JPH04501456A - Method and device for forced heat transfer between objects and gases - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Method and apparatus for forced heat transfer between objects and gases The present invention relates to methods and apparatus for forced heat transfer between objects and gases. The present invention relates to a method and apparatus for forcing heat transfer between a gas and a surrounding gas.

Forced heat transfer sets the surrounding gas into an oscillating state caused by low-frequency, stationary sound waves. This is achieved by placing an object in the area of maximum vibration in this stationary sound wave. . 1. Heat transfer, for example when heat is transferred from a warm object to the air flow surrounding it. The fundamental problem in gas flow is that the heat transfer efficiency per unit area from the object to the gas flow is low. The problem is that the flow rate is insignificant. A large amount of gas flow rate is required to obtain a large heat transfer effect. , which requires a large amount of airflow. However, at this time the empty The temperature rise in the air is slight. Large amounts of air flow increase cooling costs and As a result of the large temperature increase, little of the energy of the heated air is available.

Zhurnal Pr1kladnoi Mekhan in September/October 1981 iki i Tekhni-chesko i (Brikranoi Mechanical Engineering Jar) Vol. 5, pp. 67-72, by V., B. Reppin, "Syring by low frequency vibration" From the description of ``Heat Exchange in the Heat Exchanger'', heat transfer is improved by generating a sound field in the gas. It is already known that it can be done. Also, if this sound field consists of low frequency range, it will be more effective. It is also known that

・ Forced heat transfer is calculated from two parameters: sound pressure and particle velocity in the sound field. It is clear that it is the particle velocity that provides. Also, heat transfer is caused by particle velocity. It is also clear that it increases with increasing temperature. Low frequency sound to heat or cool objects Until now, the traditional methods of using has a sufficiently high particle velocity over the entire surface of the object to be cooled or heated. This is because there was no effective method or device for producing such sounds.

It is an object of the present invention to solve the above problems and to provide a method for transferring gas from an object to the surrounding gas per unit area. The object of the present invention is to realize a method and a device for transmitting a high thermal effect. object table Instead of increasing heat transfer by drawing gas onto a surface at high velocity, forced heat transfer is achieved by applying low frequency vibrations to the surrounding gas.

In order to make the invention more clear, a device for cooling the hot wire coming out of the wire rolling mill will be described. An example and an example of cooling a baked cement ingot will be described below. Of course However, the invention encompasses other embodiments of the method and apparatus.

The steel wire has a temperature of approximately 850°C when it comes out of the rolling mill, and this is Must be cooled to 300°C. Such cooling typically involves many steps. Use. According to one method, the wire is formed into a spiral with a diameter of about 1 m and is placed on a roller controller. Place it on the conveyor and transport it forward at a speed of approximately 0.5 m/s, and at the same time transport the Multiple large fans placed close to the conveyor blow cooling air onto the wires. place In order to cool down to the desired temperature, a cooling process distance of approximately 60 m is required.

The disadvantages of the above conventional methods are that the equipment is expensive and extremely large. , and a large amount of airflow must be introduced into the premises, and such work requires considerable In addition to consuming power, they also change the temperature and raise dust into the atmosphere. This may be accompanied by environmental disadvantages. Other disadvantages are from a metallurgical point of view , the cooling is not always sufficiently rapid and uniform, and the high-temperature wire The overall thermal effect is lost.

Features and aspects of the invention can be found in the following brief description of the accompanying drawings and description thereof. be more easily understood.

Figure 1 shows a solid body within a standard air stream.

Figure 2 shows a solid body within an air stream that is exposed to an infrasound field.

Figure 3 shows a metal wire cooling device using low frequency sound.

Figure 4 shows a cement sintered ingot cooling device that uses low-frequency sound.

As mentioned above, when a gas is moved back and forth by a steady sound wave generated in the gas, Forced heat transfer is achieved between the surface of the object and the surrounding gas. Figure 1 shows the air flow A solid body is shown at temperature T, exposed to. Particles in the airflow are shown as dots and plotted over time. Let the position of the air particle at multiple points change to t, ~t.

Indicated by The temperature of the air stream is T before passing the solid and T2 after passing the solid. Ru. Figure 2 shows the same solid body exposed to the same airflow, but this airflow is very low. Under the influence of frequency sound waves. In Figure 2, air particles at different points at different times The positions are indicated by t1 to t7. As is clear from the diagram, each air particle passing through the solid The pulsating airflow caused by infrasound causes the air to pass through the air not once but multiple times. It becomes. Air particles pass through a solid if the solid is hotter than the air stream Each time it gradually absorbs heat, the temperature of the solid decreases accordingly. In this way Forced heat transfer is obtained.

In a part of a stationary sound wave, the vibration velocity of the gas, so-called particle velocity, is large, and the pressure The change in force, so-called sound pressure, is minute.

In other parts, the vibration speed of the gas is low and the pressure change is large. at a specific point In this way, both the particle velocity and the sound pressure change with time, which is the ideal situation. exhibits a sinusoidal vibration. The maximum values of particle velocity and sound pressure are both for each vibration. is indicated by the amplitude of In general, the amplitude of the particle velocity is at its maximum value, i.e. the so-called When the particle velocity reaches its antinode, at the same time the amplitude of the sound pressure reaches its minimum value, that is, the so-called sound pressure It presents a section of

From the above, the particle velocity should be as high as possible to obtain maximum forced heat transfer. It is desirable that In a stationary sound wave, the point where the amplitude of particle velocity is at its maximum level There are several points. For stationary sound waves with a length equivalent to 174 wavelengths or 172 wavelengths In this case, the particle velocity amplitude has a maximum value at only one point. Therefore, as much as possible In order to obtain a large forced heat transfer, the surface where the heat transfer occurs can be made to be the antinode of the particle velocity. need to be placed in close proximity.

In the method according to the invention, forced heat transfer between a solid or liquid body and a gas is , as shown in Figure 2, a steady low frequency sound wave is generated by one or more sound wave resonators. Therefore, there is a practical limit. In this specification, low frequency sound waves are defined as 50Hz or lower. means the frequency of 501 (The reason why frequencies above z are not targeted is that The wave resonator has such small dimensions as to render the device incapable at high frequencies. There are many things. Since plosive sounds disappear at even lower frequencies, it is preferable to A frequency of tlz or lower should be used. At this frequency, the interference is It is considered to be extremely small. The sound wave resonator is a half-wavelength of the generated low-frequency sound wave. Other types of acoustic resonators can also be used, although preferably of comparable length. It is. The low-frequency sound waves are transmitted through a so-called exci-gauge placed at the antinode of the sound pressure in the resonator. This is obtained by generating air pulses with an exigator. stomach In this specification, the term "guzigator" refers to a point in the resonator where high sound pressure is distributed. used to refer to the part of an infrasound generator that generates particle velocities. child Regarding this, see, for example, Swedish Patent No. 446157 and Swedish Patent No. Patent Application No. 8306653-0, No. 8701461-9, No. 8802452- See No. 6. Somewhere in the resonator, an antinode of particle velocity occurs simultaneously with a node of sound pressure, At this point, the resonant tube can be opened. The surface on which the above heat transfer is to occur is this Proceed forward through the opening. Therefore, this surface is then exposed to the above-mentioned stationary low-frequency sound waves. is placed at the antinode of the particle velocity.

A steady air flow flows through the resonant tube and a portion of this air flow exits the exigator. The other part is derived from the driving air that flows into the opening through which the heat transfer surface passes. Derived from Qi.

The use of specific cooling blowers is also possible. When the above surface passes through the resonant tube, Vibrating airflow generated partly by steady airflow and partly by steady sound waves blown away by.

If the amplitude of the particle velocity of the sound wave is significantly larger than the amplitude of the velocity of the steady air flow, and If the vibration amplitude of the sound wave is significantly larger than the thickness of the above surface, air is the medium. The same group of elements passes over the surface several times. This ensures that only steady airflow The air is heated or cooled more fully than when blowing over the surface. This conclusion As a result, an even greater heat transfer than in normal conditions occurs in the above table for a given time. Occurs between the surface and the air.

associated with the use of superimposed air effects found in the sound pressure nodes of stationary sound waves. One advantage is that this is a relatively simple way to achieve air vibrations. It's there. Another advantage of using stationary sound waves is that they require high velocities of vibrating air. The reason is that it is only the point where the heat transfer surface is located. Other than this method , high-speed air only involves friction loss.

Hereinafter, an apparatus for carrying out the method according to the present invention will be described with reference to the embodiment shown in FIG. This will be explained in more detail below. FIG. 3 shows a steel wire cooling device.

The low frequency sound is one or more low frequency sounds consisting of an exigulator part and a resonator part. Produced by a sound generator. Inside the resonant tube, the steady sound wave is the sound with the lowest sound pressure. Occurs indicating pressure nodes. The resonant tube has an opening in which this group of nodes is arranged; The opening allows the wire to pass through the resonant tube and thereby eliminates the effects of infrasound waves. Designed to allow exposure of the wire to the received cooling air.

3 shows in detail the device through which the steel wire to be cooled can be passed along the cooling table 1. Shown below. The steel wire is exposed to low frequency sound waves on a cooling table. acoustically this The device is essentially an intermediary system. Steel wires should be placed on roller conveyors according to standard handling. cooling surface on a plane perpendicular to the paper plane of the drawing. is sent forward at a constant speed across the cable. Two tubular resonators 2 and 3 are placed in a tape the open ends onto the table. These resonators are Preferably, the length corresponds to 174 wavelengths of the sound waves to be generated. each resonator A so-called ejector 4.5 is arranged at the other end of each. This exigator is of the type disclosed in Swedish patent application no. 8802452-6. stomach. The ejector 4.5 together with the resonator 2.3 forms an infrasound generator. twin The other excipator 4.5 has a 180° phase delay between each exigator during operation. As a result, they are motor driven in an interlocking manner by the same drive shaft. Each igu Since the digator operates in opposite phases, stationary sound waves of the same frequency are generated in each resonator. Occur. As a result, two 174-wavelength resonators are combined, and each resonator is form one resonator of 172 wavelengths having the same resonant frequency as the resonant frequency of Generate one common stationary sound wave.

Cooling air is supplied by a cooling blower 12. The blower 12 has two resonators. The cooling air is conveyed to the cooling table via two ducts 7.8 arranged between them.

Each of these ducts has a downward radiating section in the wall common to each resonator tube; A radiating section is arranged in the lower part of the tube of each resonator. The nose part 9 consists of two resonance tubes. Located between each lower part and below the outlet of the cooling air duct of each resonant tube be done. The nose portion is designed so that its cross-sectional shape is conical or other similar shape. It is preferable that This nose section runs along the lower part of each resonant tube and between them. It spreads out as an overhanging protrusion. The upper end of the conical nose is connected to each cooling air duct. by being fixed to a wall common to both sides and the curved part forming an extension of this wall. The wall will be split into two. Due to the action of the nose, the air is exposed to low frequency sounds. Effective cooling airflow characteristics are obtained at the bottom of the tube. This air flow is further To enable. sibilance is produced by the sound particle velocity near sharp edges. A common wall between each cooling air duct and each resonant tube to reduce the risk comprises a curved plate 10.11 on the inside of this wall located inside the cooling air duct. be able to. The nose portion 9 has a substantially flat bottom surface facing the cooling table. , This causes the cooling air to vibrate back and forth along the bottom of the nose, causing the cooling table and Most of the steel wire placed above it cools more than it would without the nose. exposed to air. In addition, the steel wire moves forward in a recumbent spiral shape. has the advantageous effect of being exposed to more intense cooling at the outer edges of the table. is obtained. At the outer edge of the table, the steel wire is more tightly wound, but Therefore, the wire requires a greater cooling effect in order to have uniform quality. .

The warmed cooling air is supplied, for example, by a fan 13 installed below the cooling table. will be removed. The amount of heat effect can be determined by various methods, such as passing it through a heat exchanger. taken out and used for a specific purpose.

To further increase the cooling effect, water is placed in the cooling air close to the relevant cooling area. It can also be sprayed.

Instead of using cooling air to handle the thermal effects emitted by an object, cooling Convection surfaces such as pipework containing flowable coolants such as water, ammonia, or Freon. , may also be located in close proximity to the cooling area. This pipe device is part of the heat exchange system. By making the parts configurable, the heat extracted from the object can be utilized in the same way. Can be done.

FIG. 4 shows, for example, forced cooling of a high-temperature cement sintered ingot 20 moving forward on a conveyor belt. An example related to this is shown below. This device does not constitute an acoustically closed system. others In this respect, this device operates similarly to a steel wire cooling device. The difference is that each two resonators 21, 22 with excipitators 23, 24 and motors 25, This is because it is placed below the conveyor belt that carries the baked ingots forward. exposed to heat transfer When the surface to be transported is located at the antinode of the particle velocity, this surface is Configure obstacles. In this case, the cement ingot is smaller than the steel wire shown in Figure 3. It becomes a big obstacle. If the impedance becomes excessive, this is the resonant tube It is expressed as the sharpness of the resonance decreases, that is, the amplitude of each antinode and node of the particle velocity decreases. It means less relevance. Long dimension resonance in situations with large losses It will be seen that there is no reason why the tube should generate stationary sound waves. Exigator The length of the resonant tube can be shortened by placing it closer to the antinode of the particle velocity. I can do it.

The open resonator in the above embodiment is a case in which the resonator opens outward, that is, the resonator It is accompanied by an extreme decrease in the amplitude of the particle velocity at the opening of the vessel. Parable 1/ Even if a four-wavelength resonator is used, the antinode of the particle velocity still remains at the open end of the resonator. exists and is difficult to identify. On the other hand, the sound pressure velocity is It maintains a sinusoidal waveform whose frequency matches the amplitude of the particle velocity without being affected by the diameter. did Therefore, it is accepted that the region where maximum heat transfer is obtained is the region where the volume velocity has an antinode. It is more appropriate and easier to do so.

In each of the above embodiments of the present invention, forced heat transfer is shown only in the form of a cooling process. However, the present invention, of course, does not require forced heat transfer such as freezing, heating, drying, etc. It can also be used in other types of processes. Other field applications include extruded aluminum cooling of aluminum or plastic exterior.

Fig, 2 Submission of translation of written amendment Fig, 4 (mark FF?i!8 in 1849) May 1, 1991

Claims (24)

[Claims] 1. Forced heat transfer by sound between the surface of a solid or liquid object and the surrounding gas 1. A method of carrying out the invention, characterized in that said sound consists of a low frequency standing sound wave. 2. 2. The sound wave according to claim 1, characterized in that the sound wave has only one antinode of volume velocity. the method of. 3. locating the surface within a stationary acoustic wave region located close to an antinode of the volume velocity; The method according to claim 1 or 2, characterized in that: 4. The dimensions of the object in at least two directions are greater than 1/4 of the wavelength of the sound wave. 4. A method according to claim 1, characterized in that: 5. the object has a total dimension significantly smaller than 1/4 of the wavelength of the sound wave; moves within the sound wave, according to any one of claims 1 to 4. Method. 6. The surface consists of a portion of the total surface of the object, and is one dimension of the object. is at least 1/4 of the wavelength of the sound wave. The method described in one of the following. 7. The object moves forward through the stationary sound wave, and different surface portions of the object 7. A method according to claim 6, characterized in that the exposure to the sound waves is gradual. 8. The object may be hot rolled steel wire or extruded aluminum or plastic. Claim 7, characterized in that it is made of any object that requires cooling, such as a Method. 9. When heat transfer is a cooling process, the cooling capacity of a gas is According to any one of claims 1 to 8, the increase is caused by evaporation of the body. the method of. 10. The sound waves are transmitted to the outside of a pipe through which a coolant such as cooling water, ammonia, or Freon passes. 9. According to any one of claims 1 to 8, characterized in that it is arranged on a stationary convection surface in a plane. Method described. 11. the tube forming part of a closed tube arrangement connected to a heat exchange system; 9. A method according to any one of claims 1 to 8, characterized in that: 12. Claims using a low frequency sound generator comprising an ejector part and a resonator part 1. An apparatus for carrying out the method according to 1, wherein the low frequency sound is applied to the resonator part. Provide an aperture located in the region where the wave exhibits an antinode of volume velocity, and through the aperture force heat A device characterized in that it advances said object to be subjected to transmission. 13. The resonator portion has a length corresponding to 1/4 of the wavelength of the generated low frequency sound. two tubular resonators each having the same resonant frequency; 13. Device according to claim 12, characterized in that it forms a common resonator. 14. The two tubular resonators are each equipped with one ejector, and these ejectors are The gator is arranged so that a common standing sound wave of low frequency sound is generated within the two tubular resonators. 14. A device according to claim 13, characterized in that it operates in antiphase. 15. Each of the tubular resonators is directed away from a respective exigator. close to each other so that each opening of the tubular resonator located at each end communicates with each other. 15. Device according to claim 14, characterized in that they are arranged in contact. 16. The nose portion is placed in the opening between each of the tubular resonators. 16. The device of claim 15, characterized in that: 17. The nose portion has a substantially conical shape with a flat bottom surface, and the nose portion has a substantially conical shape with a flat bottom surface. A claim characterized in that the cooling air affected by the low-frequency sound flows along the surface. The device according to item 16. 18. one or more individual cooling air ducts disposed between each tubular resonator; According to any one of claims 13 to 17, the cooling air is supplied by equipment. 19. The nose portion includes the tubular resonator in which the cooling air is affected by the low frequency sound. deflecting cooling air into the tubular resonator adjacent to the opening of the tubular resonator. 18. Apparatus according to claim 17. 20. A cooling air flow is provided on an inner surface of each cooling air duct facing toward each resonator. Claim 18 or 19, characterized in that the improvement is achieved by providing a curved plate. equipment. 21. The shape of the outer surface of the tube through which coolant such as cooling water, ammonia, or Freon passes. 21. Device according to any one of claims 12 to 20, characterized in that it is provided with a flow surface. 22. said tube forming part of a closed tube arrangement connected to a heat exchange system; 22. The device of claim 21, characterized in that: 23. The object to be cooled is passed through the opening of the tubular resonator by a roller conveyor or core. Claims 12 to 22, characterized in that it is continuously advanced on a conveyor belt or the like. Apparatus according to any one of the above. 24. Claims 12 to 23 characterized in that it is an acoustically substantially closed system. The device according to any one of.