JP5077926B2 - Heat exchanger - Google Patents

Description

  The present invention relates to a heat exchanger, and more particularly to a heat exchanger that performs heat exchange between air and a heat exchange medium.

Conventionally, as this type of heat exchanger, in a finned tube heat exchanger in which a plurality of heat transfer tubes penetrate through a plurality of fins arranged in parallel, thin slits are processed into fins as a plurality of fins. Using slit fins (for example, see Patent Document 1), using corrugated fins with corrugated irregularities perpendicular to the air flow direction (for example, see Patent Document 2), 30 degrees with respect to the air flow A device using a V-shaped corrugated fin in which corrugated irregularities are provided in a V-shape with an angle (for example, see Patent Document 3) has been proposed. These heat exchangers attempt to promote heat transfer of the finned tube heat exchanger by devising the shape of the fins.
JP 2003-161588 A JP 2000-193389 A JP-A-1-219497

  However, in the heat exchanger using the slit fin and the heat exchanger using the corrugated fin, although the heat transfer rate is improved, the heat transfer rate is higher than the heat transfer rate due to separation of the air flow due to protrusions or cuts and local acceleration. Ventilation resistance may increase. In addition, when using such a heat exchanger as an evaporator of a refrigeration cycle, water vapor in the air becomes dew or frost and adheres to the heat exchanger, and condensate or frost clogs between the slits. In some cases, the flow of water is inhibited.

  In the heat exchanger using the above-mentioned V-shaped corrugated fins, depending on the shape of the V-shaped corrugated irregularities, the heat transfer coefficient may be low or the ventilation resistance may be large. In addition, since the V-shaped corrugation is formed up to the end of the fin, it may be difficult to cut or assemble when forming the fin, the strength of the fin is insufficient, and bending occurs when laminating. In some cases. Further, the fin efficiency is significantly reduced at an intermediate position between the heat transfer tubes and the heat transfer execution distance becomes long particularly at the end portions of the fins, so that the desired performance may not be obtained.

  The heat exchanger of this invention makes it one of the objectives to suppress separation of air flow and local acceleration. Another object of the heat exchanger of the present invention is to improve heat exchange efficiency. Furthermore, it is an object of the heat exchanger of the present invention to reduce the size. Or the heat exchanger of this invention makes it one of the objectives to make formation of a fin easier. In addition, it is an object of the heat exchanger of the present invention to improve the assembly property of the heat exchanger. Another object of the heat exchanger of the present invention is to increase the strength of the fins so that bending does not occur during lamination.

  The heat exchanger of the present invention employs the following means in order to achieve at least a part of the above-described object.

The heat exchanger of the present invention is
A heat exchanger for exchanging heat between air and a heat exchange medium,
A plurality of heat transfer tubes arranged in parallel as flow paths of the heat exchange medium;
An air inflow portion for inflowing air, an air outflow portion for outflowing air, and an air passage extending from the air inflow portion to the air outflow portion intersecting the plurality of heat transfer tubes so as to be capable of exchanging heat are arranged in parallel. A plurality of corrugated fin members stacked on each other;
With
The plurality of fin members are arranged so that an angle formed by an air streamline and a wave in a predetermined range in the direction from the air inflow portion to the air outflow portion is an angle within a range of 10 degrees to 60 degrees. A wave amplitude in the vicinity of a portion forming the air inflow portion and / or the air outflow portion is formed to be smaller than a wave amplitude in a portion forming the passage.

  In this heat exchanger of the present invention, the angle formed by the air streamline and the wave in a predetermined range from the air inflow portion to the air outflow portion is an angle within the range of 10 degrees to 60 degrees. By arranging, it is possible to generate a secondary flow component effective for promoting heat transfer without causing separation in the air flow. Therefore, local acceleration of the air flow can be suppressed and heat exchange efficiency can be improved. As a result, it is possible to reduce the size of the heat exchanger. In addition, by forming a plurality of fin members so that the wave amplitude in the vicinity of the portion forming the air inflow portion or air outflow portion is smaller than the wave amplitude in the portion forming the passage, cutting when forming the fin It is possible to make the heat exchanger easy to install and to improve the assembly of the heat exchanger.

  In such a heat exchanger according to the present invention, the plurality of fin members may be formed to have a flat surface at a portion where the air inflow portion and / or the air outflow portion are formed. If it carries out like this, the cutting | disconnection at the time of forming a fin can be made easier.

  Further, in the heat exchanger according to the present invention, the plurality of fin members may be formed with reinforcing ribs in the vicinity of a portion forming the air inflow portion and / or the air outflow portion. . If it carries out like this, the intensity | strength of a several fin member can be increased and the bending which may arise when it laminates | stacks can be suppressed.

  Further, in the heat exchanger according to the present invention, the plurality of fin members may have a ratio (a / p) between a maximum value (a) of a wave amplitude in each fin member and a fin pitch (p) that is an interval between the fin members. ) Can be 0.15 or more. If it carries out like this, the heat transfer rate of a several fin member can be improved, and the heat exchange efficiency of a heat exchanger can be improved.

  Furthermore, in the heat exchanger according to the present invention, the plurality of fin members may be formed so that an inclination angle of a wave cross section at a portion forming the passage is 40 degrees or more. If it carries out like this, the flow of the air along a wave can be strengthened and the heat transfer rate in a several fin member can be improved. As a result, the heat exchange efficiency of the heat exchanger can be improved.

  In the heat exchanger according to the present invention, the plurality of fin members may be formed with waves so that air flows in a dead water area behind the heat transfer tube in the air flow direction. If it carries out like this, air can be made to flow also into the dead water area of the flow direction back of the air of a heat exchanger tube, and heat exchange efficiency can be improved.

  In the heat exchanger of the present invention, the plurality of fin members may be formed with waves so that a top line connecting the tops of the waves is bent a plurality of times. In this case, the plurality of fin members may be formed with waves such that a bending line connecting the bending points of the top lines of adjacent waves in the predetermined range coincides with the air stream line. it can.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a block diagram showing an outline of the configuration of a finned-tube heat exchanger 20 as an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing an AA section of the finned-tube heat exchanger 20 in FIG. 3 is a cross-sectional view showing a CC cross section of the finned tube heat exchanger 20 in FIG. 1, and FIG. 4 is a perspective view in the vicinity of the CC cross section of the fin 30 of the finned tube heat exchanger 20 in FIG. It is. In addition, FIG. 2 has shown the range from the heat exchanger tube 22a to the heat exchanger tube 22b on the relationship which expands and shows a cross section. The finned-tube heat exchanger 20 of an Example is arrange | positioned substantially perpendicularly to the several heat exchanger tubes 22a-22c arrange | positioned in parallel which make the path | route of a heat exchange medium, and these heat exchanger tubes 22a-22c so that it may show in figure. The plurality of fins 30 are configured.

  The plurality of heat transfer tubes 22a to 22c are parallel and cooling air for diverting or diverting a heat exchange medium, for example, a cooling liquid such as cooling water or cooling oil, or a medium such as a refrigerant gas used in a refrigeration cycle. It is arranged so as to be substantially perpendicular to the flow.

  As shown in FIGS. 1 to 4, the plurality of fins 30 are bent by a plurality of bent ridges 34 indicated by wavy lines in FIG. 1 and a plurality of bent lines indicated by dashed-dotted lines interposed between the plurality of ridges 34. The fins 30 are configured as a plurality of wavy flat plate members formed with valleys 36, and the fins 30 are adjacent to the heat transfer mediums of the heat transfer tubes 22 a to 22 c substantially perpendicularly to the flow direction of the heat exchange medium at equal intervals. It attaches to the heat exchanger tubes 22a-22c so that it may become substantially parallel. Note that the attachment portions 32a to 32c of the heat transfer tubes 22a to 22c of the plurality of fins 30 are formed as horizontal portions without the ridges 34 and the valleys 36 because of the necessity for attachment. In the embodiment, in FIG. 1, the plurality of fins 30 constitute an air inflow portion on the upper side, an air outflow portion on the lower side, and an air passage between the heat transfer tubes 22a to 22c. Is done.

  A plurality of crests 34 and troughs 36 of each fin 30 have an angle γ between a continuous line (dashed line, alternate long and short dash line) and an air flow (streamline) on the air inflow side in a range of 10 degrees to 60 degrees. The inner angle, for example, 30 degrees, is formed so as to be symmetric with respect to the air stream line at the center of the adjacent heat transfer tubes 22a to 22c. Accordingly, the curve connecting the bent portions of the peak portion 34 and the valley portion 36 coincides with the air stream line on the air inflow side. FIG. 5 shows air flow lines when the finned tube heat exchanger 20B is constituted by the fins 30B formed as simple flat plates in which the crests 34 and the valleys 36 are not formed. 6 is a cross-sectional view showing a cross section when the fin 30 is broken along a curve B1-B2 in FIG. 1 connecting the bent portions of the peak portion 34 and the valley portion 36. As shown in FIG. As shown in the drawing, the curved surface B1-B2 surface of the fin 30 is formed in a wave shape in which peaks 34 and valleys 36 appear alternately. Thus, on the air inflow side, the angle γ formed by the continuous line (dashed line, alternate long and short dash line) of the crest 34 and the trough 36 and the air flow (streamline) is an angle in the range of 10 degrees to 60 degrees. The reason why the fins 30 are formed is to effectively generate a secondary air flow. FIG. 7 shows a secondary flow (arrow) of air generated on a flat plate when a uniform flow of air having a small flow velocity is introduced into a corrugated flat plate, and contour lines due to temperature. As shown, a strong secondary flow is generated by the peaks 34 and valleys 36, and a large temperature gradient is generated in the vicinity of the wall surface. In the embodiment, the angle γ formed by the continuous line (the wavy line, the alternate long and short dash line) of the peak part 34 and the valley part 36 and the air streamline is set to 30 degrees in order to effectively generate this secondary flow. is there. If the angle γ is too small, an effective secondary flow cannot be generated in the air flow. If the angle γ is too large, the air cannot flow along the ridges 34 and the valleys 36, and peeling or local Speed increase occurs and ventilation resistance increases. Accordingly, the angle γ formed is preferably 10 to 60 degrees, more preferably 15 to 45 degrees, and more preferably 25 to 35 degrees within an acute angle range in order to generate a secondary air flow. is there. For this reason, in the embodiment, 30 degrees is used as the angle γ formed. When the air flow is small, the main flow of the air flow is kept substantially the same as the streamline in the case of a simple flat plate without the peak part 34 or the valley part 36, and the secondary flow by the peak part 34 or the valley part 36 is maintained. It can be generated effectively. Note that the formed angle γ is not necessarily constant, and the peak portion 34 and the valley portion 36 may be changed to be curved.

  The plurality of crests 34 and troughs 36 of each fin 30 are formed so that air flows in the dead water area behind the heat transfer tubes 22a to 22c on the air outflow side. By carrying out like this, air can be flowed also to the dead water area of the heat transfer tubes 22a-22c back in the air flow direction, and it can contribute to heat exchange.

  As shown in FIG. 4, the inflow portion forming portion 37 that forms the air inflow portion of each fin 30 and the outflow portion forming portion 38 that forms the air outflow portion are flat surfaces as shown in FIG. It is formed so as not to be corrugated by the valley portion 36, and for this reason, it is a peak portion from the portion (center portion) where the air passage is formed toward the inflow portion forming portion 37 or the outflow portion forming portion 38 at the end. 34 and the valley 36 are formed so that the waveform amplitude gradually decreases. By forming each fin 30 in such a shape, if the inflow portion forming portion 37 or the outflow portion forming portion 38 is a cutting portion when the fin 30 is formed, the fin 30 can be easily cut. It can be. For example, a roll cutter or the like can be used for cutting when the fins 30 are formed, and productivity can be improved. Further, clogging due to frost or dust is likely to occur near the air inflow portion of the fin 30, but performance deterioration due to clogging of frost or dust can be reduced by making the inflow portion forming portion 37 flat. Can do. Further, when the finned tube heat exchanger 20 is used for an air conditioner, condensed water is generated on the fins 30 during cooling operation or defrosting operation, but the inflow portion forming portion 37 or the outflow portion forming portion 38 is flattened. By doing so, the condensed water can be discharged well. Further, in the region where the distance from the heat transfer tubes 22a to 22c is large, particularly in the end portion of the fin 30, the fin efficiency is lowered, but the inflow portion forming portion 37 and the outflow portion forming portion 38 are made flat to make the fin A reduction in efficiency can be suppressed, and a high-performance heat exchanger can be obtained. In addition, when the finned tube heat exchanger 20 is used as an evaporator, the drainage property can be improved by making the inflow portion forming portion 37 and the outflow portion forming portion 38 flat surfaces.

  In the embodiment, each fin 30 is defined by the maximum value a (see FIGS. 2 and 6) of the amplitude of the waveform by the crest 34 and the trough 36 and the fin pitch p (see FIG. 2) that is the interval between the fins 30. The amplitude pitch ratio (a / p), which is the ratio, is formed and assembled so as to be 0.15 or more. This is because the heat transfer of the finned tube heat exchanger 20 using the fins 30 of the embodiment in which the waveform is formed by the crests 34 and the troughs 36 in the range where the amplitude pitch ratio (a / p) is 0.15 or more. The rate of improvement (h / hplate) calculated as the ratio of the rate h and the heat transfer rate hplate of the finned tube heat exchanger using fins formed by flat plates on which no corrugations 34 and valleys 36 are formed is 1 Based on the calculation result of .5 or more. FIG. 8 shows an example of calculation results obtained by investigating the relationship between the amplitude pitch ratio (a / p) and the heat transfer coefficient improvement rate (h / hplate).

  In the example, each fin 30 is formed such that the inclination angle α (see FIG. 2) of the corrugated cross section by the crest 34 and the trough 36 is 40 degrees or more. This can strengthen the flow of air along the waveform by the crest 34 and the trough 36 in the range of the inclination angle α of 40 degrees or more, and effectively generate a secondary flow that contributes to heat transfer. Based on what can be. In the range where the inclination angle α is 40 degrees or more, the Nusselt number Nu, the peak portion 34 and the valley portion 36 of the finned tube heat exchanger 20 using the fin 30 of the embodiment in which the waveform by the peak portion 34 and the valley portion 36 is formed. The improvement rate (Nu / Nuplate) calculated as a ratio to the Nusselt number Nuplate of a finned tube heat exchanger using fins formed by flat plates on which no waveform is formed is 1.14 or more. Here, the Nusselt number Nu is a dimensionless number that appears in convection heat transfer, and is expressed as Nu = h · L / k using the heat transfer coefficient h, the representative length L, and the heat conductivity k. FIG. 9 shows an example of an experimental result obtained by examining the relationship between the inclination angle α and the Nusselt number improvement rate (Nu / Nuplate). As shown in FIG. 9, the Nusselt number improvement rate (Nu / Nuplate) increases when the inclination angle α is mainly in the range of 20 degrees to 40 degrees, and then becomes about 1.14 to 1.16. Therefore, in the embodiment, each fin 30 is formed so that the inclination angle α is 40 degrees or more. However, if the inclination angle α is 20 degrees or more, it is desired to improve the Nusselt number Nu to some extent. Therefore, the fins 30 may be formed so that the inclination angle α is 20 degrees or more, preferably 30 degrees or more, and more preferably 40 degrees or more.

  According to the fin tube heat exchanger 20 of the embodiment described above, on the air inflow portion side, the ridge portion 34 is formed on the fin 30 so that the angle γ formed with respect to the air stream line is a predetermined acute angle (30 degrees). By forming the valley portion 36 and the valley portion 36, a secondary flow effective in the air flow can be generated to improve the heat transfer efficiency, and the heat exchange efficiency as a whole can be improved. As a result, the fin tube heat exchanger 20 can be downsized. Moreover, since the crest part 34 and the trough part 36 of each fin 30 are formed in the outflow side of air so that air may flow into the dead water area of the back of the air flow direction of each heat transfer pipe 22a-22c, heat transfer pipes 22a-22c are formed. The air can also flow in the dead water area at the rear of the air flow direction to contribute to heat exchange. As a result, the heat exchange efficiency of the fin tube heat exchanger 20 can be further improved. Further, since waves are formed by the peaks 34 and the valleys 36 on the fin 30, the fins are not cut and raised, and the distance between the fins is not narrowed. Speed can be suppressed.

  Further, according to the fin tube heat exchanger 20 of the embodiment, the peak portion is formed from the portion (center portion) where the air passage of the fin 30 is formed toward the inflow portion forming portion 37 or the outflow portion forming portion 38 at the end. 34 and the valley portion 36 are formed so that the waveform amplitude gradually decreases and the inflow portion forming portion 37 and the outflow portion forming portion 38 are formed to be flat surfaces, so that the inflow portion is formed when the fin 30 is formed. If the part 37 or the outflow part forming part 38 is used as a cutting part, cutting when forming the fin 30 can be facilitated. As a result, the formation of the fins 30 can be made easier and the assemblability of the fin tube heat exchanger 20 can be made better.

  Furthermore, according to the fin tube heat exchanger 20 of the embodiment, the amplitude that is the ratio between the maximum value a of the waveform amplitude due to the crest 34 and the trough 36 of the fin 30 and the fin pitch p that is the interval between the fins 30. By forming the fins 30 so that the pitch ratio (a / p) is 0.15 or more and assembling the heat exchanger, the heat transfer rate of the heat exchanger can be improved as compared with that using flat fins. (H / hplate) can be 1.5 or more. As a result, the heat exchange efficiency of the heat exchanger can be improved.

  In addition, according to the fin tube heat exchanger 20 of the embodiment, by forming each fin 30 so that the inclination angle α of the corrugated cross section by the crest 34 and the trough 36 of the fin 30 is 40 degrees or more, The heat Nusselt number Nu of the exchanger can be 1.14 or more as an improvement rate (Nu / Nuplate) as compared with a plate using flat fins. As a result, the heat exchange efficiency of the heat exchanger can be improved.

  In the fin tube heat exchanger 20 of the embodiment, the peak portion 34 and the valley portion from the portion (center portion) where the air passage of the fin 30 is formed toward the inflow portion forming portion 37 and the outflow portion forming portion 38 at the end. The fins 30 are formed so that the amplitude of the waveform due to 36 gradually decreases, and the inflow portion forming portion 37 and the outflow portion forming portion 38 are formed to be flat surfaces, but the air passage of the fin is formed. The amplitude of the waveform due to the peaks and troughs does not change from the part (center) to the inflow part formation part or outflow part formation part at the end, and the waveform is in the vicinity of the inflow part formation part or the outflow part formation part. Each of the fins may be formed so that the inflow portion forming portion and the outflow portion forming portion are flat.

  In the fin tube heat exchanger 20 of the embodiment, the fins 30 are formed so that both the inflow portion forming portion 37 and the outflow portion forming portion 38 of the fin 30 are flat surfaces. Only one of the part formation sites 38 may be a flat surface and the other may not be a flat surface. Further, the inflow portion forming portion 37 and the outflow portion forming portion 38 may be formed in a waveform as long as the amplitude is smaller than the amplitude of the waveform of the portion (center portion) where the air passage of the fin 30 is formed. .

  In the fin tube heat exchanger 20 of the embodiment, each fin 30 is formed so that the inflow portion forming portion 37 and the outflow portion forming portion 38 of the fin 30 are flat surfaces. As shown in the tube heat exchanger 20C and the fins 30C, reinforcing ribs 40C and 41C that reinforce the strength along the inflow portion and outflow portion of air are formed in the vicinity of the inflow portion formation portion 37C and the outflow portion formation portion 38C. It is good also as what to do. Here, FIG. 11 shows a DD cross section of the finned tube heat exchanger 20C of the modification of FIG. If it carries out like this, the intensity | strength of the fin 30C can be increased and it can suppress that the fin 30 bends, when laminating | stacking. As a result, the assembling property of the heat exchanger can be improved. In the fin tube heat exchanger 20C of the modified example, the reinforcing ribs 40C and 41C are formed in the vicinity of the inflow portion forming portion 37C and the outflow portion forming portion 38C of the fin 30C. Reinforcing ribs may be formed only in the vicinity of one of the portion forming portion 37C and the outflow portion forming portion 38C.

  In the fin tube heat exchanger 20 of the embodiment, as shown in FIG. 1, the crest 34 and the trough 36 in the fin 30 are bent three times between adjacent heat transfer tubes. The part 36 may be bent any number of times. Further, in the fin tube heat exchanger 20 of the embodiment, the peak portion 34 and the valley portion 36 of the fin 30 are bent so as to be symmetrical at the center between adjacent heat transfer tubes. 36 may not be bent. In this case, it is not symmetrical at the center between adjacent heat transfer tubes.

  In the finned tube heat exchanger 20 of the embodiment, on the air outflow side, the crests 34 and the troughs 36 of the fins 30 are provided so that air flows in the dead water area behind the heat transfer tubes 22a to 22c in the air flow direction. Although formed, it is good also as what does not form the peak part 34 and trough part 36 of each fin 30 so that air may flow into the dead water area of the flow direction back of each heat exchanger tube 22a-22c in this way. . In this case, similarly to the air inflow side, the crest 34 and the trough 36 may be formed in the fin 30 so that the angle γ formed with respect to the air stream line is a predetermined acute angle (30 degrees). .

  The best mode for carrying out the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention. Of course, it can be implemented in the form.

  The present invention can be used in the heat exchanger manufacturing industry and the like.

It is a block diagram which shows the outline of a structure of the finned-tube heat exchanger 20 as one Example of this invention. It is sectional drawing which shows the AA cross section of the finned-tube heat exchanger 20 in FIG. It is sectional drawing which shows CC cross section of the finned-tube heat exchanger 20 in FIG. It is a perspective view of CC vicinity of the fin 30 of the fin tube heat exchanger 20 in FIG. It is explanatory drawing explaining the streamline of air when the fin tube heat exchanger 20B is comprised by the fin 30B formed as a mere flat plate. It is sectional drawing which shows a cross section when the fin 30 is fractured | ruptured along curve B1-B2 in FIG. 1 which connects the bending part of the peak part 34 and the trough part 36. FIG. It is explanatory drawing which shows the secondary flow of the air produced on a flat plate, and the contour line by temperature when air of the uniform flow with a small flow velocity is introduce | transduced into a corrugated flat plate. It is explanatory drawing which shows an example of the calculation result which investigated the relationship between an amplitude pitch ratio (a / p) and the improvement rate (h / hplate) of a heat transfer rate. It is explanatory drawing which shows an example of the calculation result which investigated the relationship between the inclination-angle (alpha) and the Nusselt number improvement rate (Nu / Nuplate). It is a block diagram which shows the outline of a structure of 20 C of fin tube heat exchangers of a modification. It is sectional drawing which shows the DD cross section of 20 C of fin tube heat exchangers in FIG.

Explanation of symbols

  20, 20B, 20C Finned tube heat exchanger, 22a-22c Heat transfer tube, 30, 30B, 30C Fin, 32a-32c Mounting part, 34 Mountain part, 36 Valley part, 37, 37C Inflow part forming part, 38, 38C Outflow Part formation site, 40C, 41C rib.

Claims (4)

A heat exchanger for exchanging heat between air and a heat exchange medium,
A plurality of heat transfer tubes arranged in parallel as flow paths of the heat exchange medium;
An air inflow portion for inflowing air, an air outflow portion for outflowing air, and an air passage extending from the air inflow portion to the air outflow portion intersecting the plurality of heat transfer tubes so as to be capable of exchanging heat are arranged in parallel. A plurality of corrugated fin members stacked on each other;
With
The plurality of fin members are arranged such that at least an angle between a main flow of the air flow on the air inflow side and the wave is an angle within a range of 10 degrees to 60 degrees, and a top portion connecting the top portions of the waves. A wave is formed so that the line is bent a plurality of times, and a wave is formed so that a bending line connecting the bending points of the top lines of adjacent waves on the inflow side coincides with the mainstream, Furthermore, the heat exchanger is characterized in that the wave amplitude in the vicinity of the portion forming the air inflow portion and / or the air outflow portion is smaller than the amplitude of the wave in the portion forming the passage. .   2. The heat exchanger according to claim 1, wherein the plurality of fin members are formed to have a flat surface in a portion where the air inflow portion and / or the air outflow portion are formed.   3. The heat exchanger according to claim 1, wherein the plurality of fin members are formed with reinforcing ribs in the vicinity of portions that form the air inflow portion and / or the air outflow portion. The heat exchanger according to any one of claims 1 to 3, wherein the plurality of fin members are formed with waves so that air flows in a dead water area behind the heat transfer tube in the air flow direction.

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