JP2012255080A - Heat storage agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a latent heat storage agent in which a heat storage speed is improved by preventing supercooling, and the separation of an addition component can be controlled.SOLUTION: The heat storage agent comprises a clathrate hydrate that is generated by cooling an aqueous solution containing tetra-n-butylammonium bromide as a solute, and is characterized in that the heat storage agent is prepared by adding tetra-iso-pentylammonium bromide, an alkali metal phosphate, and a cellulose derivative to the aqueous solution, and the cellulose derivative comprises at least one of a carboxyl group and a carboxymethyl group, or comprises at least one of a carboxyl group and a carboxymethyl group together with an alkali metal.

Description

  The present invention relates to a latent heat storage agent, and more particularly to a technique for preventing overcooling to increase a heat storage rate and suppressing separation of additive components.

  As the heat storage agent used as the main agent of the heat storage agent, the heat storage amount per unit time (hereinafter referred to as “heat storage speed”) is preferably as high as practical. This is because if the heat storage speed is higher, more heat energy can be stored in a shorter time.

  The clathrate hydrate of tetra nbutylammonium bromide (including quasi clathrate hydrate, including quasi clathrate hydrate) produced by cooling an aqueous solution of tetra nbutylammonium bromide (hereinafter referred to as “raw aqueous solution”) is It is well known as a heat storage agent used for heat storage type building air-conditioning equipment and a main ingredient of a cold storage material for preserving fresh fish (for example, see Patent Documents 1 and 2), and is also known to be difficult to cause phase separation. (For example, refer to Patent Document 3). And the amount of heat storage per unit time when the clathrate hydrate of tetra nbutylammonium bromide is produced from the raw material aqueous solution (this is because the clathrate hydrate of tetra nbutylammonium bromide returns to the raw material aqueous solution. The amount of heat released per unit time is substantially equal), that is, technology development for increasing the heat storage speed is underway.

  In addition, when the aqueous solution of the raw material is cooled to produce a hydrate of tetra-n-butylammonium bromide, no hydrate is produced even when the temperature is lower than the hydrate production temperature, and the solution state is at least temporarily. Is maintained, that is, a supercooling phenomenon occurs. This phenomenon delays the formation and growth of hydrate crystals, and generally reduces the heat storage rate of the heat storage agent. Therefore, in order to avoid the decrease in the heat storage rate or increase the heat storage rate, a technique for preventing or suppressing the supercooling of the raw material aqueous solution is required. As such a technique, there is a technique for improving the heat storage rate by adding an alkali metal phosphate to a raw material aqueous solution (see, for example, Patent Document 4).

JP 2001-280875 A JP 2007-161894 A Japanese Patent Laying-Open No. 2005-126728 JP 2008-214527 A JP 2006-131856 A Japanese Patent No. 3774530

  Even if the effect of preventing supercooling occurs by adding a supercooling inhibitor to the raw material aqueous solution, in the actual usage environment of the heat storage agent, heat storage and heat dissipation (hereinafter collectively referred to as “storage heat dissipation”) The clathrate hydrate formation or solidification and melting is frequently repeated. Such repeated heat storage and heat dissipation may cause deterioration of the supercooling prevention effect of the supercooling preventive agent over time. Therefore, in a heat storage agent composed mainly of an aqueous solution of tetra-n-butylammonium bromide, supercooling can be released in a short time, that is, heat can be stored in a short time, heat storage speed is increased, and heat storage and heat release are frequently performed. Therefore, there is a need for an anti-cooling agent that can realize that the anti-cooling effect does not deteriorate over time even if it is repeated.

  Moreover, in order to prevent the overcooling of the clathrate hydrate of tetra n-butylammonium bromide produced from the raw material aqueous solution and maintain the effect of improving the heat storage rate, an alkali metal phosphate is used as the supercooling inhibitor. It has also been confirmed that when a large amount is added to the alkali metal phosphate, the alkali metal phosphate is precipitated and phase separation occurs due to the precipitation.

  On the other hand, the following example is known as a technique for preventing or suppressing phase separation caused by the heat storage agent.

  (1) A method of using a polysaccharide such as starch to suppress phase separation of a heat storage agent mainly composed of sodium sulfate decahydrate (Patent Document 5). According to this method, phase separation can be prevented or suppressed by the physical effect of gelation of the heat storage agent using polysaccharides such as starch.

  (2) A technique in which a thickener is added in order to suppress sedimentation of the supporting crystals for preventing overcooling contained in the heat storage agent mainly composed of sodium acetate trihydrate (Patent Document 6). According to this technique, due to the physical effect of viscosity increase by the thickener, sedimentation of the supercooling-preventing supported crystals is suppressed, and phase separation caused by the sedimentation can be prevented or suppressed.

  However, in order to maintain the physical effects in the above methods (1) and (2), the viscosity of the heat storage agent must be significantly increased. In order to greatly increase the viscosity of the heat storage agent, it is necessary to add a large amount of polysaccharides and thickeners, so the ratio of tetra-n-butylammonium bromide, which is the main component of the heat storage agent, decreases relatively. The performance problem that a heat storage amount falls arises.

  The present invention has been made in view of the above circumstances, and an aqueous solution for clathrate hydrate generation (raw material aqueous solution) containing tetra-n-butylammonium bromide as a solute is cooled below the hydrate formation temperature. In the heat storage agent containing the clathrate hydrate produced by this, when the clathrate hydrate is produced by cooling the raw material aqueous solution, the degree of supercooling of the raw material aqueous solution is reduced or the supercooling is prevented or suppressed. In addition, the heat storage rate can be increased, and even if hydrate formation or solidification and melting in the raw material aqueous solution is repeated frequently, the effect of preventing overcooling can be made difficult to occur, and supercooling can be prevented. An object is to provide a heat storage agent that prevents sedimentation of the inhibitor and has a large amount of heat storage.

  In the present invention, an alkali metal phosphate is added together with tetraisopentylammonium bromide as a supercooling inhibitor to an aqueous solution for clathrate hydrate formation containing tetra-n-butylammonium bromide as a solute. By using both tetraisopentylammonium bromide and alkali metal phosphate as a supercooling inhibitor, supercooling is released in a short time, that is, heat can be stored in a short time, and the heat storage speed is improved. In addition, it is possible to provide a heat storage agent that does not deteriorate over time in the effect of preventing overcooling even if heat storage and heat dissipation are frequently repeated.

  On the other hand, an aqueous solution for clathrate hydrate production containing tetra-n-butylammonium bromide as a solute is cooled to a heat storage agent containing clathrate hydrate produced by cooling below the hydrate production temperature. When alkali metal phosphate was added to a specific concentration or more as an inhibitor, a phenomenon that the alkali metal phosphate settled was observed.

  Therefore, as a result of intensive studies by the present inventors, clathrate water produced by cooling an aqueous solution for clathrate hydrate production containing tetra-n-butylammonium bromide as a solute below the hydrate formation temperature. A cellulose derivative having at least one of a carboxyl group and a carboxymethyl group is added to a heat storage agent containing a hydrate and an alkali metal phosphate, or at least one of a carboxyl group and a carboxymethyl group is added and an alkali It has been found that by adding a cellulose derivative having a metal as well, precipitation of alkali metal phosphate can be suppressed and a large amount of heat storage can be provided.

  This is not simply a physical action such as an increase in viscosity, but a chemical action of an alkali metal phosphate and a cellulose derivative having at least one of a carboxyl group and a carboxymethyl group, or a carboxyl group and a carboxy group. It is considered that precipitation of alkali metal phosphate can be suppressed by a chemical action with a cellulose derivative having at least one methyl group and having an alkali metal. Further, the present inventor has found that even when these cellulose derivatives are added, the performance of the heat storage agent, that is, the supercooling release performance and the heat storage speed are not impaired to a problem.

  Furthermore, the inventor of the present invention is an aqueous solution for producing clathrate hydrate containing tetra-n-butylammonium bromide as a solute, which is added to an aqueous solution containing tetraisopentylammonium bromide and alkali metal phosphate. Although the viscosity of the aqueous solution to be purified varies depending on the molecular weight and addition amount of the cellulose derivative, it has been found that the effect of inhibiting the precipitation of alkali metal phosphate has little relation to the viscosity. Therefore, since precipitation of alkali metal phosphate can be suppressed without significantly increasing the viscosity of an aqueous solution containing tetra nbutylammonium bromide, tetraisopentylammonium bromide and alkali metal phosphate, It is possible to avoid problems in handling such that it becomes difficult to fill the heat storage container with the heat storage container due to the viscosity.

  The present invention is based on each of the above findings. Among them, the heat storage agent according to the first embodiment of the present invention has an aqueous solution containing tetra-n-butylammonium bromide as a solute cooled to a hydrate formation temperature or lower. A heat storage agent containing clathrate hydrate formed by adding tetraisopentylammonium bromide, alkali metal phosphate and cellulose derivative to the aqueous solution, wherein the cellulose derivative is carboxylated A cellulose derivative having at least one of a group and a carboxymethyl group, or a cellulose derivative having at least one of a carboxyl group and a carboxymethyl group and an alkali metal.

  The heat storage agent according to the second embodiment of the present invention is the heat storage agent according to the first embodiment, and the concentration of tetra n-butyl ammonium bromide in the aqueous solution containing tetra n-butyl ammonium bromide as a solute is 20% by weight or more. 40.5% by weight or less, and the weight ratio of tetraisopentylammonium bromide to an aqueous solution containing tetra-n-butylammonium bromide as a solute is 0.1% to 7.0%. It is.

The heat storage agent according to the third embodiment of the present invention is the heat storage agent according to the first embodiment, and is a solution of tetraisopentylammonium bromide (TiPAB) with respect to an aqueous solution containing tetra-n-butylammonium bromide (TBAB) as a solute. The weight ratio corresponds to the TBAB concentration which is the weight concentration of tetra nbutylammonium bromide (TBAB) in the aqueous solution containing tetra nbutylammonium bromide (TBAB) as a solute,
When the TBAB concentration is 15% by weight or more and less than 20% by weight, the weight ratio is 0.1% or more and 3.0% or less,
When the TBAB concentration is 20% by weight or more and less than 25% by weight, the weight ratio is 0.1% or more and 7.0% or less,
When the TBAB concentration is 25% by weight or more and less than 30% by weight, the weight ratio is 0.1% or more and 12.0% or less,
When the TBAB concentration is 30% by weight or more and less than 35% by weight, the weight ratio is 0.1% or more and 9.0% or less,
When the TBAB concentration is 35% by weight or more and 40.5% by weight or less, the weight ratio is 0.1% or more and 8.0% or less.

  A heat storage agent according to a fourth embodiment of the present invention is the heat storage agent according to any one of the first to third embodiments, wherein the alkali metal phosphate is disodium hydrogen phosphate. It is.

  The heat storage agent according to the fifth embodiment of the present invention is the heat storage agent according to the fourth embodiment, and the concentration of tetra-n-butylammonium bromide in the aqueous solution containing tetra-n-butylammonium bromide as a solute is 15% by weight or more. 40.5% by weight or less, and the weight ratio of disodium hydrogen phosphate to an aqueous solution containing tetra-n-butylammonium bromide as a solute is 0.1% or more and 7.0% or less. is there.

The heat storage agent according to the sixth embodiment of the present invention is the heat storage agent according to the fourth embodiment, wherein the weight ratio of disodium hydrogen phosphate to the aqueous solution containing tetra-n-butylammonium bromide (TBAB) as a solute, Corresponding to the TBAB concentration, which is the weight concentration of tetra nbutylammonium bromide (TBAB) in an aqueous solution containing tetra nbutylammonium bromide as the (TBAB) solute,
When the TBAB concentration is 15% by weight or more and less than 20% by weight, the weight ratio is 0.1% or more and 8.0% or less,
When the TBAB concentration is 20% by weight or more and less than 25% by weight, the weight ratio is 0.1% or more and 10.0% or less,
When the TBAB concentration is 25% by weight or more and less than 30% by weight, the weight ratio is 0.1% or more and 11.0% or less,
When the TBAB concentration is 30% by weight or more and less than 35% by weight, the weight ratio is 0.1% or more and 9.0% or less,
When the TBAB concentration is 35% by weight or more and 40.5% by weight or less, the weight ratio is 0.1% or more and 7.0% or less.

  A heat storage agent according to a seventh aspect of the present invention is the heat storage agent according to any one of the first to sixth aspects, and includes at least one of the carboxyl group and the carboxymethyl group, and an alkali metal. The cellulose derivative is sodium carboxymethylcellulose.

  The heat storage agent according to the eighth embodiment of the present invention is the heat storage agent according to the seventh embodiment, wherein the weight ratio of sodium carboxymethylcellulose to the aqueous solution containing tetra-n-butylammonium bromide as a solute is 0.1% or more. It is characterized by being 10.0% or less.

  In the heat storage agent according to each aspect of the present invention, typical examples of the cellulose derivative having at least one of a carboxyl group and a carboxymethyl group are carrageenan and carboxymethylcellulose. Further, typical examples of the cellulose derivative having at least one of a carboxyl group and a carboxymethyl group and having an alkali metal are sodium carboxymethyl cellulose and sodium alginate. Typical examples of alkali metal phosphates are sodium phosphate, potassium phosphate, specifically sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, potassium dihydrogen phosphate. , Dipotassium hydrogen phosphate, tripotassium phosphate, or a mixture thereof.

  In the present specification, the following terms are interpreted as follows unless otherwise explained.

  (1) The “clathrate hydrate” includes quasi clathrate hydrate.

  (2) The “clathrate hydrate” is sometimes abbreviated as “hydrate”.

  (3) “Raw material aqueous solution” is an aqueous solution for clathrate hydrate formation containing tetra-n-butylammonium bromide as a solute, and tetraisopentylammonium bromide, alkali metal phosphate and cellulose derivative are added. Refers to an aqueous solution. Even if a trace amount substance other than tetra-n-butylammonium bromide, tetraisopentylammonium bromide, alkali metal phosphate and cellulose derivative is added, it is referred to as “raw aqueous solution”. Moreover, even if the clathrate hydrate containing tetra-n-butylammonium bromide as a guest compound is dispersed or suspended, an aqueous solution containing tetra-n-butylammonium bromide is referred to as “raw aqueous solution”.

  (4) “Hydrate formation temperature” refers to an equilibrium temperature at which clathrate hydrates containing tetra-n-butylammonium bromide as a guest compound are generated when the raw material aqueous solution is cooled. Even when the temperature at which the clathrate compound is generated varies depending on the concentration of tetra-n-butylammonium bromide in the raw material aqueous solution, this is referred to as “hydrate formation temperature”. For convenience, the “hydrate formation temperature” may be referred to as “freezing point”.

  (5) “The clathrate hydrate containing tetra-n-butylammonium bromide as a guest compound” may be abbreviated as “tetra-n-butylammonium bromide hydrate”.

  (6) “Heat storage agent” refers to a substance having a heat storage property regardless of the purpose and mode of use, storage, and other uses of thermal energy. Substances having cold storage properties are sometimes referred to as “cold storage agents”. The clathrate hydrate having heat storage properties can be a constituent of “heat storage agent” or “cold storage agent”.

  (7) “Heat storage rate” refers to the amount of heat energy that a heat storage agent of unit volume or unit weight can store in a unit time by a heat exchange operation under a certain condition, or a parameter having a positive correlation with this.

(8) “Harmonic melting point” refers to the case where the composition before and after the phase change from an aqueous solution (liquid phase) to a hydrate (solid phase) does not change when a hydrate is formed by cooling the raw aqueous solution (for example, Temperature when the hydrate having the same guest molecule concentration as that of the original aqueous solution is cooled and formed. Although the temperature (melting point) at which clathrate hydrate is generated varies depending on the concentration of guest molecules in the aqueous solution, the maximum point is the harmonic melting point in the state diagram in which the vertical axis indicates the melting point temperature and the horizontal axis indicates the concentration.

  According to the present invention, in a heat storage agent containing an clathrate hydrate produced by cooling an aqueous solution for clathrate hydrate production containing tetra-n-butylammonium bromide as a solute to a hydrate production temperature or lower. By the action of tetraisopentylammonium bromide and alkali metal phosphate added, the supercooling degree of the raw material aqueous solution can be reduced or supercooling can be prevented or suppressed, and the heat storage rate can be high, and solidification and melting can be achieved. It is possible to maintain a high heat storage rate even if the process is repeated, and it has a cellulose derivative having at least one of a carboxyl group and a carboxymethyl group, or at least one of a carboxyl group and a carboxymethyl group, and an alkali metal. Effective addition of alkali metal phosphate sedimentation by adding cellulose derivatives It is possible to provide a heat storage agent that door can be.

  According to the present invention, since tetraisopentylammonium bromide and alkali metal phosphate are added to an aqueous solution containing tetra-n-butylammonium bromide as a solute, a heat storage agent or a hydrate as its main component is obtained. When it is generated by cooling the aqueous solution, overcooling can be prevented or suppressed. Here, the tetraisopentylammonium bromide and the alkali metal phosphate are such that the weight ratio of the tetraisopentylammonium bromide or the alkali metal phosphate to the aqueous solution containing tetra-n-butylammonium bromide as a solute is within a predetermined range. Therefore, the reduction in latent heat amount in the temperature range of 3 to 15 ° C, which is excellent when using a heat storage agent for air conditioning applications, is within a practical fluctuation allowable range. can do. Moreover, even if the production | generation of a hydrate in raw material aqueous solution or coagulation | solidification and melting | fusing is repeated frequently, the fall of a supercooling prevention effect can be made hard to occur.

  Therefore, according to the present invention, the effect of preventing the supercooling is reduced even if the heat storage agent having a reduced supercooling degree or hardly causing supercooling, or the frequent formation and solidification and melting of hydrates is repeated. It is possible to realize a heat storage agent that hardly occurs.

  In addition, by adding the above cellulose derivative, the precipitation of alkali metal phosphate can be effectively suppressed, and the ratio of tetra-n-butylammonium bromide that is the main component of the heat storage agent is not reduced. Therefore, the problem that the amount of stored heat decreases does not occur.

  The heat storage agent according to the present invention has a high supercooling prevention effect, a high heat storage rate, and can maintain the supercooling prevention effect even when the hydrate formation or solidification and melting are repeated frequently. A large amount of cold energy can be accumulated in the temperature range of 15 ° C., and precipitation of alkali metal phosphate can be prevented. For this reason, the heat storage agent according to the present invention is particularly promising as a heat storage agent for air conditioning.

  The reason why the latent heat storage agent capable of storing heat in the temperature range of 3 to 15 ° C. is suitable for air conditioning applications is as follows.

  That is, in air conditioning using a latent heat storage agent, heat exchange between the heat storage agent storing the cold heat from the cold source as latent heat and the air of the air conditioning load is performed directly or through a medium, and the air after the heat exchange is air-conditioned. By sending it to the target space, the temperature and humidity of the space are adjusted. In many cases, the temperature of the cold air blown out from the indoor unit in the cooling air-conditioning is generally about 15 ° C., and at most about 17 ° C. If the temperature is higher than that, it is difficult to obtain the same level of air-conditioning effect unless the amount of air to be sent out toward the space to be air-conditioned is increased. On the contrary, the air-conditioning efficiency is lowered. Therefore, the latent heat storage agent that supplies cold heat to cold air is required to be capable of storing latent heat of 15 ° C. or less in consideration of a temperature difference (about 2 ° C.) necessary for heat exchange with air. . In addition, in the case of ice, which is a typical example of a latent heat storage agent for air conditioning, it is necessary to cool at a temperature lower than 0 ° C., so the COP of the refrigerator becomes low, the energy required for cold storage increases, and energy saving cannot be achieved. There is a problem. In order to maintain COP at a high level and realize energy saving, the latent heat storage agent for air conditioning is required to be capable of storing heat at a temperature higher than 0 ° C., more preferably at 3 ° C. or higher. Therefore, the latent heat storage agent that can store heat in the temperature range of 3 to 15 ° C. is suitable for air conditioning applications.

  However, a heat storage agent capable of storing thermal energy in the temperature range of 3 to 15 ° C. must be able to withstand actual use regardless of whether it is used for air conditioning.

  For example, there is a heat storage agent (melting point: 10 to 25 ° C.) in which polyglycerin is added to a hydrate-based heat storage agent main component containing trimethylolethane, water, and urea. This heat storage agent is described in detail in Japanese Patent Application Laid-Open No. 2000-256659, but as long as it is described, the number of times of confirming the repetition of solidification and melting is limited to about 100 at most. With this number of repeated uses, the purpose of use is limited, and the effect of preventing overcooling can occur if separation of component substances in the aqueous solution, concentration deviation, or phase separation between the hydrate formed by cooling and the parent phase occurs. It is difficult to say that it can withstand widespread actual use (especially for private use).

  On the other hand, in the heat storage agent according to the present invention, tetraisopentylammonium bromide, alkali metal phosphate, and cellulose derivative are added to an aqueous solution of tetra-n-butylammonium bromide. Tetra-n-butylammonium bromide accumulates thermal energy corresponding to latent heat in a temperature range of 3 to 15 ° C. when in an aqueous solution state. The hydrate formation temperature does not change greatly even when a small amount of tetraisopentylammonium bromide, alkali metal phosphate and cellulose derivative are added. When the clathrate hydrate is produced from the raw material aqueous solution containing tetraisopentylammonium bromide, alkali metal phosphate and cellulose derivative as additives, the degree of supercooling of the raw material aqueous solution is reduced or prevented from being overcooled. Alternatively, it is suppressed and a high heat storage rate can be obtained. And even if it repeats generation | occurrence | production of a hydrate or coagulation | solidification and melting | dissolving 1000 times or more in the said raw material aqueous solution, the effect of supercooling prevention does not fall, and a high heat storage rate can be maintained.

  Therefore, according to the present invention, it is possible to accumulate heat energy in a temperature range of 3 to 15 ° C. suitable for air conditioning applications, and to achieve a particularly beneficial effect that a heat storage agent that can withstand practical use can be realized.

  Hereinafter, the present invention will be described in detail by embodiments. For convenience, tetra-n-butylammonium bromide is sometimes abbreviated as “TBAB”, and tetraisopentylammonium bromide is sometimes abbreviated as “TiPAB”.

  1. New knowledge related to the present invention will be described. Some forms of the invention are based on this new knowledge.

  (A) Regarding a heat storage agent containing a clathrate hydrate containing tetra nbutylammonium bromide as a guest molecule (particularly a heat storage agent containing the clathrate hydrate as a main component), tetra nbutylammonium bromide as a solute The substance which can exhibit or maintain the effect of preventing or suppressing the supercooling generated when the raw material aqueous solution containing it is cooled and its blending composition are studied, and tetraisopentylammonium bromide and alkali metal phosphate as the substance It is effective to add together and further, a substance capable of effectively suppressing the precipitation of alkali metal phosphate and the composition of the substance are studied, and a cellulose derivative may be added as the substance. I found it effective.

  The reason why the effect of preventing overcooling is estimated by adding tetraisopentylammonium bromide to a raw material aqueous solution containing tetra-nbutylammonium bromide as a solute is as follows.

  That is, tetraisopentylammonium bromide has a hydrate harmonic melting point of 28 ° C., and the freezing point of a hydrate produced from a raw material aqueous solution containing tetra-n-butylammonium bromide as a solute or tetra-n-butylammonium bromide water. It is sufficiently higher than the freezing point of Japanese products. Therefore, when the raw material aqueous solution is cooled, tetraisopentylammonium bromide hydrate is formed before tetranbutylammonium bromide hydrate. Then, the tetraisopentylammonium bromide hydrate becomes a nucleus (product nucleus) that triggers or induces the formation of tetra-n-butylammonium bromide hydrate. As a result, the overcooling is prevented or suppressed. Tetraisobutylammonium bromide hydrate is a related substance of tetra-n-butylammonium bromide hydrate and is compatible and has similar crystal structure. It tends to be a product nuclei, and supercooling is effectively prevented or suppressed.

  In order to prevent overcooling of aqueous solution of tetra nbutylammonium bromide, tetraisopentylammonium bromide and alkali metal phosphate are added together as a supercooling inhibitor to prevent overcooling more effectively. can do. Alkali metal phosphates, like tetraisopentylammonium bromide, form nuclei of tetra-n-butylammonium bromide hydrate and prevent overcooling. For example, when tetraisopentylammonium bromide is added to an aqueous solution of tetra-n-butylammonium bromide, an alkali metal phosphate is added to the aqueous solution of tetra-n-butylammonium bromide, and tetraisopentylammonium bromide is added. If used together, the effect of preventing overcooling is enhanced as compared with the case where only tetraisopentylammonium bromide is added. Therefore, according to this combined use, even if the addition rate of tetraisopentylammonium bromide is reduced, the same level of supercooling prevention effect can be obtained, and due to the addition of tetraisopentylammonium bromide, A change in the amount of latent heat of the hydrate or the heat storage agent containing this as a main component can be suppressed to be small.

  (B) Regarding the addition amount of tetraisopentylammonium bromide as a supercooling inhibitor, for example, the weight ratio (percentage) of tetraisopentylammonium bromide to the aqueous solution of tetra-n-butylammonium bromide is within a predetermined range. It is preferable to add so that it becomes. When the amount is less than the lower limit of the predetermined range, the amount of tetraisopentylammonium bromide hydrate is reduced, it becomes difficult to form a nucleus of tetra-n-butylammonium bromide hydrate, and the effect of preventing overcooling is insufficient. To do. On the other hand, if it exceeds the upper limit of the predetermined range, a hydrate produced from an aqueous solution containing tetra nbutylammonium bromide and tetraisopentylammonium bromide or a hydrate containing tetra nbutylammonium bromide, Hydrate containing tetraisopentylammonium bromide, and hence the heat storage amount of the heat storage agent mainly composed of the hydrate, is affected, and the amount of heat storage that can store heat in the temperature range of 3-15 ° C is significantly reduced. End up. Therefore, by making the addition of tetraisopentylammonium bromide in an appropriate amount (or in an appropriate amount range), it is possible to reduce the adverse effect on the thermal properties of the main component of the heat storage agent as much as possible by adding an anti-cooling agent, while supercooling. The effect of prevention can be made more reliable or effective.

  (C) Regarding the addition amount of the alkali metal phosphate as the supercooling inhibitor, the weight ratio (percentage) of the alkali metal phosphate to the aqueous solution of tetra-n-butylammonium bromide is within a predetermined range. It is preferable to add. When the amount is less than the lower limit of the predetermined range, the amount of alkali metal phosphate is reduced, and it becomes difficult to form nuclei of tetra n-butylammonium bromide hydrate, and the effect of preventing supercooling is insufficient. On the other hand, when the upper limit of the predetermined range is exceeded, a hydrate produced from an aqueous solution containing tetra nbutylammonium bromide or a hydrate containing tetra nbutylammonium bromide, The amount of heat stored in the heat storage agent as the main component is affected, and the amount of stored heat that can be stored in the temperature range of 3 to 15 ° C. is significantly reduced. Therefore, by making the addition of the alkali metal phosphate an appropriate amount (or in an appropriate range), it is possible to prevent the overcooling while reducing the adverse effect on the thermal properties of the main component of the heat storage agent by adding the supercooling inhibitor as much as possible. The effect of can be made more reliable or effective.

  A typical example of an alkali metal phosphate is disodium hydrogen phosphate. Disodium hydrogen phosphate can be used in any form, such as an anhydride or 12 hydrate.

  (D) It is effective to use a cellulose derivative as a substance that can effectively suppress sedimentation of alkali metal phosphate. Regarding the amount of addition, it is preferable to add the cellulose derivative so that the weight ratio (percentage) of the tetra-n-butylammonium bromide to the aqueous solution is not less than a predetermined weight ratio. If it is less than the predetermined weight ratio, the effect of suppressing the precipitation of the alkali metal phosphate is insufficient. On the other hand, if the weight ratio of the cellulose derivative to the aqueous solution of tetra-n-butylammonium bromide is increased unnecessarily, the weight ratio of tetra-n-butylammonium bromide becomes relatively low, resulting in a problem that the amount of stored heat is reduced.

2. Next, the addition of tetraisopentylammonium bromide as a supercooling inhibitor and alkali metal phosphate and the effect thereof will be described more specifically, and the results of examining the appropriate range of the addition rate will be described. Further, the addition of a cellulose derivative as a component for preventing the precipitation of alkali metal phosphate and the effect thereof will be described more specifically, and the results of examining the appropriate range of the addition rate will be described. A description will be given using disodium hydrogen phosphate (Na ₂ HPO ₄ ) as a typical example of an alkali metal phosphate and sodium carboxymethyl cellulose (CMCNa) as a typical example of a cellulose derivative.

<Measurement and evaluation method>
(A) Test raw material aqueous solution Tetraisopentylammonium bromide (TiPAB) was added to an aqueous solution of tetra-n-butylammonium bromide adjusted to several concentrations ranging from 15% by weight to 40.5% by weight (concentration giving a harmonic melting point). ), Disodium hydrogen phosphate (Na ₂ HPO ₄ ) and sodium carboxymethyl cellulose (CMCNa) are prepared and evaluated.

Weight ratio of tetraisopentylammonium bromide to tetranbutylammonium bromide aqueous solution (hereinafter referred to as tetraisopentylammonium bromide addition rate or TiPAB addition rate), weight of disodium hydrogen phosphate relative to tetranbutylammonium bromide aqueous solution The ratio (hereinafter referred to as disodium hydrogen phosphate addition rate or Na ₂ HPO ₄ addition rate) and the weight ratio of sodium carboxymethyl cellulose to the tetra-n-butylammonium bromide aqueous solution (hereinafter referred to as sodium carboxymethyl cellulose addition rate or CMCNa addition rate) In addition, an aqueous solution (raw aqueous solution) for preparing a hydrate is prepared by adding in addition (the hydrate produced by cooling this aqueous solution is dispersed or suspended in the aqueous solution by itself or That the slurry as a heat storage agent (particularly a latent heat storage agent) or those that can be used as the main component).

  About each test raw material aqueous solution prepared as described above, the following supercooling preventive properties, the heat storage amount of hydrates produced by cooling the raw material aqueous solution, the presence or absence of precipitation of disodium hydrogen phosphate in the raw material aqueous solution Measurement and evaluation of Through this measurement and evaluation, tetra-n-butylammonium bromide aqueous solution that is highly effective in preventing overcooling, has a small decrease in the amount of stored heat in the temperature range of 3 to 15 ° C., and can prevent precipitation of disodium hydrogen phosphate. The preferable composition of the heat storage agent containing the main component is clarified. That is, preferable ranges of tetraisopentylammonium bromide addition rate, disodium hydrogenphosphate addition rate, and sodium carboxymethylcellulose addition rate are determined.

(B) Evaluation method of supercooling prevention property 5 ml of the test raw material aqueous solution prepared according to the above procedure was charged in a glass test tube, immersed in a thermostat controlled at 3 ° C., cooled at 3 ° C. for 30 minutes, and hydrated. It was investigated whether or not a product crystal was formed. If a hydrate crystal is formed, it is evaluated that an effect of preventing overcooling or preventing overcooling is observed at 3 ° C. Furthermore, the test tube loaded with the raw material aqueous solution is alternately immersed in a thermostat controlled at 3 ° C. and a thermostat controlled at 20 ° C., and cooled to 3 ° C. to form a hydrate, Decrease in supercooling prevention performance when it is recognized that there is no deterioration in supercooling prevention performance after repeating the operations of hydrate formation or coagulation and melting to melt the hydrate produced by heating 1000 times. It is evaluated that it has no durability or supercooling prevention effect. The same evaluation is performed when the cooling temperature is 1 ° C.

  In Table 1, Table 2, Table 9 and Table 10 described later, there is an effect of preventing overcooling or an ability to prevent overcooling for the evaluation of overcooling prevention, and no decrease is observed after 1000 times of solidification and melting. Is marked with ◯ when supercooling is not released and hydrate crystals are not formed, i.e., when there is no supercooling effect or supercooling prevention property, or when a decrease is observed. did.

(C) Measurement / evaluation method of heat storage amount The heat storage amount of the hydrate produced | generated by cooling the raw material aqueous solution prepared by said point is measured by the heat insulation type continuous method. The heat storage amount here refers to the difference in enthalpy measured between 3 ° C. and 15 ° C. after holding the sample at 3 ° C. for 30 minutes and then heating to 15 ° C. with a heat input of 1.0 W. It is the sum of the thermal energy corresponding to the latent heat in the temperature range of ° C, the sensible heat of the raw material aqueous solution, and the sensible heat of the hydrate, and is expressed as the amount of heat per volume kJ / L.

  Regarding the evaluation of the heat storage amount, compared with the heat storage amount 148 kJ / L in the temperature range of 3 to 15 ° C. of normal pentadecane (NPD) used as the latent heat storage agent, if it is 148 kJ / L or more, it is sufficient as the latent heat storage agent It evaluated that it had heat storage amount, and in below-mentioned Tables 3-8, 11-16, (circle) was described and x was described if it was less than 148 kJ / L.

(D) Evaluation method of sedimentation of disodium hydrogen phosphate The test raw material aqueous solution prepared by the above procedure is allowed to stand, and the occurrence of sedimentation of disodium hydrogen phosphate crystals is observed. In Tables 17 to 19, which will be described later, when precipitation of disodium hydrogen phosphate was not observed, ◯ was marked, and when precipitation of disodium hydrogen phosphate was recognized, x was marked.

<Results of measurement and evaluation>
(1) Preferred range of addition rate of tetraisopentylammonium bromide (1-1) Lower limit of preferred range of addition rate of tetraisopentylammonium bromide Tetraisopentylammonium bromide to tetra-n-butylammonium bromide (TBAB) aqueous solution ( The lower limit of the preferred weight ratio range of TiPAB) was examined by evaluating the anti-cooling property of aqueous solutions having a weight concentration of tetra-n-butylammonium bromide of 15% by weight, 30% by weight and 40.5% by weight.

(1-1-1) Cooling temperature 3 ° C
A raw material aqueous solution was prepared by adding tetraisopentylammonium bromide in several addition ratios to 15%, 30% and 40.5% by weight aqueous solutions of tetra-n-butylammonium bromide. More specifically, the weight ratio of tetraisopentylammonium bromide to the tetra-n-butylammonium bromide aqueous solution (TiPAB addition rate) is 0.05%, 0.1%, 0.15%, and disodium hydrogen phosphate. A raw material aqueous solution having an addition rate of 0.05% and a sodium carboxylmethylcellulose addition rate of 0.1% is prepared, and overcooling prevention properties when the cooling temperature is 3 ° C. for each raw material aqueous solution thus prepared. Was evaluated. The results are shown in Table 1 below.

  From Table 1 above, it can be seen that when the TiPAB addition rate is less than 0.1%, there is no effect of preventing overcooling at a cooling temperature of 3 ° C. That is, when tetraisopentylammonium bromide is added to an aqueous solution of 15% to 40.5% by weight of tetra-n-butylammonium bromide, if the addition rate of TiPAB is in the range of 0.1% or more, the cooling temperature 3 At ℃, there is no deterioration of the supercooling prevention property or durability of the supercooling prevention effect.

  In order to maintain the COP of the refrigerator of the air conditioner at a high level and realize energy saving, the latent heat storage agent for air conditioning should be capable of storing heat at a temperature higher than 0 ° C, more preferably at 3 ° C or higher. Required. Therefore, in order to realize that the latent heat storage agent produced from the aqueous solution of tetra-n-butylammonium bromide has no deterioration of the supercooling prevention property or has the durability of the supercooling prevention effect at the cooling temperature of 3 ° C. In addition, when tetraisopentylammonium bromide is added to an aqueous solution of tetra-n-butylammonium bromide, the lower limit of the TiPAB addition rate is 0.1%.

(1-1-2) Cooling temperature 1 ° C
When the cooling temperature is 3 ° C., the lower limit of the TiPAB addition rate is 0.1%, but the lower limit of the TiPAB addition rate was also evaluated when the cooling temperature was 1 ° C. A raw material aqueous solution was prepared by adding tetraisopentylammonium bromide in several addition ratios to 15%, 30% and 40.5% by weight aqueous solutions of tetra-n-butylammonium bromide. More specifically, the weight ratio of tetraisopentylammonium bromide to the tetra-n-butylammonium bromide aqueous solution (TiPAB addition ratio) is 0.02%, 0.05%, 0.1%, and disodium hydrogen phosphate. A raw material aqueous solution with an addition rate of 0.05% and a sodium carboxylmethylcellulose addition rate of 0.1% is prepared, and overcooling prevention properties when the cooling temperature is 1 ° C. for each raw material aqueous solution thus prepared. Was evaluated. The results are shown in Table 2 below.

  From Table 2 above, it can be seen that when the TiPAB addition rate is less than 0.05%, there is no effect of preventing overcooling at a cooling temperature of 1 ° C. That is, when tetraisopentylammonium bromide is added to an aqueous solution of 15% to 40.5% by weight of tetra-n-butylammonium bromide, if the addition rate of TiPAB is in the range of 0.05% or more, the cooling temperature is 1 At ℃, there is no deterioration of the supercooling prevention property or durability of the supercooling prevention effect.

(1-2) Upper limit of preferred range of tetraisopentylammonium bromide addition rate Upper limit of preferred weight ratio range of tetraisopentylammonium bromide (TiPAB) to tetra-n-butylammonium bromide (TBAB) aqueous solution The amount of heat storage was measured and evaluated for several concentrations of an aqueous solution having a concentration of tetra-n-butylammonium from 15% by weight to 40.5% by weight (concentration giving a harmonic melting point).

  Several addition rates of tetraisopentylammonium bromide in aqueous solutions of 15%, 20%, 25%, 30%, 35% and 40.5% by weight of tetra-n-butylammonium bromide (TBAB) Was added to prepare a raw material aqueous solution. More specifically, as shown in Tables 2-7, for each weight percent aqueous solution of tetra nbutylammonium bromide (TBAB), the weight ratio of tetraisopentylammonium bromide to tetra nbutylammonium bromide aqueous solution. (TiPAB addition rate) was added in several types, a raw material aqueous solution with 0.1% disodium hydrogenphosphate addition rate and 0.1% sodium carboxylmethylcellulose addition rate, and several TiPAB addition rates were added. A raw material aqueous solution having a disodium oxyhydrogen addition rate of 0.5% and a sodium carboxylmethylcellulose addition rate of 0.5% was prepared, and each raw material aqueous solution thus prepared was in a temperature range of 3 to 15 ° C. The amount of heat stored is measured and compared with the amount of stored heat of normal pentadecane (NPD) 148 kJ / L. The heat storage amount was evaluated.

The results are shown in Tables 3 to 8 below.

  From the above Tables 3 to 8, the following can be understood.

  -In a 15 wt% aqueous solution of tetra-n-butylammonium bromide, when the TiPAB addition rate exceeds 3.0%, the heat storage amount in the temperature range of 3 to 15 ° C is lower than the heat storage amount of normal pentadecane 148 kJ / L. Therefore, the TiPAB addition rate is preferably 3.0% or less.

  In a 20% by weight aqueous solution of tetra-n-butylammonium bromide, when the TiPAB addition rate exceeds 7.0%, the heat storage amount in the temperature range of 3 to 15 ° C. is lower than the heat storage amount of normal pentadecane 148 kJ / L. Therefore, the TiPAB addition rate is preferably 7.0% or less.

  In a 25 wt% aqueous solution of tetra n-butylammonium bromide, when the TiPAB addition rate exceeds 14.0%, the heat storage amount in the temperature range of 3 to 15 ° C is lower than the heat storage amount of normal pentadecane of 148 kJ / L. Therefore, the TiPAB addition rate is preferably 14.0% or less.

  In a 30 wt% aqueous solution of tetra n-butylammonium bromide, when the TiPAB addition rate exceeds 12.0%, the heat storage amount in the temperature range of 3 to 15 ° C is lower than the heat storage amount 148 kJ / L of normal pentadecane. Therefore, the TiPAB addition rate is preferably 12.0% or less.

  -In a 35 wt% aqueous solution of tetra n-butylammonium bromide, when the TiPAB addition rate exceeds 9.0%, the heat storage amount in the temperature range of 3 to 15 ° C is lower than the heat storage amount of normal pentadecane 148 kJ / L. Therefore, the TiPAB addition rate is preferably 9.0% or less.

  In a 40.5 wt% aqueous solution of tetra n-butylammonium bromide, when the TiPAB addition rate exceeds 8.0%, the heat storage amount in the temperature range of 3 to 15 ° C. is lower than the heat storage amount of normal pentadecane 148 kJ / L. Therefore, the TiPAB addition rate is preferably 8.0% or less.

  From the results shown in Table 1 and the results shown in Tables 3 to 8, the following can be understood.

  When adding tetraisopentylammonium bromide to an aqueous solution of tetra-n-butylammonium bromide to obtain a raw material aqueous solution for a heat storage agent, the supercooling prevention property is excellent and the heat storage amount in the temperature range of 3 to 15 ° C is sufficient. In order to obtain a large heat storage agent, the following TiPAB addition ratio is preferable.

  Corresponding to the TBAB concentration, which is the weight concentration of tetra-n-butylammonium bromide in an aqueous solution containing tetra-n-butylammonium bromide as a solute, the preferred range of TiPAB addition rate is as follows.

When the TBAB concentration is 15% by weight or more and less than 20% by weight, the TiPAB addition rate is 0.1% or more and 3.0% or less,
When the TBAB concentration is 20% by weight or more and less than 25% by weight, the TiPAB addition rate is 0.1% or more and 7.0% or less,
When the TBAB concentration is 25% by weight or more and less than 30% by weight, the TiPAB addition rate is 0.1% or more and 12.0% or less,
When the TBAB concentration is 30% by weight or more and less than 35% by weight, the TiPAB addition rate is 0.1% or more and 9.0% or less,
When the TBAB concentration is 35% by weight or more and 40.5% by weight or less, the TiPAB addition rate is preferably in the range of 0.1% or more and 8.0% or less.

  Further, when the TBAB concentration is 20% by weight or more and less than 40.5% by weight, the TiPAB addition rate is preferably in the range of 0.1% or more and 7.0% or less.

  In addition, in the evaluation of the heat storage amount shown in Tables 3 to 8, several types of TiPAB addition rates were used, the disodium hydrogen phosphate addition rate was 0.1% or 0.5%, and the sodium carboxylmethylcellulose addition rate was 0.00. The raw material aqueous solution set to 1% or 0.5% was evaluated, and the preferable range of the TiPAB addition rate was determined. However, a preferable range of the TiPAB addition rate such that the heat storage amount in the temperature range of 3 to 15 ° C. exceeds the thermal storage amount 148 kJ / L of normal pentadecane, the disodium hydrogen phosphate addition rate, and the sodium carboxylmethylcellulose addition rate, Needless to say, it may be determined.

(2) Preferred range of addition rate of disodium hydrogen phosphate (2-1) Lower limit of preferred range of addition rate of disodium hydrogen phosphate Disodium hydrogen phosphate (Na ₂ HPO) to tetra-n-butylammonium bromide (TBAB) aqueous solution ₄ ) The lower limit of the preferred range of the weight ratio was examined by evaluating the anti-cooling property of aqueous solutions having a weight concentration of tetra-n-butylammonium bromide of 15% by weight, 30% by weight and 40.5% by weight.

(2-1-1) Cooling temperature 3 ° C
A raw material aqueous solution was prepared by adding disodium hydrogen phosphate to 15%, 30% and 40.5% by weight aqueous solutions of tetra-n-butylammonium bromide at several addition rates. More specifically, the weight ratio of disodium hydrogen phosphate to the aqueous solution of tetra-n-butylammonium bromide (Na ₂ HPO ₄ addition ratio) was set to 0.05%, 0.1%, 0.15%, and tetrabromide bromide. Prepare a raw material aqueous solution with an isopentylammonium addition rate of 0.05% and a sodium carboxymethylcellulose addition rate of 0.1%. The anti-cooling property was evaluated. The results are shown in Table 9 below.

From Table 9 above, it can be seen that when the Na ₂ HPO ₄ addition ratio is less than 0.1%, there is no effect of preventing overcooling at a cooling temperature of 3 ° C. That is, when disodium hydrogenphosphate is added to an aqueous solution of 15% to 40.5% by weight of tetra-n-butylammonium bromide, if the Na ₂ HPO ₄ addition ratio is in the range of 0.1% or more, cooling is performed. At a temperature of 3 ° C., there is no deterioration of the supercooling prevention property or durability of the supercooling prevention effect.

In order to realize that the latent heat storage agent produced from the aqueous solution of tetra-n-butylammonium bromide has no deterioration in the supercooling prevention property or has the durability of the supercooling prevention effect at a cooling temperature of 3 ° C. When disodium hydrogen phosphate is added to an aqueous solution of tetra-n-butylammonium, the lower limit of the Na ₂ HPO ₄ addition rate is 0.1%.

(2-1-2) Cooling temperature 1 ° C
When the cooling temperature is 3 ° C., the lower limit of the Na ₂ HPO ₄ addition rate is 0.1%, but the lower limit of the Na ₂ HPO ₄ B addition rate was also evaluated when the cooling temperature was 1 ° C. A raw material aqueous solution was prepared by adding disodium hydrogen phosphate to 15%, 30% and 40.5% by weight aqueous solutions of tetra-n-butylammonium bromide at several addition rates. More specifically, the weight ratio of disodium hydrogen phosphate to the aqueous solution of tetra n-butylammonium bromide (Na ₂ HPO ₄ addition ratio) is 0.02%, 0.05%, 0.1%, A raw material aqueous solution having an addition rate of isopentylammonium of 0.05% and a sodium carboxylmethylcellulose addition rate of 0.1% was prepared, and for each of the raw material aqueous solutions thus prepared, the cooling temperature was 1 ° C. The anti-cooling property was evaluated. The results are shown in Table 10 below.

From Table 10 above, it can be seen that when the Na ₂ HPO ₄ addition ratio is less than 0.05%, there is no effect of preventing overcooling at a cooling temperature of 1 ° C. That is, when adding disodium hydrogen phosphate to an aqueous solution of 15% to 40.5% by weight of tetra-n-butylammonium bromide, if the Na ₂ HPO ₄ addition ratio is in the range of 0.05% or more, cooling is performed. At a temperature of 1 ° C., there is no deterioration of the supercooling prevention property or there is durability of the supercooling prevention effect.

(2-2) Upper limit of preferred range of disodium hydrogen phosphate addition rate The upper limit of the preferred weight ratio range of disodium hydrogen phosphate (Na ₂ HPO ₄ ) to tetra-n-butylammonium bromide (TBAB) aqueous solution is The amount of heat storage was measured and evaluated for several concentrations of aqueous solutions of tetra-n-butylammonium bromide having a concentration of 15 to 40.5% by weight (concentration giving a harmonic melting point).

Disodium hydrogen phosphate was added to several 15%, 20%, 25%, 30%, 35% and 40.5% by weight aqueous solutions of tetra-n-butylammonium bromide (TBAB) at several addition rates. The raw material aqueous solution was prepared by adding. More specifically, as shown in Tables 9 to 14, for each weight% aqueous solution of tetra n-butylammonium bromide (TBAB), the weight ratio of disodium hydrogen phosphate to the aqueous solution of tetra-n-butylammonium bromide ( Na ₂ HPO ₄ addition rate) was added as several types, the raw material aqueous solution with 0.1% tetraisopentylammonium bromide addition rate and 0.1% sodium carboxymethyl cellulose addition rate, and Na ₂ HPO ₄ addition rate A raw material aqueous solution prepared by adding several kinds of tetraisopentylammonium bromide addition rate and 0.5% sodium carboxylmethylcellulose sodium addition rate was prepared. Measure the amount of heat storage in the temperature range of -15 ℃, normal pentadecane (NPD) Compared to the amount of stored heat 148kJ / L, they were evaluated for heat storage amount.

The results are shown in Tables 11 to 16 below.

  From the above Tables 11 to 16, the following can be understood.

In a 15% by weight aqueous solution of tetra n-butylammonium bromide, when the Na ₂ HPO ₄ addition rate exceeds 8.0%, the heat storage amount in the temperature range of 3 to 15 ° C. is lower than the heat storage amount of normal pentadecane 148 kJ / L . Therefore, the Na ₂ HPO ₄ addition rate is preferably 8.0% or less.

In a 20% by weight aqueous solution of tetra n-butylammonium bromide, when the Na ₂ HPO ₄ addition rate exceeds 10.0%, the heat storage amount in the temperature range of 3 to 15 ° C. is lower than the heat storage amount of normal pentadecane 148 kJ / L . Therefore, the Na ₂ HPO ₄ addition rate is preferably 10.0% or less.

In a 25 wt% aqueous solution of tetra n-butylammonium bromide, when the Na ₂ HPO ₄ addition rate exceeds 13.0%, the heat storage amount in the temperature range of 3 to 15 ° C. is lower than the heat storage amount of normal pentadecane 148 kJ / L . Accordingly, the Na ₂ HPO ₄ addition rate is preferably 13.0% or less.

In a 30 wt% aqueous solution of tetra n-butylammonium bromide, when the Na ₂ HPO ₄ addition rate exceeds 11.0%, the heat storage amount in the temperature range of 3 to 15 ° C. is lower than the heat storage amount of normal pentadecane 148 kJ / L . Therefore, the Na ₂ HPO ₄ addition rate is preferably 11.0% or less.

In a 35 wt% aqueous solution of tetra n-butylammonium bromide, when the Na ₂ HPO ₄ addition rate exceeds 9.0%, the heat storage amount in the temperature range of 3 to 15 ° C is lower than the heat storage amount of normal pentadecane 148 kJ / L . Therefore, the Na ₂ HPO ₄ addition rate is preferably 9.0% or less.

In a 40.5 wt% aqueous solution of tetra n-butylammonium bromide, when the Na ₂ HPO ₄ addition rate exceeds 7.0%, the heat storage amount in the temperature range of 3 to 15 ° C. is the heat storage amount of normal pentadecane 148 kJ / L Below. Therefore, the Na ₂ HPO ₄ addition rate is preferably 7.0% or less.

  From the results shown in Table 9 and the results shown in Tables 11 to 16, the following can be understood.

When disodium hydrogen phosphate is added to an aqueous solution of tetra-n-butylammonium bromide to obtain a raw material aqueous solution of a heat storage agent, the supercooling prevention property is excellent and the heat storage amount in a temperature range of 3 to 15 ° C. is sufficiently large. to obtain a heat storage agent, it is preferable that the scope of the following _Na 2 HPO ₄ addition rate.

Corresponding to the TBAB concentration, which is the weight concentration of tetra nbutylammonium bromide in an aqueous solution containing tetra nbutylammonium bromide as a solute, the preferred range of the Na ₂ HPO ₄ addition rate is as follows.

When the TBAB concentration is 15% by weight or more and less than 20% by weight, the Na ₂ HPO ₄ addition rate is 0.1% or more and 8.0% or less,
When the TBAB concentration is 20% by weight or more and less than 25% by weight, the Na ₂ HPO ₄ addition rate is 0.1% or more and 10.0% or less,
When the TBAB concentration is 25% by weight or more and less than 30% by weight, the Na ₂ HPO ₄ addition rate is 0.1% or more and 11.0% or less,
When the TBAB concentration is 30% by weight or more and less than 35% by weight, the Na ₂ HPO ₄ addition rate is 0.1% or more and 9.0% or less,
When the TBAB concentration is 35% by weight or more and 40.5% by weight or less, the Na ₂ HPO ₄ addition rate is preferably in the range of 0.1% or more and 7.0% or less.

In addition, when the TBAB concentration is 15% by weight or more and less than 40.5% by weight, the Na ₂ HPO ₄ addition rate is preferably in the range of 0.1% or more and 7.0% or less.

In addition, in the evaluation of the heat storage amount shown in Tables 11 to 16, the Na ₂ HPO ₄ addition rate was several, the tetraisopentylammonium bromide addition rate was 0.1% or 0.5%, and sodium carboxymethyl cellulose was added. The raw material aqueous solution with a rate of 0.1% or 0.5% was evaluated to obtain a preferable range of the TiPAB addition rate. However, the preferable range of the Na ₂ HPO ₄ addition rate, the tetraisopentylammonium bromide addition rate, and the sodium carboxymethyl cellulose addition such that the heat storage amount in the temperature range of 3 to 15 ° C. exceeds the thermal storage amount of normal pentadecane 148 kJ / L. It goes without saying that the rate may be determined.

(3) Preferred range of sodium carboxymethyl cellulose addition rate (3-1) Lower limit of preferred range of sodium carboxymethyl cellulose addition rate Preferred range of weight ratio of sodium carboxymethyl cellulose (CMCNa) to tetra-n-butylammonium bromide (TBAB) aqueous solution The lower limit was evaluated by evaluating the anti-settling property of disodium hydrogen phosphate for aqueous solutions containing 15%, 30% and 40.5% by weight of tetra-n-butylammonium bromide.

  Three kinds of sodium carboxymethylcellulose having an average molecular weight of about 10,000, about 200,000 and about 700,000 are added to 15%, 30% and 40.5% by weight aqueous solutions of tetra-n-butylammonium bromide at several addition rates, respectively. By doing this, a raw material aqueous solution was prepared. Sodium carboxymethylcellulose having an average molecular weight of about 10,000, about 200,000 and about 700,000 corresponds to an average degree of polymerization of 40 to 50, 800 to 1000, 3000 to 3200. More specifically, the weight ratio (CMCNa addition rate) of sodium carboxymethyl cellulose to tetra-n-butylammonium bromide aqueous solution is several kinds in the range of 0.03% to 0.2%, and 15 wt. % Aqueous solution of a raw material having a tetraisopentylammonium bromide addition rate of 0.5% and a disodium hydrogen phosphate addition rate of 0.5%, a tetraisobutylammonium bromide solution of 30% by weight of tetraisobromide bromide. The raw material aqueous solution with 4% pentylammonium addition rate and 4% disodium hydrogenphosphate addition rate and 30.5% tetraisopentylammonium bromide addition rate with 40.5% by weight aqueous solution of tetra-n-butylammonium bromide, phosphorus A raw material aqueous solution with a disodium oxyhydrogen addition rate of 3% was prepared and thus prepared. The anti-settling property of disodium hydrogen phosphate was evaluated for each raw material aqueous solution.

The results are shown in Tables 17-19 below.

  From Tables 17 to 19, it can be seen that when the CMCNa addition rate is less than 0.1%, there is no effect of preventing precipitation of disodium hydrogenphosphate. That is, when sodium carboxymethylcellulose is added to an aqueous solution of 15% to 40.5% by weight of tetra-n-butylammonium bromide, if the CMCNa addition rate is in the range of 0.1% or more, disodium hydrogen phosphate Has settling prevention properties.

(3-2) Upper limit of preferable range of sodium carboxylmethylcellulose addition ratio When the weight ratio of sodium carboxylmethylcellulose to the aqueous solution of tetranbutylammonium bromide is increased unnecessarily, the weight ratio of tetranbutylammonium bromide in the aqueous raw material solution is increased. Since it becomes relatively low and the heat storage amount decreases, it is preferable that the sodium carboxymethyl cellulose addition rate is 10% or less.

  Sodium carboxymethyl cellulose has various degrees of etherification or substitution. From the viewpoint of the stability of the raw material aqueous solution to which sodium carboxymethyl cellulose is added, those having a degree of etherification or substitution of 0.7 or more are preferable. .8 or more is more preferable. The reason is as follows.

  Sodium carboxymethylcellulose is unstable to strong basicity. That is, since sodium carboxymethylcellulose is anionic, depolymerization proceeds with oxygen in the presence of a cation, and as a result, the viscosity of an aqueous solution containing sodium carboxymethylcellulose may decrease. On the other hand, sodium salt of carboxymethylcellulose may be substituted in the presence of an acid to lower the solubility. The higher the degree of etherification, the more sodium carboxymethylcellulose is chemically stable and the higher the resistance to such bases and acids. The pH of the raw material aqueous solution of the heat storage agent of the present invention is almost in the neutral range, but considering the long-term stability, the degree of etherification of sodium carboxymethylcellulose, or the degree of substitution almost equivalent to the degree of etherification is 0.7 or more. The thing of 0.8 is more preferable.

  The heat storage agent of the present invention is constituted by adding tetraisopentylammonium bromide, alkali metal phosphate, and cellulose derivative to an aqueous solution of tetra-n-butylammonium bromide. Additives may be added. For example, the following corrosion inhibitors may be added in order to suppress corrosion of the metal material of a container for storing a heat storage agent or piping equipment to be transported. Moreover, you may make it exhibit a gel form by adding the thickening / gelling agent shown below.

<Corrosion inhibitor>
At least one of the substances shown in groups 1 to 4 is added.

Group 1: Alkali metal hydroxides Group 2: Anhydrous salts or hydrates of the following substances, whose cations are sodium, potassium, lithium, calcium, magnesium, strontium Nitrite, nitrate, tungstate, molybdic acid Salt, chromate, oleate, polyphosphate, metasilicate, thiosulfate, sulfite, borate Group 3: hydrazine, acrylic polymer, calcium chloride, calcium bromide, calcium iodide Group 4: Phosphonic acid, phosphinopolycarboxylic acid, phosphonocarboxylic acid, maleic acid polymer, acrylic acid polymer, thiourea derivatives such as diethylurea and dibutylthiourea, azole compounds Corrosion inhibitors in tetranbutylammonium bromide aqueous solution The concentration range of corrosion inhibitors when adding Is then, preferably in a range of 0.001 wt% to 5 wt%. If it is less than 0.001% by weight, a sufficient corrosion inhibiting effect cannot be obtained, and if it is added in a larger amount than 5% by weight, the freezing point of the aqueous raw material solution changes, so that sufficient heat storage performance cannot be obtained.

<Thickening / gelling agent>
As the thickening / gelling agent, the following substances may be used, or they may be used in combination.

・ Polysaccharide tragacanth gum, pectin, guar gum, locust bean gum, spino gum, galactomannan, tamarind seed polysaccharide, carrageenan, farselarene, xanthan gum, pullulan, gellan gum, gum arabic, tara gum Potato starch, wheat starch, rice starch, tapioca starch) -surfactant β-naphthalene sulfonate condensate, creosote oil sodium sulfonate condensate melamine resin sodium sulfonate, lignin sulfonate, Nonylphenol polyoxyethylene ether, sodium gluconate, sulfonates (alkylbenzene sulfonate), sulfate esters, phosphate esters, polyoxyethylene compounds (polyoxyethylene) Ethylene stearyl ether)
・ Calcium salt calcium formate, calcium acetate, calcium chloride, calcium tartrate, calcium lactate ・ Polymer sodium polyacrylate, polyacrylamide, polyglycerin, polyvinyl alcohol, gelatin, agar-fatty acid (linear fatty acid, side chain fatty acid)
Palmitic acid, stearic acid, hydroxystearic acid, behenic acid, montanic acid, lauric acid, ricinoleic acid, octylic acid / fatty acid metal salt Lithium salt, sodium salt, potassium salt, calcium salt, aluminum salt, barium salt, magnesium of the above fatty acids Salt, zinc salt.

Lithium stearate, sodium stearate, potassium stearate, magnesium stearate, calcium stearate, barium stearate, zinc stearate, calcium laurate, barium laurate, zinc laurate, calcium ricinoleate, barium ricinoleate, zinc ricinoleate, Zinc octylate When adding a thickening / gelling agent to an aqueous solution of tetra-n-butylammonium bromide, the concentration range of the thickening / gelling agent is preferably 0.01% to 5% by weight. . If it is less than 0.01% by weight, a sufficient gelled state is not exhibited. On the other hand, even if added in a larger amount than 5% by weight, the gelation effect is not improved, and the freezing point of the aqueous raw material solution changes, so that sufficient heat storage performance cannot be obtained.

  There is no restriction | limiting in particular about the manufacturing method of the thermal storage agent of this invention. For example, after adding a predetermined amount of sodium carboxymethylcellulose to water and mixing thoroughly, mix a predetermined amount of tetra nbutylammonium bromide, then add a predetermined amount of tetraisopentylammonium bromide and mix thoroughly Finally, there is a method for producing a heat storage agent by adding a predetermined amount of disodium hydrogen phosphate. You may add a corrosion inhibitor and a gelatinizer as needed.

  There are no particular restrictions on the order of blending the constituent materials of these heat storage agents, but sodium carboxymethylcellulose is relatively flocculated and may take time to dissolve, so it is desirable to blend it at an early stage when the solute concentration of the raw material aqueous solution is low. . Further, stirring and mixing in a heated state is desirable in order to promote dissolution and mixing of these constituent substances. However, at a temperature of 100 ° C. or less, preferably at a temperature of 80 ° C. or less at which the irreversible change in the viscosity of sodium carboxymethylcellulose hardly occurs so that thermal decomposition of tetra-n-butylammonium bromide or tetraisopentylammonium bromide does not occur. It is preferable to mix and mix.

  The technical scope of the present invention is not limited by the above embodiments, and can be implemented in various forms without changing the gist of the invention. Further, the technical scope of the present invention extends to an equivalent range. The meaning or interpretation of each term in this specification does not preclude the technical scope of the present invention from reaching an equivalent range.

The present invention is based on each of the above findings. Among them, the heat storage agent according to the first embodiment of the present invention has an aqueous solution containing tetra-n-butylammonium bromide as a solute cooled to a hydrate formation temperature or lower. A heat storage agent containing clathrate hydrate formed by adding tetraisopentylammonium bromide, alkali metal phosphate and cellulose derivative to the aqueous solution, wherein the cellulose derivative is carboxylated at least one of cellulose derivatives, or a carboxyl group and carboxymethyl group having at least one of the groups and carboxymethyl groups, and is characterized in that a cellulose derivative having an alkali metal.

Heat storage agent according to a seventh embodiment of the present invention includes a heat storage agent according to any one of the embodiments of the first to sixth, at least one of the carboxyl group and carboxymethyl group, and the alkali metal The cellulose derivative is sodium carboxymethylcellulose.

The heat storage agent according to the eighth embodiment of the present invention is the heat storage agent according to the seventh embodiment, wherein the weight ratio of sodium carboxymethylcellulose to the aqueous solution containing tetra-n-butylammonium bromide as a solute is 0.1% or more. It is characterized by being 10.0% or less.
The heat storage agent according to the ninth aspect of the present invention is the heat storage agent according to any one of the first to eighth aspects, and is characterized in that a corrosion inhibitor is added.

Several addition rates of tetraisopentylammonium bromide in aqueous solutions of 15%, 20%, 25%, 30%, 35% and 40.5% by weight of tetra-n-butylammonium bromide (TBAB) Was added to prepare a raw material aqueous solution. More specifically, as shown in Tables 3-8 , the weight ratio of tetraisopentylammonium bromide to tetra-n-butylammonium bromide aqueous solution for each weight% concentration aqueous solution of tetra-n-butylammonium bromide (TBAB). (TiPAB addition rate) was added in several types, a raw material aqueous solution with 0.1% disodium hydrogenphosphate addition rate and 0.1% sodium carboxylmethylcellulose addition rate, and several TiPAB addition rates were added. A raw material aqueous solution having a disodium oxyhydrogen addition rate of 0.5% and a sodium carboxylmethylcellulose addition rate of 0.5% was prepared, and each raw material aqueous solution thus prepared was in a temperature range of 3 to 15 ° C. The amount of heat stored is measured and compared with the amount of stored heat of normal pentadecane (NPD) 148 kJ / L. The heat storage amount was evaluated.

Disodium hydrogen phosphate was added to several 15%, 20%, 25%, 30%, 35% and 40.5% by weight aqueous solutions of tetra-n-butylammonium bromide (TBAB) at several addition rates. The raw material aqueous solution was prepared by adding. More specifically, as shown in Tables 11 to 16 , for each weight% aqueous solution of tetra n-butylammonium bromide (TBAB), the weight ratio of disodium hydrogen phosphate to the aqueous solution of tetra-n-butylammonium bromide ( Na ₂ HPO ₄ addition rate) was added as several types, the raw material aqueous solution with 0.1% tetraisopentylammonium bromide addition rate and 0.1% sodium carboxymethyl cellulose addition rate, and Na ₂ HPO ₄ addition rate A raw material aqueous solution prepared by adding several kinds of tetraisopentylammonium bromide addition rate and 0.5% sodium carboxylmethylcellulose sodium addition rate was prepared. Measure the amount of heat storage in the temperature range of ~ 15 ° C, and then use normal pentadecane (NPD Compared to the quantity of thermal storage 148kJ / L, they were evaluated for heat storage amount.

Claims (8)

A heat storage agent comprising an clathrate hydrate produced by cooling an aqueous solution containing tetra-n-butylammonium bromide as a solute,
Tetraisopentylammonium bromide, alkali metal phosphate and cellulose derivative are added to the aqueous solution,
The cellulose derivative is a cellulose derivative having at least one of a carboxyl group and a carboxymethyl group, or a cellulose derivative having at least one of a carboxyl group and a carboxymethyl group and an alkali metal. . The concentration of tetra-n-butylammonium bromide in the aqueous solution containing tetra-n-butylammonium bromide as a solute is 20% by weight or more and 40.5% by weight or less,
The heat storage agent according to claim 1, wherein the weight ratio of tetraisopentylammonium bromide to an aqueous solution containing tetra-n-butylammonium bromide as a solute is 0.1% or more and 7.0% or less. The weight ratio of tetraisopentylammonium bromide (TiPAB) to an aqueous solution containing tetra-n-butylammonium bromide (TBAB) as a solute is tetra-n-butylammonium bromide in an aqueous solution containing tetra-n-butylammonium bromide (TBAB) as a solute. Corresponding to the TBAB concentration, which is the weight concentration of (TBAB),
When the TBAB concentration is 15% by weight or more and less than 20% by weight, the weight ratio is 0.1% or more and 3.0% or less,
When the TBAB concentration is 20% by weight or more and less than 25% by weight, the weight ratio is 0.1% or more and 7.0% or less,
When the TBAB concentration is 25% by weight or more and less than 30% by weight, the weight ratio is 0.1% or more and 12.0% or less,
When the TBAB concentration is 30% by weight or more and less than 35% by weight, the weight ratio is 0.1% or more and 9.0% or less,
2. The heat storage agent according to claim 1, wherein when the TBAB concentration is 35% by weight or more and 40.5% by weight or less, the weight ratio of T is 0.1% or more and 8.0% or less.   The heat storage agent according to any one of claims 1 to 3, wherein the alkali metal phosphate is disodium hydrogen phosphate. The concentration of tetra-n-butylammonium bromide in the aqueous solution containing tetra-n-butylammonium bromide as a solute is 15% by weight or more and 40.5% by weight or less,
The heat storage agent according to claim 4, wherein a weight ratio of disodium hydrogen phosphate to an aqueous solution containing tetra-n-butylammonium bromide as a solute is 0.1% or more and 7.0% or less. The weight ratio of disodium hydrogen phosphate to an aqueous solution containing tetra-n-butylammonium bromide (TBAB) as a solute is that of tetra-n-butylammonium bromide (TBAB) in an aqueous solution containing tetra-n-butylammonium bromide as a solute (TBAB). Corresponding to TBAB concentration which is weight concentration,
When the TBAB concentration is 15% by weight or more and less than 20% by weight, the weight ratio is 0.1% or more and 8.0% or less,
When the TBAB concentration is 20% by weight or more and less than 25% by weight, the weight ratio is 0.1% or more and 10.0% or less,
When the TBAB concentration is 25% by weight or more and less than 30% by weight, the weight ratio is 0.1% or more and 11.0% or less,
When the TBAB concentration is 30% by weight or more and less than 35% by weight, the weight ratio is 0.1% or more and 9.0% or less,
The heat storage agent according to claim 4, wherein the weight ratio is 0.1% or more and 7.0% or less when the TBAB concentration is 35% by weight or more and 40.5% by weight or less.   The heat storage agent according to any one of claims 1 to 6, wherein the cellulose derivative having at least one of the carboxyl group and the carboxymethyl group and the alkali metal is sodium carboxymethyl cellulose.   The heat storage agent according to claim 7, wherein a weight ratio of sodium carboxymethylcellulose to an aqueous solution containing tetra-n-butylammonium bromide as a solute is 0.1% or more and 10.0% or less.