JP2008128569A - Fin and tube type heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fin and tube type heat exchanger, further improving the fin side heat transfer coefficient and reducing the circulation resistance on the air side to achieve high performance. <P>SOLUTION: This fin and tube type heat exchanger 1 includes: a number of plate fins 2 disposed in parallel at a predetermined pitch to circulate an air current therebetween; and a heat transfer tube 4 closely inserted in tube holes 3 provided at predetermined column pitch and step pitch in the plate fins 2 to circulate a fluid through the interior thereof, wherein the plate fins 2 are provided with a first crest part 6 provided along the step direction between the tube holes 3 adjacent to each other in the step direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

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 for air conditioners and refrigerator air heat exchangers, heat is transferred on the fin side (air side) by making various improvements on the fin side and increasing its heat transfer area. The rate is improved to improve performance. On the other hand, it is desirable to reduce the fin-side flow resistance (air-side pressure loss) as much as possible in order to reduce input to the blower fan that circulates air through the heat exchanger and save energy. 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, Patent Document 1 proposes a wave finned portion provided at the front edge portion of the plate fin and a dimple provided in the heat transfer tube downstream portion (fin rear edge portion) of the fin. Yes.
Further, Patent Document 2 proposes a structure in which three peaks are provided along the air flow direction for each row of tube holes provided in the plate fin.
In addition, for each row of tube holes provided in the plate fin, a plurality of peaks are provided along the air flow direction, and peaks are provided concentrically around the tube holes. Proposed by reference 3.

JP 7-63490 A JP-A-9-79695 Japanese Patent No. 2661356

However, in the thing of patent document 1, since the wavy forming part and the dimple are provided only at the front edge part and the rear edge part of the plate fin, the partial heat transfer coefficient is improved at the front edge part and the rear edge part. The effect is only expected. Therefore, in such a configuration, in order to improve performance, it is necessary to take measures such as increasing the heat transfer area by closing the fin pitch.
Moreover, since the thing of patent document 2 has provided the peak part in the whole plate fin, it can produce the turbulent flow which destroys the temperature boundary layer of air in the whole fin area, and can improve a heat transfer rate, The air flow resistance does not become excessive, and the heat transfer performance of the entire heat exchanger is expected to be improved. However, structurally, only a limited and limited heat transfer coefficient improvement effect can be expected due to the monotonous repetitive configuration of the same shape peak portion. Moreover, the wake area of the heat transfer tube is a so-called dead water area (ineffective heat transfer area), and there is still room for improvement in this respect.

Moreover, the thing of patent document 3 can acquire the heat-transfer rate improvement effect equivalent to the thing of patent document 2 by the peak part provided in the row direction. In addition, since the air flow can be guided to the wake area of the heat transfer tube by the concentric peaks provided around the tube hole, the dead water area can be reduced and the heat transfer performance can be improved. However, on the other hand, it is unavoidable that the fin-side flow resistance around the tube hole increases (increase in pressure loss), and there is a concern about an increase in input to the blower fan.
As described above, the conventional fin-and-tube heat exchanger still has problems to be improved regarding 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 further improves the performance by further improving the fin-side heat transfer coefficient and reducing the air-side flow resistance (pressure loss). An 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, the fin-and-tube heat exchanger according to the present invention is provided in a large number in parallel at a predetermined pitch, plate fins through which airflow flows, and a predetermined row pitch and step pitch on the plate fins. A fin-and-tube heat exchanger having a heat transfer tube inserted in close contact with the tube hole and through which a fluid flows, wherein the plate fin has a step between the tube holes adjacent in the step direction. A stepwise mountain portion along the direction is provided.

  According to the present invention, since the step ridges along the step direction are provided between the tube holes adjacent to the plate fin in the step direction, the heat transfer coefficient can be improved by the effect of promoting turbulence by the step ridges. In addition, the airflow flowing between the plate fins can be caused to circulate immediately after the heat transfer tube by the downward inclined surface toward the tube hole in the stepped mountain portion. Thereby, the ineffective heat transfer area | region of a plate fin, what is called a dead water area, can be decreased, an effective heat transfer area can be increased, and a heat transfer rate can be improved by that. Therefore, the heat transfer performance can be improved without increasing the airflow resistance (airflow pressure loss).

  Also, the fin-and-tube heat exchanger according to the present invention is provided with a large number of parallel fins arranged at a predetermined pitch, and plate fins through which airflow is circulated, and are provided at predetermined row pitches and step pitches on the plate fins. A fin-and-tube heat exchanger having a heat transfer tube inserted in close contact with the tube hole and through which a fluid flows, wherein the plate fin has a row direction with respect to each row of the tube hole. There are at least three or more row-direction ridges along the row, and the row-direction ridges are lower than the height of the center ridge formed between the both-end ridges formed at both ends in the row direction. It is characterized by being.

According to the present invention, the plate fin is provided with at least three or more row-direction ridges along the row direction for each row of tube holes, and is formed at both ends of the row direction ridges in the row direction. The height of both end ridges is lower than the height of the central ridge formed between them, so that these row ridges can destroy the temperature boundary layer against the airflow flowing between the plate fins. Sufficient turbulence can be generated. Therefore, the heat transfer coefficient can be improved.
In addition, when the ridges are provided along the row direction of the tube holes, the air current repeatedly collides and peels at the ridges, the heat transfer coefficient is high on the collision surface, and the heat transfer coefficient is low on the peel surface. By increasing the region having a high heat transfer coefficient, the heat transfer coefficient can be improved as an average value. For this reason, the local heat transfer coefficient in the peak is averaged to 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. Thus, the heat transfer performance can be improved to a certain high value without increasing the flow resistance on the airflow side (airflow side pressure loss).
Moreover, since the peak portion on the rear end side in the airflow distribution direction in the plate fin is lowered, the airflow can also be circulated to the downstream side of the heat transfer tube, and heat exchange between the fin and the airflow is promoted there. The Accordingly, the heat transfer coefficient at the airflow outlet side of the heat transfer tube downstream is recovered, and the heat transfer performance can be improved by this.
Moreover, since the peak part of the airflow distribution direction front end side in a plate fin is made low, the frost formation with respect to a fin can be suppressed. In general, frost tends to form on the front end of the fin with a high heat transfer coefficient.If the height of the peak on the front end side of the fin is high, the gap between the plate fins becomes narrow, and the air flow rate increases as the resistance increases due to frost formation. descend. Thereby, the amount of exchange heat falls and it becomes easy to form frost further. Therefore, it is possible to suppress frost formation by lowering the peak portion on the front end side in the flow direction of the airflow.

  Furthermore, the fin-and-tube heat exchanger according to the present invention is the fin-and-tube heat exchanger described above, wherein the plate fin includes a gap between the tube holes adjacent to each other in the row direction along with the row direction mountain portions along the row direction. In addition, a step-wise peak portion is provided along the step direction, and a three-dimensional peak portion protruding in both the row direction and the step direction is provided between the tube holes adjacent in the step direction. To do.

  According to the present invention, between the tube holes adjacent to each other in the step direction, there is provided a three-dimensional peak portion protruding in both the column direction and the step direction. Due to the downwardly inclined surface facing the tube hole, the airflow flowing between the plate fins can be made to circulate immediately after the heat transfer tube. As a result, the ineffective heat transfer area of the plate fin, the so-called dead water area, can be reduced and the effective heat transfer area can be increased. Therefore, the heat transfer performance can be improved corresponding to the increase in the heat transfer area.

  Furthermore, the fin-and-tube heat exchanger of the present invention is the above-described fin-and-tube heat exchanger, wherein four column-direction peaks are formed at both ends in the column direction. It is characterized in that the height of the two central mountain portions formed between them is higher than the height of the mountain portions formed at both ends.

  According to the present invention, four ridges in the row direction along the row direction are formed, and the 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 high, it is possible to 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 good It can be. Thereby, 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 above-described fin-and-tube heat exchanger, in the row direction of the central mountain portion formed between the widths of the both-end mountain portions along the row direction. The width along the line is widened.

  According to the present invention, since the width along the column direction of the central mountain portion formed therebetween is wider than the width of the mountain peaks at both ends along the column direction, The gradient can be made substantially the same. This suppresses an increase in the flow resistance against the airflow (airflow side pressure loss) and reduces the input to the blower fan, while increasing the height of the peak and increasing the local heat transfer coefficient in the peak. Can do.

  Furthermore, the fin-and-tube heat exchanger according to the present invention is characterized in that, in any of the fin-and-tube heat exchangers described above, the plate fin is provided with a flat portion at least on an inflow side end surface thereof. And

  According to the present invention, since the plate fin is provided with a flat portion at least on the inflow side end surface of the airflow, the flat portion can guide the inflow of the airflow in the row direction, and the airflow inflow resistance (airflow Side pressure loss). Therefore, input to the blower fan can be reduced and energy saving can be achieved. Moreover, since this flat part can be utilized as a grip part at the time of manufacturing the press of a plate fin, manufacture of a fin can be facilitated.

  Furthermore, the fin-and-tube heat exchanger of the present invention is any one of the fin-and-tube heat exchangers described above, wherein each of the peak portions protrudes in one direction from the base surface of the plate fin. It is characterized by.

  According to the present invention, since each peak portion protrudes in one direction from the base surface of the plate fin, the manufacture of the plate fin can be facilitated. That is, this type of plate fin is usually manufactured by press molding, but since each peak portion projects in one direction from the base surface, the press surface may be formed in one direction of the base surface. Accordingly, it is possible to facilitate removal of the formed plate fins, conveyance of the fin material, and the like, and to improve fin productivity.

  According to the fin-and-tube heat exchanger of the present invention, not only can the heat transfer rate be improved by the turbulent flow promoting effect by the stepped ridges, but also by the downward inclined surface toward the tube hole of the stepped ridges. The airflow flowing between the plate fins can be made to circulate immediately after the heat transfer tube. For this reason, it is possible to increase the effective heat transfer area by reducing the ineffective heat transfer area of the plate fin, so-called dead water area, and to improve the heat transfer coefficient by the corresponding amount. Therefore, the heat transfer performance can be improved without increasing the fin side ventilation resistance (air side pressure loss).

  In addition, according to the fin and tube heat exchanger of the present invention, the ridges in the row direction can generate a sufficient turbulent flow that can destroy the temperature boundary layer for the airflow flowing between the plate fins. Accordingly, the heat transfer rate can be improved. Also, among the ridges in the row direction, the local heat transfer coefficient in the ridges is averaged by lowering the height of the ridges at both ends, which originally had a high heat transfer coefficient, and increasing the height of the central ridges. It can be a constant high value. For this reason, the heat transfer performance can be further improved without increasing the fin side ventilation resistance (air side pressure loss). Moreover, since the peak portion on the front end side in the air flow direction is lowered, a fin gap at the front end in the air flow direction can be secured to prevent a decrease in the air flow rate. Therefore, frost formation on the fins can be suppressed.

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 number of hairpin tubes 4A inserted in close contact with the tube holes 3 of the plate fins 2, and a U bend 4B that connects the 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 and forming a thin plate made of an aluminum alloy (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 tube fin 2 has a predetermined column pitch m (for example, 19 mm) in the width direction. Four rows of holes 3 are provided. In addition, the dimension from the plate fin right-and-left end surface of the tube hole 3 row | line | columns 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, 25 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 3 / 4n (n is a step pitch) or 1 / 4n. As a result, the tube holes 3 in adjacent rows are staggered with respect to each other.

  FIG. 3 is a cross-sectional view taken along the line AA in FIG. The tube hole 3 is provided with a collar 3A around the hole by burring. The tube hole 3 is formed to be slightly larger than the diameter of the heat transfer tube 4, and the collar 3 </ b> A and the heat transfer tube 4 are brought into close contact with each other by expanding the tube after the heat transfer tube 4 is inserted. Yes. The collar 3 </ b> A has a height h <b> 1 (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 h <b> 1.

  As shown in FIG. 3, 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. )) Is provided. The row direction peak portion 5 is a center peak portion 5B provided at the center portion in the row direction, rather than the height h2 (for example, 0.4 mm) of the two end peak portions 5A and 5D provided at both end portions in the row direction. , 5C height h3 (for example, 0.7 mm) is made higher.

Further, the width in the column direction of the column direction ridges 5 is such that the width direction dimension p from the lowest height position to the highest height position of both the mountain ridges 5A and 5D is 1.5 mm, for example. The width direction dimension q from the lowest height position to the highest height position of the peaks 5B and 5C is, for example, 3 mm. Accordingly, the slopes of the peaks in the row direction peak 5 are substantially the same.
Further, flat portions 5E and 5F having a width direction dimension r (for example, 0.5 mm) 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.

FIG. 4 shows a cross-sectional view taken along the line BB in FIG. As shown in FIG. 4, the plate fin 2 has two stepwise peaks along the stepwise direction corresponding to the central peaks 5B and 5C in the row direction between the tube holes 3 adjacent to each other in the stepwise direction. 6 is provided. The height of the stepwise peak 6 is the same as the height h3 (for example, 0.7 mm) of the central peaks 5B and 5C.
As described above, by providing the stepwise mountain portions 6 between the tube holes 3 adjacent to each other in the step direction, both the column direction and the step direction (three-dimensional direction) are provided between the tube holes 3 adjacent to each other in the step direction. A three-dimensional mountain portion projecting from is formed. In the present embodiment, since the two central mountain portions 5B and 5C in the column direction are arranged between the tube holes 3 adjacent in the step direction, two stepwise mountain portions 6 are also provided correspondingly. 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.

  Further, the plate fins 2 are stamped and formed from a roll material by pressing as described above. At the time of press forming, the collar 3A, the row direction peak portion 5 and the step direction peak portion 6 of the tube hole 3 are shown in FIG. The plate fin 2 shown is formed so as to protrude from the base surface 2A in one direction.

Below, an effect | action of the fin and tube type heat exchanger 1 concerning this embodiment is demonstrated.
Air is blown into 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, it flows between the plate fins 2 and flows out from the rear end.

Here, with reference to FIG. 5 thru | or FIG. 9, the outline of the heat flow analysis result of the said plate fin 2 is demonstrated.
FIG. 5 shows a part of the plate fin 2, and the arrow X indicates the air flow direction. The arrow direction orthogonal to the air flow direction X indicates the measurement position of the local heat transfer coefficient. FIG. 6 shows the local heat transfer coefficient [αa. On the front and back surfaces of the fin at the measurement position indicated by the arrows in FIG. 5 in the air flow direction X (mm). local (W / m ² K)] is shown, and FIG. 7 shows the local average heat transfer coefficient ratio [αa. The distribution of local / αam (−)] is shown. The fin pitch Pf is 1.2 mm as described above, and the front average wind speed Fv is 1.0 m / s. 5, 6 and 7 are shown in the opposite directions.
As shown in FIG. 3 and FIG. 4 described above, the plate fins 2 are provided with four ridges 5 in the column direction, the heights of the ridges 5A and 5D at both ends are lowered, and the heights of the central ridges 5B and 5C. Is higher than the heights of both end ridges 5A and 5D, and further, stepwise ridges 6 are provided corresponding to the central ridges 5B and 5C, so the local heat transfer coefficient in the air inflow portion is averaged. Thus, it can be set to a substantially constant high value.

As described above, in the plate fin 2 of the type provided with the row direction ridges 5, 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 with a high value, 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, if the flow resistance increases on the fin side (increase in air-side pressure loss), then the blower fan This increases the input to, which is against energy conservation.
Therefore, by reducing the height of both end ridges 5A, 5D on the fin end face side and making the height of the central ridges 5B, 5C higher than both end ridges 5A, 5D, without increasing the flow resistance, The local heat transfer coefficient can be averaged to a high value.

Further, as shown in FIGS. 6 and 7, the heat transfer coefficient can be recovered in the airflow outlet region behind the heat transfer tube 4 fitted in the tube hole 3 ′. This is because the crest 5D on the rear end side of the plate fin 2 is lowered, and this crest 5D forms an air flow that wraps around the wake area of the heat transfer tube 4, and the fin and air flow there This is thought to be because heat exchange with the plant is promoted.
Further, in the row direction peak portion 5 of the plate fin 2, the width direction dimension q along the row direction of the central peak portions 5B and 5C is larger (twice) than the width direction dimension p of the both end peak portions 5A and 5D. ), The slopes of the peak portions 5A, 5D and the central peak portions 5B, 5C 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 in the row direction ridges 5. The transmission rate can be set to a higher value.

  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 the fin-and-tube heat exchanger 1 is used as an outdoor heat exchanger of an air conditioner, frost is likely to be formed on the front end edge of the plate fin 2 having a high heat transfer rate during heating operation. Here, if the height of the front end crest portion 5A of the plate fin 2 is increased, the fin gap becomes smaller and the air flow path is blocked by frost formation, or the flow path resistance is increased by frost formation. Along with this, the air volume decreases, the decrease in the exchange heat amount becomes faster, and frost formation becomes easier. Therefore, 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.
In addition, since the stepped ridges 6 form a downward inclined surface in the direction of the tube hole 3 between the tube holes 3 adjacent to each other in the stepwise direction, the inclined surface allows the gap between the plate fins 2 to be formed. The flowing air flow can be made to flow into the flow area immediately after the heat transfer tube 4 fitted in the tube hole 3 ′.

  FIG. 8 shows a velocity vector distribution diagram at the fin upper surface position of 0.2 mm. Also from this velocity vector distribution diagram, it can be seen that a sufficient air flow is secured in the flow area immediately after the heat transfer tube 4 (tube hole 3).

As described above, as shown in FIG. 9, the ineffective heat transfer region (dead water region) 2S in the region immediately after the heat transfer tube 4 (tube hole 3) in the plate fin 2 can be reduced. Therefore, the effective heat transfer area of the fin can be increased, and the heat transfer rate can be improved accordingly.
In particular, in the present embodiment, four column-direction peaks 5 are provided, and two step-direction peaks 6 are provided so as to correspond to the two central peaks 5B and 5C having a higher height. . 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. It can be. 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 step direction of the plate fins 2, 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.

Further, flat portions 5E and 5F are provided at both ends in the width direction of the plate fin 2, and the inflow of airflow can be guided in the row direction by the flat portions 5E and 5F. Side pressure loss). Further, the flat portions 5E and 5F can be effectively used as a grip portion during plate fin press manufacturing.
Further, since the collar 3A, the row direction peak portion 5 and the step direction peak portion 6 of the tube hole 3 provided in the plate fin 2 protrude in one direction from the base surface 2A of the plate fin 2, the press surface is the base surface. The plate fins 2 may be formed in one direction, facilitating the removal of the formed plate fins 2 and the conveyance of the fin material, and the plate fins 2 can be easily manufactured.

Thus, according to the present embodiment, the following effects can be obtained.
The row-direction ridges 5 and the step-wise ridges 6 provided on the plate fins 2 can generate a sufficient turbulent flow that can destroy the temperature boundary layer of the air flow, thereby improving the heat transfer coefficient. Can do.
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.
Moreover, 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.

In addition, the airflow flowing between the plate fins 2 by the downward inclined surface toward the tube hole 3 of the three-dimensional mountain portion provided in both the row direction and the step direction provided between the tube holes 3 adjacent in the step direction. Since the effective heat transfer area can be increased by reducing the dead water area of the plate fin 2 by flowing around the heat transfer tube 4 immediately after the heat transfer tube 4, 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.

  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, since the flat portions 5E and 5F can be used as gripping portions when the plate fins 2 are manufactured by pressing, the manufacture of the fins can be facilitated.

  Further, since the collar 3A of the tube hole 3 through which the heat transfer tube 4 passes, the row direction ridges 5, and the step direction ridges 6 are projected in one direction from the base surface of the plate fin 2, the press surface is one of the bases. The plate fins 2 may be formed in the direction, facilitating the production of the plate fins 2 such as taking out the formed plate fins 2 and transporting the fin material, and improving the fin productivity.

In addition, in 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. It is an AA cross-section equivalent view of the plate fin shown in FIG. It is a BB cross-section equivalent figure of the plate fin shown in FIG. It is explanatory drawing of the air flow direction X for the heat flow analysis of the plate fin shown in FIG. 2, and its cross-sectional position. It is a distribution map of the local heat transfer coefficient of the surface of a fin, and a back surface in the cross-sectional 1 position of the air flow direction X (mm) shown in FIG. FIG. 6 is a distribution diagram of local / average heat transfer coefficient ratios on the front and back surfaces of the fin at the position of the cross section 1 in the air flow direction X (mm) shown in FIG. 5. It is a velocity vector distribution map in the fin upper surface 0.2mm position of the plate fin shown in FIG. It is explanatory drawing showing the ineffective heat-transfer area | region just after the heat-transfer tube of the plate fin shown in FIG.

Explanation of symbols

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 Central peak part 5E, 5F Flat part 6 Step direction peak part

Claims (7)

Plate fins that are arranged in parallel at a predetermined pitch and through which airflow flows,
In a fin-and-tube heat exchanger having a heat transfer tube, which is inserted in close contact with tube holes provided at a predetermined row pitch and step pitch in the plate fin and through which a fluid flows.
A fin-and-tube heat exchanger, wherein the plate fin is provided with a stepwise mountain portion along the step direction between the tube holes adjacent to each other in the step direction. Plate fins that are arranged in parallel at a predetermined pitch and through which airflow flows,
In a fin-and-tube heat exchanger having a heat transfer tube, which is inserted in close contact with tube holes provided at a predetermined row pitch and step pitch in the plate fin and through which a fluid flows.
The plate fin is provided with at least three or more row ridges along the row direction for each row of the tube holes,
The fins and tubes type heat exchanger characterized in that the row ridges are formed such that the heights of both ridges formed at both ends in the row direction are lower than the height of the central ridge formed therebetween. . The plate fin is provided with a step ridge along the step direction between the tube holes adjacent in the step direction together with the row ridge along the row direction.
The fin-and-tube heat exchanger according to claim 2, wherein a three-dimensional mountain portion protruding in both the row direction and the step direction is provided between the tube holes adjacent to each other in the step direction. . Four ridges in the row direction are formed,
4. The height of two central peaks formed between the peak portions in the row direction is higher than the height of peak portions formed at both ends in the row direction. 5. A fin-and-tube heat exchanger described in 1.   The fin and tube type according to any one of claims 2 to 4, wherein a width along a column direction of a central mountain part formed therebetween is wider than a width of both peak parts along the column direction. Heat exchanger.   The fin-and-tube heat exchanger according to any one of claims 1 to 5, wherein the plate fin is provided with a flat portion at least on an end surface on the inflow side of the airflow. The fin-and-tube heat exchanger according to any one of claims 1 to 7, wherein each of the peak portions protrudes in one direction from a base surface of the plate fin.

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