JP3322292B2 - Heat transfer tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat transfer tube used for heat exchange and the like, and more particularly to a heat transfer tube most suitable for a heat exchanger of a heat pump air conditioner.

[0002]

2. Description of the Related Art In a heat exchanger used for a refrigerator, an air conditioner, a heat pump, or the like, a refrigerant is circulated in a pipe, and the refrigerant is condensed in the pipe to perform necessary heat exchange. Heat transfer tubes are used. The inner surface of such a heat transfer tube was smooth and unprocessed in the early days. However, with the progress of thermodynamic research, it has been obtained that the inner surface of the pipe is not kept smooth, and that the formation of irregularities improves the heat transfer coefficient.

[0003] Recently, as shown in FIG.
There is a tendency for the mainstream to have a spiral continuous groove 12 (including a groove perpendicular to the tube axis direction) formed on the inner surface. One effect of providing such a spiral continuous groove 12 is that the heat transfer area can be increased by increasing the surface area of the inner surface of the tube. In addition, the presence of the helical irregularities in the pipe has the effect that the flowing refrigerant is agitated and turbulent, thereby improving the heat transfer coefficient. In other words, when exchanging heat by boiling the refrigerant in the pipe,
The refrigerant liquid flowing in the pipe is swept up along the spiral continuous groove 12, and the entire pipe inner surface is wetted with the refrigerant liquid, so that the heat transfer coefficient can be improved.

[0004]

However, as described above, a heat transfer tube provided with a spiral continuous groove has excellent heat transfer characteristics. However, good results are not always obtained in all cases. In particular, when a refrigerant is condensed and used in a pipe, there are the following problems. In other words, the refrigerant liquid condensed in the pipe accumulates below the pipe due to gravity and flows under the pipe, but the flow of the liquefied refrigerant does not go smoothly due to the presence of the spiral groove, and is lifted up by the spiral groove. A phenomenon occurs, resulting in wetting of the entire tube inner surface. When the inner surface of the pipe is wet, the inner wall surface of the pipe does not come into direct contact with the refrigerant vapor as a gas, and the heat transfer coefficient may be significantly reduced.

[0005] Therefore, in the case of a heat transfer tube for condensation, it is desired that the inner wall surface of the tube and the refrigerant vapor can directly contact each other in a larger surface area. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a heat transfer tube capable of greatly increasing the amount of heat exchange.

[0006]

In order to achieve the above-mentioned object, the present invention provides a transmission system in which a refrigerant used for evaporation or condensation flows and a projection for stirring the refrigerant is provided on the inner surface of the tube. In the heat tube, the protrusion is formed to face the flow of the refrigerant during evaporation, and the recess is provided on the opposite side of the protrusion and is formed to face the flow of the refrigerant during condensation. Is provided.

According to the above-described means, in the heat transfer tube used for both evaporation and condensation, the refrigerant flows from the opposite direction during the condensation to the evaporation. The projection is provided with a convex portion on the side facing the refrigerant flow during evaporation, and a concave portion is provided on the side facing the refrigerant flow during condensation. by this,
During evaporation, the pressure loss to the refrigerant flow is reduced and turbulence is generated, and the turbulence thereby increases the stirring effect and improves the heat transfer coefficient of evaporation. Further, at the time of condensation, a large turbulence occurs in the refrigerant flow to improve the heat transfer coefficient of condensation.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the heat transfer tube according to the present invention. In the heat transfer tube 1 according to the present invention, protrusions 3 are formed in a zigzag pattern on the inner wall surface of a metal tube 2. The refrigerant flows through the pipe 2, and the flow direction of the refrigerant is opposite during evaporation and condensation. Reference numeral 4 denotes a refrigerant flow at the time of evaporation, and reference numeral 5 denotes a refrigerant flow at the time of condensation.
The projection 3 has an arc shape, and the protrusion 3a is directed to the refrigerant flow 4 during evaporation, and the recess 3b is directed to the refrigerant flow 5 during condensation.

In such a configuration, during evaporation, the refrigerant flow 4 flows from left to right in FIG. 1 and, as shown in FIG.
Is formed in the direction of. In this flow, since the refrigerant flows along the peripheral shape, no pressure loss occurs. Also, when the flow 6 gets over the protrusions 3, the flow separates, causing turbulence, thereby greatly improving the heat transfer coefficient of evaporation.

At the time of condensation, as shown in FIG. 3, a flow 7 is formed in the direction from the concave portion 3b to the convex portion 3a of the projection 3. At this time, the recess 3b has a surface facing the flow 7 of U
The flow 8 converges on the upper surface of the projection 3 because of the
Occurs. Due to the strong turbulence generated when the stream 8 gets over the projection 3, the condensing heat transfer coefficient can be greatly improved.

As described above, by elaborating the shape of the projection 3, the heat transfer coefficient can be greatly improved both during evaporation and during condensation.

In the above-described embodiment, a metal tube is used as the heat transfer tube 1. However, the present invention is not limited to the metal tube, but may be a resin tube, a porcelain tube, a glass tube, or the like.

[0013]

As is clear from the above, according to the present invention, the projection provided in the pipe is provided with a projection formed so as to oppose the flow of the refrigerant during evaporation, and provided on the opposite side of the projection. And a concave portion formed so as to oppose the flow of the refrigerant at the time of condensation, so that during evaporation, the pressure loss to the refrigerant flow is reduced and turbulence is generated, and the turbulence thereby increases the stirring effect. Improve the heat transfer coefficient of evaporation. Further, at the time of condensation, a large turbulence occurs in the refrigerant flow to improve the heat transfer coefficient of condensation. As a result, it is possible to reduce the size of the apparatus, reduce equipment costs and running costs, and the like.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a heat transfer tube according to the present invention.

FIG. 2 is an explanatory diagram showing a path when a refrigerant for evaporation flows to a projection shown in FIG. 1;

FIG. 3 is an explanatory diagram showing a path when a condensing refrigerant flows to a projection shown in FIG. 1;

FIG. 4 is a cross-sectional view illustrating a configuration of a conventional heat transfer tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat transfer tube 2 Tube body 3 Projection 3a Convex part 3b Concave part 4 Refrigerant flow at the time of evaporation 5 Refrigerant flow at the time of condensation 6, 7, 8 flow

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-213495 (JP, A) JP-A-61-175486 (JP, A) JP-A-62-102093 (JP, A) 39183 (JP, U) JP 5-25174 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F28F 1/40 F28F 1/42

Claims (1)

(57) [Claims] 1. A heat transfer tube in which a refrigerant used for evaporation or condensation flows and a projection for stirring the refrigerant is provided on an inner surface of the pipe, wherein the projection faces the flow of the refrigerant during evaporation. And a concave portion provided on the opposite side of the convex portion so as to face the flow of the refrigerant during condensation.