JPH01148327A - Dehumidifier - Google Patents

Abstract

PURPOSE:To obtain the dehumidifier which condenses and removes the water vapor in the air at the normal temp. by combining a 1st electrochemical cell constituted by integrating an oxygen generating electrode, a hydrogen generating electrode and cation exchanging membranes with a hydrogen-air fuel cell. CONSTITUTION:An anode 2 and a cathode 2' effective to generate oxygen and hydrogen, and a positive electrode 3 and a negative electrode 3' effective for absorption are respectively disposed on both surface of the cation exchange membranes 1, 1' to be integrally connected. An anode current collector 5 is disposed between the cathode 2' and the negative electrode 3' to connect each other in a hermetical common space. The positive electrode 3 and the negative electrode 3' are short-circuited. A direct current voltage is impressed between the anode 2 and the cathode 2', and the air to be dehumidified is brought into contact with the anode. Then, the water vapor in the air is absorbed by the cation exchange membrane 1 and oxygen is generated at the anode 2 and the hydrogen is generated at the cathode 2'. The hydrogen is changed at the negative electrode 3': 2H2 4H<+>+4e<->; and at the positive electrode 3: O2+4H<+>+4e<-> 2H2O. The generated water drops are collected through a drain opening 12, and the dehumidified air is discharged from a dehumidified air discharge opening 13.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a dehumidifier using an electrochemical method.

Conventional technology Conventional dehumidification methods can be roughly divided into two: condensation methods, which lower the temperature below the dew point to condense water vapor in air or other gases, and then heat them to return to the original temperature; It can be classified into two types: adsorption methods, in which water vapor is adsorbed onto a chemical agent.

Problems to be Solved by the Invention The condensation method requires a heat exchanger for both cooling and heating operations, making it difficult to downsize and resulting in a large dehumidifier for indoor use. Furthermore, the noise generated by compressors and the like used for the purpose of vaporizing and condensing the heat medium is also large. Additionally, a method using a cooling/heating element that applies the Beltier effect is known for dehumidifying relatively small volumes inside power distribution panels, control panels, and other electrical equipment, but this method requires heat absorption and dissipation fins (heat sinks). Even if the amount of dehumidification is small, the volume and weight will be relatively large.

On the other hand, the adsorption method requires time to regenerate the desiccant, and
It is not suitable for dehumidifying living spaces or manufacturing sites for various electrical components such as semiconductors, as there is a high possibility that fine desiccant powder will be mixed into the dehumidified air.

Means for Solving the Problems The present invention is based on a cation exchange membrane-electrode assembly in which an anode as an oxygen generating electrode is integrally bonded to one side of a cation exchange membrane, and a cathode as a hydrogen generating electrode is integrally bonded to the other side. A DC voltage is applied between the positive and negative electrodes of the first electrochemical cell, supplying air to be dehumidified to the anode, electrolyzing the moisture in the air to be absorbed by the cation exchange membrane, and converting it into oxygen at the anode. Hydrogen is generated at the cathode, and a positive electrode that causes an electrolytic reduction reaction of oxygen in the air on one side of a cation exchange membrane different from the above, and a negative electrode that causes an electrolytic oxidation reaction of hydrogen on the other side are integrated. supplying hydrogen generated at the cathode of the first electrochemical cell to the negative electrode of a second electrochemical cell, i.e., a hydrogen-air fuel cell, comprising the bonded cation exchange membrane-electrode assembly; To provide a dehumidifier that collects water vapor in the air as liquid water or discharges it out of the system by supplying air to a positive electrode and short-circuiting between the positive and negative electrodes to generate water on the positive electrode side. It solves all the problems of conventional dehumidifiers at once.

Function: When the air to be dehumidified is brought into contact with the anode of the three-layer assembly, which has an anode and a cathode, each consisting of a catalytic electrode effective for generating oxygen and hydrogen, bonded together on both surfaces of a cation exchange membrane, Water vapor in the air is absorbed by the cation exchange membrane. When water is absorbed into the cation exchange membrane, the membrane acts as a solid electrolyte and becomes an electrochemical cell. When a DC voltage is applied between the anode and cathode of this cell, at a certain voltage or higher, the anode changes as follows: 2H20 → 02 + 4H" +48- (1)
Oxygen is generated by the reaction, and 4H" +4e at the cathode.
--42H2(2) Hydrogen is produced by the reaction. This reaction is a water electrolysis reaction of water vapor in the air, and when a constant voltage is applied, an electrolytic current proportional to the relative humidity flows, and the higher the humidity, the more
Dehumidification occurs promptly.

However, even though it has a dehumidifying effect, oxygen and hydrogen are generated at both electrodes, so if it is directly released into a certain space to be dehumidified, it is not preferable in terms of corrosion and safety.

Therefore, a method of oxidizing the generated hydrogen by passing it through a catalyst-packed column or the like may be considered, but this would require a complicated structure to completely remove the hydrogen, and the overall size of the device would also increase.

The present invention relates to a novel device for oxidizing this hydrogen to produce water. That is, the aforementioned cation exchange f
! j! Hydrogen produced at the membrane cathode is supplied to one side of a separate cation exchange membrane-electrode assembly, and air as an oxygen source is supplied to the other side. This assembly has a three-layer structure in which catalytic electrodes effective for absorbing hydrogen and oxygen are integrally bonded to both sides of a cation exchange membrane. When the picture electrode is short-circuited, the cation exchange membrane functions as a solid electrolyte, with the hydrogen supply side serving as the negative electrode and the oxygen supply side serving as the positive electrode.
A so-called fuel cell is constructed. In other words, hydrogen is consumed at the negative electrode by the reaction 2H2448" +4e-(3), and at the positive electrode 02 +
48” +4e −+ 2820 (4) Water is produced by the reaction.The water produced at the positive electrode is not in the form of water vapor, but in liquid form and leaks out as water droplets on the back of the positive electrode.Thus, the gas It becomes possible to collect water as liquid water.

As described above, the dehumidifier according to the present invention generates oxygen and hydrogen from water vapor in the air in the first stage, and oxidizes the generated hydrogen with oxygen in the second stage to turn it into water.

Dehumidification is performed by collecting or discharging the water from the system. In the dehumidifier of the present invention, oxygen is generated in the first stage, but the same amount of oxygen is consumed in the second stage, so the oxygen balance of the entire system is zero.

The anode and cathode effective for the electrolytic reactions (1) and (2) of water vapor in the air may be the same catalytic electrode. Touching the cation exchange membrane a There is a method of pressurizing and integrating the mixture with the agent by hot pressing.

In addition, the negative and positive electrodes that are effective for the water production reactions (3) and (4) can be the same catalyst electrode, but they are slightly different from the electrodes for water electrolysis mentioned above, and are generally called gas diffusion electrodes. It is. For example, a mixture of a platinum group metal or carbon supporting a platinum group metal and a fluororesin binder, or a mixture of these and a cation exchange resin is hot-pressed into a cation exchange membrane. Things are good.

Embodiment FIG. 1 is a schematic diagram of a dehumidifier according to one practical example of the present invention.

Cation exchange membrane made of perfluorocarbon sulfonic acid resin 1. Electrodes 2.2' effective for generating oxygen and hydrogen, and electrodes 3.3' effective for absorption are integrally joined to the lower surfaces. The anode 2 and the cathode 2' are made of platinum,
It is bonded to the cation exchange membrane 1 by electroless plating. The positive electrode 3 and the negative electrode 3' are made of a mixture of carbon powder supporting a platinum catalyst, an aqueous suspension of polytetrafluoroethylene, and a perfluorocarbon sulfonic acid resin solution using a lower aliphatic alcohol as a solvent. It is constructed by joining both sides under the exchange membrane using a hot press method.

On the back side of the anode/cathode 2.2' are an anode current collector 4 and a cathode current collector 5 made of expanded titanium plated with platinum.
are respectively arranged, and these current collectors are connected to a DC power source (not shown) through an anode terminal 6 and a cathode terminal 7. A positive i-bundle current body 8 made of expanded titanium plated with platinum is also disposed on the back side of the positive electrode 3.
Since the aforementioned cathode current collector 5 is disposed on the back surface of the negative electrode 3', what is called a negative electrode current collector is not necessary. This cathode current collector 5 is connected (short-circuited) to a positive electrode current collector 8 via a cathode terminal 7 and a positive electrode terminal 9. Cathode 2' and negative electrode 3'
The cathode current collector 5 is disposed between the cathode 2
A certain closed space is formed to prevent the hydrogen generated in ' from escaping.

The electrochemical cell group configured in this manner is housed in a case 10. The case 10 includes an air intake port 11 and a drain port 12 for water droplets generated by dehumidification, and the dehumidified air is discharged from a dehumidified air discharge port 13 into a target space by a blower 14. The air flow inside this dehumidifier is such that it first oxidizes hydrogen to generate and collect water, and then dehumidifies the air. A structure in which the generation section is separated or a multi-cell structure can also be used.

In the dehumidifier of the present invention, the electrode areas of the anode/cathode 2.2' and the cathode 3 are set to 100-, a constant DC voltage of 3V is applied between the anode and cathode terminals 6.7, and the volume is 20ft (30℃). When water vapor saturated air was dehumidified, the second rj! As shown in i (we were able to dehumidify to a relative humidity of 30%. Note that if the purpose is only to prevent condensation, it is sufficient to dehumidify until the relative humidity is around 90%, so the electrode area is the same as that of this example. A value of about 115 is sufficient, and the dimensions can be further reduced.

Effects of the Invention The present invention can condense water vapor in the air at room temperature, makes no noise, can be configured with dimensions suitable for a small dehumidifying space, and can be regenerated. Clean dehumidified air can be obtained without any need for dehumidification, and automatic control is easy using an electrochemical dehumidification method, so its industrial value is extremely high.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the dehumidifier of the present invention;
FIG. 2 is a diagram showing changes in relative humidity caused by the dehumidifier of the present invention. 1. Cation exchange membrane 2...Anode 2'...Cathode 3...Positive electrode 3'...Negative electrode 11... ... Air intake port 12 ... Drain port 13 ... Dehumidifying air discharge port
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Claims (1)

[Claims] A cation exchange membrane with an anode as an oxygen generation electrode on one side and a cathode as a hydrogen generation electrode on the other side is integrally bonded to a case equipped with an air intake, a dehumidified air outlet, and a drain. A first electrochemical cell consisting of an exchange membrane-electrode assembly, a positive electrode for causing an electrolytic reduction reaction of atmospheric oxygen on one side of the cation exchange membrane, and a negative electrode for causing an electrolytic oxidation reaction of hydrogen on the other side. A second electrochemical cell consisting of an integrally bonded cation exchange membrane-electrode assembly is disposed, and the cathode of the first electrochemical cell and the negative electrode of the second electrochemical cell are connected through a sealed common space. A dehumidifier characterized in that the dehumidifier is configured to short-circuit the positive and negative electrodes of the second electrochemical cell and apply a DC voltage between the positive and negative electrodes of the first electrochemical cell.