JPS62112997A - Heat exchanger - Google Patents

Abstract

PURPOSE:To enable a high heat transfer rate on the average to be obtained even in the case of a heat exchanger elongate in the direction of a gas flow, by a construction wherein slit pieces having leading edge parts opposed to a gas flow are provided on the surfaces of fins, and base parts of each of the slit pieces are inclined to the inner side of the slit piece relative to the direction of the gas flow. CONSTITUTION:Heat is exchanged between a gas flow B passing between fins 5 and a heat-transmitting medium flowing in flat pipes 4, through the fins 5 and the pipes 4. A temperature boundary layer of the gas flow B formed on the surface of the fin 5 is split by slit pieces 6, so that the boundary layer is made to be thin. Since a slit part 6b of the slit piece 6 is parallel to the gas flow B, the draft resistance is not extremely increased by the slit pieces 6, and the gas flow B is not extremely biased while being led to the outside of both ends of the slit piece 6. In addition, since the gas flow B passing on the outside of both ends of the slit piece 6 is drawn to the inside of the slit piece 6 by base parts 6a provided at both ends of the slit piece 6, the gas flow passing through the interior of the slit piece 6 is accelerated, and a high heat transfer rate on the average can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat exchanger used in air conditioning equipment, refrigeration equipment, etc.

BACKGROUND OF THE INVENTION In recent years, there has been a remarkable improvement in the performance of heat exchangers, and heat exchangers equipped with wave-shaped fins characterized by a large heat transfer area on the air side have already been put into practical use.

The conventional heat exchanger mentioned above will be explained below with reference to the drawings.

5 to 9 show conventional heat exchangers. In FIGS. 6 to 9, reference numeral 1 denotes a flat tube bent in a meandering manner, and is provided with straight tube portions 1' parallel to each other in the vertical direction. Fins 2 are provided horizontally between the opposing straight pipe portions 1' of the flat tube 1, and are fixed to the flat tube 1 at regular intervals in a wave shape. A louver piece 3 is provided on the surface of the fin 2, and its front edge 3a faces the airflow A, and the louver surface 3b is inclined with respect to the airflow A.

The operation of the heat exchanger configured as above will be described below.

Heat exchange is performed between the airflow A flowing between the fins of the fins 2 and the heat medium flowing inside the flat tube 1 via the fins 2 and the flat tube 1. At this time, since a large number of louver pieces 3 are provided on the surface of the fin 2, the development of the temperature boundary layer of the airflow A generated on the surface of the fin 2 is interrupted, the thickness of the boundary layer becomes thinner, and the louver surface 3b is inclined. Even by changing the flow direction of the airflow A and turbulating the flow, a large amount of heat is transferred between the airflow 3 beso A and the fins 2.

Problems to be Solved by the Invention However, in the above configuration, since the ventilation resistance of the louver piece 3 is large, the airflow A is directed to the portion where the louver piece 3 is not present, that is, both ends of the louver piece 3, as shown in FIG. The temperature boundary layer of the airflow A cannot be sufficiently separated on the outside of both ends of the louver piece 30, and it becomes thicker as it goes downstream, and the speed of the airflow A flowing inside the louver piece 3 becomes slower. In addition, the temperature boundary layer formed on the surface of the louver piece 3 is also thick, which has the problem of extremely lowering the heat transfer coefficient, especially in the case of a heat exchanger that is long in the air inflow direction.

In view of the above-mentioned problems, the present invention provides a heat exchanger that can obtain a high average heat transfer coefficient even in a heat exchanger that is long in the direction of airflow.

Means for Solving the Problems In order to solve the above problems, the heat exchanger of the present invention has a slit piece provided on the fin surface with a front edge facing the airflow, and a leg of this slit piece facing the airflow direction. It has a structure in which the slit piece has an inwardly inclined side.

Effect: Due to the above-described configuration, the slit piece does not greatly change the direction of airflow, so there is less ventilation resistance than a louver piece, and the airflow flowing between the fins is directed to the part without the slit piece and both ends of the slit piece. The air does not flow extremely toward the outside of the air, and the legs at both ends of the slit are inclined toward the inside of the slit with respect to the airflow direction.
The airflow flowing on the outside of both ends of the slit piece is drawn to the inside of the slit piece, so the airflow flowing inside the slit piece is accelerated, and the slit piece has a large effect of dividing the temperature boundary layer of the airflow and thinning the boundary layer. As a result, the heat transfer coefficient between the airflow and the fins is greatly improved.

EXAMPLE Hereinafter, a heat exchanger according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a 6-page perspective view of a heat exchanger in an embodiment of the present invention. In FIG. 1, reference numeral 4 denotes a flat tube bent in a meandering manner, and is provided with straight tube portions 4' parallel to each other in the vertical direction. Fins 5 are provided horizontally between the opposing straight pipe portions 4' of the flat tube 4, and are fixed to the flat tube 4 at regular intervals in a wave shape. Reference numeral 6 denotes slit pieces provided on the surface of the fin 5, which are alternately provided on both sides of the fin 5 in the direction of the air flow B.

Further, the slit piece 6 is composed of a leg portion 6a and a slit portion 6b, and the leg portion 6a has an inclination toward the inside of the slit piece with respect to the direction of the airflow B.

The operation of the heat exchanger configured as above will be described below.

Heat exchange is performed between the airflow B flowing between the fins of the fins 6 and the heat medium flowing inside the flat tube 4 via the fins 5 and the flat tube 4. At this time, the temperature boundary layer of the airflow B generated on the surface of the fin 5 is divided by the slit piece 6, and the thickness of the boundary layer becomes thin. In addition, since the slit portion 6b of the slit piece 6 is parallel to the airflow B, it is unlikely that the ventilation resistance will be extremely increased. It does not flow excessively toward the outside. Moreover, the airflow B flowing on the outside of both ends of the slit piece 6 due to the legs 6a at both ends of the slit piece 6
is drawn to the inside of the slit piece 6, the airflow flowing inside the slit piece 6 is accelerated, and the airflow B
The temperature boundary layer becomes thinner, and airflow B and fin 5
The heat transfer coefficient does not decrease even if it goes downstream, and a high heat transfer coefficient can be obtained on average.

As described above, according to this embodiment, the slit piece 6 is provided on the surface of the fin 6, and the leg part 6a of the slit piece 6 is connected to the air flow B.
By inclining the slit piece 6 inward with respect to the direction, the heat transfer coefficient between the airflow B and the fins 60 does not decrease even when going downstream of the airflow B, and is large even in a heat exchanger that is long in the direction of the airflow B. Heat transfer performance is improved by maintaining the heat transfer coefficient.

Effects of the Invention As described above, the present invention provides a heat exchanger that is long in the airflow direction by providing slit pieces on the fin surface and inclining the legs of the slit pieces inward in the airflow direction. However, as it goes downstream, the heat transfer coefficient between the airflow and the fins does not decrease, making it possible to obtain a heat exchanger with excellent heat transfer performance.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part showing the fin shape of a heat exchanger according to an embodiment of the present invention, FIG. 2 is a perspective view of a main part of the heat exchanger shown in FIG. 1, and FIG. Figure 4 is a cross-sectional view taken along line C-C in Figure 1. Figure 6 is a perspective view showing the shape of a conventional heat exchanger.
The figure is a cross-sectional view of the main part showing the fin shape of Fig. 5, Fig. 7 is a perspective view of the main part of Fig. 6, and Fig. 8 is a wind speed distribution diagram of the airflow passing through the cross section taken along line F-F in Fig. 6. , Figure 9 is E-E of Figure 6.
FIG. 4... Flat tube, 6... Fin, 6...
...Slit piece, 6a... Leg, 6b...
...Slit part. Name of agent: Patent attorney Toshio Nakao and one other name
25! I

Claims (1)

[Claims] A flat tube bent in a meandering manner and a fin stacked in a wave shape between the flat tubes, a slit piece having a front edge facing the airflow is provided on the surface of the fin, and a leg portion of the slit piece is provided. A heat exchanger characterized in that the slit has an inclination toward the inside of the slit with respect to the airflow direction.