JP2014126212A - Fin tube heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fin tube heat exchanger having excellent basic performance without providing cut and raised parts.SOLUTION: A fin tube heat exchanger includes: a plurality of stacked fins 31; and heat transfer tubes 21 penetrating the fins. Each of the fins is a V-corrugated fin having peaks and troughs formed along an air flow direction, and an area of a first inclined portion 36 on a windward side of the fin is larger than that of a second inclined portion 38 on a leeward side thereof. It is thereby possible for the windward inclined portion having the larger area to secure a heat exchange amount (heat exchange capability), possible to eliminate a flow of gas from a front side to a back side of the fin generated by providing a cut and raised part or the like, and possible to avoid performance degradation due to closing of a channel at a time of operation accompanied by frosting.

Description

  The present invention relates to a finned tube heat exchanger.

  Generally, the fin tube heat exchanger is configured by a plurality of fins arranged at predetermined intervals and a heat transfer tube penetrating the plurality of fins. The air flows between the fins and exchanges heat with the fluid in the heat transfer tubes.

  9 to 12 are respectively a plan view of fins used in a conventional fin tube heat exchanger, a sectional view taken along line aa, a sectional view taken along line bb, and a line cc. FIG. The fin 1 is shape | molded so that the peak part 4 and the trough part 6 may appear alternately along an airflow direction. Such fins are generally called “corrugated fins”. According to the corrugated fin, not only the effect of increasing the heat transfer area but also the effect of thinning the temperature boundary layer by meandering the air flow 3 can be obtained.

  Moreover, as shown in FIGS. 13-15, the technique which improves heat-transfer performance by providing a corrugated fin with a raising and raising is also known (for example, refer patent document 1). Cut-and-raised 41a, 41b, 41c and 41d are provided on the fan inclined surfaces 42a, 42b, 42c and 42d of the fin 1. The heights H1, H2, H3, and H4 of the cut-and-raised portions 41a, 41b, 41c, and 41d are 1/5 · Fp ≦ (H1, H2, H3, H4) ≦ 1 when the distance between adjacent fins 1 is Fp. / 3 · Fp is satisfied.

  Patent Document 1 also describes another fin configured to reduce ventilation resistance during frosting operation as much as possible. As shown in FIGS. 16 to 18, the fin inclined surfaces 12 a and 12 b of the fin 1 are provided with cut-and-raised portions 11 a and 11 b that satisfy the above-described relationship. Since the number of times of bending of the fin 1 is small, the inclination angles of the fin inclined surfaces 12a and 12b are relatively gentle.

JP 11-125495 A

  However, since the conventional fin tube heat exchanger described in Patent Document 1 has a cut-and-raised portion, even if the cut-and-raised portion is sufficiently low, it adheres to the cut-and-raised portion during the frosting operation. At least 20% or more of the flow path is locally throttled by the frosting. For this reason, when the cut-and-raise is provided, even if the number of bendings is limited to one and the inclination angle is made gentle, a significant increase in ventilation resistance is inevitable. In order to reduce the ventilation resistance of the fin 1 shown in FIGS. 16 to 18 to a level equivalent to that of the fin shown in FIGS. 9 to 12, it is necessary to make the inclination angle of the fin 1 as close as possible to 0 °.

  The present invention has been made in view of such points, and provides a finned tube heat exchanger having excellent basic performance regardless of frosting operation and non-frosting operation without providing a cut and raised portion. The purpose is to do.

  In order to solve the conventional problem, a finned tube heat exchanger according to the present invention includes a plurality of stacked fins and a heat transfer tube penetrating the fins, and the fins have peaks and valleys along the airflow direction. The V corrugated shape is formed, and the area of the first inclined portion on the leeward side of the fin is larger than the area of the second inclined portion on the leeward side.

  As a result, it is possible to secure a heat exchange amount (heat exchange capability) by the large windward side inclined portion, and there is no flow of gas from the front side to the back side of the fin caused by providing a cut and raised, resulting in frost formation. During operation, it is possible to avoid performance degradation due to blockage of the flow path.

  ADVANTAGE OF THE INVENTION According to this invention, ventilation resistance can fully be suppressed and the finned-tube heat exchanger which has a high heat exchange amount (heat exchange capability) can be provided.

The perspective view of the finned-tube heat exchanger which concerns on Embodiment 1 of this invention The top view of the fin used for the fin tube heat exchanger of FIG. Sectional drawing along the aa line of the fin shown in FIG. Sectional drawing along the bb line of the fin shown in FIG. Sectional drawing along the cc line of the fin shown in FIG. The top view which shows the part which has a high heat transfer rate in the fin shown in FIG. The top view which shows the part which has a high heat transfer rate in the conventional fin The top view which shows the part which has a high heat transfer rate in the case where the windward and the leeward slope area of the fin are the same Top view of fins used in conventional fin tube heat exchanger Sectional drawing along the aa line of the fin shown in FIG. Sectional drawing along the bb line of the fin shown in FIG. Sectional drawing along the cc line of the fin shown in FIG. Top view of another fin used in a conventional fin tube heat exchanger Sectional drawing along the aa line of the fin shown in FIG. Sectional drawing along the bb line of the fin shown in FIG. Top view of yet another fin used in a conventional fin tube heat exchanger Sectional drawing along the aa line of the fin shown in FIG. Sectional drawing along the bb line of the fin shown in FIG.

  1st invention is equipped with the laminated | stacked several fin and the heat exchanger tube which penetrates the said fin, The said fin is a V corrugate shape by which a peak and a valley are shape | molded along an airflow direction, Comprising: The wind of the said fin The area of the first inclined portion on the upper side is configured to be larger than the area of the second inclined portion on the leeward side.

  As a result, it is possible to secure a heat exchange amount (heat exchange capability) by the large windward side inclined portion, and there is no flow of gas from the front side to the back side of the fin caused by providing a cut and raised, resulting in frost formation. During operation, it is possible to avoid performance degradation due to blockage of the flow path.

  According to a second invention, in the first invention, a radius is provided at a boundary portion between the windward side inclined surface and the leeward side inclined surface.

Thereby, the drainage of a fin can be improved and the avoidance of a performance fall can be made more effective.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments.

  As shown in FIG. 1, a finned tube heat exchanger 100 of the present embodiment has a plurality of fins 31 arranged in parallel to form a flow path of air A (gas), and penetrates these fins 31. The heat transfer tube 21 is provided. The finned tube heat exchanger 100 is configured to exchange heat between the medium B flowing inside the heat transfer tube 21 and the air A flowing along the surface of the fin 31. The medium B is a refrigerant such as carbon dioxide or hydrofluorocarbon. The heat transfer tube 21 may be connected to one or may be divided into a plurality.

  In this specification, the direction in which the fins 31 are arranged is defined as the height direction, the direction parallel to the front edge 30a is defined as the step direction, and the height direction and the direction perpendicular to the step direction are defined as the airflow direction (the flow direction of the air A). In other words, the step direction is a direction perpendicular to both the height direction and the airflow direction. The airflow direction is perpendicular to the longitudinal direction of the fins 31. The airflow direction, the height direction, and the step direction correspond to the X direction, the Y direction, and the Z direction, respectively.

  As shown in FIG. 2, the fin 31 typically has a rectangular and flat plate shape. The longitudinal direction of the fin 31 coincides with the step direction. In the present embodiment, the fins 31 are arranged at a constant interval (fin pitch FP). However, the interval between the two fins 31 adjacent to each other in the height direction (fin pitch FP) is not necessarily constant and may be different. The fin pitch FP can be adjusted to a range of 1.0 to 1.5 mm, for example.

  As shown in FIG. 3, the fin pitch FP is represented by the distance between two adjacent fins 31 and 31.

  The constant width portion including the front edge 30a and the constant width portion including the rear edge 30b are parallel to the airflow direction. However, these portions are portions used for fixing the fins 31 to the mold during molding, and do not greatly affect the performance of the fins 31.

  As a material for the fins 31, a flat plate made of aluminum having a thickness of 0.05 to 0.8 mm that has been punched can be suitably used. The surface of the fin 31 may be subjected to hydrophilic treatment such as boehmite treatment or application of a hydrophilic paint. It is also possible to perform a water repellent treatment instead of the hydrophilic treatment.

  A plurality of through holes 37h are formed in the fin 31 in a line and at equal intervals along the step direction. The heat transfer tube 21 is fitted in each of the plurality of through holes 37h. A fin collar 37 is formed by a part of the fin 31 around the through hole 37h, and the fin collar 37 and the heat transfer tube 21 are in close contact with each other. The diameter of the through hole 37h is, for example, 1 to 20 mm, and may be 4 mm or less. The diameter of the through-hole 37 h matches the outer diameter of the heat transfer tube 21. The distance (tube pitch) between two through holes 37h adjacent to each other in the step direction is, for example, 2 to 3 times the diameter of the through hole 37h. Moreover, the length of the fin 31 in an airflow direction is 15-25 mm, for example.

As shown in FIG.2 and FIG.3, the fin 31 is shape | molded so that the peak part 34 may appear only in one place along an airflow direction. The ridge line of the mountain portion 34 is parallel to the step direction. That is, the fin 31 is a fin called a corrugated fin. In the present embodiment, the fin 31 has only one peak portion 34 along the airflow direction. The front edge 30a and the rear edge 30b correspond to the valleys. In the airflow direction, the position of the mountain portion 34 is located leeward from the center of the heat transfer tube 21.

  The fin 31 is configured to prohibit the flow of air A from the front side (upper surface side) to the back side (lower surface side) of the fin 31 in other regions excluding the plurality of through holes 37h. That is, the fin 31 has no opening other than the through hole 37h. If there is no opening, there is no problem of clogging of the opening due to frost formation, which is advantageous from the viewpoint of pressure loss. Note that “no opening is provided” means that no slit, louver or the like is provided, that is, no hole penetrating the fin is provided.

  The fin 31 further includes a flat portion 35, a first inclined portion 36, a second inclined portion 38, and a third inclined portion 39. The flat portion 35 is a portion adjacent to the fin collar 37 and an annular portion formed around the through hole 37h. The surface of the flat part 35 is parallel to the airflow direction and perpendicular to the height direction. The first inclined portion 36 and the second inclined portion 38 are portions inclined with respect to the airflow direction so as to form a mountain portion 34.

  The first inclined portion 36 occupies the widest area in the fin 31. The 1st inclination part 36 is located across the reference line which passes along the center of the heat exchanger tube 21 in parallel with a step direction, and the 2nd inclination part is located in the leeward rather than a reference line. That is, the peak portion 34 is formed by the first slope portion 36 on the windward side and the second slope portion 38 on the leeward side. The third inclined portion 39 has the flat portion 35, the first inclined portion 36, and the second inclined portion 35 so as to eliminate the difference in height between the flat portion 35, the first inclined portion 36, and the second inclined portion 38. This is a portion where the inclined portion 38 is smoothly connected. The surface of the third inclined portion 39 is a gentle curved surface.

  An appropriate radius (for example, R0.5 mm to R2.0 mm) may be given to the boundary portion between the first inclined portion 36 and the second inclined portion 38 and the third inclined portion 39. Similarly, an appropriate radius (for example, R0.5 mm to R2.0 mm) may be given to the boundary portion between the peak portion 34 and the third inclined portion 39. Such a round improves the drainage of the fin 31.

  In addition, the 3rd inclination part 39 is a curved surface as a whole. The cross section of FIG. 4 is a cross section observed when the fins 31 are cut along a plane perpendicular to the step direction and passing through the center of the heat transfer tube 21. The cross section of FIG. 5 is a cross section observed when the fins 31 are cut along a plane perpendicular to the flow direction and passing through the center of the heat transfer tube.

  FIG. 6 shows the results obtained by numerical analysis for a V-shaped corrugated fin having only one peak. FIG. 7 shows the results obtained by numerical analysis for an M-shaped corrugated fin having two peaks. A portion having a high heat flux (heat exchange amount) is indicated by a thick line. As shown in FIG. 6, the heat flux at the leading edge 30a and the crest 34 is extremely high. Similarly, as shown in FIG. 7, the heat flux at the leading edge 30a and the crest 34 is extremely high. However, comparing the total length of the thick lines, the total length of the thick lines shown in FIG. 6 exceeds the total length of the thick lines shown in FIG. That is, the V-shaped corrugated fin can ensure a longer region of high heat flux. Further, in the present embodiment shown in FIG. 6, the crest 34 shown in FIG. 8 is located on a reference line that is parallel to the step direction and passes through the center of the heat transfer tube 21, and the first inclined portion 36 and the second inclined portion 38 The area of the high heat flux can be ensured longer by making the area of the first inclined portion 36 on the leeward side larger than the area of the second inclined portion 38 on the leeward side, compared to the case where the areas are the same. Therefore, in terms of heat transfer coefficient, the fin 31 of the present embodiment is advantageous over the conventional fin, and uses the fin 31 in which the area of the second inclined portion 38 is larger than that of the first inclined portion 36. This improves the average heat transfer coefficient.

INDUSTRIAL APPLICABILITY The present invention can provide a finned tube heat exchanger in which ventilation resistance is sufficiently suppressed and has a high heat exchange amount (heat exchange capacity), and is useful for a heat pump used in an air conditioner, a hot water supply device, a heating device, and the like. is there. In particular, it is useful for an evaporator for evaporating a refrigerant.

21 Heat transfer tube 30a Front edge 30b Rear edge 31 Fin 34 Mountain part 35 Flat part 36 First inclined part (windward inclined surface)
37 Fin collar 37h Through-hole 38 Second inclined part (leeward side inclined surface)
39 3rd inclined part 100 Fin tube heat exchanger

Claims (2)

The fin includes a plurality of laminated fins and a heat transfer tube penetrating the fin, and the fin has a V corrugated shape in which peaks and valleys are formed along the airflow direction, and the area of the windward inclined surface of the fin is A finned tube heat exchanger characterized by having a configuration larger than the area of the leeward inclined surface. The finned tube heat exchanger according to claim 1, wherein a rounded portion is provided at a boundary portion between the windward side inclined surface and the leeward side inclined surface.

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