JPS6099998A - Heat transfer tube equipped with internal surface rib - Google Patents

Abstract

PURPOSE:To permit to maintain the heat transfer performance of high degree for a long period of time by a method wherein protuberances for preventing errosion are provided at the downstream side of the internal surface ribs in the heat transfer tube through which a fluid containing corrosive factors is flowed. CONSTITUTION:The heat transfer tube 6' is arranged in the enclosed vessel 3a of a condenser 3 and cooling water, including corrosive factors, flows therethrough into the direction of arrow signs. The rib 10, provided with spiral small protuberance, not parallel to the flow direction of the cooling water, is formed on the internal surface of the heat transfer tube 6'. The sectional configuration of the rib 10 is formed so as to have a gentle slope 11a at the downstream side of the protuberance 11 with respect to the flow of cooling water as shown by the non-symmetrical protuberance 11 in the diagram. In the heat transfer tube 6' formed with the rib 10, the cooling water flows along the gentle slope 11a after passing the apex of the protuberance 11 of the rib 10 when the cooling water flows into the direction of the arrow sign, therefore, a local turbulent flow will never be generated and there is few passibility to generate the corrosion of the inner wall of the tube due to water corrosion effect or so-called errosion. According to this method, reliability as the heat transfer tube for the condenser 3 becomes high and the heat exchanging performance of high degree may be maintained for a long period of time.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to heat exchanger tubes with internal ribs, and more particularly.

The present invention relates to a heat exchanger tube with internal ribs suitable for use in a refrigerator or the like that handles a fluid to be cooled or cooled that contains corrosive factors.

[Background of the invention]

First, regarding the prior art, Figures 1 to 3 are hammered with a φ throat I. Figure 1 is a partial cross-sectional schematic diagram showing the refrigeration cycle of a typical centrifugal refrigerator, and Figure 2 is a FIG. 3 is a cross-sectional view of a conventional heat exchanger tube with internal ribs, and is a cross-sectional view of a main part showing a cross-sectional shape of a conventional symmetrical rib.

In FIG. 1, 1 is an evaporator, 2 is a turbo compressor, 3 is a condenser, and 4 is an expansion valve. These are connected by a refrigerant pipe 7 to form a refrigeration cycle of a turbo refrigerator. Arrows in the refrigerant pipe 7 indicate the direction of flow of the refrigerant. 5
6 is a heat exchanger tube in the evaporator 1, and 6 is a heat exchanger tube in the condenser 3.

The condenser 3 is a multi-tube heat exchanger in which a large number of heat transfer tubes 6 through which cooling water flows are arranged inside a closed container 3a through which a refrigerant flows, 3b is a cooling water inlet, and 3c is a cooling water inlet. It is a discharge port.

As shown in FIG. 2, the heat exchanger tube 6 is provided with so-called ribs 8, which are small protrusions that are not parallel to the flow direction of the flowing fluid, on the inner surface of the tube. The rib 8 is formed in a spiral shape on the inner surface of the heat exchanger tube 6.

As shown in FIG. 3, the rib 8 has a cross-sectional shape similar to a substantially symmetrical protrusion 9. The arrows in Figures 2-3 indicate the direction of flow of cooling water.

The operation of the turbo chiller configured in this way will be explained.

In the evaporator 1, a low-temperature, low-pressure liquid refrigerant removes heat from the fluid flowing through the heat transfer tubes 5, evaporates, and provides low-temperature flow to the outside.

The evaporated refrigerant is compressed by the turbo compressor 2 and becomes a high-temperature, high-pressure cooling gas that reaches the condenser 3. Here, while the refrigerant gas passes through the closed container 3a, it enters from the suction port 3b, flows through the heat transfer tube 6, and exchanges heat with the cooling water that flows from the discharge port 3c to the outside of the condenser 3 in the direction of the arrow, and is condensed and liquefied. , the pressure is reduced through the expansion valve 4, and it returns to the evaporator 1, whereupon this cycle is repeated to perform the refrigeration function.

By the way, the cooling water supplied to the condenser 3 generally contains some corrosive factors.

Conventionally, as a means of improving heat transfer, it has been known to provide ribs 8 on the inner surface of the tube that are not parallel to the flow direction of the fluid flowing through the tube as described above. In this case, there is a problem in that localized lotion tends to occur on the downstream side of the rib 8. In particular, as shown in FIG. 3, a rib shaped like a symmetrical protrusion 9 causes local turbulence on the downstream side of the protrusion 9, causing corrosion of the inner wall of the pipe due to water erosion. was there.

[Purpose of the invention]

The present invention has been made in order to solve the above-mentioned problems of the prior art, and is capable of preventing double lotion that tends to occur on the downstream side of the inner rib in a heat exchanger tube through which a fluid containing a corrosive factor flows. The object is to provide a heat exchanger tube with internal ribs having a protrusion shape.

[Summary of the invention]

The structure of the heat transfer tube with internal ribs according to the present invention is such that the heat transfer tube with internal ribs is provided with ribs that are not parallel to the flow direction of the fluid on the inner surface of the tube through which a fluid containing a corrosion factor flows. The shape is formed into a protrusion shape having a gentle slope on the downstream side of the rib with respect to the flow direction of the fluid.

As an additional note, 1. Since the 20-john is caused by local turbulence generated immediately downstream of the protrusion, the shape of the protrusion of the rib on the inner surface of the heat exchanger tube has a gentle slope on the downstream side. This is intended to prevent the occurrence of two lotions.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained in accordance with FIG.
This will be explained with reference to the figures and FIG.

FIG. 4 is a sectional view of a heat exchanger tube with internal ribs according to an embodiment of the present invention, and FIG. 5 is a sectional view of essential parts showing the cross-sectional shape of the ribs in FIG. 4. Arrows in the figure indicate the direction of fluid flow.

In FIG. 4, reference numeral 6' denotes a heat transfer tube, which is disposed within the closed container 3a of the condenser 3 shown in FIG. 1, through which cooling water containing corrosion factors flows in the direction of the arrow. Reference numeral 10 denotes a rib, which forms a small spiral protrusion that is not parallel to the flow direction of the cooling water on the inner surface of the heat transfer tube 6'. The cross-sectional shape of the rib 10 is formed in such a shape that a gentle gradient device 1a is provided on the downstream side of the protrusion 11 with respect to the flow of cooling water, like the asymmetric protrusion 11 shown in FIG. .

In the heat exchanger tube 6' in which the rib 10 of such a shape is formed,
When the cooling water flows in the direction of the arrow, the protrusion 11 of the rib 10
Since the pipe flows along the gentle gradient device 1a even after passing the 01 point, local turbulence does not occur, and there is little risk of corrosion of the inner wall of the pipe due to water erosion, so-called 20-john.

Due to its stiffness, it is highly reliable as a heat transfer tube for condenser 3.
High heat exchange performance can be maintained for a long period of time, which greatly contributes to improving the performance of centrifugal chillers.

In the above embodiment, an example of a heat transfer tube used in a condenser of a centrifugal chiller was explained, but the present invention is not limited to a condenser of a centrifugal chiller, but can be applied to a heat exchanger tube used in a product that can be expected to have the same effect. It is a general-purpose item in the range of heat tubes.

Furthermore, in the above embodiments, the ribs of the heat exchanger tubes are continuously formed in a spiral shape, but the present invention is limited to this. Even if the heat exchanger tube is formed intermittently, such as ribs provided at intervals like bamboo nodes, it has the characteristics of the present invention and satisfies the workability and heat exchange performance. Needless to say, it's a good thing.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a heat exchanger tube with internal ribs that has a small risk of erosion occurring on the downstream side of the internal ribs, even in a heat exchanger tube through which a fluid containing a corrosive factor flows. It is possible to maintain high heat transfer performance for a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a schematic partial cross-sectional configuration diagram showing the refrigeration cycle of a typical centrifugal refrigerator, Fig. 2 is a sectional view of a conventional heat exchanger tube with internal ribs, and Fig. 3 is a conventional symmetrical ribbed heat transfer tube. 4 is a cross-sectional view of a heat exchanger tube with internal ribs according to an embodiment of the present invention, and FIG. 5 is a cross-sectional view of a main part showing a cross-sectional shape of the ribs in FIG. 4. It is a diagram. 6′...Heat transfer tube, ]0...Rib, 11...Protrusion,
lla... Gradient.

Claims (1)

[Claims] 1. In a heat exchanger tube with internal ribs provided on the inner surface of the tube through which a fluid containing a corrosion factor flows, ribs that are not parallel to the flow direction of the fluid, the cross-sectional shape of the ribs on a cross section parallel to the tube axis is . A heat exchanger tube with internal ribs, characterized in that a protrusion shape having a gentle slope is formed on the downstream side of the rib with respect to the flow direction of the fluid, the protrusion shape being used to prevent the generation of double lotion.