig. 3). Zeolum A-4 (micropord diameter 4 Å) and Zeolum F-9 (micropord diameter 10 Å) (comparative examples) are used as adsorbents, both of which are hydrophilic synthetic zeolites. As the return air, air containing 300 ppm of benzene or toluene (both having a molecular diameter of 6.7 Å) is used, and this air has a temperature of 25 ° C and an absolute humidity of 10 g / kg. When hydrophilic synthetic zeolite having a micropore diameter of 10 Å or silica gel is used, benzene and toluene are adsorbed in the return air by the element and transferred to the supply air, and the concentration may possibly exceed the level at which a human begins to perceive the odor (1, 5 ppm for benzene and 0.48 ppm for toluene). See "Pollution and Poison / Dangerous Objects (Organic Matter Part)" by Hiroshi Horigudri, Sankyo Publishing Co., Ltd, June 25, 1971, page 458. However, when using a hydrophilic synthetic zeolite having a micropore diameter of 4 Å, there is no risk of that the concentration of odoriferous substances transferred to the supply air must reach the levels that can be perceived by humans.

When the return air consists of air containing various odorous gases generated: in kitchens and toilets, the transfer of these gases to the supply air can usually be prevented by using an element produced according to the invention. Since the outer surface of zeolites is only about 1% of the total surface including the surface of the micropores, the amount of large particles (which cannot penetrate into the ndcropores) adsorbed on the outer surface is as small as 0.2-1.0% by weight. 507 477 7 Fig. 6 (a) shows the efficiency of the total heat exchange n (%) and Fig. 6 (b) the static pressure drop1 20 P (mm H 2 O), when the exchange of total heat energy is carried out with an element prepared according to example 1. This causes Zeolum A-4 to adhere to both sides of a 30 μm thick aluminum film in a total amount of 15 g / m 2. The coated film is corrugated 'to different wavelengths P and wavelengths h as shown below.

Wavelength, mm Wave height, mm A (cf. ex) 2.0 1.0 B 2.5 1.3 C 3.4 1.8 D 4.2 2.2 E 5.0 2.6 F (cf. ex) 6.0 3.6 The thickness t of the element is 200 mm. The external air OA has a temperature of 35 ° C and an absolute humidity of 15 g / kg, and the return air RA has a temperature of 25 ° C and an absolute humidity of 10 g / kg.

In Fig. 6 the velocity of the outside air and the return air (m / s) at the inlet to the element 26 is indicated along the abscissa. The results in Fig. 6 show that when the wavelength of the corrugated film is less than 2.5 mm (e.g. 2.0 mm) and the wave height is less than 1.0 mm (eg 0.8 mm), then the static pressure drop increases sharply, which increases the required driving force TQH: where 'Air density, Q is the air flow and H is the pressure drop. No energy saving is possible in this case. On the other hand, if the wavelength is greater than 5.0 mm and the wave height is greater than 2.6 mm, the efficiency of the total heat exchange will be low, and the energy savings will be lower than the required drive energy.

Fig. 7 shows the efficiency of the exchange of latent heat energy nx (%) and the efficiency of the exchange of sensible heat energy ns (%), when the exchange of total heat energy is carried out with an element prepared in the following manner. Zeolum A-4 is adhered to both sides of a 30 μm thick aluminum film in a total amount of 4 g, 6 g, 15 g or 20 g per m 2. The coated film is corrugated to a wavelength β of 3.4 mm and a wavelength h of 50 mm. The thickness t of the element, i.e. the length of the small channels, is 200 mm. The outside air has a temperature of 35 ° C and an absolute humidity of 15 g / kg, and the return air has a temperature of 27 ° C and an absolute humidity of 10 g / kg. The air velocity at the inlet to the element is 1-4 m / s. The efficiency of the exchange of sensible heat energy is constant regardless of the amount of adsorbent on the film.

In Fig. 7, the velocity (m / s) of the outside air and the return air at the inlet are indicated along the abscissa. From Fig. 7 it can be seen that when the amount of adsorbent on both sides of the film is at least 6 g (m 2, the efficiency of the yield of latent heat energy is relatively high, for example as high as 70% at an air velocity of 2 m / s when the amount Zeolum A-4 is a total of 6 g / m2, so the efficiency of the total heat exchange is high.

The efficiency of the total heat exchange nI can be calculated according to the following formula. nI = [uOA - iSA) / (i0A - iRAH x 100% where i denotes enthalpy of OA, SA or RA.

When the total amount of Zeolum A-4 is less than 6 g / m2, eg 4 g / m2, the efficiency of the yield of latent heat energy is low, eg 55% at an air speed of 2 m / s. The efficiency of the total heat exchange is therefore low. If, on the other hand, the total amount of Zeolum A-4 is increased to more than 20 g / m2, there will be no further increase in the efficiency of the exchange of latent heat energy, but the only effect will be an increase in costs. It is possible that particles of the adsorbent may be removed with the supply air or exhaust air and that the transfer of odorants may increase when adsorbents other than zeolites are used.

Elements for the exchange of total heat energy are prepared by adhering zeolites with a micropore diameter of 3 Å, 4 Å, 6 Å or 9 Å to both sides of a 30 μm thick aluminum film in a total amount of 15 g / m 2. Otherwise, the production and operating conditions are the same as in the experiments reported in Fig. 7. The results obtained are shown in Fig. 8, partly the efficiency value nx and partly the efficiency value ns. The efficiency of the exchange of sensible heat energy is constant regardless of the micropore size of the adhesive zeolite. When using a zeolite with a microprost size of 3 Ã, the efficiency of the yield of latent heat energy is low, which means that the efficiency of the total heat exchange is also low (see the formula above). Such an element does not save energy, especially not when treating very humid air.

All the above results have been obtained using an aluminum film. Almost the same result is obtained if a film of another metal or a plastic film is used instead.

As described above, according to the invention, an element for exchanging total heat energy is prepared by adhering particles of hydrophilic zeolite or other inorganic adsorbent having an average micropore diameter of 4-6 Å to the surface of a film, after which 'flat films and. corrugated films with a wavelength of 2.5-5.0 mm and a wavelength of 1.0-2.6 mm are laminated to each other and wound into an element with many small channels extending from end surface to end surface. Such an element can prevent odorants from being transferred from the return air to the supply air, and it also has a sufficient duct opening ratio. Because the inorganic adsorbents used in the element have an average micropore diameter of 4-6 Å, water molecules can be easily adsorbed and desorbed. The element also provides an economically satisfactory efficiency of the total heat exchange, it provides low operating costs because the driving force is low due to low pressure drop, and it is cheap to manufacture.

Claims (7)

507 477 10 P a t e n t k r a v A process for producing an element for exchanging total heat energy; characterized in that particles of inorganic adsorbent having an average micropore diameter of 4-6 Å are caused to adhere to the surface of a film by means of an adhesive layer, that the film is corrugated to a wavelength of 2.5-5.0 mm and a wave height of 1.0-2.6 mm, and that flat and corrugated coated films are laminated to each other and formed into an element with many small channels. Process according to Claim 1, characterized in that the inorganic adsorbent is a hydrophilic zeolite. 3. A method according to claim 1 or 2, characterized in that the particles of inorganic adsorbent are made to adhere in such a way that they are partly buried in and partly exposed on the outside of the binder layer. Process according to Claim 3, characterized in that the particles of inorganic adsorbent are blown onto an incompletely dried binder layer so that they adhere to it temporarily, after which the particles and the binder layer are immediately heated at a temperature of 100-250 ° C for a short time so that the binder solidifies and binds the particles without clogging the micropores in the particles. 5. A process for producing an element for exchanging total heat energy, characterized in that a binder containing particles of inorganic adsorbent with an average micropore diameter of 4-6 Å and a blowing agent is applied in a layer on the surface of a film, that the coated film is heated at a temperature of 100-250 ° C before the adhesive has solidified so that many continuous pores are formed in the adhesive layer of the blowing agent, whereby the micropores in the particles are not clogged, so that the film is corrugated to a wavelength of 2.5- 5.0 mm and a wave height of 1.0-2.6 mm, and that flat and corrugated coated films are laminated to each other and formed into an element with many small channels. 6. A method according to any one of claims 1-5, characterized in that the film is a metal film, a plastic film or a paper of inorganic fibers. 507 '477 11 A method according to any one of claims 1-6, characterized in that the amount of inorganic adsorbent which is brought to adhere to the film surface is a total (on both sides of the film) 6-20 g per m2 of film surface.