JPH023917B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of promoting heat transfer using an electric field in a heat exchanger that boils a heat medium flowing through a pipe.

(Prior art) Freon flowing through the pipe due to heat from outside the pipe,
There is a heat exchanger that transfers heat by boiling a heat medium such as water.

Referring to Fig. 3, this heat exchanger (not shown)
The figure shows how the heat medium 2 inside the pipe line 1 changes when it receives heat Q from outside the pipe line 1. The heat medium in the liquid 2 state receives the heat Q and boils.

At the beginning of conduit 1, gas 3 forms bubbles in liquid 2.
A two-phase flow occurs in the area (A region). In the next stage, gas 3 flows near the center of pipe 1, and liquid 2
becomes an annular flow that flows in an annular manner near the inner wall surface 4 of the conduit 1 (region B). The liquid 2 then becomes a spray stream (region C). Finally, all of the liquid 2 is vaporized and becomes vapor 5 (region D).

After leaving the heat exchanger, this steam 5 is sent to a power generation turbine or the like.

(Problem to be Solved by the Invention) However, in the spray flow in region C in the above state, the fine droplets 6 are uniformly present throughout the pipe 1, so the heat Q from outside the pipe 1 is D is difficult to transmit to the fine droplets 6 and completely vaporizes into vapor.
It was taking a long time to reach the area. Therefore, a long pipe line 1 from the spray flow area C to the steam D area is required, which is one of the reasons for hindering the miniaturization of the heat exchanger.

An object of the present invention is to shorten the pipe line 1 in the region where the spray flow becomes steam by promoting heat transfer in the spray flow in the C region, thereby downsizing the heat exchanger.

(Means for Solving the Problems) In order to achieve the above object, the present invention promotes heat transfer of the spray stream as follows.

A mesh electrode surrounding the center of the cross section of the pipe is installed at a location in the pipe where the heat medium becomes a spray flow, and the pipe is used as one electrode, and the mesh electrode is used as the other electrode to connect the pipe and the mesh electrode. Apply high voltage between the two.

(effect) The invention works as follows.

When a high voltage is applied between the mesh electrode and the conduit, an electric field is created between the mesh electrode and the conduit. There is no electric field in the mesh electrode, that is, in the center of the conduit 1, and gas collects there. This is because the gas is subjected to a force that causes it to be ejected from an area where the electric field is strong to an area where the electric field is weak.

On the other hand, droplets with a higher dielectric constant than gas are subjected to a force that draws them from an area with a weak electric field to an area with a strong electric field, so the fine droplets gather near the inner wall surface of the conduit. Therefore, the fine droplets receive heat from outside the conduit and are easily vaporized.

(Example) An example of the present invention will be described below based on FIGS. 1 and 2. In the present embodiment, the heat exchanger (not shown) transfers heat by boiling the heat medium flowing through the pipes. FIGS. 1 and 2 show locations in the pipe line 1 that would conventionally form a spray flow (region C).

In this embodiment, a mesh electrode 11 surrounding the center of the cross section of the conduit 1 is installed. Then, a high voltage is applied between the conduit 1 and the mesh electrode 11, with the conduit 1 itself serving as one electrode and the mesh electrode 11 serving as the other electrode. 12 is a power source.

An electric field is created between the mesh electrode 11 and the conduit 1. There is no electric field within the mesh electrode 11, that is, near the center 13 of the conduit 1, and the gas 3 gathers here. This is because the gas 3 receives a force that is ejected from a place where the electric field is strong to a place where the electric field is weak.

On the other hand, the fine droplets 6 are attracted near the inner wall surface 4 of the conduit 1 because they are attracted by the stronger electric field. Therefore, the fine droplets 6 have an increased chance of coming into contact with the inner wall surface, and are more likely to receive heat from outside the pipe line 1 and vaporize.

In this way, since the spray stream turns into steam more quickly, the length of the pipe line 1 can be shortened, and the heat exchanger can be made smaller.

(Effects of the Invention) As described above, according to the present invention, heat transfer at the stage of spray flow is promoted and the spray becomes steam quickly, so the length of the pipe can be shortened and the heat exchanger can be downsized.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a pipe line of a heat exchanger according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the - line in FIG. FIG. 3 is a longitudinal cross-sectional view showing a heat medium inside a pipe. 1: pipe line, 3: gas, 4: inner wall surface of pipe line, 6:
Fine droplets, 11: Mesh electrode, C: Point where the spray flow is formed.

[Claims]

1. A wire electrode 12 is provided along the axis of the pipe 1 at the bubble flow (A) and/or annular flow (B) position in the pipe 1 where the two-phase flow is flowing, and the wire electrode 12 is placed outside the wire electrode 12. A mesh electrode 13 is provided surrounding the line electrode 12, and a high voltage is applied between the wire electrode 12 and the mesh electrode 13 to collect the gas 3 near the inner wall surface 4 of the pipe 1, and the liquid 2 near the center of the pipe 1. A method for improving the flow characteristics of a two-phase flow using an electric field, characterized in that the flow is as follows.