JPS5941118B2 - liquid attracting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a device in which high-voltage electrodes are placed opposite a liquid surface to draw a liquid interface to the electrodes, and more particularly to optimization of the electrodes in the liquid drawing device.

An important aspect of promoting energy conservation is the recovery of low-temperature waste heat.

For example, 60% of the total amount of heat discarded in major factories is low-temperature waste heat, and by recovering this waste heat, it is possible to regenerate a large amount of energy.

However, a major obstacle when recovering low-temperature waste heat is the increasing size of the condensing heat exchanger.

In other words, when adopting a thermal cycle using low-temperature waste heat,
To obtain the same output as normal thermal power generation, 10 times the condensing heat transfer surface is required.

This may not be viable in terms of cost.

The present inventors have been considering improving the heat exchange rate on the condensation heat transfer surface, and have discovered that a high voltage electrode has the effect of drawing the liquid interface together, and have already filed a patent application for this.

(Unexamined Japanese Patent Publication No. 1983-42096) In this existing application, the liquid condensed on the heat transfer surface is drawn to the high voltage electrode and discharged, thereby reducing the thickness of the liquid film on the heat transfer surface and improving the heat exchange efficiency. That is.

However, the previous application only discovered the fact that high-voltage electrodes attract liquid, and the theoretical explanation was still insufficient.

Therefore, we conducted a theoretical analysis assuming that the liquid attraction effect is the occurrence of instability at the gas-liquid interface in an unequal electric field, followed by a liquid attraction phenomenon due to the unequal electric field, and compared this with experimental results. The theoretical analysis value and experimental value agreed.

Regarding this theoretical analysis and experiment, please refer to the Proceedings of the 18th Japan Heat Transfer Symposium (1972) attached to this patent application.
(June 23rd to June 25th, 2015, Sendai City) as shown in the preliminary draft.

As a result, it was found that the liquid-attracting effect of the high-voltage electrode holds true theoretically.

Now, although the existing application was based on a condensing type heat exchanger, it is obvious to those skilled in the art that the liquid drawing effect by high voltage electrodes can be used in various industrial fields other than the field of heat exchangers. That's understandable.

An object of the present invention is to seek optimization of electrodes when actually implementing the liquid attracting effect using high voltage electrodes.

Although only a small amount of power is consumed when drawing liquid with a high-voltage electrode, achieving the liquid drawing effect with an even lower voltage is an important issue in terms of power consumption and safety of practical devices.

In previous applications, this has been done using a needle electrode and a single wire electrode extending in the direction of gravity, but subsequent research has clarified a more effective electrode configuration.

In the present invention, in researching desirable electrodes, an experimental apparatus as shown in FIG. 1 was used.

Freon R113 circulates in a closed manner between the condensing section 1 and the boiling section 2.

A heat transfer surface 3 is provided inside the condensing section 1 .

One surface of the heat transfer surface 3 is exposed to Freon R113, and the other surface is in contact with cooling water.

Cooling water is sent from inside the tank 4 to the heat transfer surface 3 via the pump 5.

A heater 6 is provided in the boiling part 2, and a Freon R113
evaporate.

An electrode 7 is provided opposite the heat transfer surface 3 and is positively charged by a high voltage generator 8.

The high voltage generator 8 is on the other hand connected to the heat transfer surface 3 and charges the heat transfer surface 3 negatively.

Below the heat transfer 3 and electrode 1 are female cylinders 9 and 10, respectively.
are provided, and the reservoirs are drained by means of electromagnetic valves 11 and 12, respectively.

An enlarged view of the heat transfer surface 3 and the electrodes 7 is shown in FIG.

The electrode holder 13 made of an insulating material such as acrylic is provided with a liquid extraction hole 14 obliquely, and the electrode 1 is fixed above the opening 141 of the extraction hole 14 facing the heat transfer surface 3 .

FIG. 3 shows the results of a comparative experiment between one wire electrode and two wire electrodes, with the vertical axis representing the attraction effect generating voltage ψ (KV) and the electrode spacing D (mm) representing the horizontal axis.

Here, the electrode spacing is the spacing between the heat transfer surface 3 and the electrodes 7.

The characteristics of one wire electrode are as shown by △, the electrode spacing is 3mm.
Up to this point, the characteristics of the two wire electrodes are higher than the values indicated by ○.

Note that no attracting effect occurred with three wire electrodes in which the distance between each electrode was 1 mm.

From the above, it has been found that it is desirable to provide two wire electrodes in order to obtain an attracting effect in a relatively low high voltage range.

FIG. 4 is a characteristic diagram showing the relationship between the distance W (no) between the two wire electrodes and the attraction effect generating voltage ψt (KV).

As can be seen from the figure, when the distance W is around 1 mm, the voltage at which the attracting effect occurs is minimum.

From the above explanation, D = the practical range of electrode spacing
It has been found that at 2.5no or less, two wire electrodes always require a lower voltage, and it is desirable to extend the wire electrodes in parallel so that the distance between the wire electrodes is about 1 mm.

As described above, according to the present invention, it is possible to use as low a high voltage as possible, thereby achieving a further reduction in power consumption, and at the same time, it is possible to improve the safety and reliability of the device.

Note that the present invention can be used in various industrial fields in addition to reducing the thickness of the liquid film on the heat transfer surface of a condensing heat exchanger, and is not limited to the above embodiments.

For example, it is well understood by those skilled in the art that a flow path can be selected using a high-voltage electrode in a fluid device, and that the present invention can also be applied to the fields of inspection and measurement.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the experimental apparatus according to the present invention, Figure 2 is a characteristic diagram showing the number of wire electrodes and the voltage at which the attraction effect occurs, and Figure 3 is the distance between the two wire electrodes and the voltage at which the attraction effect occurs. FIG. 4 is a characteristic diagram showing the distance between two wire electrodes and the voltage at which the attracting effect occurs.

Claims (1)

[Claims] 1. In a device in which a high-voltage electrode is installed on the liquid surface and the liquid is drawn to the electrode by the occurrence of instability at the liquid interface and an uneven electric field, the electrodes are two wire electrodes extending in parallel. Features a liquid attracting device.