Humidity control liquid, method for manufacturing a humidity control liquid, humidity control method, and humidity control apparatus

Abstract

To provide a humidity control liquid with reduced corrosiveness to metals, a method for manufacturing the humidity control liquid, a humidity control method, and a humidity control apparatus. [Solution] A method for producing a humidity control liquid, comprising the steps of: preparing an additive by mixing an aqueous solution of the ionic liquid containing lithium chloride, water, a water-soluble rust inhibitor, and an ionic liquid with a water-soluble rust inhibitor; and mixing an aqueous solution of lithium chloride containing lithium chloride and water with the additive; and a humidity control device equipped with a humidity control section that brings the humidity control liquid into contact with air.

Description

Technical Field

[0001] The present disclosure relates to a humidity control liquid, a method for manufacturing the humidity control liquid, a humidity control method, and a humidity control device.

Background Art

[0002] As an air conditioner that efficiently realizes ventilation and humidity control, a liquid desiccant air conditioner using a humidity control liquid is known. In a liquid desiccant air conditioner, the temperature and humidity of the air in contact with the humidity control liquid are controlled by controlling the temperature and concentration of the humidity control liquid. As a humidity control liquid having high humidity control performance, for example, an aqueous lithium chloride solution containing lithium chloride and water is used.

[0003] However, since an aqueous lithium chloride solution has strong corrosiveness to metals, in a liquid desiccant air conditioner using an aqueous lithium chloride solution as a humidity control liquid, measures such as limiting the metal used in the metal parts in contact with the aqueous lithium chloride solution to titanium are taken. In addition, it is known to use a liquid other than an aqueous lithium chloride solution such as an ionic liquid as a humidity control liquid that suppresses corrosion of metals (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An aqueous lithium chloride solution has a sterilizing action, and lithium chloride as a humidity control agent does not vaporize and is a stable substance, so it is preferable as a humidity control liquid. On the other hand, metal is used as a main material constituting a humidity control device, a heat exchanger, etc. that may come into contact with the humidity control liquid. In particular, copper is preferably used for these devices because of its good workability, corrosion resistance, thermal conductivity, etc. Therefore, it was desirable to suppress the corrosiveness of metals in humidity control solutions using lithium chloride aqueous solutions.

[0006] One embodiment of this disclosure aims to provide a humidity control liquid with reduced corrosiveness to metals, a method for producing the humidity control liquid, a humidity control method, and a humidity control apparatus. [Means for solving the problem]

[0007] This disclosure includes the following aspects:

[0008] <1> A humidity control solution containing lithium chloride, water, a water-soluble rust inhibitor, and an ionic liquid. <2> The water-soluble rust inhibitor is benzotriazole. <1> The humidity control liquid described above. <3> Ionic liquids have water absorption and release properties. <1> or <2> The humidity control liquid described above. <4> Ionic liquids contain imidazolium. <1> ~ <3> A humidity control liquid listed in any one of the following. <5> A method for producing a humidity control solution, comprising the steps of: preparing an additive by mixing an aqueous solution of an ionic liquid containing an ionic liquid and water with a water-soluble rust inhibitor; and mixing an aqueous solution of lithium chloride containing lithium chloride and water with the additive. <6> The additives are mixed in a range of 1% to 45% by mass, based on the total mass of the humidity control liquid. <5> A method for producing the humidity control liquid described above. <7> A lithium chloride aqueous solution contains lithium chloride in an amount ranging from 20% to 40% by mass, based on the total mass of the lithium chloride aqueous solution. <5> or <6> A method for producing the humidity control liquid described above. <8> <1> ~ <4> A humidity control method that uses one of the humidity control liquids described in any one of the following. <9> <1> ~ <4> A humidity control device comprising a humidity control section that brings a humidity control liquid described in any one of the above into contact with air. <10> At least a portion of the part that comes into contact with the humidity control liquid contains copper. <9> The humidity control device described above. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, it is possible to provide a humidity control liquid with reduced corrosiveness, a method for producing the humidity control liquid, a humidity control method, and a humidity control apparatus. [Brief explanation of the drawing]

[0010] [Figure 1] This is an explanatory diagram illustrating the configuration of a liquid desiccant air conditioner. [Figure 2] This graph shows the relationship between elapsed time (hours) and the weight ratio of the tube in the examples and comparative examples. [Modes for carrying out the invention]

[0011] The following describes in detail specific embodiments of the humidity control liquid, the method for manufacturing the humidity control liquid, and the humidity control apparatus relating to this disclosure. However, the humidity control liquid, the method for manufacturing the humidity control liquid, and the humidity control apparatus relating to this disclosure are not limited to the embodiments described below, and can be implemented with appropriate modifications within the scope of the purpose of this disclosure.

[0012] In this disclosure, a numerical range indicated using "~" means a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages within this disclosure, an upper or lower limit stated in one numerical range may be replaced with an upper or lower limit in another numerical range described in stages. Furthermore, in numerical ranges described herein, an upper or lower limit stated in one numerical range may be replaced with a value shown in an example. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, "mass%" and "weight%" are synonymous. In this disclosure, unless otherwise specified, the amount of each component refers to the total amount of multiple substances if there are multiple substances corresponding to each component. In this disclosure, "room temperature" means 25°C.

[0013] <Humidity control liquid> The humidity control liquid according to one embodiment of the present disclosure contains lithium chloride, water, a water-soluble rust inhibitor, and an ionic liquid. In one embodiment of the present disclosure, the lithium chloride and a part of the water contained in the humidity control liquid are based on the aqueous lithium chloride solution used when producing the humidity control liquid, and the ionic liquid and a part of the water are based on the aqueous ionic liquid solution used when producing the humidity control liquid.

[0014] The humidity control liquid containing an aqueous lithium chloride solution has high humidity control performance, has a sterilizing effect, and is a stable substance because lithium chloride does not vaporize. Therefore, it is preferably used as a humidity control liquid for humidity control devices such as liquid desiccant air conditioners. Specifically regarding the humidity control performance, according to the humidity control liquid containing an aqueous lithium chloride solution, the water vapor pressure of the contacted air can be accurately controlled by the combination of the temperature and the concentration of lithium chloride, and it is possible to obtain air with a desired temperature and humidity. In particular, since there is no need to cool the air to the dew point temperature desired for dehumidification, the temperature of the heat source can be raised compared to the general cooling dehumidification method, and it is also excellent in energy saving.

[0015] However, since the aqueous lithium chloride solution has strong corrosiveness to metals, in a humidity control device using a humidity control liquid containing an aqueous lithium chloride solution, when the part contacting the humidity control liquid contains metal, it was necessary to take measures such as using a metal having corrosion resistance to an aqueous lithium chloride solution such as titanium.

[0016] The inventor considered reducing the corrosiveness to metals by adding a rust inhibitor to the humidity control liquid in order to enable the use of inexpensive general-purpose metals centered on copper for the metal parts of the humidity control device that the humidity control liquid containing an aqueous lithium chloride solution contacts. However, for example, when a water-soluble rust inhibitor that can reduce the corrosiveness to copper is added to an aqueous lithium chloride solution, at room temperature such as 25°C, which is the temperature at which the humidity control liquid is used, the water-soluble rust inhibitor hardly dissolves in the aqueous lithium chloride solution, and it was found that the water-soluble rust inhibitor may precipitate due to a temperature drop even when the water-soluble rust inhibitor is dissolved at a high temperature.

[0017] Therefore, in order to obtain a humidity control liquid that maintains high humidity control performance while reducing corrosiveness, further investigation was carried out on adding a water-soluble rust inhibitor to an aqueous lithium chloride solution. As a result, it was found that the water-soluble rust inhibitor is likely to be compatible with the aqueous lithium chloride solution in the presence of an ionic liquid. It was also found that a humidity control liquid obtained by mixing an ionic liquid in which a water-soluble rust inhibitor is dissolved and an aqueous lithium chloride solution has particularly reduced corrosiveness against copper and copper alloys and has high humidity control performance.

[0018] Although the mechanism by which the above effects are achieved is not clear, it is presumed that the water-soluble rust inhibitor dispersed in the aqueous lithium chloride solution due to the presence of the ionic liquid functions appropriately in the system and forms a film on a metal such as copper or a copper alloy, thereby imparting to the metal the effect of reducing the corrosiveness of the aqueous lithium chloride solution against the metal.

[0019] (aqueous lithium chloride solution) The humidity control liquid contains lithium chloride and water. Since lithium chloride has hygroscopicity, it is used as a humidity control agent. The humidity control agent may be used alone or in combination of two or more. The humidity control liquid containing a humidity control agent and water controls the humidity of the air by controlling the vapor-liquid equilibrium vapor pressure by controlling the concentration. For example, when the humidity of the air is high, concentration is performed to increase the concentration of the humidity control agent in the humidity control liquid by heating the humidity control liquid to evaporate water, and the concentrated humidity control agent absorbs moisture in the air to lower the humidity. On the other hand, when the humidity of the air is low, the concentration of the humidity control agent in the humidity control liquid is decreased by supplying water to the humidity control liquid, and the humidity is increased by imparting moisture to the air with the humidity control liquid having a decreased concentration.

[0020] As the humidity control agent, in addition to lithium chloride, metal halide salts such as lithium bromide and calcium chloride can be used. Since an aqueous lithium chloride solution has a sterilizing effect, lithium chloride does not vaporize, and it is a stable and safe substance, it is preferable to use lithium chloride as the humidity control agent. In addition, an ionic liquid or an aqueous ionic liquid solution can also be used as the humidity control agent. The ionic liquid will be described later.

[0021] The water used in the humidity control solution should preferably be of high purity, from the standpoint of properly controlling humidity and preventing indoor pollution, as well as from the standpoint of concentrating residues through evaporation. For example, it is preferable to use RO water (reverse osmosis water) purified using a reverse osmosis membrane.

[0022] The concentration of lithium chloride in the lithium chloride aqueous solution fluctuates for humidity control, but is preferably within the range of 20% to 40% by mass, based on the total mass of the lithium chloride aqueous solution. More preferably, it is within the range of 25% to 40% by mass, and even more preferably, within the range of 25% to 35% by mass. Within this range, the relative humidity of the air in contact with the humidity control solution can be adjusted more appropriately.

[0023] The content of the lithium chloride aqueous solution in the humidity control solution is preferably within the range of 55% to 99% by mass, based on the total mass of the humidity control solution. In the humidity control solution, the remainder other than the additives described below may be the lithium chloride aqueous solution. In the humidity control solution, the amount and concentration of the rust inhibitor can be determined based on the amount of lithium chloride, the concentration of the lithium chloride aqueous solution, the temperature, etc., and the concentration or amount of the ionic liquid aqueous solution can be determined based on the amount and concentration of the rust inhibitor, etc. When the content of the lithium chloride aqueous solution in the humidity control solution is usually within the above range, the humidity control performance of the humidity control solution can be exhibited more appropriately.

[0024] (Water-soluble rust inhibitor) The humidity control liquid contains a water-soluble rust inhibitor. As the water-soluble rust inhibitor, conventionally used known rust inhibitors (such as those described in "Corrosion Reactions and Their Control" by HH Yuric and RW Levy, published by Sangyo Tosho Co., Ltd.) can be used. Specifically, examples include organic amines with 7 to 18 carbon atoms, aliphatic amides with 6 to 18 carbon atoms, aromatic amides, cyclohexylamine nitride, benzotriazole, mercaptobenzothiazole, N,N'-disalicylidene-1,2-diaminopropane, and alizarin.

[0025] Of these, benzotriazole and mercaptobenzothiazole are preferred because they are highly effective in reducing the corrosiveness of copper and its alloys used in humidity control devices, and benzotriazole is more preferred because it has a particularly high rust-preventive effect on copper. Furthermore, a single type of water-soluble rust inhibitor may be used, or a mixture of two or more types may be used.

[0026] (Ionic liquid aqueous solution) The humidity control liquid contains an ionic liquid. An ionic liquid is a salt that is liquid at room temperature and contains both cations and anions. Many types of ionic liquids are known, and conventionally used known ionic liquids can be used. It is preferable that the ionic liquid is miscible with water at the temperature of the operating environment. It is preferable to use the ionic liquid as an aqueous solution of the ionic liquid mixed with water. Note that one type of ionic liquid may be used, or two or more types may be mixed and used.

[0027] It is preferable that the ionic liquid itself or the aqueous solution of the ionic liquid has water absorption and release properties. The water absorption and release properties of the ionic liquid or aqueous solution of the ionic liquid (hereinafter referred to as "ionic liquid, etc.") are preferably such that they exhibit excellent water absorption and release performance under conditions where the ionic liquid, etc. is used as a humidity control liquid. These conditions include the temperature of the ionic liquid, etc. and the environment in which it is used. Therefore, it is preferable that the ionic liquid, etc., has humidity control properties. In other words, it is preferable that the ionic liquid, etc., is used as a humidity control agent. This is because the humidity control agent as a whole can be used as a humidity control liquid with more desirable humidity control properties. In this specification, "water absorption and release" includes "hygroscopicity," meaning the ability to absorb and release moisture contained in the air, such as water vapor and water droplets. Furthermore, it is preferable that the ionic liquid has antibacterial or germicidal properties. It is preferable that the ionic liquid has germicidal properties and, in the humidity control solution mixed with an aqueous lithium chloride solution, does not impair the germicidal properties.

[0028] The viscosity of the ionic liquid, etc., is preferably such that it has appropriate fluidity for use as a humidity control solution when mixed with an aqueous lithium chloride solution. There is no particular lower limit, but as an upper limit, for example, at a concentration used as an aqueous ionic liquid solution, it is preferably 50 mPa·s or less at room temperature, and more preferably 30 mPa·s or less.

[0029] Examples of ionic liquids include those in which the cation is an imidazolium, ammonium, or pyridinium compound. Specifically, those described in Japanese Patent Publication No. 2019-063761 and Japanese Patent Publication No. 2020-030004 can be used.

[0030] Among these, ionic liquids containing imidazolium cations are preferred due to their suitability for humidity control and antibacterial or disinfectant properties. Furthermore, those that can suitably dissolve water-soluble rust inhibitors and are miscible with aqueous lithium chloride solutions are preferred, and 1,3-dimethylimidazolium acetate, 1,3-dimethylimidazolium acetate, 1,3-dimethylimidazolium methylsulfonate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1,3-dimethylimidazolium propionate, etc., can be suitably used. Furthermore, one type of ionic liquid may be used, or two or more types may be mixed and used.

[0031] The concentration of the ionic liquid in an aqueous solution of an ionic liquid is not particularly limited, but it is preferably 50% to 95% by mass, and more preferably 65% ​​to 80% by mass, based on the total mass of the aqueous solution of the ionic liquid.

[0032] Commercially available ionic liquid aqueous solutions may be used. Examples of commercially available products include imidazolium salt aqueous solutions (product name: CreCOPlus®, manufactured by Evonik). CreCOPlus is an imidazolium salt aqueous solution in which 80% by mass is imidazolium salt, based on the total mass.

[0033] (Additives) The additive contains a water-soluble rust inhibitor, an ionic liquid, and water. In the additive, the ionic liquid and water refer to an aqueous solution of the ionic liquid. That is, the additive contains an aqueous solution of the ionic liquid and a water-soluble rust inhibitor. The additive is added to an aqueous lithium chloride solution prepared from lithium chloride and water. By adding the additive to the aqueous lithium chloride solution, it becomes possible to mix the aqueous lithium chloride solution with a water-soluble rust inhibitor while suppressing the precipitation of the water-soluble rust inhibitor, thereby imparting a corrosiveness-reducing effect to the aqueous lithium chloride solution. Furthermore, one type of additive may be used, or two or more types may be mixed and used.

[0034] The amount of water-soluble rust inhibitor used in the additive is preferably in the range of 3% to 20% by mass, and more preferably in the range of 5% to 15% by mass, based on the total mass of the additive, from the viewpoint of solubility in aqueous ionic liquid solutions. The amount of water-soluble rust inhibitor used in the entire humidity control solution is preferably 0.02 M (mol / L) to 0.8 M, and more preferably 0.04 M to 0.6 M.

[0035] The proportion of additives in the humidity control solution can be adjusted to any desired ratio to obtain a homogeneous solution. Based on the total mass of the humidity control solution, the amount of additives is preferably, for example, 1% to 45% by mass, and more preferably within the range of 5% to 40% by mass.

[0036] The proportion of additives in the humidity control solution may be determined according to the desired humidity control solution. If the purpose is to utilize the water absorption / discharge or humidity control properties of lithium chloride, the proportion of additives can be such that the lithium chloride aqueous solution is the main component, and the additives are added in a proportion that allows the corrosiveness reduction performance to be exhibited. In this case, the proportion of additives in the humidity control solution is preferably 1% to 15% by mass, and more preferably 3% to 8% by mass, based on the total mass of the humidity control solution. In addition, the mixing ratio of additives can be determined by adjusting the physical properties of the humidity control liquid, the temperature at which the humidity control liquid is used, and the type of humidity control device that uses the humidity control liquid.

[0037] (Other ingredients) The humidity control liquid may contain lithium chloride, water, a water-soluble rust inhibitor, and other components other than those of the ionic liquid. These other components may include known additives conventionally used in humidity control liquids, and one or more components may be used. While there are no specific limitations on other components, known additives such as flame retardants, colorants, defoamers, viscosity modifiers, and pH adjusters can be mentioned. Other components in the humidity control solution may be used as long as they do not impair the effectiveness of the solution.

[0038] <Method for manufacturing humidity control liquid> One embodiment of the present disclosure is a method for producing a humidity control liquid, which includes a step of preparing an additive by mixing an aqueous solution of an ionic liquid containing an ionic liquid and water with a water-soluble rust inhibitor (hereinafter referred to as the additive preparation step), and a step of mixing an aqueous solution of lithium chloride containing lithium chloride and water with the additive (hereinafter referred to as the mixing step).

[0039] The above manufacturing method allows for the suppression of precipitation and optimal dissolution of a water-soluble rust inhibitor that was previously almost insoluble in lithium chloride aqueous solution and, even if it dissolved in the lithium chloride aqueous solution upon heating, precipitated at the operating temperature of the humidity control solution. This makes it possible to reduce the corrosiveness of the humidity control solution using lithium chloride aqueous solution to metals.

[0040] In particular, it becomes possible to dissolve benzotriazole, a water-soluble rust inhibitor with high corrosion-reducing performance against copper and copper alloys, in an amount that exhibits suitable corrosion-reducing performance in an aqueous lithium chloride solution, thereby imparting corrosion-reducing properties against copper-containing metals to a humidity control solution using an aqueous lithium chloride solution. Furthermore, after dissolving benzotriazole in the humidity control solution, precipitation of benzotriazole can be suppressed within the temperature range in which the humidity control solution is used.

[0041] Furthermore, the method for producing the humidity control solution is not limited to the method described above. Any method that can ultimately produce the humidity control solution can be used. For example, the method may include the steps of preparing a stock solution by mixing an aqueous solution of the ionic liquid containing an ionic liquid and water with an aqueous solution of lithium chloride containing lithium chloride and water, and mixing a water-soluble rust inhibitor with the stock solution.

[0042] According to one embodiment of the present disclosure, a method for producing a humidity control liquid can be provided that reduces the corrosiveness of metals such as copper and copper alloys. For example, copper is the main material for most heat exchangers, and even when a material other than copper is the main material, copper is often included in brazing materials, etc., because of its good workability, corrosion resistance, and thermal conductivity. Therefore, a humidity control solution consisting of a lithium chloride aqueous solution, which is suitable as a humidity control liquid, can be used in commonly used heat exchangers, thereby greatly expanding the range of applications for humidity control solutions containing lithium chloride aqueous solution. For this reason, since many parts used in air conditioners are made of copper or copper alloys, the value of a liquid humidity control agent that does not corrode copper is extremely high.

[0043] (Additive adjustment process) The method for producing a humidity control liquid includes an additive preparation step in which an additive is prepared by mixing an aqueous solution of an ionic liquid containing an ionic liquid and water with a water-soluble rust inhibitor.

[0044] In the additive preparation process, an ionic liquid aqueous solution and a water-soluble rust inhibitor are prepared separately and then mixed together. In the additive preparation process, there are no particular restrictions on the method of mixing the ionic liquid aqueous solution and the water-soluble rust inhibitor; they can be mixed using conventionally known methods.

[0045] In addition, during the additive preparation process, various operations such as heating and stirring may be performed when mixing the ionic liquid aqueous solution with the water-soluble rust inhibitor.

[0046] (Mixing process) The method for producing a humidity control solution includes a mixing step of mixing an additive with an aqueous solution of lithium chloride containing lithium chloride and water. The mixture prepared by the mixing step can be used as a humidity control solution.

[0047] In the mixing process, an aqueous solution of the ionic liquid containing the ionic liquid, water, and a water-soluble rust inhibitor is prepared, and an aqueous solution of lithium chloride containing lithium chloride and water is prepared, and these are mixed together. In the mixing process, there are no particular restrictions on the method of mixing the ionic liquid aqueous solution and the lithium chloride aqueous solution; they can be mixed using conventionally known methods.

[0048] In addition, during the mixing process, various operations such as heating and stirring, which are conventionally performed on lithium chloride aqueous solutions, ionic liquid aqueous solutions, etc., may be carried out. Furthermore, in the method for manufacturing the humidity control liquid, the preferred amounts of each component to be used are the same as those described above for the humidity control liquid.

[0049] <Humidity control methods> One embodiment of the humidity control method described herein involves controlling humidity using the above-mentioned humidity control liquid. By using the above-mentioned humidity control liquid, it is possible to control the humidity of the air with excellent energy efficiency and good humidity control.

[0050] The above humidity control method includes a step of bringing a humidity control liquid into contact with air. Regarding the principle of humidity control, according to Raoult's law, as the concentration of the humidity control agent in the humidity control liquid increases, the relative humidity of the air decreases when the air and humidity control liquid are in equilibrium. Therefore, the humidity of the air (vapor pressure of vapor-liquid equilibrium) can be adjusted by adjusting the concentration of the humidity control agent in the humidity control liquid.

[0051] By using a humidity control method according to one embodiment of this disclosure, the concentration of the humidity control agent contained in the humidity control liquid can be adjusted by conventionally known methods to suitably control humidity. The humidity control method may also be performed while ventilation is also performed.

[0052] <Humidity control device> One embodiment of the present disclosure is a humidity control device comprising a humidity control section that brings a humidity control liquid, which is one embodiment of the present disclosure described above, into contact with air. The humidity control section is a means for performing a humidity control function that adjusts the humidity of the air taken in.

[0053] Specifically, the humidity control unit can employ means to bring the humidity control liquid into contact with air, and various conventionally known methods can be used. For example, means can be used to supply the humidity control liquid from the top to the bottom of the processing machine and to pass the taken-in air through the inside of the processing machine.

[0054] Furthermore, the humidity control unit may also incorporate a temperature control function to adjust the temperature of the intake air. This temperature control function can be achieved, for example, by adjusting the temperature of the humidity control liquid in the humidity control unit.

[0055] In a humidity control device, at least a portion of the parts that come into contact with the humidity control liquid may contain copper. In some humidity control devices, the humidity control liquid is heated by a heat exchanger. Due to its high thermal conductivity, materials containing copper are often used for heat exchangers. Therefore, using a humidity control liquid that reduces corrosion to metals in a humidity control device allows for the use of various types of heat exchangers and is also preferable in terms of thermal efficiency.

[0056] A specific example of a humidity control device equipped with a humidity control unit is a liquid desiccant air conditioner. An example of a liquid desiccant air conditioner is shown in Figure 1. As shown in Figure 1, the liquid desiccant air conditioner 10 includes a processing unit 20 and a regeneration unit 30. The processing unit 20 functions as a humidity control unit.

[0057] The processing machine 20 takes in air from the air intake port 21 and discharges the processed air from the exhaust port 22. The processing unit 20 is equipped with a humidity control liquid 23 and a gas-liquid contactor 24. The processing unit 20 is also equipped with a humidity control liquid outlet 25 and a humidity control liquid supply outlet 26. The adjusted humidity control liquid 23 is supplied to the upper part of the gas-liquid contactor 24, and the humidity control liquid 23 passes through the inside of the gas-liquid contactor 24 and is stored in the lower part of the processing unit 20. The stored humidity control liquid 23 is discharged from the humidity control liquid outlet 24 and supplied to the regenerator 30 via the heat exchanger 41.

[0058] The regenerator 30 takes in air through the air intake port 31 and discharges the processed air through the exhaust port 32. The regenerator 30 is equipped with a humidity control liquid 33 and a gas-liquid contactor 34. The regenerator 30 also has a humidity control liquid outlet 35 and a humidity control liquid supply outlet 36. The adjusted humidity control liquid 33 is supplied to the upper part of the gas-liquid contactor 34, and the humidity control liquid 33 passes through the inside of the gas-liquid contactor 34 and is stored in the lower part of the regenerator 30. The stored humidity control liquid 33 is discharged from the humidity control liquid outlet 35 and supplied to the processor 20 via the heat exchanger 41. Heat transfer is performed to the multiple heat exchangers 41 by a heat pump 42.

[0059] In the processing unit 20, during dehumidification, the cooled humidity control liquid 23 is brought into contact with air to cool and dehumidify the air. In the regeneration unit 30, the humidity control liquid is heated to concentrate it. During humidification, the heated humidity control liquid 23 is brought into contact with air to heat and humidify the air. In the regeneration unit 30, water is supplied to the humidity control liquid 33 to dilute it. [Examples]

[0060] Next, the humidity control liquids, etc. related to this disclosure will be described in more detail by reference to examples. However, the humidity control liquids, etc. related to this disclosure are not limited in any way by these examples.

[0061] In the examples and comparative examples, a humidity control solution was prepared according to the following procedure. Then, the corrosion reduction performance on metals was evaluated using the obtained humidity control solution. The results are shown in Table 1.

[0062] [Examples] <Adjustment of humidity control solution> (Preparation of additive A) An additive containing an ionic liquid aqueous solution and a water-soluble rust inhibitor was prepared. As the ionic liquid aqueous solution, an 80% by mass imidazolium salt aqueous solution (product name: CreCOPlus, manufactured by Evonik) was used, and benzotriazole was used as the water-soluble rust inhibitor. To the entire 400 ml of conditioned solution A, which contained 20 ml of additive A and 380 ml of lithium chloride aqueous solution, benzotriazole was mixed with 20 ml of CreCOPlus to obtain a concentration of 0.04 M (mol / L), and this was designated as additive A.

[0063] (Preparation of lithium chloride aqueous solution) A lithium chloride aqueous solution was prepared by adding tap water to lithium chloride to achieve a concentration of 30% by mass.

[0064] (Preparation of humidity control solution A) A humidity control solution A was prepared by mixing 20 mL of additive (approximately 5% by mass of the total mass of humidity control solution A) with 380 mL of lithium chloride aqueous solution (approximately 95% by mass of the total mass of humidity control solution A).

[0065] [Comparative Example] <Preparation of humidity control solution B> Humidity control solution B was prepared in the same manner as humidity control solution A in the example, except that a water-soluble rust inhibitor was not added. That is, only an aqueous solution of ionic liquid was used as additive B.

[0066] <Rating> Corrosion tests were conducted on humidity control liquids A and B as described below, and the amount of corrosion in the humidity control liquids at different time intervals was evaluated.

[0067] =Corrosion Test= The corrosion test was performed by placing 400 mL of humidification solution A into a lidded bottle, maintaining the temperature at 45°C, and stirring humidification solution A with a magnetic stirrer. The copper tube was suspended by nylon thread and adjusted to be positioned in the middle of the liquid level. The tube used was phosphorus-deoxidized copper (JIS C1220T), with an outer diameter of 15.88 mm, an inner diameter of 14.63 mm, and a length of 22 mm.

[0068] The time elapsed after immersion was measured, and at a certain time, the tube was removed and its weight was measured. After measuring the weight, the tube was immersed again in the humidity control solution. The weight of the tubes was measured a total of 11 times, from before immersion until approximately 3000 hours had passed.

[0069] The elapsed time from the start of immersion was recorded, and the weight was measured and recorded at regular intervals. Before measuring the weight, any attached compounds were removed, the samples were washed with pure water, and then thoroughly dried. Initially, a small amount of verdigris-like deposit was observed where the nylon thread had been in contact, and this was removed. No further deposits were observed thereafter. This explains the relatively large weight reduction observed during the initial weight measurement. Although humidity control solution A is a nearly colorless and transparent liquid, no visible changes were observed during the test, and no reaction was observed in a simple test using copper ion test paper capable of detecting copper ion concentrations of 2 mg / L or higher. The copper tubes appeared slightly darker, but the characteristic copper luster that occurs when benzotriazole is added was retained.

[0070] The elapsed time (in hours) and the weight of the tube were measured. The weight ratio and the weight loss rate were calculated, with the weight at the first measurement set as 1, and are listed in Table 1. As shown in Figure 2, a graph was created showing the relationship between elapsed time (hours) and weight ratio, which revealed that the weight of the tube hardly changed from approximately 200 hours to approximately 3000 hours.

[0071] As described above, corrosion tests were conducted on humidity control solution A, and a corrosion test was also conducted on humidity control solution B, which is the same mixture as humidity control solution A except that benzotriazole is not added, in the same manner as for humidity control solution A. In the case of humidity control solution B, after 24 hours, the liquid, which was initially almost colorless and transparent, had become cloudy with a bluish-green color, indicating that corrosion was progressing rapidly. Upon examining the copper tube's exterior, no deposits were observed, but it had completely lost its luster, suggesting that overall corrosion had progressed. The elapsed time (in hours) and the weight of the tube were measured, and the weight ratio (with the weight at the first measurement set as 1) and the weight loss rate were calculated and recorded in Table 1. If the test was not performed, it is indicated as blank in Table 1.

[0072] [Table 1]

[0073] As shown in Table 1 and Figure 2, in the example using humidity control liquid A, which is one embodiment of the present disclosure, it was confirmed that the weight of the tube hardly changed and no corrosion products were generated or grown during the elapsed time of approximately 3000 hours. In contrast, in the comparative example using humidity control liquid B, after 24 hours, the liquid, which was initially almost colorless and transparent, had become cloudy with a bluish-green color, indicating that corrosion was progressing rapidly. [Explanation of Symbols]

[0074] 10 Liquid Desiccant Air Conditioners 20 processing machines 21 Air intake 22 Exhaust vents 23. Humidity control liquid 24 Gas-liquid contactor 25 Humidity control liquid outlet 26. Humidity control liquid supply port 30 Recycler 31 Air intake 32 Exhaust vents 33. Humidity control liquid 34. Gas-liquid contactor 35 Humidity control liquid outlet 36. Humidity control liquid supply port 41 Heat exchanger 42 Heat pump

Claims

1. A humidity control solution containing lithium chloride, water, a water-soluble rust inhibitor, and an ionic liquid.

2. The humidity control liquid according to claim 1, wherein the water-soluble rust inhibitor is benzotriazole.

3. The ionic liquid is the humidity control liquid according to claim 1, which has water absorption and release properties.

4. The ionic liquid is the humidity control liquid according to claim 1, comprising imidazolium.

5. A step of preparing an additive by mixing an aqueous solution of an ionic liquid containing an ionic liquid and water with a water-soluble rust inhibitor, A step of mixing an aqueous lithium chloride solution containing lithium chloride and water with the additive, A method for producing a humidity control liquid containing the liquid.

6. The method for producing a humidity control liquid according to claim 5, wherein the additive is mixed in an amount ranging from 1% by mass to 45% by mass, based on the total mass of the humidity control liquid.

7. The method for producing a humidity control liquid according to claim 5, wherein the lithium chloride aqueous solution contains lithium chloride in an amount of 20% to 40% by mass, based on the total mass of the lithium chloride aqueous solution.

8. A humidity control method that uses a humidity control liquid according to any one of claims 1 to 4.

9. A humidity control device comprising a humidity control section that brings a humidity control liquid according to any one of claims 1 to 4 into contact with air.

10. The humidity control device according to claim 9, wherein at least a portion of the part that comes into contact with the humidity control liquid contains copper.

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