Humidity control liquid, method for producing humidity control liquid, humidity control method, and humidity control device

Abstract

Provided are: a humidity control liquid comprising lithium chloride, water, a water soluble rust prevention agent, and an ionic liquid; a method for producing the humidity control liquid comprising a step for preparing an additive by mixing an ionic liquid aqueous solution that contains an ionic liquid and water with a water soluble rust prevention agent, and a step for mixing a lithium chloride aqueous solution that contains lithium chloride and water with the additive; and a humidity control device comprising a humidity control unit that brings the humidity control liquid into contact with air.

Description

Humidifying liquid, method for producing humidifying liquid, humidifying method, and humidifying device

[0001] The present disclosure relates to a humidifying liquid, a method for producing the humidifying liquid, a humidifying method, and a humidifying device.

[0002] As an air conditioner that efficiently realizes ventilation and humidification, a liquid desiccant air conditioner using a humidifying liquid is known. In a liquid desiccant air conditioner, the temperature and humidity of the air in contact with the humidifying liquid are controlled by controlling the temperature and concentration of the humidifying liquid. As a humidifying liquid having high humidifying 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 humidifying liquid, measures such as limiting the metal used in the metal part in contact with the aqueous lithium chloride solution to titanium are taken. Also, it is known to use a liquid other than an aqueous lithium chloride solution, such as an ionic liquid, as a humidifying liquid that suppresses corrosion of metals (Patent Document 1).

[0004] Patent Document 1: Japanese Patent No. 6046294

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

[0006] An object of one embodiment of the present disclosure is to provide a humidifying liquid with reduced corrosiveness to metals, a method for producing the humidifying liquid, a humidifying method, and a humidifying device.

[0007] The present disclosure includes the following aspects.

[0008] <1> A humidity control solution comprising lithium chloride, water, a water-soluble rust inhibitor, and an ionic liquid. <2> The humidity control solution according to <1>, wherein the water-soluble rust inhibitor is benzotriazole. <3> The humidity control solution according to <1> or <2>, wherein the ionic liquid has water absorption and release properties. <4> The humidity control solution according to any one of <1> to <3>, wherein the ionic liquid contains imidazolium. <5> A method for producing a humidity control solution, comprising the steps of preparing an additive by mixing an aqueous solution of the ionic liquid containing the 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 method for producing a humidity control solution according to <5>, wherein the additive is mixed in a range of 1% to 45% by mass based on the total mass of the humidity control solution. <7> The method for producing a humidity control solution according to <5> or <6>, wherein the aqueous solution of lithium chloride contains lithium chloride in a range of 20% to 40% by mass based on the total mass of the aqueous solution of lithium chloride. <8> A humidity control method that uses a humidity control liquid described in any one of <1> to <4>. <9> A humidity control device comprising a humidity control section that brings the humidity control liquid described in any one of <1> to <4> into contact with air. <10> The humidity control device according to <9>, wherein at least a portion of the part that comes into contact with the humidity control liquid contains copper.

[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.

[0010] This is an explanatory diagram illustrating the configuration of a liquid desiccant air conditioner. The graph shows the relationship between elapsed time (hours) and the weight ratio of the tubes in the examples and comparative examples.

[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, numerical ranges indicated using "~" mean a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this specification, the upper or lower limit stated in one numerical range may be replaced with the value shown in the 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, the amount of each component means the total amount of multiple substances if there are multiple substances corresponding to each component, unless otherwise specified. In this disclosure, "room temperature" means 25°C.

[0013] <Humidity Control Liquid> A humidity control liquid, which is one embodiment of the present disclosure, comprises lithium chloride, water, a water-soluble rust inhibitor, and an ionic liquid. In one embodiment of the present disclosure, the lithium chloride and a portion of the water contained in the humidity control liquid are based on an aqueous lithium chloride solution used in the production of the humidity control liquid, and the ionic liquid and a portion of the water are based on an aqueous ionic liquid solution used in the production of the humidity control liquid.

[0014] Dehumidifying solutions containing lithium chloride aqueous solution are preferred for use in dehumidifying devices such as liquid desiccant air conditioners due to their high dehumidifying performance, antibacterial properties, and the fact that lithium chloride does not vaporize, making them a stable substance. Specifically regarding dehumidifying performance, dehumidifying solutions containing lithium chloride aqueous solution allow for precise control of the water vapor pressure of the contacting air by combining temperature and lithium chloride concentration, making it possible to obtain air at the desired temperature and humidity. In particular, since it is not necessary to cool the air to the desired dew point temperature during dehumidification, the temperature of the cooling source can be raised compared to general cooling dehumidification methods, resulting in superior energy efficiency.

[0015] However, because lithium chloride aqueous solutions are highly corrosive to metals, in humidity control devices that use a humidity control solution containing lithium chloride aqueous solution, if the parts that come into contact with the humidity control solution contain metal, it was necessary to take measures such as using a metal that is resistant to the lithium chloride aqueous solution, such as titanium.

[0016] The inventors investigated reducing the corrosiveness to metals by adding a rust inhibitor to the humidity control solution, in order to enable the use of inexpensive, general-purpose metals, mainly copper, in the metal parts of humidity control devices that come into contact with the humidity control solution containing an aqueous lithium chloride solution. However, when a water-soluble rust inhibitor, which is said to be able to reduce the corrosiveness to copper, was added to the aqueous lithium chloride solution, it was found that at room temperature, such as 25°C, the water-soluble rust inhibitor hardly dissolved in the aqueous lithium chloride solution, and even when the water-soluble rust inhibitor was dissolved at high temperatures, it sometimes precipitated out as the temperature decreased.

[0017] Therefore, in order to create a humidity control solution that reduces corrosiveness while maintaining high humidity control performance, further investigation was conducted into adding a water-soluble rust inhibitor to an aqueous lithium chloride solution. It was found that the water-soluble rust inhibitor is easily compatible with the aqueous lithium chloride solution in the presence of an ionic liquid. Furthermore, it was found that a humidity control solution obtained by mixing an ionic liquid containing a dissolved water-soluble rust inhibitor with an aqueous lithium chloride solution significantly reduces corrosiveness, particularly to copper and copper alloys, while also possessing high humidity control performance.

[0018] Although the mechanism by which the above effects are achieved is not clear, it is speculated that the water-soluble rust inhibitor dispersed in the lithium chloride aqueous solution by the presence of an ionic liquid functions appropriately within the system and forms a film on metals such as copper or copper alloys, thereby imparting a reduced corrosive effect on the metal from the lithium chloride aqueous solution.

[0019] (Lithium Chloride Aqueous Solution) The humidity control solution contains lithium chloride and water. Lithium chloride is used as a humidity control agent because it is hygroscopic. One type of humidity control agent may be used, or two or more types may be used. The humidity control solution, which contains the humidity control agent and water, controls the vapor pressure of the vapor-liquid equilibrium by controlling the concentration, thereby controlling the humidity of the air. For example, if the humidity of the air is high, the concentration of the humidity control agent in the humidity control solution is increased by heating the humidity control solution to evaporate the water, and the humidity is lowered by the concentrated humidity control agent absorbing moisture from the air. On the other hand, if the humidity of the air is low, the concentration of the humidity control agent in the humidity control solution is lowered by supplying water to the humidity control solution, and the humidity is raised by the lower-concentration humidity control solution adding moisture to the air.

[0020] In addition to lithium chloride, other metal halides such as lithium bromide and calcium chloride can be used as humidity control agents. Aqueous solutions of lithium chloride have a disinfecting effect, do not vaporize, and are stable and safe substances; therefore, lithium chloride is preferred as a humidity control agent. Ionic liquids or aqueous solutions of ionic liquids can also be used as humidity control agents. Ionic liquids will be discussed 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 H.H. Urick and R.W. 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, etc., and benzotriazole is more preferred in particular because it has a high rust-preventive effect on copper. Note that one type of water-soluble rust inhibitor may be used, or two or more types may be mixed and used.

[0026] (Ionic Liquid Aqueous Solution) The humidity control solution 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 environment in which it is used. It is preferable to use the ionic liquid as an aqueous solution of the ionic liquid mixed with water. 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 have excellent water absorption and release performance when used as a humidity control liquid. The above 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 performance. 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 preferable humidity control performance. In this specification, "water absorption and release properties" includes "hygroscopicity" and means 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 disinfectant properties. It is preferable that the ionic liquid has disinfectant properties and that the disinfectant properties are not impaired in a humidity control liquid mixed with an aqueous lithium chloride solution.

[0028] The viscosity of the ionic liquid, etc., is preferably such that it has adequate 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 in 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 methyl sulfonate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1,3-dimethylimidazolium propionate, etc., can be suitably used. Note that 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 additives include a water-soluble rust inhibitor, an ionic liquid, and water. In the additives, the ionic liquid and water are based on an aqueous solution of the ionic liquid. That is, the additives include an aqueous solution of the ionic liquid and a water-soluble rust inhibitor. The additives are added to an aqueous solution of lithium chloride prepared from lithium chloride and water. By adding the additives to the aqueous solution of lithium chloride, it becomes possible to mix the aqueous solution of lithium chloride and the water-soluble rust inhibitor while suppressing the precipitation of the water-soluble rust inhibitor, thereby imparting a corrosiveness-reducing effect to the aqueous solution of lithium chloride. Note that 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 ionic liquid aqueous solution. The amount of water-soluble rust inhibitor used in the total humidity-conditioning 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 / desorption or humidity control performance of lithium chloride, the proportion of additives can be such that the lithium chloride aqueous solution is the main component and the additives are present 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 solution, the temperature at which the humidity control solution is used, the type of humidity control device using the humidity control solution, etc.

[0037] (Other Components) The humidity control liquid may contain other components besides lithium chloride, water, a water-soluble rust inhibitor, and the components 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. The specific other components are not limited, but examples include known additives such as flame retardants, colorants, defoamers, viscosity modifiers, and pH adjusters. Other components in the humidity control liquid may be used insofar as they do not impair the effectiveness of the humidity control liquid.

[0038] <Method for producing humidity control liquid> One embodiment of the method for producing humidity control liquid according to the present disclosure 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, it is possible to suppress the precipitation of benzotriazole 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 the method for manufacturing a humidity control liquid which is an embodiment of the present disclosure, it is possible to provide a humidity control liquid that reduces the corrosiveness to metals such as copper and copper alloys. For example, the main material of most heat exchangers is copper, and even when the main material is other than copper, since the workability, corrosion resistance, thermal conductivity, etc. are good, brazing materials and the like often contain copper. Therefore, since it is possible to use a humidity control liquid composed of an aqueous lithium chloride solution, which is suitable as a humidity control liquid, for heat exchangers that are generally widely used, the range of use of the humidity control liquid containing an aqueous lithium chloride solution can be greatly expanded. For this reason, many parts used in air conditioners are made of copper or copper alloys, and the value of a liquid humidity control agent that does not corrode copper is very high.

[0043] (Additive adjustment step) The method for manufacturing a humidity control liquid includes an additive adjustment step of preparing an additive by mixing an ionic liquid aqueous solution containing an ionic liquid and water and a water-soluble rust inhibitor.

[0044] In the additive adjustment step, an ionic liquid aqueous solution and a water-soluble rust inhibitor are each prepared and mixed. In the additive adjustment step, there are no particular restrictions on the method of mixing the ionic liquid aqueous solution and the water-soluble rust inhibitor, and the two may be mixed by a conventionally known method.

[0045] In the additive adjustment step, for example, various operations such as heating and stirring may be performed in the mixing of the ionic liquid aqueous solution and the water-soluble rust inhibitor.

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

[0047] In the mixing step, an ionic liquid aqueous solution containing an ionic liquid, water, and a water-soluble rust inhibitor, and an aqueous lithium chloride solution containing lithium chloride and water are each prepared and mixed. In the mixing step, there are no particular restrictions on the method of mixing the ionic liquid aqueous solution and the aqueous lithium chloride solution, and the two may be mixed by a conventionally known method.

[0048] Incidentally, in the mixing step, for example, various operations such as heating and stirring, which have been conventionally performed on an aqueous lithium chloride solution, an ionic liquid aqueous solution, etc., may be carried out. Incidentally, in the method for producing the humidity conditioning liquid, the preferable usage amounts of the respective components and the like are the same as those described for the above humidity conditioning liquid.

[0049] <Humidity Conditioning Method> The humidity conditioning method according to an embodiment of the present disclosure performs humidity conditioning using the above humidity conditioning liquid. By using the above humidity conditioning liquid, air can be humidity-conditioned with excellent energy efficiency and good humidity controllability.

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

[0051] By using the humidity conditioning method according to an embodiment of the present disclosure, the concentration of the humidity conditioning agent contained in the humidity conditioning liquid can be adjusted by a conventionally known method, and humidity conditioning can be suitably performed. Incidentally, the humidity conditioning method may be performed while also performing ventilation.

[0052] <Humidity Conditioning Device> An embodiment of the present disclosure is a humidity conditioning device including a humidity conditioning unit that brings the humidity conditioning liquid according to an embodiment of the present disclosure into contact with air. The humidity conditioning unit is a means for exerting a humidity conditioning function for adjusting the humidity of the taken-in air.

[0053] Specifically, the humidity conditioning unit can employ means capable of bringing the humidity conditioning liquid into contact with air, and can use various conventionally known means. For example, means for supplying the humidity conditioning liquid from the upper part to the lower part of the processing machine and passing the taken-in air through the inside of the processing machine can be used.

[0054] Further, the humidity conditioning unit may also have a temperature conditioning function for adjusting the temperature of the taken-in air. The temperature conditioning function can be achieved, for example, by adjusting the temperature of the humidity conditioning liquid in the humidity conditioning 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 unit 20 takes in air from the air intake port 21 and discharges the treated air from the exhaust port 22. The processing unit 20 is equipped with a humidity control liquid 23 and a gas-liquid contactor 24 inside. The processing unit 20 is also equipped with a humidity control liquid outlet 25 and a humidity control liquid supply port 26, and the adjusted humidity control liquid 23 is supplied to the upper part of the gas-liquid contactor 24, 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 25 and supplied to the regenerator 30 via the heat exchanger 41.

[0058] The regenerator 30 takes in air from the air intake port 31 and discharges the treated air from the exhaust port 32. The regenerator 30 is equipped with a humidity control liquid 33 and a gas-liquid contactor 34 inside. The regenerator 30 is also equipped with a humidity control liquid outlet 35 and a humidity control liquid supply port 36, and the adjusted humidity control liquid 33 is supplied to the upper part of the gas-liquid contactor 34, 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.

[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 for metals was evaluated using the obtained humidity control solution. The results are shown in Table 1.

[0062] [Example] <Preparation 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. For the entire humidity control solution A (400 ml) containing 20 ml of additive A and 380 ml of lithium chloride aqueous solution, an amount of benzotriazole to make a concentration of 0.04 M (mol / L) was mixed with 20 ml of CreCOPlus, 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 lithium chloride concentration of 30% by mass.

[0064] (Preparation of humidity control solution 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] <Evaluation> Corrosion tests were conducted on humidity control liquid A and humidity control liquid B as described below, and the amount of corrosion in the humidity control liquid at each time interval was evaluated.

[0067] =Corrosion Test= The corrosion test was conducted by placing 400 mL of humidity control solution A into a lidded bottle, maintaining the temperature at 45°C, and stirring humidity control 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 point in time, the tube was removed and its weight was measured. After measuring the weight, the tube was immersed again in the humidity-controlled solution. The weight of the tube was measured a total of 11 times, from before immersion to approximately 3000 hours later.

[0069] The elapsed time from the start of immersion was recorded, and the weight was measured and recorded at regular intervals. When measuring the weight, any compound residue was removed, washed with pure water, and thoroughly dried. Initially, a small amount of verdigris-like residue was observed where the nylon thread had been in contact, and this was removed, but no residue was observed thereafter. This is why a relatively large weight decrease was observed during the first weight measurement. The humidity control solution A is an almost colorless and transparent liquid, and no visible changes were observed during the test. Furthermore, 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 appearance of the copper tube was slightly darkened, but the copper luster characteristic of the addition of benzotriazole was maintained.

[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 time of 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 the weight ratio, which showed that the weight of the tube hardly changed from approximately 200 hours to approximately 3000 hours.

[0071] As described above, a corrosion test was conducted on humidity control solution A. In addition, 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. After 24 hours, the liquid in humidity control solution B, which was initially almost colorless and transparent, had become cloudy with a verdigris color, indicating that corrosion was progressing rapidly. When the appearance of the copper tube was observed, no deposits were found, but it had completely lost its luster, suggesting that corrosion had progressed throughout the entire tube. The elapsed time (in hours) and the weight of the tube were measured, and the weight ratio and weight loss rate were calculated with the weight at the first measurement set to 1 and recorded in Table 1. If the test was not performed, it is indicated as blank in Table 1.

[0072]

[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 for 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.

[0074] The disclosure of Japanese Patent Application No. 2024-157852, filed on 11 September 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

[0075] 10 Liquid desiccant air conditioner 20 Processing unit 21 Air intake 22 Exhaust 23 Dehumidifying liquid 24 Gas-liquid contactor 25 Dehumidifying liquid outlet 26 Dehumidifying liquid supply port 30 Regenerator 31 Air intake 32 Exhaust port 33 Dehumidifying liquid 34 Gas-liquid contactor 35 Dehumidifying liquid outlet 36 Dehumidifying 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 a humidity control liquid according to claim 1, wherein the ionic liquid has water absorption and release properties.

4. The humidity control liquid according to claim 1, wherein the ionic liquid comprises imidazolium.

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 method for producing a humidity control liquid according to claim 5, wherein the additive is mixed in an amount of 1% 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 method for controlling humidity using the humidity control liquid described in 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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