JPH0561557B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention provides a heat exchanger that is installed in a heat exchanger tube,
The present invention relates to a heat transfer promoting device including a spiral plate that makes the flow of fluid in a heat transfer tube a swirling flow.

(Prior Art) Some heat exchangers include heat exchanger tubes through which fluid flows, and the heat exchanger tubes are heated from the outside, or the heat exchanger tubes radiate heat to the outside for heat exchange.

As a device for promoting heat transfer in a heat exchanger equipped with such heat transfer tubes, the one shown in FIG. 3 is known.

In FIG. 3, a heat transfer accelerator 2 is installed inside the heat transfer tube 1.
is installed. The heat transfer accelerator 2 is composed of a spiral plate formed by twisting a long plate having the same width as the inner diameter of the heat transfer tube 1. With this heat transfer promoting device 2, the flow of the fluid flowing inside the heat transfer tube 1 becomes a swirling flow, the boundary layer of the heat transfer tube 1 becomes thinner, and heat transfer between the heat transfer tube 1 and the fluid is promoted.

(Problems to be Solved by the Invention) However, the conventional heat transfer accelerator 2 has the following problems.

That is, since the heat transfer accelerator 2 made of a spiral plate is installed over the entire radial area inside the heat transfer tube 1, this acts as a resistance to the fluid flowing inside the heat transfer tube 1, and the pressure caused by the heat transfer accelerator 2 is increased. The loss will become huge. For this reason, there was a problem in that the load on the pump that pumped the fluid increased.

On the other hand, there is also known a heat transfer accelerator having a structure in which a long plate having a width extremely smaller than the inner diameter of the heat exchanger tube is spirally twisted and attached to the inner circumferential surface of the heat exchanger tube. (Jikko 48
(Refer to Publication No. 13761) However, in the heat transfer accelerator made of the narrow spiral plate, the spiral plate is attached to only one location in a given cross section of the heat exchanger tube, so the ratio of the spiral plate to the inner area of the heat exchanger tube is The mounting density was low and the heat transfer promotion effect was not very good.

Furthermore, a heat transfer accelerator device is also known in which an opening is provided partially in the center of a spiral plate having the same diameter as the heat transfer tube. (Mr. Kimiaki
(Refer to Japanese Utility Model Publication No. 17-1131 and Japanese Utility Model Application No. 49-134772.) However, in the heat transfer accelerator made of a spiral plate with a partial opening in the center, the boundary layer is increased by the flow of fluid passing through the opening. This disturbs the heat transfer and promotes heat transfer, which increases the pressure loss during fluid flow and inevitably increases the pump load.

Therefore, an object of the present invention is to increase the mounting density of the spiral plate relative to the heat transfer area, and at the same time, reduce the pressure loss of the fluid without significantly reducing the heat transfer promotion performance, thereby reducing the pump load. It is an object of the present invention to provide a heat transfer accelerator.

(Means for Solving the Problems) In order to achieve the above object, the heat transfer accelerator according to the present invention extends the entire center of a long plate having the same width as the inner diameter of the heat transfer tube by a predetermined diameter. It is characterized by consisting of a spiral plate with continuous notches.

(Example) An example of the present invention will be described below based on the drawings.

Referring to FIG. 1, water is added to the heat exchanger tube 1 of the heat exchanger.
Fluid such as air is flowing. In this embodiment, the heat exchanger tube 1 is heated from the outside as shown by arrow Q.

A heat transfer accelerator 2 is installed inside the heat transfer tube 1,
The heat transfer accelerator 2 of the present invention has a spiral plate structure in which the entire center portion 3 of the known spiral plate shown in FIG. 3 is continuously cut out by a predetermined diameter over the entire length. There is.

In the heat transfer accelerating device 2 made of a spiral plate with the entire center portion 3 cut out, the pressure loss of the fluid can be reduced without significantly reducing the heat transfer accelerating performance. The reason for this is as follows.

In order to promote heat transfer, it is important to disturb the boundary layer near the inner surface 5 of the heat exchanger tube 1 to make the boundary layer thinner. The center portion 3 of the spiral plate in the conventional heat transfer accelerator 2 shown in FIG. 1 only swirls the fluid flowing through the center portion of the heat transfer tube 1, and only within a small range. On the other hand, the peripheral part 4 of the spiral plate swirls the fluid flowing near the inner surface 5 of the heat exchanger tube 1 and disturbs the boundary layer near the inner surface 5 of the heat exchanger tube 1, so the range of the swirl is also large. Moreover, the flow velocity of the swirling flow is also high. As mentioned above, in order to promote heat transfer, it is sufficient to disturb the boundary layer near the inner surface 5 of the heat transfer tube 1 and make the boundary layer thinner, so that the swirling flow that mainly contributes to the promotion of heat transfer is generated in the surrounding area 4. The swirling flow caused by the central portion 3 of the spiral plate does not contribute much to the promotion of heat transfer. Therefore, as shown in FIG. 1, even if the heat transfer accelerating device 2 is made by cutting out the central portion 3 of the spiral plate by a predetermined diameter, the heat transfer performance will not deteriorate significantly.

On the other hand, the center part 3 of the spiral plate is cut out to form a peripheral part 4.
It is clear that if it is made of a single material, the resistance of the fluid will be reduced and the pressure loss will be reduced.

In addition, compared to the heat transfer tube known in the above-mentioned Japanese Utility Model Publication No. 13761/1976, in which the inner periphery of the heat transfer tube is attached to the inner circumference of the heat transfer tube by twisting one small-width long plate into a spiral shape, the mounting density of the spiral plate for a given heat transfer area is lower. is doubled, and the heat transfer promoting effect is increased.

Next, the desirable width W of the spiral plate in the heat transfer accelerator 2 will be described.

FIG. ₂ shows the ratio D/
The horizontal axis represents the size of D ₀ , and the vertical axis represents a characteristic curve showing how the pressure loss and heat transfer amount of the fluid change depending on the size of the diameter D.

As the diameter D of the empty part increases,
Pressure loss becomes smaller. On the other hand, the amount of heat transfer does not change until the diameter of the vacant part reaches a certain size P, but when it exceeds P (that is, when the width W of the spiral plate becomes narrower than a certain value), heat transfer is accelerated. There is less effective swirling flow and heat transfer flow is reduced.

Therefore, when the vacant portion of the spiral plate is P, the amount of heat transfer does not decrease and the pressure loss is small. The width W of the spiral plate corresponding to this P is a desirable width.

The following is an example of a manufacturing process in which the spiral plate is installed so that it remains only at the periphery, as in the present invention.

As with the conventional method, a long plate of the same diameter is twisted and installed in advance, and then a hole is drilled in the center.

(Effect of the invention) According to the present invention, the following effects are achieved.

That is, since the heat transfer accelerating device of the present invention lacks the center portion of the spiral plate, the pressure loss of the fluid can be reduced without significantly reducing the heat transfer accelerating performance. For this reason, the size of the feed pump,
It is possible to obtain a high-performance heat exchanger system with reduced weight, reduced noise due to fluid flow, and reduced weight of heat transfer tubes.

In addition, compared to one in which a single narrow long plate is twisted spirally and attached to the inner peripheral surface of a steel heat tube, the mounting density of the spiral plate is higher for a given heat transfer area, and the heat transfer efficiency is increased accordingly. becomes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of the present invention.
FIG. 2 is a characteristic curve of the device of FIG. Third
The figure is a sectional view of the prior art. 1: Heat transfer tube, 2: Heat transfer accelerator, 3: Center part,
4: Surrounding area.

Claims (1)

[Claims] 1. A spiral plate installed in a heat transfer tube of a heat exchanger, consisting of a twisted long plate with the same diameter as the inner diameter of the heat transfer tube, and which transforms the flow of fluid in the heat transfer tube into a swirling flow. A heat transfer promoting device characterized in that the entire central portion of the spiral plate is continuously cut out by a predetermined diameter over the entire length.