JPH0634899B2 - Water vapor selective permeable membrane - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water vapor selective permeable membrane used for separating water from the air in a dehumidifier or the like.

(Problems to be Solved by the Related Art and Invention) Generally, in an outdoor unit of an air conditioner, when air containing a certain amount of humidity is supplied during heating operation in a low temperature environment, the air of the outdoor unit Frost is generated on the heat exchanger, and a defrosting operation for removing the frost is required. As a result, there is a problem that it is difficult to avoid the reduction of the air conditioning capacity, and it is said that the lower the humidity of the air supplied to the outdoor unit, the more preferable.

On the other hand, as a method of dehumidifying air, a method of cooling the air below a dew point using a cooling device to dehumidify, or a method using a hygroscopic agent such as silica gel is generally used. There is a problem that it is difficult to use for the above-mentioned applications because it requires heating for regenerating the agent. Further, as disclosed in Japanese Patent Application Laid-Open No. 62-117613, a method of dehumidifying using a gas separation membrane has already been proposed. There is a problem that it requires a large amount of power for.

The present invention has been made in view of the above points, and does not provide a water vapor selective permeable membrane capable of effectively separating and removing water from the air at a relatively low pressure level.

(Means for Solving the Problems) In the present invention, as means for solving the above problems, as shown in FIG. 1, water mixed in the air is selectively adsorbed and is not combined with the adsorbed water. First layer film member 11 made of a water-absorbing porous film material, and H ₂ O / N ₂ and H ₂ O /
And a second layer film member 12 made of a film material having a large O ₂ transmission coefficient ratio and a large H ₂ O transmission coefficient absolute value,
A third layer film member 13 made of a conductive porous material is further laminated on the second layer film member 12. Instead of the third layer film member 13, or the third layer film member 13
There is also a case where the reinforcing member 14 having high physical strength is laminated.

(Operation) In the present invention, the following effects can be obtained by the above means.

That is, when the high-humidity air F ₁ is circulated to the first-layer film member 11 side while maintaining a pressure slightly higher than the atmospheric pressure, the water contained in the high-humidity air F ₁ is adsorbed to the first-layer film member 11, The water concentration of the one-layer film member 11 becomes high. Thus, the second
When the water concentration on the surface of the layer film member 12 on the first layer film member 11 side is increased, the water concentration on both sides of the second layer film member 12 is increased, and the permeation that passes through the second layer film member 12 even with a small pressure difference It is possible to increase the water content sufficiently. Further, since the third layer film member 13 made of a conductive porous material is laminated on the second layer film member 12, the temperature of the high humidity air F ₁ is low and the first layer film member 1
When water is likely to freeze in the first and second layer film members 12, the film temperature can be raised to the freezing point or higher by the heat generated by energizing the third layer film member 13, and water vapor can be secured. Of. Further, instead of the third layer membrane member 13 or by laminating a reinforcing member 14 having high physical strength with respect to the third layer membrane member 13, the rigidity of the water vapor selective permeable membrane can be enhanced. Therefore, the scope of application will be greatly expanded.

(Examples) Hereinafter, preferred examples of the present invention will be described with reference to the accompanying drawings.

The water vapor selective permeable membrane 1 of the present embodiment includes a first layer membrane member 11 made of a water-absorbing porous membrane material that selectively adsorbs moisture mixed in air, and H ₂ O / N ₂ and H ₂ O /. A second layer film member 12 made of a film material having a large O ₂ permeation coefficient ratio and a large absolute value of H ₂ O permeation coefficient, a third layer film member 13 made of a conductive porous material, and a porous material. And a reinforcing member 14 for maintaining strength, which are formed by laminating.

As the first layer film member 11, water mixed in the air
Material that has the effect of selectively adsorbing (that is, water vapor)
(That is, a polymer having a hydrophilic group, etc.) and in the thickness direction of the film
A diameter (for example, 1.0 μm) larger than the free path (that is, 0.5 μm) of the water vapor molecules so that the water vapor molecules can sufficiently penetrate deep inside (that is, the one in contact with the second layer film member 12).
A membrane with a porous structure having a communication hole of 0.5 mm) is desirable. As a specific example, a membrane made of a polyvinyl alcohol porous body, a membrane made of a hydrophilic acrylonitrile copolymer made porous, a membrane made of gel cellophane, and a water-absorbing gel were retained. For example, non-woven fabric. Further, it is desirable that the thickness of the first layer film member 11 is appropriately selected within a range of 0.1 to several μm. It should be noted that a material (for example, a silica gel sheet) that binds to the adsorbed water and makes it difficult for the water to separate even if the water has a strong adsorbing power is inappropriate.

As described above, the second layer film member 12 has a large ratio of the permeability coefficient of water H ₂ O to the permeability coefficients of nitrogen N ₂ and oxygen O ₂ in the air (that is, the permeability coefficient ratio), and the water H ₂ A membrane material having a large absolute value of the permeability coefficient of is preferable, and specific examples thereof include a cellulose acetate membrane, a 3 cellulose acetate membrane,
Examples thereof include a film made of a copolymer of polybutadiene and acrylonitrile, and an ethyl cellulose film.

The reason for selecting the material as described above is based on the following facts.

That is, 98% of the composition of air, since it is N ₂ and O _2, The use of large permselective membrane permeability coefficient ratio of the H ₂ O / N ₂ and _{H 2 O / O 2, N} 2 , O ₂ transmission is low, and H ₂
O becomes easy to permeate, but to the contrary, H ₂ O / N ₂ and H ₂
Even permeability coefficient ratio of O / O ₂ is greater, the absolute value of the transmission coefficient H ₂ O is small, resistance is increased when the H ₂ O is transmitted through the film will have to increase the membrane area Because. By the way, in the case of cellulose acetate, H ₂ O / N ₂
Transmission coefficient ratio ≈ 17,000, H ₂ O / O ₂ transmission coefficient ratio ≈ 850
0, H ₂ O transmission coefficient ≈ 6800 × 10 ^-10 cm ³ · cm / cm ² · sec · cmH
g, similarly in the case of polybutadiene-acrylonitrile copolymer, H ₂ O / N ₂ permeation coefficient ratio ≈ 58000, H ₂ O
/ O ₂ transmission coefficient ratio ≈ 15000, H ₂ O transmission coefficient ≈ 24600 ×
It has desirable characteristics such as 10 ^-10 cm ³ · cm / cm ² · sec · cmHg. Of course, other materials also have similar characteristics.

As the third layer film member 13, a member formed by embedding a conductive member in a porous film material that allows water to permeate is adopted, and can act as a heating element by energizing the conductive member. Is configured. That is, the environment in which the water vapor selective permeable membrane according to the present embodiment is used is at a low temperature (that is,
When the temperature is below the freezing point), the third layer film member 13 is made to act as a heating element by energizing the conductive member so that the permeated water is prevented from freezing. Since it is necessary to allow the water vapor that has permeated the second membrane layer member 12 to permeate the third layer membrane member 13 and the reinforcing member 14 with a small pressure loss, the third layer membrane member 13 and the reinforcing member 1
4 is a porous material having a communication hole having a pore diameter of 5 μm or more. As the reinforcing member 14, various materials (for example, metal, ceramics, polymer, paper, etc.) can be used as long as they are porous materials that allow water to permeate and maintain a certain level of strength.

Furthermore, depending on the environment of use, etc., the third layer film member 13
In some cases, the reinforcing member 14 may be laminated on the second layer film member 12 in place of the third layer film member 13 and the reinforcing member 14.
May be omitted.

The water vapor selective permeable membrane having the above-described structure operates as follows.

High humidity air F ₁ having a pressure higher than atmospheric pressure by 10 to 100 mmH ₂ O on the side of the first layer membrane member 11 of the water vapor selective permeable membrane ₁
While allowing the water to flow, the reinforcing member 14 of the water vapor selective permeable membrane 1
When the atmosphere F ₂ is circulated to the side, moisture (that is, water vapor) contained in the high-humidity air F ₁ is selectively adsorbed on the first layer film member 11, and the water vapor concentration on the surface of the second layer film member 12 is increased. It will be raised. Therefore, even if the pressure difference between the both surfaces of the water vapor selective permeable membrane 1 is not so high, the selective permeation of water through the second layer membrane member 12 can be carried out quickly. Therefore, the high-humidity air F ₁ flowing through the first layer film member 11 side is dehumidified and approaches dry air, while the atmosphere F ₂ flowing through the reinforcing member 14 side becomes air with increased humidity.

When the high-humidity air F ₁ has a low temperature below the freezing point, water vapor may freeze in the first and second layer film members 11 and 12, but in that case, the third layer film member The water vapor temperature is kept above the freezing point by the heat obtained by energizing 13 and causing it to act as a heating element.

Next, a specific example of the dehumidifying device using the water vapor selective permeable membrane 1 according to the present embodiment will be described with reference to FIGS. 2 and 3.

The dehumidifying device A of this embodiment is applied to the air conditioner shown in the refrigerant circuit diagram of FIG.

The refrigerant circuit of this air conditioner is configured by sequentially connecting a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an expansion mechanism 24, and an indoor heat exchanger 25. The four-way switching valve 22 performs a switching operation. By reversibly circulating the refrigerant in the direction of the solid arrow or the dotted arrow, the cooling or heating operation is performed. In order to dehumidify the outside air supplied to the outdoor heat exchanger 23, the dehumidifying device A is installed in the first outside airflow passage 26 through which the air F ₁ on the steam releasing side flows. Reference numeral 27 indicates humidity (in other words, humidity)
A second outdoor airflow passage through which the air F ₂ on the side of receiving (water vapor) flows, 28 is an outdoor fan, and 29 is an indoor fan.

As shown in FIG. 2, the dehumidifying apparatus A is formed by alternately laminating a plurality of water vapor selective permeable membranes 1, 1, ... And a plurality of spacing plates 2, 2 ,. The water vapor permselective membranes 1, 1, ...
The corrugated molding directions are alternately sandwiched by 90 ° and sandwiched between them. Then, between the water vapor selective permeable membranes 1, 1 ... And the spacing plates 2, 2 ...
Primary ventilation passages 3, 3 ... And secondary ventilation passages 4, 4 .. Reference numeral 5 is a lid plate that closes the upper surface and the lower surface of the dehumidifier A.

The dehumidifier A is installed so that the primary ventilation passages 3, 3, ... Face the first external airflow passage 26 and the secondary ventilation passages 4, 4 ,. In addition, in the water vapor selective permeable membrane 1, the side of the first layer membrane member 11 is the primary ventilation passage 3, 3, ...
It will be installed on the side.

The dehumidifying device having the above structure operates as follows.

The outside air (that is, the outside air flowing through the first outside airflow passage 26)
(High-humidity air) F ₁ is a water vapor selective permeable membrane 1, ₁ while the moisture contained in the outside air F ₁ passes through the primary ventilation passages 3, 3.
· Dehumidified by being transmitted to the secondary air passage 4,4 ... side through the outdoor heat exchanger becomes dehumidified air F ₃ unit 2
3 is supplied. On the other hand, the air F ₂ circulated in the second outside airflow passage 27 obtains water vapor which is transmitted from the primary ventilation passages 3, 3 ... Side while passing through the secondary ventilation passages 4, 4 ,. Is discharged as the exhaust air F ₄ . Therefore, since the air supplied to the outdoor heat exchanger 23, which functions as an evaporator during the heating operation, is in a dry state where the humidity level is below a predetermined value, the air conditioner in a low temperature state is During operation, there is no possibility of frost formation, and it is possible to carry out substantially no frost operation.

(Advantages of the Invention) As described above, the present invention comprises a first layer membrane member 11 made of a water-absorbing porous membrane material that selectively adsorbs moisture mixed in air and does not combine with the adsorbed water. ₂ O / N ₂ and H ₂
Since the second layer membrane member 12 made of a membrane material having a large O / O ₂ permeation coefficient ratio and a large absolute value of H ₂ O permeation coefficient is laminated to form a water vapor selective permeable membrane.
The high-humidity air F ₁ is circulated to the first layer film member 11 side, while the air F to receive water vapor to the second layer film member 12 side.
_{When 2} is circulated, the moisture contained in the high-humidity air F ₁ becomes the first
By being adsorbed by the layer film member 11, the moisture concentration on the surface of the second layer film member 12 increases, so that the high humidity air F
_{Even if} the pressure difference between ₁ and the air F ₂ is not so high, the amount of water permeated through the second layer film member 12 can be sufficiently increased, which is an excellent effect.

Further, according to the present invention, since the third layer film member 13 made of a conductive porous material is laminated on the second layer film member 12, the temperature of the high humidity air F ₁ is low, Even if water may freeze in the first-layer film member 11 and the second-layer film member 12, the third-layer film member 13
The film temperature can be raised to the freezing point or higher by the heat generated by energizing the device, and the effect that the water vapor can be secured is obtained.

Further, as in claims 2 and 3, instead of the third layer film member 13, or if a reinforcing member 14 having high physical strength is laminated on the third layer film member 13, the steam selection can be performed. By strengthening the rigidity of the permeable membrane,
The effect is that the scope of application can be greatly expanded.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a water vapor selective permeable membrane according to an embodiment of the present invention, FIG. 2 is a perspective view showing a dehumidifier using the water vapor selective permeable membrane according to an embodiment of the present invention, and FIG. It is a refrigerant circuit diagram of the air conditioner which is an example of use of the dehumidification device shown in the figure. 1 ... Water vapor selective permeable membrane 11 ... First layer membrane member 12 ... Second layer membrane member 13 ... Third layer membrane member 14 ... Reinforcing member

Claims (3)

[Claims] 1. A first layer membrane member (11) made of a water-absorbing porous membrane material for selectively adsorbing moisture mixed in air,
A _second film made of a film material having a large transmission coefficient ratio of H ₂ O / N ₂ and H ₂ O / O ₂ and a large absolute value of the transmission coefficient of H ₂ O.
A third layer film member (13) laminated with the layer film member (12) and further made of a conductive porous material with respect to the second layer film member (12).
A water vapor selective permeable membrane, characterized in that 2. A first layer membrane member (11) made of a water-absorbing porous membrane material for selectively adsorbing water mixed in air,
A _second film made of a film material having a large transmission coefficient ratio of H ₂ O / N ₂ and H ₂ O / O ₂ and a large absolute value of the transmission coefficient of H ₂ O.
Water vapor selection characterized in that a layer film member (12) is laminated, and a reinforcing member (14) made of a porous material having a higher physical strength is laminated to the second layer film member (12). Permeable membrane. 3. The steam selection according to claim 1, further comprising a reinforcing member (14) made of a porous material having high physical strength, which is further laminated on the third layer film member (13). Permeable membrane.