Preparation method of low-temperature regenerative dehumidification rotary wheel based on reversible conversion of hydrophilicity and hydrophobicity

Abstract

The application discloses a preparation method of a low-temperature regenerative dehumidification rotating wheel based on hydrophilic-hydrophobic reversible conversion and belongs to the technical field of dehumidification rotating wheel manufacturing. The application discloses a preparation method of a low-temperature regenerative dehumidification rotating wheel based on hydrophilic-hydrophobic reversible conversion and belongs to the technical field of dehumidification rotating wheel manufacturing. The application discloses a preparation method of a low-temperature regenerative dehumidification rotating wheel based on hydrophilic-hydrophobic reversible conversion and belongs to the technical field of dehumidification rotating wheel manufacturing. The application discloses a preparation method of a low-temperature regenerative dehumidification rotating wheel based on hydrophilic-hydrophobic reversible conversion and belongs to the technical field of dehumidification rotating wheel manufacturing. The application discloses a preparation method of a low-temperature regenerative dehumidification rotating wheel based on hydrophilic-hydrophobic reversible conversion and belongs to the technical field of dehumidification rotating wheel manufacturing.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of dehumidification rotary wheel manufacturing, in particular to a preparation method of a low-temperature regeneration dehumidification rotary wheel based on reversible conversion of hydrophilicity and hydrophobicity. BACKGROUND

[0002] Air humidity is one of important indexes of constant air quality, and is closely related to our production and life. Some studies show that people will become listless in an environment with excessive humidity, and if people work and live in such an environment for a long time, it will cause metabolic disorder and even physiological function diseases such as waist and leg pain and rheumatism. In daily life, excessive humidity is also easy to cause short circuit of electric wires and thus cause loss of life and property; in storage and production, excessive humidity is easy to cause printed matter, medicine, grain, seed, food and other articles to be damp and cause deterioration or mildew; in the production process of precision machinery, measuring instruments, electronics, textiles and chemical industry, excessive humidity will also seriously affect product quality. At the same time, in high humidity, fiber products such as clothes and bed sheets are also easy to be damaged, and metal objects such as steel are also easy to be corroded and seriously affect service life. Therefore, humidity control is necessary, and rotary dehumidification is a common dehumidification technology, which is commonly used in daily life and industrial production.

[0003] The dehumidification rotary wheel is the most core component of the rotary dehumidification, and its main component is a solid moisture absorbent. The dehumidification rotary wheel is divided into two areas in the dehumidification process: a treatment area and a regeneration area; when humid air needing dehumidification passes through the treatment area of the rotary wheel, the water vapor of the humid air is absorbed by the absorbent of the rotary wheel, and the dry air is sent to the space needing treatment by the fan to reduce the humidity in the space; the rotary wheel rotating slowly carries the absorbent tending to be saturated into the regeneration area; the high-temperature air blown into the regeneration area reversely makes the water absorbed in the rotary wheel be desorbed, and then is discharged to the outside by the fan, so that the rotary wheel restores the moisture absorption capacity and completes the regeneration process. The rotary wheel rotates continuously, and the above dehumidification and regeneration processes are repeated to ensure that the rotary wheel maintains a stable dehumidification state.

[0004] However, the commonly used rotary dehumidification materials such as 13X, 4A and 5A molecular sieves all have a high regeneration temperature generally between 150-200 DEG C, which makes it need to consume more energy in the regeneration process, which makes it have no obvious advantage in energy consumption compared with the traditional condensation dehumidification, and the high regeneration temperature also means that there is a great fire hazard in the use process. SUMMARY

[0005] The application aims to provide a preparation method of a low-temperature regenerative dehumidification rotating wheel based on reversible conversion of hydrophilicity and hydrophobicity, so that the prepared dehumidification rotating wheel has the characteristics of low-temperature regeneration, can effectively reduce the energy consumption in the dehumidification process of the rotating wheel, and achieves the purpose of energy saving and emission reduction; and the dehumidification rotating wheel can also well adsorb water vapor in the air at a lower temperature to achieve the purpose of air dehumidification.

[0006] To achieve the above-mentioned purpose, the application provides a preparation method of a low-temperature regenerative dehumidification rotating wheel based on reversible conversion of hydrophilicity and hydrophobicity, which comprises the following steps:

[0007] S1, pretreat the glass fiber paper with a polyvinyl alcohol aqueous solution, then press a part of the glass fiber paper into corrugated paper with a corrugating machine, and then roll the corrugated paper and another part of the glass fiber paper into a disc shape after mutual superposition and drying to obtain a blank rotating wheel;

[0008] S2, dissolve N-isopropyl acrylamide and a crosslinking agent in water and stir uniformly, then add an initiator and an accelerator to react to obtain a poly N-isopropyl acrylamide hygroscopic material;

[0009] S3, take the poly N-isopropyl acrylamide material obtained in S2, soak it in an inorganic salt solution, and then wash and dry to obtain a composite hygroscopic material based on reversible conversion of hydrophilicity and hydrophobicity;

[0010] S4, take the composite hygroscopic material obtained in S3, and fully stir polyvinyl alcohol and calcium citrate in water according to a certain proportion, and then ultrasonically disperse them uniformly to obtain a hygroscopic material-polyvinyl alcohol-calcium citrate mixed suspension;

[0011] S5, soak the blank rotating wheel prepared in S1 in the mixed suspension prepared in S4 for a period of time, blow off the residual water in the disc cavity, and then dry to obtain a low-temperature regenerative dehumidification rotating wheel based on reversible conversion of hydrophilicity and hydrophobicity after repeating 2-3 times.

[0012] Preferably, in S1, the glass fiber paper can be replaced with paper made of other high-temperature resistant materials such as ceramic fiber or other woven materials.

[0013] Preferably, in S1 and S4, the alcoholysis degree of the added polyvinyl alcohol aqueous solution is more than 95%, and the concentration is 5-10 wt%.

[0014] Preferably, in S2, 90%-95% of N-isopropyl acrylamide and 5%-10% of a crosslinking agent are added, and the crosslinking agent is N, N'-methylene bisacrylamide.

[0015] Preferably, in S2, the initiator is ammonium persulfate, and the addition amount is 5%-10% of the total mass of N-isopropyl acrylamide and the crosslinking agent.

[0016] The accelerator is N, N'-tetramethyl ethylenediamine, and the amount of addition is 80%-90% of the total mass of N-isopropyl acrylamide and crosslinking agent.

[0017] Preferably, in S2, the reaction time is 5-12h, and the reaction temperature is 0-6℃.

[0018] Preferably, in S3, the inorganic salt solution is lithium chloride or calcium chloride solution, the mass concentration is 3wt%-8wt%, and the soaking time is 12-24h.

[0019] The specific steps of the washing are soaking in deionized water for 10h-72h, and changing water 1-3 times during the soaking;

[0020] The specific method of the drying is freezing at-30-40℃ for 6-12h, and vacuum drying in a freeze dryer for 24-48h.

[0021] Preferably, in S4, the amount of the added composite hygroscopic material accounts for 50%-100% of the total mass of polyvinyl alcohol and calcium citrate in the solution, and the concentration of calcium citrate is 10wt%-20wt%.

[0022] Preferably, in S5, the soaking time is 10-20min, and the drying method is heating drying at 50-60℃ for 2-6h.

[0023] According to the preparation method, a low-temperature regenerative dehumidification rotor based on hydrophilic-hydrophobic reversible conversion is prepared.

[0024] Therefore, the preparation method of the low-temperature regenerative dehumidification rotor based on hydrophilic-hydrophobic reversible conversion has the following beneficial effects:

[0025] (1) The method is simple and green, and the regeneration of the rotor is realized at a lower temperature by using the mechanism of hydrophilic-hydrophobic reversible conversion. The regeneration principle is based on the temperature-sensitive characteristics of the hygroscopic material. When the temperature is lower than 35℃, the hygroscopic material exhibits hydrophilicity and can effectively adsorb the moisture in the air to achieve the purpose of air dehumidification. When the temperature is greater than 35℃, the material exhibits hydrophobicity, and the moisture is desorbed to realize the regeneration of the hygroscopic material. The energy consumption in the dehumidification process of the rotor can be effectively reduced to achieve the purpose of energy saving and emission reduction.

[0026] (2) The lower regeneration temperature in the application also means that the hygroscopic material can be regenerated in a safer way compared with molecular sieve and silica gel adsorbents, thereby reducing the risk in the use process. At the same time, the lower regeneration temperature enables the use of low-grade heat energy such as solar energy and tail gas waste heat for regeneration, thereby realizing efficient utilization of energy.

[0027] (3) The polyvinyl alcohol used as the binder in the present application can also react with the hydrophilic-hydrophobic material, further enhancing the mechanical properties of the material, so that the material can be more firmly attached to the substrate, avoiding the occurrence of dropping slag, and the polyvinyl alcohol does not affect the hydrophilic-hydrophobic conversion characteristics of the material.

[0028] (4) Compared with the 120-180℃ regeneration temperature of molecular sieve, the regeneration temperature of the material can be reduced to 40-50℃, which makes us choose other woven materials as the substrate in addition to glass fiber and ceramic fiber and other high-temperature resistant materials, and also reduces the risk of fire during use.

[0029] The technical solutions of the present application will be further described in detail below by means of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The scanning electron microscope images of the present application example 1, comparative example 1 (silica gel), comparative example 2 (molecular sieve);

[0031] Figure 2 The contact angle of the present application example 1 at different temperatures;

[0032] Figure 3 The moisture adsorption amount of the present application example 1, comparative example 1 (silica gel), comparative example 2 (molecular sieve) changes with time under the condition of 27℃, 60% relative humidity environment;

[0033] Figure 4 The desorption curve of the present application example 1, comparative example 1 (silica gel), comparative example 2 (molecular sieve) under the condition of 50℃;

[0034] Figure 5 The dehumidification amount of the dehumidification wheel prepared by the present application example 1, comparative example 1, comparative example 2 under the same working condition;

[0035] Figure 6 The physical picture of the present application example 1. DETAILED DESCRIPTION

[0036] The technical solutions of the present application will be further described in detail below by means of the accompanying drawings and examples.

[0037] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the present application will be described clearly and completely below by combining the drawings in the present application. Obviously, the described examples are part of the examples of the present application, not all examples.

[0038] Example 1

[0039] (1) N-isopropylacrylamide (20 g) and N,N'-methylenebisacrylamide (2 g) as crosslinking agent were dissolved in 500 ml water and stirred at room temperature for 12 h. Then, ammonium peroxodisulfate as initiator (10 ml, 0.5 M) and N,N'-tetramethylethylenediamine (30 ml, 5 M) as oxidation initiator were added and reacted at 5 °C for 12 h.

[0040] (2) The resulting material was immersed in 8 wt% calcium chloride solution for 12 h, and then washed with deionized water for 24 h. Next, the material was frozen at -35 °C for 12 h, and dried in a vacuum freeze-drier for 48 h to obtain a composite hydrogel material of about 40 g.

[0041] (3) Polyvinyl alcohol type 105 (25 g, alcoholysis degree 98%-99%) and calcium citrate (20 g) were added to 500 ml water, and the mixture was dissolved by heating and stirring, and then cooled to a polyvinyl alcohol-calcium citrate mixed solution, which was ready for use.

[0042] (4) The composite hydrogel material prepared in step (2) (20 g) was added to the polyvinyl alcohol-calcium citrate mixed solution prepared in step (3) and stirred for 12 h to obtain a gel material-polyvinyl alcohol mixture, hereinafter referred to as the mixture.

[0043] (5) The prepared blank rotating disc (50 g in weight) was immersed in the mixture, ultrasonically shaken for 10 min, taken out, drained, and dried to ensure that the rotating disc holes were not blocked. After repeating the above steps three times, a rotating disc product (about 90 g in weight) was obtained.

[0044] Comparative Example 1

[0045] The blank rotating disc was immersed in a 20 wt% aqueous sodium silicate solution and dried, and then reacted in a sulfuric acid solution at pH = 0.5 for 3 h and dried to obtain a silica gel rotating disc, the main component of which was Na2O-nSiO2.

[0046] Comparative Example 2

[0047] Commercial molecular sieve rotating disc, the main component of which was 13X molecular sieve.

[0048] Material Characterization

[0049] From Figure 1 It can be seen that the appearance of the actual product is basically the same, because the specifications of the blank rotating discs used are consistent. From Figure 1 It can be observed that the surface of Example 1 has obvious composite hygroscopic hydrogel adhesion, and the material prepared on the surface is well adhered to the surface of the blank rotating disc.

[0050] For Example 1, the change of the surface hydrophilicity and hydrophobicity of the product with temperature was determined, and the contact angle of the material at 25℃ and 50℃ was measured by a contact angle measuring instrument, and the results are shown in Table 1. Figure 2 It can be seen that the contact angle is 30.3° at 25℃, which is hydrophilic, and the contact angle is 109.6° after drying at 50℃ for a period of time, which is hydrophobic, indicating that the material has undergone a change in hydrophilicity and hydrophobicity with temperature.

[0051] Performance test

[0052] All performance tests were carried out in a constant temperature and humidity chamber, hereinafter referred to as the chamber, to maintain a relatively stable environment temperature and humidity.

[0053] Moisture absorption performance test: after completely drying Example 1, Comparative Example 1 and Comparative Example 2, they were placed in a constant temperature and humidity chamber, and the temperature and humidity were set to 27℃ / 60% relative humidity. The initial mass M0 of each was recorded, and the mass M was recorded every 5 minutes x , and the relative moisture absorption amount was calculated, and the calculation method was:

[0054]

[0055] By calculation, the moisture absorption curve shown in Figure 3 was obtained, and from Figure 3 we can see that the moisture absorption rate of Example 1 is greater than that of Comparative Example 1 and Comparative Example 2 under the same experimental conditions, indicating that the moisture absorption capacity of Example 1 is stronger than that of Comparative Example 1 and Comparative Example 2.

[0056] Regeneration performance test: the initial mass M0 of Example 1, Comparative Example 1 and Comparative Example 2 was recorded, and after complete adsorption, the weight M m was recorded, and then the samples were placed in a 50℃ chamber, and the mass M x of each sample was recorded every 5 minutes, and the percentage of residual moisture was calculated, and the calculation formula was:

[0057]

[0058] The calculation result is Figure 4 . From Figure 4 we can see that under the conditions of the chamber, the mass of moisture of Example 1 decreases the most in the same time, and far ahead of Comparative Example 1 and Comparative Example 2, indicating that Example 1 can be well regenerated at 50℃.

[0059] Figure 5 The dehumidification capacity of the dehumidification runner obtained by Example 1, Comparative Example 1 and Comparative Example 2 under the working conditions of inlet air speed 2m / s, inlet temperature 27℃, relative humidity 60%(moisture content 13.14g / kg), and regeneration temperature 50℃.

[0060] The following table is the basic parameters of the rotating wheel of Example 1, Comparative Example 1 and Comparative Example 2 of the present application

[0061] Item Example 1 Comparative Example 1 Comparative Example 2 Size 150 x 20 mm 150 x 20 mm 150 x 20 mm Inlet air velocity 2 m / s 2 m / s 2 m / s Rotation speed 0.5 r / min 0.5 r / min 0.5 r / min Average dehumidification amount 2.62 g / kg 1.56 g / kg 1.02 g / kg

[0062] Figure 6 Figure 1 is a physical picture of Example 1, which shows that the surface is loaded with a large amount of moisture-absorbing material and there is no hole blockage.

[0063] Therefore, the preparation method of the low-temperature regenerative dehumidification rotating wheel based on the reversible conversion of hydrophilic and hydrophobic has the characteristics of low-temperature regeneration, which can effectively reduce the energy consumption in the dehumidification process of the rotating wheel, and achieve the purpose of energy saving and emission reduction. Moreover, the dehumidification rotating wheel can also well adsorb water vapor in the air at a lower temperature, achieving the purpose of air dehumidification.

[0064] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application but not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing a low-temperature regenerative dehumidification rotor based on reversible hydrophilicity-hydrophobicity transformation, characterized in that, Includes the following steps: S1. Pre-treat the glass fiber paper with a polyvinyl alcohol aqueous solution, then press a portion of the glass fiber paper into a corrugated paper using a corrugating machine, then stack the corrugated paper with another portion of glass fiber paper, roll them into a disc shape, and dry them to obtain a blank roller. S2. Dissolve N-isopropylacrylamide and crosslinking agent in water and stir until homogeneous. Then add initiator and accelerator to react and obtain poly(N-isopropylacrylamide) moisture-absorbing material. The accelerator is N,N'-tetramethylethylenediamine, and the amount added is 80%-90% of the total mass of N-isopropylacrylamide and crosslinking agent. S3. The poly-N-isopropylacrylamide material obtained in S2 is immersed in an inorganic salt solution, and then washed and dried to obtain a composite moisture-absorbing material based on reversible hydrophilic-hydrophobic transformation; the specific drying method is to freeze at -30-40℃ for 6-12 hours and then vacuum dry in a freeze dryer for 24-48 hours; the inorganic salt solution is a lithium chloride or calcium chloride solution with a mass concentration of 3wt%-8wt% and an immersion time of 12-24 hours. S4. Take the composite moisture-absorbing material obtained in S3, and mix it with polyvinyl alcohol and calcium citrate in water at a certain ratio. Stir thoroughly and then sonicate to disperse it evenly to obtain a mixed suspension of moisture-absorbing material-polyvinyl alcohol-calcium citrate. The amount of composite moisture-absorbing material added accounts for 50%-100% of the total mass of polyvinyl alcohol and calcium citrate in the solution, and the concentration of calcium citrate is 10wt%-20wt%. S5. After immersing the blank rotor obtained in S1 in the mixed suspension obtained in S4 for a period of time, remove it, blow away the residual moisture in the rotor cavity, and dry it. Repeat this process 2-3 times to obtain a low-temperature regeneration dehumidifying rotor based on hydrophilic-hydrophobic reversible transformation. The immersion time is 10-20 minutes, and the drying method is to heat and dry at 50-60℃ for 2-6 hours.

2. The method for preparing a low-temperature regenerative dehumidification impeller based on reversible hydrophilicity-hydrophobicity as described in claim 1, characterized in that: In both S1 and S4, the degree of alcoholysis of the added polyvinyl alcohol aqueous solution is above 95%, and the concentration is 5-10 wt%.

3. The method for preparing a low-temperature regenerative dehumidification impeller based on reversible hydrophilicity-hydrophobicity as described in claim 2, characterized in that: In step S2, 90%-95% of N-isopropylacrylamide and 5%-10% of a crosslinking agent, wherein the crosslinking agent is N,N'-methylenebisacrylamide, are added.

4. The method for preparing a low-temperature regenerative dehumidification impeller based on reversible hydrophilicity-hydrophobicity as described in claim 3, characterized in that: In S2, the initiator is ammonium persulfate, and the amount added is 5%-10% of the total mass of N-isopropylacrylamide and crosslinking agent.

5. The method for preparing a low-temperature regenerative dehumidification impeller based on reversible hydrophilicity-hydrophobicity as described in claim 4, characterized in that: In the S2 reaction, the reaction time is 5-12 hours and the reaction temperature is 0-6°C.

6. The method for preparing a low-temperature regenerative dehumidification impeller based on reversible hydrophilicity-hydrophobicity as described in claim 5, characterized in that: In step S3, the specific washing steps are to soak in deionized water for 10-72 hours, changing the water 1-3 times during this period.

7. A low-temperature regenerative dehumidification impeller based on reversible hydrophilicity / hydrophobicity conversion, characterized in that: It is prepared according to any one of claims 1-6.

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