JP2523618B2 - Heat exchanger with fins - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger with fins used in air conditioners, refrigeration equipment and the like.

2. Description of the Related Art In recent years, the performance of finned heat exchangers has been remarkably improved, and finned heat exchangers having corrugated fins having a large air-side heat transfer area have already been put into practical use.

Hereinafter, the conventional finned heat exchanger will be described with reference to the drawings.

FIG. 4 shows a schematic shape of a finned heat exchanger according to the present invention, and FIGS. 5 and 6 show fin shapes of a conventional finned heat exchanger. In FIGS. 4 to 6, reference numeral 1 is a flat heat transfer tube bent in a meandering shape and provided with straight pipe portions 1 ′ substantially in parallel. Reference numeral 2 denotes fins provided between the straight tube portions 1 ′ facing each other of the heat transfer tube 1, which are fixed to the heat transfer tube 1 at a fin pitch Pa having a wave shape at regular intervals.
Reference numeral 3 denotes a cut-and-raised surface provided on the surface of the fin 2 in parallel with the airflow A direction. ′ Are also formed in the same direction with the same cut and raised pattern.

The operation of the heat exchanger with the fin configured as described above will be described below with reference to FIGS. 4 to 7.

Heat exchange is performed between the fins 2 and the heat transfer tubes 1 between the airflow A flowing between the fins 2 and the heat medium flowing in the heat transfer tubes 1. At that time, since the cut-and-raised surface 3 is provided on the surface of the fin 2 and the fin 2 is divided in the direction of the air flow A, the development of the temperature boundary layer a of the air flow A generated on the surface of the fin 2 is suppressed, and the air flow A The heat transfer coefficient between the fins 2 and the fins 2 is improved.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described configuration, as shown in FIG. 7, the temperature boundary layer a of the air flow A formed by the cut-and-raised surface 3 on the upstream side has the cut-and-raised surface 3 on the downstream side. The temperature boundary layer a gradually develops toward the downstream side, and the heat transfer coefficient between the fins 2 and the air flow A decreases toward the downstream side. It was

The present invention is concerned with the above problems, and provides a heat exchanger with fins, which maintains a high heat transfer coefficient with an airflow in the entire region from the upstream fins to the downstream fins and has excellent heat exchange performance.

Means for Solving the Problems In order to solve the above problems, the heat exchanger with fins of the present invention is configured such that a cut and raised surface parallel to the air flow direction passing between fins is continuously cut from the fin surface in the air flow direction. It is provided upright, and the cut and raised height from the fin direction of the cut and raised surface is made to meander by changing in a stepwise manner in multiple steps in the air flow direction,
It is provided with a configuration in which a flow path between fins is provided by repeatedly expanding and reducing the distance between fins in the air flow direction.

Effect According to the present invention, since the flow path between fins is repeatedly expanded and contracted by the above-described configuration, a pressure difference is generated on both sides of the fin when the airflow passes between the fins. A part of the airflow is contracted and flows into the gap between the surfaces, and the contracted flow completely cuts off the development of the temperature boundary layer of the airflow generated on the surface of the surface, and the heat between the airflow and the fins is cut off. The transmission rate can be maintained extremely high.

Example A heat exchanger with fins according to an example of the present invention will be described below with reference to the drawings.

1 and 2 show the fin shape of the finned heat exchanger in one embodiment of the present invention. 1 and 2
In the figure, reference numeral 4 denotes a heat transfer tube having the same structure as that of the conventional example and provided with a straight tube portion 4 '. Reference numeral 5 is a fin provided between the straight pipe portions 4'of the heat transfer tube 4, and is fixed to the heat transfer tube 4 in a wave shape at a constant fin pitch pb interval. Reference numeral 6 is a cut-and-raised surface provided on both sides of the fin 5, and is provided by cutting and raised from the surface of the fin 5 with a width wb so as to be parallel to the air flow B direction flowing between the fins 5, and the fin 5 of the cut-and-raised surface 6 The cut-and-raised heights h1 and h2 are formed in two steps of 1/5 and 2/5 of the fin pitch Pb on both sides, respectively. The surface 6 forms a meandering pattern indicated by a polygonal line m while changing by a dimension of 1/5 of the fin pitch Pb. Further, the arrangement pattern of the cut-and-raised surfaces 6 is provided so as to be line-symmetrical with the center line n between the fins with the adjacent fins 5 interposed therebetween, and the distance between the fins with the adjacent fins is between the fins which repeats expansion and contraction. A flow path is formed.

Regarding the finned heat exchanger configured as described above,
The operation will be described below with reference to FIGS. 1 to 3.

Heat exchange is performed between the airflow B flowing between the fins 5 and the heat medium flowing in the heat transfer tubes 4 via the fins 5 and the heat transfer tubes 4. At that time, since the airflow B flows through the inter-fin flow path in which the inter-fin distance is repeatedly expanded and contracted, a pressure difference is generated on both sides of the fin 5, and the cut-raised surfaces 6 arranged in a stepwise manner due to this pressure difference. A part of the airflow B is contracted and flows into the gap s between them, and this contracted flow completely divides the development of the temperature boundary layer b of the airflow B generated on the surface of the cut and raised surface 6. The heat transfer coefficient between the fins 5 and the air flow B can be kept extremely high.

Further, all the gaps s between the cut-and-raised surfaces 6 are formed to have the same size, and the flow paths between the fins are also symmetrical in the direction of the air flow B, so that all the gaps s are uniformly contracted. A uniform flow can be obtained, and a substantially uniform heat transfer coefficient can be obtained on any of the cut and raised surfaces 6.

EFFECTS OF THE INVENTION As described above, according to the present invention, a cut-and-raised surface parallel to the airflow direction passing between fins is continuously cut and raised from the fin surface in the airflow direction, and the cut-and-raised surface is cut and raised from the fin surface. By changing the height in a stepwise manner in multiple steps in the airflow direction to meander and forming a fin-to-fin flow path that repeatedly expands and contracts the inter-fin distance in the airflow direction, fins are formed when the airflow passes between fins. Since a pressure difference is generated on both surfaces of the cut-and-raised surface, a part of the airflow is contracted and flows into the gap between the cut-and-raised surfaces formed in a stepwise manner, and the temperature boundary of the airflow generated on the cut-and-raised surface surface The layer development is completely decoupled and the heat transfer coefficient between the air flow and the fins can be kept very high.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part showing a fin shape of a heat exchanger with fins according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the main part of FIG. 1, and FIG. 3 is a temperature of an air flow in FIG. FIG. 4 is a perspective view showing a schematic shape of a finned heat exchanger according to the present invention, and FIG. 5 is a principal part showing a fin shape of a conventional finned heat exchanger. FIG. 6 is a perspective view, FIG. 6 is a cross-sectional view of an essential part of FIG. 5, and FIG. 4 ... Heat transfer tube, 5 ... Fin, 6 ... Cut and raised surface.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shinichi Ide 3-22 Takaida Hondori, Higashi Osaka City Matsushita Refrigerator Co., Ltd. (72) Hiroaki Kase 3-22 Takaida Hondori, Higashi Osaka (56) References Actual Open Sho-58-21788 (JP, U) Actual Open Sho-56-117289 (JP, U) Actual Public Sho-62-5582 (JP, Y2)

Claims (3)

(57) [Claims] 1. A heat transfer tube and fins fixed to the heat transfer tube, wherein cut and raised surfaces parallel to the air flow direction passing between the fins are continuously cut and raised from the fin surfaces in the air flow direction. The inter-fin flow path is formed by changing the cut-and-raised height of the cut-and-raised surface from the fin surface in a stepwise manner in a multi-step manner in the airflow direction to meander to repeatedly expand and contract the inter-fin distance in the airflow direction. A heat exchanger with fins. 2. A patent characterized in that a cut-and-raised pattern of a cut-and-raised surface is provided in line symmetry with adjacent fins sandwiching a center line between the fins to form bilaterally symmetrical fin flow paths in the air flow direction. The heat exchanger with fins according to claim 1. 3. The fins of the cut-and-raised surface are formed in two steps on each surface, and the fin surfaces not cut and raised together form a five-step cut-and-raised surface on both sides, and the fins are formed. The heat exchanger with fins according to claim 1 or 2, wherein the cut-and-raised height is changed stepwise by a dimension of 1/5 of a pitch.