JP5185611B2 - Fin and tube heat exchanger - Google Patents

Description

  The present invention relates to a heat exchanger for exchanging heat between a fluid (refrigerant) flowing in a heat transfer tube and an air flow (air) flowing between a large number of plate fins provided outside thereof, and in particular, air conditioning. The present invention relates to a fin-and-tube heat exchanger suitable for use in an air heat exchanger of a refrigerator or refrigerator.

In fin-and-tube heat exchangers used in air heat exchangers such as air conditioners and refrigerators, the fin side (air side) is improved by applying various devices to the fin side and increasing its heat transfer area. The heat transfer rate is improved to improve performance. On the other hand, in order to reduce the input to the blower fan that circulates air through the heat exchanger and to save energy, it is desirable to reduce the fin-side flow resistance (air-side pressure loss) as much as possible. However, there is a conflict between reducing the fin-side flow resistance and improving the heat transfer coefficient.
Further, in the air heat exchanger, since the air flow path is blocked by frost formation on the fins and there is a concern about the reduction of the exchange heat amount, it is necessary to consider the suppression of frost formation when designing the fins. .

Under these circumstances, for each row of tube holes provided in the plate fins, a plurality of ridges are provided along the air flow direction, and a flat seat is formed around the tube holes, Patent Document 1 proposes a heat exchanger in which the lower end portion of the seat has an acute angle and the top portion matches the ridge line of the peak portion.
Further, for each row of tube holes provided in the plate fin, a plurality of triangular peaks or trapezoidal peaks with flat tops are provided along the air flow direction, and one peak of the peaks is provided. Patent Document 2 proposes a heat exchanger in which the height is made larger than the height of the adjacent peak portions and the peak portions are provided concentrically around the tube hole.

JP-A-8-178573 JP-A-10-141880

  The thing of the said patent document 1 leads the turbulent flow which destroys the temperature boundary layer of air in the fin whole area by a mountain part, and guides an airflow to the back of a heat exchanger tube by the wall part along the ridgeline of a seat, and is a dead water area By reducing the heat transfer rate, the heat transfer rate can be improved, while water droplets adhering to the fin surface can flow down and discharge as quickly as possible. However, the ridge configuration is a monotonous repeating configuration of ridges of the same shape along the row direction of the tube holes, so there is a limit in improving the heat transfer coefficient, and not only a sufficient effect cannot be expected, but also the ridgeline of the seat The wall along the wall serves to reduce the dead water area (ineffective heat transfer area), but on the other hand, it becomes a wall against the air flow in the area where the air flow velocity is high near the heat transfer tube, and there is a problem of increasing pressure loss due to the flow resistance. .

Moreover, since the thing of patent document 2 can meander the airflow which flows between plate fins by the height change of a mountain part, it can improve heat-transfer performance, suppressing the distribution resistance of airflow. In addition, since the concentric ridges provided around the tube hole can guide the air flow to the rear of the heat transfer tube, the dead water area can be reduced and the heat transfer performance can be improved. However, the peak portion is only one-way peak along the row direction of the tube holes, and a sufficient improvement in heat transfer coefficient due to the turbulent flow promotion effect cannot be expected. Further, an increase in fin-side flow resistance around the tube hole (increase in pressure loss) is unavoidable, and there is a concern about an increase in input to the blower fan.
Thus, the conventional fin-and-tube heat exchanger still has room for improvement with respect to the heat transfer coefficient and flow resistance (pressure loss) on the fin side.

  The present invention has been made in view of such circumstances, and has been improved in performance by further improving the fin-side heat transfer coefficient without increasing the air-side flow resistance (pressure loss). Another object of the present invention is to provide a fin-and-tube heat exchanger.

In order to solve the above problems, the fin-and-tube heat exchanger of the present invention employs the following means.
That is, a number of fin-and-tube heat exchangers according to the present invention are arranged in parallel at a predetermined pitch, plate fins through which airflow flows, and provided at predetermined row pitches and step pitches between the plate fins. A fin-and-tube heat exchanger having a heat transfer tube that is inserted in close contact with the tube hole and through which a fluid is circulated, wherein the plate fin has a row with respect to the row of the tube holes. At least three or more column-direction ridges are provided along the direction, and the step-direction ridges along the step direction are provided between the tube holes adjacent in the step direction. A three-dimensional mountain portion projecting in both the row direction and the step direction is formed, and a flat portion is formed on the top portion .

According to the present invention, the row of tube holes of the plate fin is provided with at least three or more row ridges along the row direction, and between the tube holes adjacent in the row direction, the step along the row direction. By providing the direction peak portion, the step-direction peak portion is a three-dimensional peak portion protruding in both the row direction and the step direction, and a flat portion is formed at the top portion thereof. Sufficient turbulent flow can be generated to destroy the temperature boundary layer with respect to the airflow flowing between the plate fins by the synergistic effect of promoting turbulent flow between the directional ridge and the step ridge. For this reason, a heat transfer rate can be raised further. In addition, the airflow flowing between the plate fins smoothly flows immediately after the heat transfer tube by the downward slope toward the tube hole of the stepwise mountain portion protruding in the three-dimensional direction. Further, the region having a high local air-side heat transfer coefficient can be increased by the flat portion at the top of the stepwise mountain portion. For this reason, without increasing the flow resistance (pressure loss) on the airflow side, the dead water area of the plate fin can be reduced to increase the effective heat transfer area, the heat transfer rate can be improved, and the local air side heat transfer The area with a high rate can be increased and the average heat transfer rate can be improved. Therefore, the heat transfer rate improvement effect commensurate with the increase in effective heat transfer area can be obtained, and the heat transfer performance can be improved. In addition, this makes it possible to secure the amount of heat for exchange while widening the fin pitch, so that the number of fins can be reduced and the cost can be reduced.

  Furthermore, the fin-and-tube heat exchanger of the present invention is the above-described fin-and-tube heat exchanger, wherein the row ridges are formed at the height of both ridges formed at both ends in the row direction. It is characterized by being lower than the height of the central mountain.

  According to the present invention, the heights of both end ridges formed at both ends in the column direction of the row ridges are lower than the height of the central ridge formed therebetween, On the other hand, air currents alternately collide and peel off repeatedly. In general, the heat transfer coefficient is high on the collision surface and the heat transfer coefficient is low on the peeling surface. Therefore, the heat transfer coefficient can be improved as an average value by increasing the region having a high heat transfer coefficient. At this time, the local heat transfer coefficient at the peak is averaged to be a constant high value by lowering the height of the peak at both ends, which originally has a high heat transfer coefficient, and increasing the height of the central peak than that. be able to. Therefore, the heat transfer performance can be improved to a certain high value without increasing the flow resistance (pressure loss) on the airflow side. Further, by lowering the peak portion on the rear end side in the airflow distribution direction in the plate fin, the airflow can be made to flow around the heat transfer tube downstream side, and heat exchange there is promoted. For this reason, the heat transfer coefficient at the air flow outlet side of the wake of the heat transfer tube is recovered, and the heat transfer performance can be improved by this. Furthermore, since the crest of the air passage due to fin frosting can be suppressed by keeping the peak portion on the front end side in the air flow direction in the plate fin, it is possible to suppress the decrease in the air flow rate and the decrease in the exchange heat amount. it can.

  Furthermore, the fin-and-tube heat exchanger according to the present invention is the above-described fin-and-tube heat exchanger, wherein the row-direction ridges are formed in four ridges, and both-end ridges are formed at both ends in the row direction. It is characterized in that the height of the two central mountain portions formed therebetween is higher than the height of the portion.

  According to the present invention, four ridges in the row direction along the row direction are formed, and these ridges in the row direction are two centers formed between the heights of the ridge portions at both ends in the row direction. Since the height of the ridges is increased, it can bring about the effect of promoting turbulence by each ridge and the improvement of local heat transfer coefficient by increasing the collision surface, and at the same time, the resistance balance against the airflow in the row direction is improved. can do. For this reason, not only the airflow flows in the central region between the tube holes, but also a lot of flow is formed along the periphery of the heat transfer tube. Therefore, the effective heat transfer area in the region immediately after the heat transfer tube can be increased, and the effect of improving the heat transfer rate can be further increased.

  Furthermore, the fin-and-tube heat exchanger of the present invention is the fin-and-tube heat exchanger according to any one of the above, wherein the flat portion has a ratio of the length in the step direction to the step pitch of 1/3 or less. It is characterized by being.

  According to the present invention, since the ratio of the length in the step direction to the step pitch of the flat portion is 1/3 or less, the local air-side heat transfer coefficient is increased without increasing the flow resistance (pressure loss) on the airflow side. The high region can be increased, and a high heat transfer rate can be ensured. If the length of the flat part is too long, the pressure loss in the region where the air flow velocity around the heat transfer tube is high tends to increase. However, by setting the ratio of the length to the step pitch to 1/3 or less, high heat The transmission rate can be maintained.

  Furthermore, the fin-and-tube heat exchanger of the present invention is the above-described fin-and-tube heat exchanger, wherein the flat portion has a ratio of the length in the step direction to the pitch between the heat transfer tubes of 0. It is characterized by being 5 or less.

  According to the present invention, since the ratio of the length in the step direction with respect to the pitch between the heat transfer tubes of the flat portion is 0.5 or less, the local air side is increased without increasing the flow resistance (pressure loss) on the air flow side. A region having a high heat transfer rate can be increased, and a high heat transfer rate can be secured. If the length of the flat part is too long, the pressure loss in the region where the air flow velocity near the heat transfer tube is high tends to increase, but the ratio of the length to the pitch between the heat transfer tubes is 0.5 or less. High heat transfer rate can be maintained.

According to the present invention, it is possible to generate a sufficient turbulent flow to destroy the temperature boundary layer for the airflow flowing between the plate fins by the synergistic effect of the turbulent flow promotion between the row ridge and the step ridge. Therefore, the heat transfer rate can be further increased. In addition, the airflow flowing between the plate fins smoothly flows immediately after the heat transfer tube by the downward slope toward the tube hole of the stepwise mountain portion protruding in the three-dimensional direction. Further, the region having a high local air-side heat transfer coefficient can be increased by the flat portion at the top of the stepwise mountain portion. For this reason, without increasing the flow resistance (pressure loss) on the airflow side, the dead water area of the plate fin can be reduced to increase the effective heat transfer area, the heat transfer rate can be improved, and the local air side heat transfer The area with a high rate can be increased and the average heat transfer rate can be improved. Therefore, the heat transfer rate improvement effect commensurate with the increase in effective heat transfer area can be obtained, and the heat transfer performance can be improved. In addition, this makes it possible to secure the amount of heat for exchange while widening the fin pitch, so that the number of fins can be reduced and the cost can be reduced.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view of a fin-and-tube heat exchanger 1 according to the present embodiment. A large number of fin-and-tube heat exchangers 1 are arranged in parallel at a predetermined pitch, and plate fins 2 through which airflow (air) flows are provided, and these plate fins 2 are provided at a predetermined row pitch and step pitch. A heat transfer tube 4 that is inserted in close contact with the tube hole 3 and through which a fluid (refrigerant) flows. The heat transfer tube 4 is composed of a large number of hairpin tubes 4A inserted in close contact with the tube holes 3 of the plate fins 2, and U-bends 4B that connect ends of adjacent tubes of the hairpin tubes 4A. In the core portion of the heat exchanger 1, a refrigerant flow path having at least one pass is formed. In general, a copper tube is used as the heat transfer tube 4.

  FIG. 2 shows a side view of the plate fin 2. The plate fin 2 is generally manufactured by punching an aluminum thin plate (for example, a thickness of 0.1 mm) into a rectangular shape by pressing. As shown in FIG. 2, the plate fin 2 has a rectangular shape with a width dimension of M and a vertical dimension of N. In this embodiment, the plate fin 2 has a predetermined row pitch m (for example, 18 mm) in the width direction. The holes 3 are provided in 1 to 2 rows (2 rows in the figure). In addition, the dimension from the plate fin right-and-left end surface of the tube hole 3 of the width direction both sides is 1 / 2m (m is row pitch). Further, in the vertical direction, the tube holes 3 are appropriately provided at a predetermined step pitch n (for example, 21 mm) between the dimensions N1. In addition, the dimension from the upper end and lower end of the plate fin of the tube hole 3 located in the uppermost stage and the lowermost stage of each row is set to 3 / 4n (n is a step pitch) or 1 / 4n, respectively. As a result, the tube holes 3 in adjacent rows are arranged in a staggered manner.

  FIG. 3 shows one piece of the plate fin 2 divided into four equal parts in the row direction and the step direction around the tube hole 3, and FIG. 4 shows a cross-sectional view corresponding to the AA cross section in FIG. FIG. 2 shows a cross-sectional view corresponding to the line BB in FIG. The tube hole 3 is provided with a collar 3A around the hole by burring. The hole diameter Φ of the tube hole 3 is made slightly larger than the diameter of the heat transfer tube 4 that has been reduced in diameter (for example, 6.35 mm). 3A and the heat transfer tube 4 are brought into close contact with each other. The collar 3 </ b> A has a height of, for example, 1.2 mm, and the fin pitch Pf of the plate fins 2 disposed in a stacked manner is determined by the height of the collar 3 </ b> A.

  As shown in FIG. 4, the plate fin 2 has at least three (in this embodiment, four cases) along the row direction (width direction) for each row of tube holes 3. In FIG. 4, two of them are shown). The plurality of column-direction peaks 5 are center peaks provided at the center in the column direction rather than the height h1 (for example, 0.4 mm) of the two both-end peaks 5A, 5D provided at both ends in the column direction. The height h2 (for example, 0.7 mm) of the parts 5B and 5C is made higher.

  The width in the row direction of these row direction ridges 5 is such that the width direction dimension p from the lowest height position to the highest height position of both ridges 5A, 5D is, for example, 1.4 mm, while A width direction dimension q from the lowest height position to the highest height position of the portions 5B and 5C is, for example, 2.8 mm. Thereby, the gradient of each mountain of the row direction mountain part 5 is made substantially the same. Further, flat portions 5E and 5F having a width dimension r are provided at both ends of the plate fin 2 in the width direction. In addition, it is assumed that an appropriately sized arc is provided at the top and valley of each peak 5A to 5D.

  Further, as shown in FIG. 5, the plate fin 2 has two stepwise peaks along the stepwise direction corresponding to the central peaks 5B and 5C in the column direction between the tube holes 3 adjacent to each other in the stepwise direction. 6 is provided. The height of the stepwise ridge 6 is the same as the height h1 (for example, 0.4 mm) of the ridges 5A and 5D at both ends in the column direction, and a flat portion (flat portion) is formed at the top. 7 is formed. The length F of the flat portion 7 (1 / 2F is shown in FIG. 5) is 1/3 or less of the step pitch n, or the inter-tube pitch Pt of the heat transfer tubes 4 (FIG. 2). It is 0.5 or less with respect to the reference) and is generally set in the range of 2 to 6 mm.

In this way, by providing the stepwise mountain portion 6 with the flat portion 7 formed at the top between the tube holes 3 adjacent to each other in the step direction, between the tube holes 3 adjacent to each other in the row direction, A three-dimensional mountain portion projecting in both the step directions (three-dimensional direction) is formed.
In the present embodiment, since the two central mountain portions 5B and 5C in the row direction are arranged between the tube holes 3 adjacent in the step direction, two stepwise mountain portions 6 are also provided corresponding thereto. However, when there is one central peak portion in the column direction (in the case of three column direction peak portions 5), one stepwise peak portion 6 is also provided correspondingly.

With the configuration described above, according to the present embodiment, the following operational effects are obtained.
Air is blown to the fin-and-tube heat exchanger 1 along the width direction of the plate fins 2 as shown by an arrow I in FIG. When this air flows between the plate fins 2, heat exchange is performed with the refrigerant flowing in the heat transfer tubes 4. The air flowing between the plate fins 2 is first guided to the flat portion 5E having the width dimension r provided at the front end in the width direction and flows between the plate fins 2 without resistance. Then, in the process of flowing between the plate fins 2, the turbulent flow is guided by the row direction ridges 5 and the step direction ridges 6, and turbulent enough to repeatedly collide and peel off the ridges and destroy the temperature boundary layer. While generating or changing the direction to the flow area immediately after the heat transfer tube 4 mainly by the action of the stepped ridges 6, the fluid flows between the plate fins 2 and flows out from the rear end.

  In this embodiment, as shown in FIGS. 2 to 5, four row direction ridges 5 are provided in the row direction of the plate fins 2, and the heights of both end ridges 5 </ b> A and 5 </ b> D are reduced, Since the heights of the portions 5B and 5C are made higher than the heights of both end ridges 5A and 5D, and further, the stepwise ridges 6 are provided in the stepwise direction corresponding to the central ridges 5B and 5C. By the action of the parts 5 and 6, the local heat transfer coefficient in the air inflow part can be set to a substantially constant high value on average.

  That is, in the type of plate fin 2 having a plurality of row-direction peaks 5 in the row direction, the heat transfer coefficient at the collision surface is high and the heat transfer coefficient at the separation surface is low. By increasing the area having a high heat transfer coefficient, the heat transfer coefficient can be improved as an average value. Moreover, since the heat transfer area can be increased by the mountain portion 5, the heat transfer performance can be improved also by this. If only the heat transfer coefficient improvement on the fin side is considered, all the heights of the ridges 5 in the row direction need only be increased. However, this increases the flow resistance on the fin side (increases the air side pressure loss), and the blower fan. Since the input to is increased, it is not preferable for energy saving. Therefore, as described above, by reducing the height of the both end ridges 5A, 5D on the fin end surface side and increasing the height of the central ridges 5B, 5C from that height, without increasing the flow resistance, The local heat transfer coefficient can be averaged to a high value.

  Moreover, since the peak portion 5D on the rear end side of the plate fin 2 is lowered, the heat transfer coefficient in the airflow outlet region behind the heat transfer tube 4 fitted in the tube hole 3 can be recovered. This is thought to be because by lowering the peak portion 5D on the fin rear end side, an air flow that wraps around the wake region of the heat transfer tube 4 is formed, and heat exchange between the fin and the air flow is promoted there. It is done. Further, in the row direction crest 5 of the plate fin 2, the width direction dimension q along the row direction of the central crests 5B and 5C is larger (twice) than the width direction dimension p of both end crests 5A and 5D. Therefore, the slopes of these peaks 5A to 5D can be made substantially the same. This suppresses an increase in the flow resistance (airflow side pressure loss) with respect to the air flow and reduces the input to the blower fan, while increasing the height of the row direction ridges 5 and local heat transfer in the row direction ridges 5. The rate can be further increased.

  Another reason for lowering the peak portion 5A on the front end side of the plate fin 2 is to suppress frost formation on the fin. For example, when this fin-and-tube heat exchanger 1 is used for an outdoor heat exchanger of an air conditioner, frost is generally easily frosted at the front end edge of the plate fin 2 having a high heat transfer rate during heating operation. . If the height of the front end crest portion 5A of the plate fin 2 is increased, the fin gap becomes smaller, the air flow passage is blocked by frost formation, or the air volume decreases as the flow path resistance increases due to frost formation. In addition, the reduction of the exchange heat amount becomes faster, and frost formation becomes easier. However, by lowering the height of the peak portion 5A at the front end of the plate fin 2, frost formation on the fin can be suppressed and these problems can be solved.

  On the other hand, since the plate fin 2 is provided with a stepwise ridge 6 along the stepwise direction between the tube holes 3 adjacent to each other in the stepwise direction, heat transfer is also caused by the effect of promoting turbulence by the stepwise ridge 6. The rate can be improved. Moreover, since the downward hill (inclined surface) which goes to the tube hole 3 direction can be formed between the tube holes 3 adjacent to a step direction by the step direction peak part 6, it distribute | circulates between the plate fins 2 along this slope. It is possible to cause the air flow to flow around to the rear of the heat transfer tube 4 fitted in the tube hole 3. As a result, the dead water area (ineffective heat transfer area) behind the heat transfer tubes 4 (tube holes 3) of the plate fins 2 can be reduced and the effective heat transfer area of the fins can be increased. Can be improved.

  In particular, four row direction mountain portions 5 are provided, and the step direction mountain portions 6 are provided so as to correspond to the two central mountain portions 5B and 5C whose heights are increased. As a result, a three-dimensional mountain portion projecting in both the row direction and the step direction (three-dimensional direction) is formed between the tube holes 3 adjacent to each other in the step direction, and the resistance balance against the air flow is improved. can do. For this reason, not only the air flow flows through the central region between the heat transfer tubes 4 adjacent to each other in the plate fin 2 step direction, but also a sufficient air flow is formed along the periphery of the heat transfer tubes 4. . Therefore, the effective heat transfer area in the flow area immediately after the heat transfer tube 4 can be further increased, and the heat transfer rate can be further improved.

  Furthermore, in this embodiment, since the flat part (flat part) 7 is formed in the top part of the step direction peak part 6, it can increase an area with a high local air side heat transfer rate by this flat part 7, As a result, the average heat transfer coefficient can be improved. The flat portion 7 has a length F in the step direction of 1/3 or less with respect to the step pitch n, or 0.5 or less with respect to the inter-tube pitch Pt of the heat transfer tubes 4, and is generally in the range of 2 to 6 mm. Therefore, as shown in FIG. 6, the air-side heat transfer coefficient αa can be further increased by several% in proportion to the case where the flat length F is zero. If the length F of the flat portion 7 is longer than the above, the pressure loss in the region where the air flow velocity around the heat transfer tube 4 is high tends to increase, so that the air-side flow resistance (pressure loss) is suppressed, The above can be said to be an appropriate range for improving the heat transfer performance.

  As described above, according to the present embodiment, the turbulence sufficient to destroy the temperature boundary layer of the airflow is obtained by the synergistic effect of the row-direction ridges 5 and the step-direction ridges 6 provided in the plate fins 2. Since the flow can be generated, the heat transfer rate can be improved. In addition, four row ridges 5 are formed, the heights of the ridges 5A and 5D at both ends are lowered, and the heights of the two central ridges 5B and 5C formed therebetween are increased to transfer heat. By increasing the collision area of the air flow with a high rate, the local heat transfer coefficient of the ridges 5 in the row direction can be averaged to a constant high value, thus improving the heat transfer performance to a constant high value. Can be made.

  In addition, since the peak portion 5D on the rear end side of the row direction peak portion 5 is lowered, and this peak portion 5D forms an air flow that wraps around the wake region of the heat transfer tube 4, the fins there Heat exchange with the air flow can be promoted, and the heat transfer coefficient in the wake region of the heat transfer tube 4 can be improved. Moreover, since the peak portion 5A on the front end side of the row direction peak portion 5 is lowered and the fin gap at the fin front end having a high heat transfer coefficient is increased, frost formation on the fins can be suppressed.

  Furthermore, the width of the low-end ridges 5A, 5D of the row direction ridges 5 is reduced, and the widths of the two central ridges 5B, 5C formed between them are increased, and the gradient is increased. Therefore, while increasing the flow resistance (air flow side pressure loss) against the air flow and reducing the input to the blower fan, the height of the row direction mountain portion 5 is increased, and the row direction mountain is increased. The local heat transfer coefficient of the part 5 can be averaged to a constant high value. Further, the flat fins 5E and 5F are provided at both ends in the width direction of the plate fin 2 to guide the inflow of air and reduce the inflow resistance (pressure loss on the airflow side). Reduction and energy saving can be achieved.

  Further, the plate fins 2 are circulated by the downward inclined surfaces facing the tube holes 3 of the three-dimensional mountain portion provided so as to protrude in both the row direction and the step direction between the tube holes 3 adjacent in the step direction. Since the air flow can be made to flow immediately after the heat transfer tube 4 and the dead water area of the plate fin 2 can be reduced to increase the effective heat transfer area, the heat transfer performance can be improved accordingly. In particular, by providing two stepwise ridges 6 corresponding to the two central ridges 5B and 5C of the rowwise ridges 5 and forming ridges protruding in a three-dimensional direction, Immediately after the heat transfer tube 4, the resistance balance is improved and a sufficient air flow can be formed not only in the central region between the heat transfer tubes 4 adjacent in the step direction but also around the heat transfer tube 4. The effective heat transfer area in the basin can be further increased and the heat transfer rate can be further improved.

  Furthermore, since the area | region with a high local air side heat transfer coefficient is increased by forming the flat part (flat part) 7 in the top part of the step direction peak part 6, an average heat transfer coefficient can be improved. At this time, the length F of the flat portion 7 in the step direction is 1/3 or less with respect to the step pitch n, or 0.4 or less with respect to the inter-tube pitch Pt of the heat transfer tube 4, and is approximately in the range of 2 to 6 mm. Since it is set, the air-side heat transfer coefficient αa can be further increased by several percent at a ratio to the case where the flat length F is 0 while suppressing the flow resistance (pressure loss) on the air side, and the heat transfer performance is improved. Can be improved. Further, by improving the heat transfer rate by improving the fin structure and enhancing the heat transfer performance, it becomes possible to secure the exchange heat amount while widening the fin pitch, and therefore the number of plate fins 2 can be reduced. In addition, the material cost can be reduced even when the diameter of the heat transfer tube 4 is reduced (for example, the tube diameter Φ is 6.35 mm). Therefore, cost reduction can be realized.

  In addition, this invention is not limited to the invention concerning the said embodiment, In the range which does not deviate from the summary, it can change suitably. For example, in the said embodiment, although the dimension of each part of a plate fin is shown with the specific numerical value, this is only an example to the last, and this invention is not limited to this. Of course, the number of rows and the number of stages of the tube holes 3 are appropriately changed according to the ability of the heat exchanger.

It is a perspective view of the fin and tube type heat exchanger concerning one embodiment of the present invention. It is a side view of the plate fin of the fin and tube type heat exchanger shown in FIG. FIG. 3 is a perspective view of a piece that is divided into four equal parts in a row direction and a step direction around a tube hole of a plate fin shown in FIG. 2. FIG. 4 is a cross-sectional view corresponding to the AA cross section of FIG. 2 of one piece of the plate fin shown in FIG. 3. FIG. 4 is a cross-sectional view corresponding to the BB cross section of FIG. 2 of one piece of the plate fin shown in FIG. 3. It is a relationship graph of the flat part length F of the step direction peak part of the plate fin shown in FIG. 2, and the air side heat transfer coefficient (alpha) ratio.

DESCRIPTION OF SYMBOLS 1 Fin and tube type heat exchanger 2 Plate fin 3 Tube hole 4 Heat-transfer tube 5 Row direction peak part 5A, 5D Both-ends peak part 5B, 5C Center peak part 6 Step direction peak part 7 Flat part (flat part)
F Flat length m Row pitch n Step pitch Pt Tube pitch

Claims (5)

A large number of parallel plates are arranged at a predetermined pitch, and are inserted in close contact with plate fins through which airflow flows, and tube holes provided at a predetermined row pitch and step pitch in the plate fins, and fluid flows through the inside. A fin-and-tube heat exchanger comprising:
The plate fin is provided with at least three or more row ridges along the row direction with respect to the row of tube holes, and the step direction along the step direction between the tube holes adjacent in the step direction. By providing a peak, the stepwise peak is a three-dimensional peak protruding in both the row direction and the stepwise direction, and a flat portion is formed at the top. Fin-and-tube heat exchanger. 2. The fin according to claim 1 , wherein in the row-direction ridges, the heights of both-end ridge portions formed at both ends in the row direction are lower than the height of the central ridge portion formed therebetween. And tube type heat exchanger. The row ridges are formed as four ridges, and the heights of the two central ridges formed therebetween are higher than the heights of both ridges formed at both ends in the row direction. The fin-and-tube heat exchanger according to claim 1 or 2 . The fin-and-tube heat exchanger according to any one of claims 1 to 3 , wherein the flat portion has a ratio of a length in a step direction to the step pitch of 1/3 or less. The flat portion, the ratio of the step length in the direction to the pitch between the heat transfer tubes, fin and tube type heat exchanger according to any one of claims 1 to 4, characterized in that it is 0.5 or less vessel.

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