DE1551457A1 - Heat exchanger - Google Patents

Description

Jan Richard de Fries
Zurich / SCIIUEIZ "

Heat exchanger

The invention relates to heat exchangers with a moving heat transfer member and turbulence generators.

For some time now, heat exchangers with moving heat transfer organs have been used known, e.g. B. Ljungström type for power plants, Dow Corning type ceramic cell systems for gas turbines. Two rooms are always surrounded by a moving, usually

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turned, System touches the receive elements in a space heat, move to the other room and emit heat there. These heat exchangers have a higher output per unit volume than stationary exchangers, but are usually more expensive.

Manifold areas of application for heat exchangers have been not yet used for economic reasons; such as air conditioning in buildings and vehicle heating. A heat transfer from the used exhaust air to the fresh supply air lowers the caloric requirement for a given amount of fresh air considerably.

The invention is therefore based on the object simple and to create lightweight heat exchangers that can be combined with other processes if possible and that are inexpensive to manufacture work well even with small temperature differences.

The invention consists in that in a heat exchanger with a moving heat transfer element and turbulence generators the turbulence generators are designed as micro-turbulence generators and flow around them in the area of subsiding turbulence, and that the generators are arranged as a spatial framework and at least a number of them are mutually in the turbulent Area of influence of previously flown around turbulence generators lies.

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The heat exchange between moving media and solid surfaces takes place by transferring the thermal excited state of the molecules to the solid. Should If high heat transfer numbers are achieved, as many molecules of the medium as possible have to come into contact with the solid come. According to the current state of the art, this is achieved in the supercritical flow according to Reynolds' definition, so with full turbulence. The boundary layers to be expected in the laminar area have only very low exchange functions, since essentially only the boundary layer molecules themselves reach the solid surface. So there was no reason to go with the heat-exchanging elements in the area of laminar flow components,

Studies on insect flight and a new type of fan, as well as numerous attempts have led to a way to

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which allows heat exchangers of high power density in the flow area below the fully developed turbulence to construct. It is based on the observation that even well below the critical Reynolds number, an intense Heat exchange is possible if a local turbulence is achieved by microturbulence generators. Such microturbulence generators are found on insects in the form of bristles, croissants, fibers in a variety of forms and are there

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would enable the flight in the laminar area and the detachment to delay the boundary layer so far that the resistance remains in the performance range of the insect. Although this up- '' position is a completely different one, it is related to the present invention, in which the reduction of the friction around the flow is just a beneficial byproduct.

As a microturbulence generator, an intrinsically laminar flow is used Understood body in which the laminar flow comes to detachment. It arises in the direction of the current after one such a body has a vortex (Karman Strait) running through viscous damping decays faster the further one is away from the critical Reynolds number.

In the case of fine fibers in an air flow of 10 m / s, the area of influence is of such a turbulence generator only briefly in the direction of the current, the eddies correspond at most to twice the fiber diameter, the resulting turbulence is limited to a very small field, so that the term "microturbulence generator" used here seems appropriate.

The heat exchanger according to the invention is now physically based on the fact that such microturbulence generators in electricity

direction are connected in series, they are described as bars of a spatial framework, at least partially

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lying in the field of turbulence caused by the flow direction of flow preceding microturbulence generator is caused. The heat transfer reaches very high values under these conditions when the rods themselves act as heat carriers be used. Compared to the calculation carried out for laminar conditions, the measured values are around be a power of ten higher. Of course, the heat capacity of such a fine framework is low in air resistance tiny. The heat exchanger must rotate rapidly or run as a belt. In the tests, a processing time for the Half of a cylindrical, radially flowed through fiber ring selected, which is 12 milliseconds.

It creates a number of side effects, so that occurs through Flow friction around the media on the fibers creates a powerful air flow in a tangential direction; the heat exchanger acts as a fan and in many cases creates a special air flow maintenance facilities dispensable.

The fine rod structure catches foreign bodies and acts as a coarse filter, which is a welcome one for air conditioning units and vehicle systems Side effect is. The strong viscous damping of aerial vibrations in such a system also has sound absorption. result, which is very advantageous for many applications, such as ventilation of rooms with fresh air.

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Another side effect occurs when passing through the heat exchanger flowing media absorb moisture by spraying or condensation in the heat exchanger has arrived. As a result of the large surface, intense evaporation occurs, which is strongly promoted by the microturbulence. This intensive evaporation can be converted into extensive evaporative cooling with the aid of a special circuit of the heat exchanger.

Last but not least, it should be pointed out that the fine framework used acts as explosion protection by adding a chemical Reaction of two media flowing through and mixed in the rotor at normal continuation speed, i.e. not in Basket interior can take place.

The invention is intended to be based on exemplary embodiments with reference will be explained in more detail on the accompanying drawings. In these show:

Fig. 1 ^! a perspective view of a heat exchanger according to the invention;

Fig. 2 is a perspective view of a modified one Embodiment;

Figure 3 is a greatly enlarged view of the material used in the heat exchanger;

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Fig. 4 is a perspective view of another

Embodiment of the heat exchanger according to the invention;
" and

Figure 5 is a schematic flow diagram of the heat exchanger.

Fig. 1 shows a schematic, perspective illustration simple design of the heat exchanger described. The electric motor 1 causes a shaft 2 to rotate counterclockwise offset. The flange plate 3 "and the columns 4 connect the motor housing to the exchanger housing 5. The shaft 2 sets the rotor 8 in rotation. The periphery of the rotor 8 consists of a fine felt-like framework through which air flows.

Inside there
can flow through. The rotor 8 is divided into two halves by the stationary partition 9.

If air now flows in at 13, it passes through the semicircular Channel 1.1, formed by tube 18 and the upper partition 10 (both shown in dotted lines) into the space to the left of the rotor partition 9. It flows through the rotor and is ejected through the diffuser channel 15 in the direction 16.

If air flows in at 14, it passes analogously through the channel 12 and reaches the space to the right of the partition wall 9. It also flows through the rotor 8 and is through the diffuser 7 in the direction 17 launched.

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The ring of the rotor 8 thus runs continuously from one air space to the second air space, with only a small amount of air (approx. 5%) overflows. If there is a temperature difference between the currents, the rotor temperature is lower as a result Mass and high heat transfer always almost to the current temperature, i.e. transports heat from one current to the other,

Measurements on executed machines of this arrangement with a rotor speed of 2 * 500 rpm, a rotor diameter of 150 mm, rotor height 45 mm and a temperature difference of 20 C between the two streams resulted in a difference in the outflow temperatures at 17 and 16 of 8% or 0.8 C, which corresponds to a very good heat exchange. The air pumping effect reaches 84 l / s when the flow exits freely.

Figure 2 shows a similar machine, especially tailored for the purposes of room ventilation. The representation is schematic and in perspective.

The motor 20 drives the baskets 21 and 22 via the shafts 23 protruding on both sides, they rotate in a counterclockwise direction. The baskets 21 and 22 contain on their periphery a fine, permeable framework 24 which, as described, exchanges heat and has an air-conveying effect.

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If air 25 flows in through the dotted slot 26, it arrives into the basket half delimited by the partition wall 26-a and through the rotors 21 and 22 into the outlet channels 27 and 28 and in the direction of the arrows 29 and 30 in the room to be ventilated "

Air flows on the (not visible) rear of the device into the area under the partition wall 26-a and enters the lower one semicircular spaces of the baskets 21 and 22, so it flows through the rotors in the outlet channels 31 and 32 and in the direction the arrows 33 and 34 in the room from which fresh air is taken, generally in the open.

The baskets 21 and 22 take part of the heat of the exhaust air flow and transfer this heat to the mostly colder supply air due to their rotation. In cooled rooms, for example in Summer operation, there is an unconstrained inverse effect, the cool exhaust air cools through the rotating baskets 21 and 22 warm supply air, with this simple arrangement the mixed temperature can be achieved up to the limit of the heat exchange capacity.

The additional effects discussed, such as the noise insulation through the baskets used, the filter effects, the air flow allow the various functions of supply air / exhaust

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Air device very easy to design and make an essential Step above the state of the art, which requires a whole range of individual devices for the same purpose.

In Figure 3, the structure of the heat exchanger is shown. The rods 35, connected in nodes 36 and from the top left Shown illuminated, they form a disordered spatial framework, less than the spaces 37 through which air flows.

The rods 35 act as microturbulence generators. They create a turbulence in the air flowing through, which leads to the next Rods arrives and, as the experiments mentioned showed, achieved excellent heat transfer, although the rods 35, im Considered in terms of Reynolds number, for the usual flow velocities lie in the area below the critical dimensions for fully developed turbulence. By the high ■ speed can be a reduction of the transmission power through the low mass, the experiment was with basket weights carried out by 24 g, avoid completely.

Figure 4 shows a special type of heat exchanger described. For the sake of clarity, the drive motor and the upper end cover have not been drawn. The basket rotates counterclockwise, it is driven by known means. Inside the basket are, by known

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The partitions 39-40, 41-42 and 43-44 are kept stationary in the middle. '' They form six segment-shaped inflow channels that correspond to six diffusers arranged on the circumference of the basket, Inflow 45 with diffuser 46, inflow 47 with diffuser 48, inflow 49 with diffuser 50, inflow 51 with diffuser 52, inflow 53 with diffuser 54 and inflow 55 with diffuser 56. The diffusers are formed by the metal sheets 57-62.

There is now an exchange of heat between all of these six partial flows instead, which enables a number of special circuits.

For example, the warming medium can be fed to the inflow 45, it is fed from the outflow 46 through a suitable curved channel into the inflow 49 and fed back from the outflow 50 from the inflow 53, in order to finally leave the system at 54. The reheated medium is fed at 55, its effluent 56 is fed into the inflow 51, the effluent ^52: NEM influx is supplied 47 to get out of the system to finally at 48 "The two currents are in a counter-current arrangement; the already cooled medium in 53 will only heat the cool medium at 55 by one step via the basket 38, but the already warmed medium from 56 then meets a warmer basket in 51 to experience even more heating in the last step at 47 .

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This circuit is intended to demonstrate that with the heat exchanger according to the invention all known, also very worked out. can achieve the design of the stationary heat exchanger.

As already mentioned, a special application of the heat exchanger is multi-stage evaporative cooling.

If air is supplied at 45 and water is sprayed in, intensive evaporation occurs in the basket 38 and the heat of evaporation is withdrawn from the air flow and the basket. The exhaust air at 46 is now almost saturated. If dry air now enters at 47 without the addition of water, it is cooled by the basket and exits chilled but unsaturated at 48. This air is now fed back in at 49 but with water spray. Again the heat of evaporation is withdrawn, but starting from already lower temperature level of the supply air through the first stage. The exhaust air at 50 is again nearly saturated and becomes like that Air blown away at 46. Dry air entering at 51 is now cooled very strongly, removed at 52 and with the addition of water 53 supplied again. The saturated cold air leaves the system at 54. In a final stage, you can now turn to 55 dry or slightly humidified supply air can be introduced, which from the meanwhile very cold basket 38 to a low temperature

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level is brought and is available at 56. The remaining The cold of the rotor again favors the cooling of the air entering at 45 and so on. It is a regenerative cycle with evaporative cooling, in the case of air liquefaction in a circuit-wise similar form known that here through Use of the heat exchanger according to the invention can be carried out particularly easily and with modest means.

It should also be pointed out that in aerosols, which in a cobr structure as shown in Figure 3 and thrown away over time if the basket is conical are, often considerable heat energies are contained, which by the circulating, having a restraining effect System can also be made useful for heat exchange.

In Fig. 5 the flow diagram of a heat exchanger according to the invention is shown schematically, which is provided in the wall of a room. The temperature prevailing in the room is marked with T ₁ and the temperature of the outside air with T. The air drawn in from the outside T. passes through the foam basket and is released into the room _{at a temperature T 0.} The exhaust air also passes through the foam basket and

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enters the atmosphere with a temperature from T _Q. A test was carried out with an internal temperature T ₁ of 19.4 C and an external temperature T. of 5.5 C, i.e. with a temperature difference of 13.9 C between the indoor and outdoor air.

A measurement showed that the outside air has reached the temperature T ₀

of 13.6 C was heated and the exhaust air was cooled to the temperature Τ ,, of 14.1 C. The temperature difference of the two Air flows after passing the unit was only about 0.5 C.

With this unit 48 l / sec were pumped and from the outside temperature heated from 5.5 C to 13.6 C. The difference of 8.1 C corresponds to about 400 watts / sec., Which were supplied to the air. The same amount of air was evacuated in the same time. The motor consumed about 40 watts / sec., So that the Net energy gain at 360 watts / sec. lay.

The heat exchanger according to the invention can also be used with advantage, for. B. in cold rooms in which fruits such as bananas are stored will find use. In this case, it is possible to cool the air used for ventilation considerably, thus providing the necessary cooling Cooling capacity in the storage room is reduced by about 60%.

The heat that is bound in aerosols that are trapped in the air can be used to increase heat transfer

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through a process that traps the aerosols through the filtering effect of the basket. The aerosols can removed by making the baskets and the foam a frustoconical Get shape, - · The aerosols are transported back to the air inlet duct.

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Claims (10)

PATENT CLAIMS 1.) Heat exchangers with moving heat transfer member and turbulence generators, characterized in that that the turbulence generators are designed as micro-turbulence generators and in the area of subsiding turbulence are flowed around, and that the turbulence generators are arranged as a spatial framework and at least one Number of them is mutually in the turbulent area of influence previously flown around turbulence generators. 2.) Heat exchanger according to claim 1.), characterized in that an organic foam whose membrane surfaces have been removed by a suitable post-treatment, is used as a three-dimensional framework. 3.) Heat exchanger according to claim 1.), characterized in that a loose, consisting of individual fibers and Material glued to individual points of contact of these fibers is used as a three-dimensional framework. 4.) Heat exchanger according to one of claims 1.) - 3.), characterized in that the frictional effect of the 009812/0528 BAD ORlGtNAt spatial framework at the same time to the movement of the heat-exchanging media in the sense of a swirl is applied in the heat exchanging media. 5.) Heat exchanger according to one of "Claims 1.) - 4.), characterized in that the filter effect of the spatial framework to hold back aerosols in the Media is used. 6.) Heat exchanger according to one of claims 1.) - 5.) -, characterized in that evaporation processes are carried out by introducing vaporizable liquids into the spatial structure are subject to heat exchange. 7.) Heat exchanger according to one of claims 1.) - 6.), characterized in that the structure of the spatial framework also acts as a protection against the continuation serves exothermic gas reactions in the flow passing through the heat exchanger. 8.) Heat exchanger according to one of claims 1.) - 7,), characterized in that the framework as a ring (8) 009812/05 28 is formed, separated by a central wall (9) in a multi-flow volute casing (5) rotates. (Pig. I) 9.) Heat exchanger according to one of claims 1) - 7), characterized in that sections of a multi-fluff Spiral housing and a multi-cell partition (2, 4, 6, 3, 3, 7) to build a countercurrent system for the Heat exchange can be used. (Fig. 4) 10.) Heat exchanger according to one of claims 1) - 9), characterized in that the simultaneous effects of Air conveyance, coarse feeding and sound insulation in space Stabvverk is used for the ventilation of interiors by utilizing the exhaust air heat. BATHROOM OWGINAL 0098 1 2 / 052Θ