JP2010210105A - Heat exchanger and heat exchange device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat transfer performance of a heat exchanger by suppressing development of a temperature boundary layer on the surface of a heat exchanger fin or peeling or thinning the temperature boundary layer, so as to save energy and the size. <P>SOLUTION: Heat transfer faces which are faces of a heat exchanger performing heat exchange with air or various types of other heat transfer faces require thinning or peeling or suppressing the generation of the temperature boundary layers formed on the heat transfer faces. By further thinning or peeling or suppressing the generation of the temperature boundary layer generated on the heat transfer face by vibration of air, the heat transfer performance of this device can be improved and the size of the device can be reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to heat transfer of heat exchanger fins that exchange heat with air or devices that exchange heat with air via various heat transfer surfaces, which are provided in air conditioners, low-temperature equipment, hot water supply equipment, etc. The present invention relates to a technique for improving heat transfer performance by suppressing separation or development of a temperature boundary layer formed on these surfaces on the surface.

In the refrigeration cycle system, the heat transfer performance is expected to be improved by suppressing the separation or development of the temperature boundary layer formed on the surface of the heat transfer fin that exchanges heat with air. If the heat transfer performance is improved, the efficiency of the entire apparatus will be improved, and the heat exchanger will be made more compact.

The temperature boundary layer has a structure that thickens from the fin tip toward the downstream in the air flow direction, but in order to suppress the development toward the downstream, for example, a heat exchanger fin has a slit structure There is an example in which the development of the temperature boundary layer is prevented (for example, see Patent Document 1), and the temperature boundary layer is thinned or peeled off by vibrating the fins and disturbing the air flow between the fins. (For example, refer to Patent Document 2).

JP-A-8-327270 (FIG. 1) Japanese Patent Laid-Open No. 48-38555 (FIG. 1)

In the conventional method, fins are processed by adding slits, etc., to the fins, and the fins are vibrated. In addition, vibrations are transmitted to the entire heat exchanger to generate noise, and strong vibration elements are required to vibrate the fins. It was.

This invention vibrates the air flowing through the gap between the heat transfer surfaces, or disturbs the air blown from the blower to the heat exchanger to thin or exfoliate the temperature boundary layer on the surface of the heat transfer surface. The purpose is to suppress the development and improve the heat transfer performance, leading to the improvement of the performance of the device and the miniaturization.

The heat transfer surface according to the present invention is a heat exchanger for exchanging heat with air, or other various heat transfer surfaces, and the temperature boundary layer formed on the heat transfer surface is thinned or peeled off or development is suppressed. Targeting the necessary surface, the thermal boundary layer generated on the heat transfer surface is made thin by the vibration of air, or it is possible to improve the heat transfer performance of the device and reduce the size of the device by peeling or suppressing the development. To do.

According to the present invention, the temperature boundary layer generated on the heat transfer surface is thinned by air vibration, or peeled off or development is suppressed, heat transfer performance is improved, and the performance of the device can be improved, leading to energy saving.

It is a block diagram of the air conditioning machine which shows Embodiment 1 of this invention. It is a figure showing the temperature boundary layer which arises in the wind direction and fin surface which hit the fin which shows Embodiment 1 of this invention. It is the figure which showed the heat exchanger which has the sound wave generator which shows Embodiment 1 of this invention, and a reflecting plate. It is a graph showing the relationship between d and d 'shown in Embodiment 1 of this invention. It is the figure which showed the fan and fin tube type heat exchanger which are shown in Embodiment 2 of this invention. It is the figure which showed the several fan using the several fan shown in Embodiment 2 of this invention, a fin tube type heat exchanger, and a wind tunnel. It is the figure which showed the fan shown in Embodiment 2 of this invention, the rotary body between a fan and a fin tube type heat exchanger, and a fin tube type heat exchanger. It is the figure which showed the fan shown in Embodiment 2 of this invention, the ventilation guide between a fan and a fin tube type heat exchanger, and a fin tube type heat exchanger.

Embodiment 1.
The structure of Embodiment 1 of this invention is demonstrated using the fin tube type heat exchanger currently widely utilized for the evaporator of a freezing apparatus or an air conditioner. FIG. 1 shows a fin-tube heat exchanger. The fin tube type heat exchanger mainly includes a plurality of heat exchange fins 11 and a plurality of heat transfer tubes 12. A plurality of fins 11 are laminated at a predetermined interval, and heat transfer tubes 12 are provided so as to penetrate through holes provided in the fins 11. For example, in a vapor compression type air conditioner, the refrigerant in the apparatus is compressed by the compressor and flows into the condenser at high temperature and pressure. The refrigerant dissipates heat in the condenser to become liquid refrigerant, and then expands by the expansion means to become a gas-liquid two-phase refrigerant. The refrigerant in the gas-liquid two-phase flows into the heat transfer tube 12 of the finned tube heat exchanger shown in FIG. 1, and the refrigerant is vaporized in the heat transfer tube 12, so that heat is absorbed from the surrounding air through the fins 11.

In the above apparatus, in order to efficiently exchange heat between the air and the fins 11, the air is sent to the fins 11 by the evaporator fan substantially in parallel. In this description, hot and cold heat is supplied from a heat source by a natural refrigerant such as a chlorofluorocarbon system or carbon dioxide gas that is circulated in the heat transfer tube 12 by a compressor or the like in a refrigeration cycle as a primary refrigerant, and into the air that is a secondary refrigerant. Although a configuration for releasing or sucking heat will be described, each refrigerant may be water or ammonia. Furthermore, as a heat exchanger, we will explain the structure of a heat exchanger that transfers heat with air using flat fins fitted to a tube that is a fin tube type, but there is no fin and the tube itself is a parallel heat transfer surface. Naturally, the effects of the present invention can be produced even in various configurations such as corrugated fins.

FIG. 2 shows a temperature boundary layer generated on the fin surface during the heat exchange between the air sent by the blower provided facing the heat exchanger and the refrigerant in the tube through the fin. For simplicity, the fin 21 is a flat plate and does not have a slit or the like, but it is natural that the effect of the present invention can be obtained even if a slit is provided. 2A is a view of the fin structure of the heat exchanger as viewed obliquely, FIG. 2B is a plan view of the fin, and FIG. 2C is an explanatory view in which a laminar flow is generated in the fin by the flow of air.

Although heat cannot be exchanged with the fins 21 at positions sufficiently away from the fins, the air 22 near the fins 21 can exchange heat with the fins 21. The range in which heat can be exchanged is the temperature boundary layer 23, and the thickness depends on the wind speed, air temperature, fin temperature, etc., but at the wind speed (up to 1.0 m / s) used in general air conditioners, the temperature boundary layer of laminar flow is It is formed.

The thickness d of the temperature boundary layer of the laminar flow is given by the following equation using the Reynolds number Re of air, and increases as the distance x progresses downstream as shown in FIG.

In the air conditioner, Re is about 200 to 300, and the temperature boundary layer is about 0.5 mm at a position about 10 mm from the tip.

In the temperature boundary layer formed in this way, the heat flow by heat conduction is dominant, and the heat flow from the fin to the air is proportional to the temperature gradient (Ts-Ta) / d in the temperature boundary layer. Here, Ts is the fin surface temperature, and Ta is the air temperature outside the temperature boundary layer.

In other words, when a laminar boundary layer is formed, the larger the temperature gradient in the temperature boundary layer, the larger the heat exchange amount. For that purpose, it is important to make the temperature boundary layer thinner (d smaller). .

For example, as shown in FIG. 2C, the upstream fin tip portion 24 has a thinner temperature boundary layer than the downstream portion. Therefore, if the fin surface temperature is uniform throughout the fin, the tip portion 24 has a larger amount of heat exchange than the downstream portion. This effect is called the fin leading edge effect.

In order to acquire this leading edge effect more on the fins, the fins are subjected to shape changes such as cutting and raising to suppress the development of the temperature boundary layer, and the leading edge effect is provided at the tip of each cutting and raising to exchange heat. The aim is to increase the amount of heat exchange in the entire vessel.

From the above, the performance improvement of the heat exchanger can be expected by suppressing or thinning the development of the temperature boundary layer formed on the fin surface or by peeling it. In the following, a method for suppressing or thinning the temperature boundary layer using air vibration, or making it peel off will be described.

FIG. 3 is a diagram for explaining the principle of the present invention, and is a conceptual diagram using a sound wave generator as a technique for applying vibration to the air on the fin surface. As shown in FIG. 3 (a), the heat exchanger is made of a metal that totally reflects the sound wave with the sound wave generator 31 perpendicular to the wind direction that flows from the fan of the blower and across the heat exchanger. A reflection plate 32 is provided to vibrate the air on the fins using sound waves.

When the sound wave generator 31 is driven at a certain frequency, air vibrations propagate from the device 31 toward the fins 33. The air on the fin surface is vibrated in addition to the uniform flow sent from the fan. 3B is a front view, and FIG. 3C is a side view in which vibration is applied to the air passing between the fins, which are heat transfer surfaces provided in parallel, by sound waves.

When the air on the fin surface is vibrated, the temperature boundary layer formed on the fin surface is disturbed and affects the downstream development of the temperature boundary layer.

Since this effect is considered to be proportional to the vibration energy generated from the sound source, it is important to generate a stronger sound wave from the sound source. For this purpose, the reflection plate 32 is used, the distance between the sound wave generator 31 and the reflection plate 32 is measured in advance, and the sound source is driven at the resonance frequency assumed from the distance, so that large amplitude vibrations are generated on the air on the surface of the fin 33. Can be given to. In addition, since the normal fin tube type heat exchanger is contained in the housing, the reflecting plate may be omitted and the housing may be used instead of the reflecting plate. A rigid housing simply reflects sound waves and does not vibrate and generate noise.

Even if a given frequency is not a single frequency but a continuous frequency in a predetermined range is used, for example, an effect can be expected to suppress the development of the boundary layer. In other words, the air in the gap between the heat transfer surfaces is vibrated together with the sound wave that is continuously shifted over the upper and lower frequencies of the center frequency and reflected by the reflecting plate.

The temperature boundary layer d ′ generated by vibration is given by the following equation using the thermal diffusion coefficient a of air and the angular frequency w, and is inversely proportional to the frequency.

The relationship between d ′ and d is shown in FIG. However, using Re = 300 and x = 5 mm, d = 0.28 mm. Further, a is a value of air at 20 ° C. a = 22.1 mm ² / s.

From FIG. 4, d ′ becomes larger than d at a frequency of 100 Hz or less, and there is a possibility that the amount of heat exchange is reduced by applying vibration. If it is 100 Hz or more, d 'becomes smaller than d, and the amount of heat exchange can be increased by applying vibration. In other words, a frequency of 100 Hz or higher is desirable.

However, since the attenuation due to the propagation of vibration is proportional to the frequency, if the frequency is too high, the vibration applied to the air flowing through the entire fin does not propagate and the above effect cannot be obtained over the entire fin. The above effect is maximized by optimizing the frequency of the sound wave generator.

The position of the sound wave generating device for efficiently obtaining the above effect is not necessarily required to be located directly below the fin because the air on the fin needs to vibrate. The effect is obtained. When the air flows through the gap between the heat transfer surfaces arranged in the vertical direction formed by a plurality of fins of the heat exchanger, the ultrasonic device is perpendicular to the direction of air flow and is not obstructed by the fins. It will be provided in a certain vertical direction.

An example of the sound wave generator is a Langevin type ultrasonic wave generator. This generator is a highly directional generator, and can generate sound waves uniformly over a wide range by using a wide diaphragm. Any generator is effective for the present invention if the air on the fins is vibrated. Further, since the sound wave generator vibrates the air between the heat transfer surfaces rather than vibrating the heat transfer fins, vibration is not transmitted to the heat exchanger and noise can be suppressed. In addition, the sound wave generator can suppress noise by supporting the housing with an elastic body such as an anti-vibration rubber. In addition to flat fins, for example, when corrugated fins are used, it is difficult to transmit vibrations to the fins because both the peaks and valleys are in contact with the heat transfer tubes when the fins are vibrated. The structure of the present invention that vibrates the air flowing between them can be performed without any trouble. In the case of an apparatus in which a primary refrigerant is passed through a heat transfer tube provided in water and the refrigerant is cooled by a secondary refrigerant that is water, the flow of water may be vibrated. It is sufficient to provide a vibration device.

Also, as shown in Fig. 4, the temperature boundary layer can be suppressed to 1 mm or less, so the fin pitch is as narrow as an air conditioner (the fin pitch is about 1.6 mm in a normal air conditioner). The effect can be expected.

Embodiment 2.
The structure of Embodiment 2 of this invention is demonstrated using the fin tube type heat exchanger currently widely utilized for the evaporator of a freezing apparatus or an air conditioner. In order to efficiently perform heat exchange between air and fins, the fin-tube heat exchanger sends air to the fins using a fan of a blower.

In a heat exchanger that is not devised such as a slit, the air flow between the fins is a laminar flow in a general air conditioner or the like. When the flow becomes turbulent, the heat exchange between the fins and air greatly changes its form.

In laminar flow, heat transfer is dominated by heat conduction and the temperature gradient determines its magnitude. On the other hand, in turbulent flow, heat flow generated by irregular motion of turbulent vortices is generated between fins and air. Due to this effect, in the turbulent flow, the heat conduction is dominant near the fin, and the turbulence of the wind is dominant as the distance from the fin increases.

From the above, heat transfer can be promoted by making the flow turbulent, that is, by disturbing the flow and stirring the fin surface air. That is, the thickness of the laminar flow can be reduced by pulsating the air flow to make it turbulent, and the heat transfer can be further increased by disturbing the flow and stirring. The following describes how to disturb the flow by devising the blower fan attached to the evaporator and condenser.

FIG. 5 shows the relationship between the heat exchanger and the fan. The normal fan 51 is driven by a motor 52 and rotates at a rotation speed set so that fan work given by input voltage and current to the fan motor is constant, for example, 1000 rotations. Here, it is possible to change the uniform air flow by changing the number of rotations of the fan by dropping or increasing the number of rotations of the fan every arbitrary time, for example, plus or minus 100 rotations. When controlling the motor input so as to achieve the set number of revolutions, a change in the wind speed and the amount of air is performed together with control to obtain the set number of revolutions by turning off the input of the semiconductor switch circuit of the motor control device 53 at intervals. Can also save energy when waking up. When the wind speed is low, the time interval for changing the rotation speed of the fan is short, and when the wind speed is high, the time interval is slow, and the air flow is likely to be disturbed.

This affects the development of the temperature boundary layer and is expected to improve heat transfer performance.

In addition, as shown in FIG. 5 (c), fan rotation is performed by attaching a fan direction rotating device 54 that changes the direction of the fan by a small constant angle by a motor so as to periodically change the direction of the wind from the fan in the vertical direction. By this, periodic vibration (pulsation) can be given to the air flow, and the heat transfer promotion effect described above can be aimed at. The fan direction rotating device 54 supports a shaft in the horizontal direction rotatably on a fan leg that supports the fan from the lower part by a bearing, and an integrated structure of the fan and the motor for driving the fan is fixed to the shaft. In the structure, the shaft is rotated in the vertical direction by a motor provided so as to change the angle provided at the shaft end in a range of 20 degrees, for example. Furthermore, since the fan direction rotating device 54 can be rotated left and right, the fan can be moved up and down and left and right, and the heat transfer can be further increased by further disturbing the flow and stirring.

As shown in FIG. 6 (a), if a structure is provided in which a plurality of fans are provided for one heat exchanger, not only the fan can be miniaturized, but also the air flow can be disturbed throughout the heat exchanger. Heat transfer characteristics can be improved. For example, each fan motor 62 is independently controlled by an inverter 63 so that the rotational speed of each fan is different, or the direction of air flow from each fan to the heat exchanger is changed, so that the air flow from each fan is heated. In addition to supplying pulsation to the exchanger, the air flow on the surface of the heat transfer surface can be disturbed by interfering with each other to further improve the heat transfer coefficient. The fans shown in FIG. 6 (b) are provided at positions separated from each other by the radius of rotation, and a wind tunnel 64 for partitioning the fans is provided so that wind interference between the fans does not affect each other. The fan is installed on the exit side of the wind tunnel, and the suction side of the wind tunnel extends long so as to cover the fan motor. Even if the rotation speed of each fan is different, another fan sucks the air from one fan. The structure is designed to prevent interference and prevent adverse effects on the rotational speed, increase the reliability of the motor and extend its life. In addition, the fan direction rotating device may be set by the control device such that the direction of the fans provided in parallel is moved away from each other or the other fan is moved closer to the one fan side when the other fan is moved away. . The fan is selected from two or more considering the air distribution to the heat exchanger. In addition to the fan motor, the motor of the drive device such as the compressor of the heat pump apparatus used in the present invention is a DC using a structure in which rare earth magnets are provided in one circle, or a permanent magnet such as a plastic magnet mixed with powder magnets. A brushless motor is used, and the efficiency of the inverter can be improved by using SiC for the element in half wave or full wave.

As an embodiment of the turbulent flow generation means, a rotating body 73 is provided between a fan 71 and a heat exchanger 72 as shown in FIG. Means for disturbing the flow to the will be described.

For example, the flow can be disturbed even if the rotating body 73 is rotated in the same manner by interweaving the rotating body 73 with a triangle or a polygon. In addition, it is necessary to devise the rotary body 73 so that the ventilation resistance and noise by the rotary body 73 may be reduced. For example, the rotating body 73 in FIG. 7 is provided close to the air suction side of the heat exchanger, and is attached to a shaft provided in parallel with the heat exchanger. The rotating body is rotated by air blown from the fan, the shaft is fixed and the bearing is provided between the shaft and the rotating body, or the shaft and the rotating body are fixed and provided at both ends of the shaft, and supported by the housing. Rotation is enabled by the bearings made. As this bearing, a ball bearing, a metal bearing, or the like is used.

As another embodiment of the turbulent flow generation means, as shown in FIG. 8, a wind regulation guide 83 for determining the wind direction is provided between the fan 81 and the heat exchanger 82, and this wind regulation guide is at most several millimeters to several tens of millimeters. The following short flat plates are provided in parallel with the heat exchanger fins, and the pitch of the flat plates is equal to or greater than the fin pitch and up to several fin pitches. Reduces road loss. The air flow on the fin surface can be disturbed by changing the air flow by shaking the guide 83 periodically or instantaneously by the ultrasonic vibrator 84 or the like.

According to the present invention, it is possible to suppress the development of the temperature boundary layer generated on the surface of the heat transfer fins or stir the air in the vicinity of the temperature boundary layer and increase the amount of heat exchange between the fins and the air. As a result, the performance of the apparatus is expected to be improved, energy saving can be expected, and the apparatus can be miniaturized.

By utilizing the present invention, the development of a temperature boundary layer formed on the surface of a heat exchanger that exchanges heat with air, or a device that exchanges heat with air via various heat transfer surfaces, or thin, Alternatively, the performance of the surface that needs to be peeled off is improved, and the device can be downsized.

The heat exchanger according to the present invention has a plurality of heat transfer surfaces on which heat is transferred from a heat source and a medium such as air passes through a space between the heat sources to exchange heat with the medium. Since the air on the heat transfer surface is vibrated to suppress separation or development of the temperature boundary layer that is formed, the heat pump is used as a heat source, and the heat transfer rate to the secondary refrigerant is improved, so that the apparatus is efficient. be able to.

The heat exchanger of the present invention includes a plurality of fins and heat transfer tubes, a sound wave generator arranged near the heat transfer surface on the surface of the primary refrigerant circulation part, and generates sound waves between the plurality of heat transfer surfaces, Since vibration can be applied to a secondary refrigerant such as air, the efficiency can be improved with a simple structure at low cost.

The blower fan of the heat exchanger of the present invention can be continuously rotated like a commercially available fan or the direction of swinging can be slightly changed by a motor to pulsate a medium such as air blown to the heat transfer surface. Therefore, the efficiency can be improved with a simple structure at a low cost.

The fan of the present invention blows air pulsated to the heat transfer surface by changing the input voltage by the inverter, so that the efficiency can be greatly improved with a simple structure.

The present invention disturbs the air blown to the heat transfer surface by the number of fans or the installation angle or control of the fans arranged to allow a medium such as air to pass through the heat transfer surface of the heat exchanger. It is possible to improve the efficiency with a simple structure without the need to make it.

In the present invention, a rotating body is provided between a heat transfer surface and a fan arranged to allow a medium such as air to pass through the heat transfer surface, the structure of the rotating body is changed, and the medium to the heat transfer surface is changed. Since the flow can be disturbed, the efficiency can be improved with a simple structure without wasting the power of the fan.

The present invention provides a guide for adjusting the flow of air between a heat transfer surface and a fan arranged to allow a medium such as air to pass through the heat transfer surface, and the guide is periodically or intermittently provided by a vibrator. Therefore, the disturbance is generated continuously or intermittently in the flow of the medium, so that the efficiency can be improved with a simple structure without wasting the power of the fan.

The present invention relates to a temperature boundary layer formed on a plurality of heat transfer surfaces for transferring heat from a heat source and exchanging heat with the medium by passing a medium such as air through a space provided between the heat sources. It is a heat exchanger that vibrates the air on the heat transfer surface in order to suppress peeling or development.

The present invention is a heat exchanger that performs air vibration by a sound wave generator that is disposed in the vicinity of a heat transfer surface and generates sound waves between a plurality of heat transfer surfaces.

The present invention is a heat exchange device that changes the operation of a fan arranged to allow air vibration to pass a medium such as air through the heat transfer surface.

The present invention is a heat exchange device that performs air vibration by changing the fan input voltage and changing the rotation speed of the fan.

The present invention is a heat exchanging apparatus that performs air vibration by the number of fans or the installation angle or control of fans arranged to allow a medium such as air to pass through a heat transfer surface.

The present invention is a heat exchange device in which a rotating body is provided between a fan and a heat transfer surface arranged to allow air vibration to pass a medium such as air through the heat transfer surface, and the structure of the rotating body is changed. is there.

In the present invention, a guide indicating the wind direction is provided between a fan and a heat transfer surface arranged to allow air vibration to pass a medium such as air through the heat transfer surface, and the guide is periodically or instantaneously provided by a vibrator. It is a heat exchange device that gives vibration.

11 Fin, 12 Heat transfer tube, 21 Fin, 22 Air near fin surface, 23 Temperature boundary layer, 24 Fin tip, 31 Sound wave generator, 32 Reflector, 33 Fin, 34 Heat transfer tube, 51 Fan, 52 Motor, 53 Motor control device, 54 Fan direction rotation device, 61 Fan, 62 Fan motor, 63 Fan control inverter, 64 Wind tunnel, 71 Fan, 72 Heat exchanger, 73 Rotating body, 81 Fan, 82 Heat exchanger, 83 Air conditioning guide, 84 Vibrator.

Claims (7)

A plurality of heat transfer surfaces for transferring heat from the heat source and exchanging the heat with the medium by passing a medium such as air, and the heat transfer surfaces arranged at intervals in the vicinity of the heat transfer surface An air vibration means for vibrating the air between the heat transfer surfaces, wherein the air is vibrated from a direction substantially perpendicular to the heat transfer surface. The heat exchanger according to claim 1, wherein the air vibration means is a sound wave generator. The heat exchanger according to claim 1 or 2, further comprising air vibration reflection means sandwiching the heat transfer surface on a substantially opposite side of the air vibration means. The fan according to any one of claims 1 to 3, further comprising: a fan that blows air to the heat transfer surface; a motor that drives the fan; and a motor control unit that controls a rotation speed of the motor. Heat exchange device. A plurality of heat transfer surfaces for transferring heat from the heat source and allowing a medium such as air to pass through to exchange heat with the medium; a fan for blowing air to the heat transfer surface; and a motor for driving the fan; And a fan direction rotating device for changing the angle of the fan. 6. The heat exchange apparatus according to claim 4, wherein the number of the fans is two or more. The turbulent flow generation means is provided between the heat transfer surface, the fan, and the heat transfer surface and the fan, and the wind from the fan is turbulent by the turbulent flow generation means. The heat exchange apparatus in any one of 1 thru | or 6.

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