JPS6086390A - Heat transfer tube equipped with fin - Google Patents

Abstract

PURPOSE:To prevent the deterioration of heat transfer performance by a method wherein the arranging spaces between respective fins are set so as to be increased stepwisely from the upstream side to the downstream side along the flow of fluid at the outside of the heat tranfer tube, equipped with fins and utilized for a heat exchanger or the like for air conditioner or the like. CONSTITUTION:A plurality of steps of flat heat transfer tubes 1 are provided in up-and-down direction and a multitude of needle-like fins 3-1, 3-2,...,3-n are arranged between the flat heat transfer tubes 1 neighboring in up-and-down direction. The spaces P1, P2, P3,...Pi...Pn between the needle-like fins 3-1, 3-2,..., 3-n along the flow direction of air 3 are set so as to keep the relations of P1 <P2<P3...<Pi...<Pn or increased stepwisely from the upstream side to the downstream side. Accordingly, temperature boundary layers of the same degree are developed around respective needle-like fins or the like and, therefore, the heat transfer performance may be improved without deteriorating the heat transfer characteristics of the needle-like fins located at the downstread side.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in finned heat exchanger tubes for air conditioning heat exchangers, air cooling heat exchangers, air preheaters, air (gas) heating coolers, and the like.

In the field of air heat exchangers, there are some that use wire-like fins (hereinafter referred to as needle-like fins) with a diameter of 111111 mm or less on the air-side heat transfer surface. In this case, an overview of the case where flat heat exchanger tubes are used as the heat exchanger tubes is given in Part 1.
This will be explained with reference to FIGS. 3 to 3.

FIG. 1 is a perspective view showing the structure of a conventional heat exchanger tube with wire fins, in which a large number of needle fins 2 are arranged between adjacent ones of multiple stages (three stages in this example) of flat heat exchanger tubes l. As shown in FIG. 2, they are arranged at regular intervals, forming a row parallel to the flow direction of the air 3 (arrow direction) and a row perpendicular thereto.

There is a liquid or gas inside the heat exchanger tube 1.
A heating source or a cold source is supplied, and air 3 flowing outside in the direction of the arrow is heated or cooled through the heat transfer tubes 1 and needle fins 2, thereby performing heat exchange.

During this heat exchange, the flow of air 3 is as shown in Figure 3.
During heat transfer through the needle fins 2, a temperature boundary layer 4 is formed around the needle fins 2, and the temperature boundary layer 4 is larger around the needle fins 2 on the downstream side than that around the wire fins 2 on the upstream side.
-1 + 2-2 develops thicker, so the wire fins 2-1 and 2-2 on the downstream side have poorer heat transfer characteristics, resulting in lower heat transfer performance. The finned heat exchanger tube had one.

The present invention eliminates the drawbacks of the conventional finned heat exchanger tubes,
This was proposed for the purpose of providing a finned heat exchanger tube with excellent heat transfer performance.In a wire finned or flat finned heat exchanger tube, the arrangement interval of each fin is adjusted along the flow of fluid outside the heat exchanger tube. This relates to a finned heat exchanger tube characterized in that the heat exchanger tube becomes larger in stages from the upstream side to the downstream side.

Hereinafter, the present invention will be specifically explained using an embodiment shown in FIG.

In the figure, reference numeral 1 denotes a flat heat exchanger tube (designated with the same reference numeral) having almost the same structure as the flat transfer tube described above;
are provided in multiple stages in the vertical direction, and a large number of needle-like fins are arranged between upper and lower adjacent flat heat exchanger tubes, which is almost the same as the conventional one, but the present invention The structure differs from the above-mentioned conventional one in that special consideration has been taken to the arrangement of the needle-like fins. That is, in the present invention, as shown in FIG. 4, needle-like fins 3-] + 3-2 + 3-3 are arranged in a row along the flow direction (arrow direction) of the air 3.
+3-4 +--3-n interval P] + P2
+ P3 + =-Pi -Pn, PI < P2 (
As there is a relationship of P3---<Pi---<Pn,
It is characterized by a configuration in which it changes in stages and is set larger from the upstream side to the downstream side. Note that the spacing between the diagonal fins in the direction perpendicular to the flow direction of the air 3 is set equal to (-<) as in the conventional one.

In the present invention, as described above (because the interval between the wire fins is set to increase stepwise from the upstream side to the downstream side of the air flow, each needle fin 3-1 + 3
-2 + 3-3, etc., a temperature boundary layer of the same degree develops, and the heat transfer performance of the needle-like fins located on the downstream side is improved without degrading the heat transfer characteristics.

Therefore, according to the present invention, the drawbacks of the conventional finned heat exchanger tubes can be overcome, and a practical effect can be achieved in that a finned heat exchanger tube with excellent heat transfer performance can be realized. Next, in another embodiment of the present invention shown in FIG. 5, the fin spacing li s II 2113 etc. is changed stepwise in the flow direction of the air 3 every several needle fins 4-2. ,7t<l
z＜A! Although this embodiment is different in that it is constructed as shown in FIG.

In addition, although the above-mentioned each example showed the example using a needle-like fin, it may replace with a needle-like fin and may use a plate-like fin.

[Brief explanation of drawings]

Figure 1 is a perspective view of a conventional finned heat exchanger tube, Figure 2 is a cross-sectional view taken along nm-m5 in Figure 1, and Figure 3 is the formation of temperature boundaries around the fins of a conventional finned heat exchanger tube. Aspect explanatory diagram,
FIG. 4 is a sectional view corresponding to FIG. 2 of an embodiment of the present invention;
FIG. 5 is a sectional view corresponding to FIG. 2 of another embodiment of the present invention. 1: Flat heat transfer tube, 2.2-112-2---: Needle fin, 3: Air, 3-1 + 3-2 + 3-3---
-: Needle fin, 4-2: Needle fin.

Claims (1)

[Claims] A heat exchanger tube with needle-like fins or flat plate-like fins, characterized in that the interval between the fins is gradually increased from the upstream side to the downstream side along the flow of fluid outside the heat exchanger tube. Heat exchanger tube.